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   1174篇
  免费   70篇
  国内免费   37篇
耳鼻咽喉   16篇
儿科学   51篇
妇产科学   30篇
基础医学   120篇
口腔科学   32篇
临床医学   151篇
内科学   184篇
皮肤病学   14篇
神经病学   90篇
特种医学   38篇
外科学   376篇
综合类   21篇
预防医学   66篇
药学   42篇
中国医学   1篇
肿瘤学   49篇
  2023年   3篇
  2022年   13篇
  2021年   14篇
  2020年   14篇
  2019年   21篇
  2018年   33篇
  2017年   20篇
  2016年   18篇
  2015年   30篇
  2014年   60篇
  2013年   65篇
  2012年   75篇
  2011年   60篇
  2010年   35篇
  2009年   47篇
  2008年   44篇
  2007年   63篇
  2006年   53篇
  2005年   74篇
  2004年   38篇
  2003年   39篇
  2002年   56篇
  2001年   32篇
  2000年   40篇
  1999年   33篇
  1998年   26篇
  1997年   24篇
  1996年   27篇
  1995年   18篇
  1994年   16篇
  1993年   7篇
  1992年   17篇
  1991年   15篇
  1990年   16篇
  1989年   12篇
  1988年   11篇
  1987年   9篇
  1986年   15篇
  1985年   14篇
  1984年   6篇
  1983年   8篇
  1982年   4篇
  1981年   5篇
  1979年   4篇
  1978年   9篇
  1977年   5篇
  1976年   8篇
  1975年   6篇
  1962年   5篇
  1944年   2篇
排序方式: 共有1281条查询结果,搜索用时 15 毫秒
91.
We examined the associations between sedentary older veterans, those regularly involved in an outpatient exercise program and physical function. Sedentary and currently exercising older veterans performed a 30 s chair-stand test and 6 min walk test as part of an exercise program. Test results were then compared to national norms. The exercisers' test scores were not significantly different from the national averages. However, their mean 6 min walk score approached being significantly better than the national average (p = 0.095). The sedentary group's scores were significantly lower (p < or = 0.05) than the exercisers' scores and the national averages for both tests. In this cohort, older veterans who maintain a regular program of physical activity function at a level considered average or slightly above average compared to their age-matched peers, while sedentary veterans are significantly below average. Healthcare providers need to stress the importance of regular exercise to their older veteran patients.  相似文献   
92.
OBJECTIVE: To examine the longitudinal diagnostic efficiency of the DSM-IV criteria for obsessive-compulsive personality disorder (OCPD). METHOD: At baseline, criteria and diagnoses were determined using diagnostic interviews, and blinded assessments were performed 24 months later with 550 participants. Diagnostic efficiency indices (conditional probabilities, total predictive power, and kappa) were calculated for each criterion determined at baseline, using the independent OCPD diagnosis at follow-up as the standard. RESULTS: Longitudinal diagnostic efficiencies for the OCPD criteria varied; findings suggested the overall predictive utility of 'preoccupied with details', 'rigid and stubborn', and 'reluctant to delegate'. CONCLUSION: These findings suggest the predictive validity of three cognitive-interpersonal OCPD criteria.  相似文献   
93.
In vitro fertilization is a risk factor for vasa previa   总被引:2,自引:0,他引:2  
  相似文献   
94.
95.
A retrospective analysis of charts identified cases of superior mesenteric artery (SMA) syndrome occurring after scoliosis surgery over a 23-year period. Despite numerous reports on this potentially fatal complication of scoliosis surgery, no method exists to stratify patients for risk of developing disease after spine surgery. A study of charts was performed to identify all cases of SMA syndrome occurring after scoliosis surgery from 1972 to 1995. An upper gastrointestinal study with findings specific for the syndrome was requisite for inclusion. Patients' weight and height at the time of diagnosis of SMA syndrome were recorded. Based on standard national data tables, a percentile for weight, percentile for height, and a weight percentile for height were derived for each patient. The syndrome occurred after posterior spinal fusion in six patients (three boys, three girls). The average weight percentile for height, available in five of the six patients, was 3%, significantly different from both age-matched controls in the general population and from age-matched controls undergoing posterior spinal fusion for adolescent idiopathic scoliosis. This study, the largest reported from a single institution, suggests that a weight percentile for height of 5% is the degree of asthenia that allows compromise of the duodenum. The percentile identifies patients at risk for SMA syndrome for the purposes of increasing postoperative vigilance for gastrointestinal complaints, decreasing the threshold for diagnostic workup, and guiding perioperative dietary supplementation.  相似文献   
96.
