全文获取类型
收费全文 | 9549篇 |
免费 | 3758篇 |
国内免费 | 11篇 |
专业分类
林业 | 372篇 |
农学 | 738篇 |
基础科学 | 39篇 |
1906篇 | |
综合类 | 394篇 |
农作物 | 218篇 |
水产渔业 | 2752篇 |
畜牧兽医 | 5235篇 |
园艺 | 69篇 |
植物保护 | 1595篇 |
出版年
2023年 | 56篇 |
2022年 | 25篇 |
2021年 | 138篇 |
2020年 | 497篇 |
2019年 | 1101篇 |
2018年 | 1050篇 |
2017年 | 1081篇 |
2016年 | 1050篇 |
2015年 | 935篇 |
2014年 | 924篇 |
2013年 | 1113篇 |
2012年 | 616篇 |
2011年 | 670篇 |
2010年 | 764篇 |
2009年 | 403篇 |
2008年 | 419篇 |
2007年 | 250篇 |
2006年 | 257篇 |
2005年 | 242篇 |
2004年 | 199篇 |
2003年 | 188篇 |
2002年 | 159篇 |
2001年 | 212篇 |
2000年 | 247篇 |
1999年 | 101篇 |
1998年 | 46篇 |
1997年 | 55篇 |
1996年 | 40篇 |
1995年 | 35篇 |
1994年 | 27篇 |
1993年 | 22篇 |
1992年 | 37篇 |
1991年 | 42篇 |
1990年 | 42篇 |
1989年 | 25篇 |
1988年 | 29篇 |
1987年 | 19篇 |
1986年 | 20篇 |
1985年 | 16篇 |
1984年 | 11篇 |
1983年 | 13篇 |
1982年 | 7篇 |
1979年 | 9篇 |
1978年 | 10篇 |
1977年 | 5篇 |
1970年 | 7篇 |
1966年 | 7篇 |
1903年 | 4篇 |
1893年 | 4篇 |
1892年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
131.
Plantago ovata in broiler chicken nutrition: Performance,carcass criteria,intestinal morphology,immunity, and intestinal bacterial population 下载免费PDF全文
A. Divani F. Bagherzadeh‐Kasmani M. Mehri 《Journal of animal physiology and animal nutrition》2018,102(1):e353-e363
In this experiment, the effect of dietary Plantago ovata (PO) on performance, carcass criteria, intestinal morphology, immunity, and intestinal bacterial population of broiler chickens was evaluated. A total of 250 one‐day‐old male broiler chicks (Ross 308) were randomly assigned to five treatments containing 0, 5, 10, 15, or 20 g/kg of PO with five replicate pens and 10 birds in each replicate. Dietary PO increased body weight gain and decreased feed conversion ratio in the finisher period, improving the performance index (p < .05). Dietary treatments had no effects on carcass criteria, but breast meat percentage showed an increasing trend with incremental levels of PO in the diet (p = .069). The length of small intestine, especially jejunum section, as well as the villus height, villus width, villus area, and goblet cell numbers were significantly increased with supplemental PO (p < .05). Humoral and cellular immunity parameters, and oxidation stability of meat were improved due to use of dietary PO (p < .05). Dietary PO decreased the CFU of Escherichia coli, whereas the Lactobacilli population was increased (p = .001). Broken‐line regression revealed that dietary PO at the rate of 10 g/kg may results in the best performance in broiler chickens. This study showed that PO at the level of 10 g/kg could be considered as a beneficial feed additive in broiler diet. 相似文献
132.
