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   204321篇
  免费   10902篇
  国内免费   139篇
林业   8688篇
农学   6336篇
基础科学   1370篇
  25149篇
综合类   36731篇
农作物   8194篇
水产渔业   9771篇
畜牧兽医   103369篇
园艺   2697篇
植物保护   13057篇
  2019年   1866篇
  2018年   2730篇
  2017年   3102篇
  2016年   2859篇
  2015年   2394篇
  2014年   3019篇
  2013年   8028篇
  2012年   5666篇
  2011年   7035篇
  2010年   4648篇
  2009年   4698篇
  2008年   7004篇
  2007年   6530篇
  2006年   6114篇
  2005年   5771篇
  2004年   5648篇
  2003年   5720篇
  2002年   5296篇
  2001年   6144篇
  2000年   6215篇
  1999年   4840篇
  1998年   2160篇
  1997年   2106篇
  1996年   1959篇
  1995年   2366篇
  1994年   2157篇
  1993年   2018篇
  1992年   4121篇
  1991年   4394篇
  1990年   4264篇
  1989年   4256篇
  1988年   3927篇
  1987年   3925篇
  1986年   4097篇
  1985年   3984篇
  1984年   3230篇
  1983年   2940篇
  1982年   1951篇
  1979年   3049篇
  1978年   2462篇
  1977年   2007篇
  1976年   2040篇
  1975年   2150篇
  1974年   2619篇
  1973年   2735篇
  1972年   2607篇
  1971年   2476篇
  1970年   2320篇
  1969年   2281篇
  1967年   1958篇
排序方式: 共有10000条查询结果,搜索用时 140 毫秒
91.
Thirteen mixed-breed beef bulls, 1 to 4 years old, were used to determine the effect of live and dead filarial nematodes, Setaria labiatopapillosa, placed in the vaginal cavity of the testes. When dead worms were used, granulomatous lesions developed on the tunica vaginalis parietalis in 7 of 8 testes. The lesions were similar to those seen in some clinical cases of periorchitis. Similar lesions developed in 5 of 6 testes after live worms were implanted in the vaginal cavity of the testes and tetramisole (8 mg/kg) was injected subcutaneously 6 days after implantation. When live worms were implanted and tetramisole was not given, lesions developed in 3 of 6 testes. It was concluded that the granulomatous reaction was a local response to dead or killed S labiatopapillosa.  相似文献   
92.
Mid-storage hydration-dehydration treatments with medium-vigour lettuce seed very effectively reduced physiological deterioration in storage and ultimately showed better field emergence and final yield. Soaking-drying treatment of high-vigour lettuce seed was not effective. Pre-sowing treatment of medium-vigour lettuce seed, though less effective than mid-storage treatment, gave better field performance, but high-vigour seed did not benefit from the treatment. For carrot, both mid-storage and pre-sowing seed treatments proved beneficial, with the former showing better performance than the latter. Unlike lettuce, well-preserved carrot seed responded positively to the pre-sowing treatment.  相似文献   
93.
Washed and unwashed red blood cells (RBC) from young calves, adult cattle, hamsters and humans were incubated with Leptospira interrogans serovars pomona and ballum. Washed cells suspended in saline were always haemolysed while unwashed cells and those which were washed and resuspended in plasma were never haemolysed, despite the presence of large numbers of organisms within the culture supernatant. Pomona produced greater haemolysis of cattle and human RBC than did ballum, but with hamster RBC ballum produced greater haemolysis than did pomona. A group of 6- to 9-month-old cattle infected with pomona showed no signs of clinical disease and RBC taken from them before infection and during the development of antibodies to pomona were haemolysed by pomona only after the cells were washed. Plasma therefore appears to have a protective function. This in vitro protective function of plasma even extended to plasma from young seronegative calves.  相似文献   
94.
95.
96.
In addition to the well-defined phenolic estrogens in human pregnancy urine there appears to be another estrogenic substance which is a neutral non-ketonic compound.  相似文献   
97.
98.
W A 《Science (New York, N.Y.)》1886,7(170):416-417
  相似文献   
99.
100.
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