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   56309篇
  免费   5295篇
  国内免费   4643篇
耳鼻咽喉   557篇
儿科学   511篇
妇产科学   527篇
基础医学   6524篇
口腔科学   827篇
临床医学   7843篇
内科学   8097篇
皮肤病学   456篇
神经病学   2993篇
特种医学   2146篇
外国民族医学   44篇
外科学   5424篇
综合类   10175篇
现状与发展   7篇
一般理论   5篇
预防医学   3831篇
眼科学   1419篇
药学   6253篇
  64篇
中国医学   3599篇
肿瘤学   4945篇
  2024年   184篇
  2023年   920篇
  2022年   2363篇
  2021年   2823篇
  2020年   2194篇
  2019年   1925篇
  2018年   2023篇
  2017年   1778篇
  2016年   1738篇
  2015年   2708篇
  2014年   3132篇
  2013年   2651篇
  2012年   4047篇
  2011年   4369篇
  2010年   2794篇
  2009年   2110篇
  2008年   2788篇
  2007年   2876篇
  2006年   2909篇
  2005年   2710篇
  2004年   2063篇
  2003年   2283篇
  2002年   2008篇
  2001年   1746篇
  2000年   1498篇
  1999年   1401篇
  1998年   1020篇
  1997年   927篇
  1996年   674篇
  1995年   689篇
  1994年   597篇
  1993年   300篇
  1992年   399篇
  1991年   336篇
  1990年   265篇
  1989年   265篇
  1988年   192篇
  1987年   153篇
  1986年   128篇
  1985年   96篇
  1984年   44篇
  1983年   36篇
  1982年   25篇
  1981年   25篇
  1980年   19篇
  1979年   12篇
  1978年   2篇
  1977年   1篇
  1976年   1篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
利用仿生化学的原理,本文设计并合成了两个儿茶酚胺类和两个羟基吡啶酮类八配位的螯合剂,初步动物试验表明,具有较强的钚促排能力。  相似文献   
22.
本文报告了两例脊髓萎缩,并结合文献复习讨论了该病的好发部位、病因、临床表现、诊断和治疗。脊髓萎缩的病因多为继发性,也可为特发性。根据临床表现结合脊髓CT造影及MRI检查,可以明确诊断。  相似文献   
23.
病理性近视眼的研究进展   总被引:5,自引:4,他引:1  
通过复习近年来相关文献,对近视眼发生发展机制与形觉剥夺之间的关系进行综合评述。认为近视眼的发生及眼轴延长与形觉剥夺有一定关系,深入研究其相关机制,对近视眼的早期防治具有重要意义。  相似文献   
24.
病人生理监测仪是临床医学的主要仪器,由于涉及技术流程的功能定位不同,功能需求也就不同,其功能配置也就有所不同。从生理监测仪相关应用领域的分解技术功能定位出发,讨论装备管理的功能配置问题。  相似文献   
25.
A genome-wide screen was conducted using a large white sample to identify QTLs for FNCS geometry. We found significant linkage of FNCS parameters to 20q12 and Xq25, plus significant epistatic interactions and sex-specific QTLs influencing FNCS geometry variation. INTRODUCTION: Bone geometry, a highly heritable trait, is a critical component of bone strength that significantly determines osteoporotic fracture risk. Specifically, femoral neck cross-sectional (FNCS) geometry is significantly associated with hip fracture risk as well as genetic factors. However, genetic research in this respect is still in its infancy. MATERIALS AND METHODS: To identify the underlying genomic regions influencing FNCS variables, we performed a remarkably large-scale whole genome linkage scan involving 3998 individuals from 434 pedigrees for four FNCS geometry parameters, namely buckling ratio (BR), cross-sectional area (CSA), cortical thickness (CT), and section modulus (Z). The major statistical approach adopted is the variance component method implemented in SOLAR. RESULTS: Significant linkage evidence (threshold LOD = 3.72 after correction for tests of multiple phenotypes) was found in the regions of 20q12 and Xq25 for CT (LOD = 4.28 and 3.90, respectively). We also identified eight suggestive linkage signals (threshold LOD = 2.31 after correction for multiple tests) for the respective geometry traits. The above findings were supported by principal component linkage analysis. Of them, 20q12 was of particular interest because it was linked to multiple FNCS geometry traits and significantly interacted with five other genomic loci to influence CSA variation. The effects of 20q12 on FNCS geometry were present in both male and female subgroups. Subgroup analysis also revealed the presence of sex-specific quantitative trait loci (QTLs) for FNCS traits in the regions such as 2p14, 3q26, 7q21 and 15q21. CONCLUSIONS: Our findings laid a foundation for further replication and fine-mapping studies as well as for positional and functional candidate gene studies, aiming at eventually finding the causal genetic variants and hidden mechanisms concerning FNCS geometry variation and the associated hip fractures.  相似文献   
26.
IN T R O D U C T IO NSuperoxide dism utase (SO D )is an im portantendogenous free radica scavenger, itelim inates superoxide anion free radicals through dis proportionation, and itprotects the nerve cells in the process ofcere bralischem ia reperfusion in…  相似文献   
27.
The effects of combined use of earthworm extract(912)and HpD-laser on the produc-tion of reactive oxygen and the biosynthesis of DNA in S_(180) tumor cells were studied throughchemiluminescence measurement and[~3H]-TdR incorporation assay.The results showed that as com-pared with the control,the intensity of chemiluminescence emitted by tumor cells treatedsimultaneously with 912 and HpD-laser was enhanced more than ten-folds,while that treated with912 or HpD-laser alone was increased only 2~4 folds.The[~3H]-TdR incorporation into tumorcells of the former group was inhibited upto 74.1%,and that of the latter groups decreased onlyby 42.2% and 40.0%,respectively.In accordance with these biochemical changes,the ultrastructuraldamage of tumor cells of the former,combinedly treated group appeared to be the most serious.This suggests an additive effect of 912 with HpD-laser on tumor cells.In addition,if free radicalscavengers,such as catalase and superoxide dismutase,were added to the reaction systembefore chemiluminescence assay,the luminescent enhancement effect mentioned above was dramaticallyalleviated,implying the presence of O_2~ and H_2O_2 in the system.Therefore,as to the toxic effecton tumor cells,912 and HpD-laser are not only additive in efficiency,but also similar in theunderlying mechanism of action.  相似文献   
28.
29.
采用间接ELISA检测23名肾移植受者血清巨细胞病毒(CMV)抗体,共检出18名(78%)活动性CMV感染,其中10名(44%)为原发性感染。结果证实CMV-IgE和-IgA具有较好的血清学诊断价值,优于CMV-IgM。  相似文献   
30.
Tumors from 40 patients and 7 established human xenograft tumor lines were grown in three-dimensional histoculture. A Viable-Cell-Index (VCI) based on fluorescent dyes and Growth Fraction Index (GFI) based on [3H]thymidine incorporation were measured by confocal microscopy and histological autoradiography, respectively, after treatment with cytotoxic agents. Chemosensitivity in vitro with the two methods was correlated with chemosensitivity of the same set of human xenografted tumor lines grown in nude mice. The percent accuracy of in vitro to in vivo correlation with VCI (73%) was higher than GFI (63%). The number of false positives with VCI was 12.1% (4/33), and with GFI was 31.3% (10/32). The results thus indicated that in vitro histoculture with fluorescent vital-dye end-points to measure cell viability is of potential use to determine tumor chemosensitivity.  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