首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   1417篇
  免费   49篇
林业   110篇
农学   66篇
  296篇
综合类   57篇
农作物   58篇
水产渔业   191篇
畜牧兽医   575篇
园艺   9篇
植物保护   104篇
  2023年   8篇
  2022年   25篇
  2021年   22篇
  2020年   20篇
  2019年   21篇
  2018年   27篇
  2017年   38篇
  2016年   38篇
  2015年   46篇
  2014年   46篇
  2013年   140篇
  2012年   71篇
  2011年   91篇
  2010年   40篇
  2009年   35篇
  2008年   82篇
  2007年   98篇
  2006年   82篇
  2005年   88篇
  2004年   53篇
  2003年   47篇
  2002年   55篇
  2001年   52篇
  2000年   33篇
  1999年   31篇
  1998年   20篇
  1997年   5篇
  1996年   12篇
  1995年   6篇
  1994年   6篇
  1993年   6篇
  1992年   14篇
  1991年   12篇
  1990年   9篇
  1989年   14篇
  1988年   10篇
  1987年   5篇
  1986年   6篇
  1985年   4篇
  1984年   3篇
  1983年   4篇
  1979年   3篇
  1978年   3篇
  1977年   4篇
  1975年   5篇
  1972年   2篇
  1971年   2篇
  1969年   4篇
  1968年   3篇
  1967年   3篇
排序方式: 共有1466条查询结果,搜索用时 31 毫秒
981.
Based on histological structure and cellular formation, the endocrine pancreas (pars endocrina pancreatis) (PEP) or pancreatic islet (insulae pancreaticae), was divided into two types in the dog. One type of PEP was the islet of Langerhans. In the glandular lobule, the islet was surrounded by exocrine acini. The other type of PEP, in general, exhibited a feature of a neuro-insular complex. It was found within the interlobular connective tissue of the pancreas. This type of PEP was attached to a nerve bundle or ganglion. In the pancreas of the immature dog, a large population of endocrine cells was recognized to form a blood islet within the neuro-insular complex.  相似文献   
982.
At many hatcheries in Japan, a high incidence of lordosis is being reported among marine physoclistous juveniles of red sea bream, Japanese sea bass, and amberjack. Extensive studies being conducted since 1975 to tackle this problem have led to the following conclusions, and effective countermeasures are being proposed.
During early larval development in the temporary physostomous stage, fish must be able to gulp air at the water surface for normal development of the swim bladder. The juveniles that fail to gulp air swim upward in an oblique position because of insufficient buoyancy, causing the backbone to curve in a V-shape.
The managerial solutions proposed are: 1) reduce the strong water current caused by vigorous aeration; 2) provide nutrient-enriched rotifers to produce healthy swimming larvae; and 3) prevent any oily film formation on the water surface.  相似文献   
983.
984.
985.
986.
987.
988.
There is significant lack of basic hematologic and immunological data in adult sows. Therefore, aim of this study was to provide respective reference intervals. 32 clinically healthy multiparous Large White sows aged 33.5 ± 9.6 months and all of them two months postpartum were included in this study. Mean erythrocyte count was 5.5 ± 0.7 × 10(6)/μl and total leukocyte count was 12.1 ± 2.1 × 10(3)/μl. Proportion of lymphocytes was 44.7 ± 10.2% and of neutrophils 41.6 ± 11.0%. The ratio of na?ve T helper (Th) cells to memory Th cells was 1:3.1 and the ratio of Th cells to cytotoxic T cells (CTLs) was 1:4.2. Proportions of regulatory T cells, NK cells, and CD21(+) B cells were lower (3.1, 2.6, and 6.0%) than those of memory Th cells ranging from 8.8 to 27.5% depending on the activation status and CTLs with 37.3%. γδ T cells were found at comparably high numbers (19.1%). Flow cytometric measurement of intracellular cytokines in PBMCs revealed marginal levels for IL-1β, IL-2, IL-4, IL-6, IL-10, and IL-12p35, but remarkable levels for TNF-α and IFN-γ. Highest mRNA levels were found for IL-1, IL-10, and TNF-α, with TNF-α showing the least inter-individual variation.  相似文献   
989.
The tick Rhipicephalus (Boophilus) microplus is one of the most important bovine ectoparasites, a disease vector responsible for losses in meat and milk productions. A cysteine protease similar to cathepsin L, named BmCL1, was previously identified in R. microplus gut, suggesting a role of the enzyme in meal digestion. In this work, BmCL1 was successfully expressed in Pichia pastoris system, yielding 54.8 mg/L of culture and its activity was analyzed by synthetic substrates and against a R. microplus cysteine protease inhibitor, Bmcystatin. After rBmCl1 biochemical characterization it was used in a selection of a peptide phage library to determine rBmCL1 substrate preference. Obtained sequenced clones showed that rBmCL1 has preference for Leu or Arg at P(1) position. The preference for Leu at position P(1) and the activation of BmCL1 after a Leu amino acid residue suggest possible self activation.  相似文献   
990.
We examined for 'Candidatus Mycoplasma haemominutum' infection in 167 blood samples collected from domestic dogs between 2008 and 2009 in the Tohoku area, Japan, and found 5 (3.0%) were positive by PCR assay. This is the first demonstration of 'Candidatus Mycoplasma haemominutum', a feline haemotropic mycoplasma, in the dogs raised in Japan.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号