M. K. Shikh Alsook N. Antoine J. Piret N. Moula V. Busoni J.‐M. Denoix A. Gabriel 《Anatomia, histologia, embryologia》2013,42(6):461-470
The third interosseous muscle (suspensory ligament, TIOM) is composed of connective tissue (CT) with a variable proportion of muscle (MT) and adipose tissue (AT). The aim of our study is to quantify the CT, MT and AT within the body and the branches of right thoracic and pelvic limbs TIOM in sound horses to determine whether there are differences in CT, MT and AT between age, sex, limbs and levels. Right limbs from 11 sound horses were collected. Samples from 6 levels of the TIOM were embedded in paraffin or in Tissue‐Tek®. Most of the paraffin sections were shredded. Using the cryosection, some artefacts appeared. Cryoprotection was carried out, which produced the best results. Hematoxylin–phloxine–saffron and Hematoxylin–eosin gave a good contrast of colours between the tissues observed allowing the use of an image analysis programme to calculate percentage of each tissue within the TIOM. The percentage of MT and AT decreased significantly (P < 0.0001), whereas the percentage of CT increased significantly (P < 0.0001) with age and when descending from the proximal to the distal level of the TIOM. The percentage of MT was significantly higher (P < 0.0001) in females than males, while the percentage of CT was significantly higher (P < 0.0001) in males than females. The percentage of AT was significantly higher (P = 0.0278) in pelvic limbs than in thoracic limbs. These results confirm the variation in tissue composition within the TIOM of sound horses. 相似文献
133.
The vertebral heart score (VHS) measurement is commonly used to provide a more objective measurement of cardiomegaly in canines. However, several studies have shown significant breed variations from the value previously established by Buchanan and Bücheler (9.7 ± 0.5). This study describes VHS measurements in Pug, Pomeranian, Yorkshire Terrier, Dachshund, Bulldog, Shih Tzu, Lhasa Apso, and Boston Terrier dog breeds. Dogs with two or three view thoracic radiographs, no subjective radiographic evidence of cardiomegaly, and no physical examination findings of heart murmurs or gallop rhythms were included in the study. The Pug, Pomeranian, Bulldog, and Boston Terrier groups were found to have a VHS significantly greater than 9.7 ± 0.5 (P < 0.00001, P = 0.0014, P < 0.0001, P < 0.00001, respectively). Body condition score (BCS) was found to have a significant effect on the VHS of Lhasa Apso group. Anomalous vertebrae in the thoracic column were associated with a significant increase in VHS of the Bulldog (P = 0.028) and Boston Terrier (P = 0.0004) groups. Thoracic depth to width ratio did not have a significant effect on VHS. 相似文献
134.
A. Kovačić I. Listeš C. Vučica L. Kozačinski I. Tripković K. Šiško‐Kraljević 《Zoonoses and public health》2013,60(4):269-276
Consumption of poultry contaminated with Campylobacter jejuni has been recognized worldwide as the leading cause of campylobacteriosis. Therefore, the aim of our study was to investigate the prevalence and genotype diversity of Campylobacter jejuni in poultry meat intended for consumption in Split and Dalmatia County, which is the second biggest County in Croatia. Furthermore, we also wanted to discover possibly stable clones of C. jejuni appearing in different samples and periods of time, which would indicate their ability to persist in or adapt to poultry. In the period from March 2008 until June 2010, 834 samples of poultry from various sources were examined using a surface swab technique. Isolation of C. jejuni was performed by Preston broth and Karmali agar. Identification of the isolates was carried out using biochemical tests. C. jejuni was found in 84 of 574 chicken samples (14.6%) and in nine of 260 samples of turkey (3.5%). Pulse‐field gel electrophoresis (PFGE) was used to analyse 61 obtained isolates using SmaI and KpnI. Of 22 different macrorestriction profiles (MRP) that were found, five were detected in poultry from both different locations and periods of time. Samples from 11 locations were found to be contaminated with more than two different genotypes of C. jejuni. Interestingly, the same MRP were found both in poultry declared to be of domestic origin and in the poultry imported from abroad. The prevalence of C. jejuni in poultry samples was in accordance with previously reported results. Genotypic analysis indicated that the population of C. jejuni in Split and Dalmatia County was diverse and that multiple strains of C. jejuni could be found in the same poultry samples. Furthermore, the same genotypes were identified from the samples obtained from different locations and periods of time, which could support the theory of a global existence of certain MRP that are able to persist in or adapt to poultry. 相似文献
135.
