全文获取类型
收费全文 | 21423篇 |
免费 | 281篇 |
国内免费 | 37篇 |
专业分类
林业 | 3844篇 |
农学 | 1553篇 |
基础科学 | 186篇 |
3616篇 | |
综合类 | 1235篇 |
农作物 | 2690篇 |
水产渔业 | 2183篇 |
畜牧兽医 | 3116篇 |
园艺 | 1181篇 |
植物保护 | 2137篇 |
出版年
2024年 | 4篇 |
2023年 | 35篇 |
2022年 | 117篇 |
2021年 | 184篇 |
2020年 | 131篇 |
2019年 | 167篇 |
2018年 | 2845篇 |
2017年 | 2801篇 |
2016年 | 1313篇 |
2015年 | 253篇 |
2014年 | 265篇 |
2013年 | 318篇 |
2012年 | 1138篇 |
2011年 | 2506篇 |
2010年 | 2315篇 |
2009年 | 1478篇 |
2008年 | 1637篇 |
2007年 | 1889篇 |
2006年 | 338篇 |
2005年 | 344篇 |
2004年 | 335篇 |
2003年 | 365篇 |
2002年 | 224篇 |
2001年 | 158篇 |
2000年 | 159篇 |
1999年 | 75篇 |
1998年 | 37篇 |
1997年 | 19篇 |
1996年 | 20篇 |
1995年 | 13篇 |
1994年 | 7篇 |
1993年 | 31篇 |
1992年 | 25篇 |
1991年 | 15篇 |
1990年 | 27篇 |
1989年 | 26篇 |
1988年 | 21篇 |
1987年 | 11篇 |
1986年 | 7篇 |
1985年 | 6篇 |
1984年 | 4篇 |
1983年 | 7篇 |
1980年 | 5篇 |
1978年 | 11篇 |
1977年 | 7篇 |
1974年 | 6篇 |
1972年 | 6篇 |
1969年 | 4篇 |
1968年 | 8篇 |
1967年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
71.
Cromwell GL Azain MJ Adeola O Baidoo SK Carter SD Crenshaw TD Kim SW Mahan DC Miller PS Shannon MC;North Central Coordinating Committee on Swine Nutrition 《Journal of animal science》2011,89(9):2801-2811
An experiment involving 560 crossbred pigs (28 replications of 4 to 6 pigs per pen) was conducted at 9 research stations to assess the effects of dietary concentrations of corn distillers dried grains with solubles (DDGS) on pig performance and belly firmness. Fortified corn-soybean meal diets containing 0, 15, 30, or 45% DDGS were fed in 3 phases from 33 to 121 kg of BW. A common source of DDGS containing 90.1% DM, 26.3% CP, 0.96% Lys, 0.18% Trp, 9.4% crude fat, 34.6% NDF, 0.03% Ca, and 0.86% P was used at each station. Diets were formulated to contain 0.83, 0.70, and 0.58% standardized ileal digestible (SID) Lys during the 3 phases with diets changed at 60 and 91 kg of BW, respectively. The DDGS replaced corn and soybean meal, and up to 0.172% Lys and 0.041% Trp were added to maintain constant SID concentrations of Lys and Trp in each phase. At each station, 2 pigs from each pen in 2 replications were killed and a midline backfat core was obtained for fatty acid analysis and iodine value. In most instances, there were differences among stations (P < 0.01), but the station × treatment interactions were few. Body weight gain was linearly reduced in pigs fed the greater amounts of DDGS (0 to 45%) during phase I (950, 964, 921, and 920 g/d; P < 0.01) and over the entire experimental period (944, 953, 924, and 915 g/d; P = 0.03), but ADFI (2.73, 2.76, 2.68, and 2.70 kg) and G:F (347, 347, 345, and 341 g/kg) were not affected (P = 0.15 and P = 0.33, respectively) during the entire test. Backfat depth was reduced (linear, P < 0.02) by increasing amounts of DDGS (22.5, 22.7, 21.4, and 21.6 mm), but LM area (47.4, 47.4, 46.1, and 45.4 cm(2)) was not affected (P = 0.16) by treatments. Estimated carcass fat-free lean was 51.9, 