A logit model is used to estimate provider choice from six types by malaria patients in rural Nepal. Patient characteristics that influence choice include travel costs, income category, household size, gender, and severity of malaria. Income effects are introduced by assuming the marginal utility of money is a step function of expenditures on the numeraire. This method of incorporating income effects is ideally suited for situations when exact income data is not available. Significant provider characteristics include wait time for treatment and wait time for laboratory results. Household willingness to pay (wtp) is estimated for increasing the number of providers and for providing more sites with blood testing capabilities. Wtp estimates vary significantly across households and allow one to assess how much different households would benefit or lose under different government proposals.  相似文献   
97.
PURPOSE: We explored the accuracy and bias of prediction equations (ACSM and Foster) in older, deconditioned men and women. We also examined the predictors of VO2(max) to further understand which variables affect respiratory fitness in the elderly. METHODS: One hundred seventy-one community dwelling, men (72.6 +/- 4.8 yr) and women (71.0 +/- 5.1 yr) screened in a clinical trial were retrospectively examined. VO2(max) was measured using a standardized protocol with gas exchange measured. Measured VO2 (max) values were compared with prediction equations via mean difference analyses, and bias was explored using Bland-Altman analyses. Regression analysis determined significant predictors of measured VO2 (max). Alpha was P相似文献   
98.
99.
100.
OBJECTIVE: Adenosine is released during myocardial ischaemia and delays atrioventricular nodal (AV) conduction. We hypothesized that free radicals present during reperfusion potentiate the negative dromotropic effect of adenosine on the AV node. METHODS AND RESULTS: Guinea pig hearts were prepared using the Langendorff technique, paced (200 beats/min), and instrumented to measure the atrium-to-His bundle (A-H) interval, an index of AV nodal conduction time. Adenosine (2 microM) prolonged the A-H interval by 5.7 +/- 0.5 ms from a control value of 35.7 +/- 1.3 ms. (n = 10, P < 0.05). In the absence of adenosine, the superoxide (O2-) generator pyrogallol (20 microM) did not affect the A-H interval (0.7 +/- 0.2 ms prolongation, n = 10). However, concurrent infusion of adenosine (2 microM) and pyrogallol (20 microM) lengthened the A-H interval by 11.0 +/- 0.8 ms from control (n = 10, P < 0.001). This A-H interval prolongation was reversed by cyclopentyl-1,3-dipropylxanthine (100 nM), a selective A1-adenosine receptor antagonist (P<0.001, n = 5). Similarly, A-H interval prolongation was decreased to 4.3 +/- 0.4 ms when NG-methyl-L-arginine (100 microM), a nitric oxide (NO) synthase inhibitor, was infused (n = 4). The superoxide scavenger superoxide dismutase (200 U/ml) also diminished the A-H interval prolongation to 7.1 +/- 0.6 ms (n = 4, P < 0.001). Ba2+ ( 100 microM), a blocker of the adenosine-induced inward potassium current (I(K,ADO)), did not significantly affect this potentiation (13.0 +/- 0.8 and 10.8 +/- 0.7 ms greater than control A-H interval in the absence and presence of Ba2+, respectively, n = 4). CONCLUSIONS: Superoxides and adenosine delay AV nodal conduction in a synergistic manner via a NO-dependent mechanism involving an I(K,ADO)-independent component. This phenomenon may contribute to the genesis of reperfusion arrhythmias.  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