全文获取类型
收费全文 | 2660篇 |
免费 | 140篇 |
专业分类
林业 | 235篇 |
农学 | 304篇 |
基础科学 | 31篇 |
614篇 | |
综合类 | 119篇 |
农作物 | 203篇 |
水产渔业 | 303篇 |
畜牧兽医 | 684篇 |
园艺 | 72篇 |
植物保护 | 235篇 |
出版年
2023年 | 36篇 |
2022年 | 75篇 |
2021年 | 85篇 |
2020年 | 102篇 |
2019年 | 130篇 |
2018年 | 158篇 |
2017年 | 152篇 |
2016年 | 124篇 |
2015年 | 87篇 |
2014年 | 121篇 |
2013年 | 243篇 |
2012年 | 185篇 |
2011年 | 160篇 |
2010年 | 140篇 |
2009年 | 99篇 |
2008年 | 110篇 |
2007年 | 104篇 |
2006年 | 89篇 |
2005年 | 67篇 |
2004年 | 53篇 |
2003年 | 48篇 |
2002年 | 35篇 |
2001年 | 48篇 |
2000年 | 37篇 |
1999年 | 28篇 |
1998年 | 21篇 |
1997年 | 16篇 |
1996年 | 10篇 |
1995年 | 6篇 |
1994年 | 9篇 |
1993年 | 6篇 |
1992年 | 12篇 |
1991年 | 14篇 |
1990年 | 15篇 |
1989年 | 10篇 |
1988年 | 12篇 |
1987年 | 14篇 |
1986年 | 8篇 |
1985年 | 8篇 |
1984年 | 8篇 |
1983年 | 9篇 |
1982年 | 6篇 |
1981年 | 9篇 |
1979年 | 16篇 |
1976年 | 6篇 |
1974年 | 8篇 |
1973年 | 11篇 |
1971年 | 7篇 |
1969年 | 7篇 |
1968年 | 5篇 |
排序方式: 共有2800条查询结果,搜索用时 15 毫秒
21.
The present study highlights the effective removal of Cu (II) ions from synthetic solution using bacteria such as B. subtilis, P. aeruginosa and E. cloacae. Batch biosorption studies show that the biosorption of B. subtilis is effective when the concentration ranges from 25-200 mg L(-1). Biomass dosage, pH and the initial metal ion concentration have a profound effect on the biosorption process and this is reported in this study. In order to understand the nature of the biosorption process, Langmuir and Freundlich isotherm models were applied. Pseudo first and second order models were used to study the biosorption kinetics. The results show that these bacterial strains are very much suitable for the removal of Cu (II) ions. Being cost effective and efficient in toxic metal ion removal, these bacteria can be used on a large scale. 相似文献
22.
Gowane G. R. Akram Najif Prince L. L. L. Prakash Ved Kumar Arun 《Tropical animal health and production》2017,49(4):867-873
Tropical Animal Health and Production - Enterotoxaemia (ET) is a fatal enteric disease of small ruminants attributable to a toxigenic type of Clostridium perfringens. The key strategy for... 相似文献
23.
Effects of activation methods on DNA synthesis and development of parthenogenetic porcine embryos 总被引:1,自引:0,他引:1
Ock SA Kwack DO Mohana Kumar B Han J Kim SW Rho GJ 《Reproduction in domestic animals》2011,46(6):1082-1089
This study investigated the timing of DNA synthesis and patterns of pronuclear (PN) formation during the first cell cycle, and its influence on developmental competence, velocity and proliferation index of porcine parthenote blastocysts produced by different activation treatments. Oocytes were activated as follows: electrical stimulation (EST), EST combined with 7.5 μg/ml cytochalasin B (EST + CCB), 10 μg/ml cycloheximide (EST + CHX) and 1.9 mm 6-dimethylaminopurine (EST + 6-DMAP) for 3 h. DNA synthesis and PN formation were evaluated using 1 mm 5'bromo-2'deoxy-uridne (BrdU) at 2 h intervals from 1 to 13 h or 5 to 13 h of post-activation (hpa), respectively. In EST, DNA synthesis started at 3 hpa, reached the peak at 11 hpa and decreased at 13 hpa. Treatment with 6-DMAP resulted in an early increase of DNA synthesis at 3 hpa, whereas CCB delayed DNA synthesis for 2 h. In EST and EST + 6-DMAP, most of the eggs showed 1PN, whereas, incidence of 2PN in EST + CCB was higher than 1PN. EST + CHX was observed with 1PN, 2PN and multiple PN. Blastocyst rate in EST + CCB and EST + 6-DMAP were significantly (p<0.05) higher than EST + CHX. But, the developmental velocity was not different among groups. Proliferation index of blastocysts, as indicated the number of blastomere at S-phase of the cell cycle was low in all groups. In conclusion, CCB, CHX and 6-DMAP used for producing porcine parthenogenetic embryos induced different onset of DNA synthesis and PN, but they did not affect the subsequent embryo development. 相似文献
24.
