全文获取类型
收费全文 | 96781篇 |
免费 | 4514篇 |
国内免费 | 45篇 |
专业分类
林业 | 6680篇 |
农学 | 3705篇 |
基础科学 | 565篇 |
12394篇 | |
综合类 | 13868篇 |
农作物 | 4895篇 |
水产渔业 | 5658篇 |
畜牧兽医 | 44796篇 |
园艺 | 1944篇 |
植物保护 | 6835篇 |
出版年
2018年 | 3834篇 |
2017年 | 3887篇 |
2016年 | 2345篇 |
2015年 | 1106篇 |
2014年 | 1242篇 |
2013年 | 3366篇 |
2012年 | 3053篇 |
2011年 | 4833篇 |
2010年 | 3856篇 |
2009年 | 3010篇 |
2008年 | 3950篇 |
2007年 | 4117篇 |
2006年 | 2425篇 |
2005年 | 2268篇 |
2004年 | 2150篇 |
2003年 | 2286篇 |
2002年 | 2039篇 |
2001年 | 2482篇 |
2000年 | 2480篇 |
1999年 | 1993篇 |
1998年 | 851篇 |
1997年 | 850篇 |
1995年 | 867篇 |
1994年 | 792篇 |
1993年 | 782篇 |
1992年 | 1575篇 |
1991年 | 1813篇 |
1990年 | 1626篇 |
1989年 | 1610篇 |
1988年 | 1486篇 |
1987年 | 1473篇 |
1986年 | 1482篇 |
1985年 | 1500篇 |
1984年 | 1241篇 |
1983年 | 1133篇 |
1982年 | 784篇 |
1979年 | 1230篇 |
1978年 | 951篇 |
1977年 | 947篇 |
1976年 | 962篇 |
1975年 | 992篇 |
1974年 | 1141篇 |
1973年 | 1115篇 |
1972年 | 1060篇 |
1971年 | 945篇 |
1970年 | 960篇 |
1969年 | 978篇 |
1968年 | 891篇 |
1967年 | 940篇 |
1966年 | 814篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
992.
Sarah C. Roode Heather R. Shive Willemijn Hoorntje Jennifer Bernard Devorah M. Stowe Roy R. Pool Carol B. Grindem 《Veterinary clinical pathology / American Society for Veterinary Clinical Pathology》2018,47(3):484-488
A 20‐month‐old female spayed Staffordshire Terrier (22.3 kg) presented to the Orthopedic Surgery Service at North Carolina State University Veterinary Teaching Hospital for evaluation of a 6‐week history of toe‐touching to nonweight‐bearing lameness in the right hind limb. Radiographs of the right stifle revealed a multiloculated lytic lesion of the distal femur, with a large open lytic zone centrally, numerous osseous septations peripherally, and focal areas of cortical thinning and loss. An aspirate of the right distal femoral lesion yielded mildly cloudy serosanguineous fluid. Cytologic examination of the fluid revealed a pleomorphic population of discrete cells that exhibited marked anisocytosis and anisokaryosis and a variable nuclear‐to‐cytoplasmic (N:C) ratio, which were interpreted as probable neoplastic cells, with few macrophages, and evidence of hemorrhage. Given the clinical signs of pain, lesion size, and concern for malignant neoplasia, amputation of the right hind limb was performed. Histologically, the lesion had undulating walls 1‐3 mm thick with a continuous outer layer of dense fibrous tissue and an inner layer composed of reactive cancellous bone with no cortical compacta remaining. Remnants of thin fibrous or fibro‐osseous septa projected from the bony wall into the cyst lumen. The final histologic diagnosis was a benign multiloculated solitary (unicameral) bone cyst of the distal right femur. Based on the histopathologic findings, it was speculated that the cells identified on cytology were a mixture of developing osteoclasts, osteoblasts, endothelial, and stromal cells. This is the first report describing the cytologic examination of a solitary bone cyst in veterinary medicine. 相似文献
993.
