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   4668篇
  免费   423篇
  国内免费   10篇
耳鼻咽喉   40篇
儿科学   124篇
妇产科学   114篇
基础医学   490篇
口腔科学   58篇
临床医学   540篇
内科学   1046篇
皮肤病学   48篇
神经病学   373篇
特种医学   281篇
外科学   936篇
综合类   84篇
一般理论   5篇
预防医学   543篇
眼科学   87篇
药学   189篇
中国医学   1篇
肿瘤学   142篇
  2021年   48篇
  2020年   42篇
  2019年   70篇
  2018年   85篇
  2016年   42篇
  2015年   52篇
  2014年   82篇
  2013年   125篇
  2012年   138篇
  2011年   184篇
  2010年   100篇
  2009年   101篇
  2008年   177篇
  2007年   194篇
  2006年   197篇
  2005年   215篇
  2004年   206篇
  2003年   188篇
  2002年   197篇
  2001年   185篇
  2000年   188篇
  1999年   140篇
  1998年   71篇
  1997年   58篇
  1996年   59篇
  1995年   58篇
  1994年   53篇
  1993年   57篇
  1992年   140篇
  1991年   136篇
  1990年   95篇
  1989年   117篇
  1988年   118篇
  1987年   109篇
  1986年   117篇
  1985年   87篇
  1984年   84篇
  1983年   46篇
  1982年   52篇
  1981年   38篇
  1980年   38篇
  1979年   47篇
  1978年   46篇
  1977年   51篇
  1976年   41篇
  1975年   46篇
  1974年   45篇
  1973年   38篇
  1972年   45篇
  1968年   30篇
排序方式: 共有5101条查询结果,搜索用时 8 毫秒
1.
2.
3.
We have investigated the role of basal insulin concentration on leucine kinetics (determined by means of 1-[13C]leucine) and energy metabolism (determined by indirect calorimetry) in eight septic patients by reducing insulin (and glucagon) secretion by somatostatin infusion. Basal glucagon concentration was elevated (744 +/- 381 pg/mL), and insulin concentration was normal (10 +/- 4 microU/mL). Basal resting energy expenditure (REE) was 151 +/- 8% that of predicted basal energy expenditure, and leucine appearance (Ra), oxidation, and nonoxidative disposal rates were all elevated above the normal ranges. Somatostatin infusion reduced insulin concentration by 52% and glucagon concentration by 64%. This resulted in a significant increase in the rate of leucine oxidation from 0.96 +/- 0.08 to 1.18 +/- 0.14 mumol/kg/min (p less than 0.01), and nonoxidative leucine disposal decreased from 2.95 +/- 0.18 to 2.67 +/- 0.17 mumol/kg/min (p less than 0.01). Somatostatin infusion also caused significant increases in REE and fat oxidation from 1310 +/- 100 to 1505 +/- 128 kcal/m2/day (p less than 0.05) and from 1.72 +/- 0.24 to 2.41 +/- 0.41 mg/kg/min, respectively, and a slight decrease of carbohydrate oxidation from 1.51 +/- 0.49 to 1.31 +/- 0.49 mg/kg/min. These metabolic responses can be attributed to the reduction in insulin concentration, because they are in the opposite direction of changes that would occur as a consequence of a reduction in glucagon concentration. We conclude that the basal insulin plays an important role in attenuating net protein loss and energy expenditure.  相似文献   
4.
We describe the presence of cylindrical spirals on muscle biopsy from a 31-year-old man who developed rhabodomyolysis following a long run. He had a prior history of exertional cramps and myoglobinuria. His maternal grandfather had similar symptoms. Transmission electron micrographs demonstrated continuity between the lamellae of the cylindrical spirals and native myofilaments. Whether these unusual structures confer a derangement in myofilament function is uncertain.  相似文献   
5.
6.
7.
8.
Valid classification of stroke is essential to initiate effective acute management and early secondary prevention strategies. To accurately evaluate stroke subtype a number of diagnostic procedures have to be performed. This study sought to investigate variations in use of diagnostic procedures across selected European hospitals. First-ever stroke patients were sampled over a 1-year period through 11 hospital-based registers across 10 European countries. We defined a diagnostic standard for valid aetiological classification of ischemic stroke including brain imaging, vascular imaging and echocardiography. The impact of socio-demographic, clinical and structural characteristics on performance of the diagnostic standard was assessed using multivariate logistic regression analyses. A total of 1721 patients were included in the study. 83.1% received brain imaging, ranging from 32.8% to 100%. The diagnostic standard was performed in 40.4% of stroke patients, ranging from 0% to 77.2%. Patients with increasing age ( P  < 0.001) and with more severe strokes ( P  = 0.001) were less probably to receive the diagnostic standard. Patients treated in stroke units and neurological departments were more frequently investigated with the diagnostic standard ( P  < 0.001). Less than half of hospitalized stroke patients across Europe underwent diagnostic procedures to allow for aetiological classification of stroke, which may hamper the initiation of effective early management and secondary prevention.  相似文献   
9.
Reports suggest that response tointerferon-alpha therapy is influenced by both hepatitisC viral genotype and titer. Our aim was to determine ifdirect, automated, cycle sequencing of the PCR productfrom an HCV RNA detection assay could be used toreliably determine HCV genotype. In addition, theapproach was used to determine the HCV genotypedistribution in our patient population and to learn ifthere was a correlation between HCV genotype and RNAtiter that could be used to predict response totreatment. In all 143 consecutive patients were testedfor both HCV RNA titer and genotype. Automated, cycle sequencing of PCR product was highly effectiveand failed to yield a genotype in only 3 (2%) patients.The distribution of HCV genotypes was: 1a (40%), 1b(39%), 2a (2%), 2b (6%), 3a (4%). There were significant differences in the median HCV RNA titersbetween genotypes 1, 2, and 3. 6 High HCV RNA titers>4.4 × 106 copies/ml were only seenin genotype 1. However, the HCV RNA level should not beused as a surrogate marker of genotype because of a significantoverlap of titers within the genotypes.  相似文献   
10.
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