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   1234篇
  免费   93篇
  国内免费   13篇
耳鼻咽喉   12篇
儿科学   27篇
妇产科学   34篇
基础医学   172篇
口腔科学   48篇
临床医学   142篇
内科学   266篇
皮肤病学   28篇
神经病学   116篇
特种医学   28篇
外科学   109篇
综合类   17篇
预防医学   156篇
眼科学   35篇
药学   83篇
中国医学   11篇
肿瘤学   56篇
  2024年   3篇
  2023年   20篇
  2022年   55篇
  2021年   89篇
  2020年   44篇
  2019年   57篇
  2018年   66篇
  2017年   53篇
  2016年   50篇
  2015年   76篇
  2014年   55篇
  2013年   66篇
  2012年   123篇
  2011年   98篇
  2010年   72篇
  2009年   51篇
  2008年   77篇
  2007年   58篇
  2006年   51篇
  2005年   45篇
  2004年   38篇
  2003年   37篇
  2002年   23篇
  2001年   3篇
  2000年   2篇
  1999年   2篇
  1998年   6篇
  1997年   2篇
  1996年   6篇
  1995年   2篇
  1993年   1篇
  1992年   2篇
  1991年   1篇
  1985年   3篇
  1984年   1篇
  1982年   1篇
  1972年   1篇
排序方式: 共有1340条查询结果,搜索用时 4 毫秒
21.
22.
23.
Clinical Rheumatology - MiRSNPs may interfere with mRNA stability through effects on microRNAs (miRNAs)-mRNA interactions via direct changes in miRNA binding site or effect on the secondary...  相似文献   
24.
25.
26.
Clinical and Experimental Medicine - The development of new therapies based on tumor biology is one of the main topics in cancer treatment. In this regard, investigating the...  相似文献   
27.
28.
Background: Previous studies have demonstrated that bone demineralization can improve consolidation in bone grafts. The biologic mechanisms underlying this phenomenon remain unclear. Methods: Twelve adult male guinea pigs were used in this experiment. Forty‐five bone samples removed from the calvaria of nine animals were divided in groups (n = 9) according to the time of demineralization with citric acid (50%, pH 1): 15, 30, 90, and 180 seconds and non‐demineralized samples (control). Preosteoblasts (MC3T3‐E1) were cultured on the bone samples for 24, 48, and 72 hours (n = 3). Fifteen samples removed from the remaining three animals were analyzed by scanning electron microcopy/energy dispersive spectrometry (SEM/EDS) after demineralization (n = 3). Results: The number of preosteoblasts increased significantly with time in all groups. The bone surface area covered by these cells increased with time, except in the control group. Intragroup differences occurred between 24 and 72 hours (P <0.05). Samples demineralized for 30 seconds showed greater area covered by preosteoblast cells than for the other times of demineralization in all periods of cell culture (P <0.05) without a statistically significant difference compared with 15 seconds. SEM/EDS showed diminished content of calcium (Ca) after 15 seconds of demineralization, but the Ca content increased after 180 seconds of demineralization (P <0.05). The phosphorus (P) amount increased significantly only after 30 seconds of demineralization (P <0.5). The sulfur (S) content was increased in demineralized samples in relation to non‐demineralized ones, reaching the highest level after 90 seconds, when the difference became significant in relation to all the other times of demineralization (P <0.05). Magnesium (Mg) content did not differ significantly between demineralized and non‐demineralized samples. Conclusions: Bone surfaces demineralized for 30 seconds increased the spreading of preosteoblasts as well as the surface area covered by these cells. Bone demineralization deserves to be studied in periodontal and maxillofacial regenerative procedures.  相似文献   
29.
[Purpose] Obesity is a global health problem and is associated with a multitude of complications. This study was designed to determine changes in cardiopulmonary functions after aerobic and anaerobic exercise training in obese subjects. [Subjects and Methods] Forty obese subjects, whose ages ranged between 18 and 25 years, were divided into 2 equal groups: group A received aerobic exercise training in addition to dietary measures, and group B received anaerobic exercise training for 3 months in addition to dietary measures. Measurements of systolic blood pressure, diastolic blood pressure, heart rate, maximum voluntary ventilation, maximal oxygen consumption, and body mass index were obtained for both groups before and after the exercise program. [Results] The mean body mass index, systolic blood pressure, diastolic blood pressure, heart rate, and maximal oxygen consumption decreased significantly, whereas the mean maximum voluntary ventilation increased significantly after treatment in group A. The mean maximum voluntary ventilation also increased significantly after treatment in group B. There were significant differences between the mean levels of the investigated parameters in groups A and B after treatment. [Conclusion] Aerobic exercise reduces weight and improves cardiopulmonary fitness in obese subjects better than anaerobic exercise.Key words: Obesity, Aerobic, Anaerobic  相似文献   
30.
Patients in an intensive care unit (ICU) under mechanical ventilation (MV) are very difficult to image by transthoracic echocardiography, diminishing the beneficial information that could be obtained by this noninvasive approach. The objective of this study is to assess whether the addition of a contrast agent to fundamental imaging (FI) can improve or change the initial diagnosis in cardiac postoperative patients under mechanical ventilation by enhancing endocardial border delineation and Doppler flow signal. Thirty mechanically ventilated post-cardiac surgery patients (20 men, mean age 61 +/- 13 years) were evaluated with FI before and after intravenous injection of contrast. Left ventricular endocardial border delineation score index (EBDSI), estimated left ventricular ejection fraction (LVEF), and color and spectral Doppler were analyzed. The use of contrast resulted in a significant increase in the number of well-delineated segments, with a salvage rate of 77% of nondiagnostic studies. EBDSI was 1.62 +/- 0.61, before contrast, increasing to 2.05 +/- 0.53 after it (P < 0.001). There was a change in the LVEF estimation in 5 exams, and a new wall motion abnormality was detected in other 4 exams, after the use of contrast. Moreover, a significant change was observed in the quantification of mitral regurgitation in 5 patients, in the aortic transvalvular peak gradient in 1 patient, and measurement of tricuspid regurgitation peak flow velocity in 8 patients. It is concluded that in cardiac postoperative patients under mechanical ventilation, intravenous injection of a contrast agent using FI resulted in a high salvage rate of studies and changed the initial diagnosis in a significant number of patients.  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