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   2382422篇
  免费   172553篇
  国内免费   4391篇
耳鼻咽喉   35260篇
儿科学   77383篇
妇产科学   67316篇
基础医学   335725篇
口腔科学   67788篇
临床医学   205018篇
内科学   469460篇
皮肤病学   53071篇
神经病学   188059篇
特种医学   95340篇
外国民族医学   1063篇
外科学   368003篇
综合类   53670篇
现状与发展   7篇
一般理论   763篇
预防医学   172398篇
眼科学   55184篇
药学   178587篇
  6篇
中国医学   5008篇
肿瘤学   130257篇
  2018年   22666篇
  2016年   19354篇
  2015年   21917篇
  2014年   30673篇
  2013年   46840篇
  2012年   63115篇
  2011年   66893篇
  2010年   39938篇
  2009年   38360篇
  2008年   64065篇
  2007年   69355篇
  2006年   69825篇
  2005年   67896篇
  2004年   66395篇
  2003年   64338篇
  2002年   63251篇
  2001年   113895篇
  2000年   117698篇
  1999年   99908篇
  1998年   26980篇
  1997年   24431篇
  1996年   24263篇
  1995年   22964篇
  1994年   21593篇
  1993年   20136篇
  1992年   78341篇
  1991年   76284篇
  1990年   74490篇
  1989年   72021篇
  1988年   66765篇
  1987年   65778篇
  1986年   62158篇
  1985年   59247篇
  1984年   44450篇
  1983年   37601篇
  1982年   22147篇
  1981年   20180篇
  1979年   41382篇
  1978年   29109篇
  1977年   25037篇
  1976年   22999篇
  1975年   25672篇
  1974年   30222篇
  1973年   29231篇
  1972年   27625篇
  1971年   25490篇
  1970年   24146篇
  1969年   22734篇
  1968年   21071篇
  1967年   18911篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
21.
22.
Coronary magnetic resonance angiography (CMRA) is a technique in clinical evolution. Current clinical applications include assessment for coronary anomalies, aneurysms, bypass graft patency, and, in experienced centers, the exclusion of proximal and multivessel coronary artery disease (CAD). As local expertise increases and more extensive multicenter data become available, additional applications will be established. CMRA promises to supplement and in some cases obviate the need for X-ray contrast angiography, and to expand our understanding of the pathophysiology of CAD. Zusammenfassung Die Magnetresonanzangiographie der Koronargefäße (CMRA) ist eine sich ständig weiterentwickelnde Technik. Etablierte Anwendungen sind zurzeit die Beurteilung von koronaren Anomalien, Aneurysmen und der Durchgängigkeit von Bypasses. Auch der Ausschluss proximaler Koronarstenosen und einer koronaren Mehrgefäßerkrankung ist in einigen spezialisierten Zentren möglich. Mit zunehmender Erfahrung der jeweiligen Anwender und der Verfügbarkeit von Ergebnissen großer multizentrischer Studien können zukünftig weitere klinische Anwendungen etabliert werden. In der Zukunft könnte die CMRA ergänzende Informationen zur Indikationsstellung einer konventionellen Röntgenangiographie bringen und in einigen Fällen diese Untersuchung sogar ersetzen. Die CMRA wird unseren Einblick in die Pathophysiologie der koronaren Herzerkrankung sicher erweitern.  相似文献   
23.
BACKGROUND: Radioiodine therapy (RIT) combined with glucocorticoids is an effective therapy for Graves' disease, but it is debatable whether glucocorticoids should be applied in patients without Graves' ophthalmopathy (GO). METHODS: The effect of 0.4 - 0.5 mg prednisone every second day over a period of 5 weeks after RIT was monitored over a follow-up period of at least 12 months after RIT. A questionnaire was sent to 186 consecutive patients without GO concerning eye symptoms after RIT. 148 patients (80 %) answered. If eye symptoms had occurred after RIT, additional clinical examination was carried out at our outpatient clinic. The primary endpoint was the absence or onset of GO within the first year after RIT. RESULTS: Within 12 months after RIT the examination confirmed GO in 5 out of 148 patients (3.4 %). In all cases the symptoms were transient. No adverse reaction to the use of prednisone after RIT was noted. CONCLUSIONS: The risk of new GO in the first year after RIT was low and the clinical course of GO was mild when RIT was combined with a low-dose glucocorticoid regimen. Preventive administration of glucocorticoids can therefore be recommended in patients with Graves' disease even without evident GO.  相似文献   
24.
