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   2355435篇
  免费   171927篇
  国内免费   3333篇
耳鼻咽喉   32082篇
儿科学   76135篇
妇产科学   62880篇
基础医学   348680篇
口腔科学   63654篇
临床医学   212477篇
内科学   458050篇
皮肤病学   51799篇
神经病学   185784篇
特种医学   88134篇
外国民族医学   489篇
外科学   354333篇
综合类   47561篇
现状与发展   12篇
一般理论   855篇
预防医学   183723篇
眼科学   54377篇
药学   175380篇
  11篇
中国医学   4576篇
肿瘤学   129703篇
  2021年   19078篇
  2019年   19679篇
  2018年   27194篇
  2017年   20464篇
  2016年   22844篇
  2015年   25763篇
  2014年   36271篇
  2013年   54239篇
  2012年   75085篇
  2011年   79905篇
  2010年   47302篇
  2009年   44772篇
  2008年   75011篇
  2007年   79901篇
  2006年   80684篇
  2005年   78190篇
  2004年   74739篇
  2003年   72017篇
  2002年   69676篇
  2001年   108779篇
  2000年   111484篇
  1999年   93526篇
  1998年   27054篇
  1997年   23710篇
  1996年   24091篇
  1995年   22768篇
  1994年   20918篇
  1993年   19747篇
  1992年   72020篇
  1991年   70091篇
  1990年   68408篇
  1989年   65672篇
  1988年   60313篇
  1987年   59138篇
  1986年   55233篇
  1985年   53020篇
  1984年   39327篇
  1983年   33404篇
  1982年   19870篇
  1979年   35870篇
  1978年   25655篇
  1977年   21238篇
  1976年   20333篇
  1975年   21816篇
  1974年   26149篇
  1973年   24807篇
  1972年   23205篇
  1971年   22038篇
  1970年   20247篇
  1969年   19316篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
81.
BACKGROUND: Previous research has demonstrated that academic and neuropsychological functions are compromised in pediatric bipolar disorder (PBD). Investigation of the degree to which neuropsychological deficits might contribute to those academic problems is needed to aid in the recognition and intervention for school achievement difficulties in PBD. METHODS: A sample of 55 children and adolescents with PBD with and without attention-deficit/hyperactivity disorder (ADHD) (PBD group, n = 28; PBD+ADHD group, n = 27) were tested with a computerized neurocognitive battery and standardized neuropsychological tests. Age range of subjects was 7-17 years, with the mean age of 11.97 (3.18) years. Parents completed a structured questionnaire on school and academic functioning. RESULTS: Logistic regression analyses indicated that executive function, attention, working memory, and verbal memory scores were poorer in those with a history of reading/writing difficulties. A separate logistic regression analysis found that attentional dysfunction predicted math difficulties. These relationships between neuropsychological function and academic difficulties were not different in those with PBD+ADHD than in those with PBD alone. CONCLUSIONS: In PBD neuropsychological deficits in the areas of attention, working memory, and organization/problem solving skills all contribute to academic difficulties. Early identification and intervention for these difficulties might help prevent lower academic achievement in PBD.  相似文献   
82.
83.
84.
85.
86.
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   

87.
88.
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   
89.
90.
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