全文获取类型
收费全文 | 12587篇 |
免费 | 1298篇 |
国内免费 | 2篇 |
出版年
2022年 | 103篇 |
2021年 | 170篇 |
2020年 | 121篇 |
2019年 | 143篇 |
2018年 | 173篇 |
2017年 | 159篇 |
2016年 | 245篇 |
2015年 | 381篇 |
2014年 | 447篇 |
2013年 | 590篇 |
2012年 | 612篇 |
2011年 | 666篇 |
2010年 | 480篇 |
2009年 | 399篇 |
2008年 | 603篇 |
2007年 | 589篇 |
2006年 | 498篇 |
2005年 | 508篇 |
2004年 | 482篇 |
2003年 | 440篇 |
2002年 | 457篇 |
2001年 | 283篇 |
2000年 | 355篇 |
1999年 | 265篇 |
1998年 | 165篇 |
1997年 | 148篇 |
1996年 | 136篇 |
1995年 | 130篇 |
1994年 | 116篇 |
1993年 | 97篇 |
1992年 | 220篇 |
1991年 | 195篇 |
1990年 | 203篇 |
1989年 | 165篇 |
1988年 | 208篇 |
1987年 | 175篇 |
1986年 | 142篇 |
1985年 | 179篇 |
1984年 | 154篇 |
1983年 | 135篇 |
1982年 | 138篇 |
1981年 | 105篇 |
1980年 | 108篇 |
1979年 | 146篇 |
1978年 | 123篇 |
1977年 | 111篇 |
1976年 | 116篇 |
1975年 | 103篇 |
1974年 | 112篇 |
1973年 | 97篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
Marjorie Jones Roy W. Keenan 《Biochimica et Biophysica Acta (BBA)/General Subjects》1981,678(3):403-407
A procedure was developed for the detection of 2′,3′-cyclic nucleotide 3′-phosphohydrolase in myelin. This assay was sufficiently sensitive to detect the low levels of 2′,3′-cyclic nucleotide 3′-phosphohydrolase in human erythrocytes. The 2′,3′-cyclic nucleotide 3′-phosphohydrolase of human erythrocytes was determined to be exclusively associated with the inner (cytosolic) side of the membrane. Leaky ghostsand resealed ghosts were assayed for 2′,3′-cyclic nucleotide 3′-phosphohydrolase, (Ca2+/Mg2+-ATPase, and acetylcholinesterase activity, and the 2′,3′-cyclic nucleotide 3′-phosphohydrolase profile is the same as that of the (Ca2+/Mg2+)-ATPase, an established inner membrane maker. 相似文献
22.
23.
Purification of phosphoinositide-specific phospholipase C from a particulate fraction of bovine brain 总被引:6,自引:0,他引:6
The coupling of various agonist receptors to the hydrolysis of phosphoinositides has generated much interest in the nature of the phospholipase C that is activated. Here we report the purification of a bovine brain phospholipase C derived from the particulate fraction. A 1000-fold purification was achieved by a combination of heparin-Sepharose, DEAE-cellulose and gel-permeation chromatography. The purified enzyme appears to be monomeric and under denaturing conditions shows a single staining major polypeptide of molecular mass 154 kDa in SDS gels. The enzyme is specific for phosphoinositides although it shows a marked preference for the polyphosphoinositides. With phosphatidylinositol 4,5-bisphosphate as substrate the enzyme expresses a specific activity of greater than 100 mumol min-1 mg-1. The phospholipase C is activated by Ca2+ (0.1-10 microM). The behaviour of this particulate enzyme is discussed in the context of a agonist-induced phosphatidylinositol hydrolysis. 相似文献
24.
The shikimate/arogenate pathway: Link between carbohydrate metabolism and secondary metabolism 总被引:2,自引:0,他引:2
Roy A. Jensen 《Physiologia plantarum》1986,66(1):164-168
25.
26.
27.
28.
Energy calculations have been carried out on high-symmetry cuboctahedral Ni-Al nanoalloy clusters, of varying composition, with the interatomic interactions modelled by the Gupta many-body potential. Relaxations of cuboctahedral fragments cut from the bulk lattice of Ni3Al, with 13-561 atoms, were undertaken, as were relaxations of high symmetry clusters with 55 and 147 atoms. The lowest energy isomers were found to be dominated by three factors: the tendency toward mixing due to the favourable energy of mixing, ΔmixE; the size difference between nickel and aluminium; and the higher cohesive and surface energy of nickel compared to aluminium. The latter two factors favour Al-segregation to the surface. The most stable Ni:Al composition approaches 3:1 for larger clusters. 相似文献
29.