全文获取类型
收费全文 | 1529篇 |
免费 | 76篇 |
国内免费 | 2篇 |
专业分类
林业 | 143篇 |
农学 | 227篇 |
基础科学 | 25篇 |
307篇 | |
综合类 | 48篇 |
农作物 | 92篇 |
水产渔业 | 48篇 |
畜牧兽医 | 517篇 |
园艺 | 66篇 |
植物保护 | 134篇 |
出版年
2023年 | 11篇 |
2022年 | 22篇 |
2021年 | 33篇 |
2020年 | 31篇 |
2019年 | 25篇 |
2018年 | 70篇 |
2017年 | 57篇 |
2016年 | 69篇 |
2015年 | 38篇 |
2014年 | 40篇 |
2013年 | 125篇 |
2012年 | 61篇 |
2011年 | 79篇 |
2010年 | 59篇 |
2009年 | 47篇 |
2008年 | 69篇 |
2007年 | 57篇 |
2006年 | 46篇 |
2005年 | 42篇 |
2004年 | 34篇 |
2003年 | 39篇 |
2002年 | 41篇 |
2001年 | 28篇 |
2000年 | 26篇 |
1999年 | 29篇 |
1998年 | 13篇 |
1997年 | 9篇 |
1996年 | 15篇 |
1995年 | 11篇 |
1994年 | 10篇 |
1993年 | 11篇 |
1992年 | 18篇 |
1991年 | 20篇 |
1990年 | 30篇 |
1989年 | 21篇 |
1988年 | 14篇 |
1987年 | 20篇 |
1986年 | 17篇 |
1985年 | 17篇 |
1984年 | 11篇 |
1983年 | 12篇 |
1982年 | 14篇 |
1981年 | 17篇 |
1980年 | 14篇 |
1979年 | 21篇 |
1978年 | 15篇 |
1977年 | 11篇 |
1970年 | 8篇 |
1969年 | 14篇 |
1968年 | 12篇 |
排序方式: 共有1607条查询结果,搜索用时 250 毫秒
21.
Evaluation of Cytotoxic Responses Caused by Selected Organophosphorus Esters in Chick Sympathetic Ganglia Cultures
下载免费PDF全文
![点击此处可从《Canadian journal of veterinary research》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Ten day old chick sympathetic ganglia cultured in a microslide assembly were treated with a selected group of organophosphate pesticides to evaluate their cytotoxicity ranges, and the usefulness of such a model for screening pesticides. Examination by phase contrast and light microscopy for chemically-induced morphological alteration of nerve fibers, glial cells and neurons provided the criteria for quantitation and assessment of the toxic effects. Concentrations that produced half-maximal effects ranged from 1 × 10-6M (severely toxic) for methylparathian, diazinon, paraoxon, mevinphos, diisopropylfluorophosphate, tri-o-tolyl phosphate and its mixed isomers to a 1 × 10-3M (intermediate) for malathion, leptophos, coumaphos, mono- and dicrotophos. Some or no effects were evident at 1 × 102-M for O'ethyl-O-p-nitrophenyl phenyl phosphonothioate, tri-m-tolylphosphate, chlorpyriphos and triphenyl phosphate. In all instances, nerve fibers were more sensitive than neurons or glial cells to insecticides. All cellular growth was inhibited at 1 × 10-2M (except triphenyl phosphate). Below 1 x 10-7M, no inhibitory effects were evident. The secondary abnormalities included decreased cellular migration, diffuse cellular growth pattern, increased vacuolization, nerve fiber swelling and cellular degeneration. The cytotoxic effects of these chemicals do not appear to be related to in vivo toxicity or cholinesterase inhibition potential. 相似文献
22.
23.
24.
25.
R. C. Joshi B. Sharma S. K. Bandyopadhyay R. P. Bansal 《Tropical animal health and production》1984,16(3):167-170
Rinderpest antibodies were detected by employing the fluorescent antibody test (FAT) and the immunoperoxidase test (IPT) and the results were compared with the counterimmuno electrophoresis test (CIE). FAT was found to be the most sensitive in detecting post-vaccinal antibodies followed by IPT and CIE tests. 相似文献
26.
Sandeep K. Sharma MVSc Ambika P. Singh MVSc PhD Rishi Tayal MVSc Inder S. Chandna MVSc PhD 《Veterinary radiology & ultrasound》1984,25(1):17-22
Contrast radiography of the alimentary canal was conducted in six adult sheep with barium sulfate (70% W/V, 25–30 ml/kg). A period of 12 hours was adequate for opacification of most parts of the gastrointestinal tract. The presence of contrast medium in different parts of the alimentary canal was noted for as long as 60 hours. The right lateral view was adequate for visualization of most structures, but the typical laminar mucosal pattern of the omasum and the spiral mucosal folds of the abomasum were demonstrated better on the ventrodorsal view. 相似文献
27.
28.
Rautenschlein S Sheikh AM Patnayak DP Miller RL Sharma JM Goyal SM 《Avian diseases》2002,46(3):555-561
Since 1997, avian pneumovirus (APV) has caused estimated annual losses of $15 million to the Minnesota turkey industry. In order to develop an attenuated live vaccine against APV, we serially passaged a Minnesota isolate of APV (APV/MN/turkey/1-a/97) in vitro in cell cultures for 41 passages. Laboratory experiments with this high-passage virus (P41) indicated that the attenuated virus provided immunogenic protection to turkeys against challenge with virulent APV, although some birds showed mild to moderate dinical signs after inoculation. To reduce the residual pathogenicity of P41, while maintaining its immunogenicity, we decided to vaccinate turkeys with P41 in the presence of an immunomodulator, S-28828 (1-n-butyl-2-ethoxymethyl-1H-imidazo[4,5-c]quinolin-4-amine-hydrochloride), which is a potent cytokine inducer. The combined inoculation of S-28828 (5 mg/kg body weight) and P41 resulted in a significant reduction in the incidence of virus-induced clinical signs in comparison with birds that received P41 without immunomodulator (P < 0.05). Only 17% of birds inoculated with S-28828 + APV P41 showed mild respiratory symptoms at 5 days postinoculation as compared with 46% of the vaccinated turkeys that did not receive S-28828. Vaccination with either P41 or with P41 + S-28828 protected turkeys against dinical signs and viral replication after challenge with virulent APV. These results indicate that immunomodulators, such as S-28828, may act as good vaccine adjuvants that can reduce the pathogenicity but maintain the immunogenicity of partially attenuated vaccines. 相似文献
29.
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
30.
Polymerase chain reaction (PCR) was used to amplify the spacer regions between the 16S and 23S genes of rRNA genetic loci of Salmonella serovars for their rapid identification. These genetic loci revealed a significant level of polymorphism in length across the species/serovar lines. When the 16S-23S spacer region amplification products were subjected to agarose electrophoresis, the patterns observed could be used to distinguish all the serovars of Salmonella tested. Unique elements obtained in amplification products were mostly clustered at serovar level, although certain genus-specific patterns were also observed. On the basis of the results obtained, the amplification of 16S-23S ribosomal spacer region could suitably be used in a PCR-based identification method for Salmonella serovars. 相似文献