全文获取类型
收费全文 | 2117篇 |
免费 | 175篇 |
国内免费 | 192篇 |
出版年
2024年 | 1篇 |
2023年 | 26篇 |
2022年 | 68篇 |
2021年 | 105篇 |
2020年 | 68篇 |
2019年 | 109篇 |
2018年 | 102篇 |
2017年 | 72篇 |
2016年 | 89篇 |
2015年 | 141篇 |
2014年 | 145篇 |
2013年 | 134篇 |
2012年 | 203篇 |
2011年 | 166篇 |
2010年 | 98篇 |
2009年 | 80篇 |
2008年 | 107篇 |
2007年 | 86篇 |
2006年 | 75篇 |
2005年 | 72篇 |
2004年 | 39篇 |
2003年 | 48篇 |
2002年 | 54篇 |
2001年 | 35篇 |
2000年 | 32篇 |
1999年 | 48篇 |
1998年 | 19篇 |
1997年 | 31篇 |
1996年 | 20篇 |
1995年 | 29篇 |
1994年 | 30篇 |
1993年 | 16篇 |
1992年 | 35篇 |
1991年 | 22篇 |
1990年 | 19篇 |
1989年 | 14篇 |
1988年 | 11篇 |
1987年 | 4篇 |
1986年 | 4篇 |
1985年 | 7篇 |
1984年 | 11篇 |
1983年 | 6篇 |
1982年 | 1篇 |
1981年 | 2篇 |
排序方式: 共有2484条查询结果,搜索用时 15 毫秒
991.
992.
993.
Fluorescent proteins provide a powerful means to track gene expression and cellular behaviors in the study of model organisms such as mice. Among the new generation of fluorescent protein markers, the monomeric red fluorescent protein mRFP1 is particularly attractive because of its rapid maturation and minimal interference with GFP and GFP-derived markers. Here we evaluate the utility of mRFP1 as a marker in transgenic mice. We show that high level and ubiquitous expression of mRFP1 does not affect mouse development, general physiology, or reproduction. mRFP1 expression can be readily detected with unaided eyes under daylight in transgenic mice on the albino background. The intensity of mRFP1 signals can be used to distinguish homozygous and heterozygous transgenic mice. Together, these features make mRFP1 an attractive marker for broad applications in transgenic research. 相似文献
994.
Understanding the variability of plant WUE and its control mechanism can promote the comprehension to the coupling relationship of water and carbon cycle in terrestrial ecosystem, which is the foundation for developing water-carbon coupling cycle model. In this paper, we made clear the differences of net assimilation rate, transpiration rate, and WUE between the two species by comparing the experiment data of soybean (Glycine max Merr.) and maize (Zea mays L.) plants under water and soil nutrient stresses. WUE of maize was about two and a half times more than that of soybean in the same weather conditions. Enhancement of water stresses led to the marked decrease of Am and Em of two species, but water stresses of some degree could improve WUE, and this effect was more obvious for soybean. WUE of the two species changed with psiL in a second-order curve relation, and the WUE at high fertilization was higher than that at low fertilization, this effect was especially obvious for maize. Moreover, according to the synthetic model of photosynthesis-transpiration based on stomatal behavior (SMPTSB) presented by Yu et al. (2001), the WUE model and its applicability were discussed with the data measured in this experiment. The WUE estimated by means of the model accorded well with the measured values. However, this model underestimated the WUE for maize slightly, thus further improvement on the original model was made in this study. Finally, by discussing some physiological factors controlling Am and WUE, we made clear the physiological explanation for differences of the relative contributions of stomata- and mesophyll processes to control of Am and WUE, and the applicability of WUE model between the two species. Because the requirement to stomatal conductance by unit change of net assimilation rate is different, the responses of opening-closing activity of stomata to environmental stresses are different between the two species. To obtain the same level of net assimilation rate, soybean has to open its stomata more widely to keep small stomatal resistance, as compared with maize. 相似文献
995.
