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   30093篇
  免费   1286篇
  国内免费   6篇
林业   1067篇
农学   891篇
基础科学   174篇
  4487篇
综合类   3943篇
农作物   1122篇
水产渔业   1142篇
畜牧兽医   16462篇
园艺   334篇
植物保护   1763篇
  2020年   265篇
  2019年   331篇
  2018年   600篇
  2017年   663篇
  2016年   566篇
  2015年   364篇
  2014年   552篇
  2013年   1662篇
  2012年   863篇
  2011年   1115篇
  2010年   809篇
  2009年   761篇
  2008年   1077篇
  2007年   1053篇
  2006年   890篇
  2005年   713篇
  2004年   718篇
  2003年   654篇
  2002年   575篇
  2001年   740篇
  2000年   726篇
  1999年   531篇
  1998年   233篇
  1997年   213篇
  1995年   267篇
  1994年   218篇
  1992年   400篇
  1991年   415篇
  1990年   431篇
  1989年   440篇
  1988年   344篇
  1987年   353篇
  1986年   383篇
  1985年   342篇
  1984年   331篇
  1983年   303篇
  1979年   481篇
  1978年   328篇
  1977年   370篇
  1976年   468篇
  1975年   485篇
  1974年   523篇
  1973年   480篇
  1972年   438篇
  1971年   354篇
  1970年   372篇
  1969年   434篇
  1968年   441篇
  1967年   446篇
  1966年   438篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
Adverse events can occur after rabies post‐exposure prophylaxis (PEP), and linkage to causality is often difficult to determine. We report a case of recurrent temporary paralysis that began immediately after the initiation of rabies PEP in a man exposed to a bat. The recurrent temporary paralysis first occurred in the patient after his initial dose and then again after day 3 of his rabies PEP. The PEP was terminated prior to a serologic response. The patient continued to experience numerous discrete episodes of temporary paralysis for over two years.  相似文献   
92.
Soluble proteins from the latex of Calotropis procera (LP) were investigated in vitro and in vivo for digestibility as the latex has previously been shown to produce considerable toxic effects on animals. The latex is also an important biologically active compound that displays antiinflammatory and antidiarrhea properties. The proteins were digested by the action of trypsin, pepsin or chemotrypsin as revealed by gel filtration and SDS-PAGE analysis. Furthermore, the full LP digestion was easily achieved by protease treatment. Rabbit polyclonal antibodies raised against LP failed to detect cross-reactive molecules in fecal material of experimental rats following 35 consecutive days of LP consumption in water. Similar patterns of electrophoresis were observed for the negligible amounts of protein observed in the fecal extracts of control and test animals. No death or toxic effects were observed among animals. Taken together these results suggest that harmful and toxic effects on animals of the latex from C. procera are present in its rubber and low molecular weight fractions rather than its protein content.  相似文献   
93.
The antifungal activity of Eugenia cariophyllata essential oil and eugenol, its major constituent, on fungal strains isolated from onychomycosis was evaluated. The natural products presented prominent antifungal action with MIC of 1% and 4%, respectively.  相似文献   
94.
95.
Summary The observed kinetics of Pinus pinaster bark with acetic acid after alkali treatment, with or without intervening acid prehydrolysis, are satisfactorily explained by a model involving both solubilization and condensation reactions.This study was subsidised by the Xunta de Galicia. J. González is grateful to DGICYT for a research grant  相似文献   
96.
Management of subterranean clover (Trifolium subterraneum L.) understory grown with loblolly pine (Pinus taeda L.) and slash pine (Pinus elliottii Engelm.) resulted in differences in both clover yield and pine diameter. Loblolly and slash pines were planted into a subterranean clover pasture in 1984. Suppression of warm season herbaceous vegetation by applying herbicides or disking the site in late summer resulted in significantly greater subterranean clover production than on the control site where no additional understory management was applied. Pine species had no effects on clover yield. The N content of the pine foliage on the blocks managed with herbicide application or disking generally was significantly greater than the control from the 5th through 7th growing seasons (1988–1990). The dbh of the pine trees in the disked and herbicide treatments was greater than the control after the 7th growing season (1990).  相似文献   
97.
Defence reactions to the fungus Phaeolus schweinitzii were studied in spruce, pine, larch and Douglas-fir callus cultures. It was found that the defence reaction of the callus culture could indicate the degree of the resistance of the tree species to the wood-destroying fungus.  相似文献   
98.
99.
Summary Lignin topochemistry of tracheid walls from a deformed, copper deficient Pinus radiata (D. Don) tree was examined by linescan and point analyses using a Scanning Electron Microscope and Energy Dispersive Spectrometry. Both opposite and compression wood had abnormal lignin distributions compared to those observed in normal wood from a straight tree. Lignin contents in the compound middle lamella were lower than lignin contents in the secondary wall in both opposite and compression wood tracheids.One of us (G. D.) held a Commonwealth Forestry Postgraduate Research Award during this study. The research was supported in part by a grant from the Reserve Bank of Australia Rural Credits Development Fund, the Pine Fund, and members of the forest industry  相似文献   
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