52.2, 52.4, and 52.1% for 0 to 45% DDGS, respectively (linear, P = 0.06). Flex measures obtained at 6 stations indicated less firm bellies as dietary DDGS increased (lateral flex: 11.9, 8.6, 8.4, and 6.6 cm; linear, P < 0.001; vertical flex: 26.1, 27.4, 28.2, and 28.7 cm; linear, P < 0.003). Saturated and monounsaturated fatty acid concentrations in subcutaneous fat decreased linearly (P < 0.001) and PUFA concentrations increased linearly (P < 0.001) with increasing DDGS in the diet. Iodine values in inner (61.1, 68.2, 74.7, and 82.2) and outer (67.9, 73.6, 79.6, and 85.8) backfat increased linearly (P < 0.001) as DDGS in the diet increased. In this study, feeding diets with 30 or 45% DDGS did not have major effects on growth performance, but resulted in softer bellies. Regression analysis indicated that iodine values increased 4.3 units for every 10 percentage unit inclusion of DDGS in the diet. 相似文献
72.
Na-Hyun Kim Thomas Ciesielski Jung H. Kim Ji-Young Yhee Keum-Soon Im Hae-Mi Nam Il-Hwan Kim Jong-Hyuk Kim Jung-Hyang Sur 《The Canadian veterinary journal. La revue veterinaire canadienne》2012,53(5):559-564
This report describes a primary central nervous system B-cell lymphoma in a 3-year-old intact female Maltese dog. Canine primary central nervous system lymphomas constitute about 4% of all intracranial primary neoplasms, but comprehensive histopathologic classifications have rarely been carried out. This is the first report of this disease in a young adult dog. 相似文献
73.
Ferreira SR Araújo JV Braga FR Araujo JM Carvalho RO Silva AR Frassy LN Freitas LG 《Tropical animal health and production》2011,43(3):639-642
The ovicidal effect of the nematophagous fungus Pochonia chlamydosporia on eggs of Ascaris suum was tested under laboratory conditions. A. suum eggs were plated on 2% water–agar with seven fungal isolates (Isol. 5, Isol. 31, Isol. 1, VC1, Isol. 12, Isol. 22 and VC4)
and control without fungus. After 5, 7, 10, 14, 15 and 21 days of incubation, approximately 100 eggs were removed from the
plates and classified according to the following parameters: type 1, biochemical and physiological effect without morphological
damage to the eggshell, type 2, lytic effect with morphological alteration of the eggshell and embryo and type 3, lytic effect
with morphological alteration of eggshell and embryo showing hyphal penetration and internal egg colonization. The isolates
effectively destroyed A. suum eggs and all types of effects were observed during the experiment. There was no variation in ovicidal capacity (type 3 effect)
among the isolates (p > 0.05) throughout the experiment. After 21 days, isolate 5 showed the highest percentages of type 3 effect (58.33%). The
results indicated that P. chlamydosporia (Isol. 5, Isol. 31, Isol. 1, VC1, Isol. 12, Isol. 22 and VC4) can destroy A. suum eggs and is, therefore, a potential biological control agent of nematodes. 相似文献
74.
