全文获取类型
收费全文 | 4968篇 |
免费 | 399篇 |
国内免费 | 459篇 |
专业分类
5826篇 |
出版年
2024年 | 14篇 |
2023年 | 72篇 |
2022年 | 165篇 |
2021年 | 236篇 |
2020年 | 164篇 |
2019年 | 262篇 |
2018年 | 221篇 |
2017年 | 165篇 |
2016年 | 201篇 |
2015年 | 328篇 |
2014年 | 378篇 |
2013年 | 383篇 |
2012年 | 464篇 |
2011年 | 479篇 |
2010年 | 258篇 |
2009年 | 205篇 |
2008年 | 236篇 |
2007年 | 227篇 |
2006年 | 206篇 |
2005年 | 186篇 |
2004年 | 152篇 |
2003年 | 125篇 |
2002年 | 103篇 |
2001年 | 79篇 |
2000年 | 44篇 |
1999年 | 58篇 |
1998年 | 44篇 |
1997年 | 50篇 |
1996年 | 47篇 |
1995年 | 32篇 |
1994年 | 38篇 |
1993年 | 20篇 |
1992年 | 32篇 |
1991年 | 24篇 |
1990年 | 19篇 |
1989年 | 12篇 |
1988年 | 11篇 |
1987年 | 14篇 |
1986年 | 8篇 |
1985年 | 21篇 |
1982年 | 2篇 |
1980年 | 2篇 |
1976年 | 4篇 |
1975年 | 3篇 |
1974年 | 3篇 |
1973年 | 4篇 |
1972年 | 6篇 |
1971年 | 5篇 |
1970年 | 2篇 |
1967年 | 2篇 |
排序方式: 共有5826条查询结果,搜索用时 0 毫秒
41.
ISB recommendation on definitions of joint coordinate systems of various joints for the reporting of human joint motion--Part II: shoulder, elbow, wrist and hand 总被引:14,自引:0,他引:14
Wu G van der Helm FC Veeger HE Makhsous M Van Roy P Anglin C Nagels J Karduna AR McQuade K Wang X Werner FW Buchholz B;International Society of Biomechanics 《Journal of biomechanics》2005,38(5):981-992
In this communication, the Standardization and Terminology Committee (STC) of the International Society of Biomechanics proposes a definition of a joint coordinate system (JCS) for the shoulder, elbow, wrist, and hand. For each joint, a standard for the local axis system in each articulating segment or bone is generated. These axes then standardize the JCS. The STC is publishing these recommendations so as to encourage their use, to stimulate feedback and discussion, and to facilitate further revisions. Adopting these standards will lead to better communication among researchers and clinicians. 相似文献
42.
人新基因hbrp的染色体定位及其对TPK活性的抑制作用(简报) 总被引:1,自引:0,他引:1
hbrp(Human BSP-Related Protein)是我们实验室最近在睾丸组织中克隆的一个人与BSP(bovine seminal plasma)蛋白相关的新基因。为了将有关该新基因信息与现有人类基因组转录图相整合,我们应用荧光原位杂交(fluorescent in situ hybridizationFISH)法进行了该基因的人染色体基因定位,结果成功地将hbrp基因定位在人19号染色体长臂1区3带上。hbrp基因是在对BSP蛋白功能的研究过程中发现并克隆的,其同源性分析发现,与其序列最相近 相似文献
43.
基因重复是普遍存在的生物学现象, 是基因组和遗传系统多样化的重要推动力量, 在生物进化过程中发挥着极其重要的作用。基因重复有何利弊, 基因发生重复后, 2个重复子拷贝的保留在基因功能方面是否存在偏好性, 子拷贝在表达和进化速率上如何分化, 以及重复基因为什么会被保留下来一直是进化生物学领域研究的热点问题之一。该文对以上重复基因研究的热点问题进行了介绍, 并对重复基因的进化机制和理论模型及其近年来的一些主要研究进展进行了综述。 相似文献
44.
