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   1351982篇
  免费   101559篇
  国内免费   4307篇
耳鼻咽喉   17099篇
儿科学   44059篇
妇产科学   36628篇
基础医学   200165篇
口腔科学   36415篇
临床医学   131326篇
内科学   261113篇
皮肤病学   26599篇
神经病学   113175篇
特种医学   48711篇
外国民族医学   366篇
外科学   186468篇
综合类   29196篇
现状与发展   1篇
一般理论   486篇
预防医学   116311篇
眼科学   29459篇
药学   99843篇
  6篇
中国医学   3177篇
肿瘤学   77245篇
  2021年   11116篇
  2019年   11822篇
  2018年   16578篇
  2017年   12505篇
  2016年   13475篇
  2015年   15436篇
  2014年   21154篇
  2013年   32590篇
  2012年   45007篇
  2011年   47663篇
  2010年   27497篇
  2009年   25309篇
  2008年   43374篇
  2007年   45790篇
  2006年   45901篇
  2005年   44333篇
  2004年   42204篇
  2003年   40153篇
  2002年   38908篇
  2001年   61349篇
  2000年   62981篇
  1999年   52718篇
  1998年   14760篇
  1997年   13470篇
  1996年   13305篇
  1995年   12624篇
  1994年   11802篇
  1993年   11066篇
  1992年   41976篇
  1991年   41108篇
  1990年   39770篇
  1989年   37681篇
  1988年   34875篇
  1987年   33984篇
  1986年   32433篇
  1985年   30919篇
  1984年   23277篇
  1983年   19778篇
  1982年   11910篇
  1979年   21036篇
  1978年   15011篇
  1977年   12203篇
  1976年   11991篇
  1975年   12260篇
  1974年   14991篇
  1973年   14627篇
  1972年   13516篇
  1971年   12550篇
  1970年   11616篇
  1969年   10547篇
排序方式: 共有10000条查询结果,搜索用时 11 毫秒
981.
Bone and joint sepsis   总被引:1,自引:0,他引:1  
  相似文献   
982.
Preclinical and clinical investigations currently underway are employing novel strategies for combining vaccines with conventional and experimental anticancer therapies. To date, the FDA has not approved a therapeutic cancer vaccine. However, the results of recent investigations suggest an increasing role for vaccines in new models of combination therapy for many types of cancer. This article reviews and discusses therapeutic cancer strategies that employ vaccines in combination with local radiation, chemotherapy, hormone therapy, and anti-CTLA-4 mAb. Preclinical studies have shown that certain anticancer agents have immune modulatory effects that result in up-regulation of surface expression of MHC molecules, tumor-associated antigens, or Fas on malignant cells, rendering them more susceptible to immune destruction. Preliminary results of clinical studies using combination strategies have demonstrated a postvaccination antigen cascade, prolonged time to disease progression, and improved overall survival. Several larger randomized trials are ongoing, and more are required to support these findings.  相似文献   
983.
984.
985.
Diesters based on isosteviol and dicarboxylic acids were synthesized and tested for antituberculous activity. Isosteviol and some of its derivatives exhibit appreciable tuberculostatic properties in vitro, the activity being dependent on the length of the polymethylene spacer connecting two ent-beyeran fragments. The mechanism of the antituberculous action of isosteviol derivatives are discussed. __________ Translated from Khimiko-Farmatsevticheskii Zhurnal, Vol. 40, No. 9, pp. 12–13, September, 2006.  相似文献   
986.
