全文获取类型
收费全文 | 30490篇 |
免费 | 2389篇 |
国内免费 | 2097篇 |
专业分类
34976篇 |
出版年
2024年 | 72篇 |
2023年 | 444篇 |
2022年 | 1029篇 |
2021年 | 1713篇 |
2020年 | 1049篇 |
2019年 | 1350篇 |
2018年 | 1289篇 |
2017年 | 938篇 |
2016年 | 1279篇 |
2015年 | 1868篇 |
2014年 | 2219篇 |
2013年 | 2482篇 |
2012年 | 2776篇 |
2011年 | 2468篇 |
2010年 | 1486篇 |
2009年 | 1282篇 |
2008年 | 1509篇 |
2007年 | 1313篇 |
2006年 | 1160篇 |
2005年 | 947篇 |
2004年 | 791篇 |
2003年 | 665篇 |
2002年 | 598篇 |
2001年 | 538篇 |
2000年 | 471篇 |
1999年 | 485篇 |
1998年 | 270篇 |
1997年 | 292篇 |
1996年 | 292篇 |
1995年 | 282篇 |
1994年 | 253篇 |
1993年 | 179篇 |
1992年 | 277篇 |
1991年 | 186篇 |
1990年 | 152篇 |
1989年 | 151篇 |
1988年 | 92篇 |
1987年 | 86篇 |
1986年 | 60篇 |
1985年 | 68篇 |
1984年 | 29篇 |
1983年 | 32篇 |
1982年 | 18篇 |
1981年 | 15篇 |
1980年 | 12篇 |
1979年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
Zinc finger protein5 is required for the control of trichome initiation by acting upstream of zinc finger protein8 in Arabidopsis 总被引:4,自引:0,他引:4
Arabidopsis (Arabidopsis thaliana) trichome development is a model system for studying cell development, cell differentiation, and the cell cycle. Our previous studies have shown that the GLABROUS INFLORESCENCE STEMS (GIS) family genes, GIS, GIS2, and ZINC FINGER PROTEIN8 (ZFP8), control shoot maturation and epidermal cell fate by integrating gibberellins (GAs) and cytokinin signaling in Arabidopsis. Here, we show that a new C2H2 zinc finger protein, ZFP5, plays an important role in controlling trichome cell development through GA signaling. Overexpression of ZFP5 results in the formation of ectopic trichomes on carpels and other inflorescence organs. zfp5 loss-of-function mutants exhibit a reduced number of trichomes on sepals, cauline leaves, paraclades, and main inflorescence stems in comparison with wild-type plants. More importantly, it is found that ZFP5 mediates the regulation of trichome initiation by GAs. These results are consistent with ZFP5 expression patterns and the regional influence of GA on trichome initiation. The molecular analyses suggest that ZFP5 functions upstream of GIS, GIS2, ZFP8, and the key trichome initiation regulators GLABROUS1 (GL1) and GL3. Using a steroid-inducible activation of ZFP5 and chromatin immunoprecipitation experiments, we further demonstrate that ZFP8 is the direct target of ZFP5 in controlling epidermal cell differentiation. 相似文献
992.
Sung K Dolcos S Flor-Henry S Zhou C Gasior C Argo J Dolcos F 《Journal of visualized experiments : JoVE》2011,(53):e2379
The ability to gauge social interactions is crucial in the assessment of others' intentions. Factors such as facial expressions and body language affect our decisions in personal and professional life alike (1). These "friend or foe" judgements are often based on first impressions, which in turn may affect our decisions to "approach or avoid". Previous studies investigating the neural correlates of social cognition tended to use static facial stimuli (2). Here, we illustrate an experimental design in which whole-body animated characters were used in conjunction with functional magnetic resonance imaging (fMRI) recordings. Fifteen participants were presented with short movie-clips of guest-host interactions in a business setting, while fMRI data were recorded; at the end of each movie, participants also provided ratings of the host behaviour. This design mimics more closely real-life situations, and hence may contribute to better understanding of the neural mechanisms of social interactions in healthy behaviour, and to gaining insight into possible causes of deficits in social behaviour in such clinical conditions as social anxiety and autism (3). 相似文献
993.
The population and community characteristics in the Platycladus orientalis forest on Qianfo Mountain in Jinan are studied. The specific composition, spatial pattern, biological spectrum and main species dispersions are reported. It is found that all the main species dispersions are aggregated. The diversity of Shannon-Wiener and Simpson indexes are markedly not correlated with the habitat factors. The patch indexes and niche breadths of the main species have been analysed on such axes as light, soil water and soil organic matter. The value of niche overlap between every two species is high on soil resource axis. 相似文献
994.
A mAb of the IgG1/kappa isotype was raised against human myelin basic protein (MBP) peptide acetyl 1-9. This mAb, termed F23, reacted with human MBP and human MBP peptides acetyl 1-9, 1-14, and 1-44, but not with MBP peptides 10-19, 80-89, or 45-89. According to the guidelines of the molecular recognition theory, a complementary peptide to human MBP peptide 1-9 was synthesized and used to raise murine mAb with anti-Id activity. Two mAb anti-Id, F25F7 and F25C8, both of the IgM/kappa isotype, were selected for further study. These anti-Id reacted with F23, the mAb for which they were selected, and also reacted with another mAb, which was of the IgG1/kappa isotype and was raised to human MBP peptide 80-89. There was no reaction with another control mAb of the IgG1/kappa isotype or murine myeloma IgG1. By immunoblotting techniques, it was demonstrated that the Id on each of the mAbs to MBP peptides was located on the kappa L chain but also could be recognized in nonreduced IgG. The cross-reactive anti-Id suppressed antibody secretion of Id-producing hybridoma cells in an Id-specific manner, and kinetic studies suggest an intracellular mechanism for the suppression. These cross-reactive Id among antibodies to different MBP peptides imply that the same V region genes of kappa L chains are involved in the selection of antibodies to an autoantigen, like MBP, and may play a role in the modulation of immune responses against MBP in certain inflammatory demyelinating diseases. 相似文献
995.
