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   89753篇
  免费   7094篇
  国内免费   4275篇
耳鼻咽喉   1207篇
儿科学   1061篇
妇产科学   866篇
基础医学   9760篇
口腔科学   1564篇
临床医学   8987篇
内科学   13281篇
皮肤病学   1404篇
神经病学   4218篇
特种医学   4453篇
外国民族医学   8篇
外科学   11886篇
综合类   14404篇
现状与发展   15篇
一般理论   16篇
预防医学   6344篇
眼科学   2004篇
药学   8670篇
  57篇
中国医学   4341篇
肿瘤学   6576篇
  2024年   179篇
  2023年   881篇
  2022年   2224篇
  2021年   3344篇
  2020年   2445篇
  2019年   2255篇
  2018年   2532篇
  2017年   2400篇
  2016年   2541篇
  2015年   3792篇
  2014年   4806篇
  2013年   5316篇
  2012年   7834篇
  2011年   7974篇
  2010年   5944篇
  2009年   5139篇
  2008年   5989篇
  2007年   5799篇
  2006年   5407篇
  2005年   4662篇
  2004年   3641篇
  2003年   3453篇
  2002年   3024篇
  2001年   2250篇
  2000年   1625篇
  1999年   1103篇
  1998年   524篇
  1997年   516篇
  1996年   369篇
  1995年   305篇
  1994年   262篇
  1993年   171篇
  1992年   255篇
  1991年   276篇
  1990年   205篇
  1989年   191篇
  1988年   167篇
  1987年   185篇
  1986年   145篇
  1985年   128篇
  1984年   86篇
  1983年   86篇
  1982年   52篇
  1979年   72篇
  1978年   43篇
  1977年   46篇
  1975年   46篇
  1974年   46篇
  1973年   44篇
  1969年   45篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
Abstract

Background

Comorbidities are commonly seen in patients with coronavirus disease 2019 (COVID-19), but the clinical implication is not yet well-delineated. We aim to characterize the prevalence and clinical implications of comorbidities in patients with COVID-19.  相似文献   
2.
Levels of the soluble form of the triggering receptor expressed on myeloid cells (sTREM)-1 are elevated in severe sepsis. However, it is not known whether sTREM-1 measurements can distinguish milder bacterial infections from noninfectious inflammation. The present authors studied whether serum sTREM-1 levels differ in community-acquired pneumonia, exacerbations of chronic obstructive pulmonary disease (COPD), asthma and controls, and whether sTREM-1 may be used as a surrogate marker for the need for antibiotics. Serum sTREM-1 levels in 150 patients with pneumonia, COPD and asthma exacerbations and 62 healthy controls were measured. Serum sTREM-1 levels were significantly elevated in pneumonia (median 295.2 ng x mL(-1)), COPD (280.3 ng x mL(-1)) and asthma exacerbations (184.0 ng x mL(-1)) compared with controls (83.1 ng x mL(-1)). Levels were higher in pneumonia and Anthonisen type 1 COPD exacerbations than in type 2 and 3 COPD and asthma exacerbations. The area under the receiver operating characteristics curve for sTREM-1 as a surrogate marker for the need for antibiotics was 0.77. Serum levels of the soluble form of the triggering receptor expressed on myeloid cells-1 were elevated predominantly in pneumonia and Anthonisen type 1 COPD exacerbations versus type 2 and 3 chronic obstructive pulmonary disease exacerbations, asthma and controls. Serum levels of the soluble form of the triggering receptor expressed on myeloid cells-1 has moderate but insufficient accuracy as a surrogate marker for the need for antibiotics in lower respiratory tract infections.  相似文献   
3.
The response of single detergent treated bovine retinal pigment epithelial cells in culture to ATP was measured with an image analyser. The most pronounced contraction was produced by 1.0 mM ATP with most change taking place in the first 10 min. At 1 h the area had decreased by about 33%, perimeter 22% and maximum length 25%. By way of comparison rabbit skin fibroblasts had a decreased area of approximately 40%, perimeter 25% and maximum length 22%. Bovine aortic smooth muscle cells on the other hand decreased in area by 55%, perimeter 40% and maximum length 36%. It is hoped that this assay may be used to evaluate drugs which could counteract contractile events in proliferative vitreoretinopathy.  相似文献   
4.
