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   8154篇
  免费   60篇
  国内免费   16篇
林业   777篇
农学   243篇
基础科学   52篇
  1055篇
综合类   364篇
农作物   518篇
水产渔业   550篇
畜牧兽医   3937篇
园艺   204篇
植物保护   530篇
  2022年   20篇
  2020年   17篇
  2018年   129篇
  2017年   192篇
  2016年   177篇
  2015年   240篇
  2014年   216篇
  2013年   232篇
  2012年   480篇
  2011年   347篇
  2010年   132篇
  2009年   107篇
  2008年   95篇
  2007年   86篇
  2006年   78篇
  2005年   815篇
  2004年   692篇
  2003年   485篇
  2002年   145篇
  2001年   149篇
  2000年   66篇
  1999年   163篇
  1992年   122篇
  1991年   151篇
  1990年   170篇
  1989年   154篇
  1988年   175篇
  1987年   121篇
  1986年   145篇
  1985年   120篇
  1984年   92篇
  1983年   84篇
  1982年   33篇
  1981年   18篇
  1980年   24篇
  1979年   134篇
  1978年   98篇
  1977年   91篇
  1976年   77篇
  1975年   137篇
  1974年   130篇
  1973年   116篇
  1972年   139篇
  1971年   119篇
  1970年   88篇
  1969年   102篇
  1968年   114篇
  1967年   126篇
  1966年   102篇
  1965年   71篇
排序方式: 共有8230条查询结果,搜索用时 15 毫秒
991.
A literature review of surgical techniques used for resection of periocular tumors with conservation of the eyelid is accompanied by a report of the author's personal experience with blepharoplasty in cattle. Included are 13 cases of Fleckvieh cows with squamous cell carcinoma. Five animals were without tumor recurrence after an average time of 10.7 months, while seven animals with recurrence of the neoplasm had mean survival time of 10.6 months. Those five cows had been slaughtered for unrelated problems, the others because of recurrence of the ocular tumor. One patient was slaughtered five days after surgery because of complications of wound healing.  相似文献   
992.
This paper reviews available literature on the efficacy of acaricides against Amblyomma hebraeum and other tick species, and presents information on tests done with registered chemicals in the laboratory. Little published information is available on the efficacy of chemicals specifically against A. hebraeum. A host of formulations are registered for use as acaricides on cattle, sheep, and goats in South Africa and thus, by implication, against this species. Resistance has only been described to arsenic and toxaphene in Southern Africa; the other registered products are generally considered to be effective. In contrast, many efficacy tests of various chemicals in different formulations against other Amblyomma spp. have been described. These publications have mainly emanated from the USA, where bite-wounds of these ticks serve as oviposition sites for screwworm flies. In this paper, Amblyomma maculatum and Amblyomma variegatum are included as potential heartwater vectors. The acaricidal efficacy of a number of compounds, representative of different chemical classes, was tested in South Africa against an arsenic and organochlorine resistant strain of A. hebraeum. The engorged adult female immersion method was used. A disconcerting discovery was that several of these registered products failed to control this tick when used at their recommended concentrations. It is concluded that many chemicals which fail against A. hebraeum on cattle do so because of insufficient persistence. Exposure of this tick to lower levels of existing chemicals, but for longer periods, ought to provide satisfactory control for many years.  相似文献   
993.
994.
995.
Interactions between the predacious hyphomycete Arthrobotrys oligospora and third-stage larvae of nine animal-parasitic nematodes were tested in vitro. The trap-inducing capabilities of the ruminant trichostrongylus Cooperia oncophora, C. curticei, Haemonchus contortus and Ostertagia ostertagi and of equine cyathostomes were almost comparable to those of free-living soil nematodes, and significantly higher than those of the porcine Oesophagostomum dentatum and Oe. quadrispinulatum and of the murine Nematospiroides dubius. The trap-forming potential of Dictyocaulus viviparus was poor. All animal-parasitic nematodes were rapidly captured when fungal traps had been pre-induced in high numbers. The possible influence of predacious fungi on animal-parasitic nematode populations under natural conditions in the field is discussed.  相似文献   
996.
997.
998.
999.
1000.
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