首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   42018篇
  免费   3777篇
  国内免费   5682篇
  2024年   93篇
  2023年   531篇
  2022年   1267篇
  2021年   2255篇
  2020年   1586篇
  2019年   2032篇
  2018年   1835篇
  2017年   1448篇
  2016年   1937篇
  2015年   2794篇
  2014年   3388篇
  2013年   3469篇
  2012年   4210篇
  2011年   3781篇
  2010年   2414篇
  2009年   2204篇
  2008年   2457篇
  2007年   2163篇
  2006年   1918篇
  2005年   1547篇
  2004年   1314篇
  2003年   1234篇
  2002年   997篇
  2001年   681篇
  2000年   598篇
  1999年   576篇
  1998年   366篇
  1997年   327篇
  1996年   310篇
  1995年   249篇
  1994年   239篇
  1993年   152篇
  1992年   194篇
  1991年   147篇
  1990年   118篇
  1989年   98篇
  1988年   85篇
  1987年   68篇
  1986年   67篇
  1985年   90篇
  1984年   31篇
  1983年   33篇
  1982年   31篇
  1981年   26篇
  1980年   11篇
  1979年   22篇
  1978年   9篇
  1974年   8篇
  1973年   11篇
  1971年   8篇
排序方式: 共有10000条查询结果,搜索用时 199 毫秒
991.
Colorectal cancer is one of the most common and leading malignancies globally. Long noncoding RNAs (lncRNAs) function as potentially critical regulator in colorectal cancer. LINC01234, a novel lncRNA in tumor biology, regulates the progression of various tumors. However, the tumorigenic mechanism of LINC01234 in colorectal cancer is still unclear. This study was performed with the aim to prospectively investigate clinical significance, effect, and mechanism of lncRNA LINC01234 in colorectal cancer. First, we found that LINC01234, localized in the cytoplasm, was increased in both colorectal cancer cell lines and tissues. Subsequent functional assays suggested LINC01234 knockdown suppressed cell proliferation, migration, and invasion of colorectal cancer cells, while blocked cell cycle and induced cell apoptosis. Moreover, we identified that miR-1284 was target of LINC01234, we further demonstrated a negative correlation with LINC01234 in colorectal cancer tissues and cells. Furthermore, miR-1284 targeted and suppressed tumor necrosis factor receptor–associated factor 6 (TRAF6). Loss-of-function assay revealed that LINC01234 silencing suppressed colorectal cancer progression through inhibition of miR-1284. In vivo subcutaneous xenotransplanted tumor model indicated LINC01234 knockdown inhibited in vivo tumorigenic ability of colorectal cancer via downregulation of TRAF6. Collectively, this study clarified the biological significance of LINC01234/miR-1284/TRAF6 axis in colorectal cancer progression, providing insights into LINC01234 as novel potential therapeutic target for colorectal cancer therapeutic from bench to clinic.  相似文献   
992.
Ming  Nan  Ma  Nana  Jiao  Baozhen  Lv  Wei  Meng  Qingwei 《Plant Molecular Biology Reporter》2020,38(1):75-94

In plants, C2H2-type zinc finger proteins play important roles in multiple processes, including plant growth and development, as well as biotic and abiotic responses. In the present study, based on the presence of the C2H2 domain (CX2~4CX3FX5LX2HX3~5H), 112 C2H2-type zinc finger proteins were predicted in tomato. Through gene and protein structures analyses and phylogenetic analysis, the 112 C2H2-type zinc finger proteins were divided into five subfamilies. Members of the same subfamily shared similarities in gene and protein structures, while members of different subfamilies contained different numbers of the C2H2 domain. The tissue expression pattern analysis showed that 24 C2H2-type zinc finger proteins are constitutively expressed in all tissues, indicating that they may play important roles in the growth and development of all tissues. In addition, under chilling (4 °C), heat (42 °C), high salinity (200 Mm NaCl), and osmotic (20% PEG) stresses, members of C2H2-type zinc finger family were induced to varying degrees, which suggested that these genes were involved in multiple abiotic stress responses. This study will provide theoretical basis for further research of C2H2-type zinc finger proteins in tomato.

