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   116087篇
  免费   5714篇
  国内免费   76篇
林业   5325篇
农学   3411篇
基础科学   805篇
  13038篇
综合类   21395篇
农作物   4927篇
水产渔业   5172篇
畜牧兽医   59526篇
园艺   1412篇
植物保护   6866篇
  2018年   1360篇
  2017年   1575篇
  2016年   1505篇
  2015年   1354篇
  2014年   1521篇
  2013年   4237篇
  2012年   3082篇
  2011年   3599篇
  2010年   2260篇
  2009年   2220篇
  2008年   3432篇
  2007年   3135篇
  2006年   2977篇
  2005年   3523篇
  2004年   3511篇
  2003年   3241篇
  2002年   2849篇
  2001年   3510篇
  2000年   3463篇
  1999年   2679篇
  1998年   1115篇
  1997年   1138篇
  1995年   1294篇
  1994年   1205篇
  1993年   1174篇
  1992年   2538篇
  1991年   2728篇
  1990年   2663篇
  1989年   2712篇
  1988年   2465篇
  1987年   2511篇
  1986年   2650篇
  1985年   2550篇
  1984年   2061篇
  1983年   1883篇
  1982年   1214篇
  1981年   1163篇
  1979年   1925篇
  1978年   1535篇
  1977年   1275篇
  1976年   1228篇
  1975年   1328篇
  1974年   1697篇
  1973年   1754篇
  1972年   1761篇
  1971年   1662篇
  1970年   1531篇
  1969年   1392篇
  1968年   1145篇
  1967年   1226篇
排序方式: 共有10000条查询结果,搜索用时 132 毫秒
61.
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   
62.
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   
63.
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   
64.
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   
65.
66.
67.
68.
69.
70.
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