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   59399篇
  免费   4689篇
  国内免费   1605篇
耳鼻咽喉   740篇
儿科学   823篇
妇产科学   1270篇
基础医学   9059篇
口腔科学   1771篇
临床医学   4897篇
内科学   11771篇
皮肤病学   1160篇
神经病学   4243篇
特种医学   2003篇
外国民族医学   6篇
外科学   8146篇
综合类   4000篇
现状与发展   1篇
一般理论   8篇
预防医学   3559篇
眼科学   1473篇
药学   5224篇
中国医学   796篇
肿瘤学   4743篇
  2023年   239篇
  2022年   454篇
  2021年   766篇
  2020年   481篇
  2019年   835篇
  2018年   1391篇
  2017年   1036篇
  2016年   1072篇
  2015年   1209篇
  2014年   1580篇
  2013年   1915篇
  2012年   2640篇
  2011年   2580篇
  2010年   1529篇
  2009年   1485篇
  2008年   2218篇
  2007年   2322篇
  2006年   2122篇
  2005年   1774篇
  2004年   1619篇
  2003年   1578篇
  2002年   1471篇
  2001年   4812篇
  2000年   4708篇
  1999年   4078篇
  1998年   1443篇
  1997年   1061篇
  1996年   645篇
  1995年   537篇
  1994年   480篇
  1993年   439篇
  1992年   2009篇
  1991年   1756篇
  1990年   1608篇
  1989年   1528篇
  1988年   1334篇
  1987年   1248篇
  1986年   1109篇
  1985年   955篇
  1984年   628篇
  1983年   500篇
  1982年   264篇
  1981年   198篇
  1980年   160篇
  1979年   318篇
  1978年   97篇
  1974年   102篇
  1973年   121篇
  1972年   89篇
  1969年   89篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
In the work described here, our aim was to determine, in an elderly population, changes in muscle thickness (MT), cross-sectional area (CSA) and echo intensity (EI) of the quadriceps muscles at four time points (0, 5, 10 and 15 min; i.e., T0, T5, T10 and T15, respectively) after changing from a standing to supine position. Twenty-one elderly participants (14 men: 68.1 ± 4.6 y; 8 women: 66.8 ± 4.1 y) were evaluated at four time points. Rectus femoris CSA (RFCSA), MT and EI of the quadriceps femoris (QF) muscles were assessed. EI significantly increased from T0 to T5, T10 and T15 (p < 0.001), whereas no differences were observed between T5 and T15 in the rectus femoris (RFEI), vastus intermedius (VIEI) and quadriceps femoris (QFEI). No differences were observed between any time points in the RFCSA and MT of QF muscles. In summary, these results suggest that periods >5 min are not necessary to obtain consistent MT and EI measurements of quadriceps femoris muscles in the elderly population.  相似文献   
4.
Changes in resting energy expenditure (REE) of cancer patients vary depending on type of tumor, treatment time point and kind of treatment. Little is known about REE of acute leukemia adult patients after treatment, especially with results related to body weight or fat free mass (FFM). This study aimed to assess changes in REE of acute leukemia adult patients before and after the first remission induction. Evaluation of REE was performed by indirect calorimetry and predicted REE was calculated by Harris-Benedict equation. Weight and height were measured and compared to a control group of healthy individuals. FFM was assessed by bioelectrical impedance for adjusting REE values. We evaluated 18 patients and 26 healthy individuals. At diagnosis, patients presented REE, REE/weight, and REE/FFM higher than the controls. Reductions of REE, REE/weight, and REE/FFM were also observed in patients after the first cycle of chemotherapy. The predicted REE for the patients group showed significant lower value compared with measured REE. Before the first cycle of chemotherapy REE was increased but undergoes a reduction after treatment, reaching values similar to the controls. For predictive Harris-Benedict equation, stress factors should be added to avoid underestimation of REE before and after chemotherapy.  相似文献   
5.
6.
7.
8.
9.
10.
Loss of function variants in NOTCH1 cause left ventricular outflow tract obstructive defects (LVOTO). However, the risk conferred by rare and noncoding variants in NOTCH1 for LVOTO remains largely uncharacterized. In a cohort of 49 families affected by hypoplastic left heart syndrome, a severe form of LVOTO, we discovered predicted loss of function NOTCH1 variants in 6% of individuals. Rare or low-frequency missense variants were found in 16% of families. To make a quantitative estimate of the genetic risk posed by variants in NOTCH1 for LVOTO, we studied associations of 400 coding and noncoding variants in NOTCH1 in 1,085 cases and 332,788 controls from the UK Biobank. Two rare intronic variants in strong linkage disequilibrium displayed significant association with risk for LVOTO amongst European-ancestry individuals. This result was replicated in an independent analysis of 210 cases and 68,762 controls of non-European and mixed ancestry. In conclusion, carrying rare predicted loss of function variants in NOTCH1 confer significant risk for LVOTO. In addition, the two intronic variants seem to be associated with an increased risk for these defects. Our approach demonstrates the utility of population-based data sets in quantifying the specific risk of individual variants for disease-related phenotypes.  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