  相似文献   
993.
994.
Designing protein sequences that fold to a given three-dimensional (3D) structure has long been a challenging problem in computational structural biology with significant theoretical and practical implications. In this study, we first formulated this problem as predicting the residue type given the 3D structural environment around the C α atom of a residue, which is repeated for each residue of a protein. We designed a nine-layer 3D deep convolutional neural network (CNN) that takes as input a gridded box with the atomic coordinates and types around a residue. Several CNN layers were designed to capture structure information at different scales, such as bond lengths, bond angles, torsion angles, and secondary structures. Trained on a very large number of protein structures, the method, called ProDCoNN (protein design with CNN), achieved state-of-the-art performance when tested on large numbers of test proteins and benchmark datasets.  相似文献   
995.
Many computational methods have been developed to discern intratumor heterogeneity (ITH) using DNA sequence data from bulk tumor samples. These methods share an assumption that two mutations arise from the same subclone if they have similar mutant allele-frequencies (MAFs), and thus it is difficult or impossible to distinguish two subclones with similar MAFs. Single-cell DNA sequencing (scDNA-seq) data can be very informative for ITH inference. However, due to the difficulty of DNA amplification, scDNA-seq data are often very noisy. A promising new study design is to collect both bulk and single-cell DNA-seq data and jointly analyze them to mitigate the limitations of each data type. To address the analytic challenges of this new study design, we propose a computational method named BaSiC (B ulk tumor a nd Si ngle C ell), to discern ITH by jointly analyzing DNA-seq data from bulk tumor and single cells. We demonstrate that BaSiC has comparable or better performance than the methods using either data type. We further evaluate BaSiC using bulk tumor and single-cell DNA-seq data from a breast cancer patient and several leukemia patients.  相似文献   
996.
997.
Interference occurs between individuals when the treatment (or exposure) of one individual affects the outcome of another individual. Previous work on causal inference methods in the presence of interference has focused on the setting where it is a priori assumed that there is “partial interference,” in the sense that individuals can be partitioned into groups wherein there is no interference between individuals in different groups. Bowers et al. (2012, Political Anal, 21, 97–124) and Bowers et al. (2016, Political Anal, 24, 395–403) consider randomization-based inferential methods that allow for more general interference structures in the context of randomized experiments. In this paper, extensions of Bowers et al. that allow for failure time outcomes subject to right censoring are proposed. Permitting right-censored outcomes is challenging because standard randomization-based tests of the null hypothesis of no treatment effect assume that whether an individual is censored does not depend on treatment. The proposed extension of Bowers et al. to allow for censoring entails adapting the method of Wang et al. (2010, Biostatistics, 11, 676–692) for two-sample survival comparisons in the presence of unequal censoring. The methods are examined via simulation studies and utilized to assess the effects of cholera vaccination in an individually randomized trial of 73 000 children and women in Matlab, Bangladesh.  相似文献   
998.
Protein lipoylation is essential for the function of many key enzymes but barely studied kinetically. Here, the two-step reaction cascade of H protein lipoylation catalyzed by the multifunctional enzyme lipoate–protein ligase A (LplA) was quantitatively and differentially studied. We discovered new phenomena and unusual kinetics of the cascade: (a) the speed of the first reaction is faster than the second one by two orders of magnitude, leading to high accumulation of the intermediate lipoyl-AMP (Lip-AMP); (b) Lip-AMP is hydrolyzed, but only significantly at the presence of H protein and in competition with the lipoylation; (c) both the lipoylation of H protein and its hydrolysis is enhanced by the apo and lipoylated forms of H protein and a mutant without the lipoylation site. A conceptual mechanistic model is proposed to explain these experimental observations in which conformational change of LplA upon interaction with H protein and competitive nucleophilic attacks play key roles.  相似文献   
999.
1000.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号