Meta‐analysis of the energy and protein requirements of hair sheep raised in the tropical region of Brazil
下载免费PDF全文
![点击此处可从《Journal of animal physiology and animal nutrition》网站下载免费的PDF全文](/ch/ext_images/free.gif)
A. P. Oliveira E. S. Pereira S. Biffani A. N. Medeiros A. M. A. Silva R. L. Oliveira M. I. Marcondes 《Journal of animal physiology and animal nutrition》2018,102(1):e52-e60
The objective of this study was to estimate, through mathematical models, energy and protein requirements for maintenance and gain of hair sheep raised in the tropical region of Brazil. To determine the equation parameters, a meta‐analysis of seven independent experiments of nutrient requirements was performed, comprising a total of 243 experimental units (animals), which were conducted under tropical conditions, using hair sheep in growing and finishing phases and endowed of the following quantitative data for each animal: body weight (BW ), empty body weight (EBW ), average daily gain (ADG ), empty body gain (EBG ), heat production (HP ), metabolizable energy intake (MEI ), retained energy (RE ), metabolizable protein intake (MPI ) and body protein content. The regression equations generated were as follows: for Net Energy for maintenance, (NE m): ; for Net Energy for gain, (NE g): ; for Metabolizable Protein for maintenance,(MP m): MPI (g/day) = 24.8470 (±7.3646) + 560.28 (±99.6582) × EBG (kg/day); for Net Protein for gain, (NP g): . The NE m requirement was 0.246 MJ EBW?0.75 day?1. The metabolizable energy for maintenance requirement was 0.391 MJ EBW?0.75 day?1. Considering an ADG of 100 g, the NE g requirement ranged from 0.496 to 1.701 MJ/day for animals with BW ranging from 10 to 40 kg respectively. The efficiencies of use of the metabolizable energy for maintenance and gain were 0.63 and 0.36 respectively. The MP m requirement was 3.097 g EBW?0.75 day?1. Considering an ADG of 100 g, the NP g requirement ranged from 12.4 to 10.5 g/day for animals with BW ranging from 10 to 40 kg respectively. The total metabolizable energy and protein requirements were lower than those reported by the NRC and AFRC systems. Thus, our results support the hypothesis that nutrient requirements of hair sheep raised in tropical regions differ from wool sheep raised in temperate regions. Therefore, the use of the equations designed in this study is recommended. 相似文献
994.
Effect of resistant starch on the intestinal health of old dogs: fermentation products and histological features of the intestinal mucosa
下载免费PDF全文
![点击此处可从《Journal of animal physiology and animal nutrition》网站下载免费的PDF全文](/ch/ext_images/free.gif)
M. C. Peixoto É. M. Ribeiro A. P. J. Maria B. A. Loureiro L. G. di Santo T. C. Putarov F. N. Yoshitoshi G. T. Pereira L. R. M. Sá A. C. Carciofi 《Journal of animal physiology and animal nutrition》2018,102(1):e111-e121
The effects of resistant starch (RS) intake on nutrient digestibility, microbial fermentation products, faecal IgA, faecal pH, and histological features of the intestinal mucosa of old dogs were evaluated. The same formulation was extruded in two different conditions: one to obtain elevated starch cooking degree with low RS content (0.21%) and the other lower starch cooking with high RS content (1.46%). Eight geriatric Beagles (11.5 ± 0.38 years old) were fed each diet for 61 days in a crossover design. Food intake, nutrient digestibility, fermentation products, faecal pH, and faecal IgA were examined via variance analysis. Histological results of intestinal biopsies were assessed via Wilcoxon test for paired data. The morphometric characteristics of large intestine crypts were evaluated via paired t tests (p < .05). Protein, fat, and energy digestibilities were higher for the low‐RS diet (p < .05). Dogs receiving the high‐RS diet had lower faecal pH and higher values for propionate, butyrate, total volatile fatty acids, and lactate (p < .05). No differences between diets were found in the histological parameters of the gut mucosa, and only a tendency for deeper crypts in the descending colon was observed for dogs fed the high‐RS diet (p = .083). The intake of a corn‐based kibble diet manufactured with coarse ground raw material and low starch gelatinization to obtain 1.4% of RS affected microbial fermentation products and faecal pH and tended to increase crypt depth in the descending colon of old dogs. 相似文献
995.
