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   41639篇
  免费   2484篇
  国内免费   871篇
耳鼻咽喉   353篇
儿科学   971篇
妇产科学   346篇
基础医学   3183篇
口腔科学   394篇
临床医学   6020篇
内科学   8254篇
皮肤病学   186篇
神经病学   2450篇
特种医学   1156篇
外国民族医学   2篇
外科学   5279篇
综合类   5828篇
现状与发展   3篇
预防医学   2485篇
眼科学   2514篇
药学   4262篇
  25篇
中国医学   1144篇
肿瘤学   139篇
  2024年   78篇
  2023年   694篇
  2022年   1205篇
  2021年   1701篇
  2020年   1531篇
  2019年   1335篇
  2018年   1385篇
  2017年   1261篇
  2016年   1267篇
  2015年   1214篇
  2014年   2610篇
  2013年   3013篇
  2012年   2100篇
  2011年   2413篇
  2010年   1785篇
  2009年   1803篇
  2008年   1918篇
  2007年   1910篇
  2006年   1714篇
  2005年   1425篇
  2004年   1248篇
  2003年   995篇
  2002年   892篇
  2001年   871篇
  2000年   688篇
  1999年   637篇
  1998年   563篇
  1997年   588篇
  1996年   483篇
  1995年   534篇
  1994年   471篇
  1993年   409篇
  1992年   422篇
  1991年   373篇
  1990年   347篇
  1989年   306篇
  1988年   317篇
  1987年   287篇
  1986年   265篇
  1985年   293篇
  1984年   298篇
  1983年   176篇
  1982年   241篇
  1981年   195篇
  1980年   171篇
  1979年   151篇
  1978年   130篇
  1977年   77篇
  1976年   66篇
  1975年   45篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Summary The aim of this study was to evaluate the level of physical capacity in a female hospital population of Paris and its suburbs. A total of 1505 women working in the selected departments filled in a questionnaire concerning their working conditions, life habits and health and also attended a medical examination. The effort test performed consisted in flexing the legs 20 times with the chest held straigt, in 40 s. The heart rates were measured for the first, the second and the third minutes of recovery (first 15 s multiplied by 4). The blood pressure was measured just after the heart rate, for the first and the third minute. Recovery indices have been constituted from the results. The respective weights of anthropometric and sociodemographic risk factors for recovery indices were studied in multiple logistic regression models. The classification enables us to consider about 25%–30% of our population as having a satisfactory physical capacity, about 26%–27% as having an acceptable capacit, and about 24%–27% as having a weak capacity. About 21% of the population presented an excessive pressure reaction and 44% a questionable pressure reaction. Our results concerning the level of physical capacity of the female nursing staff should be taken into account especially in the future planning of work loads and architectural choices, which must avoid excessive physical burdens in relation to this level. An improvement in the level of physical capacity could be envisaged as well.  相似文献   
102.
采用组化特染,透射电镜和图象分析仪观察了35只正常人眼筛板结缔组织的纤维成分和结构形态,根据生物力学原理分析了筛束的力学性质和筛板的结构特征,探讨了筛板的损害形式和在眼压与视神经损害间的中介作用及其影响因素。结果显示,筛束含有细胞间质所有三种纤维,具有弹性、塑性和刚性三重复合性质,筛板纵向椭圆、筛束行径和密度象限性差异及筛板厚度个体性差异等与筛板抗损害性能有关。眼压对筛板作用有两种途径,筛板损害是  相似文献   
103.
高血压病合并脑梗死的动态血压特点   总被引:4,自引:0,他引:4  
目的 :观察高血压病合并脑梗死患者的动态血压特点。方法 :对 70例高血压病合并脑梗死患者和 1 0 2例单纯高血压病患者进行 2 4h动态血压监测。结果 :84 %高血压病合并脑梗死患者血压昼夜节律消失 ,而单纯高血压病患者 5 8%消失 (P <0 .0 1 ) ;高血压病合并脑梗死组 85 %出现晨峰 ,而单纯高血压病组 5 5 %出现晨峰 (P <0 .0 1 )。结论 :血压的昼夜变化和晨峰与高血压病合并脑梗死密切相关。高血压病合并脑梗死患者晨峰明显增加 ,昼夜节律消失明显  相似文献   
104.
2%HPMC对兔眼内压及角膜内皮影响的实验研究   总被引:5,自引:0,他引:5  
杨惠英  窦宏亮 《眼科研究》1992,10(3):164-166
报导了2%羟丙基甲基纤维素(HPMC)、1%透明质酸钠(Na-HA)及平衡盐液(BSS)分别注入兔眼前房后,其眼内压、角膜内皮细胞数及内皮细胞形态的变化。证实自制2%HPMC 与进口1%Na-HA 性能基本相同,仅有一过性眼压升高,不损害角膜内皮,能在眼前节手术及人工晶体植入时有效地保护角膜内皮细胞。  相似文献   
105.
