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   2445951篇
  免费   199298篇
  国内免费   4545篇
耳鼻咽喉   35102篇
儿科学   74660篇
妇产科学   64323篇
基础医学   343589篇
口腔科学   68949篇
临床医学   223352篇
内科学   481961篇
皮肤病学   48949篇
神经病学   208042篇
特种医学   98593篇
外国民族医学   889篇
外科学   371890篇
综合类   57045篇
现状与发展   1篇
一般理论   1084篇
预防医学   197024篇
眼科学   56887篇
药学   182100篇
  4篇
中国医学   4447篇
肿瘤学   130903篇
  2018年   25993篇
  2017年   20079篇
  2016年   21968篇
  2015年   24838篇
  2014年   35866篇
  2013年   54207篇
  2012年   73984篇
  2011年   77846篇
  2010年   45727篇
  2009年   43773篇
  2008年   73719篇
  2007年   78403篇
  2006年   79186篇
  2005年   76990篇
  2004年   74128篇
  2003年   71373篇
  2002年   70369篇
  2001年   113062篇
  2000年   116926篇
  1999年   98977篇
  1998年   28726篇
  1997年   26170篇
  1996年   25983篇
  1995年   25108篇
  1994年   23564篇
  1993年   21982篇
  1992年   79685篇
  1991年   76673篇
  1990年   73788篇
  1989年   71036篇
  1988年   66041篇
  1987年   65011篇
  1986年   61504篇
  1985年   58603篇
  1984年   44447篇
  1983年   37850篇
  1982年   23141篇
  1981年   20553篇
  1980年   19208篇
  1979年   41360篇
  1978年   29079篇
  1977年   24427篇
  1976年   22892篇
  1975年   24018篇
  1974年   29688篇
  1973年   28089篇
  1972年   26260篇
  1971年   24175篇
  1970年   22770篇
  1969年   21111篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
81.
82.
83.
84.
85.
BACKGROUND: The aim of this study was to estimate the cost effectiveness of screening for abdominal aortic aneurysm (AAA). MATERIAL AND METHODS: All 12,639 men born in the years 1921-1933 (aged 64-73) living in Viborg County, Denmark, were randomly allocated either to receive an invitation to abdominal ultrasound scanning for AAA or to be controls. Costs for screening and surveillance were assessed prospectively. Diagnosis Related Group (DRG) costs from 1999 were used concerning admissions with uncomplicated and complicated operations. Admissions for AAA surgery were retrospectively classified according to complications in patient records. RESULTS: Mean follow-up time was 52 months. 76.6% of invited men attended screening, and 191 (4.0%) had an AAA. As previously reported, the cumulative 5-year AAA-specific mortality in the invited group was significantly reduced by 67% compared to the control group (P = 0.003). The costs were estimated to be Euro 11.23 per scan. The costs per life-year saved were Euro 9057 (Euro 5872-20,063) after 5 years, and were expected to decrease to Euro 2708 (Euro 1758-6031) after 10 years and to Euro 1825 (Euro 1185-4063) after 15 years. CONCLUSION: Screening of 64-73 years old males in Denmark seems cost effective.  相似文献   
86.
For patients who receive a liver transplant (LTX) for alcoholic liver disease (ALD), investigators are focusing beyond survival to determine specific alcohol use outcomes. Studies suggest the use of alcohol ranges from 8 to 22% for the first post-transplant year with cumulative rates reaching 30 to 40% by 5 years following transplantation. Yet while investigators are interested in determining specific rates of alcohol use and predictors of use, only three studies since 1990 have been prospective. In 1998, we began a prospective study of post-LTX alcohol consumption in ALD recipients using multiple repeated measures of alcohol use. After 5 years of follow-up, we found that 22% had used any alcohol by the first year and 42% had a drink by 5 years. By 5 years, 26% drank at a heavier use (binge) pattern and 20% drank in a frequent pattern. In a univariate model, predictors of alcohol use included pre-transplant length of sobriety, a diagnosis of alcohol dependence, a history of other substance use, and prior alcohol rehabilitation.  相似文献   
87.
88.
Background: Few studies have examined the use of ultrasound for sciatic nerve localization. The authors evaluated the usefulness of low-frequency ultrasound in identifying the sciatic nerve at three locations in the lower extremity and in guiding needle advancement to target before nerve stimulation.

Methods: In this prospective observational study, 15 volunteers underwent sciatic nerve examination using a curved ultrasound probe in the range of 2-5 MHz and a Philips-ATL 5000 unit (ATL Ultrasound, Bothell, WA) in the gluteal, infragluteal, and proximal thigh regions. Thereafter, an insulated block needle was advanced inline with the ultrasound beam to reach the nerve target, which was further confirmed by electrical stimulation. The quality of sciatic nerve images, ease of needle to nerve contact, threshold stimulating current, and resultant motor response were recorded.

Results: The sciatic nerve was successfully identified in the transverse view as a solitary predominantly hyperechoic structure on ultrasound in all of the three regions examined. The target nerve was visualized easily in 87% and localized within two needle attempts in all patients. Nerve stimulation was successful in 100% after two attempts with a threshold current of 0.42 +/- 0.12 (mean +/- SD) eliciting foot plantarflexion or dorsiflexion.  相似文献   

89.
PURPOSE: To determine the maximum tolerated dose, dose-limiting toxicities, and pharmacokinetic characteristics of doxorubicin encapsulated in a low temperature sensitive liposome (LTSL) when given concurrently with local hyperthermia to canine solid tumors. EXPERIMENTAL DESIGN: Privately owned dogs with solid tumors (carcinomas or sarcomas) were treated. The tumors did not involve bone and were located at sites amenable to local hyperthermia. LTSL-doxorubicin was given (0.7-1.0 mg/kg i.v.) over 30 minutes during local tumor hyperthermia in a standard phase I dose escalation study. Three treatments, given 3 weeks apart, were scheduled. Toxicity was monitored for an additional month. Pharmacokinetics were evaluated during the first treatment cycle. RESULTS: Twenty-one patients were enrolled: 18 with sarcomas and 3 with carcinomas. Grade 4 neutropenia and acute death secondary to liver failure, possibly drug related, were the dose-limiting toxicities. The maximum tolerated dose was 0.93 mg/kg. Other toxicities, with the possible exception of renal damage, were consistent with those observed following free doxorubicin administration. Of the 20 dogs that received > or = 2 doses of LTSL-doxorubicin, 12 had stable disease, and 6 had a partial response to treatment. Pharmacokinetic variables were more similar to those of free doxorubicin than the marketed liposomal product. Tumor drug concentrations at a dose of 1.0 mg/kg averaged 9.12 +/- 6.17 ng/mg tissue. CONCLUSION: LTSL-doxorubicin offers a novel approach to improving drug delivery to solid tumors. It was well tolerated and resulted in favorable response profiles in these patients. Additional evaluation in human patients is warranted.  相似文献   
90.
    
Ohne Zusammenfassung
Endpunkt- und Verlaufsmessungen bei entzündlichen rheumatischen Erkrankungen in Studien und Praxis
  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