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   71805篇
  免费   4414篇
  国内免费   270篇
耳鼻咽喉   1120篇
儿科学   2036篇
妇产科学   1337篇
基础医学   7987篇
口腔科学   1456篇
临床医学   7042篇
内科学   14894篇
皮肤病学   1129篇
神经病学   6937篇
特种医学   2497篇
外国民族医学   5篇
外科学   12475篇
综合类   855篇
一般理论   94篇
预防医学   5963篇
眼科学   1415篇
药学   4561篇
中国医学   111篇
肿瘤学   4575篇
  2023年   396篇
  2022年   653篇
  2021年   1777篇
  2020年   933篇
  2019年   1555篇
  2018年   1822篇
  2017年   1311篇
  2016年   1352篇
  2015年   1490篇
  2014年   2286篇
  2013年   3215篇
  2012年   4875篇
  2011年   5068篇
  2010年   2770篇
  2009年   2461篇
  2008年   4468篇
  2007年   4740篇
  2006年   4590篇
  2005年   4560篇
  2004年   4305篇
  2003年   3959篇
  2002年   3682篇
  2001年   569篇
  2000年   496篇
  1999年   643篇
  1998年   748篇
  1997年   671篇
  1996年   593篇
  1995年   523篇
  1994年   515篇
  1993年   434篇
  1992年   387篇
  1991年   388篇
  1990年   319篇
  1989年   300篇
  1988年   299篇
  1987年   279篇
  1986年   286篇
  1985年   377篇
  1984年   447篇
  1983年   372篇
  1982年   537篇
  1981年   499篇
  1980年   459篇
  1979年   212篇
  1978年   281篇
  1977年   268篇
  1976年   212篇
  1975年   223篇
  1973年   189篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
961.
962.
963.
Introduction: Patients presenting with cirrhosis and hepatic tumours represent a fragile group that have typically been avoided in early series of laparoscopic liver resection. This study was undertaken to evaluate the results of a laparoscopic hepatectomy in the setting of cirrhosis.Methods: Subgroup analysis of patients with cirrhosis within a series of 327 patients undergoing a laparoscopic resection was performed. Comparisons were made with patients without cirrhosis where appropriate to highlight differences in patient selection and outcomes. Specific variables assessed included operative details and short-term outcomes including length of stay (LOS), morbidity and mortality. Outcomes specific to hepatocellular carcinoma (HCC) were also assessed.Results: There were 52 patients with cirrhosis undergoing a laparoscopic hepatic resection. Ninety per cent of patients were Childs class A, with a median model for end-stage liver disease (MELD) score of 8. Hepatitis C was the most common cause of cirrhosis (88.5%), whereas the most common indication for an operation was HCC (71.2%). Resections were generally limited, with the median number of segments resected being 2 (range: 1–4). Complications occurred in 13 (25%) patients, with a 90-day mortality of 5.8%. The median LOS was 3 days.Conclusions: A laparoscopic hepatectomy is safe in the setting of cirrhosis, provided the application of appropriate selection criteria and sufficient experience with the procedure.  相似文献   
964.
965.
Chronic Obstructive Pulmonary Disease (COPD) is a heterogeneous disease with a wide range of clinical phenotypes that vary from predominantly airway disease (chronic bronchitis) to predominantly parenchymal disease (emphysema). Current advances for the treatment of COPD are increasingly focused on targeted treatments and development of novel biomarker-based diagnostics (Dx)'s to select the patients most likely to benefit. Clinical trial planning and design with biomarkers includes additional considerations beyond those for conventional trials in un-selected populations, e.g., the heterogeneity of COPD phenotypes in the population, the ability of a biomarker to predict clinically meaningful phenotypes that are differentially associated with the response to a targeted treatment, and the data needed to make Go/No Go decisions during clinical development.

We developed the Clinical Trial Object Oriented Research Application (CTOORA), a computer-aided clinical trial simulator of COPD patient outcomes, to inform COPD trial planning with biomarkers. CTOORA provides serial projections of trial success for a range of hypothetical and plausible scenarios of interest. In the absence of data, CTOORA can identify characteristics of a biomarker-based Dx needed to provide a meaningful advantage when used in a clinical trial. We present a case study in which CTOORA is used to identify the scenarios for which a biomarker may be used successfully in clinical development. CTOORA is a tool for robust clinical trial planning with biomarkers, to guide early-to-late stage development that is positioned for success.  相似文献   

966.

Background and objectives

The Statewide Sharing variance to the national kidney allocation policy allocates kidneys not used within the procuring donor service area (DSA), first within the state, before the kidneys are offered regionally and nationally. Tennessee and Florida implemented this variance. Known geographic differences exist between the 58 DSAs, in direct violation of the Final Rule stipulated by the US Department of Health and Human Services. This study examined the effect of Statewide Sharing on geographic allocation disparity over time between DSAs within Tennessee and Florida and compared them with geographic disparity between the DSAs within a state for all states with more than one DSA (California, New York, North Carolina, Ohio, Pennsylvania, Texas, and Wisconsin).

Design, setting, participants, & measurements

A retrospective analysis from 1987 to 2009 was conducted using Organ Procurement and Transplant Network data. Five previously used indicators for geographic allocation disparity were applied: deceased-donor kidney transplant rates, waiting time to transplantation, cumulative dialysis time at transplantation, 5-year graft survival, and cold ischemic time.

Results

Transplant rates, waiting time, dialysis time, and graft survival varied greatly between deceased-donor kidney recipients in DSAs in all states in 1987. After implementation of Statewide Sharing in 1992, disparity indicators decreased by 41%, 36%, 31%, and 9%, respectively, in Tennessee and by 28%, 62%, 34%, and 19%, respectively in Florida, such that the geographic allocation disparity in Tennessee and Florida almost completely disappeared. Statewide kidney allocations incurred 7.5 and 5 fewer hours of cold ischemic time in Tennessee and Florida, respectively. Geographic disparity between DSAs in all the other states worsened or improved to a lesser degree.

Conclusions

As sweeping changes to the kidney allocation system are being discussed to alleviate geographic disparity—changes that are untested run the risk of unintended consequences—more limited changes, such as Statewide Sharing, should be further studied and considered.  相似文献   
967.
968.
Understanding the balance between fidelity and adaptation for evidence‐based interventions has the potential to improve their translation from research to practice. The Translation into Practice study explores variation in program implementation within organizations utilizing the RESPECT program, an HIV counseling and testing intervention. Counselors (N = 70) were interviewed using a semistructured interview guide to examine both the influential factors on, and the subsequent adaptations to, RESPECT. Almost all counselors reported making adaptations (N = 69). Adaptations were made both to key characteristics (mean [M] = 2.24, standard deviation [SD] = 1.3) and to core components (M = 0.5, SD = 0.8). Counselors identified the environmental context and factors within the counseling context as common influences leading to adaptation. These findings suggest adaptations were a routine part of program usage. To improve implementation of the RESPECT program, further research is needed to assess the degree to which adaptations can be made to better meet the needs of agencies and clients without compromising fidelity.  相似文献   
969.
970.
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