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   7617篇
  免费   543篇
  国内免费   705篇
  8865篇
  2024年   25篇
  2023年   99篇
  2022年   257篇
  2021年   409篇
  2020年   301篇
  2019年   347篇
  2018年   323篇
  2017年   265篇
  2016年   358篇
  2015年   498篇
  2014年   562篇
  2013年   612篇
  2012年   762篇
  2011年   642篇
  2010年   362篇
  2009年   365篇
  2008年   387篇
  2007年   328篇
  2006年   288篇
  2005年   238篇
  2004年   206篇
  2003年   175篇
  2002年   152篇
  2001年   151篇
  2000年   116篇
  1999年   100篇
  1998年   67篇
  1997年   71篇
  1996年   70篇
  1995年   54篇
  1994年   49篇
  1993年   31篇
  1992年   41篇
  1991年   20篇
  1990年   25篇
  1989年   19篇
  1988年   16篇
  1987年   16篇
  1986年   11篇
  1985年   18篇
  1984年   9篇
  1983年   6篇
  1982年   5篇
  1981年   3篇
  1980年   2篇
  1979年   1篇
  1966年   1篇
  1965年   2篇
排序方式: 共有8865条查询结果,搜索用时 179 毫秒
1.
Dear Editor, Sex determination is one of the most fundamental develop-ment processes,as gender is the first and most important identity of human.In most mammals...  相似文献   
2.
3.
Xie C  Yao MZ  Liu JB  Xiong LK 《Cytokine》2011,56(3):550-559
Inflammation may play a major role in the pathogenesis of preeclampsia (PE). In this meta-analysis, we determined whether maternal polymorphisms and serum concentrations of tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), and interleukin-10 (IL-10) were associated with PE. All studies investigating the associations between PE and maternal polymorphisms of TNF-α-308G/A, IL-6-174G/C, and IL-10-1082A/G or serum concentrations of TNF-α, IL-6, and IL-10 were reviewed. We found that neither maternal TNF-α-308G/A (p=0.86, odds ratio [OR]=0.98, 95% confidence interval [CI], 0.76-1.25), IL-6 174G/C (p=0.14, OR=1.23, 95% CI, 0.93-1.61), nor IL-10-1082A/G (p=0.72, OR=1.07, 95% CI, 0.75-1.52) were associated with PE. On the other hand, maternal TNF-α (p<0.00001, weighted mean difference [WMD]=19.63 pg/ml, 95% CI, 18.54-20.72 pg/ml), IL-6 (p<0.00001, WMD=6.58 pg/ml, 95% CI, 5.49-7.67 pg/ml), and IL-10 (p=0.0005, WMD=19.30 pg/ml, 95% CI, 8.42-30.17 pg/ml) concentrations were significantly higher in PE patients versus controls. Our findings strengthen the clinical evidence that PE is accompanied by exaggerated inflammatory responses, but do not support TNF-α-308G/A, IL-6-174G/C, and IL-10-1082A/G as candidate susceptibility loci in PE.  相似文献   
4.
5.
Functional nanomaterials are playing a crucial role in the emerging field of energy‐related devices. Recently, as a novel synthesis method, high‐temperature shock (HTS), which is rapid, low cost, eco‐friendly, universal, scalable, and controllable, has provided a promising option for the rational design and synthesis of various high‐quality nanomaterials. In this report, the HTS technique, including the equipment setup and operating principle, is systematically introduced, and recent progress in the synthesis of nanomaterials for energy storage and conversion applications using this HTS method is summarized. The growth mechanisms of nanoparticles and carbonaceous nanomaterials are thoroughly discussed, followed by the summary of the characteristic advantages of the HTS strategy. A series of nanomaterials prepared by the HTS method, including carbon‐based films, metal nanoparticles and compound nanoparticles, show high performance in the diverse applications of storage energy batteries, highly active catalysts, and smart energy devices. Finally, the future perspectives and directions of HTS in nanomanufacturing for broader applications are presented.  相似文献   
6.
