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   38831篇
  免费   3268篇
  国内免费   127篇
耳鼻咽喉   377篇
儿科学   966篇
妇产科学   728篇
基础医学   4853篇
口腔科学   1007篇
临床医学   5654篇
内科学   7760篇
皮肤病学   804篇
神经病学   3192篇
特种医学   1307篇
外国民族医学   1篇
外科学   4718篇
综合类   552篇
一般理论   40篇
预防医学   4549篇
眼科学   567篇
药学   2720篇
  1篇
中国医学   37篇
肿瘤学   2393篇
  2022年   257篇
  2021年   663篇
  2020年   373篇
  2019年   674篇
  2018年   658篇
  2017年   510篇
  2016年   631篇
  2015年   738篇
  2014年   1038篇
  2013年   1511篇
  2012年   2247篇
  2011年   2216篇
  2010年   1203篇
  2009年   1074篇
  2008年   2022篇
  2007年   2074篇
  2006年   2048篇
  2005年   2013篇
  2004年   1911篇
  2003年   1757篇
  2002年   1809篇
  2001年   1070篇
  2000年   1063篇
  1999年   952篇
  1998年   481篇
  1997年   413篇
  1996年   368篇
  1995年   358篇
  1994年   281篇
  1993年   302篇
  1992年   648篇
  1991年   675篇
  1990年   619篇
  1989年   566篇
  1988年   508篇
  1987年   500篇
  1986年   518篇
  1985年   501篇
  1984年   396篇
  1983年   336篇
  1982年   271篇
  1981年   249篇
  1980年   192篇
  1979年   352篇
  1978年   276篇
  1977年   227篇
  1974年   235篇
  1973年   222篇
  1972年   183篇
  1971年   197篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
141.
142.
This paper describes the case of an industrial radiographer who was seriously overexposed to gamma radiation. The exact circumstances of this exposure were not established but it was concluded that he was repeatedly irradiated probably to a total average whole body dose of at least 10 Gy over several years. Also, a much larger dose to a hand required its partial amputation. He developed myelodysplasia, which progressed to acute myeloid leukaemia from which he died. Karyotypic examination of the leukaemic blasts showed changes very similar to those associated with secondary leukaemia that may develop after radio or chemotherapy. The paper describes his medical case history, the investigation of his workplace, and the attempts to estimate his radiation dose by chromosomal analysis of blood lymphocytes and electron spin resonance of dental enamel and bone.  相似文献   
143.
144.
The paper reports the results of a study on benchmarking activities undertaken by the procurement organization within the National Health Service (NHS) in Scotland, namely National Procurement (previously Scottish Healthcare Supplies Contracts Branch). NHS performance is of course politically important, and benchmarking is increasingly seen as a means to improve performance, so the study was carried out to determine if the current benchmarking approaches could be enhanced. A review of the benchmarking activities used by the private sector, local government and NHS organizations was carried out to establish a framework of the motivations, benefits, problems and costs associated with benchmarking. This framework was used to carry out the research through case studies and a questionnaire survey of NHS procurement organizations both in Scotland and other parts of the UK. Nine of the 16 Scottish Health Boards surveyed reported carrying out benchmarking during the last three years. The findings of the research were that there were similarities in approaches between local government and NHS Scotland Health, but differences between NHS Scotland and other UK NHS procurement organizations. Benefits were seen as significant and it was recommended that National Procurement should pursue the formation of a benchmarking group with members drawn from NHS Scotland and external benchmarking bodies to establish measures to be used in benchmarking across the whole of NHS Scotland.  相似文献   
145.
Despite the widespread use of monoamine oxidase inhibitors (MAOIs) and the well-known adverse event of hypertensive crisis, few studies have addressed the acute cardiovascular response to an MAOI dose. We prospectively measured pulse and blood pressure changes just before and at 1, 2, 3, and 4 hours after MAOI administration in 18 patients. Significant but asymptomatic increases from baseline in mean systolic and diastolic blood pressure occurred within 2 hours after MAOI administration, with return to near baseline by 4 hours. The mechanism of this reaction is unknown.  相似文献   
146.
