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   3220篇
  免费   222篇
  国内免费   11篇
耳鼻咽喉   29篇
儿科学   48篇
妇产科学   33篇
基础医学   461篇
口腔科学   46篇
临床医学   320篇
内科学   809篇
皮肤病学   176篇
神经病学   304篇
特种医学   102篇
外科学   463篇
综合类   6篇
一般理论   3篇
预防医学   223篇
眼科学   61篇
药学   157篇
中国医学   2篇
肿瘤学   210篇
  2024年   3篇
  2023年   28篇
  2022年   31篇
  2021年   103篇
  2020年   55篇
  2019年   71篇
  2018年   95篇
  2017年   81篇
  2016年   76篇
  2015年   82篇
  2014年   132篇
  2013年   156篇
  2012年   246篇
  2011年   284篇
  2010年   149篇
  2009年   137篇
  2008年   219篇
  2007年   250篇
  2006年   192篇
  2005年   182篇
  2004年   177篇
  2003年   131篇
  2002年   125篇
  2001年   25篇
  2000年   19篇
  1999年   16篇
  1998年   32篇
  1997年   18篇
  1996年   31篇
  1995年   23篇
  1994年   15篇
  1993年   16篇
  1992年   14篇
  1991年   19篇
  1990年   22篇
  1989年   27篇
  1988年   20篇
  1987年   27篇
  1986年   29篇
  1985年   14篇
  1984年   15篇
  1983年   3篇
  1982年   11篇
  1981年   5篇
  1980年   5篇
  1979年   8篇
  1978年   3篇
  1976年   9篇
  1974年   6篇
  1973年   3篇
排序方式: 共有3453条查询结果,搜索用时 15 毫秒
961.
962.
OBJECTIVE: To compare the postprocedural and long-term clinical outcomes of two groups of patients, all presenting with chronic saphenous vein graft (SVG) occlusion, who underwent either SVG or native vessel reopening. BACKGROUND: Chronic total occlusions (CTO) treatment in patients who underwent previous surgical revascularization is a dilemma and the choice of performing native vessel or SVG recanalization is not always easy. METHODS: Between July 2002 and October 2004, a total of 260 patients were successfully treated for a CTO. Of them, we selected all patients (n = 24) who had previous bypass surgery with graft occlusion. Of this final group, 13 patients underwent a percutaneous graft recanalization while 11 underwent native vessel reopening. RESULTS: Primary end points were in-hospital and 3-year rates of death, myocardial infarction, target lesion revascularization, and target vessel revascularization. No events occurred in either group during the in-hospital period. Cumulative 3-year event-free survival in the native vessel and SVG group was 81.8% and 83.9% respectively (P = NS). One death and one TVR occurred in each group. CONCLUSION: In selected cases, SVG reopening instead of the native vessel is feasible. In such a high-risk population, drug-eluting stent implantation in both SVG and native CTO lesions is associated with good long-term outcomes.  相似文献   
963.
AIMS: Alcohol septal ablation (ASA) has been successful in the treatment of symptomatic hypertrophic obstructive cardiomyopathy (HOCM). The aim of this study is to evaluate the effects of ethanol-induced myocardial infarcts on regional myocardial function using cardiac magnetic resonance (CMR) tissue tagging and 3-dimensional (3D) strain analysis. METHODS AND RESULTS: In nine patients (age 52+/-15 years) who underwent ASA, CMR was performed prior to and 6 months after the procedure. Regional myocardial mass was evaluated using cine imaging. Myocardial tagging was used to calculate systolic 3D myocardial strain values. These strain values were used to calculate the shortening index (SI), a robust parameter for myocardial contraction. Maximum end-systolic (ES) SI and systolic SI rate were quantified in three circumferential segments: septum, adjacent, and remote (lateral) myocardium. Compared with baseline, septal and non-septal mass decreased at follow-up (from 72+/-27 to 59+/-21 g; P=0.008 and from 131+/-34 to 109+/-30 g; P=0.008, respectively). In the septum, maximum ES SI and SI rate remained unchanged after ASA. In adjacent myocardium, ES SI remained unchanged, whereas SI rate improved (from -56.5+/-21.1 to -70.0+/-16.7%/s; P=0.02). Both ES SI and SI rate improved significantly in remote myocardium (from -16.9+/-2.8 to -18.8+/-3.2%; P=0.02 and from -70.3+/-9.2 to -86.1+/-15.0%/s; P=0.01, respectively). CONCLUSION: Reduction of left ventricular (LV) outflow tract obstruction in symptomatic HOCM is associated with a significant reduction in myocardial mass and improvement of intramural systolic function in the lateral (remote) wall, indicating reversed LV remodelling.  相似文献   
964.
First, we compared the nature of burden of disease (i.e., manifestations of the disease in daily life) in adolescents and young adults with various chronic digestive disorders with controls. After that, we investigated whether burden of disease is associated with difficulties in school and leisure activities of adolescents and young adults with various digestive disorders. For this purpose, we performed a multicenter study in 5 diagnostic groups (total N = 758; ages 12 to 25 years) including inflammatory bowel diseases (IBD), chronic liver diseases, congenital disorders, celiac disease, and food allergy and a population based control group (N = 306) using a self-report questionnaire. Especially adolescents and young adults with a chronic liver disease, IBD, and food allergy were found to experience daily manifestations of their disease. Several disease burden characteristics, of which especially depression, could be identified as important contributors to difficulties in school performance and leisure activities. This study was supported by a grant from the Foundation for Children’s Welfare Stamps Netherlands. We thank Nel Feijten, Ciska Mastenbroek, Ellen Kampman, Karin Wittebrood, and Maarten Sinaasappel for their support in this study.  相似文献   
965.
