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   20297篇
  免费   1661篇
  国内免费   1679篇
  23637篇
  2024年   44篇
  2023年   185篇
  2022年   404篇
  2021年   699篇
  2020年   542篇
  2019年   689篇
  2018年   731篇
  2017年   634篇
  2016年   905篇
  2015年   1258篇
  2014年   1505篇
  2013年   1623篇
  2012年   1913篇
  2011年   1828篇
  2010年   1237篇
  2009年   1033篇
  2008年   1298篇
  2007年   1178篇
  2006年   1005篇
  2005年   949篇
  2004年   838篇
  2003年   774篇
  2002年   646篇
  2001年   305篇
  2000年   255篇
  1999年   216篇
  1998年   185篇
  1997年   140篇
  1996年   96篇
  1995年   77篇
  1994年   58篇
  1993年   47篇
  1992年   50篇
  1991年   45篇
  1990年   24篇
  1989年   32篇
  1988年   28篇
  1987年   10篇
  1986年   12篇
  1985年   18篇
  1984年   15篇
  1983年   10篇
  1982年   13篇
  1981年   8篇
  1979年   8篇
  1976年   6篇
  1972年   7篇
  1970年   6篇
  1969年   6篇
  1967年   6篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
41.
Multiple sclerosis (MS) and neuromyelitis optica (NMO) are demyelinating autoimmune inflammatory diseases that affect the central nervous system (CNS). Previous genome-wide or candidate gene studies have suggested that genetic variants might be associated with the risk of MS or NMO. Aquaporin 4 (AQP4) is a commonly distributed water channel in astrocytes of the CNS, and its expression is decreased in NMO lesions due to astrocyte cytotoxicity. Previous studies have suggested the associations of AQP4 single nucleotide polymorphisms (SNPs) with MS and/or NMO. However, there have been few replication studies in various ethnic populations. This study, as the first of its kind performed in an Asian population, investigated associations of AQP4 SNPs with the risk of inflammatory demyelinating disease (IDD), including MS and NMO, in a Korean population. A total of seven common AQP4 SNPs were selected based on status of linkage disequilibrium (LD), and then genotyped in 178 IDD cases (79 MS and 99 NMO patients) and 237 normal controls. Statistical analyses showed no significant associations between AQP4 SNPs/haplotypes and development of IDD, including MS and NMO (P > 0.05). Further replications in larger cohorts and other ethnic groups are needed.  相似文献   
42.
The incidence of lung cancer is increasing worldwide. Although great progress in lung cancer treatment has been made, the clinical outcome is still unsatisfactory. Tripartite motif (TRIM)-containing proteins has been shown to be closely related to tumor progression. However, the function of TRIM46 in lung cancer is largely unknown. Here, TRIM46 amplification was found in lung adenocarcinoma (LUAD) tissues and TRIM46 amplification was significantly associated with a poor survival rate. Overexpression of wild type TRIM46 increased the proliferation of LUAD cells and glycolysis, promoted xenografts growth, and enhanced cisplatin (DDP) resistance of LUAD cells via increased ubiquitination of pleckstrin homology domain leucine-rich repeat protein phosphatase 2 (PHLPP2) and upregulation of p-AKT. In contrast, overexpression of RING-mutant TRIM46 did not show any effects, suggesting the function of TRIM46 was dependent on the E3 ligase activity. Furthermore, we found that TRIM46 promoted LUAD cell proliferation and DDP resistance by enhancing glycolysis. PHLPP2 overexpression reversed the effects of TRIM46 overexpression. Amplification of TRIM46 also promoted LUAD growth and enhanced its DDP resistance in a patient-derived xenograft (PDX) model. In conclusion, our data highlight the importance of TRIM46/PHLPP2/AKT signaling in lung cancer and provide new insights into therapeutic strategies for lung cancer.Subject terms: Cancer, Biomarkers  相似文献   
43.
44.
Triptolide is a diterpenoid triepoxide derived from the traditional Chinese medical herb Tripterygium wilfordii. In the present study, we demonstrated that this phytochemical attenuated colon cancer growth in vitro and in vivo. Using a proteomic approach, we found that 14‐3‐3 epsilon, a cell cycle‐ and apoptosis‐related protein, was altered in colon cancer cells treated with triptolide. In this regard, triptolide induced cleavage and perinuclear translocation of 14‐3‐3 epsilon. Taken together, our findings suggest that triptolide may merit investigation as a potential therapeutic agent for colon cancer, and its anticancer action may be associated with alteration of 14‐3‐3 epsilon. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   
45.
Alignment of molecular networks by integer quadratic programming   总被引:3,自引:0,他引:3  
MOTIVATION: With more and more data on molecular networks (e.g. protein interaction networks, gene regulatory networks and metabolic networks) available, the discovery of conserved patterns or signaling pathways by comparing various kinds of networks among different species or within a species becomes an increasingly important problem. However, most of the conventional approaches either restrict comparative analysis to special structures, such as pathways, or adopt heuristic algorithms due to computational burden. RESULTS: In this article, to find the conserved substructures, we develop an efficient algorithm for aligning molecular networks based on both molecule similarity and architecture similarity, by using integer quadratic programming (IQP). Such an IQP can be relaxed into the corresponding quadratic programming (QP) which almost always ensures an integer solution, thereby making molecular network alignment tractable without any approximation. The proposed framework is very flexible and can be applied to many kinds of molecular networks including weighted and unweighted, directed and undirected networks with or without loops. AVAILABILITY: Matlab code and data are available from http://zhangroup.aporc.org/bioinfo/MNAligner or http://intelligent.eic.osaka-sandai.ac.jp/chenen/software/MNAligner, or upon request from authors. SUPPLEMENTARY INFORMATION: Supplementary data are available at Bioinformatics online.  相似文献   
46.