996.
Sheila Ommeh Wei Zhang Ali Zohaib Jing Chen Huajun Zhang Ben Hu Xing-Yi Ge Xing-Lou Yang Moses Masika Vincent Obanda Yun Luo Shan Li Cecilia Waruhiu Bei Li Yan Zhu Desterio Ouma Vincent Odendo Lin-Fa Wang Danielle E. Anderson Jacqueline Lichoti Erick Mungube Francis Gakuya Peng Zhou Kisa-Juma Ngeiywa Bing Yan Bernard Agwanda Zheng-Li Shi 《中国病毒学》2019,34(1):115-115
997.
Xiaobo Zhou Yamin Rao Qilin Sun Yang Liu Jun Chen Wenbo Bu 《Journal of cellular physiology》2019,234(12):22017-22027
Long noncoding RNA CPS1-IT1 is recently recognized as a tumor suppressor in several cancers. Here, we investigate the role of CPS1-IT1 in human melanoma. Presently, our study reveals the low expression of CPS1-IT1 in human melanoma tissues and cell lines, which is significantly associated with metastasis and tumor stage. Besides, the potential of CPS1-IT1 as a prognosis-predictor is strongly indicated. Functionally, CPS1-IT1 overexpression inhibits cell migration, invasion, epithelial–mesenchymal transition, and angiogenesis in melanoma cells. CYR61, an angiogenic factor that participates in tumor metastasis as well as a recognized oncogene in melanoma, is shown to be confined under CPS1-IT1 overexpression in melanoma cells. Furthermore, enforced expression of Cyr61 in CPS1-IT1-silenced melanoma cells dramatically normalized the protein level of Cyr61 and that of its downstream targets vascular endothelial growth factor and matrix metalloproteinase-9, as well as the repressive effect of CPS1-IT1 overexpression on melanoma cell metastasis. BRG1, a core component of SWI/SNF complex, is implied to interact with both CPS1-IT1 and Cyr61 in melanoma cells. Moreover, CPS1-IT1 negatively regulates Cyr61 expression by blocking the binding of BRG1 to Cyr61 promoter. Jointly, CPS1-IT1 controls melanoma metastasis through impairing Cyr61 expression via competitively binding with BRG1, uncovering a novel potential therapeutic and prognostic biomarker for patients with melanoma. 相似文献
998.
Yin Hu Wei Chen Tianyu Lei Bin Zhou Yu Jiao Yichao Yan Xinchuan Du Jianwen Huang Chunyang Wu Xuepeng Wang Yang Wang Bo Chen Jun Xu Chao Wang Jie Xiong 《Liver Transplantation》2019,9(7)
Significant progress has achieved for developing lithium–sulfur (Li–S) batteries with high specific capacities and excellent cyclic stability. However, some critical issues emerge when attempts are made to raise the areal sulfur loading and increase the operation current density to meet the standards for various industrial applications. In this work, polyethylenimine‐functionalized carbon dots (PEI‐CDots) are designed and prepared for enhancing performance of the Li–S batteries with high sulfur loadings and operation under high current density situations. Strong chemical binding effects towards polysulfides and fast ion transport property are achieved in the PEI‐CDots‐modified cathodes. At a high current density of 8 mA cm?2, the PEI‐CDots‐modified Li–S battery delivers a reversible areal capacity of 3.3 mAh cm?2 with only 0.07% capacity decay per cycle over 400 cycles at 6.6 mg sulfur loading. Detailed analysis, involving electrochemical impedance spectroscopy, cyclic voltammetry, and density functional theory calculations, is done for the elucidation of the underlying enhancement mechanism by the PEI‐CDots. The strongly localized sulfur species and the promoted Li+ ion conductivity at the cathode–electrolyte interface are revealed to enable high‐performance Li–S batteries with high sulfur loading and large operational current. 相似文献
999.
1000.
Yun Ren Dan Chen Wenjie Li Dan Zhou Tao Luo Guoqiang Yuan Jing Zeng Ye Cao Zhongshan He Ting Zou Qiming Deng Shiquan Wang Aiping Zheng Jun Zhu Yueyang Liang Huainian Liu Lingxia Wang Ping Li Shuangcheng Li 《The Plant journal : for cell and molecular biology》2019,98(2):315-328
Meiosis is essential for eukaryotic sexual reproduction and plant fertility, and crossovers (COs) are essential for meiosis and the formation of new allelic combinations in gametes. In this study, we report the isolation of a meiotic gene, OsSHOC1, and the identification of its partner, OsPTD1. Osshoc1 was sterile both in male and female gametophytes, and it showed a striking reduction in the number of meiotic COs, indicating that OsSHOC1 was required for normal CO formation. Further investigations showed that OsSHOC1 physically interacted with OsPTD1 and that the latter was also required for normal CO formation and plant fertility. Additionally, the expression profiles of both genes were consistent with their functions. Our results suggest that OsSHOC1 and OsPTD1 are essential for rice fertility and CO formation, possibly by stabilizing the recombinant intermediates during meiosis. 相似文献