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   463篇
  免费   23篇
  2023年   1篇
  2022年   6篇
  2021年   3篇
  2020年   4篇
  2019年   3篇
  2018年   8篇
  2017年   8篇
  2016年   11篇
  2015年   16篇
  2014年   15篇
  2013年   39篇
  2012年   34篇
  2011年   24篇
  2010年   11篇
  2009年   17篇
  2008年   26篇
  2007年   38篇
  2006年   25篇
  2005年   32篇
  2004年   28篇
  2003年   23篇
  2002年   22篇
  2001年   8篇
  2000年   12篇
  1999年   6篇
  1998年   9篇
  1997年   3篇
  1996年   3篇
  1995年   4篇
  1994年   3篇
  1993年   3篇
  1992年   7篇
  1991年   4篇
  1990年   4篇
  1989年   3篇
  1988年   5篇
  1987年   1篇
  1986年   1篇
  1985年   1篇
  1984年   2篇
  1983年   1篇
  1982年   3篇
  1980年   1篇
  1979年   2篇
  1977年   1篇
  1975年   1篇
  1974年   1篇
  1972年   1篇
  1967年   1篇
  1960年   1篇
排序方式: 共有486条查询结果,搜索用时 15 毫秒
161.
162.
163.
164.
Objective: The present study compared surface electromyographic (sEMG) activity obtained from the submental muscle group for a tongue press and a head lift exercise as potential therapeutic exercises for dysphagic elderly. Materials and methods: Fifty‐three healthy volunteers with a mean age of 35.3 participated in this study. Subjects were required to perform an isometric task, pressing their tongue against the hard palate, and an isotonic task requiring sustained lingual force against the hard palate. Pressure sensors were used to measure the amount of lingual pressure against the hard palate. Submental sEMG data from these tasks were compared with those obtained from the isometric and isotonic aspects of a head lift exercise. Results: No sEMG differences were identified between the isometric tongue press task and head lift exercise. Isotonic tongue press exercises resulted in significantly higher maximum and mean sEMG values compared with the isotonic head lift exercise (p < 0.05). The submental sEMG activity from the tongue press exercise was equal (isometric) to, or greater (isotonic) than comparable muscle activation obtained during the head lift exercise. Conclusions: The tongue press exercise may be less strenuous than the head lift exercise while achieving the same therapeutic effect.  相似文献   
165.
166.
A 24-alkylsterol, crinosterol [(24S)-24-methylcholesta-5,22(E)-dien-3beta-ol] has been isolated from sea-dwelling animals, protists and plants. Here, we identified crinosterol from nine species of mites (Acari). The compound was identified by using (1)H-NMR analysis and GCMS spectral data along with the HPLC retention time by comparing with those of the synthesized compound. As far as we know, this is the first report on the identification of crinosterol from arthropods. Furthermore, after Rhizoglyphus robini were fed on artificial diets with d(3)-methionine, d(2)-crinosterol was detected from the mite's extracts. The incorporation of two deuterium atoms into the sterol indicated that a d(3)-methyl group was introduced into the C24 of the side chain to form crinosterol. Although the details of the biosynthesis of crinosterol remain unknown, the discovery of crinosterol in the mites implies the existence of interesting sterol metabolisms in the animals.  相似文献   
167.
The term "supernumerary teeth" describes production of more than the normal number of teeth in the primary or permanent dentitions. Their aetiology is not understood. Uterine sensitization associated gene-1 (USAG-1) is a BMP antagonist that plays important roles in the local regulation of BMP signaling by binding and neutralizing BMP activities, and also serves as a modulator of Wnt signaling. We report here that USAG-1 deficient mice have supernumerary teeth. The supernumerary maxillary incisor appears to form as a result of the successive development of the rudimentary upper incisor tooth. We confirmed that the USAG-1 expression is localized to the epithelium and mesenchyme of the rudimentary maxillary incisor tooth organ formation. USAG-1 abrogation rescued apoptotic elimination of odontogenic mesenchymal cells. Based upon these results, we conclude that USAG-1 controls the number of teeth in the maxillary incisor region by regulating apoptosis.  相似文献   
168.
Molecular Biology Reports - Although skin manifestations are common in diabetic patients, its characteristics are poorly identified. This study explored the differentiation process of keratinocytes...  相似文献   
169.
In the United States, biliary atresia (BA) is the most frequent indication for liver transplantation in pediatric patients. BA is a complex disease, with suspected environmental and genetic risk factors. A genome-wide association study in Chinese patients identified association to the 10q24.2 (hg18) genomic region. This signal was upstream of two genes, XPNPEP1 and ADD3, both expressed in intrahepatic bile ducts. We tested association to this region in 171 BA patients and 1,630 controls of European descent and found the strongest signal to be at rs7099604 (p = 2.5 × 10?3) in intron 1 of the ADD3 gene. Moreover, expression data suggest that ADD3, but not XPNPEP1, is differentially expressed in BA patients. The role of ADD3 in biliary development is unclear, but our findings suggest that this gene may be functionally relevant for the development of BA.  相似文献   
170.
The N 1-methyladenosine residue at position 58 of tRNA is found in the three domains of life, and contributes to the stability of the three-dimensional L-shaped tRNA structure. In thermophilic bacteria, this modification is important for thermal adaptation, and is catalyzed by the tRNA m1A58 methyltransferase TrmI, using S-adenosyl-l-methionine (AdoMet) as the methyl donor. We present the 2.2 Å crystal structure of TrmI from the extremely thermophilic bacterium Aquifex aeolicus, in complex with AdoMet. There are four molecules per asymmetric unit, and they form a tetramer. Based on a comparison of the AdoMet binding mode of A. aeolicus TrmI to those of the Thermus thermophilus and Pyrococcus abyssi TrmIs, we discuss their similarities and differences. Although the binding modes to the N6 amino group of the adenine moiety of AdoMet are similar, using the side chains of acidic residues as well as hydrogen bonds, the positions of the amino acid residues involved in binding are diverse among the TrmIs from A. aeolicus, T. thermophilus, and P. abyssi.  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