Jiwen Wang Jinyu Wei Xiaoling Xu Wenting Pan Yunxia Ge Changchun Zhou Chao Liu Jia Gao Ming Yang Weimin Mao 《PloS one》2014,9(4)
China was one of the countries with highest esophageal squamous cell carcinoma (ESCC) incidence and mortality worldwide. Alcohol drinking has been identified as a major environmental risk-factor related to ESCC. The alcohol dehydrogenase (ADH) family are major enzymes involved in the alcohol-metabolizing pathways, including alcohol dehydrogenase 1B (ADH1B) and ADH1C. Interestingly, ADH1B and ADH1C genes locate tandemly with ADH7 in a genomic segment as a gene cluster, and are all polymorphic. Several ESCC susceptibility single nucleotide polymorphisms (SNPs) of the ADH1B-ADH1C-ADH7 cluster have been identified previously through a genome-wide association study (GWAS). In the study, we examined the association between five ADH1B-ADH1C-ADH7 cluster SNPs (rs1042026, rs17033, rs1614972, rs1789903 and rs17028973) and risk of developing ESCC. Genotypes were determined in two independent case-control sets from two regions of China. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated by logistic regression. Our data demonstrated that these ADH1B-ADH1C-ADH7 cluster SNPs confer susceptibility to ESCC in these two case-control sets, which were consistent to results of the previous GWAS. 相似文献
45.
Xiao Han Yun Cui Chuanhua Yang Weili Sun Jianghong Wu Yunjie Gao Hanbing Xue Xiaobo Li Lei Shen Yanshen Peng Hanhui Zhang Yan Hu Liying Zhong Xiaoyu Chen Zhizheng Ge 《PloS one》2014,9(7)
Background
Gastrointestinal neuroendocrine neoplasms (GI-NENs) are often located in the deep mucosa or submucosa, and the efficacy of endoscopic biopsy for diagnosis and treatment of GI-NENs is not fully understood.Objective
The current study analyzed GI-NENs, especially those diagnosed pathologically and resected endoscopically, and focused on the biopsy and cold biopsy forceps polypectomy (CBP) to analyze their roles in diagnosing and treating GI-NENs.Methods
Clinical data of all GI-NENs were reviewed from January 2006 to March 2012. Histopathology was used to diagnose GI-NENs, which were confirmed by immunohistochemistry.Results
67.96% GI-NENs were diagnosed pathologically by endoscopy. Only 26.21% were diagnosed pathologically by biopsies before treatment. The diagnostic rate was significantly higher in polypoid (76.47%) and submucosal lesions (68.75%), than in ulcerative lesions (12.00%). However, biopsies were only taken in 56.31% patients, including 51.52% of polypoid lesions, 35.56% of submucosal lesions and 100.00% of ulcerative lesions. Endoscopic resection removed 61.76% of GI-NENs, including six by CBP, 14 by snare polypectomy with electrocauterization, 28 by endoscopic mucosal resection (EMR) and 15 by endoscopic submucosal dissection (ESD). 51.52% polypoid GI-NENs had infiltrated the submucosa under microscopic examination. CBP had a significantly higher rate of remnant (33.33%) than snare polypectomy with electrocauterization, EMR and ESD (all 0.00%).Conclusions
Biopsies for all polypoid and submucosal lesions will improve pre-operative diagnosis. The high rate of submucosal infiltration of polypoid GI-NENs determined that CBP was inadequate in the treatment of GI-NENs. Diminutive polypoid GI-NENs that disappeared after CBP had a high risk of remnant and should be closely followed up over the long term. 相似文献46.
The α/β-type small acid soluble proteins (SASPs) are a major factor in protecting the spores from being killed in bacteria. In this article, we perform a systematic phylogenetic analysis of the α/β-type SASP in the genus of Geobacillus, which indicates that the whole family can be divided into three groups. We choose one protein from each group as a representative
and construct the tertiary structure of these proteins. In order to explore the mechanism of protecting DNA from damage, 15 ns
molecular dynamics simulation for the four complexes of Gsy3 with DNA are performed. The sequence alignment, model structure
and binding energy analysis indicate that the helix2 region of SASPs is more conserved and plays a more crucial role in protecting
DNA. Pairwise decomposition of residue interaction energies calculation demonstrate that amino acids of Asn10, Lys24, Asn49,
Ile52, Ile56, Thr57, Lys58, Arg59 and Val61 take major effect in the binding interaction. The differences of energy contribution
of the amino acids between different complexes make us conclude that the protein structure conformation has a slight change
upon more proteins binding to DNA and consequently there occur protein-protein cooperation interactions. 相似文献
47.
