全文获取类型
收费全文 | 2651篇 |
免费 | 255篇 |
国内免费 | 5篇 |
专业分类
2911篇 |
出版年
2022年 | 17篇 |
2021年 | 27篇 |
2020年 | 23篇 |
2019年 | 21篇 |
2018年 | 41篇 |
2017年 | 48篇 |
2016年 | 54篇 |
2015年 | 86篇 |
2014年 | 109篇 |
2013年 | 170篇 |
2012年 | 171篇 |
2011年 | 156篇 |
2010年 | 121篇 |
2009年 | 90篇 |
2008年 | 99篇 |
2007年 | 81篇 |
2006年 | 76篇 |
2005年 | 77篇 |
2004年 | 68篇 |
2003年 | 67篇 |
2002年 | 80篇 |
2001年 | 82篇 |
2000年 | 82篇 |
1999年 | 74篇 |
1998年 | 49篇 |
1997年 | 31篇 |
1996年 | 36篇 |
1995年 | 44篇 |
1994年 | 29篇 |
1993年 | 39篇 |
1992年 | 51篇 |
1991年 | 51篇 |
1990年 | 53篇 |
1989年 | 37篇 |
1988年 | 40篇 |
1987年 | 34篇 |
1986年 | 23篇 |
1985年 | 34篇 |
1984年 | 44篇 |
1983年 | 44篇 |
1982年 | 31篇 |
1981年 | 36篇 |
1980年 | 24篇 |
1979年 | 25篇 |
1978年 | 30篇 |
1977年 | 33篇 |
1976年 | 24篇 |
1974年 | 22篇 |
1973年 | 17篇 |
1972年 | 19篇 |
排序方式: 共有2911条查询结果,搜索用时 0 毫秒
1.
2.
The mechanisms controlling early adenovirus gene expression in vivo have been studied using inhibitors of protein synthesis. When inhibitors were added shortly before or at the onset of infection, viral mRNA from all early regions was transcribed, spliced and accumulated over a 7 hr period. After longer pretreatment, accumulation of several early mRNAs were suppressed. Addition of inhibitors 1 hr after infection enhanced the accumulation of viral mRNA in the cytoplasm. Translation of early mRNA selected on adenovirus DNA in a cell-free system reflected the amount of viral mRNA present. A viral coded product may therefore control accumulation of viral mRNA.A different pattern emerged when inhibitors of protein synthesis were removed at 5 hr postinfection and cells were pulse-labeled in vivo. If inhibitors were introduced at or before infection, early viral proteins were synthesized only after a lag of 1–3 hr. However, if treatment was introduced 1 hr post-infection, reversion of the protein synthesis block was instantaneous. It appears that protein synthesis inhibitors reveal an in vivo translational block for viral mRNA. This block could be overcome by preinfection with a related virus. Furthermore, no block was observed in a virus-transformed human embryonic kidney cell line (293) which expresses early region 1 of the viral genome. Viral gene product(s) encoded in early region 1 may control translation of early adenovirus messenger RNA in vivo. 相似文献
3.
Elisabeth Hansson Ingemar Jacobson Richard Venema Åke Sellström 《Journal of neurochemistry》1980,34(3):569-573
Abstract: The lipophilic cation [3 H]triphenylrnethylphosphonium bromide ([3 H]TPMP+ ) was investigated as a measure of the membrane potential of synaptosomes. Conditions under which [3 H]TPMP+ achieved an equilibrium distribution were tested. The toxicity of TPMP has been studied relative to its inhibitory effects on [3 H]y-aminobutyric acid ([3 H]GABA) transport. In some experiments the distribution of 86 RbZ+ and [3 H]TPMP+ was changed upon incubation in the presence of elevated levels of K+ , ouabain, or KCN, or at 0°C in a way that would be expected from the membrane potential. In normal incubation conditions a membrane potential of ∼−60 mv was calculated. 相似文献
4.
5.
6.
7.
