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   559篇
  免费   38篇
  国内免费   7篇
耳鼻咽喉   3篇
儿科学   31篇
妇产科学   6篇
基础医学   37篇
口腔科学   6篇
临床医学   97篇
内科学   85篇
皮肤病学   4篇
神经病学   62篇
特种医学   76篇
外科学   94篇
综合类   14篇
预防医学   22篇
眼科学   2篇
药学   28篇
肿瘤学   37篇
  2023年   4篇
  2021年   3篇
  2020年   3篇
  2019年   5篇
  2018年   3篇
  2016年   7篇
  2015年   12篇
  2014年   8篇
  2013年   16篇
  2012年   25篇
  2011年   16篇
  2010年   15篇
  2009年   23篇
  2008年   22篇
  2007年   21篇
  2006年   30篇
  2005年   32篇
  2004年   36篇
  2003年   19篇
  2002年   16篇
  2001年   24篇
  2000年   31篇
  1999年   18篇
  1998年   18篇
  1997年   6篇
  1996年   14篇
  1995年   13篇
  1994年   13篇
  1993年   13篇
  1992年   10篇
  1991年   8篇
  1990年   9篇
  1989年   7篇
  1988年   14篇
  1987年   6篇
  1986年   5篇
  1985年   7篇
  1984年   5篇
  1983年   4篇
  1982年   4篇
  1981年   3篇
  1980年   4篇
  1979年   4篇
  1978年   4篇
  1977年   7篇
  1975年   3篇
  1973年   3篇
  1971年   4篇
  1968年   4篇
  1967年   3篇
排序方式: 共有604条查询结果,搜索用时 15 毫秒
71.
72.
We describe a simple adaptation of the Water Pik (Teledyne Water Pik, Fort Collins, Colorado) irrigating device which allows vigorous, direct-vision agitation of the bladder wall. Three groups of mongrel dogs were subjected to cystoscopy and either syringe barbotage, half-speed Water Pik irrigation, or full-speed Water Pik irrigation of the bladder wall. Transitional cell counts were then done on centrifuged aliquots of each bladder wash specimen. The average number of transitional cells per high-power field were similar between the control group and the syringe barbotage group (2.5 and 1.5 respectively). However, both the half-speed and the full-speed Water Pik groups demonstrated statistically higher cell counts (5.7 and 13.7) when compared to both the controls and syringe barbotage groups. We conclude that Water Pik irrigation is an effective method to increase cell yield in bladder wash specimens.  相似文献   
73.
Background: Calcitonin gene-related peptide (CGRP) is known to have an extremely potent and prolonged vasodilator effect on the coronary arteries. Studies have shown that CGRP increased coronary blood flow and alleviated reperfusion injury in vitro. It is still unknown, however, whether exogenous CGRP has a protective effect on the reperfusion heart associated with cardiopulmonary bypass (CPB). Methods: An in vivo porcine model of CPB was established. Twenty pigs, 10 controls and 10 CGRP used animals (CGRP group), were performed a median sternotomy followed by a standard CPB. All the hearts were arrested for 45 minutes. In the CGRP group, 1mg/kg CGRP was added into the cardioplegia, and another 1mg/kg was reperfused just before the aortic cross-clamp was removed. In both groups, myocardial microvascular perfusion, coronary arterial microvessel diameter and microvessel blood flow were detected by a laser doppler flowmeter and a contact microscope with TV monitor on five consecutive time perioperatively. Result: Myocardial microvascular perfusion was significantly higher and coronary arterial microvessel diameter was larger in the CGRP group on every point of time of reperfusion compared to those in the control group. In the CGRP group, microvessel blood flow also improved significantly than that in the control group during reperfusion. Conclusion: CGRP improves myocardial microcirculation during cardiac ischemia-reperfusion associated with CPB and could become a new, potent myocardial protector.  相似文献   
74.
75.
