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   2936篇
  免费   335篇
  国内免费   18篇
耳鼻咽喉   20篇
儿科学   58篇
妇产科学   98篇
基础医学   503篇
口腔科学   72篇
临床医学   397篇
内科学   529篇
皮肤病学   52篇
神经病学   189篇
特种医学   176篇
外科学   413篇
综合类   49篇
预防医学   206篇
眼科学   45篇
药学   278篇
中国医学   6篇
肿瘤学   198篇
  2021年   38篇
  2020年   19篇
  2019年   42篇
  2018年   54篇
  2017年   25篇
  2016年   31篇
  2015年   52篇
  2014年   82篇
  2013年   95篇
  2012年   99篇
  2011年   148篇
  2010年   69篇
  2009年   73篇
  2008年   135篇
  2007年   117篇
  2006年   119篇
  2005年   137篇
  2004年   118篇
  2003年   114篇
  2002年   99篇
  2001年   97篇
  2000年   96篇
  1999年   95篇
  1998年   46篇
  1997年   36篇
  1996年   36篇
  1995年   47篇
  1994年   26篇
  1993年   34篇
  1992年   71篇
  1991年   79篇
  1990年   68篇
  1989年   69篇
  1988年   81篇
  1987年   69篇
  1986年   60篇
  1985年   61篇
  1984年   60篇
  1983年   41篇
  1982年   38篇
  1981年   23篇
  1980年   27篇
  1979年   39篇
  1978年   21篇
  1977年   23篇
  1976年   23篇
  1975年   22篇
  1974年   19篇
  1972年   22篇
  1971年   21篇
排序方式: 共有3289条查询结果,搜索用时 0 毫秒
81.
Changing world events over recent years and an increasingly complex patient casemix have led to a review of the equipment used by the Aeromedical Evacuation Squadron of the Royal Air Force. The initial special purpose aeromedical equipment (SPAME) project was completed in 2001 with the new equipment being brought into service in August of the same year. The project incorporated long term planning for replacing the equipment along with its rapidly developing technology, especially with that used for the care of the critically ill. An intensive training programme was simultaneously introduced to support the deployment of this new technology. Critical care teams comprise a consultant anaesthetist, a critical care nurse, a flight nurse attendant (paramedic) and a technician, all of whom attend courses designed specifically to accommodate their role within the team.A considerable amount of work has been undertaken by a dedicated team to ensure this project became a reality and which has resulted in the provision of care to meet the needs of any casualty, anywhere in the world, being achieved using the latest technology proportionate to any hospital-based ICU.  相似文献   
82.

Introduction

Chronic shortage of quality human cadaveric pancreata limits islet transplantation. Porcine islet xenotransplantation is being explored to increase the donor pool. For clinical-ready islets, centralized animal husbandry, Current Good Manufacturing Practice–regulated processing facilities, and organ transportation support are required. Amount of cold ischemia time (CIT) before isolation significantly affects transplantation. The goal of this study was to determine the maximum safe CIT of whole pancreata before islet isolation.

Materials and Methods

Pancreata were rapidly removed from Yorkshire pigs (age, 14–22 days) and stored in modified University of Wisconsin solution or in EuroCollins solution at 4°C. Pancreata were processed with <1 hour CIT (control) or stored for 4 or 12 hours before isolation. Islet yield and percent purity and viability were determined after 7 days of in vitro tissue culture and maturation. Samples from nonprocessed pancreata were collected and snap-frozen in liquid nitrogen at 0, 3, 6, 9, 12, 15, and 24 hours of preservation, then analyzed for adenosine diphosphate/adenosine triphosphate ratio as a measure of tissue energetics.

Results

Up to 12 hours in cold storage had no significant impact on overall islet yield after 7 days of in vitro culture compared with controls; islet yield at the end of the maturation process was 28,700 ± 500 islet equivalents per pancreas (mean ± SEM control yield, 30,300 ± 900 islet equivalents per pancreas); islet purity was 75 ± 5% compared with 74 ± 5% in controls. Islet viability was significantly reduced at 12 hours compared with controls (80 ± 6% vs 96 ± 5%; P < .05). The tissue adenosine diphosphate/adenosine triphosphate ratio was maintained within the first 6 hours (1.6 ± 0.1 to 1.8 ± 0.2; P = NS) but was markedly increased during the 24-hour study (3.3 ± 0.1 at 24 hours), indicating a progressive loss of adenosine triphosphate tissue stores.

