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   80148篇
  免费   3625篇
  国内免费   330篇
耳鼻咽喉   1042篇
儿科学   2153篇
妇产科学   1994篇
基础医学   10557篇
口腔科学   2958篇
临床医学   5811篇
内科学   19698篇
皮肤病学   1647篇
神经病学   6819篇
特种医学   2441篇
外国民族医学   6篇
外科学   9422篇
综合类   425篇
一般理论   28篇
预防医学   8416篇
眼科学   1305篇
药学   5340篇
中国医学   303篇
肿瘤学   3738篇
  2023年   541篇
  2022年   1007篇
  2021年   2193篇
  2020年   1173篇
  2019年   1876篇
  2018年   3918篇
  2017年   2399篇
  2016年   1791篇
  2015年   1895篇
  2014年   2612篇
  2013年   3469篇
  2012年   5312篇
  2011年   5666篇
  2010年   3056篇
  2009年   2550篇
  2008年   4563篇
  2007年   4711篇
  2006年   4344篇
  2005年   4358篇
  2004年   3958篇
  2003年   3706篇
  2002年   3467篇
  2001年   1836篇
  2000年   1949篇
  1999年   1588篇
  1998年   585篇
  1997年   385篇
  1996年   375篇
  1995年   322篇
  1994年   270篇
  1993年   276篇
  1992年   800篇
  1991年   637篇
  1990年   613篇
  1989年   527篇
  1988年   472篇
  1987年   488篇
  1986年   424篇
  1985年   374篇
  1984年   273篇
  1983年   235篇
  1979年   200篇
  1978年   175篇
  1977年   149篇
  1975年   180篇
  1974年   181篇
  1973年   169篇
  1972年   168篇
  1971年   163篇
  1968年   150篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
21.
22.
INTRODUCTION: Ischemic heart disease is a major cause of heart failure in western societies. However, the factors that may influence left ventricular function (LVF) recovery after an acute coronary syndrome (ACS) are still unclear. OBJECTIVE: To identify variables that may influence LVF evolution one year after ACS. METHODS: 104 patients hospitalized with ACS between 7/1/2001 and 12/31/2002 and with systolic dysfunction--defined as an echocardiographic ejection fraction (EF) < or = 45%--were randomly allocated to a planned coronary follow-up program (FUP) or a general cardiology clinic (GC); patients from both groups were also randomly referred to a structured cardiac rehabilitation program (CRP). EF was re-assessed at one year. We compared differences between patients who recovered left ventricular function (EF > 45%; group 1) and those who did not (group 2). RESULTS: One year after discharge, 44.2% of the patients had recovered function. There were no significant differences between the groups in gender (77.7 vs. 76.5% male), age (56 vs. 59 years), hypertension, diabetes, dyslipidemia, smoking habits or family history. A previous history of cardiovascular events was more frequent in group 2 (11.1% vs. 35.3%, p = 0.03). Cardiac catheterization was performed before discharge in 88.8% and 88.2% in groups 1 and 2 respectively (p = NS); no differences were found in coronary anatomy between the two groups. Angioplasty was performed in 54.2% in group 1 and 50% in group 2 (p = NS). There were no differences in the use of angiotensin-converting enzyme inhibitors (83.3% vs. 87.5%), beta-blockers (87.5% vs. 87.5%), nitrates (37.5% vs. 33.3%), aspirin (95.8% vs. 95.8%), statins (79.1% vs. 75%) or diuretics (20.8% vs. 45.8%). There was no significant difference in LVF recovery between patients randomized to FUP or GC (38.5% vs. 54.5%). 87.5% of patients who completed the CRP had normal EF at one year compared to 32.7% of patients not referred to the program (p = 0.009). Although EF improved in both groups, this improvement was greater in patients who completed a CRP (EF 8% vs. 5%, p = 0.003). CONCLUSION: A previous cardiovascular event and completion of a CRP were the only variables that influenced LVF recovery. Thus, enrollment in a CRP, in addition to standard therapy, could be an important therapeutic measure in patients with systolic dysfunction after ACS; our data suggest that these programs should be more widely used.  相似文献   
23.
