全文获取类型
收费全文 | 735457篇 |
免费 | 83127篇 |
国内免费 | 853篇 |
出版年
2018年 | 7032篇 |
2017年 | 6752篇 |
2016年 | 9392篇 |
2015年 | 12853篇 |
2014年 | 15076篇 |
2013年 | 21322篇 |
2012年 | 25244篇 |
2011年 | 26153篇 |
2010年 | 17162篇 |
2009年 | 15132篇 |
2008年 | 22797篇 |
2007年 | 23680篇 |
2006年 | 22155篇 |
2005年 | 21160篇 |
2004年 | 21137篇 |
2003年 | 20119篇 |
2002年 | 19627篇 |
2001年 | 30468篇 |
2000年 | 30555篇 |
1999年 | 24214篇 |
1998年 | 9119篇 |
1997年 | 9119篇 |
1996年 | 8779篇 |
1995年 | 8397篇 |
1994年 | 8161篇 |
1993年 | 8065篇 |
1992年 | 20350篇 |
1991年 | 19823篇 |
1990年 | 19487篇 |
1989年 | 18913篇 |
1988年 | 17554篇 |
1987年 | 16742篇 |
1986年 | 15642篇 |
1985年 | 15587篇 |
1984年 | 13013篇 |
1983年 | 11445篇 |
1982年 | 8804篇 |
1981年 | 7938篇 |
1980年 | 7431篇 |
1979年 | 12568篇 |
1978年 | 9913篇 |
1977年 | 9068篇 |
1976年 | 8474篇 |
1975年 | 9562篇 |
1974年 | 10350篇 |
1973年 | 10218篇 |
1972年 | 9193篇 |
1971年 | 8598篇 |
1970年 | 7295篇 |
1969年 | 7121篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
There is an urgent need for effective prophylactic measures against Mycobacterium tuberculosis (Mtb) infection, particularly given the highly variable efficacy of Bacille Calmette-Guerin (BCG), the only licensed vaccine against tuberculosis (TB). Most studies indicate that cell-mediated immune responses involving both CD4+ and CD8+ T cells are necessary for effective immunity against Mtb. Genetic vaccination induces humoral and cellular immune responses, including CD4+ and CD8+ T-cell responses, against a variety of bacterial, viral, parasitic and tumor antigens, and this strategy may therefore hold promise for the development of more effective TB vaccines. Novel formulations and delivery strategies to improve the immunogenicity of DNA-based vaccines have recently been evaluated, and have shown varying degrees of success. In the present study, we evaluated DNA-launched Venezuelan equine encephalitis replicons (Vrep) encoding a novel fusion of the mycobacterial antigens α-crystallin (Acr) and antigen 85B (Ag85B), termed Vrep-Acr/Ag85B, for their immunogenicity and protective efficacy in a murine model of pulmonary TB. Vrep-Acr/Ag85B generated antigen-specific CD4+ and CD8+ T cell responses that persisted for at least 10 wk post-immunization. Interestingly, parenterally administered Vrep-Acr/Ag85B also induced T cell responses in the lung tissues, the primary site of infection, and inhibited bacterial growth in both the lungs and spleens following aerosol challenge with Mtb. DNA-launched Vrep may, therefore, represent an effective approach to the development of gene-based vaccines against TB, particularly as components of heterologous prime-boost strategies or as BCG boosters. 相似文献
992.
F. Marsolat D. Tromson N. Tranchant P. Bergonzo F. Moignau L. De Carlan D. Lazaro M. Agelou C. Bassinet C. Huet S. Derreumaux M. Chea G. Boisserie I. Buchheit V. Marchesi 《Physica medica : PM : an international journal devoted to the applications of physics to medicine and biology : official journal of the Italian Association of Biomedical Physics (AIFB)》2012
993.
994.
Molecular determinants of visual pigment function. 总被引:1,自引:0,他引:1
M L Applebury 《Current opinion in neurobiology》1991,1(2):263-269
Mutagenesis studies and comparisons of natural variants of rhodopsin and related visual pigments have led to new insights concerning photoreceptor function. The studies identify domains important for receptor folding, the residues that set the wavelength of absorption for the ligand 11-cis retinal, and residues, that when mutated, trigger the cell death of photoreceptors. 相似文献
995.
996.
A crown-of-thorns starfish control program was conducted at Grub Reef (central Great Barrier Reef) in an area (0.64 km2) which encompassed 53 individual patch reefs. During a two week period, 15 divers injected 3175 starfish with copper sulphate. The program was considered unsuccessful. Although starfish abundance had declined significantly after the control efforts, biological surveys indicated that a relatively large number of starfish remained. The surveys also indicated a general decline in the number of starfish along the reef perimeter, outside the control area. The total cost of the control program was $35 per starfish. These results have important implications for the implementation of future control programs and highlight the need to undertake before and after biological surveys to assess the effectiveness of the control efforts. 相似文献
997.
Léniz A. Portillo M. P. Fernández-Quintela Alfredo Macarulla M. T. Sarasua-Miranda A. del Hoyo M. Díez-López I. 《Journal of physiology and biochemistry》2019,75(3):311-319
Journal of Physiology and Biochemistry - Infants born small for gestational age (SGA) are at increased risk of perinatal morbidity, persistent short stature, and metabolic alterations in later... 相似文献
998.
999.
1000.