47.
Various physiological and psychological functions are influenced by circadian typology (CT), which was reported to be related to resilience. However, few studies have assessed the effects of CT in relation to resilience. The aim of the present study was to assess the influence of CT on sleep-related symptoms, physical fatigue and psychological well-being in relation to resilience. The present study included a total of 1794 healthy hospital employees, and they completed the Morningness–Eveningness Questionnaire, Connor–Davidson Resilience Scale, Pittsburgh Sleep Quality Index, Epworth Sleepiness Scale, Fatigue Severity Scale, Hospital Anxiety and Depression Scale and World Health Organization Quality of Life Scale Abbreviated Version. Subjects with evening type showed lower sleep quality, more daytime sleepiness and physical fatigue than neither types and morning types. Additionally, evening types were more depressed and anxious and reported a poorer quality of life. CT was found to be a significant predictor of sleep quality, but CT was minimally associated with physical fatigue and psychological well-being in the regression analysis. Instead, resilience was substantially related to all of the variables measured. In conclusion, CT independently predicts sleep quality, but the effects of CT on physical fatigue and psychological well-being are negligible compared to those of resilience.  相似文献   
48.
Our previous study confirmed the ability of Lactobacillus plantarum CCFM8610 to protect against acute cadmium (Cd) toxicity in mice. This study was designed to evaluate the protective effects of CCFM8610 against chronic Cd toxicity in mice and to gain insights into the protection mode of this strain. Experimental mice were divided into two groups and exposed to Cd for 8 weeks via drinking water or intraperitoneal injection. Both groups were further divided into four subgroups, control, Cd only, CCFM8610 only, and Cd plus CCFM8610. Levels of Cd were measured in the feces, liver, and kidneys, and alterations of several biomarkers of Cd toxicity were noted. The results showed that when Cd was introduced orally, cotreatment with Cd and CCFM8610 effectively decreased intestinal Cd absorption, reduced Cd accumulation in tissue, alleviated tissue oxidative stress, reversed hepatic and renal damage, and ameliorated the corresponding histopathological changes. When Cd was introduced intraperitoneally, administration of CCFM8610 did not have an impact on tissue Cd accumulation or reverse the activities of antioxidant enzymes. However, CCFM8610 still offered protection against oxidative stress and reversed the alterations of Cd toxicity biomarkers and tissue histopathology. These results suggest that CCFM8610 is effective against chronic cadmium toxicity in mice. Besides intestinal Cd sequestration, CCFM8610 treatment offers direct protection against Cd-induced oxidative stress. We also provide evidence that the latter is unlikely to be mediated via protection against Cd-induced alteration of antioxidant enzyme activities.  相似文献   
49.
Bacteria were isolated from the mycelial surface of Pleurotus ostreatus and their role in fruiting body induction (fructification) of the edible mushroom P. ostreatus was investigated. Analysis of the bacterial community that colonized the mycelium showed that the species composition and numbers of culturable bacteria differed according to the developmental stage of P. ostreatus. In particular, the population size of fluorescent pseudomonads increased during fruiting body induction. An experiment showed that inoculation of pure cultures of the mycelium with strains of fluorescent Pseudomonas spp. isolated from the mycelial plane of commercially produced mushrooms promoted the formation of primordia and enhanced the development of the basidiome of P. ostreatus. Results of this research strongly suggest that inoculation of the mycelium with specific bacteria may have beneficial applications for mushroom production.  相似文献   
50.
Ooi CH  Oh HK  Wang HZ  Tan AL  Wu J  Lee M  Rha SY  Chung HC  Virshup DM  Tan P 《PLoS genetics》2011,7(12):e1002415
MicroRNAs (miRNAs) are important components of cellular signaling pathways, acting either as pathway regulators or pathway targets. Currently, only a limited number of miRNAs have been functionally linked to specific signaling pathways. Here, we explored if gene expression signatures could be used to represent miRNA activities and integrated with genomic signatures of oncogenic pathway activity to identify connections between miRNAs and oncogenic pathways on a high-throughput, genome-wide scale. Mapping >300 gene expression signatures to >700 primary tumor profiles, we constructed a genome-wide miRNA-pathway network predicting the associations of 276 human miRNAs to 26 oncogenic pathways. The miRNA-pathway network confirmed a host of previously reported miRNA/pathway associations and uncovered several novel associations that were subsequently experimentally validated. Globally, the miRNA-pathway network demonstrates a small-world, but not scale-free, organization characterized by multiple distinct, tightly knit modules each exhibiting a high density of connections. However, unlike genetic or metabolic networks typified by only a few highly connected nodes ("hubs"), most nodes in the miRNA-pathway network are highly connected. Sequence-based computational analysis confirmed that highly-interconnected miRNAs are likely to be regulated by common pathways to target similar sets of downstream genes, suggesting a pervasive and high level of functional redundancy among coexpressed miRNAs. We conclude that gene expression signatures can be used as surrogates of miRNA activity. Our strategy facilitates the task of discovering novel miRNA-pathway connections, since gene expression data for multiple normal and disease conditions are abundantly available.  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