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   36163篇
  免费   2738篇
  国内免费   8篇
  38909篇
  2023年   296篇
  2022年   443篇
  2021年   864篇
  2020年   643篇
  2019年   831篇
  2018年   1067篇
  2017年   1019篇
  2016年   1415篇
  2015年   1732篇
  2014年   1865篇
  2013年   2585篇
  2012年   2843篇
  2011年   2711篇
  2010年   1780篇
  2009年   1504篇
  2008年   1831篇
  2007年   1771篇
  2006年   1710篇
  2005年   1432篇
  2004年   1408篇
  2003年   1322篇
  2002年   1187篇
  2001年   704篇
  2000年   680篇
  1999年   592篇
  1998年   367篇
  1997年   267篇
  1996年   265篇
  1995年   244篇
  1994年   183篇
  1993年   178篇
  1992年   282篇
  1991年   264篇
  1990年   234篇
  1989年   218篇
  1988年   188篇
  1987年   193篇
  1986年   173篇
  1985年   146篇
  1984年   158篇
  1983年   111篇
  1982年   106篇
  1981年   86篇
  1980年   79篇
  1979年   104篇
  1978年   67篇
  1977年   60篇
  1975年   62篇
  1974年   85篇
  1971年   58篇
排序方式: 共有10000条查询结果,搜索用时 7 毫秒
61.
A simple and reliable method for G-banding chromosomes from human and mammalian cells is described. This rapid method combines hot saline and trypsin treatments and yields high quality G-bands in both bone marrow and cultured cells.  相似文献   
62.
Enzyme activities and protein content were determined in the cytosolic and mitochondrial fractions of liver homogenates obtained from Rh(III) complex-, thioacetamide- and thioacetamide + Rh(III) complex-treated rats. The Rh(III) complex administered to nonthioacetamide-treated rats produced no significant changes either in the enzymatic activities assayed or in the protein concentration. The Rh(III) complex administered to thioacetamide-treated rats produced significant restoration of the following altered values: cytosolic and mitochondrial aspartate aminotransferase, glutamate dehydrogenase, NADP-isocitrate dehydrogenase, and protein concentration. However, a further increase was produced in the activities of glucose-6-phosphate dehydrogenase and malic enzyme. These increases can be interpreted in terms of an enhancement of the NADPH-dependent detoxifying processes and of nucleic acid synthesis and repair.  相似文献   
63.
To optimize the conversion of carbohydrates to ethanol, strains of several Saccharomyces species were examined for the ability to grow and ferment in a range of sucrose and ethanol concentrations. A total of 632 wine yeasts, most of them isolated from wineries in Andalusia and Extremadura, southwestern Spain, were subjected to screening and selection. Growth and fermentative capacity in different ethanol and sucrose concentrations varied from one strain to another. There was no correlation between growth and fermentative capacity. The best 35 strains grew in 15% ethanol and fermented in 18% ethanol. Ethanol accumulated, although at a reduced rate, after the cells stopped growing. Most yeast strains were highly fermentative in 50% sucrose. Some of them effectively utilized the carbohydrates of the culture, yielding final ethanol concentrations of > 14%. Of the 35 selected strains, 16 were promising for genetic analysis and breeding because of their capacity to sporulate. These strains were homothallic, and their spores were viable. The meiotic products analyzed so far were also homothallic.  相似文献   
64.
65.
66.
67.
The antibiotic activity of the antifungal substance mucidin was compared with the activity of nystatin and pimaricin. The antibiotics were tested by the plate method using 19 fungal species, mainly phytopathogenic ones. Toward 14 species, mucidin was ten times more active than nystatin and pimaricin, toward 5 species the activities were roughly the same. The antibiotics differed also in the sharpness of the inhibition zone boundaries.  相似文献   
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