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   6059篇
  免费   610篇
  国内免费   16篇
耳鼻咽喉   80篇
儿科学   168篇
妇产科学   160篇
基础医学   790篇
口腔科学   170篇
临床医学   750篇
内科学   1385篇
皮肤病学   107篇
神经病学   744篇
特种医学   220篇
外科学   908篇
综合类   34篇
一般理论   2篇
预防医学   351篇
眼科学   66篇
药学   384篇
中国医学   3篇
肿瘤学   363篇
  2023年   90篇
  2022年   71篇
  2021年   373篇
  2020年   175篇
  2019年   270篇
  2018年   318篇
  2017年   216篇
  2016年   190篇
  2015年   246篇
  2014年   301篇
  2013年   264篇
  2012年   464篇
  2011年   427篇
  2010年   226篇
  2009年   179篇
  2008年   310篇
  2007年   257篇
  2006年   234篇
  2005年   231篇
  2004年   205篇
  2003年   163篇
  2002年   177篇
  2001年   87篇
  2000年   91篇
  1999年   88篇
  1998年   39篇
  1997年   26篇
  1996年   27篇
  1995年   27篇
  1994年   27篇
  1993年   24篇
  1992年   77篇
  1991年   75篇
  1990年   61篇
  1989年   53篇
  1988年   48篇
  1987年   45篇
  1986年   34篇
  1985年   42篇
  1984年   24篇
  1983年   24篇
  1982年   24篇
  1981年   20篇
  1979年   19篇
  1978年   25篇
  1976年   22篇
  1975年   18篇
  1974年   21篇
  1973年   22篇
  1967年   16篇
排序方式: 共有6685条查询结果,搜索用时 31 毫秒
91.
92.
Traditional histology relies on processing and physically sectioning either frozen or formalin‐fixed paraffin‐embedded (FFPE) tissue into thin slices (typically 4‐6 μm) prior to staining and viewing on a standard wide‐field microscope. Microscopy using ultraviolet (UV) surface excitation (MUSE) represents a novel alternative microscopy method that works with UV excitation using oblique cis‐illumination, which can generate high‐quality images from the cut surface of fresh or fixed tissue after brief staining, with no requirement for fixation, embedding and histological sectioning of tissue specimens. We examined its potential utility in dermatopathology. Concordance between MUSE images and hematoxylin and eosin (H&E) slides was assessed by the scoring of MUSE images on their suitability for identifying 10 selected epidermal and dermal structures obtained from minimally fixed tissue, including stratum corneum, stratum granulosum, stratum spinosum, stratum basale, nerve, vasculature, collagen and elastin, sweat glands, adipose tissue and inflammatory cells, as well as 4 cases of basal cell carcinoma and 1 case of pseudoxanthoma elasticum deparaffinized out of histology blocks. Our results indicate that MUSE can identify nearly all normal skin structures seen on routine H&E as well as some histopathologic features, and appears promising as a fast, reliable and cost‐effective diagnostic approach in dermatopathology.  相似文献   
93.
94.

Purpose

To assess short- and long-term mortality and rebleeding with endoscopic cyanoacrylate (EC) versus balloon-occluded retrograde transvenous obliteration (BRTO).

Materials and Methods

A retrospective cohort comparison was conducted of 90 EC patients and 71 BRTO patients from 1997 through 2015 with portal hypertension who presented due to endoscopically confirmed bleeding cardiofundal gastric varices. Patients underwent either endoscopic intra-varix injection of 4-carbon-n-butyl-2-cyanoacrylate or sclerosis with sodium tetradecyl sulfate with balloon occlusion for primary variceal treatment.

