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   210篇
  免费   12篇
  国内免费   1篇
林业   4篇
基础科学   1篇
  8篇
综合类   28篇
农作物   5篇
水产渔业   8篇
畜牧兽医   160篇
园艺   4篇
植物保护   5篇
  2023年   1篇
  2021年   3篇
  2020年   6篇
  2019年   3篇
  2017年   9篇
  2016年   2篇
  2015年   4篇
  2014年   4篇
  2013年   14篇
  2012年   15篇
  2011年   11篇
  2010年   10篇
  2009年   3篇
  2008年   9篇
  2007年   10篇
  2006年   9篇
  2005年   5篇
  2004年   6篇
  2003年   7篇
  2002年   2篇
  2001年   5篇
  2000年   7篇
  1999年   8篇
  1998年   17篇
  1997年   2篇
  1996年   9篇
  1995年   2篇
  1994年   1篇
  1993年   5篇
  1992年   3篇
  1991年   6篇
  1990年   5篇
  1989年   7篇
  1988年   1篇
  1986年   2篇
  1985年   2篇
  1984年   1篇
  1980年   1篇
  1977年   1篇
  1969年   2篇
  1953年   1篇
  1950年   1篇
  1938年   1篇
排序方式: 共有223条查询结果,搜索用时 15 毫秒
21.
Abstract Wild-caught mutton snapper Lutjanus analis , a high-value marine food fish species, matured in flow-through seawater (36 g/L) tanks after 3 yr in captivity. On 31 May 1995, a female with a mean oocyte diameter of 382 μm was injected with human chorionic gonadotropin (HCG) (500 IU/kg body wt.) followed 24 h later by a second injection (1,000 IU/kg body wt.). At the time of the second injection, three males were injected with HCG (500 IU/ kg body wt.). Voluntary spawning occurred 33 h after the first injection, with a total of 534, 781 eggs released. Fertilization rate was 75.7%, while average diameter of fertilized eggs was 783 μm. Embryos were stocked in a 30-m3 outdoor tank at a density of 10.5/L. On day 2 post-hatching (d2ph), larval density was 8.61 larvae/L, and average notochord length was 2.6 mm. Larvae were fed ss-type rotifers from dl-d28ph, Artemia nauplii from 0–08ph, and artificial diets (52–48% protein) from d24-d38ph. On d38ph, fish averaged 0.308 g and 22.2 mm standard length. Survival (from d2ph) was 14.3%, with a total of 36,900 post-metamorphic juveniles produced. On d97ph, 1,390 hatchery-reared juveniles (avg. wt. = 10.5 g) were stocked into two 14.5-m3 recirculating seawater tanks (695 fish/tank; 48 fish/m3) and fed a 56% protein pellet. After 168 d, fish averaged 140.8 g, with a survival rate of 97.8% and a feed conversion ratio (dry wt./wet wt.) of 1.2. These preliminary results reveal the mutton snapper to be a prime, new candidate species for commercial cultivation.  相似文献   
22.
23.
24.
Subsets of murine CD4+ T cells localize to different areas of the spleen after adoptive transfer. Na?ve and T helper 1 (TH1) cells, which express the chemokine receptor CCR7, are home to the periarteriolar lymphoid sheath, whereas activated TH2 cells, which lack CCR7, form rings at the periphery of the T cell zones near B cell follicles. Retroviral transduction of TH2 cells with CCR7 forces them to localize in a TH1-like pattern and inhibits their participation in B cell help in vivo but not in vitro. Thus, differential expression of chemokine receptors results in unique cellular migration patterns that are important for effective immune responses.  相似文献   
25.
The preparation and analysis of inorganic-organic polymer nanocomposites consisting of inorganic nanowires and multiwire "cables" in a random-coil organic polymer host is reported. Dissolution of inorganic (LiMo3Se3)n wires in a strongly coordinating monomer, vinylene carbonate, and the use of a rapid polymerization in the presence of a cross-linking agent produce nanocomposites without phase separation. Polymerization of dilute solutions yields a material containing mostly (Mo3Se3(-))n mono- and biwires, 6 to 20 angstroms in diameter and 50 to 100 nanometers long. Polymerization of more concentrated liquid crystalline solutions yields a nanocomposite containing oriented multiwire cables, 20 to 40 angstroms in diameter and up to 1500 nanometers long, that display optical anisotropy and electrical conductivity.  相似文献   
26.
27.
Hypersomatotropism and insulin-resistant diabetes mellitus in a cat   总被引:1,自引:0,他引:1  
In this report, we described the clinical, radiographic, and echocardiographic findings in a cat with hypersomatotropism and insulin-resistant diabetes mellitus. Growth hormone determinations were made because of persistent hyperglycemia despite insulin requirements exceeding 2.2 U/kg of body weight, and the acromegalic features of the cat. Also, the results of a therapeutic trial in which a long-acting analogue of somatostatin was used are discussed.  相似文献   
28.
A 6-month-old stunted female Doberman Pinscher was found to have a 77,X0 chromosomal complement. The ovaries were small, consisting primarily of interstitial-type cells and solid epithelial cords. The dam, sire, and a male littermate had normal karyotypes.  相似文献   
29.
30.
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