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   3496篇
  免费   280篇
  国内免费   114篇
耳鼻咽喉   11篇
儿科学   46篇
妇产科学   21篇
基础医学   196篇
口腔科学   31篇
临床医学   334篇
内科学   238篇
皮肤病学   13篇
神经病学   102篇
特种医学   316篇
外科学   451篇
综合类   514篇
预防医学   171篇
眼科学   58篇
药学   833篇
  1篇
中国医学   301篇
肿瘤学   253篇
  2024年   39篇
  2023年   63篇
  2022年   75篇
  2021年   99篇
  2020年   104篇
  2019年   112篇
  2018年   101篇
  2017年   110篇
  2016年   150篇
  2015年   120篇
  2014年   250篇
  2013年   235篇
  2012年   226篇
  2011年   228篇
  2010年   166篇
  2009年   177篇
  2008年   162篇
  2007年   117篇
  2006年   142篇
  2005年   143篇
  2004年   86篇
  2003年   102篇
  2002年   83篇
  2001年   65篇
  2000年   65篇
  1999年   60篇
  1998年   68篇
  1997年   51篇
  1996年   56篇
  1995年   38篇
  1994年   43篇
  1993年   39篇
  1992年   33篇
  1991年   33篇
  1990年   31篇
  1989年   25篇
  1988年   24篇
  1987年   20篇
  1986年   22篇
  1985年   24篇
  1984年   15篇
  1983年   7篇
  1982年   22篇
  1981年   10篇
  1980年   10篇
  1979年   8篇
  1977年   6篇
  1976年   5篇
  1975年   8篇
  1973年   4篇
排序方式: 共有3890条查询结果,搜索用时 0 毫秒
81.
The case is described of a 40 year old man with delusions and hallucinations, who at the start of this study was taking doses of neuroleptic medication greatly in excess of those that have been demonstrated to be optimally effective. Over 48 weeks, using PQ methods and detailed interviewing, his progress was charted as the medication was reduced to more appropriate levels. Across this change, his delusional beliefs remained unchanged, but there were substantial reductions in auditory hallucinations, as well as in hopelessness and anxiety. The case has implications for concepts of therapy in the psychoses and for the methodology of therapy studies. It also illustrates possible benefits of using PQ or other self-assessment methods as a means of calibrating therapy and perhaps enhancing compliance. © 1998 John Wiley & Sons, Ltd.  相似文献   
82.
83.
Over the past 100 years Drosophila has been developed into an outstanding model system for the study of evolutionary processes. A fascinating aspect of evolution is the differentiation of sex chromosomes. Organisms with highly differentiated sex chromosomes, such as the mammalian X and Y, must compensate for the imbalance in gene dosage that this creates. The need to adjust the expression of sex-linked genes is a potent force driving the rise of regulatory mechanisms that act on an entire chromosome. This review will contrast the process of dosage compensation in Drosophila with the divergent strategies adopted by other model organisms. While the machinery of sex chromosome compensation is different in each instance, all share the ability to direct chromatin modifications to an entire chromosome. This review will also explore the idea that chromosome-targeting systems are sometimes adapted for other purposes. This appears the likely source of a chromosome-wide targeting system displayed by the Drosophila fourth chromosome.  相似文献   
84.