Effect of sweet potato vines on performance parameters and some carcass characteristics of rabbits
下载免费PDF全文
![点击此处可从《Journal of animal physiology and animal nutrition》网站下载免费的PDF全文](/ch/ext_images/free.gif)
A. C. K. Klinger L. P. da Silva G. S. P. de Toledo B. Galarreta F. Goulart 《Journal of animal physiology and animal nutrition》2018,102(1):152-156
Conventional feedstuffs in Brazil are expensive, which has led to the search for less conventional cheaper and locally available feedstuffs. Thus, this study was carried out to determine the dietary effect of dry sweet potato vines (SPV) on the performance and some carcass characteristics of rabbits. A total of twenty‐seven weaned White New Zealand rabbits (14 male and 13 female) 35 days old with an average initial weight of 755 g were allocated into three treatments. Nine rabbits were assigned to each treatment in a completely randomized design. Three diets were formulated to similar protein and energy levels: 0SPV – diet without inclusion of dry sweet potato vines; 10SPV – diet with 10% alfalfa hay replaced by dry sweet potato vines; and 15SPV – diet with 15% of alfalfa hay replaced by dry sweet potato vines. The experiment lasted for 49 days during which data for feed intake and body weight were recorded. The daily feed intake ranged from 73.17 to 78.02 g; daily weight gain from 22.32 to 23.17 g; feed conversion ratio (FCR) from 3.16 to 3.49 and final live weight ranged from 1839.44 to 1880.55 g. None of the evaluated performance parameters as well as carcass weight, heart weight and percentages of fat and protein in meat were significantly affected by any of the tested dietary treatments. However, the liver weight was statistically lower in animals fed the diets containing 10% of SPV, mainly due to lower glucose content. Glycogen within the tissue, did not differ significantly among treatments. It was therefore concluded that up to 15% of SPV can successfully be included in the diet of rabbits as a cheaper replacement for alfalfa hay without adversely affecting performance. 相似文献
996.
Effect of gut stress induced by oxidized wheat gluten on the growth performance,gut morphology and oxidative states of broilers
下载免费PDF全文
![点击此处可从《Journal of animal physiology and animal nutrition》网站下载免费的PDF全文](/ch/ext_images/free.gif)
R. B. Liao H. J. Yan G. H. Liu S. Zhang W. H. Chang W. Liu C. H. Lin X. Y. Huang H. Y. Cai 《Journal of animal physiology and animal nutrition》2018,102(2):e849-e855
This study was to investigate the effect of oxidized wheat gluten (OG) on growth performance, gut morphology and its oxidative states of broilers. One hundred and eighty‐day‐old male broilers (10 chicks/pen) were randomly allocated into three dietary treatments: control diet (CON), diet with 8% wheat gluten (WG) and diet with 8% OG with six pens/treatment. Body weight (BW) (21 and 35 days) and average daily gain (ADG) (1–21 days and 22–35 days) decreased (p < .05) and feed conversion ratio (FCR) (1–21 days and 22–35 days) increased (p < .05) in OG treatment. Feed intake (FI) decreased (p < .05) in WG and OG treatments during 22–35 days. However, FI was not influenced by dietary treatments during 1–21 days (p > .05). The OG‐fed broilers had a lower faecal pH value (p < .05) and higher faecal moisture content (p < 05) at 14, 21, 28 and 35 days. Villus height, crypt depth and V/C value were not different (p > .05) among treatments at 21 and 35 days. Lipid peroxidation (LPO) (21 and 35 days) and malondialdehyde (MDA) (35 days) content in crop of OG treatment increased (p < .05). Oxidized glutathione (GSSG) (21 days), LPO (21 and 35 days) and MDA (21 and 35 days) content in ileum of OG treatment increased (p < .05). The reduced glutathione/oxidized glutathione (GSH/GSSG) (21 days) and (GSH) (35 days) in ileum of OG treatment decreased (p < .05). The present findings indicate that OG might be a stressor for broiler gut, which could induce oxidative stress both in crop and in ileum, and the diarrhoea as well. The growth performance of broiler was consequently depressed. 相似文献
997.
