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   9397篇
  免费   588篇
  国内免费   190篇
耳鼻咽喉   206篇
儿科学   66篇
妇产科学   49篇
基础医学   1767篇
口腔科学   169篇
临床医学   883篇
内科学   2283篇
皮肤病学   351篇
神经病学   715篇
特种医学   432篇
外科学   985篇
综合类   66篇
现状与发展   1篇
预防医学   363篇
眼科学   113篇
药学   916篇
中国医学   169篇
肿瘤学   641篇
  2024年   7篇
  2023年   86篇
  2022年   308篇
  2021年   490篇
  2020年   211篇
  2019年   272篇
  2018年   318篇
  2017年   226篇
  2016年   358篇
  2015年   452篇
  2014年   565篇
  2013年   603篇
  2012年   1047篇
  2011年   928篇
  2010年   483篇
  2009年   388篇
  2008年   514篇
  2007年   501篇
  2006年   402篇
  2005年   394篇
  2004年   270篇
  2003年   266篇
  2002年   216篇
  2001年   177篇
  2000年   174篇
  1999年   130篇
  1998年   64篇
  1997年   51篇
  1996年   27篇
  1995年   23篇
  1994年   24篇
  1993年   19篇
  1992年   26篇
  1991年   19篇
  1990年   24篇
  1989年   17篇
  1988年   22篇
  1987年   12篇
  1986年   11篇
  1985年   12篇
  1984年   6篇
  1983年   5篇
  1982年   3篇
  1981年   3篇
  1979年   4篇
  1977年   2篇
  1976年   4篇
  1973年   2篇
  1940年   1篇
  1939年   1篇
排序方式: 共有10000条查询结果,搜索用时 11 毫秒
101.
102.
Silica is the most commonly used oxide encapsulant for passivating fluorescent quantum dots (QDs) against degradable conditions. Such a silica encapsulation has been conventionally implemented via a Stöber or reverse microemulsion process, mostly targeting CdSe-based QDs to date. However, both routes encounter a critical issue of considerable loss in photoluminescence (PL) quantum yield (QY) compared to pristine QDs after silica growth. In this work, we explore the embedment of multishelled InP/ZnSeS/ZnS QDs, whose stability is quite inferior to CdSe counterparts, in a silica matrix by means of a tetramethyl orthosilicate-based, waterless, catalyst-free synthesis. It is revealed that the original QY (80%) of QDs is nearly completely retained in the course of the present silica embedding reaction. The resulting QD–silica composites are then placed in degradable conditions such UV irradiation, high temperature/high humidity, and operation of an on-chip-packaged light-emitting diode (LED) to attest to the efficacy of silica passivation on QD stability. Particularly, the promising results with regard to device efficiency and stability of the on-chip-packaged QD-LED firmly suggest the effectiveness of the present silica embedding strategy in not only maximally retaining QY of QDs but effectively passivating QDs, paving the way for the realization of a highly efficient, robust QD-LED platform.

Silica embedding strategy enabling a nearly full PL retention of the original QY of InP QDs is proposed for the realization of a highly efficient, robust QD-LED platform.  相似文献   
103.
In order to increase the chemical stability of polybenzimidazole (PBI) membrane against the highly oxidizing environment of a vanadium redox flow battery (VRFB), PBI/Nafion hybrid membrane was developed by spray coating a Nafion ionomer onto one surface of the PBI membrane. The acid–base interaction between the sulfonic acid of the Nafion and the benzimidazole of the PBI created a stable interfacial adhesion between the Nafion layer and the PBI layer. The hybrid membrane showed an area resistance of 0.269 Ω cm2 and a very low vanadium permeability of 1.95 × 10−9 cm2 min−1. The Nafion layer protected the PBI from chemical degradation under accelerated oxidizing conditions of 1 M VO2+/5 M H2SO4, and this was subsequently examined in spectroscopic analysis. In the VRFB single cell performance test, the cell with the hybrid membrane showed better energy efficiency than the Nafion cell with 92.66% at 40 mA cm−2 and 78.1% at 100 mA cm−2 with no delamination observed between the Nafion layer and the PBI layer after the test was completed.

