首页 | 官方网站   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   2753931篇
  免费   197897篇
  国内免费   7963篇
医药卫生   2959791篇
  2021年   22957篇
  2019年   23928篇
  2018年   35257篇
  2017年   26533篇
  2016年   30176篇
  2015年   33969篇
  2014年   45228篇
  2013年   67789篇
  2012年   93361篇
  2011年   97810篇
  2010年   57561篇
  2009年   54105篇
  2008年   90209篇
  2007年   95915篇
  2006年   96480篇
  2005年   92680篇
  2004年   88857篇
  2003年   85358篇
  2002年   82102篇
  2001年   131161篇
  2000年   134169篇
  1999年   113092篇
  1998年   31918篇
  1997年   28492篇
  1996年   28714篇
  1995年   27856篇
  1994年   25504篇
  1993年   23818篇
  1992年   86769篇
  1991年   83067篇
  1990年   80182篇
  1989年   77336篇
  1988年   70726篇
  1987年   69138篇
  1986年   64605篇
  1985年   61536篇
  1984年   45743篇
  1983年   38589篇
  1982年   22844篇
  1981年   20268篇
  1979年   39645篇
  1978年   27923篇
  1977年   23696篇
  1976年   21831篇
  1975年   23282篇
  1974年   27407篇
  1973年   26013篇
  1972年   24364篇
  1971年   22537篇
  1970年   20769篇
排序方式: 共有10000条查询结果,搜索用时 730 毫秒
991.
Introduction The associations between vitamin D receptor (VDR) Bsm I and Fok I genotypes, parity, and risk of osteoporotic hip fracture were evaluated in a statewide population-based case-control study in Utah.Methods Women age 50–89 years with hip fracture (n=882) were ascertained via surveillance of 18 Utah hospitals from 1997 to 2001. Age-matched controls were randomly selected (n=897). Participants were interviewed in their homes, and blood samples were collected for genotyping.Results In logistic regression analyses that controlled for multiple confounders, Bsm I VDR genotype but not Fok I genotype was associated with risk of osteoporotic hip fracture (OR bb vs. BB genotype: 0.68; 95% CI: 0.50, 0.95). In similar analyses, no overall association was observed between parity status and risk of osteoporotic hip fracture. However, the effect of VDR genotype was modified by parity status. Among nulliparous women (n=140), Bsm I genotype was not associated with risk of hip fracture (OR bb vs. BB: 0.82; 95% CI: 0.28, 2.4); among primiparous women (n=133), bb genotype was associated with increased risk of hip fracture (OR bb vs. BB: 3.30; 95% CI: 0.96, 11.29); among multiparous women (n=1,400), bb genotype was associated with decreased risk of hip fracture (OR bb vs. BB: 0.59; 95% CI: 0.42, 0.84).Conclusion VDR Bsm I genotype was associated with risk of hip fracture in Utah women, and this effect was modified by parity status. Hormonal or lifestyle factors related to parity may underlie this interaction.  相似文献   
992.
The new treatment strategy for Peritoneal Surface Malignancy combines a cytoreductive surgery and perioperative intraperitoneal chemotherapy. Cytoreduction removes all macroscopic tumor. Intraperitoneal chemotherapy avoids implantation of microscopic residual tumor cells on intra-abdominal surfaces when it is administered intraoperatively and/or early in the postoperative period. Delivering cytotoxic drugs directly into the peritoneal cavity maximizes dose intensity and minimizes systemic toxicity. Hyperthermia is selectively cytotoxic for malignant cells and potentiates the effect of chemotherapy. Implementation of this procedure makes the perioperative personnel to face a risk of exposure to cytotoxic agents. Furthermore, peritonectomies and electro-evaporation of tumor nodules are performed with high voltage electrocautery, generating a large amount of surgical smoke during several hours. Inhalation of these fumes may be also a risk for healthcare workers. In this article, we analyse in depth these new risks of the operating room personnel, we review the literature, and we give guidelines for secure performance of cytoreductive surgery and hyperthermic intraoperative intraperitoneal chemotherapy, as well as for early postoperative intraperitoneal chemotherapy administration. These new procedures are safe techniques for patients and healthcare workers provided adequate policies are adopted to avoid occupational exposure.  相似文献   
993.