The present study compared four different sites and conditions for the measurement of maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP) in 38 spontaneous breathing tracheotomised patients. Of the patients, 28 had chronic obstructive pulmonary disease (COPD). The four different conditions were: 1) through a cuff inflated cannula (condition A); 2) through the mouth with a deflated cannula (condition B); 3) through the mouth with a phonetic uncuffed cannula (condition C); and 4) through the mouth after stoma closure (condition D). Five trials in each condition were performed using a standardised method. The measurement of both MIP and MEP differed significantly depending on the condition of measurement. MIP taken in condition A was significantly higher when compared with conditions B, C and D. MEP in condition A was significantly higher when compared with condition B and D. In condition A the highest frequency of the best measurement of MIP and MEP was observed at the fourth and fifth effort, respectively. The same results were obtained after the selection of only COPD patients. In conclusion, respiratory muscle assessment differs significantly depending on measurement condition. Measurement through inflated cannula tracheotomy yields higher values of both maximal inspiratory and maximal expiratory pressure.  相似文献   
25.
Severe tuberculosis (TB) requiring intensive care unit (ICU) care is rare but commonly known to be of markedly bad prognosis. The present study aimed to describe this condition and to determine the mortality rate and risk factors associated with mortality. Patients with confirmed TB admitted to ICU between 1990 and 2001 were retrospectively identified and enrolled. Clinical, radiological and bacteriological data at admission and during hospital stay were recorded. A multivariate analysis was performed to identify the predictive factors for mortality. A total of 58 TB patients (12 females, mean age 48 yrs) admitted to ICU were included. Mean Acute Physiology and Chronic Health Evaluation (APACHE) II score at admission was 13.1+/-5.6 and 22 of 58 (37.9%) patients required mechanical ventilation. The in-hospital mortality was 15 of 58 (25.9%); 13 (22.4%) patients died in the ICU. The mean survival of patients who died was 53.6 days (range 1-229), with 50% of the patients dying within the first 32 days. The factors independently associated with mortality were: acute renal failure, need for mechanical ventilation, chronic pancreatitis, sepsis, acute respiratory distress syndrome, and nosocomial pneumonia. These data indicate a high mortality of patients with tuberculosis requiring intensive care unit care and identifies new independently associated risk factors.  相似文献   
26.
27.
Low molecular weight heparins are widely used in the prophylaxis and treatment of thrombotic disorders. The effect of low molecular weight heparins on coagulation was examined ultrastructurally in an animal model. A test and a control group was formed, each consisting of five rabbits. Nadroparine (225 Institute of Chaoy Unit/kg twice daily) was applied to the test group for 10 days. The control group received 1 ml saline solution subcutaneously. Blood and vascular tissue samples collected at the end of the 10th day were evaluated under a JEM 100 B electron microscope. Platelet degranulation and agglutination was observed in the control group. Fibrin materials were detected in the cytoplasms and surroundings of degranulated platelets. Erythrocyte accumulation was remarkable on the vascular endothelium with intact coagulation periods. In the test group, outer membranes of platelets, hyalomere, and granular structures in the granulomeres were detected to be nearly intact. There were rare erythrocytes in the large vascular lumens. The aggregation phase had occurred but no agglutination was detected. Nadroparine seems to preserve consistency of lipoprotein membranes of platelets and granular structures containing enzymes, which contribute to the coagulation mechanisms.  相似文献   
28.
Summary: A female patient with isovaleric acidaemia had a successful outcome from pregnancy.  相似文献   
29.
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