Circulating oxidative stress status in dromedary camels infested with sarcoptic mange 总被引:2,自引:0,他引:2
Oxidative stress is an imbalance between radical-generating and radical-scavenging activity, resulting in oxidation products
and tissue damage. This study was aimed to evaluate the status of oxidative stress indices in blood of camels naturally infested
with S. scabiei. Forty-seven male camels (Camelus dromedaries) were divided according to the extent of the infested area with Sarcoptes scabiei into four groups, mild (MID, n = 12), moderate (MOD, n = 10), severely infested (SEV, n = 10) and healthy control group (n = 15). Blood was used for determination of red cell count (RBC), hemoglobin (Hb), packed cell volume (PCV), serum nitric
oxide (NO•, a free radical), ascorbate and albumin concentrations, and erythrocytic values of malondialdehyde (MDA, a marker of lipid
peroxidation), protein carbonyls (PC, an indicator of protein oxidation), glutathione (GSH) superoxide dismutase (SOD) and
catalase (CAT). Decreased levels (P < 0.05) of RBC, Hb, PCV, albumin and ascorbate were noticed in MOD and SEV compared to controls with the lowest values (P < 0.05) in SEV except for ascorbate, where MOD did not differ from SEV. Compared to controls, NO• gradually increased (P < 0.05) in MID followed by MOD and SEV, whereas MDA and PC were higher (P < 0.05) in MOD and SEV. PC was higher (P < 0.05) in MOD than SEV. In addition, the antioxidants GSH, SOD and CAT were higher (P < 0.05) in MID and lower (P < 0.05) in MOD and SEV compared to controls. GSH was lower (P < 0.05) in SEV compared to MOD. Besides, Hb was negatively correlated with NO• (r = −0.68, P < 0.001), MDA (r = −0.53, P < 0.001) and PC (r = −0.73, P < 0.001). In conclusion, dromedary sarcoptosis is accompanied by a state of oxidative stress process, which increased by
increasing the area of infestation, and may contribute to the pathogenesis of the disease. 相似文献
75.
Kim MS Yoo JH Seo KM Jeong SM 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2007,69(11):1163-1165
The effects of electroacupuncture (EA) on intraocular pressure (IOP) and hemodynamic parameters were evaluated in isoflurane anesthetized 10 (5 males, 5 females) normal mongrel dogs (8.1-9.8 kg, 6-8 years old). After determination of baseline IOP and hemodynamic parameters (cardiac index, systolic arterial pressure, diastolic arterial pressure, heart rate and systemic vascular resistance index), EA was applied at 3 acupoints (LI-4, LIV-3 and GB-37) for 20 min. After the EA treatment, IOP was significantly decreased in the both eyes (p<0.05). However, there were not significant differences in hemodynamic parameters between those of before and after EA treatment. From these results, the EA treatment at LI-4, LIV-3 and GB-37 would be considered one of the valuable methods for the IOP treatment in dogs. 相似文献
76.
Choi US Jeong SM Kang MS Jung IS Kim DY Lee CW 《Veterinary clinical pathology / American Society for Veterinary Clinical Pathology》2004,33(1):47-49
Abstract: An 18-month-old male Doberman Pinscher was referred to the Veterinary Medical Teaching Hospital of the College of Veterinary Medicine for an erythemic nodular mass on the right forelimb. The mass was diagnosed as cutaneous lymphoma, based on cytologic examination of a mass aspirate and histopathology. Using immunohistochemistry the neoplastic cells were positive for CD3 but negative for CD79a, E-cadherin, and pancytokeratin, confirming their origin as T lymphocytes. No tumor recurrence was noted 18 months after surgery. To our knowledge, this is the first report of a solitary nodular form of cutaneous lymphoma in a young dog. 相似文献
77.
Zamoto A Tsuji M Wei Q Cho SH Shin EH Kim TS Leonova GN Hagiwara K Asakawa M Kariwa H Takashima I Ishihara C 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2004,66(7):785-792
We previously reported that small wild rodents in Japan harbor two types of novel Babesia microti-like parasites (designated as Hobetsu and Kobe types), but not the type commonly found in the northeastern United States (U.S. type) where human babesiosis is endemic. To determine whether these new types of parasites are distributed in places surrounding Japan, an epizootiologic survey was undertaken in three geographically distant areas in northeastern Eurasia; South Korea, Vladivostok in Russia, and Xinjiang in China. Blood samples were collected from a total of 387 animals comprising 24 species. DNAs extracted from the samples were tested by nested PCR targeting babesial nuclear small-subunit rRNA gene (rDNA), which revealed that small rodents harboring B. microti exist in all three survey areas. Sequence analysis showed that all PCR-positive samples had rDNA sequences virtually identical to that of U.S.-type B. microti. However, when beta-tubulin gene sequences were compared, evident geographic variations were seen. By use of primers specific for each of the beta-tubulin genes of Kobe-, Hobetsu-, and U.S.-type parasites, a type-specific PCR was developed. Parasite with Hobetsu- or Kobe-type sequence was not detected from any of the three survey areas. These findings suggest that U.S.-type B. microti is widely distributed among small wild mammals in temperate zones of not only North America, but also Eurasia, whereas that Hobetsu- and Kobe-type parasites may be uniquely distributed in Japan. 相似文献
78.
