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   196115篇
  免费   10467篇
  国内免费   123篇
林业   8215篇
农学   5902篇
基础科学   1302篇
  22244篇
综合类   36587篇
农作物   7454篇
水产渔业   9506篇
畜牧兽医   99865篇
园艺   2428篇
植物保护   13202篇
  2018年   2320篇
  2017年   2522篇
  2016年   2377篇
  2015年   2098篇
  2014年   2563篇
  2013年   7022篇
  2012年   4801篇
  2011年   6001篇
  2010年   3814篇
  2009年   3798篇
  2008年   5925篇
  2007年   5766篇
  2006年   5510篇
  2005年   5173篇
  2004年   5044篇
  2003年   5066篇
  2002年   4890篇
  2001年   5992篇
  2000年   5842篇
  1999年   4820篇
  1998年   1926篇
  1997年   1955篇
  1995年   2263篇
  1994年   1975篇
  1993年   1954篇
  1992年   4056篇
  1991年   4246篇
  1990年   4370篇
  1989年   4342篇
  1988年   4014篇
  1987年   4077篇
  1986年   4191篇
  1985年   4069篇
  1984年   3423篇
  1983年   3059篇
  1982年   2117篇
  1981年   1952篇
  1980年   1867篇
  1979年   3131篇
  1978年   2578篇
  1977年   2212篇
  1976年   2027篇
  1975年   2190篇
  1974年   2870篇
  1973年   2953篇
  1972年   2914篇
  1971年   2646篇
  1970年   2499篇
  1969年   2273篇
  1967年   1977篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
141.
142.
143.
144.
145.
146.
Isolated dog neutrophils exposed to known chemotactic factors assumed a bipolar configuration in suspension. This response was initiated within 2 minutes with a gradual return to spherical shape. The rate of return to sphere was positively correlated with the dose of stimulant. Dog neutrophils exposed to N-formylmethionyl-leucyl-phenylalanine (fMLP) did not adapt to bipolar conformation and did not bind radiolabeled fMLP. These findings are consistent with other species (pig and cow) that also did not respond to fMLP.  相似文献   
147.
Crystalluria results from oversaturation of urine with crystallogenic substance. However, oversaturation may occur as a result of in vitro as well as in vivo events. The microscopic appearance of crystals only represents a tentative identification of their composition because variable conditions associated with their formation, growth, and dissolution may alter their appearance. Definitive identification is dependent on physical methods such as optical crystallography, x-ray diffraction, and electron microscopic analysis.  相似文献   
148.
Disseminated Aspergillus terreus infection was diagnosed in ten previously healthy adult dogs--nine German shepherds and one dalmatian. The disease was characterized by the presence of multiple granulomas and infarcts in a wide range of organs. The kidney, spleen, and skeletal system were most commonly and severely affected. Fungal hyphae were demonstrated in large numbers within granulomas and thrombi, and A. terreus was readily isolated by culture. This disseminated mycosis appears unique; in this series of cases there was no apparent predisposing factor, portal of entry, or primary focus for dissemination of the infection.  相似文献   
149.
150.
A steam-dryer, designed and manufactured in Sweden, was evaluated for destroying Bursaphelenchus xylophilus in pine chips from southern USA. In a trial, pine chips were treated at different temperature and pressure regimes for 5 or 10min. The lowest time/temperature/pressure combination was to increase the vessel temperature from 85 to 104°C in 5 min at low pressure. Samples of pine chips were assayed for nematodes in laboratories in USA, Sweden, and Finland. No nematodes of any species were recovered from any of the treated pine-chip samples. Large and heterogeneous pieces of wood in the treated samples were also nematode-free. The apparatus was a prototype capable of handling about 400 kg h-1. The final version would have to be able to process 100-200 th-1.  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