Effects of fat supplementation on plasma glucose,insulin and fatty acid analysis in ponies maintained on a forage‐based diet
下载免费PDF全文
![点击此处可从《Journal of animal physiology and animal nutrition》网站下载免费的PDF全文](/ch/ext_images/free.gif)
T. Williams B. Rude S. Liao C. Mochal‐King M. Nicodemus 《Journal of animal physiology and animal nutrition》2018,102(4):1069-1076
The objective of this study was to observe how fat incorporated into an equine forage‐based diet through supplementation altered levels of plasma glucose, insulin and fatty acids. Five Shetland/Hackney cross pony mares were fed alfalfa pellet diets top dressed with commercially available vegetable oil (blend of soya bean, canola and corn oils) at 0%, 5%, 10% or 15% of diet. Ponies were randomly assigned one of four diets to start, with a 14‐day adjustment period between transitioning to another one of the four diets. Ponies were gradually adapted to the new diet within the 14‐day period before a five‐day trial period. Each pony received all four diets by the end of the study. Each trial was a five‐day period with a three‐day sample collection. Blood samples for each collection week were taken 0, 30, 60, 90, 120, 150, 180, 210, 240 and 270 min and at 5, 6, 7, 8, 9 and 10 hr post‐feeding. Excess fat did not impact plasma glucose (p > .1), nor did it affect blood plasma insulin concentration. While there was no time alteration found for plasma fatty acid concentration (p > .1), C14:0 increased when ponies were fed 0% fat and C18:2 decreased when ponies were fed 0% fat. Plasma fatty acids (% of total FA) were higher in C18:0, C18:1, C18:2 and C20:1 in the added fat diets (p < .1). These findings suggest the amounts reported in this study of fat supplementation on a forage‐based diet did influence the fatty acid analysis within the pony, but did not negatively impact blood glucose and insulin concentrations. 相似文献
998.
K. S. Venturini M. F. Sarcinelli M. A. Baller T. C. Putarov E. B. Malheiros A. C. Carciofi 《Journal of animal physiology and animal nutrition》2018,102(4):1077-1087
Soya bean protein concentrate (SPC) with two particle sizes were evaluated on extrusion parameters, kibble formation, digestibility and palatability of dog foods. Eight diets were extruded: PBM—control diet based on poultry by‐product meal (PBM); GM—a diet in which corn gluten meal (GM) replaced 45% of the diet protein; cSPC15%, cSPC30% and cSPC45%—diets in which SPC of coarse particle size (600 μm) replaced 15%, 30% and 45% of the diet protein; and sSPC15%, sSPC30% and sSPC45%—diets in which SPC of small particle size (200 μm) replaced 15%, 30% and 45% of the diet protein. The digestibility of nutrients was evaluated for the PBM, GM, cSPC45% and sSPC45% diets, using six dogs per food. The PBM, GM and cSPC45% diets were compared for palatability. Data were submitted for analysis of variance, and the means were compared by polynomial contrasts or Tukey's test (p < .05). The cSPC increased the specific mechanical energy (SME) application, extrusion temperature and pressure linearly, resulting in lower kibble density and higher expansion and starch gelatinization (SG) (p < .01). When comparing the PBM, GM, cSPC45% and sSPC45% diets, higher SME, extrusion temperature and pressure, SG and kibble expansion were verified for the cSPC45% diet (p < .05). The DM, fat and crude protein digestibility were similar among diets. Faecal pH, ammonia and lactate did not differ, demonstrating that the removal of oligosaccharides and soluble non‐starch polysaccharides of SPC produces an ingredient with mostly non‐fermentable fibre. Dogs preferred the PBM to the GM diet (p < .05), but consumed the PBM and cSPC45% foods equally. In conclusion, SPC exhibited good extrusion functionality, favouring kibble expansion and SG, with high digestibility, similar to that of PBM. The removal of soluble compounds from soya beans resulted in an ingredient with low fermentable fibre content, which did not alter faecal formation or characteristics. 相似文献
999.
