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   315009篇
  免费   16974篇
  国内免费   674篇
林业   25017篇
农学   14382篇
基础科学   3014篇
  47985篇
综合类   36969篇
农作物   17903篇
水产渔业   18672篇
畜牧兽医   136265篇
园艺   6534篇
植物保护   25916篇
  2020年   3007篇
  2019年   3784篇
  2018年   4654篇
  2017年   5092篇
  2016年   5298篇
  2015年   4621篇
  2014年   6029篇
  2013年   16618篇
  2012年   8488篇
  2011年   10957篇
  2010年   8460篇
  2009年   8800篇
  2008年   10212篇
  2007年   9467篇
  2006年   9608篇
  2005年   8724篇
  2004年   8548篇
  2003年   8370篇
  2002年   7584篇
  2001年   8944篇
  2000年   8620篇
  1999年   7458篇
  1998年   4413篇
  1997年   4462篇
  1996年   4182篇
  1995年   4758篇
  1994年   4180篇
  1993年   3866篇
  1992年   5827篇
  1991年   6048篇
  1990年   5872篇
  1989年   5859篇
  1988年   5207篇
  1987年   5212篇
  1986年   5109篇
  1985年   5242篇
  1984年   4618篇
  1983年   4230篇
  1982年   3310篇
  1981年   3129篇
  1980年   3040篇
  1979年   3983篇
  1978年   3452篇
  1977年   3103篇
  1976年   2925篇
  1975年   2945篇
  1974年   3211篇
  1973年   3233篇
  1972年   2929篇
  1971年   2831篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
961.
A 10-month-old male domestic short-haired cat was examined because of progressive lameness, a broad face with depressed nasal bridge, small ears, corneal clouding, and multiple bone dysplasia. The cat excreted excessive amounts of glycosaminoglycan (a component of connective tissue) in its urine and had evidence of lysosomal storage of glycosaminoglycans in fibroblasts and neurons. Activity of alpha-L-iduronidase, a lysosomal enzyme involved in glycosaminoglycan degradation, was deficient in cultured fibroblasts and leukocytes. The mucopolysaccharidosis was distinct from that seen in Siamese cats in terms of the pathologic changes and the specific enzyme deficiency.  相似文献   
962.
Virus was isolated from semen and fecal samples from a bull with orchitis, testicular degeneration, aspermatogenesis, and loss of libido. Both isolates were classified as picornavirus, bovine enterovirus serotype I, on the basis of physical, chemical, and serologic characteristics. Veterinary practitioners that may suspect viral infection as a cause of bovine infertility should submit both semen and fecal samples for virus isolation and identification.  相似文献   
963.
964.
965.
966.
967.
968.
A herpesvirus and cytopathogenic bovine viral diarrhea virus were isolated from a bovine fetus aborted in the 6th month of gestation. The herpesvirus was serologically indistinguishable from bovine herpesviruses DN-599 and Movar 33/63.  相似文献   
969.
970.
Adenovirus SV-20 (ASV-20) was inoculated subcutaneously into adult rhesus macaques (Macaca mulatta), and various immunologic parameters were studied. Similar changes were observed in macaques that had anti-ASV-20 serum-neutralizing antibodies prior to inoculation and in those lacking detectable antibodies. There were absolute decreases in numbers of peripheral blood lymphocytes (PBL), erythrocyte-rosetting lymphocytes, complement-receptor lymphocytes, and Fc-receptor lymphocytes. These changes were most significant (P less than 0.05) on postinoculation days (PID) 3 and 7. Mitogenic responsiveness to concanavalin A, phytohemagglutinin, and pokeweed mitogen in cultured PBL from immune and nonimmune macaques was depressed on PID 3, 7, and 14. Ultraviolet-inactivated ASV-20 caused moderate suppression of phytohemagglutinin-induced mitogenesis when viral particles and lectin were added simultaneously to PBL cultures. Plasma cortisol (hydrocortisone) values were not significantly altered following inoculation of ASV-20. High titers of anti-ASV-20 antibody developed by PID 7 in nonimmune macaques, and previously immune macaques showed a booster effect in the same time period. Antibody titers were still increased 120 days after inoculation. There was no clinical evidence of an adverse effect of ASV-20 infection in these macaques.  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