C.‐C. Gelfert M. Passfeld A. Löptien N. Montag W. Baumgartner R. Staufenbiel 《The Veterinary quarterly》2013,33(4):130-139
Summary This study was initiated to investigate the influence of a daily dose of anionic salts (AS) above the valid upper limit at present on metabolism of dairy cows. Eleven non‐pregnant and non‐lactating Holstein‐Friesian crossbred cows with a permanent rumen cannula were used in a study with a controlled feeding design. The initial daily dose was 2500 meq/day, which resulted in a Dietary Cation Anion Difference (DCAD) of ‐211 meq/kg dry matter. Every seven days, the daily dose was raised by 500 meq. If a cow stopped eating, the application of AS was stopped and these cows were monitored over the next seven days. On day 30 another batch of hay, having the same DCAD but higher concentrations of minerals and energy, was fed. Blood and urine samples were taken to monitor acid‐base balance and calcium concentrations. Acid‐base balance was strongly influenced by AS. Blood pH dropped steadily and reached values around 7.23. Urine pH dropped quickly below 6 and remained at that level regardless of the increased dosage of AS. Net acid base excretion (NABE) fell continuously with the increase of the dosage of AS and reached values below ‐200 mmol/l. Calcium concentrations in the serum were nearly stable, but those in urine increased sharply and remained on an elevated level with increasing doses of AS. A few days before the individual cow's refusal of feed intake, calcium excretion in urine decreased. The majority of cows stopped eating while consuming a diet containing 3500 to 4000 meq AS except two animals who consumed up to 6000 meq/day AS but they received the better hay in the second half of the treatment period. In this time pH in blood increased slowly. NABE remained stable on a low level at ‐100 mmol/l. The results showed that with an increasing amount of AS fed the risk of clinical acidosis increased. The decreasing urine concentrations of calcium indicate a breakdown of the compensation capability of the single cow. Besides the dose of AS fed, the quality of the feed stuff might be another factor concerning the tolerance of cows against AS. 相似文献
136.
Effect of injecting amino acids into the egg on embryonic and subsequent growth in the domestic fowl
W. K. Al‐Murrani 《British poultry science》1982,23(2):171-174
1. The growing embryo uses about 1% of the total protein available in the egg during the first week of incubation.
2. Injecting the growing embryo with amino acids equivalent to the amount of protein used resulted in higher weight of chicks at all stages up to 56 d. 相似文献
137.
Immunogenic properties of a bovine herpesvirus-1 (BHV-1) recombinant expressing major pseudorabies virus (PrV) glycoproteins in combination 总被引:1,自引:0,他引:1
Ikeda Y Shibata I Xuan X Matsumoto Y Otsuka H 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2000,62(8):849-859
A recombinant bovine herpesvirus type 1 (BHV-1), designated BHV-1/TF17-1, which expresses pseudorabies virus (PrV) glycoproteins gB, gC, gD, gE and gI in combination was constructed. To test the protective immunity, 10 mice were inoculated with BHV-1/TF17-1 and three weeks later 10 mice were intraperitoneally (i.p.) challenged with 20 LD50 virulent PrV (YS-81). BHV-1/TF17-1 protected all the mice from the PrV lethal challenge while all the control mice died in around 3 days. Mice vaccinated with BHV-1/TF17-1 acquired high PrV-neutralizing antibody titers and demonstrated strong delayed type hypersensitivity responses and moderate in vitro lymphocyte proliferative responses to PrV antigen. Since the major PrV glycoproteins were integrated into virions (probably into viral envelope), BHV-1/17-1 was neutralized with anti-PrV antiserum. However, the susceptibility of BHV-1/TF17-1 to anti-PrV antiserum is 2- to 4-fold lower than that of PrV vaccine lines. Our results demonstrated the possibility of BHV-1/17-1 as a vaccine to protect piglets from Audjesky's disease where maternal antibodies against PrV interfere attenuated live PrV vaccines. 相似文献
138.