Chang Y Zhuang D Zhang C Hassid A 《American journal of physiology. Heart and circulatory physiology》2004,287(5):H2201-H2208
Migration and proliferation of vascular smooth muscle cells are key events in injury-induced neointima formation. Several growth factors and ANG II are thought to be involved in neointima formation. A recent report indicated that vascular injury is associated with increased mRNA levels of protein tyrosine phosphatase (PTP)-1B (PTP-1B). In the present study, we tested the following hypotheses: 1) rat carotid artery injury induces the expression of PTP-1B, Src homology-2 domain phosphatase (SHP-2), and PTP-proline, glutamate, serine, and threonine sequence (PEST) protein; and 2) polypeptide growth factors as well as ANG II increase the levels of tyrosine phosphatases in cultured rat aortic smooth muscle cells. We found that vascular injury induced by balloon catheter increases the protein levels of aforementioned phosphatases and that these effects occur in a PTP specific, as well as temporally and regionally specific, manner. Moreover, treatment of cultured primary rat aortic smooth muscle cells with PDGF or bFGF, but not with IGF1, EGF, or ANG II, increases PTP-1B, SHP-2, and PTP-PEST protein levels. These results suggest that increased PDGF and bFGF levels, occurring after vascular injury, may induce expression of several PTPs. 相似文献
996.
Schelonka RL Ivanov II Jung DH Ippolito GC Nitschke L Zhuang Y Gartland GL Pelkonen J Alt FW Rajewsky K Schroeder HW 《Journal of immunology (Baltimore, Md. : 1950)》2005,175(10):6624-6632
To test the contribution of individual D gene segments to B cell development and function, we used gene targeting to create mice that contain only DFL16.1 in the DH locus. We term this D-limited IgH allele DeltaD-DFL. Although the absolute number of IgM+IgD- B cells in the bone marrow was decreased, homozygous DeltaD-DFL BALB/c mice contained normal numbers of IgM+IgD+ B cells in bone marrow and spleen and normal numbers of B1a, B1b, and B2 cells in the peritoneal cavity. Bone marrow IgM+IgD+ B cells express a CDR-H3 repertoire similar in length and amino acid composition to the DFL16.1 subset of the wild-type BALB/c repertoire but divergent from sequences that do not contain DFL16.1. This similarity in content is the product of both germline bias and somatic selection, especially in the transition to the mature IgM+IgD+ stage of development. Serum Ig concentrations and the humoral immune response to a T-dependent Ag ([4-hydroxy-3-nitrophenyl]acetyl hapten) were nearly identical to wild-type littermate controls. A greater variance in the immune response to the T-independent Ag (alpha(1-->3)-dextran) was observed in DeltaD-DFL homozygotes, with half of the mice exhibiting levels below the range exhibited by controls. Although limited to a repertoire specific to DFL16.1, the presence of a single DH gene segment of normal sequence was sufficient for development of normal numbers of mature B cells and for robust humoral immune function. 相似文献
997.
Jialei Ji Wenxue Cao Xin Dong Zezhou Liu Zhiyuan Fang Mu Zhuang Yangyong Zhang Honghao Lv Yong Wang Peitian Sun Yumei Liu Zhansheng Li Limei Yang 《Molecular breeding : new strategies in plant improvement》2018,38(11):128
Bright green of leaf head is an important characteristic in cabbage breeding. Wax-less cabbage shows glossy phenotype on leaf surface, which facilitates the brilliant green cabbage breeding. In this study, we identified a spontaneous glossy mutant g21-3 in cabbage. Genetic analyses showed that its glossy phenotype is controlled by a single recessive gene. Further analysis indicated that the glossy phenotype of g21-3 and a known glossy cabbage mutant 10Q-961 was controlled by a same locus. According to the fine-mapping of glossy-controlled gene in 10Q-961, BoCER1 was identified as a candidate gene which was found to be closely related to the glossy phenotype in g21-3. Sub-cellular localization showed that BoCER1 protein is localized to the endoplasmic reticulum. Sequence analysis revealed that a 252-bp insertion was included in the fourth intron of BoCER1 in g21-3, but not in the wild-type 21-3. The insertion significantly inhibited the expression of BoCER1. A marker designed to distinguish between the BoCER1 alleles in g21-3 and wild-type cabbage co-segregated perfectly with glossy/waxy phenotypes in backcross population, confirming that the insertion mutation of BoCER1 is responsible for the glossy phenotype. The allele-specific marker is effective for marker-assisted selection of the glossy cabbage. 相似文献
998.
999.
1000.