5.
目的:观察喉罩全麻下行颈动脉狭窄的造影诊断及介入治疗术的临床效果。方法:择期DSA下颈动脉狭窄患者23例,年龄42-78岁,无明显肺部疾患及喉罩禁忌症患者,异丙酚(Pmpofol)泵入静脉全麻下插入喉罩完成手术,观察其不同时段的BP(MAP)、SpO2、HR、ECG(ST-Ⅱ)。结果:各时段的BP(MAP)、Sp02、HR、ECG(ST-Ⅱ)比较无显著性差异。结论:喉罩全麻在行颈动脉狭窄的造影诊断及介入治疗术的临床效果是肯定的。喉罩全麻颈动脉狭窄造影介入治疗  相似文献   
6.
7.
目的:寻找能提高治疗周围性面瘫疗效的适宜的电针波型.方法:将147例周围性面瘫患者随机分为治疗组和对照组,治疗组进行穴位分组,电针波型先用连续波后用疏密波治疗;对照组穴位不分组,并单纯采用连续波治疗.结果:两组的总有效率和痊愈所用时间经统计学处理,差异有非常显著性意义(P<0.01).结论:在电针治疗周围性面瘫中,将疏密波和连续波配合使用,效果显著优于单纯使用连续波者.  相似文献   
8.
支架内血栓形成是支架置入术后的一种常见并发症。术后血管内皮损伤、胶原组织暴露和作为异物的支架均为引发血栓形成的可能机制。不能及时识别处理则成为再狭窄的重要原因。我们报告1例发生在大脑中动脉(middle cerebral artery,MCA)支架内的血栓形成,探讨其识别处理过程和可能的机制。  相似文献   
9.
Esophageal perforation is associated with a significant risk of morbidity and mortality. We report herein a case of lye-induced esophageal perforation managed successfully by employing endoscopic T-tube placement with a successful outcome.  相似文献   
10.
Background contextIt was recently demonstrated that the postnatal transition from a notochordal to a fibrocartilaginous nucleus pulposus (NP) is accomplished exogenously by chondrocytes migrating from hyaline cartilage end plates (CEs) into the ectopic notochordal NP region. Although our previous in vivo studies showed evidences for the migration of CE chondrocyte from hyaline CEs into the notochordal NP, it is unknown whether CE chondrocytes of the intervertebral disc (IVD) really have a motile property. In addition, the effect of notochordal cells on this property has not been elucidated.PurposeThe purpose of this in vitro study was to demonstrate whether CE chondrocytes of the IVD are capable of migration, and whether there is any biological link between notochordal cells and CE chondrocytes that may regulate the CE chondrocyte migration.Study design/settingIn vitro cell migration assays were performed using rat IVDs.MethodsNotochordal cells and chondrocytes were obtained from the NP and CE tissues, respectively, and were cultured separately. The different numbers of notochordal cells and the supernatant (conditioned medium) that contained soluble factors produced by notochordal cells were used to demonstrate their effects on the migration of CE chondrocytes. Bovine serum albumin (BSA) and lysophosphatidic acid (LPA) were used as negative and positive controls, respectively.ResultsCompared with BSA, LPA, notochordal cells (N=4×, 2×, 1×, and 0.5×105), and its conditioned media (unconcentrated and fivefold concentrated) significantly increased migration of CE chondrocytes (p<.05 in all comparisons). Particularly, notochordal cells and its conditioned media increased migration in a number- and concentration-dependent manner, respectively.ConclusionsThis study demonstrates that CE chondrocytes of the IVD are capable of migration and that soluble factors produced by notochordal cells stimulate the migration. These results provide a plausible explanation to the question of why CE chondrocytes of the IVD migrate into the ectopic NP region during the natural transition from the notochordal to fibrocartilaginous NP.  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