Summary: This study was undertaken to determine maternal impact of corticosteroids administered for the promotion of fetal lung maturity in mothers with the HELLP syndrome. Twenty-seven of 427 women with the HELLP syndrome treated between 1980–1991 received a full course of steroids prior to preterm delivery. This group was compared to 27 matched control patients with the HELLP syndrome who received no corticosteroids. Subjects were matched for maternal age, race, sex of the fetus, and severity of the HELLP syndrome. The antepartum platelet count stabilized or increased in 25 of 27 steroid-treated women in contrast to 0 of 15 control women (p <0.00001). In comparison to control patients, LDH serum concentrations in steroid-treated patients stabilized or decreased and the SGOT/AST and SGPT/ALT stabilized or decreased during therapy (p < 0.005). The interval from delivery to platelet nadir in patients with Class III HELLP syndrome was shorter in the steroid-treated group (p<0.008) than in untreated patients.  相似文献   
147.
148.
Of all the causes of eye injury, gunshot has recently been cited as resulting in the highest rate of blindness and the lowest rate of visual recovery. Many of these cases are hunting accidents in which safety glasses could have prevented or lessened ocular damage. To evaluate the effectiveness of various types of safety glasses, we fired a Remington automatic shotgun at mannequin heads fitted with one of four types of safety lenses. From a distance of 10 yards, only polycarbonate lenses provided even partial protection. At 30 yards, polycarbonate and heat-treated lenses provided the best protection, whereas chemically treated and CR39 lenses provided significantly less protection. We recommend that hunters using shotguns in areas of poor visibility wear widely available polycarbonate safety glasses as well as "hunter's orange" to minimize their risk of devastating ocular gunshot injury.  相似文献   
149.
Although an estimated 1 million Americans suffer ocular injuries each year, the setting of injury and its prognostic implications have not been closely examined. Using data compiled by the Eye Injury Registry of Alabama (EIRA) from 514 cases of serious eye injury, we examined the demographics and prognosis of ocular injury by setting of injury. Work-related injuries accounted for only 28% of total injuries, and injuries occurring at home accounted for 27%, followed by situations related to recreation (25%), assault (11%), travel (5%), and "other" (school, unknown, etc) (4%). The poorest initial vision, poorest final vision, and highest rate of enucleation occurred in patients injured by assault, whereas the lowest rate of enucleation and loss of light perception was found in patients who had work-related injuries. Patients in the "other" category had the highest rate of return to 20/100 or better vision.  相似文献   
150.
A J Comerota  G J Stewart  P D Alburger  K Smalley  J V White 《Surgery》1989,106(2):301-8: discussion 308-9
Intraoperative venodilation in veins distant from the site of operation has been shown to occur in animals and has been directly correlated with focal venous endothelial damage. This exposure of subendothelial collagen could serve as initiation sites for thrombus formation. This study tests the hypothesis that human beings (1) significant operative venodilation occurs and that it correlates with postoperative deep venous thrombosis (DVT); (2) operative venodilation can be pharmacologically controlled; and (3) this control reduces the incidence of postoperative DVT. Twenty-one patients undergoing total hip replacement had their contralateral cephalic vein continuously monitored with modified ultrasonographic instrumentation, with a continuous on-line recorder graphing venous diameter. Patients were randomly assigned to receive 0.5 mg of dihydroergotamine and 5000 U of heparin (DHE/Hep) for prophylaxis or placebo, with investigators "blinded" Postoperatively, all patients underwent ascending phlebography. Patients in whom postoperative DVT developed (11) had a mean operative venodilation of 28.9% +/- 3.93%, and those in whom DVT did not develop (10) had a mean venodilation of 11.6% +/- 1.55% (p = 0.001). Only 17% (2/12) dilating less than 20% baseline diameter had DVT compared with 100% (9/9) dilating greater than 20% of baseline diameter (p = 0.002). Patients receiving venotonic agent DHE had significantly less venodilation and DVT (p less than 0.001) compared with patients receiving the placebo. Patients who had DVT and whose veins dilated greater than 20% were older than patients who did not have DVT and whose veins minimally dilated: p = 0.04 and p = 0.07, respectively. Although there was a trend toward increased venoconstriction in patients receiving DHE/Hep (p = 0.09), there was no correlation of venoconstriction with ultimate thrombotic outcome. Maximal venodilation occurs during handling of soft tissue (muscle), and this occurs significantly sooner than maximal venoconstriction, which occurs during bone manipulation. We conclude that excessive operative venodilation is a new and important etiologic factor that leads to postoperative DVT. Operative venodilation can be pharmacologically controlled with the venotonic agent DHE. The combination DHE/Hep reduces postoperative DVT by the reduction of operative venodilation in the presence of low doses of an anticoagulant. These findings offer a new approach for predicting postoperative DVT and an object rationale for developing effective prophylaxis.  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