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   23472篇
  免费   1472篇
  国内免费   227篇
耳鼻咽喉   401篇
儿科学   325篇
妇产科学   300篇
基础医学   3946篇
口腔科学   397篇
临床医学   1964篇
内科学   4591篇
皮肤病学   755篇
神经病学   1973篇
特种医学   1230篇
外国民族医学   1篇
外科学   3107篇
综合类   252篇
一般理论   4篇
预防医学   888篇
眼科学   492篇
药学   2192篇
中国医学   318篇
肿瘤学   2035篇
  2024年   23篇
  2023年   209篇
  2022年   532篇
  2021年   872篇
  2020年   444篇
  2019年   615篇
  2018年   712篇
  2017年   548篇
  2016年   809篇
  2015年   1048篇
  2014年   1189篇
  2013年   1414篇
  2012年   2067篇
  2011年   1972篇
  2010年   1145篇
  2009年   942篇
  2008年   1432篇
  2007年   1317篇
  2006年   1252篇
  2005年   1128篇
  2004年   978篇
  2003年   855篇
  2002年   746篇
  2001年   438篇
  2000年   423篇
  1999年   362篇
  1998年   171篇
  1997年   136篇
  1996年   125篇
  1995年   110篇
  1994年   90篇
  1993年   70篇
  1992年   108篇
  1991年   102篇
  1990年   89篇
  1989年   76篇
  1988年   79篇
  1987年   71篇
  1986年   58篇
  1985年   53篇
  1984年   39篇
  1983年   41篇
  1982年   26篇
  1981年   19篇
  1980年   24篇
  1979年   38篇
  1978年   19篇
  1976年   16篇
  1972年   15篇
  1969年   15篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
The relation between smoking and risk of asthma has been well-examined; however little attention has been paid to the correlation between smoking and asthma symptoms. The aims of this study were to examine respiratory symptoms in asthmatics with a highly prevalent use of inhaled corticosteroid (ICS) and to assess the effects of smoking and its cessation. A cross-sectional study of pulmonologist-based 3197 asthmatics (men 45.2%, ages 20-97) was performed using a questionnaire about smoking habits, the incidence and frequency of symptoms (sputum, cough and wheezing, night symptoms, and shortness of breath), physical activity interference, and medication. Although 81.4% of the patients used ICS according to the international guideline, 14.9% had activity interference, and daily symptoms remained in 43.3%. At the time of the questionnaire, 21.6% were current and 25.1% were ex-smokers. In multiple logistic regression analysis, the factors of significance (p < 0.0001) were (1) smoking; for all four symptoms, (2) age and duration of asthma; for shortness of breath. Current smokers were at a risk of sputum (age-adjusted odds ratio 2.32 [95% confidence interval 1.73-3.11]; 2.09 [1.57-2.79]), of cough and wheezing (2.38 [1.81-3.14]; 1.78 [1.35-2.36]), of night symptoms (1.95 [1.41-2.60]; 1.47 [1.09-1.98]), and of shortness of breath (1.70 [1.26-2.28]; 1.30 [0.97-1.75]) in men and women, respectively. These ratios in ex-smokers decreased to the level similar to nonsmokers. Although 81.4% of asthmatic patients used ICS, 43.3% complained of daily respiratory symptoms, especially sputum. It is suggested that the effects of ICS on asthma symptoms may be interfered with by smoking and therefore more emphasis should be placed on cessation of smoking.  相似文献   
22.
23.
24.
The azygos anterior cerebral artery, a rare anomaly in the circle of Willis in which only a single vessel supplies the medial aspects of both anterior cerebral hemispheres, is closely associated with saccular aneurysms. We present three cases of azygos anterior cerebral artery aneurysms among the 781 cerebral aneurysms surgically treated at our institution in an 11-year period. These three cases all involved elderly women who presented with subarachnoid hemorrhage. Conventional cerebral angiography and CT angiography revealed small saccular aneurysms at the distal ends of the azygos anterior cerebral arteries. These aneurysms were clipped successfully using a bifrontal interhemispheric approach. Hence, the pathogenesis of these particular aneurysms relating to hemodynamic change, associated anomalies, and surgical pitfalls is discussed with review of literature.  相似文献   
25.