Conclusions

Young pig pancreata can be hypothermically stored for up to 12 hours without affecting islet yield and purity; however, islet viability is reduced. These data highlight the need for uniform shipping parameters to standardize islet quality, ideally with CIT <6 hours.  相似文献   
83.
84.
Neurogenic claudication due to spinal stenosis is a common cause of disability in older adults. Conservative treatments are a favourable treatment option. This paper describes the development and delivery of the BOOST (Better Outcomes for Older adults with Spinal Trouble) intervention, a physiotherapist-delivered physical and psychological intervention for the management of neurogenic claudication in older adults. The BOOST intervention is being tested in a multi-centre, randomised controlled trial in UK National Health Service Trusts; delivered by physiotherapists registered with the Health and Care Professionals Council. Participants are aged 65 years or older, registered with a primary care practice, and report symptoms consistent with neurogenic claudication. Intervention content and delivery was initially informed by clinical and patient experts, research evidence, and behaviour change guidelines; and refined following an intervention development day attended by researchers, health professionals, and Patient and Public Involvement representatives. The BOOST intervention comprises 12 group sessions, promoting sustained adherence with a long term home and physical activity programme. Each session includes education and group discussion, individually tailored exercises, and walking. Initial exercise levels are set at a one-to-one assessment. Continued home exercise adherence and increased physical activity following completion of the sessions is facilitated through support telephone calls.
Trial registration ISRCTN12698674.  相似文献   
85.
The total surgical experience of a supraregional paediatric cardiology unit over a nine year period (January 1980 to December 1988) was reviewed to assess the effect of the introduction of the full range of ultrasound techniques. A total of 1517 patients underwent cardiac surgery (955 cardiopulmonary bypass, 562 closed procedures). Of these, 485 patients (32%) did not undergo cardiac catheterisation before operation: 217 bypass (23% of all procedures under cardiopulmonary bypass) and 268 closed procedures (48%). The overall ratio of catheterisations to operations for patients undergoing palliative or corrective surgery fell from 0.97 (1980) to 0.38 (1988). The patients were classified as (a) neonates (0-28 days), (b) infants (one to 12 months), and (c) children (one to 14 years). The main impact of non-invasive surgical referral was in neonates (total catheter:operation ratio 0.38; neonates 0.2 for 1988). The surgical population was further divided according to the principal echocardiographic technique available: (a) 1980-4 cross sectional imaging; (b) 1985-6; imaging plus spectral Doppler ultrasound; (c) 1987-8; imaging plus spectral Doppler ultrasound and colour flow mapping. A fall in the catheter:operation ratio for all age groups was most pronounced in the last four years. This reflects increased familiarity and surgical confidence with non-invasive diagnostic assessment. The introduction of each new echocardiographic technique was associated with a significant fall in the total catheter:operation ratio compared with the preceding period. Six incorrect ultrasound diagnoses were made during the entire period; one of these patients died in the early postoperative period. The integration of Doppler ultrasound with cross sectional imaging has made non-invasive assessment an increasingly practical alternative to preoperative cardiac catheterization.  相似文献   
86.
87.
We performed two surveys to uncover the status of philanthropic endowments in general internal medicine divisions. The initial survey of U.S. medical school departments of medicine found that only 14.1% of general internal medicine divisions hold endowments versus 21.9% of all other divisions, and that endowment sources for general medicine are atypical. The second survey of successfully endowed divisions found that sympathetic administrators and active pursuit of endowments were associated with endowment success. Aggressive pursuit of endowments, publicizing successes of general medicine, and consideration of endowment sources noted in this study are recommended to improve philanthropic contributions to general internal medicine.  相似文献   
88.
Beneficial effects of recombinant human GH on cardiac function have been reported in humans with GH deficiency and in patients with idiopathic dilated cardiomyopathy. No randomized controlled trial has been performed on the effects of recombinant human GH on cardiac function in patients with ischemic cardiac failure. We therefore randomly assigned 22 patients with ischemic cardiac failure (left ventricular ejection fraction, <40%; 19 men and 3 women; mean age, 64 yr) to receive 6 months of unblinded therapy with recombinant human GH (2.0 IU/d) or no treatment. Primary end points were left ventricular ejection fraction and left ventricular mass. Left ventricular end-diastolic volume, left ventricular end-systolic volume, and myocardial perfusion, both at rest and during exercise, were assessed as well. Cardiac imaging techniques were electrocardiographically gated single photon emission computer tomography and magnetic resonance imaging. In addition, biochemical and biometric measurements were performed. Nineteen patients completed the study (10 controls and 9 GH-treated subjects). IGF-I and IGF-binding protein-3 increased significantly after recombinant human GH treatment (+24% and +58%, respectively) compared with control values (-14% and +5%; P < 0.05). Left ventricular ejection fraction, left ventricular end-diastolic volume, left ventricular end-systolic volume, left ventricular mass, and myocardial perfusion were not influenced by recombinant human GH therapy. We conclude that 6 months of recombinant human GH treatment in patients with ischemic cardiac failure had no beneficial effect on left ventricular function and mass.  相似文献   
89.

Background

Selective non-operative management (SNOM) of penetrating abdominal wounds has become increasingly common in the past two or three decades and is now accepted as routine management for stab wounds. Gunshot wounds are more frequently managed with mandatory laparotomy but recently SNOM has been successfully applied. This review systematically appraises the evidence behind SNOM for civilian abdominal gunshot wounds.

Methods

A Medline search from 1990 to present identified civilian studies examining success rates for SNOM of abdominal gunshot wounds. Case reports, editorials and abstracts were excluded. All other studies meeting the inclusion criteria of reporting the success rate of non-operative management of abdominal gunshot wounds were analysed.

Results

Sixteen prospective and six retrospective studies met the inclusion criteria, including 18,602 patients with abdominal gunshot wounds. 32.2% (n = 6072) of patients were initially managed non-operatively and 15.5% (n = 943) required a delayed laparotomy. The presence of haemodynamic instability, peritonitis, GI bleeding or any co-existing pathology that prevented frequent serial examination of the abdomen from being performed were indications for immediate laparotomy in all studies. Delayed laparotomy results in similar outcomes to those in patients subjected to immediate laparotomy. Implementation of SNOM reduces the rates of negative and non-therapeutic laparotomies and reduces overall length of stay.

Conclusions

SNOM can be safely applied to some civilian patients with abdominal gunshot wounds and reduces the rates of negative or non-therapeutic laparotomy. Patients who require delayed laparotomy have similar rates of morbidity and mortality and similar length of stay to those patients who undergo immediate laparotomy.  相似文献   
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