全文获取类型
收费全文 | 2284篇 |
免费 | 150篇 |
国内免费 | 1篇 |
出版年
2018年 | 19篇 |
2017年 | 15篇 |
2016年 | 27篇 |
2015年 | 42篇 |
2014年 | 49篇 |
2013年 | 79篇 |
2012年 | 89篇 |
2011年 | 92篇 |
2010年 | 65篇 |
2009年 | 53篇 |
2008年 | 93篇 |
2007年 | 95篇 |
2006年 | 112篇 |
2005年 | 109篇 |
2004年 | 102篇 |
2003年 | 85篇 |
2002年 | 94篇 |
2001年 | 33篇 |
2000年 | 28篇 |
1999年 | 46篇 |
1998年 | 35篇 |
1997年 | 41篇 |
1996年 | 28篇 |
1995年 | 34篇 |
1994年 | 47篇 |
1993年 | 41篇 |
1992年 | 41篇 |
1991年 | 47篇 |
1990年 | 47篇 |
1989年 | 39篇 |
1988年 | 32篇 |
1987年 | 34篇 |
1986年 | 38篇 |
1985年 | 36篇 |
1984年 | 29篇 |
1983年 | 35篇 |
1982年 | 39篇 |
1981年 | 35篇 |
1980年 | 30篇 |
1979年 | 39篇 |
1978年 | 24篇 |
1977年 | 16篇 |
1976年 | 19篇 |
1975年 | 19篇 |
1974年 | 15篇 |
1973年 | 22篇 |
1972年 | 18篇 |
1971年 | 12篇 |
1970年 | 14篇 |
1965年 | 14篇 |
排序方式: 共有2435条查询结果,搜索用时 31 毫秒
121.
Summary The streptococcal plasmid ERL1 determining inducible resistance to erythromycin, lincomycin, and staphylomycin S was isolated by dye-buoyant density centrifugation and shown to have a molecular weight of about 17.5 Mdal, as revealed by sedimentation through neutral sucrose gradients. In SM60 cells entering the stationary phase its covalently closed circular form was present to the extent of 5 copies per chromosomal genome equivalent. ERL1 was subject to the DNA restriction and modification mechanism discovered in strain 56188. It did not apear to exercise restriction of phage DNA but mediated a partial release of the restricted growth of A25. 相似文献
122.
Ca2+ accumulation at pH 6.8 by isolated rabbit heart microsomes derived chiefly from sarcoplasmic reticulum was investigated by a quench-flow technique. The reaction was terminated at preset times by addition to the reaction mixture of an equal volume of 10 to 50 mM ethyleneglycol-bis-(β-aminoethyl ether)-N,N′-tetraacetic acid buffered at pH 6.0. The initial velocity of Ca2+ accumulation by microsomal preparations exhibiting a steady state Ca2+ accumulation of 25.6 nmol Ca2+/mg increased from 3.67 to 33.4 nmol Ca2+/mg · s as the free Ca2+ concentration was raised from 0.2 to 18.9 μM. Preincubation of the cardiac microsomes with a partly purified soluble cardiac cyclic AMP-dependent protein kinase, MgATP, and cyclic AMP lead to a significant increase in the initial Ca2+ accumulation rate. The amounts of Ca2+ that were found to accumulate in the first 200 ms of the reaction are comparable to the quantities of the ion that according to literature data need to be removed from the myofilaments and the myoplasm for induction of relaxation of the myocardial fibers. 相似文献
123.
Incorporation of isolated chromosomes and induction of hypoxanthine phosphoribosyltransferase in Chinese hamster cells. 总被引:1,自引:0,他引:1
Evidence is presented for the uptake of radioactive-labeled isolated Chinese hamster chromosomes following incubation with Chinese hamster cells. Metaphases were found which contained radioactive labeled chromosomes in a very low frequency, and in some of the labeled chromosomes only one chromatid was labeled. Incubation of hypoxanthine phosphoribosyltransferas (HPRT)-deficient Chinese hamster cells with chromosomes isolated from HPRT+ Chinese hamster or human cells resulted in the appearance of HPRT+ cells. Clones derived from these cells were isolated in HAT medium. Cells in mitosis during incubation with the chromosomes yielded thr-e times more HPRT+ clones than did cells in interphase. The intraspecies combination involving recipient cells and chromosomes from Chinese hamster origin yielded significantly higher numbers of HPRT+ clones than did the interspecies system using human chromsomes and Chinese hamster recipient cells (5 X 10(-5) and 6 X 10(-6) respectively). Electrophoresis of HPRT from Chinese hamster cells treated with human chromosomes revealed the pattern of the human enzyme. 相似文献
124.
125.
Horst Drawert 《Protoplasma》1938,29(1):206-227
Ohne Zusammenfassung 相似文献
126.
127.
The complex C60Pt[P(OPh)3]2 displays C60 ππ* intraligand bands in the UV-Vis region and a long-wavelength absorption at λmax = 770 nm which is assigned to a metal-to-ligand charge transfer (MLCT) transition from platinum to fullerene. The irradiation of the complex leads to the population of the reactive MLCT state and subsequently to the dissociation (C60Pt[P(OPh)3]2 → C60 + Pt[P(OPh)3]2) in the primary photochemical step. Product formation takes place by the interception of Pt[P(OPh)3]2 with suitable scavengers such as CHCl3 or O2. 相似文献
128.
129.
130.