全文获取类型
收费全文 | 638篇 |
免费 | 70篇 |
出版年
2021年 | 5篇 |
2020年 | 4篇 |
2019年 | 8篇 |
2018年 | 5篇 |
2017年 | 13篇 |
2016年 | 20篇 |
2015年 | 35篇 |
2014年 | 25篇 |
2013年 | 39篇 |
2012年 | 30篇 |
2011年 | 20篇 |
2010年 | 16篇 |
2009年 | 28篇 |
2008年 | 25篇 |
2007年 | 29篇 |
2006年 | 29篇 |
2005年 | 21篇 |
2004年 | 26篇 |
2003年 | 16篇 |
2002年 | 19篇 |
2001年 | 20篇 |
2000年 | 13篇 |
1999年 | 21篇 |
1998年 | 15篇 |
1997年 | 18篇 |
1996年 | 9篇 |
1995年 | 7篇 |
1994年 | 9篇 |
1993年 | 8篇 |
1992年 | 13篇 |
1991年 | 11篇 |
1990年 | 11篇 |
1989年 | 4篇 |
1988年 | 8篇 |
1987年 | 10篇 |
1986年 | 7篇 |
1985年 | 7篇 |
1984年 | 8篇 |
1983年 | 15篇 |
1982年 | 5篇 |
1981年 | 6篇 |
1980年 | 7篇 |
1979年 | 10篇 |
1978年 | 7篇 |
1977年 | 7篇 |
1970年 | 3篇 |
1969年 | 3篇 |
1967年 | 4篇 |
1965年 | 3篇 |
1963年 | 3篇 |
排序方式: 共有708条查询结果,搜索用时 15 毫秒
701.
Frederick A. Rainey Peter Schumann Helmut Prauser Rosemary Toalster Erko Stackebrandt 《FEMS microbiology letters》1993,109(2-3):263-267
Abstract The 16S rDNA of Sporichthya polymorpha was PCR amplified from genomic DNA and almost completely sequenced using the dideoxy dye-terminator sequencing approach and automated DNA analysis. The primary structure was compared to the homologous molecule from 160 representatives of 37 genera of the order Actinomycetales . No higher similarity than 91.7% was found and the phylogenetic tree shows this morphologically unique organism to from an individual line of descent outside the main radiation of spore- and mycelium-forming organisms. 相似文献
702.
W G?hde M Meistrich R Meyn J Schumann D Johnston B Barlogie 《The journal of histochemistry and cytochemistry》1979,27(1):470-473
The effect of adriamycin on cell cycle phase progression of CHO cells synchronized into the various phases of the cell cycle by elutriation was investigated by high resolution pulse cytophotometry. Cells treated in all phases of the cell cycle showed delay in their subsequent progression. In addition to the wellknown block of cells in the G2-phase, a delay in passage of cells from G1 to S and a decreased rate of transit through the S-phase were observed. A broadening of the DNA distributions of the treated cells was observed after cell division indicating induction of chromosomal abnormalities. 相似文献
703.
Julie Sudduth-Klinger Muhammad Schumann Phyllis Gardner Donald G. Payan 《Cellular and molecular neurobiology》1992,12(5):379-395
1. We have transfected the rat substance P receptor (SPR) cDNA into the leukemic T-lymphocyte cell line Jurkat (J-wt) in order to study the effects of substance P (SP) on lymphocyte signaling mechanisms and the resultant neuropeptide-induced immunological changes. 2. The SPR cDNA was transfected into J-wt by the method of electroporation. Clones expressing SPRs were selected using a functional assay that measured SP-induced mobilization of intracellular Ca2+ ([Ca2+]i) in a fluorescence activated cell sorter (FACS) and by their expression of specific 125I-SP binding. 3. One clone, J-SPR, was identified and shown by Northern blot and 125I-SP saturation binding techniques to express the 2.2-kb SPR message and approximately 50,000 SPRs/cell with a Kd of 0.3 nM, respectively. Stimulation of J-SPR by SP resulted in the rapid mobilization of [Ca2+]i. This response was dose dependent in the range 10(-11)-10(-6) M SP and was maximal at 10(-7) M SP, with an EC50 of 0.3-0.5 nM SP. We further demonstrated that the SPR is rapidly desensitized following SP stimulation and by activation of the cell's T-cell receptor (TCR). Whole-cell patch-clamp experiments on J-SPR show that SP stimulation induces a Cl- current by a Ca2+ mediated process dependent on Ca2+/calmodulin-dependent protein kinase (CaMK). 4. Stimulation of J-SPR by SP results in changes in the cell surface expression of a number of molecules that play important roles in cell adhesion and activation: the expression of LFA-1 is decreased, and CD2 and IL-2 receptors are increased by 30 min, 6 hr, and 24 hr, respectively, following stimulation, as assessed by antibody staining in a FACS. 5. The expression of functional SPRs in Jurkat lymphocytes will not permit a detailed examination of how the activation of SPRs result in altered immune responses and further elucidate the role this neuropeptide receptor plays in inflammation. 相似文献
704.
705.
Psychrophilic microorganisms and their cold-active enzymes 总被引:2,自引:0,他引:2
JE Brenchley 《Journal of industrial microbiology & biotechnology》1996,17(5-6):432-437
706.
707.
In the shallow eutrophic waters of the Darss-Zingst-ecosystem (Baltic Sea) wind induced mixing of the water column, and resuspension
of sediment is an important phenomenon. Incubation experiments (7 days) with natural water were performed in the laboratory
under simulated mixing conditions in order to assess the effects on abundance, biomass and activity of bacteria, heterotrophic
nanoflagellates and ciliates in the water column and upper bottom layers.
Under calm mixing conditions a bottom layer developed, rich in organic aggregates. Bacterial biomass increased through increase
of bacteria abundance and doubled cell volume. Consequently, biomass of flagellates and, more pronounced, of ciliates increased.
The bottom layer, comprising only 15% of the incubated volume, containedca. 60% of the bacterial biomass and ca. 55% of production, 75 and 95% of flagellate biomass, and ca. 70% of ciliate biomass.
It is concluded that bottom layers rich in organic aggregates, although not being present permanently, play an important role
in the shallow Darss-Zingst-ecosystem. 相似文献
708.
Cyclins are indispensable elements of the cell cycle and derangement of their function can lead to cancer formation. Recent studies have also revealed more mechanisms through which cyclins can express their oncogenic potential. This review focuses on the aberrant expression of G1/S cyclins and especially cyclin D and cyclin E; the pathways through which they lead to tumour formation and their involvement in different types of cancer. These elements indicate the mechanisms that could act as targets for cancer therapy. 相似文献