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   6783篇
  免费   372篇
  国内免费   37篇
耳鼻咽喉   211篇
儿科学   161篇
妇产科学   220篇
基础医学   936篇
口腔科学   376篇
临床医学   535篇
内科学   1548篇
皮肤病学   115篇
神经病学   512篇
特种医学   159篇
外科学   1051篇
综合类   32篇
预防医学   528篇
眼科学   145篇
药学   346篇
中国医学   35篇
肿瘤学   282篇
  2023年   51篇
  2022年   112篇
  2021年   206篇
  2020年   120篇
  2019年   200篇
  2018年   210篇
  2017年   126篇
  2016年   174篇
  2015年   242篇
  2014年   313篇
  2013年   351篇
  2012年   535篇
  2011年   598篇
  2010年   353篇
  2009年   273篇
  2008年   457篇
  2007年   479篇
  2006年   451篇
  2005年   385篇
  2004年   350篇
  2003年   290篇
  2002年   268篇
  2001年   82篇
  2000年   71篇
  1999年   63篇
  1998年   51篇
  1997年   35篇
  1996年   27篇
  1995年   20篇
  1994年   22篇
  1993年   15篇
  1992年   20篇
  1991年   29篇
  1990年   23篇
  1989年   18篇
  1988年   19篇
  1987年   16篇
  1986年   14篇
  1985年   12篇
  1984年   12篇
  1983年   9篇
  1982年   10篇
  1981年   10篇
  1980年   14篇
  1979年   9篇
  1978年   7篇
  1976年   6篇
  1975年   6篇
  1973年   6篇
  1970年   4篇
排序方式: 共有7192条查询结果,搜索用时 15 毫秒
81.
BackgroundPatients with a first episode of psychosis (FEP) are at higher risk of gaining weight and presenting metabolic disturbances, partly related to antipsychotic exposure. Previous studies suggest that treatment discontinuation might have a positive impact on weight in schizophrenia. The aim of this study was to evaluate the effect of treatment discontinuation on weight and metabolic changes in a FEP cohort.MethodsA total of 209 FEP patients and 57 healthy controls were evaluated at study entry and prospectively at 10-year follow-up. Anthropometric measures and, clinical, metabolic, and sociodemographic data were collected.ResultsPatients discontinuing antipsychotic treatment presented a significantly lower increase in weight and better metabolic parameter results than those still on antipsychotic treatment at 10-year follow-up.ConclusionsTreatment discontinuation had a positive effect on the weight and metabolic changes observed in FEP patients; however, this effect was not sufficient to reaching a complete reversal to normal levels.  相似文献   
82.
Background: Few electrocardiographic parameters beyond the QRS duration were studied with regard to the correlation with mechanical dyssynchrony. This study aims to analyze the correlation between electrocardiographic parameters and mechanical dyssynchrony in patients with symptomatic heart failure (HF) and left bundle branch block (LBBB). Methods: Patients with HF, ejection fraction ≤ 35%, and QRS interval ≥ 120 ms with a LBBB were prospectively studied. We analyzed the correlation between electrocardiographic parameters (QRS duration, R voltage in limb leads, S voltage in precordial leads, Sokolow and Cornell indexes, QRS axis deviation, and QRS notches in lateral and inferior leads) and mechanical dyssynchrony measured by tissue Doppler imaging (TDI). Results: A group of 50 patients were studied, 60% male, 78% with nonischemic cardiomyopathy, NYHA Class III–IV (86%), and ejection fraction of 0.22 ± 0.6. Intra‐ and interventricular dyssynchrony occurred in 68% and 74% of patients, respectively. The S amplitude in precordial leads and the Sokolow and Cornel indexes show a weak correlation with the degree of dyssynchrony. In the patients with QRS notching in the lateral and inferior leads, we observed significantly greater prevalence of intraventricular dyssynchrony, with sensitivity and specificity of 85% and 56%, respectively, for notches in lateral leads. The QRS duration presents moderate correlation with the degree of both intraventricular (r = 0.48) and interventricular dyssynchrony (r = 0.46). Conclusion: The following electrocardiographic parameters were related to the degree of mechanical dyssynchrony: QRS duration and notches in QRS. In addition, the patients tend to have highest S amplitude in precordial leads. Ann Noninvasive Electrocardiol 2011;16(1):41–48  相似文献   
83.
84.
85.
The methane-rich, hydrothermally heated sediments of the Guaymas Basin are inhabited by thermophilic microorganisms, including anaerobic methane-oxidizing archaea (mainly ANME-1) and sulfate-reducing bacteria (e.g., HotSeep-1 cluster). We studied the microbial carbon flow in ANME-1/ HotSeep-1 enrichments in stable-isotope–probing experiments with and without methane. The relative incorporation of 13C from either dissolved inorganic carbon or methane into lipids revealed that methane-oxidizing archaea assimilated primarily inorganic carbon. This assimilation is strongly accelerated in the presence of methane. Experiments with simultaneous amendments of both 13C-labeled dissolved inorganic carbon and deuterated water provided further insights into production rates of individual lipids derived from members of the methane-oxidizing community as well as their carbon sources used for lipid biosynthesis. In the presence of methane, all prominent lipids carried a dual isotopic signal indicative of their origin from primarily autotrophic microbes. In the absence of methane, archaeal lipid production ceased and bacterial lipid production dropped by 90%; the lipids produced by the residual fraction of the metabolically active bacterial community predominantly carried a heterotrophic signal. Collectively our results strongly suggest that the studied ANME-1 archaea oxidize methane but assimilate inorganic carbon and should thus be classified as methane-oxidizing chemoorganoautotrophs.  相似文献   
86.
87.
88.
ObjectiveTo investigate whether there is association between the rs20541 (R130Q) polymorphism in the IL-13 gene with disease susceptibility and clinical subsets in patients with elderly-associated inflammatory chronic diseases.Material and methods78 patients with giant cell arteritis (GCA), 174 with polymyalgia rheumatica (PMR), 90 elderly-onset rheumatoid arthritis (EORA), and 465 healthy controls from the same geographic area were studied. The rs20541 (R130Q) polymorphism in the IL-13 gene was evaluated by PCR-RFLP. Circulating levels of IL-13 were measured by ELISA.ResultsA higher frequency of the AA genotype [2.349 (0.994-5.554)], as well as the allele A [1.589 (1.085-2.328] and the A carriers [1.656 (1.021-2.686)] (p < 0.05) was observed in the GCA patients. No significant differences were observed in the PMR and EORA patients as compared with the healthy controls. Neither difference was observed among the different disease groups studied. In GCA patients, differences in the genotype were associated with a worse prognosis. In PMR patients, the AA genotype was associated with higher levels of serum IL-13 than the GA one. However, such an association was not detected for controls and the other disease groups.ConclusionsGCA is more frequent in carriers of the rs20541 (R130Q) polymorphism in the IL-13 gene. The utility of this polymorphism to predict the GCA prognosis must be confirmed in studies with a higher number of patients.  相似文献   
89.
90.
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