Novel polybenzimidazole (PBI)/Nafion hybrid membranes for the VRFB are made by spray coating a Nafion layer to protect PBI from chemical degradation.  相似文献   
104.
105.
Correction for ‘Water-floating nanohybrid films of layered titanate–graphene for sanitization of algae without secondary pollution’ by In Young Kim et al., RSC Adv., 2016, 6, 98528–98535.

In the published paper, the affiliations of Eui-Ho Hwang and Woo-Bin Jin were wrongly designated, and the corrected version is shown below.The Royal Society of Chemistry apologises for these errors and any consequent inconvenience to authors and readers.  相似文献   
106.
Silver sulfide nanoparticles (Ag2S NPs) are currently being explored as infrared active nanomaterials that can provide environmentally stable alternatives to heavy metals such as lead. In this paper, we describe the novel synthesis of Ag2S NPs by using a sonochemistry method and the fabrication of photodetector devices through the integration of Ag2S NPs atop a graphene sheet. We have also synthesized Li-doped Ag2S NPs that exhibited a significantly enhanced photodetector sensitivity via their enhanced absorption ability in the UV-NIR region. First-principles calculations based on a density functional theory formalism indicated that Li-doping produced a dramatic enhancement of NIR photoluminescence of the Ag2S NPs. Finally, high-performance photodetectors based on CVD graphene and Ag2S NPs were demonstrated and investigated; the hybrid photodetectors based on Ag2S NPs and Li-doped Ag2S NPs exhibited a photoresponse of 2723.2 and 4146.0 A W−1 respectively under a light exposure of 0.89 mW cm−2 at 550 nm. Our novel approach represents a promising and effective method for the synthesis of eco-friendly semiconducting NPs for photoelectric devices.

Silver sulfide nanoparticles (Ag2S NPs) are currently being explored as infrared active nanomaterials that can provide environmentally stable alternatives to heavy metals such as lead.  相似文献   
107.
Journal of Thrombosis and Thrombolysis - Antiplatelet agents and statin therapies are widely used in patients with known cardiovascular disease. Plaque rupture (PR) and plaque erosion (PE) are the...  相似文献   
108.
Here, we evaluate the efficacy of the Clo-Sur PAD nonwoven hydrophilic wound dressing (HWD) on hemostasis in an arterial-access site after transradial percutaneous coronary angiography compared with the RadiStop compression device (CD). Eighty patients who had undergone transradial coronary angiography with or without intravascular ultrasound were randomly assigned to the HWD or CD group. The time required to achieve hemostasis was measured, and the incidence of vascular complications was assessed. No significant differences in clinical and procedural characteristics were observed between the HWD group (n = 40) and the CD group (n = 40). A significant reduction in the time required to achieve hemostasis (58.7 +/- 32.6 minutes versus 131.3 +/- 59.1 minutes; p < 0.001) was associated with the use of HWD. The incidence of vascular complications was similar in both groups (5% for HWD versus 2.5% for CD; p = 0.500). No major complications, such as large hematoma or acute radial occlusion, occurred in the HWD group. In conclusion, HWD represents a safe alternative to the compression method. Hemostasis can be achieved more quickly using HWD, with no increase in access site complications, as compared to CD.  相似文献   
109.
A 65-year-old man with hypercholesterolaemia and hypertensionunderwent elective percutaneous coronary intervention (PCI)because of exertional angina. Three sirolimus-eluting stents(Cypher; 3.0  相似文献   
110.
In a canine model of acute occlusion of the left anterior descending artery (LAD), left ventriculography was performed before and immediately after occlusion and also one and three weeks later. Regional left ventricular function was evaluated by the centreline method. Global and regional left ventricular function were significantly depressed immediately after occlusion and showed no significant recovery after one and three weeks, except for a decrease in the paradoxical motion of the LAD territory, which was probably due to stiffening of the infarct area.  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