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   434篇
  免费   31篇
耳鼻咽喉   5篇
儿科学   31篇
妇产科学   5篇
基础医学   42篇
口腔科学   36篇
临床医学   50篇
内科学   88篇
皮肤病学   2篇
神经病学   17篇
特种医学   16篇
外科学   63篇
综合类   10篇
预防医学   13篇
眼科学   18篇
药学   39篇
  1篇
肿瘤学   29篇
  2023年   5篇
  2022年   16篇
  2021年   10篇
  2020年   13篇
  2019年   13篇
  2018年   18篇
  2017年   10篇
  2016年   15篇
  2015年   14篇
  2014年   11篇
  2013年   18篇
  2012年   27篇
  2011年   20篇
  2010年   18篇
  2009年   21篇
  2008年   29篇
  2007年   27篇
  2006年   25篇
  2005年   17篇
  2004年   16篇
  2003年   9篇
  2002年   22篇
  2001年   16篇
  2000年   9篇
  1999年   5篇
  1998年   1篇
  1997年   2篇
  1996年   2篇
  1995年   1篇
  1994年   2篇
  1993年   1篇
  1992年   5篇
  1991年   7篇
  1990年   2篇
  1989年   4篇
  1988年   5篇
  1985年   4篇
  1984年   2篇
  1983年   2篇
  1982年   3篇
  1981年   3篇
  1980年   2篇
  1979年   2篇
  1977年   3篇
  1976年   4篇
  1975年   3篇
  1973年   1篇
排序方式: 共有465条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
On the Acylation of Hydroxy- and Mercaptocarboxylic Acid Esters Using the Carbodiimide/Acylation Catalyst Method Acylation of esters of hydroxycarboxylic acids can be carried out easily and in good yields by using the carbodiimide/acylation catalyst method. The reaction has also been applied to dihydroxy- and mercaptocarboxylic acid esters. The compounds formed from certain esters of hydroxycarboxylic acids are unstable to heat and decompose easily to the free carboxylic acid. No racemization is observed when using enantiomeric hydroxycarboxylic acids. Use of racemic carboxylic acids leads to diastereomers, whose 1H-NMR shifts for characteristic protons are different as expected. Five drugs are among the carboxylic acids investigated in this context.  相似文献   
5.
We report a new case of Rubinstein-Taybi syndrome with a hypoplastic right kidney, persistent pulmonary hypertension, and mitral valve regurgitation. Other pertinent features included broad thumbs, broad big toes, syndactyly of the third and fourth fingers bilaterally, beaked nose, broad columella of the nose, patent ductus arteriosus, and motor and mental retardation. The testes were descended. The 3 month old patient had delayed motor and mental development corresponding to a 1 month old infant.  相似文献   
6.
Rectal prolapse in infants and children   总被引:1,自引:0,他引:1  
Rectal prolapse that is intractable to the usual medical therapy was successfully managed without significant complications in 10 patients by simple subcutaneous encirclement of the anus with a heavy nonabsorbable suture, which was in place until the suture was removed or broke after 4 to 6 months. Four patients required two sutures and one needed a third insertion. Since this procedure is simple, has no serious complications, and controls rectal prolapse, it is recommended as the preferred initial surgical treatment of this condition.  相似文献   
7.
Vaccination against smallpox is again considered in order to face a possible bioterrorist threat, but the nature and the level of the immune response needed to protect a person from smallpox after vaccination are not totally understood. Therefore, simple, rapid, and accurate assays to evaluate the immune response to vaccinia virus need to be developed. Neutralization assays are usually considered good predictors of vaccine efficacy and more informative with regard to protection than binding assays. Currently, the presence of neutralizing antibodies to vaccinia virus is measured using a plaque reduction neutralization test, but this method is time-consuming and labor-intensive and has a subjective readout. Here, we describe an innovative neutralization assay based on a modified vaccinia virus Ankara (MVA) vector expressing the green fluorescent protein (MVA-gfp). This MVA-gfp neutralization assay is rapid and sensitive and has a high-throughput potential. Thus, it is suitable to monitor the immune response and eventually the efficacy of a large campaign of vaccination against smallpox and to study the vector-specific immune response in clinical trials that use genetically engineered vaccinia viruses. Most importantly, application of the highly attenuated MVA eliminates the safety concern in using the replication-competent vaccinia virus in the standard clinical laboratory.  相似文献   
8.
BACKGROUND: Rabies is an enzootic and fatal disease and is still a major problem in developing countries. Ante mortem diagnosis in human cases is necessary for medical management of the patient and to ensure appropriate post-exposure treatment of contacts. Both conventional RT-PCR and Real time PCR (TaqMan) have been described for the detection of rabies virus RNA from saliva and tissue respectively, however to date, there have been no studies comparing conventional and real time PCR assays for detection of rabies virus nucleic acid using saliva samples for ante mortem diagnosis. OBJECTIVES: In this study, we evaluated the utility of conventional RT-PCR and SYBR Green I Real time PCR in the ante mortem diagnosis of rabies using saliva samples. STUDY DESIGN: Saliva samples collected from twenty-four patients presenting with typical clinical manifestations of rabies were tested in the two assays. RESULTS: Amongst the 24 samples tested, 21 samples (87.5%) were positive by either of the two molecular methods. Of these 21, rabies virus RNA was detected in 6/21 in the conventional RT-PCR assay while SYBR Green I Real time PCR could detect RNA in 18/21 samples. CONCLUSION: Real time PCR assay was more sensitive than conventional RT-PCR assay (sensitivity 75% versus 37%, p=0.0189). This study highlights the utility of molecular diagnostic tests in establishing ante mortem diagnosis of rabies using saliva samples within a few hours.  相似文献   
9.
10.
Abstract: Analysis and characterization of membrane proteins and hydrophobic peptides by matrix‐assisted laser desorption ionization time‐of‐flight (MALDI‐TOF) mass spectrometry (MS) is a considerable challenge because of their lower ionization efficiency. Detergents are used to solubilize hydrophobic peptides and proteins. However, in MALDI‐MS, the presence of detergents can cause considerable loss of signal intensity. The extent of interference depends on the matrix/sample preparation method and experimental conditions. In the present study, we have analyzed the MALDI response of multiple fatty acylated peptides in the presence of the matrices α‐cyano‐4‐hydroxy cinnamic acid (HCCA) and 2,5‐dihydroxy benzoic acid (DHB). The effect of adding the nonionic detergent n‐octylglucoside (OG) was also examined. The presence of OG facilitated detection of tetrapalmitoylated peptide, particularly when HCCA was used as the matrix. When DHB was used as the matrix, good signal intensity was observed in the absence of OG. Lower laser pulse rate in the linear mode of analysis resulted in good signal intensity for the tetrapalmitoylated peptide. Conditions for obtaining good signal intensities for dipalmitoylated and N‐myristoyl peptides with both HCCA and DHB as matrices were also investigated.  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