966.
967.
Peter de Jonge  Joost van Melle 《European heart journal》2007,28(13):1661; author reply 1661-1661; author reply 1662
With interest, we read the meta-analysis by Nicholson et al.1on depression as an aetiological and prognostic factor in coronaryheart disease (CHD). Focusing on the prognostic risk associatedwith depression,  相似文献   
968.
OBJECTIVE: To examine whether preoperative treatment with diltiazem could ameliorate left ventricular (LV) diastolic dysfunction in patients after coronary artery bypass graft (CABG) surgery. DESIGN: Prospective, nonrandomized clinical study. SETTING: University hospital. PARTICIPANTS: Thirty-four patients with preserved LV function undergoing elective CABG surgery. INTERVENTIONS: According to medical history, patients were divided into 2 groups: patients not receiving diltiazem (n = 17) and patients treated with once-daily oral diltiazem for at least 2 weeks (n = 17). All patients received preoperative beta-blockers. MEASUREMENTS AND MAIN RESULTS: After induction of anesthesia, after sternal closure, and 4 hours after cardiopulmonary bypass (CPB), mitral and pulmonary venous flow velocities were measured with pulsed Doppler. LV short-axis end-diastolic area by Doppler transesophageal echocardiography (TEE) and hemodynamic variables were obtained simultaneously at comparable pulmonary capillary wedge pressures. Postoperatively, increased peak E and A velocities were observed in patients with diltiazem and controls and returned to baseline 4 hours post-CPB in controls. Changes in these velocities did not result in a decreased E/A ratio. Peak A velocity, E/A ratio, and E wave deceleration time were significantly dependent on heart rate, not peak E velocity. End-diastolic area at comparable pulmonary capillary wedge pressure remained unchanged. In relation to diltiazem, only peak A velocity and time velocity integral of the A wave (TVI-A) at 4 hours post-CPB differed from controls. CONCLUSION: Diastolic function is preserved after CABG surgery and is not altered by diltiazem in patients with preserved LV systolic function. The persistence of increased peak A velocity and TVI-A into the postoperative period suggests improved atrial systolic function with diltiazem.  相似文献   
969.
Sandwich-cultured primary rat hepatocytes are often used as an in vitro model in toxicology and pharmacology. However, loss of liver-specific functions, in particular, the decline of cytochrome P450 (P450) enzyme activity, limits the value of this model for prediction of in vivo toxicity. In this study, we investigated whether a hepatic in vitro system with improved metabolic competence enhances the predictability for coumarin-induced in vivo toxicity by using a toxicogenomics approach. Therefore, primary rat hepatocytes were cultured in sandwich configuration in medium containing a mixture of low concentrations of P450 inducers, phenobarbital, dexamethasone, and beta-naphthoflavone. The toxicogenomics approach used enabled comparison of similar mechanistic end-points at the molecular level between in vitro and in vivo conditions, namely, compound-induced changes in multiple genes and signaling pathways. Toxicant-induced cytotoxic effects and gene expression profiles observed in hepatocytes cultured in modified medium and hepatocytes cultured in standard medium (without inducers) were compared with results from a rat in vivo study. Coumarin was used as a model compound because its toxicity depends on bioactivation by P450 enzymes. Metabolism of coumarin toward active metabolites, coumarin-induced cytotoxicity, and gene expression modulation were more pronounced in hepatocytes cultured in modified medium compared with hepatocytes cultured in standard medium. In addition, more genes and biological pathways were similarly affected by coumarin in hepatocytes cultured in modified medium and in vivo. In conclusion, these experiments showed that for coumarin-induced toxicity, sandwich-cultured hepatocytes maintained in modified medium better represent the situation in vivo compared with hepatocytes cultured in standard medium.  相似文献   
970.
The prevalence of asthma and chronic obstructive pulmonary disease (COPD) is rising in most countries, including the Netherlands. It has been suggested that a majority of these cases of (self-reported) symptoms related to asthma/COPD are not diagnosed in general practice. We compared a population screening for underdiagnosed asthma/COPD with a high-risk approach by a questionnaire form with specified questions about asthma/COPD-related symptoms. A case-controlled study including a record review was performed of cases and controls. The results of a population screening were used to classify patients as (a) asthma/COPD, (b) at risk for asthma/COPD, or (c) no asthma/COPD. Eleven hundred fifty-five patients were screened. One hundred fifty-five patients reported previous asthma/COPD-related care (cases). The difference between number of cases and controls in asthma/COPD diagnosis was chosen as main outcome measure. The population screening revealed 85 subjects with a diagnosis of asthma/COPD and 154 subjects with an increased risk. Nineteen diagnoses could be made in cases, and eight diagnoses in controls. The chart review showed that only seven cases and two controls were known to the general practitioner. From this study it can be concluded that in order to reduce the number of un- and underdiagnosed patients, all listed patients in general practice should be screened. However, if screening of all patients is not feasible, active case finding by asking a few questions about shortness of breath or wheezing to all patients in the group of listed individuals is recommended.  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