(18)F-FDG PET has a high accuracy in staging head and neck cancer, but its role in patients with clinically and radiographically negative necks (N0) is less clear. In particular, the value of combined PET/CT has not been determined in this group of patients. METHODS: In a prospective study, 31 patients with oral cancer and no evidence of lymph node metastases by clinical examination or CT/MRI underwent (18)F-FDG PET/CT before elective neck dissection. PET/CT findings were recorded by neck side (left or right) and lymph node level. PET/CT findings were compared with histopathology of dissected nodes, which was the standard of reference. RESULTS: Elective neck dissections (26 unilateral, 5 bilateral; a total of 36 neck sides), involving 142 nodal levels, were performed. Only 13 of 765 dissected lymph nodes harbored metastases. Histopathology revealed nodal metastases in 9 of 36 neck sides and 9 of 142 nodal levels. PET was TP in 6 nodal levels (6 neck sides), false-negative in 3 levels (3 neck sides), true-negative in 127 levels (23 neck sides), and false-positive in 6 levels (4 neck sides). The 3 false-negative findings occurred in metastases smaller than 3 mm or because of inability to distinguish between primary tumor and adjacent metastasis. TP and false-positive nodes exhibited similar standardized uptakes (4.8 +/- 1.1 vs. 4.2 +/- 1.0; P = not significant). Sensitivity and specificity were 67% and 85% on the basis of neck sides and 67% and 95% on the basis of number of nodal levels, respectively. If a decision regarding the need for neck dissection had been based solely on PET/CT, 3 false-negative necks would have been undertreated, and 4 false-positive necks would have been overtreated. CONCLUSION: (18)F-FDG PET/CT can identify lymph node metastases in a segment of patients with oral cancer and N0 neck. A negative test can exclude metastatic deposits with high specificity. Despite reasonably high overall accuracy, however, the clinical application of PET/CT in the N0 neck may be limited by the combination of limited sensitivity for small metastatic deposits and a relatively high number of false-positive findings. The surgical management of the N0 neck should therefore not be based on PET/CT findings alone.  相似文献   
987.
It is usual at the end of a year for top tens to feature large in our collective consciousness. These inevitably include the occasional controversial selection and without fail will overlook a number of gems, whether in the field of literature, art, or science. The approaches to such compilations include personal selections, convening expert committees through to letting the market decide. However, it is well recognised that experts can be wrong and markets distorted. A novel approach to identifying the key publications in the field of medicine, Faculty of 1000 Medicine (http://www.f1000medicine.com), uses faculty evaluations to assign ratings to published papers within topics and categories, bringing a flavour of the dynamism of post hoc peer review to biological sciences that exists in other fields of scholarship. Archives of Disease in Childhood has also developed a market led system of peer evaluation through its web based top ten most read articles feature.  相似文献   
988.
OBJECTIVE: Laws that prohibit certain individuals from owning firearms also pertain to ammunition. Whereas retail sales of firearms to criminals are regularly disrupted by instant background checks, sales of ammunition are essentially unchecked and the rate at which criminals acquire ammunition is unknown. This research describes the ammunition market and estimates the rate at which criminals are acquiring ammunition. DESIGN: Criminal background checks conducted on individuals purchasing ammunition in the City of Los Angeles in April and May 2004. SETTING: Los Angeles, CA, USA. SUBJECTS: Ammunition purchasers. MAIN OUTCOME MEASURES: Criminal activity that prohibits one from owning, purchasing, or possessing ammunition. RESULTS: 2.6% (95% CI 1.9% to 3.2%) of ammunition purchasers had a prior felony conviction or another condition that prohibited them from possessing ammunition. During the study period prohibited possessors purchased 10,050 rounds of ammunition in Los Angeles. CONCLUSIONS: These estimates suggest that monitoring ammunition transactions may help reduce the supply of ammunition to criminals and the frequency of injuries from felonious gun assaults. Such a record can also provide information for generating leads on illegal firearm possession.  相似文献   
989.
990.

Background  

Although training and education have long been accepted as integral to disaster preparedness, many currently taught practices are neither evidence-based nor standardized. The need for effective evidence-based disaster training of healthcare staff at all levels, including the development of standards and guidelines for training in the multi-disciplinary health response to major events, has been designated by the disaster response community as a high priority. We describe the application of systematic evidence-based consensus building methods to derive educational competencies and objectives in criteria-based preparedness and response relevant to all hospital healthcare workers.  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