Results

Seventy-one BRTO patients and 90 EC patients, of whom 89% had cirrhosis and 35% were women, were included, with a respective average Model for End-Stage Liver Disease (MELD) score of 13.4 and 14.4, respectively. Mortality at 6 weeks was 14.4% for EC patients and 13.1% for BRTO patients (Kaplan-Meier/Wilcoxon, P = .85). No long-term mortality difference was observed (Cox hazard ratio [HR] = 0.89, P = .64). Also, 5.1% of EC patients and 3.5% of BRTO patients (Kaplan-Meier/Wilcoxon, P = .62) rebled at 6 weeks, but at 1 year, 22.0% of EC patients and 3.5% of BRTO patients had rebled (Kaplan-Meier/Wilcoxon, P < .01). Lower rates of long-term rebleeding were found with BRTO (Cox HR = 0.25, P = .03). No difference was seen in the rate of new portal hypertensive complications (Cox HR = 1.21, P = .464). However, 16/71 patients who underwent BRTO had simultaneous transjugular intrahepatic portosystemic shunt. Age, sex, MELD score, and presence of cirrhosis were the primary predictors of mortality. One death in the EC group and 5 deaths in the BRTO group were deemed to be procedurally related (chi-square, P = .088).

Conclusions

BRTO is associated with a lower rate of rebleeding but no change in mortality.  相似文献   
95.
Atherosclerotic subclavian artery disease is detected in about 5% of patients referred for coronary artery bypass (CABG) surgery. The internal mammary artery, a branch of the subclavian artery, is the most frequently utilized graft to restore coronary circulation because of its longevity. Stenosis or occlusion of the subclavian artery can cause retrograde blood flow in the ipsilateral internal mammary artery, known as “steal,” compromising coronary circulation supplied by the graft. Steal may be asymptomatic or may result in symptoms of myocardial ischemia. Symptomatic subclavian artery stenosis post bypass is referred to as coronary subclavian steal syndrome post‐CABG. The incidence is not well defined, and the benefits of screening patients referred for CABG are not known. Despite the various modalities available to detect subclavian artery stenosis, current guidelines fail to provide guidance about screening high‐risk patients for this entity. Detection of subclavian artery disease prior to CABG can reduce complications posed by post‐mammary artery graft cardiac ischemia. This review discusses the utility of preoperative subclavian artery screening prior to CABG.  相似文献   
96.
The dopamine transporter (DAT) is responsible for terminating dopamine (DA) signaling and is the primary site of cocaine''s reinforcing actions. Cocaine self-administration has been shown previously to result in changes in cocaine potency at the DAT. To determine whether the DAT changes associated with self-administration are due to differences in intake levels or temporal patterns of cocaine-induced DAT inhibition, we manipulated cocaine access to produce either continuous or intermittent elevations in cocaine brain levels. Long-access (LgA, 6 h) and short-access (ShA, 2 h) continuous self-administration produced similar temporal profiles of cocaine intake that were sustained throughout the session; however, LgA had greater intake. ShA and intermittent-access (IntA, 6 h) produced the same intake, but different temporal profiles, with ‘spiking'' brain levels in IntA compared with constant levels in ShA. IntA consisted of 5-min access periods alternating with 25-min timeouts, which resulted in bursts of high responding followed by periods of no responding. DA release and uptake, as well as the potency of cocaine for DAT inhibition, were assessed by voltammetry in the nucleus accumbens slices following control, IntA, ShA, and LgA self-administration. Continuous-access protocols (LgA and ShA) did not change DA parameters, but the ‘spiking'' protocol (IntA) increased both release and uptake of DA. In addition, high continuous intake (LgA) produced tolerance to cocaine, while ‘spiking'' (IntA) produced sensitization, relative to ShA and naive controls. Thus, intake and pattern can both influence cocaine potency, and tolerance seems to be produced by high intake, while sensitization is produced by intermittent temporal patterns of intake.  相似文献   
97.
The role of law in bioethics is clear. Laws are enforcement tools: they govern which conditions qualify an individual for disability benefits, or what oversight is necessary for clinical trial protocols, or how patent applications for medical devices should be regulated. I initially studied the law in order to enhance my work in bioethics, but in examining how the law works, I have become convinced that the converse opportunity also exists: there are many areas of law that would benefit from greater input from those in the bioethics community.  相似文献   
98.
99.
100.
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