106.
The human foot is a complex mechanical structure consisting of bones, ligaments and joints. They act together to provide a robust system capable of absorbing and dissipating the intermitted pressure that is subjected to its plantar surface during walking to prevent soft tissue breakdown. Current studies suggest that plantar foot pressure may lead to soft tissue breakdown (e.g. neuropathic ulceration) and hence research has so far concentrated on investigating the mechanical effects of plantar foot pressure on the foot’s integrity. This has been possible through the widely available pressure and force platforms as well as in-shoe pressure systems. However, to understand how plantar foot pressure causes soft tissue breakdown it is vital to investigate both the physiological–mechanical interactions between the skin and plantar foot pressure. This review suggests that with the current advances in technology, the physiological response of skin blood flow to mechanical plantar foot pressure should be investigated and correlated further, both during static and dynamic loading, by developing a new system capable of either measuring both variables simultaneously or by synchronising two systems in real time.  相似文献   
107.
赵伟  任霖  张卫泽 《宁夏医学杂志》2004,26(11):701-702
目的 比较高血压合并阻塞性睡眠呼吸暂停患者的短期血压变异性。方法 将155例分为对照组、高血压组、高血压合并轻度或中重度阻塞性睡眠呼吸暂停组,EE较患者不同活动状态的短期血压变异性。结果 高血压合并中重度阻塞性睡眠呼吸暂停组患者睡眠期间和早晨血压变异系数分别为:收缩压18.69、21.32;舒张压19.41、23.61,明显高于其他各组。结论 夜间睡眠期间和早晨短期血压变异性增加,是高血压合并中重度阻塞性睡眠呼吸暂停患者夜间和早晨心血管事件发生率增加的重要危险因素。  相似文献   
108.
Our study aimed to investigate the cardiovascular autonomic regulation related to the wearing-off phenomenon in Parkinson's disease (PD). We measured blood pressure (BP) and heart rate (HR) at rest and during orthostatic test in 16 patients with PD with wearing-off and in 15 patients with PD without wearing-off both before (baseline) and repetitively at 1-h intervals for up to 4 h after the morning PD medication dose.
The patients with wearing-off had fluctuation of BP during the observation period, BP increasing when the motor performance worsened and vice versa. The mean supine BP was at its highest at the baseline measurement (patients with wearing-off, 145 ± 18 mmHg; patients without wearing-off, 138 ± 17 mmHg), fell during the first hour (patients with wearing-off, 119 ± 17 mmHg; patients without wearing-off, 126 ± 18 mmHg), and then rose again toward the end of the observation period (patients with wearing-off, 136 ± 15 mmHg; patients without wearing-off, 138 ± 18 mmHg). This BP change was statistically significant only in PD patients with wearing-off ( P  < 0.001).
In conclusion, BP seems to fluctuate with motor impairment in PD patients with wearing-off. This fluctuation may represent autonomic dysfunction caused by the PD process itself, the effect of PD medication, or both.  相似文献   
109.
This study was undertaken to determine the nature of pressure changes in manometric studies of renal pelvis and calyces. In previous studies in pigs it has been assumed that pressure increases occur in the contracting segments of the renal pelvis and calyces, but our observations suggested that these increases were actually due to distension of noncontracted segments. Pressures were recorded with two catheters introduced percutaneously into the pyelocalyceal system with simultaneous video recording of the fluoroscopic image. There was no pressure rise in the calyces or the renal pelvis when these segments contracted; however, pressure rose when the noncontracted calyces were distended by a remote contraction ring. These findings confirmed the observations at kinetic urography. They agreed with the hydrodynamic experience that the pressure in a ring-shaped contracted segment is lower than upstream and downstream of that segment. It was concluded that if the porcine pyelocalyceal system is a valid model of the human, the pressure increases, assumed to be contractions, were actually caused by the injection and distension of the noncontracted segments.  相似文献   
110.
应用计算机化清醒大鼠血流动力学测定技术,观察5-HT2受体阻滞剂Ritanserin(Rit)和α1受体阻滞剂哌唑嗪对清醒自发性高血压大鼠(SHR)的血压、血压波动性(BPV)和动脉压力感受性反射血压控制部分(ABR-BP)的效应,旨在初步探讨兼具5-HT2受体和α1受体阻滞作用地新型抗高血压药Ketanserin降低BPV的机制。结果表明:Rit对SHR无降压作用,但侧脑室给药明显提高ABR-B  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