Amplitude and habituation of event-related potentials are abnormal in migraine. We investigated 43 migraine and 41 healthy families to evaluate the influences of age, sex and familial contribution on the variance of amplitude and habituation of the contingent negative variation (CNV). Analysis of individual differences in relation to the CNV habituation was performed. The study demonstrated that habituation of the early CNV component characterizes migraine considerably better than the CNV amplitudes. Habituation, however, is strongly influenced by age. Migraine adults and children generally showed reduced habituation. Surprisingly, more than 30% of the healthy adults demonstrated a marked loss of habituation. The reduced CNV habituation represented a high sensitivity but low specificity to migraine, especially in children. CNV amplitude and habituation parameters revealed a considerable familial contribution associated with migraine. No familial influence on either morphology or habituation of the CNV in healthy families or between healthy members of migraine families was observed. The low specificity and familial transmission of CNV parameters in members of migraine families suggest that increased amplitudes and reduced habituation of CNV do not constitute a primary risk factor for migraine, but rather represent a predisposition. Genetic components probably affect variation of the CNV amplitude and habituation.  相似文献   
76.
77.
The transcatheter closure of atrial septal defects is generally accepted as an alternative to surgical therapy in selected patients. Potential complications of these devices are a matter of concern, as well as the very complicated implantation technique required for some systems. We report on a 17 year old patient in whom embolization of a fractured umbrella arm into a peripheral branch of the left pulmonary artery occurred. A 35 mm-ASDOS-Device (protected trademark of the Dr. Osypka GmbH/Grenzach-Wyhlen, Germany) had been implanted 4 years ago. The perfusion scintigraphy of the left lung showed normal pulmonary blood flow. Echocardiography failed to demonstrate instability of the double-umbrella device. The patient was always free of any symptoms. Due to the permanent stresses between device and heart, late fractures of the device and embolizations of fragments are possible. It can be concluded that patients who underwent transcatheter closure of an ASD require lifelong follow-up.  相似文献   
78.
Captopril mediated decrease of aortic regurgitation   总被引:1,自引:0,他引:1  
The effect of captopril mediated afterload reduction on aortic regurgitation was investigated in 10 patients. Regurgitation was quantitated by means of the regurgitation fraction and the relation of regurgitant volume to end diastolic volume. These variables were derived from gated radionuclide ventriculography. After captopril treatment the blood concentration of angiotensin I rose whereas that of angiotensin II fell significantly. The conversion of angiotensin I to II was reduced to about 50% of the control value. Whereas blood pressure and heart rate did not change significantly, the regurgitation fraction and the regurgitant volume, normalised to end diastolic volume, were significantly reduced by captopril treatment. The ejection fraction remained essentially unchanged. These findings suggest that captopril reduces aortic regurgitation by reducing afterload.  相似文献   
79.
The relative effects of two beta-lactam antibiotics, penicillin-binding protein (PBP) 2-specific imipenem and PBP 3-specific ceftazidime, upon in vitro induction of lipopolysaccharide (LPS) release were investigated against smooth- and rough-LPS mutant isolates of Pseudomonas aeruginosa. Free LPS liberated from both isolates are 10- to 40-fold higher for ceftazidime-exposed cultures than control or imipenem-treated cultures after 4-8 h at 35 degrees C despite equivalent MICs. Lethalities of filtrates in mice correlated with in vitro endotoxin assay results. Sub-MIC levels of ceftazidime induced filamentation and LPS release without significant bacterial lysis. Amounts released not only matched the quantities achieved at inhibitory concentrations (e.g., 1-, 2-, and 50-times MIC) of ceftazidime but significantly exceeded levels of LPS liberated by exposure to imipenem, less than or equal to 100 times its MIC. Sub-MIC levels of imipenem released relatively small amounts of free LPS while reducing colony counts approximately 2 logs more than equivalent amounts of ceftazidime after 2 h. Data suggest that ceftazidime-induced filamentation releases larger quantities of bioreactive LPS than nonfilamentous fast-lysing imipenem.  相似文献   
80.
This consensus paper introduces a classification of headache care facilities on behalf of the German Migraine and Headache Society. This classification is based on the recommendations of the International Association for the Study of Pain (IASP) and the European Headache Federation (EHF) and was adapted to reflect the specific situation of headache care in Germany. It defines three levels of headache care: headache practitioner (level 1), headache outpatient clinic (level 2) and headache centers (level 3). The objective of the publication is to define and establish reliable criteria in the field of headache care in Germany.  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