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   415篇
  免费   31篇
  国内免费   105篇
儿科学   27篇
妇产科学   5篇
基础医学   43篇
口腔科学   34篇
临床医学   102篇
内科学   99篇
皮肤病学   6篇
神经病学   8篇
特种医学   69篇
外科学   23篇
综合类   37篇
预防医学   10篇
眼科学   5篇
药学   51篇
中国医学   1篇
肿瘤学   31篇
  2021年   4篇
  2020年   2篇
  2019年   3篇
  2018年   5篇
  2017年   6篇
  2016年   7篇
  2015年   11篇
  2014年   6篇
  2013年   16篇
  2012年   6篇
  2011年   12篇
  2010年   17篇
  2009年   17篇
  2008年   4篇
  2007年   58篇
  2006年   11篇
  2005年   24篇
  2004年   12篇
  2003年   9篇
  2002年   13篇
  2001年   5篇
  2000年   11篇
  1999年   6篇
  1998年   45篇
  1997年   35篇
  1996年   38篇
  1995年   17篇
  1994年   22篇
  1993年   14篇
  1992年   10篇
  1991年   3篇
  1990年   11篇
  1989年   13篇
  1988年   14篇
  1987年   12篇
  1986年   12篇
  1985年   5篇
  1984年   3篇
  1982年   3篇
  1981年   4篇
  1980年   3篇
  1977年   4篇
  1976年   6篇
  1975年   3篇
  1974年   1篇
  1973年   1篇
  1972年   1篇
  1971年   1篇
  1965年   1篇
  1960年   1篇
排序方式: 共有551条查询结果,搜索用时 31 毫秒
111.

Background  

Because of a high cardiovascular disease (CVD) risk in people with Familial Hypercholesterolemia (FH), early prevention of cardiovascular disease is important for health gain and cost reduction. This project focuses on the development and evaluation of an innovative intervention aiming to reduce CVD risk by promoting a healthy lifestyle among people with FH.  相似文献   
112.
The prevalence of overweight and obesity and their health-related problems have been increasing.Obesity is increasingly recognized as a risk factor in different types of cancer in humans.The mechanisms supporting the link between obesity and cancer development have not been fully understood.Leptin,a circulating cytokine produced by adipocytes,may influence prostate cancer(PCa)progression in different ways.Body mass index seems to be an unreliable predictor for the development of PCa,but its influence on progression and poor oncological outcomes seems to be clear.Given the fact that abdominal fat is the most metabolically active fat,with different metabolic and paracrine effects,related anthropometric measurements may lead to a better estimation of PCa risk.Metabolically active periprostatic abdominal fat may also play an important role in releasing cytokines and growth factors that may promote tumor cell proliferation or even create a favorable environment for aggressive tumor biology.Different imaging measurements,e.g.,periprostatic adipose tissue(PPAT)thickness,may be significant predictors of PCa.Several genes in the PPAT of obese men have been identified to contribute to chronic immuno-inflammatory responses which eventually lead to cell cycle alterationwith oncological potential.In vitro studies showed the importance of PCa and its interaction with its microenvironment particularly in patients with aggressive PCa.Different types of cytokines,such as interleukin-6,may promote a tumorigenic microenvironment.This article endeavors to review the current literature on the association of PPAT with aggressive tumor biology in PCa.  相似文献   
113.
Effect of magnification on locating the MB2 canal in maxillary molars   总被引:16,自引:0,他引:16  
The purpose of this study was to determine if the surgical operating microscope and/or dental loupes could enhance the practitioner's ability to locate the second mesiobuccal canal (MB2) canal of maxillary molars in an in vivo, clinical setting. The participating endodontists documented 312 cases of root canal therapy on maxillary first and second molars. Participants that used the microscope or dental loupes located the MB2 canal with a frequency of 57.4% and 55.3%, respectively. Those using no magnification located the MB2 canal with a frequency of 18.2%. When no magnification was used, significantly fewer MB2 canals were located based by Chi-square analysis at p < 0.01. There was no significant difference between the use of the microscope and dental loupes in the frequency of locating the MB2 canal. When the maxillary first molars were considered separately, the frequency of MB2 canal detection for the microscope, dental loupes, and no magnification groups was 71.1%, 62.5%, and 17.2%, respectively. The results of this study show that the use of magnification in combined groups leads to a MB2 detection rate approximately three times that of the nonmagnification group and that the use of no magnification results in the location of significantly fewer MB2 canals. Based on these results, more emphasis should be placed on the importance of using magnification for locating the MB2 canal.  相似文献   
114.
Objectives.?To determine whether growth velocity parameters derived from routine prenatal ultrasound measurements at first, second and third trimester can identify normal growth at term as well as late-onset growth abnormalities.

Material and methods.?Longitudinal study of fetal growth in normal singleton pregnancies with three normal ultrasound examinations and delivered at term. Fetuses were classified into 3 groups (?<?10th percentile, 10–90th percentile, >?90th percentile) based on birth weight. Multiple regression on birth weight classification was used to build up a prediction equation of fetal growth potential (FGP) based on fetal biometry and fetal growth velocity parameters between ultrasound examinations. Best cut-off value for FGP predicting growth restriction and macrosomia were defined.

Results.?356 pregnancies were included. Fetal biometry growth velocities between examinations were calculated for all measurements. Using best cut-off values, the estimated sensitivity, specificity and odds ratio were: 60% [44;74], 91%[89;92] and 14.55 [6.30;33.98] and 53% [36;69], 89%[88;91] and 10 [4.27;23.49] for the prediction of growth restriction and macrosomia, respectively.