Genotypic prevalence of the adhesin involved in diffuse adherence in Escherichia coli isolates in pre-weaned pigs with diarrhoea in Korea 总被引:1,自引:0,他引:1
Ha SK Choi C Jung K Kim J Han DU Ha Y Lee SD Kim SH Chae C 《Journal of veterinary medicine. B, Infectious diseases and veterinary public health》2004,51(4):166-168
A total of 1002 Escherichia coli strains isolated from pre-weaned pigs with diarrhoea on 1114 swine farms were screened for the presence of the adhesin involved in diffuse adherence (AIDA) gene by polymerase chain reaction (PCR). Escherichia coli isolates that carried AIDA genes were also tested by PCR for the detection of five fimbriae (F4, F5, F6, F18 and F41), heat-stable (STa, STb) and heat-labile (LT) enterotoxin, enteroaggregative E. coli heat-stable enterotoxin 1 (EAST1), and Shiga toxin 2 oedema disease (Stx2e) genes. Twenty-three (2.3%) of the 1002 E. coli isolates carried the gene for AIDA. Among 23 isolates shown to carry genes for AIDA, three carried the AIDA gene as the only shown virulence factor. Other isolates carried other virulence factor genes in addition to AIDA. Four isolates carried genes for at least one of the fimbrial adhesins and enterotoxins. Sixteen isolates carried genes for enterotoxins only. The AIDA may represent an additional virulence determinant in pre-weaned pigs with diarrhoea. 相似文献
79.
Tatsuya Nakayama Michio Jinnai Ryuji Kawahara Khong Thi Diep Nguyen Nam Thang Tran Thi Hoa Le Kieu Hanh Pham Ngoc Khai Yoshinori Sumimura Yoshimasa Yamamoto 《Tropical animal health and production》2017,49(1):31-37
Reports of livestock infections with extended-spectrum beta-lactamase-producing Escherichia coli (ESBL-E) are increasing. Based on interviews conducted over a 6-month period, we found that veterinarians in the Vietnamese province of Thai Binh prefer to prescribe colistin-based drugs (CBD) in chicken farms. We aimed to clarify whether CBD use selects for strains of colistin-resistant ESBL-E. With the cooperation of seven local households, we detected ESBL-E in chickens’ feces after treating chickens with CBD. Phylogenetic groupings and the presence of CTX-M/AmpC genes were determined, and the multi-antibiotic susceptibility of isolates was analyzed. Our results showed that ESBL-E presented in seven chickens’ feces from two households. Seventy-two percent of ESBL-E isolates harbored CTX-M9 and the phylogenetic group A; the colistin minimum inhibitory concentration (MIC) of all isolated ESBL-E ranged from 0.064 to 1 μg mL?1. Moreover, ESBL-E isolates were used to experimentally select for colistin resistance, and the effect of commercial CBD on ESBL-E was investigated. The results showed that an ESBL-E strain with a colistin MIC of 4 μg mL?1 was able to grow in media with CBD. Although CBD treatment was effective, in vitro experiments demonstrated that ESBL-E can easily acquire colistin resistance. Therefore, restrictions on colistin use are necessary to prevent the emergence of colistin-resistant bacteria. 相似文献
80.