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   7656篇
  免费   47篇
  国内免费   14篇
林业   734篇
农学   234篇
基础科学   50篇
  967篇
综合类   341篇
农作物   516篇
水产渔业   465篇
畜牧兽医   3694篇
园艺   202篇
植物保护   514篇
  2022年   15篇
  2019年   13篇
  2018年   120篇
  2017年   186篇
  2016年   173篇
  2015年   235篇
  2014年   205篇
  2013年   161篇
  2012年   455篇
  2011年   325篇
  2010年   118篇
  2009年   83篇
  2008年   76篇
  2007年   53篇
  2006年   55篇
  2005年   790篇
  2004年   668篇
  2003年   459篇
  2002年   119篇
  2001年   134篇
  2000年   34篇
  1999年   151篇
  1992年   117篇
  1991年   145篇
  1990年   168篇
  1989年   147篇
  1988年   171篇
  1987年   113篇
  1986年   143篇
  1985年   117篇
  1984年   91篇
  1983年   81篇
  1982年   33篇
  1981年   17篇
  1980年   24篇
  1979年   133篇
  1978年   96篇
  1977年   91篇
  1976年   77篇
  1975年   137篇
  1974年   129篇
  1973年   116篇
  1972年   138篇
  1971年   118篇
  1970年   88篇
  1969年   102篇
  1968年   113篇
  1967年   125篇
  1966年   102篇
  1965年   70篇
排序方式: 共有7717条查询结果,搜索用时 15 毫秒
991.
992.
In two lambs and two calves infected experimentally with infective larvae of Elaphostrongylus rangiferi, lymphohistiocytic and eosinophilic cell infiltrations in the leptomeninges and lymphohistiocytic granulomas in the perineurium of the cauda equina of the CNS were demonstrated. These histopathological changes are similar to the lesions usually demonstrated in reindeer with elaphostrongylosis. No parasites were found, however, in the CNS or other organs.  相似文献   
993.
994.
995.
996.
In 2 experiments with a total of 28 breeding sows of the country species studies were made of the fermentation, production and absorption of volatile fatty acids (VFA) in the large intestine after feeding variously treated straw materials in concentrate--straw meal mixtures. Experiment 1 ascertained that supplements of untreated (I), HCl treated (II) and partly hydrolysed straw meal (III, treatment with subsequent steaming) caused a decrease of the VFA concentration as well as considerable molar changes of the VFA in the caecal and colonal digesta in comparison of the sole feeding with concentrate (IV). The straw fibre integration increased the molar acetate quota at the expense decreased propionate and butyrate fermentation. Considering the straw meal variants this effects was least distinct after the feeding of partly hydrolysed straw meal (III). In experiment 2, which comprised the simultaneous ascertainment of VFA production in the feeding variants I and III and which was based on a representative number of animals per test group (n = 10), there were significant differences between the production quotas (I = 992; III = 1,300 mmol/animal.d) and in the absorption quotas of VFA (I = 63; II = 78%). The digestible energy from the VFA in the large intestine amounted to 711 kJ/d (I) and 1,183 kJ/d (III). The derived higher net energy gain from the hydrolysed straw product (III) was calculated at 590 kJ (40EFUpig/kg DM) and discussed together with results of feed value increase from the digestibility experiments.  相似文献   
997.
998.
Cell surface hydrophobicities of streptococci of serological group B were determined by the adherence of the bacteria to hexadecane droplets. A significant adherence to hexadecane was observed with the group B streptococcal type reference strains Ib, V, Ic, R and X, but not with those of serotype Ia, II, III and IV. Cultivation of the bacteria in microcapsule-inducing media reduced the hexadecane adherence properties. The adherence to hexadecane was not related to fibrinogen binding properties of the cultures. Screening a large number of group B streptococci isolated from humans and bovines revealed that those with polysaccharide type antigen alone were generally hydrophilic, those with protein antigen alone or with protein antigen in combination with polysaccharide antigen were mostly hydrophobic. Cultivation of the bacteria under microaerobic conditions or after a single mouse passage enhanced microcapsule production and correspondingly reduced the hexadecane adherence values. Treatment of the bacteria by guanidinium chloride or by neuraminidase enhanced the hexadecane adherence. The hydrophobic component on group B streptococcal surface appeared to be partly inactivated by heat or proteolytic treatment of the bacteria.  相似文献   
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