The aim of this study in pigs was to investigate the local pharmacokinetics of fexofenadine in the intestine and liver by using the pig as a model for drug transport in the entero-hepatobiliary system. A parallel group design included seven pigs (10-12 weeks, 22.2-29.5 kg) in three groups (G1, G2, G3), and a jejunal single-pass perfusion combined with sampling from the bile duct and the portal, hepatic, and superior caval veins was performed. Fexofenadine was perfused through the jejunal segment alone (G1: 120 mg/l, total dose 24 mg) or with two different verapamil doses (G2: 175 mg/l, total dose 35 mg; and G3: 1000 mg/l, total dose 200 mg). The animals were fully anesthetized and monitored throughout the experiment. Fexofenadine had a low liver extraction (E(H); mean +/- S.E.M.), and the given doses of verapamil did not affect the E(H) (0.13 +/- 0.04, 0.16 +/- 0.03, and 0.12 +/- 0.02 for G1, G2, and G3, respectively) or biliary clearance. The E(H) for verapamil and antipyrine agreed well with human in vivo data. Verapamil did not increase the intestinal absorption of fexofenadine, even though the jejunal permeability of fexofenadine, verapamil, and antipyrine showed a tendency to increase in G2. This combined perfusion and hepatobiliary sampling method showed that verapamil did not affect the transport of fexofenadine in the intestine or liver. In this model the E(H) values for both verapamil and antipyrine were similar to the corresponding values in vivo in humans.  相似文献   
24.
Many types of seafood require cooking before ingestion and it has been demonstrated that this cooking process may affect the antigenicity and allergenicity of the food. We describe a case of anaphylaxis caused by selective sensitization to razor shell, a mollusc. In vivo and in vitro studies confirmed sensitization to boiled razor shell. Analysis of the nature of the allergen yielded results that were consistent with the findings of other authors and suggested that allergens involved in seafood allergy are commonly high molecular weight proteins that, in most cases, are heat stable.  相似文献   
25.
26.
Background  Coccygodynia can cause severe pain and disability in patients. There are contradictions in the literature regarding the final results of coccygectomy for coccygodynia. We evaluated the long-term effects of coccygectomy on the intensity, characteristics, and manifestation of pain caused by coccygodynia to determine the adequacy of operation among treatment modalities. Materials and methods  Thirty-four patients with coccygodynia were treated by coccygectomy. In 22 cases, trauma, and in one case childbirth was the cause. 11 cases were regarded as idiopathic. The intensity, characteristics of pain, and the most painful activities were evaluated at an average of 7.6 (3–18) years of follow-up time. Results  Before the operation, all 34 patients had pain while sitting, moreover, 26 of them had pain during standing, walking, at night or a combination of these. 21 patients had intolerable or very intensive, mainly acute, sharp or burning pain. 11 patients had dyschesia, 2 had dysuria and 6 had dyspareunia. At follow-up, 7 patients were completely free of pain, 15 others had moderate, 11 medium, and only one patient had severe, but none had intolerable pain. Only seven patients had acute, sharp or burning pain postoperatively. The decrease of average pain score from 8.0 to 3.2 was significant (P < 10−12). The number of the patients with dyschesia and dyspareunia decreased from 11 to 7 and from 6 to 3, respectively. Two patients had dysuria, but their complaints did not change after the operation. One of the two patients who needed reoperation had an excellent final result, while the other remained unchanged. 12 and 16 patients (together 82%) regarded the final result of the operation excellent and good, respectively. The condition of five others did not change, while one became worse. The patients with younger age, smaller body mass index, and less co-morbidities had better final result. There were no serious complications. Conclusion  Coccygectomy for coccygodynia is a safe method to decrease the intensity of pain and other complaints of the patients. The operation can be the choice of treatment if conservative measures fail.  相似文献   
27.
28.
29.
The impact of continuous positive airway pressure (CPAP) treatment on the airway responsiveness of asthmatic subjects with obstructive sleep apnoea (OSA) has scarcely been studied. A prospective study was performed comparing the changes in airway responsiveness and quality of life in stable asthmatic OSA patients, before and 6 weeks after their nocturnal CPAP treatment. A total of 20 subjects (11 males and nine females) participated in the study. With the nocturnal CPAP treatment, the apnoea/hypopnoea index dropped from 48.1 +/- 23.6 x h(-1) to 2.6 +/- 2.5 x h(-1). There were no significant changes in airway responsiveness after CPAP treatment (provocative concentration causing a 20% fall in forced expiratory volume in one second (FEV(1); PC(20) 2.5 mg x mL(-1) (1.4-4.5)) compared with baseline (PC(20) 2.2 mg x mL(-1) (1.3-3.5)). There was no significant change in FEV(1) either. However, the asthma quality of life of the subjects improved from 5.0 +/- 1.2 at baseline to 5.8 +/- 0.9 at the end of the study. In conclusion, nocturnal continuous positive airway pressure treatment did not alter airway responsiveness or forced expiratory volume in one second in subjects with stable mild-to-moderate asthma and newly diagnosed obstructive sleep apnoea. However, nocturnal continuous positive airway pressure treatment did improve asthma quality of life.  相似文献   
30.
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