全文获取类型
收费全文 | 41844篇 |
免费 | 3704篇 |
国内免费 | 205篇 |
专业分类
45753篇 |
出版年
2018年 | 495篇 |
2017年 | 484篇 |
2016年 | 627篇 |
2015年 | 702篇 |
2014年 | 906篇 |
2013年 | 1078篇 |
2012年 | 1225篇 |
2011年 | 1261篇 |
2010年 | 855篇 |
2009年 | 862篇 |
2008年 | 1173篇 |
2007年 | 1165篇 |
2006年 | 1179篇 |
2005年 | 1003篇 |
2004年 | 962篇 |
2003年 | 910篇 |
2002年 | 886篇 |
2001年 | 2775篇 |
2000年 | 2455篇 |
1999年 | 1799篇 |
1998年 | 612篇 |
1997年 | 525篇 |
1996年 | 470篇 |
1995年 | 400篇 |
1994年 | 386篇 |
1992年 | 1279篇 |
1991年 | 1158篇 |
1990年 | 1096篇 |
1989年 | 1043篇 |
1988年 | 928篇 |
1987年 | 922篇 |
1986年 | 802篇 |
1985年 | 793篇 |
1984年 | 563篇 |
1983年 | 513篇 |
1982年 | 366篇 |
1979年 | 630篇 |
1978年 | 451篇 |
1977年 | 414篇 |
1976年 | 368篇 |
1975年 | 494篇 |
1974年 | 575篇 |
1973年 | 553篇 |
1972年 | 571篇 |
1971年 | 548篇 |
1970年 | 520篇 |
1969年 | 526篇 |
1968年 | 426篇 |
1967年 | 373篇 |
1966年 | 409篇 |
排序方式: 共有10000条查询结果,搜索用时 14 毫秒
141.
The 13C NMR spectra of geosmin, selina-4(14),7(11)-diene-99-ol and two dihydroeudesmol isomers have been obtained and the individual resonances assigned. Several different empirical correlations developed by others have been combined in simple calculations to predict chemical shift values for sesquiterpenols of the eudesmane group. 相似文献
142.
143.
144.
145.
146.
147.
Activity of phosphate-dissolving bacteria in Egyptian soils 总被引:1,自引:0,他引:1
S. M. Taha S. A. Z. Mahmoud A. Halim El-Damaty A. M. Abd El-Hafez 《Plant and Soil》1969,31(1):149-160
148.
We report the first use of an emission probe based on the Cu(I)-thiolate chromophore, for the direct observation of copper metallothionein located in samples of rat liver. Elevated synthesis of Cu-MT in the rat liver was induced by subcutaneous injections of a series of aqueous CuCl2 solutions containing increasing amounts of Cu(II). Luminescence intensity in the 600 nm region, detected from frozen solutions of Cu-MT and from slices of the liver frozen at 77 K, following excitation in the 300 nm region, was dependent on the concentration of the Cu(II) used in the inducing solution. No such luminescence intensity was found for control samples obtained from the livers of rats not exposed to copper salts. It is suggested that this new method will allow direct visualization of Cu-MT in tissue where genetic disorders impare copper metabolism. 相似文献
149.
150.
R I Krylova E Ia Balaeva N A Voskanian E K Dzhikidze Z V Shevtsova 《Biulleten' eksperimental'no? biologii i meditsiny》1977,84(9):368-372
The results of pathomorphological investigation of the disease in small laboratory animals experimentally induced by the EMC-70 strain of encephalomyocarditis virus isolated from monkeys are presented. Irrespective of the mode of virus injection, the newborn and juvenile mice developed some lesions in the brown fat, transverse-striated muscles, as well as in the brain and heart. In guinea pigs the changes were characterized by the development of severe myocarditis and encephalitis accompanied by viral antigen accumulation. The disease induced by the EMC-70 strain could not be differentiated from the Coxsackie infection by the pathomorphological data. This fact should be taken into consideration in solving some problems pertinent to pathoanatomical diagnosis of viral diseases. 相似文献