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   22682篇
  免费   1927篇
  国内免费   41篇
耳鼻咽喉   254篇
儿科学   731篇
妇产科学   412篇
基础医学   3164篇
口腔科学   341篇
临床医学   2429篇
内科学   4638篇
皮肤病学   404篇
神经病学   1934篇
特种医学   664篇
外国民族医学   3篇
外科学   2887篇
综合类   483篇
一般理论   15篇
预防医学   2327篇
眼科学   732篇
药学   1638篇
中国医学   22篇
肿瘤学   1572篇
  2022年   154篇
  2021年   332篇
  2020年   256篇
  2019年   377篇
  2018年   396篇
  2017年   299篇
  2016年   369篇
  2015年   431篇
  2014年   603篇
  2013年   868篇
  2012年   1297篇
  2011年   1383篇
  2010年   676篇
  2009年   700篇
  2008年   1156篇
  2007年   1294篇
  2006年   1242篇
  2005年   1259篇
  2004年   1221篇
  2003年   1055篇
  2002年   1059篇
  2001年   514篇
  2000年   557篇
  1999年   530篇
  1998年   312篇
  1997年   229篇
  1996年   241篇
  1995年   211篇
  1994年   183篇
  1993年   159篇
  1992年   340篇
  1991年   333篇
  1990年   323篇
  1989年   316篇
  1988年   294篇
  1987年   265篇
  1986年   303篇
  1985年   261篇
  1984年   227篇
  1983年   184篇
  1982年   174篇
  1981年   133篇
  1980年   131篇
  1979年   210篇
  1978年   151篇
  1977年   114篇
  1976年   108篇
  1974年   122篇
  1973年   140篇
  1972年   103篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
Postoperative pain control can be unsatisfactory for a variety of reasons, including patients' attitudes towards pain treatment itself. To assess patients' expectations and their influence on postoperative analgesia, as well as the prevalence of pain following common gynaecological surgery, a prospective study was performed in 166 patients with either adbominal hysterectomy, mastectomy, laparoscopy or uterine curettage. After a first postoperative period with routine on-demand analgesia, a nurse specialised in pain treatment discussed the purposes and risks of pain treatment with the patients and cared for these patients in the second, subsequent study period. Following this discussion, 30 of 40 patients refusing analgesics in the first study period agreed to be given pain medication. In the groups with hysterectomy or mastectomy, pain control improved in the second postoperative period, even though the doses of analgesics administered were generally lower. Education of patients regarding the aims and risks of pain therapy is an essential part of pain control and can lead to an improvement of postoperative analgesia.  相似文献   
42.
43.
44.
45.
Summary Partial anomalous pulmonary venous connections (PAPVCs) are rare in association with an intact atrial septum. However, the diagnosis should be considered in patients with otherwise unexplained findings of left-to-right shunt and right heart enlargement. An unusual variant is presented, which we considered unsuitable for operative repair, based on findings at catheterization. Developmental, hemodynamic, and surgical considerations are discussed.  相似文献   
46.
The accuracy and precision of the Finapres in recording rest and exercise blood pressure compared with the intra-arterial (aortic and brachial) and random-zero sphygmomanometer methods was assessed in 84 ischaemic patients in three different studies. Firstly, comparison at rest with the aortic intraarterial pressure in 50 ischaemic patients demonstrated that the Finapres systolic (136.5 ± 21.1 vs. 129.3 ± 19.0 mmHg;p < 0.001) and mean (92.4 ± 13.4 vs. 90.7 ± 11.4 mmHg;p < 0.001) arterial pressures were higher and diastolic pressures lower (70.4 ± 11.5 vs. 71.5 ± 9.8 mmHg;p < 0.001). The reproducibility of the Finapres and invasive method was similar for systolic (4.6% vs. 4.0%), diastolic (2.8% vs. 2.7%) and mean (3.3% vs. 3.0%) blood pressures. Second, in seven subjects studied twice at rest and during 4 min supine bicycle exercise, the exercise increase in blood pressure was greater on the Finapres compared with the brachial intra-arterial pressure (systolic +10.2 ± 6.3 vs. +3.6 ± 9.8 mmHg; diastolic +9.6 ± 11.1 vs. +0.2 ± 2.1 mmHg;p = 0.02 for each); however, at steady-state the peak/trough differences in pressure between the methods were similar. Thirdly, compared under rest conditions, to random zero sphygmomanometer (RZO), the Finapres systolic pressure was higher (6.8 ± 3.5 mmHg) and diastolic pressure lower (–6.0 ± 1.9 mmHg). During upright bicycle exercise, the difference between the Finapres and RZO in systolic blood pressure increased at each level of exercise (+14.3 ± 4.2, +17.9 ± 4.0 and +22.2 ± 4.1 mmHg respectively at each exercise stage:p < 0.01). For RZO, diastolic blood pressure fell as exercise workload increased whereas Finapres diastolic blood pressure increased on exercise (3.1 ± 2.6, 7.0 ± 2.1 and 8.1 ± 2.0 mmHg respectively:p < 0.01). Thus there were systematic differences between the values recorded by the Finapres and proximal blood pressure methods and limited agreement in the rest to exercise increments related to light exercise. Calibration of the Finapres values in terms of the other methods is limited by the variable relationship to these related changes in arterial distensibility.  相似文献   
47.
