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   3739篇
  免费   94篇
  国内免费   18篇
耳鼻咽喉   31篇
儿科学   100篇
妇产科学   175篇
基础医学   689篇
口腔科学   63篇
临床医学   412篇
内科学   461篇
皮肤病学   77篇
神经病学   100篇
特种医学   272篇
外科学   528篇
综合类   109篇
预防医学   284篇
眼科学   75篇
药学   289篇
中国医学   3篇
肿瘤学   183篇
  2022年   41篇
  2021年   52篇
  2019年   31篇
  2018年   33篇
  2016年   42篇
  2015年   44篇
  2014年   59篇
  2013年   60篇
  2012年   99篇
  2011年   146篇
  2010年   100篇
  2009年   72篇
  2008年   123篇
  2007年   139篇
  2006年   135篇
  2005年   126篇
  2004年   110篇
  2003年   92篇
  2002年   73篇
  2001年   79篇
  2000年   104篇
  1999年   85篇
  1998年   65篇
  1997年   49篇
  1996年   38篇
  1995年   33篇
  1994年   34篇
  1993年   32篇
  1992年   72篇
  1991年   110篇
  1990年   117篇
  1989年   125篇
  1988年   113篇
  1987年   144篇
  1986年   115篇
  1985年   100篇
  1984年   71篇
  1983年   56篇
  1982年   35篇
  1979年   48篇
  1978年   29篇
  1977年   38篇
  1976年   45篇
  1975年   51篇
  1974年   69篇
  1973年   51篇
  1972年   48篇
  1971年   40篇
  1970年   45篇
  1969年   34篇
排序方式: 共有3851条查询结果,搜索用时 0 毫秒
101.
102.
To determine the phenotype and natural history of a founder genetic subtype of autosomal dominant arrhythmogenic right ventricular cardiomyopathy (ARVC) caused by a p.S358L mutation in TMEM43. The age of onset of cardiac symptoms, clinical events and test abnormalities were studied in 412 subjects (258 affected and 154 unaffected), all of which occurred in affected males significantly earlier and more often than unaffected males. Affected males were hospitalized four times more often than affected females (p ≤ 0.0001) and died younger (p ≤ 0.001). The temporal sequence from symptoms onset to death was prolonged in affected females by 1–2 decades. The most prevalent electrocardiogram (ECG) manifestation was poor R wave progression (PRWP), with affected males twice as likely to develop PRWP as affected females (p ≤ 0.05). Left ventricular enlargement (LVE) occurred in 43% of affected subjects, with 11% fulfilling criteria for dilated cardiomyopathy. Ventricular ectopy on Holter monitor was common and occurred early: the most diagnostically useful clinical test. No symptom or test could rule out diagnosis. This ARVC subtype is a sex‐influenced lethal arrhythmogenic cardiomyopathy, with a unique ECG finding, LV dilatation, heart failure and early death, where molecular pre‐symptomatic diagnosis has the greatest clinical utility.  相似文献   
103.
Journal of NeuroVirology - The clinical manifestations of neurological complications associated with varicella zoster virus (VZV) are non-specific and indistinguishable from those of other viral...  相似文献   
104.
105.
106.
The intensifying of the manufacturing process and increasing the efficiency of production planning of precise and non-rigid parts, mainly crankshafts, are the first-priority task in modern manufacturing. The use of various methods for controlling the cutting force under cylindrical infeed grinding and studying its impact on crankpin machining quality and accuracy can improve machining efficiency. The paper deals with developing a comprehensive scientific and methodological approach for determining the experimental dependence parameters’ quantitative values for cutting-force calculation in cylindrical infeed grinding. The main stages of creating a method for conducting a virtual experiment to determine the cutting force depending on the array of defining parameters obtained from experimental studies are outlined. It will make it possible to get recommendations for the formation of a valid route for crankpin machining. The research’s scientific novelty lies in the developed scientific and methodological approach for determining the cutting force, based on the integrated application of an artificial neural network (ANN) and multi-parametric quasi-linear regression analysis. In particular, on production conditions, the proposed method allows the rapid and accurate assessment of the technological parameters’ influence on the power characteristics for the cutting process. A numerical experiment was conducted to study the cutting force and evaluate its value’s primary indicators based on the proposed method. The study’s practical value lies in studying how to improve the grinding performance of the main bearing and connecting rod journals by intensifying cutting modes and optimizing the structure of machining cycles.  相似文献   
107.
Graft-copolymers based on bioresorbable synthetic (oligo-/polylactide) and natural (chitosan and collagen/gelatin) components were synthesized through solid-state reactive co-extrusion and used for fabrication of fibrous non-woven mats via the electrospinning technique. The effect of the macromolecular features of the initial components on the copolymer characteristics was evaluated using FTIR-spectroscopy, differential scanning calorimetry and elemental analysis. Dynamic light scattering analysis showed that the copolymers have a tendency to form stable ultra-fine dispersions with a mean size of macromolecular aggregates of 150 nm within chlorinated solvents. The copolymer-containing non-woven fibrous mats were fabricated via an electrospinning procedure using chloroform as a solvent. An effect of the copolymer composition on the casting solution''s viscosity, conductivity and surface tension was evaluated. Scanning electron microscopy showed that the obtained mats consist of randomly distributed fibers with a mean size of ∼5 μm and a more complex morphology than mats fabricated from neat polylactide. The proposed mechanochemical approach to obtain hybrid copolymeric compositions differs from typical liquid-phase methods in terms of high efficiency, simplicity and cleanness.

Amphiphilic chitosan-g-oligo/polylactide graft-copolymers were synthesized through solid-state reactive co-extrusion and used for fabrication of fibrous non-woven mats via the electrospinning technique using chloroform as a solvent.  相似文献   
108.
109.
110.
Tripartite motif protein TRIM5α blocks retroviral replication after cell entry, and species-specific differences in its activity are determined by sequence variations within the C-terminal B30.2/PRYSPRY domain. Here we report a high-resolution structure of a TRIM5α PRYSPRY domain, the PRYSPRY of the rhesus monkey TRIM5α that potently restricts HIV infection, and identify features involved in its interaction with the HIV capsid. The extensive capsid-binding interface maps on the structurally divergent face of the protein formed by hypervariable loop segments, confirming that TRIM5α evolution is largely determined by its binding specificity. Interactions with the capsid are mediated by flexible variable loops via a mechanism that parallels antigen recognition by IgM antibodies, a similarity that may help explain some of the unusual functional properties of TRIM5α. Distinctive features of this pathogen-recognition interface, such as structural plasticity conferred by the mobile v1 segment and interaction with multiple epitopes, may allow restriction of divergent retroviruses and increase resistance to capsid mutations.  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