Differential permeabilization of membranes by saponin treatment of isolated rat hepatocytes. Release of secretory proteins. 总被引:10,自引:1,他引:9
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)
Monolayer cultures of rat hepatocytes were treated with increasing concentrations of saponin (prepared from Gypsophila plants) for 30 min at 6 degrees C. Differential permeabilization of the intracellular membranes could be demonstrated: at 0.040 mg of saponin/ml the plasma membrane was permeabilized, as assessed by the release of 50% of the total cellular amount of lactate dehydrogenase, and at 0.20 mg/ml the endoplasmic reticulum was permeabilized, as measured by the release of 50% of pulse-35S-labelled albumin. The Golgi complex was permeabilized at an intermediate saponin concentration, as indicated by the release of homogeneously 35S-labelled albumin; about half the intracellular albumin is located in this organelle. At 1.0 up to 5.0 mg of saponin/ml 90-95% of the radioactively labelled albumin was released. Even at 5.0 mg/ml less than 10% of the membrane of the endoplasmic reticulum was solubilized, as judged by the degree of release of a membrane-bound enzyme specific for this organelle. These results demonstrate the usefulness of saponin as a tool for investigating the interior of different intracellular compartments. 相似文献
8.
G D Eytan B Persson A Ekebacke J Rydstr?m 《The Journal of biological chemistry》1987,262(11):5008-5014
The interaction between pure transhydrogenase and ATPase (Complex V) from beef heart mitochondria was investigated with transhydrogenase-ATPase vesicles in which the two proteins were co-reconstituted by dialysis or dilution procedures. In addition to phosphatidylcholine and phosphatidylethanolamine, reconstitution required phosphatidylserine and lysophosphatidylcholine. Transhydrogenase-ATPase vesicles catalyzed a 20-30-fold stimulation of the reduction of NADP+ or thio-NADP+ by NADH and a 70-fold shift of the apparent equilibrium expressed as the nicotinamide nucleotide ratio [NADPH][NAD+]/[NADP+][NADH]. In both of these respects, the transhydrogenase-ATPase vesicles were severalfold more efficient than beef heart submitochondrial particles. By measuring the ATP-driven transhydrogenase and the oligomycin-sensitive ATPase activities simultaneously and under the same conditions at low ATP concentrations, i.e. below 15 microM, the ATP-driven transhydrogenase/oligomycin-sensitive ATPase activity ratio was found to be about 3. This value is consistent with the stoichiometries of three protons translocated per ATP hydrolyzed and one proton translocated per NADPH formed and with a mechanism where the two enzymes interact through a delocalized proton-motive force. 相似文献
9.
Lennart Persson 《Environmental Biology of Fishes》1987,18(3):235-239
Synopis Reproductively developed male fathead minnows, Pimephales promelas, exhibited courtship behaviour in the presence of female conspecifies under laboratory conditions. Male courtship consisted of several distinctive and visually conspicuous behaviours directed toward females, including approach, display, and two contact behaviours, as well as leading behaviour from the female to a suitable spawning site. An ovulated condition in females was not necessary to generate male courtship behaviour; in fact, the amount of courtship exhibited by males may depend inversely on the readiness of females to spawn. 相似文献
10.
C Lindbladh M Persson L Bülow S Stahl K Mosbach 《Biochemical and biophysical research communications》1987,149(2):607-614
The gene encoding human proinsulin has been fused in-frame with the E. coli alkaline phosphatase gene (pho A) (EC 3.1.3.1). Two constructions are described. One construction consists of the entire proinsulin gene fused to the 5'-terminal end of pho A. In the other construction a 42 base pair DNA fragment has been deleted from the 3'-terminal end of the proinsulin gene. The two purified fusion proteins are enzymatically active showing a specific activity of 10-15 U/mg and 18-25 U/mg, respectively. The first construction exhibited insulin antigenicity and was used to design a simple competitive ELISA for insulin. The lower detection limit was found to be at least 2.5 ng/ml. Both fusion proteins were also shown to have potential for use in a competitive ELISA for proinsulin. 相似文献