Summary We enrolled children with acute lymphoblastic leukemia (ALL) in a Pediatric Oncology Group (POG) pilot study to monitor erythrocyte (RBC) methotrexate (MTX) and folate (F) levels before and during treatment. The mean value for RBCF at diagnosis was 0.86±0.46 nmol/ml RBC in the 214 patients who achieved remission and 1.21±0.74 nmol/ml RBC in the 10 patients who did not (P=0.020). Folate levels tended to increase during remission induction, but they dropped following an intensive consolidation with methotrexate to levels that were sustained throughout chemotherapy treatment. Methotrexate levels reached mean values of approximately 0.15 nmol/ml RBC at the end of an intensive methotrexate consolidation, then fell to levels that were sustained throughout maintenance therapy. There was a weak correlation between improved event-free survival and higher RBCMTX levels after consolidation, but no correlation was found between improved survival and the level of RBCMTX or RBCF during maintenance therapy. A larger study with more complete data is needed to determine whether RBCMTX or RBCF might be useful in predicting event-free survival in patients with ALL.This work was supported in part by grants from the National Cancer Institute and the National Institute of Health (CA-30969, CA-28476, CA29139, CA-159-89, and CA-33587)  相似文献   
48.
Flow-independent angiography (FIA), an approach that isolates arterial blood using MR relaxation characteristics rather than flow effects, was evaluated for application in peripheral vascular disease (PVD). First, pilot studies were conducted in which FIA coronal projection images were obtained from controls and symptomatic patients with PVD to assess clinical utility. All control images corresponded to the expected leg arterial anatomy with little interference from deep veins (one of five) and muscle (zero of five). Superficial venous signal was less well suppressed in comparison to deep veins (four of five). Images of symptomatic patients were less consistent with difficulty suppressing muscle and deep venous signal in some cases and edema when present. We then compared T2 values for muscle (T2m, tibialis anterior), arterial blood (femoral and popliteal arteries), and venous blood (femoral, popliteal, and saphenous veins) in controls (n = 8) and symptomatic patients with intermittent claudication (n = 5) or ischemic rest pain (n = 7). Changes in T2 measurements of various tissues accounted for poorer contrast in symptomatic patients. Patients with ischemic rest pain had significantly higher T2m compared with controls (T2m = 39.3 ± 2.1 (1 standard error of the mean [SEM]) versus 30.9 ± .4, P < .01). For all measurements, other than saphenous vein, variances were greater in symptomatic patients. To realize the inherent advantages of FIA for this clinical application, additional work on suppression of signals from muscle, veins, and edema is required. One promising approach involves shifting from projection images to three-dimensional acquisitions for improved tissue suppression.  相似文献   
49.
Eighty-two women with complaints of moderate to severe premenstrual symptoms were recruited for a double-blind, controlled trial of a triphasic oral contraceptive (o.c.). Subjects made daily ratings of symptoms for at least one baseline cycle and were then randomly assigned to receive either placebo or o.c. for three months. Twenty-three women dropped out of the study (18 o.c., 5 placebo), 13 failed to show prospective confirmation of moderate to severe premenstrual symptoms, and one placebo subject had an anovulatory cycle. Forty-five women with prospectively-confirmed premenstrual changes (20 o.c., 25 placebo) completed the study. Premenstrual breast pain and bloating were significantly reduced with active treatment compared to placebo (p less than 0.03) but there were no beneficial effects of the o.c. over placebo for any of the mood symptoms. Women who received o.c.s reported decreased sexual interest after starting treatment and this effect was independent of any adverse influence on mood.  相似文献   
50.
The development of implantable left ventricular assist devices (LVADs) has almost reached the stage of providing permanent circulatory support in patients who are unsuitable for, or denied, the transplant option. As part of our ongoing haemodynamic evaluation of the Thermo Cardiosystems Inc. (Boston, USA) Mark 14 pneumatic LVAD, pressure-volume loops have been produced from in vitro studies using a modified National Heart Lung and Blood Institute (NHLBI, USA) mock circulatory loop. These studies have demonstrated that during certain phases of the pump cycle non-physiologically high and low pressures are generated within the LVAD. Such abnormal pressures may damage either the bioprosthetic valves in the LVAD or the native heart, and may have adverse effects on cardiovascular control mechanisms.  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