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   3737篇
  免费   159篇
  国内免费   40篇
耳鼻咽喉   12篇
儿科学   86篇
妇产科学   103篇
基础医学   392篇
口腔科学   50篇
临床医学   699篇
内科学   559篇
皮肤病学   55篇
神经病学   293篇
特种医学   237篇
外科学   442篇
综合类   37篇
预防医学   148篇
眼科学   382篇
药学   217篇
肿瘤学   224篇
  2023年   14篇
  2022年   19篇
  2021年   24篇
  2020年   20篇
  2019年   24篇
  2018年   47篇
  2017年   33篇
  2016年   50篇
  2015年   96篇
  2014年   83篇
  2013年   125篇
  2012年   126篇
  2011年   143篇
  2010年   118篇
  2009年   117篇
  2008年   147篇
  2007年   137篇
  2006年   125篇
  2005年   134篇
  2004年   131篇
  2003年   145篇
  2002年   128篇
  2001年   150篇
  2000年   107篇
  1999年   134篇
  1998年   132篇
  1997年   112篇
  1996年   106篇
  1995年   79篇
  1994年   77篇
  1993年   79篇
  1992年   68篇
  1991年   60篇
  1990年   74篇
  1989年   70篇
  1988年   66篇
  1987年   57篇
  1986年   43篇
  1985年   51篇
  1984年   40篇
  1983年   26篇
  1982年   21篇
  1981年   22篇
  1980年   16篇
  1979年   24篇
  1978年   13篇
  1977年   26篇
  1976年   15篇
  1974年   20篇
  1927年   15篇
排序方式: 共有3936条查询结果,搜索用时 171 毫秒
1.
2.
A full-length 2.4-kb cDNA for the FAD-linked glycerol-3-phosphate dehydrogenase (EC 1.1.99.5) was cloned from rat liver using PCR techniques. The cloned gene encodes a protein of 727 amino acids. The calculated molecular mass of 80,898 Da is higher than the apparent molecular mass observed by SDS/PAGE (74,000 Da) of the purified enzyme. This result indicates that the enzyme is synthesized as a precursor with a putative mitochondrial signal sequence. mRNA for this gene was detected in liver, heart, muscle, brain, testes, and pancreas. With the exception of testes, basal expression levels were very low in all tissues examined. However, application of thyroid hormones led to a 10- to 15-fold increase in liver glycerol-3-phosphate dehydrogenase mRNA, whereas hypothyroidism further decreased the mRNA level.  相似文献   
3.
4.
A novel assay for factor XIII is described that utilizes exclusively small synthetic peptides as substrates for the cross-linking reaction catalyzed by activated factor XIII (FXIIIa). The acyl donor substrate (selection peptide) is immobilized on a microplate via biotin while the acyl acceptor substrate (detection peptide) is labeled with the fluorochrome Oregon green to allow sensitive detection without the need for secondary enzyme systems for signal amplification. Starting with an amino acid sequence from the fibrin gamma-chain (GQQHHLGGAKQAGDV) as a prototype peptide, the influence of amino acid exchanges were investigated with respect to their impact on the FXIIIa-catalyzed reaction. It was found that FXIIIa readily accepts a broad range of substrate peptides, with a proline neighboring the essential lysine having the most detrimental effect. The assay appears to be valuable for the molecular characterization of factor XIII and may be used for a deeper investigation into the substrate requirements of this final enzyme of wound repair, and eventually also for the characterization of other transglutaminases.  相似文献   
5.
In an outpatient rehabilitation setting, both patients’ use and therapists’ knowledge of complementary and alternative medicine (CAM) varies widely. Based on this observation and a recognition of CAM as an emerging practice area for rehabilitation professionals, it was felt that a thorough and consistent approach to the education and orientation of physical therapists to the world of CAM and integrative care was needed. This special interest paper will describe one center’s approach, development, and use of a unique and comprehensive training manual designed to provide both a structured and standardized approach for educating physical therapists about CAM and related therapeutic modalities. This innovative teaching tool allows for multiple methods of content delivery within a multidisciplinary format and can be used for those who practice currently or desire to practice in an integrative care environment.  相似文献   
6.
Rasmussen and Milner [N.Y. Acad. Sci. Vol. 299, pp. 355–379, 1977] published data on late-lesioned (after age 6) epileptic patients who had suffered left hemisphere lesions. They estimated that left hemisphere dominance occurred in 96% of dextrals and 70% of sinistrals. These figures have been regarded as valid estimates for normal dextrals and sinistrals. We administered the Bilateral Object Naming Latency Task, a verbal tachistoscopic task with very good psychometric properties, to 188 dextral and 72 sinistral normals. Results showed that 93.6% of the dextrals and 80.3% of the sinistrals were left hemisphere dominant. A consideration of results from a number of carefully conducted dichotic listening studies suggests, as do present results, that the 70% left-dominance estimate of Rasmussen and Milner for normal sinistrals may be too low by about 10%. It is suggested that ‘bilateral dominance’, present in 15% of the epileptic sinistrals of Rasmussen and Milner, may be much less common in normal sinistrals.  相似文献   
7.
A number of novel pyridazinomorphinans have been synthesized by the inverse electron demand Diels-Alder reaction of various 3,6-disubstituted 1,2,4,5-tetrazines with enamines derived from dihydrocodeinone and with codeinone. Reduction of some of the pyridazinomorphinans did not furnish the expected pyrroloepoxymorphinans; in all cases investigated reductive cleavage of the epoxybridge was observed to yield dihydropyridazino- or pyrrolomorphinans. The structures of all new compounds were assigned by the spectral data, that of the cycloadduct of codeinone was additionally verified by X-ray crystallography. Compounds 5a, 8, 11a , and 16 have been evaluated for their affinity at μ and κ opioid receptors in radioligand binding assays. Their ability to inhibit [3H]DAMGO binding at μ and [3H]U 69.593 binding at κ receptors, respectively as compared to codeine has been found to be lower.  相似文献   
8.
The computerized individually adjustable brain atlas (CBA) has been further developed. The atlas was primarily designed for anatomical localization and quantitative evaluation of data in positron emission tomography (PET), but may also be employed for other neuroimaging modalities, such as transmission computed tomography (CT) and magnetic resonance imaging (MRI). The atlas is based on anatomical information obtained from digitized cryosectioned brains. Using spatially standardized and then averaged MRI images, we demonstrate the high localization accuracy and precision of the brain atlas. This is a prerequisite for obtaining accuracy when using the atlas in the localization and the quantitative evaluation of PET data. The specification and the selection of region of interests (ROIs) by the CBA are presented and discussed.  相似文献   
9.
Both cefotiam and ceftizoxime stimulate the uptake of gonococci by polymorphonuclear granulocytes in vitro as can be seen by light microscopy. Although this already holds true of antibiotic concentrations lower than the minimum inhibitory concentration (MIC: 1/4 x) this effect is much more marked at concentrations highly exceeding the MIC (4000 x). As light microscopic investigation allows the analysis of large numbers of cells but no final judgement on actual bacterial engulfment definite phagocytosis is demonstrated by electron microscopy.  相似文献   
10.
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