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   47835篇
  免费   3761篇
  国内免费   7篇
  51603篇
  2023年   284篇
  2022年   524篇
  2021年   1046篇
  2020年   710篇
  2019年   960篇
  2018年   1217篇
  2017年   1140篇
  2016年   1589篇
  2015年   2278篇
  2014年   2440篇
  2013年   3182篇
  2012年   3884篇
  2011年   3701篇
  2010年   2357篇
  2009年   2115篇
  2008年   2719篇
  2007年   2662篇
  2006年   2518篇
  2005年   2282篇
  2004年   2140篇
  2003年   1982篇
  2002年   1874篇
  2001年   724篇
  2000年   649篇
  1999年   611篇
  1998年   572篇
  1997年   371篇
  1996年   349篇
  1995年   341篇
  1994年   252篇
  1993年   258篇
  1992年   315篇
  1991年   264篇
  1990年   253篇
  1989年   232篇
  1988年   194篇
  1987年   190篇
  1986年   194篇
  1985年   167篇
  1984年   215篇
  1983年   154篇
  1982年   170篇
  1981年   168篇
  1980年   142篇
  1979年   118篇
  1978年   116篇
  1977年   90篇
  1975年   71篇
  1974年   114篇
  1973年   73篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
72.
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   
73.
74.
The effect of the Abortion Act on gynaecological work in one provincial teaching hospital is that despite an increase in patient turnover of 45% the waiting list has increased by 200%. It is suggested that the Act has had little effect on the birth rate or illegitimacy and that there may have been an increase in criminal abortion.  相似文献   
75.
76.
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   
77.
78.
79.
Brian Snoad 《Genetica》1966,37(1):247-254
By appropriate genetical studies using reciprocal translocation stocks it has been possible to confirmLamprecht's evidence that inPisum there are seven linkage groups. Lamm's evidence for six linkage groups has been shown to be due to incomplete knowledge of the chromosomal structure of certain interchange lines.It is suggested thatLamprecht's system of chromosomal nomenclature should be universally adopted forPisum.Lamm &Miravelle's extended tester set has been accordingly renumbered and the intercrossing of the interchange lines completed in order to extend the confirmatory evidence as to their chromosomal constitution.  相似文献   
80.
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