Apoptosis and autophagy mutually regulate various cellular physiological and pathological processes. The crosstalk between autophagy and apoptosis is multifaceted and complicated. Elucidating the molecular mechanism of their crosstalk will advance the therapeutic applications of autophagy for treating cancer and other diseases. NOXA, a BH3-only member of the BCL-2 family, was reported to induce apoptosis and promote autophagy. Here, we report that autophagy regulates apoptosis by targeting NOXA for degradation. Inhibiting autophagy increases NOXA protein levels by extending the protein half-life. NOXA accumulation effectively suppresses tumor cell growth by inducing apoptosis, which is further enhanced when p53 is present. Mechanistically, NOXA is hijacked by p62 as autophagic cargo, and its three lysine residues at the C-terminus are necessary for NOXA degradation in lysosomes. Taken together, our study demonstrates that NOXA serves as a bridge in the crosstalk between autophagy and apoptosis and implies that autophagy inhibitors could be an effective therapy for cancer, especially wild-type p53-containing cancer.  相似文献   
7.
Methionine aminopeptidase (MetAP) catalyzes the removal of methionine from newly synthesized polypeptides. MetAP carries out this cleavage with high precision, and Met is the only natural amino acid residue at the N terminus that is accepted, although type I and type II MetAPs use two different sets of residues to form the hydrophobic S1 site. Characteristics of the S1 binding pocket in type I MetAP were investigated by systematic mutation of each of the seven S1 residues in Escherichia coli MetAP type I (EcMetAP1) and human MetAP type I (HsMetAP1). We found that Tyr-65 and Trp-221 in EcMetAP1, as well as the corresponding residues Phe-197 and Trp-352 in HsMetAP1, were essential for the hydrolysis of a thiopeptolide substrate, Met-S-Gly-Phe. Mutation of Phe-191 to Ala in HsMetAP1 caused inactivity in contrast to the full activity of EcMetAP1(Y62A), which may suggest a subtle difference between the two type I enzymes. The more striking finding is that mutation of Cys-70 in EcMetAP1 or Cys-202 in HsMetAP1 opens up the S1 pocket. The thiopeptolides Leu-S-Gly-Phe and Phe-S-Gly-Phe, with previously unacceptable Leu or Phe as the N-terminal residue, became efficient substrates of EcMetAP1(C70A) and HsMetAP1(C202A). The relaxed specificity shown in these S1 site mutants for the N-terminal residues was confirmed by hydrolysis of peptide substrates and inhibition by reaction products. The structural features at the enzyme active site will be useful information for designing specific MetAP inhibitors for therapeutic applications.  相似文献   
8.
9.
10.
Recent publications have found an association between variants of exostosin 2 (EXT2) gene and the risk of type 2 diabetes in some population but not in others. In an attempt to address these inconsistencies, we investigated EXT2 variants in two independent cohorts, and conducted a literature-based meta-analysis. Through regression model, we assessed the relationship between the EXT2 single nucleotide polymorphisms (SNPs) (rs3740878, rs11037909 and rs1113132) and the risk of type 2 diabetes in Han Chinese population, including a total of 2,533 cases and 2,643 controls. We combined our data with that from previously published studies and performed a meta-analysis to evaluate the effect size of the gene. Consistent with some studies, we found marginal association for the rs3740878 (OR = 1.07, 95 % CI = 0.99, 1.16, p = 0.09), rs11037909 (OR = 1.07, 95 % CI = 0.99, 1.16, p = 0.08), and rs1113132 (OR = 1.08, 95 % CI = 1.00, 1.17, p = 0.06) in our 2 cohorts. Meta-analysis, comprising 9,224 type 2 diabetes and 10,484 controls, revealed that three SNPs (rs3740878, rs11037909 and rs1113132) in EXT2 were significantly associated with type 2 diabetes (ORs range from 1.06 to 1.07, p = 0.038, p = 0.008 and p = 0.005, respectively). Variation in the EXT2 locus appears to be associated with a small increase in the risk of type 2 diabetes. However, well-designed prospective studies with larger sample size and more ethnic groups are needed to further validate the results.  相似文献   
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