Discussion.?Fetal growth potential can be derived and calculated from standard ultrasound measurements. It can improve identification of these fetuses at risk for late-onset growth abnormalities and their related morbidity.  相似文献   
115.
AIM: To assess the prevalence and location of advanced neoplasia in patients undergoing colonoscopy, and to compare the yield per indication. METHODS: In a multicenter colonoscopy survey (n = 18 hospitals) in the Amsterdam area (Northern Holland), data of all colonoscopies performed during a three month period in 2005 were analyzed. The location and the histological features of all colonic neoplasia were recorded. The prevalence and the distribution of advanced colorectal neoplasia and differences in yield between indication clusters were evaluated. Advanced neoplasm was defined as adenoma 〉 10 mm in size, with 〉 25% villous features or with high-grade dysplasia or cancer. RESULTS: A total of 4623 eligible patients underwent a total colonoscopy. The prevalence of advanced neoplasia was 13%, with 281 (6%) adenocarcinomas and 342 (7%) advanced adenomas. Sixty-seven percent and 33% of advanced neoplasia were located in the distal and proximal colon, respectively. Of all patients with right-sided advanced neoplasia (n = 228), 51% had a normal distal colon, whereas 27% had a synchronous distal adenoma. Ten percent of all colonoscopies were performed in asymptomatic patients, 7% of whom had advanced neoplasia. In the respective procedure indication clusters, the prevalence of rightsided advanced neoplasia ranged from 11%-57%. CONCLUSION: One out of every 7-8 colonoscopies yielded an advanced colorectal neoplasm. Colonoscopy is warranted for the evaluation of both symptomatic and asymptomatic patients.  相似文献   
116.
目的探讨足部软组织肿瘤扩大切除术后出现缺损的修复方法.方法自1989年10月~2001年10月,应用胫后血管逆行岛状皮瓣修复15例足部软组织肿瘤扩大切除术后的缺损.结果15例患者随访12~84个月,平均38个月.胫后血管逆性岛状皮瓣完全成活,并且无局部复发.结论小腿内侧胫后血管逆行岛状皮瓣修复足部肿瘤性软组织缺损是理想的选择.具有就近取材、皮肤色泽结构相似,操作简单的特点.  相似文献   
117.
王瑞  安宁  付力军 《医学争鸣》2000,21(4):508-508
1 病例报告 男 ,71岁 ,因排尿困难于 1999- 0 9- 0 4入院 .B超确诊前列腺增生 5 a,既往无高血压、心脏病及心率失常史 .查体 :Bp17/ 10 k Pa,心界不大 ,心率 6 2次· min- 1 ,心律齐 .下腹部可触及涨大的膀胱 ,约耻骨上 4指 .入院时 ECG正常 .肝肾功能无异常 ,确诊前列腺增生伴急性尿潴留 .首先予导尿 ,导出尿液约 90 0 m L,之后 im乙稀雌酚 1mg,2 h后患者突发心慌、胸闷、气短、心前区疼痛 .发现患者大汗BP12 /6 k Pa,P110次· min- 1 ,R2 8次· min- 1 ,心率绝对不齐 ,脉搏明显短促 ,两肺底可闻及湿性罗音及哮鸣音 ,ECG示房颤 ,心…  相似文献   
118.
薄层扫描法测定黄芪生脉颗粒中黄芪甲甙含量   总被引:5,自引:0,他引:5  
目的:制订黄芪生脉颗粒中黄芪甲甙含量测定方法。方法:双波长薄层扫描法,经乙酰洗涤、正丁醇提取和D101大乳吸附树脂柱层析法制备样品,以氯仿-甲醇-水(13:7:2)下层液为展开剂,检测波长为510nm,参比波长为700nm。结果:加标回收率平均为98.7%(RSD=2.0%,n=6),标准曲线r=0.9966,重复性RSD=1.4%(n=5),精密度RSD=2.0%(n=6)。结论:方法稳定、可靠  相似文献   
119.
灯盏花素对豚鼠单一心室肌细胞ICa的抑制作用   总被引:25,自引:0,他引:25  
目的:观察灯盏花素对豚鼠单一心室肌细胞钙离子电流(ICa)的影响。方法:应用全细胞膜片钳制技术。结果:灯盏花素能明显抑制心室肌细胞的Ca^2+通道,使ICa减小。此作用有明显的电压依赖性。在峰电流电压下作用最明显,而对其反转电位无明显影响。在指令电位0mV时,0.5mg%灯盏花素使ICa减小5.4%,1mg%灯盏花素使ICa减小22.9%(P〈0.01),2mg%灯盏花素使ICa减小45.0%(P  相似文献   
120.
为了寻找毒性低、增敏作用强的乏氧细胞放射增敏剂,设计并合成了一系列5-溴-,5-甲基-,和5-未取代的3-硝基-1,2,4-三唑-1-乙酰胺类化合物,用HeLaS3细胞进行了体外试验。结果表明5-溴取代衍生物的增敏作用强于相应的5-甲基-或5-未取代的硝基三唑衍生物,但是它们的毒性亦增大。修饰1位乙酰胺侧链也可以改变化合物的增敏作用和亲脂性。在所测定的化合物中TA-101[2-(3-硝基-1-三唑基)乙酰胺]由于有高的增敏作用和低亲脂性,可能是一个有希望的放射增敏剂。  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