全文获取类型
收费全文 | 195篇 |
免费 | 35篇 |
出版年
2022年 | 4篇 |
2021年 | 10篇 |
2020年 | 3篇 |
2019年 | 1篇 |
2018年 | 2篇 |
2017年 | 5篇 |
2016年 | 9篇 |
2015年 | 6篇 |
2014年 | 19篇 |
2013年 | 9篇 |
2012年 | 17篇 |
2011年 | 16篇 |
2010年 | 9篇 |
2009年 | 8篇 |
2008年 | 7篇 |
2007年 | 12篇 |
2006年 | 9篇 |
2005年 | 8篇 |
2004年 | 7篇 |
2003年 | 3篇 |
2002年 | 6篇 |
2001年 | 3篇 |
2000年 | 3篇 |
1999年 | 2篇 |
1998年 | 3篇 |
1997年 | 1篇 |
1995年 | 2篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1992年 | 2篇 |
1991年 | 2篇 |
1990年 | 2篇 |
1989年 | 4篇 |
1988年 | 5篇 |
1987年 | 5篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1978年 | 2篇 |
1976年 | 2篇 |
1975年 | 1篇 |
1974年 | 3篇 |
1973年 | 2篇 |
1972年 | 2篇 |
1970年 | 1篇 |
1969年 | 1篇 |
1968年 | 1篇 |
1965年 | 1篇 |
排序方式: 共有230条查询结果,搜索用时 46 毫秒
41.
5S-rRNA genes in rice embryos 总被引:3,自引:0,他引:3
42.
43.
Summary
Cephalosporium acremonium cells were immobilized in calcium alginate beads. Immobilized cells were used to produce -lactam antibiotics in rest medium under various oxygen concentrations, and the results were compared with free cell performance. Cell growth rate of immobilized cells was 35% of the growth rate of free cells. -Lactam antibiotic production rate of immobilized cells was also limited by mass transfer of oxygen. -Lactam antibiotic production rate of immobilized cells was 70% of that of free cells at oxygen saturation condition (i.e., 0.27 mM O2). Specific antibiotic production of immobilized cells was about 200% of that of free cells at 0.27 mM O2. 相似文献
44.
Summary It was determined thatCephalosporium acremonium, an oxygenconsuming fungus, had a symbiotic relationship withChlorella pyrenoidosa, an oxygen-generating alga. The fungus and the alga were coimmobilized by entrapment in calcium alginate beads. The production rate of -lactam antibiotics was evaluated at various ratios of the fungus and the alga cells in the free and immobilized states. When the ratio of fungus to alga was one to eight in free mixed culture, the production rate of -lactam antibiotics was 240% of the rate in the presence of fungus alone in the free state. In coimmobilized cell system, the increased amount was 370% in comparison with immobilized fungus alone. 相似文献
45.
Summary The oxygen effect on the production of -lactam antibiotics was investigated whenCephalosporium acremonium was immobilized in calcium alginate. Theoretical effectiveness factors were calculated and compared with experimental ones. The approximate expressions of effectiveness factors reported in the literature were compared with the numerically obtained solutions to provide the best approximated expression for immobilizedC. acremonium cells. Yamane's approximate expression of effectiveness factor was best fit with the solutions numerically obtained in this investigation. 相似文献
46.
A lethal myeloproliferative syndrome in mice transplanted with bone marrow cells infected with a retrovirus expressing granulocyte-macrophage colony stimulating factor. 总被引:32,自引:4,他引:28 下载免费PDF全文
Murine bone marrow cells infected with a novel recombinant retrovirus, MPZen(GM-CSF), were engrafted into lethally irradiated recipients. The transplanted animals developed extremely high circulating levels of GM-CSF (up to 3 x 10(5) units/ml), and greatly elevated peripheral nucleated cell counts (up to 110 x 10(6) per ml). Their haemopoietic tissues contained GM-CSF proviral DNA and produced substantial levels of GM-CSF. The mice died within 4 weeks of transplantation with extensive neutrophil and macrophage infiltration of the spleen, lung, liver and peritoneal cavity and significant infiltration of both heart and skeletal muscle by neutrophils, macrophages and eosinophils. The thymus and lymph nodes were deficient in lymphoid cells. No disease occurred when infected cells from haemopoietic tissues of the primary transplanted animals were injected into normal or sub-lethally irradiated mice. Dysregulated GM-CSF expression by haemopoietic cells thus produces a fatal albeit non-neoplastic myeloproliferative syndrome. 相似文献
47.
Pil Jung Kang Laure Béven Seethalakshmi Hariharan Hay-Oak Park 《Molecular biology of the cell》2010,21(17):3007-3016
Cell polarization occurs along a single axis that is generally determined in response to spatial cues. In budding yeast, the Rsr1 GTPase and its regulators direct the establishment of cell polarity at the proper cortical location in response to cell type–specific cues. Here we use a combination of in vivo and in vitro approaches to understand how Rsr1 polarization is established. We find that Rsr1 associates with itself in a spatially and temporally controlled manner. The homotypic interaction and localization of Rsr1 to the mother-bud neck and to the subsequent division site are dependent on its GDP-GTP exchange factor Bud5. Analyses of rsr1 mutants suggest that Bud5 recruits Rsr1 to these sites and promotes the homodimer formation. Rsr1 also exhibits heterotypic interaction with the Cdc42 GTPase in vivo. We show that the polybasic region of Rsr1 is necessary for the efficient homotypic and heterotypic interactions, selection of a proper growth site, and polarity establishment. Our findings thus suggest that dimerization of GTPases may be an efficient mechanism to set up cellular asymmetry. 相似文献
48.
49.
50.
Adam Doern Xianjun Cao Arlene Sereno Christopher L. Reyes Angelina Altshuler Flora Huang Cathy Hession Albert Flavier Michael Favis Hon Tran Eric Ailor Melissa Levesque Tracey Murphy Lisa Berquist Susan Tamraz Tracey Snipas Ellen Garber William S. Shestowsky Rachel Rennard Christilyn P. Graff Xiufeng Wu William Snyder Lindsay Cole David Gregson Michael Shields Steffan N. Ho Mitchell E. Reff Scott M. Glaser Jianying Dong Stephen J. Demarest Kandasamy Hariharan 《The Journal of biological chemistry》2009,284(15):10254-10267