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   66182篇
  免费   3897篇
  国内免费   1270篇
耳鼻咽喉   466篇
儿科学   1414篇
妇产科学   653篇
基础医学   5943篇
口腔科学   552篇
临床医学   9792篇
内科学   10972篇
皮肤病学   314篇
神经病学   3333篇
特种医学   1948篇
外国民族医学   2篇
外科学   7408篇
综合类   10526篇
现状与发展   3篇
一般理论   1篇
预防医学   5115篇
眼科学   2594篇
药学   6895篇
  36篇
中国医学   2841篇
肿瘤学   541篇
  2024年   98篇
  2023年   907篇
  2022年   1606篇
  2021年   2562篇
  2020年   2301篇
  2019年   1890篇
  2018年   1941篇
  2017年   1884篇
  2016年   1987篇
  2015年   1950篇
  2014年   4281篇
  2013年   4665篇
  2012年   3684篇
  2011年   4079篇
  2010年   3088篇
  2009年   3014篇
  2008年   3027篇
  2007年   3036篇
  2006年   2794篇
  2005年   2303篇
  2004年   2012篇
  2003年   1696篇
  2002年   1474篇
  2001年   1362篇
  2000年   1231篇
  1999年   1060篇
  1998年   896篇
  1997年   936篇
  1996年   779篇
  1995年   828篇
  1994年   742篇
  1993年   633篇
  1992年   627篇
  1991年   558篇
  1990年   517篇
  1989年   452篇
  1988年   469篇
  1987年   414篇
  1986年   369篇
  1985年   429篇
  1984年   457篇
  1983年   264篇
  1982年   364篇
  1981年   288篇
  1980年   266篇
  1979年   229篇
  1978年   203篇
  1977年   142篇
  1976年   116篇
  1973年   101篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
目的探讨老年原发性高血压(ET)患者脉压与急性心肌梗塞(AMI)的关系。方法观测45例老年高血压病合并急性心肌梗塞患者的收缩压(SBP)、舒张压(DBP)及脉压(PP),以31例老年单纯高血压患者(冠脉造影排除冠心病)作对照组,进行比较。结果并发急性心肌梗塞组,其脉压较单纯高血压组明显增高。结论脉压与老年人急性心肌梗塞密切相关,对老年人高血压的治疗更要注重控制脉压。  相似文献   
72.
4132名少年儿童血压状况调查分析   总被引:5,自引:0,他引:5  
目的了解7~14岁少年儿童血压特点,为流行病学及预防成人高血压提供参考数据。方法用统一标准采集血压及有关数据,用概率单位法行正态性检验,确定血压95%参考值范围,对年龄与血压和体质指数进行相关性分析,行U检验、t检验。结果随年龄增大血压也逐渐上升,各年龄段男女之间血压差异无统计学意义。体质指数随年龄增大而增加。血压偏高者其体质指数高于同年龄段中值水平。结论年龄与血压和体质指数呈正相关。血压偏高者体质指数都具有较高中值水平。  相似文献   
73.
目的 应用超声多普勒技术测量正常婴儿肺动脉主干及左右肺动脉血流速度,并初步探讨其可能的机理.方法 使用GE Vivid7超声诊断仪检查60例正常新生儿,分别检测1周、1个月、6个月及1年时主动脉内径AOD;肺动脉主干内径MPA及血流速度Pv,左、右肺动脉内径LPA、RPA及血流速度LPv、RPv,并计算LPA RPA/AO.结果 1周时左、右肺动脉速度高于肺动脉主干速度,且以右肺动脉明显,1周后左、右肺动脉血流速度逐渐减慢,1年后均基本低于肺动脉主干内血流速度,肺动脉主干血流速度及LPA RPA/AO比例在1周、1个月、6个月及1年组差异无统计学意义.结论 正常新生儿左、右肺动脉血流速度较高,随生长、发育肺动脉血流速度逐渐降低直至正常.  相似文献   
74.
