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   56418篇
  免费   5303篇
  国内免费   4667篇
耳鼻咽喉   555篇
儿科学   514篇
妇产科学   528篇
基础医学   6520篇
口腔科学   836篇
临床医学   7867篇
内科学   8130篇
皮肤病学   460篇
神经病学   2992篇
特种医学   2178篇
外国民族医学   44篇
外科学   5431篇
综合类   10180篇
现状与发展   7篇
一般理论   5篇
预防医学   3838篇
眼科学   1419篇
药学   6279篇
  64篇
中国医学   3596篇
肿瘤学   4945篇
  2024年   184篇
  2023年   919篇
  2022年   2360篇
  2021年   2819篇
  2020年   2195篇
  2019年   1918篇
  2018年   2022篇
  2017年   1779篇
  2016年   1739篇
  2015年   2714篇
  2014年   3131篇
  2013年   2653篇
  2012年   4047篇
  2011年   4369篇
  2010年   2799篇
  2009年   2122篇
  2008年   2788篇
  2007年   2895篇
  2006年   2914篇
  2005年   2712篇
  2004年   2064篇
  2003年   2284篇
  2002年   2006篇
  2001年   1751篇
  2000年   1503篇
  1999年   1403篇
  1998年   1027篇
  1997年   938篇
  1996年   680篇
  1995年   691篇
  1994年   605篇
  1993年   307篇
  1992年   405篇
  1991年   339篇
  1990年   265篇
  1989年   270篇
  1988年   198篇
  1987年   156篇
  1986年   129篇
  1985年   102篇
  1984年   47篇
  1983年   39篇
  1982年   30篇
  1981年   28篇
  1980年   19篇
  1979年   12篇
  1978年   5篇
  1977年   2篇
  1976年   3篇
  1975年   1篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
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   
92.
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   
93.
Dynamic observation on thyroid function in severe head injury.   总被引:1,自引:0,他引:1  
The dynamic changes of thyroid hormone levels in patients with severe head injury were observed. The results showed that the serum thyroid hormone levels changed rapidly within several hours after the injury and the mean levels of serum total T3 and T4 (TT3, TT4) decreased while high reverse triiodothyronine (rT3) increased significantly. Serum TT3, TT4 and rT3 levels returned to normal gradually in 2 to 3 weeks after the injury in the surviving group, whereas serum total T4 gradually declined and rT3 steadily increased in the fatal group. The mean levels of serum TSH remained unchanged in both groups. Therefore, the use of the levels of serum thyroid hormones as adjuvant indices can be helpful in making pertinent judgements of the severity and prognosis of severe head injuries.
  相似文献   
94.
Intravenous leiomyomatosis is a rare uterineneoplasm, histologically characterized by nodularmasses of benign smooth muscle growing withinthe uterine and pelvic veins. The entity has ty-pical gross and microscopic features. A case of intravenous leiomyomatosisassociated with uterine leiomyoma, adenomyosisand early pregnancy was reported. The condi-tion was recognized during surgery for uterinefibroids. This is, to our knowledge, the thirdcase of intravenOUs leiomyomatosis associatedwith pregnancy so far reported.  相似文献   
95.
本文采用热变性温度法和液相复性速率法对—轻型特征及血清学反应相似米克戴德军团菌(Lm)的菌株进行了测定,结果表明该菌与标准Lm(C DC株)的DNA G Cmol%相差3.45%,与标准Lm(C DC株)的DNA同源性达81.99%,根据伯杰细菌鉴定手册(1984),可判定该菌株与标准Lm(C DC株)为遗传型一致的类群,即从遗传学角度证明该菌为Lm。  相似文献   
96.
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   
97.
98.
本文通过对医院药事管理委员会的组织形式以及在医院药学事业中的特殊地位、工作任务、工作职责及职能效应的初步探讨,指出医院药事管理委员会在发展和建设医院药学事业中具有十三种职能、七大效应。认为加强医院药事管理委员会建设,是发展医院药学事业和保证医院药品质量的一种好方式。  相似文献   
99.
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   
100.
目的 :观察贾第虫病的临床表现及甲硝唑对贾第虫病的治疗作用。方法 :用甲硝唑治疗 42例贾第虫病患者 ,剂量为 0 .4g,日 3次 ,连服 7~ 10 d为一疗程 ,其中服 1个疗程的有 3 5例 ,服 2个疗程的有 5例 ,服 3个疗程的有 2例。结果 :经治疗后 ,全部患者的症状如腹泻及 (或 )腹痛等胃肠道症状均消失 ,粪检结果恢复正常。患者服药期间的不良反应轻 ,仅有轻微的胃肠道反应 ,如恶心、厌食等。结论 :甲硝唑治疗贾第虫病具有疗效好、耐受性好的优点  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