Cell wounding is an important driver of the innate immune response of ventilator-injured lungs. We had previously shown that the majority of wounded alveolus resident cells repair and survive deformation induced insults. This is important insofar as wounded and repaired cells may contribute to injurious deformation responses commonly referred to as biotrauma. The central hypothesis of this communication states that extracellular adenosine-5' triphosphate (ATP) promotes the repair of wounded alveolus resident cells by a P2Y2-Receptor dependent mechanism. Using primary type 1 alveolar epithelial rat cell models subjected to micropuncture injury and/or deforming stress we show that 1) stretch causes a dose dependent increase in cell injury and ATP media concentrations; 2) enzymatic depletion of extracellular ATP reduces the probability of stretch induced wound repair; 3) enriching extracellular ATP concentrations facilitates wound repair; 4) purinergic effects on cell repair are mediated by ATP and not by one of its metabolites; and 5) ATP mediated cell salvage depends at least in part on P2Y2-R activation. While rescuing cells from wounding induced death may seem appealing, it is possible that survivors of membrane wounding become governors of a sustained pro-inflammatory state and thereby perpetuate and worsen organ function in the early stages of lung injury syndromes. Means to uncouple P2Y2-R mediated cytoprotection from P2Y2-R mediated inflammation and to test the preclinical efficacy of such an undertaking deserve to be explored. 相似文献
48.
Rong Huang Sai Tian Rongrong Cai Jie Sun Wenqing Xia Xue Dong Yanjue Shen Shaohua Wang 《Journal of cellular and molecular medicine》2017,21(8):1448-1456
Saitohin (STH) Q7R polymorphism has been reported to influence the individual's susceptibility to Alzheimer's disease (AD); however, conclusions remain controversial. Therefore, we performed this meta‐analysis to explore the association between STH Q7R polymorphism and AD risk. Systematic literature searches were performed in the PubMed, Embase, Cochrane Library and Web of Science for studies published before 31 August 2016. Pooled odds ratios (ORs) and 95% confidence intervals (CIs) were calculated to assess the strength of the association using a fixed‐ or random‐effects model. Subgroup analyses, Galbraith plot and sensitivity analyses were also performed. All statistical analyses were performed with STATA Version 12.0. A total of 19 case–control studies from 17 publications with 4387 cases and 3972 controls were included in our meta‐analysis. The results showed that the Q7R polymorphism was significantly associated with an increased risk of AD in a recessive model (RR versus QQ+QR, OR = 1.27, 95% CI = 1.01–1.60, P = 0.040). After excluding the four studies not carried out in caucasians, the overall association was unchanged in all comparison models. Further subgroup analyses stratified by the time of AD onset, and the quality of included studies provided statistical evidence of significant increased risk of AD in RR versus QQ+QR model only in late‐onset subjects (OR = 1.56, 95% CI = 1.07–2.26, P = 0.021) and in studies with high quality (OR = 1.37, 95% CI = 1.01–1.86, P = 0.043). This meta‐analysis suggests that the RR genotype in saitohin Q7R polymorphism may be a human‐specific risk factor for AD, especially among late‐onset AD subjects and caucasian populations. 相似文献
49.
50.
Zhou G Li H DeCamp D Chen S Shu H Gong Y Flaig M Gillespie JW Hu N Taylor PR Emmert-Buck MR Liotta LA Petricoin EF Zhao Y 《Molecular & cellular proteomics : MCP》2002,1(2):117-124
The reproducibility of conventional two-dimensional (2D) gel electrophoresis can be improved using differential in-gel electrophoresis (DIGE), a new emerging technology for proteomic analysis. In DIGE, two pools of proteins are labeled with 1-(5-carboxypentyl)-1'-propylindocarbocyanine halide (Cy3) N-hydroxy-succinimidyl ester and 1-(5-carboxypentyl)-1'-methylindodi-carbocyanine halide (Cy5) N-hydroxysuccinimidyl ester fluorescent dyes, respectively. The labeled proteins are mixed and separated in the same 2D gel. 2D DIGE was applied to quantify the differences in protein expression between laser capture microdissection-procured esophageal carcinoma cells and normal epithelial cells and to define cancer-specific and normal-specific protein markers. Analysis of the 2D images from protein lysates of approximately 250,000 cancer cells and normal cells identified 1038 protein spots in cancer cell lysates and 1088 protein spots in normal cell lysates. Of the detected proteins, 58 spots were up-regulated by >3-fold and 107 were down-regulated by >3-fold in cancer cells. In addition to previously identified down-regulated protein annexin I, tumor rejection antigen (gp96) was found up-regulated in esophageal squamous cell cancer. Global quantification of protein expression between laser capture-microdissected patient-matched cancer cells and normal cells using 2D DIGE in combination with mass spectrometry is a powerful tool for the molecular characterization of cancer progression and identification of cancer-specific protein markers. 相似文献