Purpose: To assess the accuracy of intraarterial measurement of transstenotic pressure gradients for the detection of hemodynamically suboptimal iliac angioplasty. Methods: In 14 patients, referred for diagnostic angiography, mean pressure gradients in the aorta and iliac artery were obtained twice, using a double-sensor pressure catheter. Additional iliac measurements were performed during pharmacologically induced flow augmentation. Repeatability was assessed by calculation of the mean difference plus standard deviation (MD ± SD) and repeatability coefficient (2 × SD). These results were extrapolated to 137 iliac angioplasty procedures with secondary stenting where there was a residual pressure gradient > 10 mmHg. Results: MD ± SD for repeated measurements at rest and during flow augmentation were 0 ± 2 mmHg and 1 ± 3 mmHg, respectively. Repeatability coefficients were 3 and 6 mmHg. Mean pressure gradients after hemodynamically insufficient angioplasty were 8 ± 7 mmHg at rest and 17 ± 5 mmHg following vasodilatation. Inaccurate pressure recordings may have led to inappropriate stent placement in less than 2.5%, and inappropriate denial of stent placement in less than 5% of the lesions. Conclusion: Variability of intraarterial pressure measurements has little consequence in the detection of hemodynamically significant stenosis after angioplasty. Received: 0/00/00/Accepted: 0/00/00  相似文献   
75.
Oxygen-sensitive F-19 magnetic resonance imaging of perfluorocarbon compounds requires that fluorocarbon T1 changes correlate with the local Po2 and not with the composition of the surrounding aqueous phase. The influence of various bioconstituents and paramagnetic ions within the aqueous phase on the F-19 fluorocarbon phase T1 for PFC emulsions was evaluated at 0.14 and 0.66 T. T1 was measured for FC-43, perflubron, and a fluorinated surfactant. Controlled variables introduced in the aqueous phase included annex solution constituents, blood, pH changes, and Gd-DTPA. For a constant Po2, the F-19 T1s were independent of the emulsion constituents, blood concentration, and pH. For FC-43 and perflubron, F-19 T1 was independent of the Gd-DTPA concentration, while the aqueous phase T1 decreased by more than an order of magnitude. XMO-10 (smallest emulsion particle size) showed a slight decrease in F-19 T1 with increasing Gd-DTPA concentration at 0.66 T.  相似文献   
76.
1. The relationship between work-rate and the antihypertensive effect of exercise in hypertensives, and the mechanism of that effect, were investigated by a crossover clinical trial. 2. Ten mild hypertensives were randomly divided into two groups. One group performed low work-rate exercise (LWE) on a cycle ergometer for 10 weeks (blood lactate threshold; ~50% of maximum oxygen consumption [V?O2max]). After a 10 week interval without exercise training, these subjects were then switched to a high work-rate exercise (HWE) regimen (4 mmol/ L of blood lactate; ~75% of V?O2max) for another 10 weeks. In the other group, the order of exercise training was reversed. Since two patients withdrew from the protocol during HWE periods, statistical analysis was performed on the data from the remaining eight patients. There were no order effects observed in any of the data from the two groups. 3. During both LWE and HWE, resting blood pressure (BP) fell significantly after the initiation of exercise therapy (P<0.05). Furthermore, the overall effects of 10 weeks of LWE and HWE on BP were not significantly different. 4. The work-rate at the lactate threshold, which reflects physical fitness, had increased significantly by 16 W (P<0.01) after the LWE period and by 11 W (P<0.01) after the HWE. 5. During the LWE period, changes in haemodynamic and humoral variables were not significant, except for a reduction in plasma norepinephrine at week 10 (P<0.05). In the HWE period, changes in haemodynamic and humoral variables were not significant. 6. Based on these findings, LWE is recommended for mild hypertensives because of its safety.  相似文献   
77.
78.
Thirty women, 25 with incontinence and five asymptomatic volunteer control subjects, were evaluated urodynamically by a variety of techniques, including ultrasound cystourethrography. The ultrasound evaluation was found to be a helpful adjunct in diagnosis. In comparison with radiologic techniques it offers more safety, more comfort, more privacy, more viewing time, and less cost. Bladder and urethral morphology during voiding activity and the amount and direction of urethrovesical mobility are easily determined by utilizing ultrasound techniques.  相似文献   
79.
Data on 232 members of a single pedigree, descended from two pairs of original parents, were made available to the participants of Genetic Analysis Workshop 8 (GAW8). In addition to information concerning age and sex, measurements for 10 quantitative traits and genotypes at 22 polymorphic marker loci were also provided for a subset of 193 of these family members. © 1993 Wiley-Liss, Inc.  相似文献   
80.
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