目的研究比较不同浓度、剂量,等比重布比卡因对产妇的麻醉效果及新生儿的影响,为临床麻醉提供参考依据。方法选择ASAⅠ~Ⅱ级初次足月妊娠拟择期剖宫产手术孕妇80例,随机分为A、B二组,每组各40例。均在左侧卧位下行腰-硬联合穿刺,L2-3进针,见脑脊液外流后,针斜面向下注入等比重布比卡因:A组:8mg(0·5%,1·6ml;配法:0·75%布比卡因2ml+脑脊液1ml);B组:9·6mg(0·6%,1·6ml;配法:0·75%布比卡因2ml+脑脊液0·5ml),20s注药完毕。记录麻醉前(基础值)和脊麻注药后1、3、5、7、10、15min各时间点的平均动脉压(MAP)、心率(HR)、脉搏血氧饱合度(SpO2)。测定并记录麻醉起效时间、平面固定时间、最高麻醉平面点(胸,T)、麻醉完全消退时间、下肢阻滞的最大程度、麻醉并发症等。结果A组感觉阻滞起效时间长于B组(69·27±21·48vs52·43±27·61s,P<0·05);两组最高阻滞平面(T4·50±1·44vsT4·10±0·57)及最高阻滞平面的固定时间(7·69±1·36vs7·35±1·22min)相似(P>0·05)。A组麻醉完全消退时间快于B组(218·40±18·57vs256·22±16·72min,P<0·05);Bromage评分A组明显小于B组(2·03±0·68vs2·93±0·21,P<0·05);麻醉后B组低血压发生率明显高于A组(P<0·05)。两组病人的麻醉效果均优,肌松满意。所有新生儿的Apgar评分均在7分以上,无组间差异。结论两组病人均产生了良好的脊麻效果,权衡利弊剖宫产脊麻时应用8mg(0·5%,1·6ml)布比卡因更为安全合理。  相似文献   
85.
86.
为提高诊断X线机的诊断质量,促进放射防护工作的开展,根据"国际辐射单位和测量委员会"(International Commission on Radiological Units and Measurements,ICRU),"国际放射防护委员会"(International Commission on Radiation Protection,ICRP)关于辐射对人体的损害之划分标准,作者对岛津制作所90年代中期生产的XEB150L-20型500mA X线机按照国家规定的要求及有关标准,分别对辐射空气释动能率,半价层,输入量重复性,输出量线性,高对比分辨率,光野与照射野一致性及X线管的焦点等参数进行了测试。分析了测试的数据与结果,并进行了简要的评价。  相似文献   
87.
We developed a database compiling in vivo doses of compounds for various activities in certain animal species. The related database covers almost 100 years of experiments. The conceptual scheme of the database was created using concepts of the entity-relationship modeling principles. Using published references, dosages and their effects on laboratory animals were entered as data. As the next stage of our work, we have started to examine the available literature to information about the experimental dosages of various drugs used in other studies.The database provides various interfaces, including graphical-user interfaces and interfaces for Internet access. The database will be useful as a knowledge infrastructure for researchers who have to perform dose-scan experiments for a specific pharmacological activity. The basic benefit of that knowledge infrastructure is that it will enable virtual pharmacological experiments that will be considerably less expensive than conventional laboratory experiments, because the number of animals used and the number of dose-scan experiments will be greatly reduced. The developed database will also be helpful for new drug development studies and for responding to queries about animal types, drugs used, drug interactions, and results.  相似文献   
88.
89.
Recent genome‐wide association studies identified the common genetic variants in 9p21 were associated with the coronary artery disease (CAD). However, whether this locus could predict the severity of CAD in Chinese Han population is unclear. 499 CAD patients who underwent coronary angiography (CAG) have been enrolled for this study. The single‐nucleotide polymorphisms rs2383207 and rs2383206 in 9p21 were genotyped in 499 CAG cases and 1519 controls in Chinese Han population. The gene dosage of 9p21 was stratified by the degree of vascular lesions and tested for association with the severity of CAD. Rs2383207 and rs2383206 demonstrated significant associations with 2‐vessel and 3‐vessel disease (P = 2.0×10?3 and 1.9×10?4, respectively). GG genotypes of rs2383206 occurred higher proportion of left main trunk (LM) disease (P = 6.0×10?3). GG genotypes of rs2383207 occurred higher proportion of left anterior descending artery disease (LAD) and right CAD (RCA) (P = 2.7×10?6 and 1.6×10?4, respectively). The risk allele G of rs2383207 was associated with severity of CAD estimated by the Gensini score (P = 3.6×10?5). Rs2383207 may strongly influence the development of CAD in Chinese Han population. The gene dosage in 9p21 could predict the severity of CAD.  相似文献   
90.
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