The sperm penetration assay is an expensive, time-consuming test to assess male fertility in vitro. Although some investigators are enthusiastic in its application, others feel that it is not sensitive or specific enough to be used as part of the routine infertility evaluation. Indeed, this bioassay is not a faithful reproduction of in vivo conditions. However, if the SPA is abnormal, it is unlikely that sperm will fertilize a human ovum in vivo. Conversely, a normal SPA does not guarantee successful in vivo fertilization. No bioassay can be absolute in its predictive value, but false-negative results must be kept to a minimum for this bioassay to be of any clinical significance. Each laboratory performing the SPA should optimize the assay for sensitivity, reproducibility, and minimization of false-negative results and then establish normal and abnormal ranges of its own. If the limitations of the SPA are kept in mind, and if we employ it very selectively, it may still be useful.  相似文献   
26.
Tuberculin-sensitized guinea pigs were intravenously injected with heat-killed Propionibacterium acnes followed by an intravenous injection of purified protein derivatives 7 day later, resulting in the induction of intrahepatic cholestasis. Using this experimental model, the following results were obtained: (1) Both uptake and release of bile acid were inhibited in the hepatocytes prepared from the cholestasis guinea pigs. (2) The results of the erythritol clearance method indicated that the decrease in bile flow observed in the cholestasis guinea pigs was mostly attributable to the reduced bile excretion from the canaliculi. (3) The decrease in the formation of bile acid independent bile flow was the cause of the decrease in bile flow observed in the cholestasis guinea pigs. (4) There was no change in the permeability of the interhepatocellular tight junction in the cholestasis guinea pigs.  相似文献   
27.
28.
OBJECTIVE: To evaluate the ultrasonographic measurement of shoulder subluxation in patients with post-stroke hemiplegia. DESIGN: Prospective, single blind study. PATIENTS: A total of 41 patients with post-stroke hemiplegia were included (24 men and 17 women, mean age 56 years (standard deviation 11), age range 34-78 years). METHODS: Clinical evaluation of the affected shoulder was assessed using the Motricity Index scores and the Modified Ashworth Scale. Two ultrasonographic measurements were taken to check intra-rater reliability. The shoulder subluxation ratio was determined as the ratio of the radiographic vertical and horizontal distance, and the ultrasonographic lateral and anterior distances in the affected shoulder divided by that in the unaffected shoulder. RESULTS: Intraclass correlation coefficients of the repeated ultrasonographic lateral/anterior distance measurements in the unaffected and affected shoulders were 0.979/0.969 and 0.950/0.947, respectively. Ultrasonographic lateral/anterior distance ratios were negatively correlated with Motricity Index scores of the affected shoulder abduction (r = -0.490, p < 0.001/ r = -0.671, p < 0.001). Ultrasonographic anterior distance ratio was negatively correlated with Modified Ashworth Scale score of the affected shoulder (r = -0.374, p < 0.05). However, there was no correlation between radiographic distance ratios and clinical evaluation scores. CONCLUSION: We strongly recommend ultrasonography as a diagnostic tool to measure the degree of shoulder subluxation in patients with post-stroke hemiplegia.  相似文献   
29.
A 60-year-old Japanese man was hospitalized because of urinary leakage from the anus on October 3, 1994. Retrograde urethrography detected a fistula between the bulbous urethra and the rectum. Urethrocystoscopy revealed a tumor on the urethrorectal fistula. Tumor biopsy showed a well differentiated adenocarcinoma. Cystourethrectomy with fistulectomy, and ileal conduit urinary diversion were performed. Pathological examination revealed primary adenocarcinoma in the fistula with invasion to the prostatic urethra and bladder wall. The patient showed no evidence of a recurrence as of August, 1996.  相似文献   
30.
Multiple aortic aneurysms in Behçet’s disease were repaired with transluminaly placed endovascular stent grafts. Before deploying the stent graft device for permanent implantation for the saccular aneurysm located in the descending thoracic arota, from which feeding arteries for the spinal cord possibly branched, a retrievable stent graft was inserted and evoked spinal cord potential (ESP) were monitored in order to predict spinal cord ischemia. The original retrievable stent graft, constructed of a self-expandable Z-shaped stainless steel stent covered with e-PTFE, can be easily withdrawn into a 18 Fr. sheath after deployment. Blood flow into intercostal arteries branching from that part of the descending aorta where the permanent stent graft is planned to be implanted, is intercepted by the retrievable stent graft. A change of ESP during the temporary implantation of the device indicates that spinal cord ischemia would be caused by permanent implantation of the stent graft. In this case, no change of ESP was observed and the patient showed no postoperative paraplegia.The retrievable stent graft was useful for prediction of spinal cord ischemia before endoluminal stent graft repair of the descending aortic aneurysm. However, the device is not flexible enough to fit a severely tortuous aorta, therefore we are obliged to select patients to some extent. Further improvement of the device is required to make prediction of spinal cord ischemia with the retrievable stent graft possible in all cases.  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