Poor results after surgery for bronchioloalveolar carcinoma.   总被引:2,自引:0,他引:2  
BACKGROUND: Bronchioloalveolar carcinoma (BAC) is suggested to be less aggressive than other types of lung cancer. To assess the option of treatment modification, actual outcome data were studied and compared with results for other types of lung cancer. METHOD: Retrospective analysis of all consecutive patients who underwent resection for stage I lung cancer in our hospital. For 18 BAC cases, histological specimens were re-evaluated and in three cases diagnosis was revised. RESULTS: In the period 1989 through 2000, 15 patients with BAC and 260 patients with other tumour types underwent surgery in our hospital. Five-year survival rates were 24 and 53%, respectively, (p = 0.01). CONCLUSIONS: Given the poor results after standard surgery, parenchyma-sparing operations do not seem justified in patients with invasive BAC.  相似文献   
994.
995.
996.
There are no data available combining transbronchial needle aspiration (TBNA) of mediastinal lymph nodes and positron emission tomography (PET) in the staging of nonsmall cell lung cancer (NSCLC). The aim of the current study was to determine if these two methods can enhance the negative predictive value of the individual modality alone, for a specific lymph node station, and if this integrated approach can reduce the number of mediastinoscopies. A total of 113 patients with enlarged mediastinal lymph nodes (> or = 1 cm), who underwent both TBNA and PET scanning, were included. In 51 patients, histopathology, confirmed by surgical lymph node dissection, was compared with PET results and TBNA. Sensitivity, specificity, positive predictive value, negative predictive value and accuracy to detect malignant lymphadenopathy was 68 (13/19), 89 (119/134), 46 (13/28), 95 (119/125) and 86% (132/152) for PET, respectively; 54% (6/11), 100 (53/53), 100 (6/6), 91 (53/58) and 92% (59/64), respectively for TBNA; and 100 (11/11), 94 (50/53), 79 (11/14), 100 (50/50) and 95 (61/64) for combined TBNA and PET, respectively. Combination of transbronchial needle aspiration and positron emission tomography has the potential to allow adequate mediastinal staging of nonsmall cell lung cancer with enlarged lymph nodes in most patients without the need for mediastinoscopy.  相似文献   
997.
998.
A national conference on organ donation after cardiac death (DCD) was convened to expand the practice of DCD in the continuum of quality end-of-life care. This national conference affirmed the ethical propriety of DCD as not violating the dead donor rule. Further, by new developments not previously reported, the conference resolved controversy regarding the period of circulatory cessation that determines death and allows administration of pre-recovery pharmacologic agents, it established conditions of DCD eligibility, it presented current data regarding the successful transplantation of organs from DCD, it proposed a new framework of data reporting regarding ischemic events, it made specific recommendations to agencies and organizations to remove barriers to DCD, it brought guidance regarding organ allocation and the process of informed consent and it set an action plan to address media issues. When a consensual decision is made to withdraw life support by the attending physician and patient or by the attending physician and a family member or surrogate (particularly in an intensive care unit), a routine opportunity for DCD should be available to honor the deceased donor's wishes in every donor service area (DSA) of the United States.  相似文献   
999.
目的:在瑞典儿童群体中,研究瑞典语译的出院后行为学问卷调查(PHBQ)的有效性和可行性。方法:利用回译的方法,将PHBQ翻译成瑞典语。340名2~13岁间的小儿被纳入研究对象,均曾有过麻醉下接受选择性外科手术或诊断过程的住院史。利用旋光性甲戊炔醇主成分分析的探测性因素分析法分析结果。选择一匹配于该模型的可靠的适合度测量法,利用证实性的因素分析,检查数据的适合度(所有因素P〉0.09)。  相似文献   
1000.
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-23

京公网安备 11010802026262号