A. Thaler‐Neto R. Fries G. Thaller 《Zeitschrift für Tierzüchtung und Züchtungsbiologie》2000,117(3):153-167
The risk ratio (λR) is defined as ‘the recurrence risk for a relative of an affected individual divided by the prevalence in the general population’ and is considered as the most important parameter when designing mapping experiments for diseases in humans. In this paper, the risk ratio was introduced as a parameter to genetically characterize complex binary traits such as mastitis in cattle. Simulations were applied to evaluate the properties of λR under different genetic models (monogenic, digenic, polygenic and mixed models) and in dependency of their parameters for a design consisting of unbalanced halfsib families typically found in dairy cattle. Population prevalences of the simulated data ranged from 5 to 40% and λR was estimated on a phenotypic level. In the discrete loci models complexity of the traits was introduced through different levels of penetrance and the proportions of phenocopies within each genetic background. The risk ratio and the power to reject the null hypothesis of independent halfsibs (λR=1) were influenced by the prevalence in all genetic models chosen. Absolute values for λR were higher for lower prevalences, for example, λR=2.77 and 1.62 for a pure monogenic recessive model with 5 and 20% prevalence, respectively, whereas the power decreases in the case of lower prevalences. For all the prevalences investigated, higher risk ratios were found for discrete loci models compared with the polygenic models, with higher values for the monogenic relative to the digenic models in general. For the mixed models, λR was intermediate between the polygenic and discrete loci models. Genes with dominant relative to recessive inheritance for susceptibility caused higher risk ratios in monogenic and mixed models, for example, λR=5.16 and 2.77 for a pure monogenic model with 5% prevalence. In the discrete loci models, λR decreased with lower penetrance and a higher proportion of phenocopies. Risk ratios increased with the heritability in the polygenic and in addition with the effect of the major gene in mixed models. Consistent patterns of risk ratios were observed under the analysed genetic models and parameters, which indicate that the risk ratio is a parameter well suited to genetically characterize binary traits in unbalanced halfsib families. 相似文献
139.
Qiao GH Zhou XH Li Y Zhang HS Li JH Wang CM Lu Y 《Journal of animal physiology and animal nutrition》2012,96(5):930-938
Two experiments were carried out in this study. Experiment 1 was conducted to examine the effects of several supplemental Chinese herbs on antioxidant function and slaughtered body weight in sheep. Results indicated that Fructus Ligustri Lucidi supplementation improved the blood antioxidant function [higher concentration of glutathione reductase (GR), superoxide dismutase and lower concentration of malondialdehyde] and slaughtered body weight in sheep (p < 0.05). Experiment 2 was conducted to investigate the effect of Fructus Ligustri Lucidi extract (FLLE) on rumen fermentation and nutrient digestibility in sheep. Four levels of FLLE treatments, i.e. 0, 100, 300 and 500 mg/kg dry matter (DM), were used in this part. Addition of FLLE at 300 or 500 mg/kg DM increased total volatile fatty acid (VFA) concentration and propionate proportion, decreased ammonia-N concentration in the ruminal fluid, reduced blood urea nitrogen concentration at 2, 4, 6 and 8 h after morning feeding (p < 0.05). Addition of FLLE at all dosages had no effect on ruminal pH value and acetate concentration at all sampling time points in sheep (p > 0.05). Dynamic degradation coefficient c of maize DM was significantly increased by supplementing FLLE at 300 or 500 mg/kg DM (p < 0.05). Fructus Ligustri Lucidi extract addition had no effect on degradation coefficients a, b, c of DM and nitrogen of soybean meal; a, b of maize DM; a, b, c of maize nitrogen; and a, b, c of neutral detergent fibre (NDF) and acid detergent fibre (ADF) of Chinese wildrye (p > 0.05). Addition of FLLE at 300 or 500 mg/kg DM increased DM and organic matter digestibility of diet (p < 0.05). Fructus Ligustri Lucidi extract addition had no effect on digestibility of diet's NDF, ADF and crude protein (p > 0.05). From the aforementioned results, it is indicated that FLLE improved antioxidant status and slaughtered body weight. Fructus Ligustri Lucidi extract addition has capability to modulate rumen fermentation, increase the maize degradation rate, total volatile fatty acid concentration and propionate proportion in sheep. 相似文献
140.
Hafnia alvei is considered an opportunistic pathogen of animal and humans, affecting a wide range of homeothermic and poikilothermic hosts with different body temperatures. In this work, H. alvei strains isolated from different sources were studied with regard to their capacity to form biofilms under different environmental conditions. Strain, growth phase, temperature and culture media dependent changes of biofilm formation were semiquantitatively monitored using a microtiter plate method. Our study shows that all strains used could form biofilms in vitro, and that biofilm formation increases dramatically during growth at 25 degrees C but not at 37 degrees C, and decreases at both temperatures in presence of glucose. At 16 degrees C only one strain isolated from a lizard was able to form a dense biofilm showing that the ability to form biofilms in this species is regulated by environmental factors and is also strain specific. 相似文献