Amino acid profiles of rumen undegradable protein: a comparison between forages including cereal straws and alfalfa and their respective total mixed rations
下载免费PDF全文
![点击此处可从《Journal of animal physiology and animal nutrition》网站下载免费的PDF全文](/ch/ext_images/free.gif)
B. Wang L. S. Jiang J. X. Liu 《Journal of animal physiology and animal nutrition》2018,102(3):601-610
Optimizing the amino acid (AA) profile of rumen undegradable protein (RUP) can positively affect the amount of milk protein. This study was conducted to improve knowledge regarding the AA profile of rumen undegradable protein from corn stover, rice straw and alfalfa hay as well as the total mixed ratio diets (TMR) based on one of them as forage source [forage‐to‐concentrate ratio of 45:55 (30% of corn stover (CS), 30% of rice straw (RS), 23% of alfalfa hay (AH) and dry matter basis)]. The other ingredients in the three TMR diets were similar. The RUP of all the forages and diets was estimated by incubation for 16 hr in the rumen of three ruminally cannulated lactating cows. All residues were corrected for microbial colonization, which was necessary in determining the AA composition of RUP from feed samples using in situ method. Compared with their original AA composition, the AA pattern of forages and forage‐based diets changed drastically after rumen exposure. In addition, the extent of ruminal degradation of analysed AA was not constant among the forages. The greatest individual AA degradability of alfalfa hay and corn stover was Pro, but was His of rice straw. A remarkable difference was observed between microbial attachment corrected and uncorrected AA profiles of RUP, except for alfalfa hay and His in the three forages and TMR diets. The ruminal AA degradability of cereal straws was altered compared with alfalfa hay but not for the TMR diets. In summary, the AA composition of forages and TMR‐based diets changed significantly after ruminal exposure, indicating that the original AA profiles of the feed cannot represent its AA composition of RUP. The AA profile of RUP and ruminal AA degradability for corn stover and rice straw contributed to missing information in the field. 相似文献
1000.
Multimarker and rare variants genomewide association studies for bone weight in Simmental cattle
下载免费PDF全文
![点击此处可从《Zeitschrift für Tierzüchtung und Züchtungsbiologie》网站下载免费的PDF全文](/ch/ext_images/free.gif)
J. Miao X. Wang J. Bao S. Jin T. Chang J. Xia L. Yang B. Zhu L. Xu L. Zhang X. Gao Y. Chen J. Li H. Gao 《Zeitschrift für Tierzüchtung und Züchtungsbiologie》2018,135(3):159-169
Bone weight, defined as the total weight of the bones in all the forequarter and hindquarter joints, can reflect somebody conformation traits and skeletal diseases. To gain a better understanding of the genetic determinants of bone weight, we used a composite strategy including multimarker and rare‐marker association to perform genomewide association studies (GWAS) for that character in Simmental cattle. Our strategy consisted of three models: (i) A traditional linear mixed model (LMM) was applied (Q+K‐LMM); (ii) single nucleotide polymorphisms (SNPs) with p‐values less than .05 from the LMM were selected to undergo the least absolute shrinkage and selector operator (Lasso) in the second stage (LMM‐Lasso); (iii) genes containing two or more rare SNPs were examined by performing the sequence kernel association test (gene‐based SKAT). A total of 1,225 cattle were genotyped with an Illumina BovineHD BeadChip containing 770,000 SNPs. After the quality‐control procedures, 1,217 individuals with 608,696 common SNPs and 105,787 rare SNPs (with 0.001 < minor allele frequency [MAF] <0.05) remained in the sample for analysis. A traditional LMM successfully mapped three genes associated with bone weight, while LMM‐Lasso identified nine genes, which included all genes found by traditional LMM. Only a single gene, EPHB3, surpassed the significance threshold after Bonferroni correction in gene‐based SKAT. In conclusion, based on functional annotation and results from previous endeavours, we believe that LCORL, RIMS2, LAP3, PRKAR2B, CHSY1, MAP2K6 and EPHB3 are candidate genes for bone weight. In general, such a comprehensive strategy for GWAS may be useful for researchers seeking to probe the full genetic architecture underlying economic traits in livestock. 相似文献