全文获取类型
收费全文 | 5703篇 |
免费 | 607篇 |
国内免费 | 1篇 |
出版年
2021年 | 53篇 |
2019年 | 46篇 |
2018年 | 59篇 |
2017年 | 47篇 |
2016年 | 94篇 |
2015年 | 141篇 |
2014年 | 188篇 |
2013年 | 254篇 |
2012年 | 304篇 |
2011年 | 330篇 |
2010年 | 205篇 |
2009年 | 185篇 |
2008年 | 301篇 |
2007年 | 357篇 |
2006年 | 298篇 |
2005年 | 336篇 |
2004年 | 309篇 |
2003年 | 316篇 |
2002年 | 281篇 |
2001年 | 56篇 |
1999年 | 75篇 |
1998年 | 86篇 |
1997年 | 60篇 |
1996年 | 63篇 |
1995年 | 63篇 |
1994年 | 55篇 |
1993年 | 54篇 |
1992年 | 60篇 |
1991年 | 43篇 |
1990年 | 46篇 |
1989年 | 44篇 |
1988年 | 47篇 |
1987年 | 47篇 |
1986年 | 38篇 |
1985年 | 54篇 |
1984年 | 77篇 |
1983年 | 54篇 |
1982年 | 72篇 |
1981年 | 95篇 |
1980年 | 80篇 |
1979年 | 47篇 |
1978年 | 64篇 |
1977年 | 68篇 |
1976年 | 57篇 |
1975年 | 48篇 |
1974年 | 58篇 |
1973年 | 41篇 |
1970年 | 43篇 |
1969年 | 42篇 |
1967年 | 44篇 |
排序方式: 共有6311条查询结果,搜索用时 15 毫秒
61.
Distribution and metabolism of phenylalanine and tyrosine during tularaemia in the rat (Short Communication)
下载免费PDF全文
![点击此处可从《The Biochemical journal》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Michael C. Powanda Richard E. Dinterman Robert W. Wannemacher Jr. Gerald D. Herbrandson 《The Biochemical journal》1974,144(1):173-176
Tularaemia in rats causes a doubling of the serum phenylalanine/tyrosine ratio and a more than twofold increase in muscle phenylalanine which cannot be accounted for by decreased hepatic phenylalanine hydroxylase (EC 1.14.16.1) activity, but appear to result from a generalized movement of amino acids from muscle to liver during infection. 相似文献
62.
63.
1. In a study of the metabolism of l-[(35)S]methionine in vivo, the labelled sulphur compounds of rat liver and brain were separated first by ion-exchange chromatography into two fractions containing (i) free sulphur amino acids such as methionine, cystathionine, cyst(e)ine and homocyst(e)ine and (ii) glutathione. 2. Two-dimensional paper chromatography with butan-1-ol-acetic acid or propionic acid-water in the first direction and 80% acetone or acetone-ethyl methyl ketone-water in the second direction was found superior to other solvent systems for separating the sulphur amino acids. 3. At 10min. after injection of [(35)S]methionine only a small part of the (35)S was found combined in free methionine or other free sulphur amino acids. 4. Evidence was obtained of the presence of adenosyl[(35)S]methionine and adenosyl[(35)S]homocysteine in perchloric acid extracts of rat liver and brain. 5. The trans-sulphuration pathway was active in brain as well as in liver. 相似文献
64.
C. D. Cook F. Geller G. B. Hutchison P. Gerald F. H. Allen 《American journal of human genetics》1962,14(3):290-294
65.
Gerald Houghton 《Bulletin of mathematical biology》1966,28(4):487-500
A two-dimensional nonlinear integro-differential equation with time-varying coefficients describing the behavior of the fluttering
wing-body systems typical of natural flight mechanisms has been deduced from the Navier-Stokes equation which generalizes
local pressure and velocity distributions in the externally oscillating air field. The resulting equation for the wing forces
is combined with an analogous expression for the forces of gravitation and acceleration associated with the body. The air
acceleration force, not previously considered in bio-physical models of insect and bird flight, is shown to arise from a formal
analysis of unsteady or time-varying contributions to the velocity field, while the square form of the conventional steady
state aerodynamic forces is derived from the intertial terms in the Navier-Stokes equation with the aid of the approximations
of Newtonian impact theory. Previous calculations (Houghton, 1964) have indicated that the contribution to gravitational stability
of air acceleration and aerodynamic life are roughly in the ratio of 3:1. 相似文献
66.
67.
68.
69.
70.