25.
26.
TREATMENT OF DIAPHRAGMATIC HERNIA IN BUFFALOES 总被引:2,自引:0,他引:2
J. Singh B. Prasad R. Kumar R. N. Kohli S. S. Rathor 《Australian veterinary journal》1977,53(10):473-475
The surgical treatment of diaphragmatic hernia attempted on 19 lactating buffaloes is described. Thirteen cases recovered uneventfully, 1 recovered after developing brisket oedema and 5 died, 3 during surgery and 2 postoperatively. The desired depth of anaesthesia was achieved by the administration of 6% chloral hydrate followed by 5% thiopentone sodium. A postxiphoid approach and the use of a continuous lock stitch suture were preferred to repair the vent in the diaphragm. Pre- and post-operative use of hydrocortisones and fluids and sufficient tissue oxygenation by controlled positive pressure respiration are believed to be keys to the success of the treatment adopted. 相似文献
27.
28.
Kumar N Sharma AK Sharma AK Kumar S 《Journal of veterinary medicine. A, Physiology, pathology, clinical medicine》2002,49(5):269-276
The efficacy of carbon fibres and plasma-preserved tendon allografts for gap repair in the superficial digital flexor tendon in the mid-metatarsal region was evaluated in 12 crossbred calves. Experimental tenectomies were performed, followed by implantation of carbon fibres in group I (12 legs) and plasma-preserved tendon allografts in group II (12 legs). Gross observations in group I showed filling of the defect with granulation tissue with more vascularity on day 7, which was less prominent at day 14. On day 30, the neotendon formed was slightly thicker and comparable to normal tendon in appearance and texture. On day 90, it exhibited all the characteristics of a fully developed tendon. Whereas, in group II increased vascularity at the site and encapsulation of the graft with connective tissue in early periods was observed. The gap between graft and host was filled with fibrous connective tissue. Peritendinous adhesions were maximum on day 7 which were gradually reduced in both groups. Microscopically, an acute inflammatory reaction in the periphery of carbon fibres was observed on day 7. Immature fibroblasts were arranged in a haphazard pattern at this stage. By day 14, numerous newly formed capillaries and comparatively more mature fibroblasts were present in between and around the carbon fibres which were aligning parallel to the longitudinal axis of the tendon. By day 30 the healing tissue exhibited longitudinal orientation of collagen fibres and was at a more advance stage of maturation. By day 90, the neotendon formed simulated the picture of normal tendon. In the grafted tendon group, there was normal healing tissue at the functional sites between host and grafted tendon. The fibroblastic activity appeared to be both extrinsic and intrinsic in origin. The connective tissue had invaded the graft to a variable distance and there was resorption of graft which was replaced by newly formed connective tissue on day 90. Scanning electron microscopic observation revealed formation of neotendon between carbon fibre strands, resulting in thickening of the implant. In later stages parallel collagen fibres resembling normal tendon were observed in both groups. 相似文献
29.
Kirker-Head CA Chandna VK Agarwal RK Morris EA Tidwell A O'Callaghan MW Rand W Kumar MS 《American journal of veterinary research》2000,61(6):714-718
OBJECTIVE: To correlate substance P content of synovial fluid with prostaglandin E2 content, radiographic evidence of joint abnormality, and anatomic location of the joint for normal and osteoarthritic joints of horses. SAMPLE POPULATION: Synovial fluid from 46 normal joints in 21 horses and 16 osteoarthritic joints in 10 horses. PROCEDURE: Normal and osteoarthritic joints were identified by clinical and radiographic examination, by response to nerve blocks, during scintigraphy or surgery, or by clinicopathologic evaluation. Substance P and prostaglandin E2 contents of synovial fluid were determined by radioimmunoassay. Radio-graphs of joints were assigned a numeric score reflecting severity of lesions. Joints were assigned a numeric score reflecting anatomic location. RESULTS: Median concentrations of substance P and prostaglandin E2 were significantly increased in osteoarthritic joints, compared with normal joints. A significant correlation was found between concentrations of substance P and prostaglandin E2 in synovial fluid, but a correlation was not detected between substance P concentration in synovial fluid and anatomic location of the joint or between radiographic scores of osteoarthritic joints and concentrations of substance P or prostaglandin E2. CONCLUSIONS AND CLINICAL RELEVANCE: A correlation existed between concentrations of substance P and prostaglandin E2 in synovial fluid obtained from normal and osteoarthritic joints. However, content of substance P in synovial fluid cannot be predicted by the radiographic appearance of the joint or its anatomic location. Substance P and prostaglandin E2 may share an important and related role in the etiopathogenesis of osteoarthritis, lending credence to the importance of neurogenic inflammation in horses. 相似文献
30.
Tropical Animal Health and Production - 相似文献