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   277817篇
  免费   22433篇
  国内免费   6498篇
耳鼻咽喉   2046篇
儿科学   4299篇
妇产科学   3963篇
基础医学   29750篇
口腔科学   5567篇
临床医学   26640篇
内科学   33717篇
皮肤病学   2764篇
神经病学   23787篇
特种医学   26821篇
外国民族医学   16篇
外科学   21840篇
综合类   33938篇
现状与发展   25篇
一般理论   10篇
预防医学   22856篇
眼科学   3260篇
药学   30198篇
  88篇
中国医学   17179篇
肿瘤学   17984篇
  2024年   622篇
  2023年   3909篇
  2022年   7720篇
  2021年   11633篇
  2020年   9929篇
  2019年   9763篇
  2018年   9776篇
  2017年   10516篇
  2016年   10488篇
  2015年   9829篇
  2014年   13979篇
  2013年   17426篇
  2012年   14569篇
  2011年   16953篇
  2010年   11859篇
  2009年   11964篇
  2008年   13676篇
  2007年   14517篇
  2006年   13514篇
  2005年   12262篇
  2004年   10376篇
  2003年   9219篇
  2002年   7278篇
  2001年   6650篇
  2000年   5523篇
  1999年   4690篇
  1998年   3818篇
  1997年   3908篇
  1996年   3475篇
  1995年   3116篇
  1994年   2955篇
  1993年   2408篇
  1992年   2174篇
  1991年   1974篇
  1990年   1655篇
  1989年   1354篇
  1988年   1283篇
  1987年   1131篇
  1986年   1004篇
  1985年   1369篇
  1984年   1092篇
  1983年   816篇
  1982年   840篇
  1981年   693篇
  1980年   671篇
  1979年   523篇
  1978年   329篇
  1977年   290篇
  1976年   267篇
  1975年   203篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
92.
93.
The aim of this paper is to present a method to produce macroporous thin membranes made of poly (ethyl acrylate-co-hydroxyethyl acrylate) copolymer network with varying cross-linking density for cell transplantation and prosthesis fabrication. The manufacture process is based on template techniques and anisotropic pore collapse. Pore collapse was produced by swelling the membrane in acetone and subsequently drying and changing the solvent by water to produce 100 microns thick porous membranes. These very thin membranes are porous enough to hold cells to be transplanted to the organism or to be colonized by ingrowth from neighboring tissues in the organism, and they present sufficient tearing stress to be sutured with surgical thread. The obtained pore morphology was observed by Scanning Electron Microscope, and confocal laser microscopy. Mechanical properties were characterized by stress–strain experiments in tension and tearing strength measurements. Morphology and mechanical properties were related to the different initial thickness of the scaffold and the cross-linking density of the polymer network. Seeding efficiency and proliferation of mesenchymal stem cells inside the pore structure were determined at 2 h, 1, 7, 14 and 21 days from seeding.  相似文献   
94.
95.
96.
97.
《Drug discovery today》2022,27(6):1733-1742
Compounds that exhibit assay interference or undesirable mechanisms of bioactivity are routinely encountered in assays at various stages of drug discovery. We observed that assays for the investigation of thiol-reactive and redox-active compounds have not been collected in a comprehensive review. Here, we review these assays and subject them to experimental optimization to improve their reliability. We demonstrate the usefulness of our assay cascade by assaying a library of bioactive compounds, chemical probes, and a set of approved drugs. These high-throughput assays should complement the array of wet-lab and in silico assays during the initial stages of hit discovery campaigns to pursue only hit compounds with tractable mechanisms of action.  相似文献   
98.
目的 探讨糖尿病前期的中医证型及证素分布特点。方法 检索中国知网、万方及维普三大数据库中收录的自建库以来有关糖尿病前期证型的临床研究文献,对中医证型进行规范整理,建立数据库,提取证素,运用数据挖掘技术中的关联分析、聚类分析探究证素分布规律。结果 共纳入10篇文献,总有效病例1620例,证型经规范处理后整理为18个,主要证型为脾虚痰湿证。共提取证素13个,主要病位证素为脾,主要病性证素为气虚、湿和痰,关联分析显示脾—湿支持度和置信度最高,聚类分析结果可得到3个聚类组。结论 糖尿病前期病位在脾,气虚、脾、痰、湿是常见证素,临床诊治糖尿病前期应注重从脾论治,需辨证施治。  相似文献   
99.
BackgroundIn patients with melanoma, sentinel lymph node (SLN) status is pivotal for treatment decisions. Current routine for SLN detection combines Technetium99m (Tc99) lymphoscintigraphy and blue dye (BD). The primary aim of this study was to examine the feasibility of using a low dose of superparamagnetic iron oxide (SPIO) injected intracutaneously to detect and identify the SLN, and the secondary aim was to investigate if a low dose of SPIO would enable a preoperative MRI-evaluation of SLN status.MethodsPatients with melanoma of the extremities were eligible. Before surgery, a baseline MRI of the nodal basin was followed by an injection of a low dose (0.02–0.5 mL) of SPIO and then a second MRI (SPIO-MRI). Tc99 and BD was used in parallel and all nodes with a superparamagnetic and/or radioactive signal were harvested and analyzed.ResultsFifteen patients were included and the SLNB procedure was successful in all patients (27 SLNs removed). All superparamagnetic SLNs were visualized by MRI corresponding to the same nodes on scintigraphy. Micrometastatic deposits were identified in four SLNs taken from three patients, and SPIO-MRI correctly predicted two of the metastases. There was an association between MRI artefacts in the lymph node and the dose SPIO given.DiscussionIt is feasible to detect SLN in patients with melanoma using a low dose of SPIO injected intracutaneously compared with the standard dual technique. A low dose of SPIO reduces the lymph node MRI artefacts, opening up for a non-invasive assessment of SLN status in patients with cancer.  相似文献   
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