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   187篇
  免费   4篇
  国内免费   75篇
  2019年   1篇
  2018年   1篇
  2016年   2篇
  2013年   1篇
  2012年   10篇
  2011年   14篇
  2010年   4篇
  2009年   4篇
  2008年   5篇
  2007年   6篇
  2006年   9篇
  2005年   47篇
  2004年   49篇
  2003年   3篇
  2002年   8篇
  2001年   15篇
  2000年   57篇
  1999年   15篇
  1998年   6篇
  1997年   3篇
  1996年   1篇
  1995年   1篇
  1991年   1篇
  1987年   1篇
  1985年   1篇
  1984年   1篇
排序方式: 共有266条查询结果,搜索用时 312 毫秒
51.
Copyright by Science in China Press 2005 Primary hepatocarcinoma is one of the most fre-quent digestive-tract cancers, particularly in China. The incidence and death rate of primary hepatocarci-noma in China is the highest in the world, with about 1100 thousands people dying from primary hepatocar-cinoma per year[1]. Although the chemotherapeutic agents are the main therapeutic approach for hepato- carcinoma, they are relatively ineffective and result in many toxic and side effects. Accordin…  相似文献   
52.
Myostatin (GDF-8, MSTN) is a member of trans- forming growth factors (TGF-β) superfamily, which was first described by McPherron et al. in 1997[1]. Myostatin appears to act as a negative regulator of muscle development and controls not only fibre size but also fibre number[2,3]. Mutations in the third exon of the myostatin gene have been shown to cause dou- ble muscling in cattle[4]. By knocking out the gene of myostatin in mice, they were able to show that the transgenic mice developed …  相似文献   
53.
华烨  梁汝庆  丁新生 《生物磁学》2009,(15):2850-2853
目的:探讨同型半胱氨酸(Hcy)与不同类型脑卒中的关系,并对高Hcy血症成因作初步分析。方法:测定225例缺血性脑卒中和40例出血性脑卒中患者以及85例同龄健康受试者的血浆Hcy水平以及叶酸、维生素B12的浓度,将缺血性卒中按照TOAST分型分为不同临床亚组--动脉粥样硬化性脑血栓形成组,腔隙性脑梗死组,心源性脑栓塞组以及其他或不明原因脑梗死组,并分别与健康组进行对照研究。结果:血浆同型半胱氨酸平均水平在动脉粥样硬化性脑梗死组患者为(16.19±4.35)μmol/L,腔隙性脑梗死患者为(16.89±6.41)μmol/L,心源性脑栓塞组为(18.23±4.83)μmol/L,其他或不明原因脑梗死患者为(17.31±2.56)μmol/L,脑出血组患者为(14.91±4.54)μmol/L,均高于对照组(7.20±7.91)μmol/L,P〈0.05;各缺血性卒中组间同型半胱氨酸水平差异无显著性(P〈0.05);缺血性卒中组患者血浆同型半胱氨酸水平高于出血性卒中组(P〈0.05)。卒中各组叶酸和维生素B12浓度均显著低于对照组(P〈0.05)。结论:血浆同型半胱氨酸在不同类型卒中中均升高,高血浆Hcy水平可能是脑卒中的独立危险因素,叶酸和VitB12缺乏可能是导致高Hcy血症的重要原因。  相似文献   
54.
55.
China is one of the countries in the world with therichest species biodiversityinfreshwater ecosystem.How-ever,duetothe rapid economic growthandthe continuingincrease of human disturbances and destructions of aquatichabitats,the biodiversity of freshwater ecosystemsis dras-tically declining.Waterbodies become more and more“deserted”of sensitive species.Water areas are reduced,fragmentized,and changed in their hydrodynamics(i.e.damming),causing changes in sedimentation and otherchanges.Forinstance,the area o...  相似文献   
56.
Little is known about the genetics of nonsyndromic intellectual disability (NSID). We hypothesized that de novo mutations (DNMs) in synaptic genes explain an important fraction of sporadic NSID cases. In order to investigate this possibility, we sequenced 197 genes encoding glutamate receptors and a large subset of their known interacting proteins in 95 sporadic cases of NSID. We found 11 DNMs, including ten potentially deleterious mutations (three nonsense, two splicing, one frameshift, four missense) and one neutral mutation (silent) in eight different genes. Calculation of point-substitution DNM rates per functional and neutral site showed significant excess of functional DNMs compared to neutral ones. De novo truncating and/or splicing mutations in SYNGAP1, STXBP1, and SHANK3 were found in six patients and are likely to be pathogenic. De novo missense mutations were found in KIF1A, GRIN1, CACNG2, and EPB41L1. Functional studies showed that all these missense mutations affect protein function in cell culture systems, suggesting that they may be pathogenic. Sequencing these four genes in 50 additional sporadic cases of NSID identified a second DNM in GRIN1 (c.1679_1681dup/p.Ser560dup). This mutation also affects protein function, consistent with structural predictions. None of these mutations or any other DNMs were identified in these genes in 285 healthy controls. This study highlights the importance of the glutamate receptor complexes in NSID and further supports the role of DNMs in this disorder.  相似文献   
57.
58.
白介素-10(IL-10)是一种具有重要免疫调节功能的多效性细胞因子,它能影响免疫系统中多种类型细胞的活性。新近,美英科学家克隆了一种独特的人mRNA,它编码名为白介素19(Interleukin-19,IL-19)的新型IL-10同源物。IL-19基因邻近IL-10基因,都位于1号染色体上。IL-19基因由5个外显子和4个内含子组成,由二种不同的启动子转录。IL-19与IL-10有21%aa同源。IL-19mRNA是在活化的巨噬细胞中发现的,其表达相似而又不同于IL-10。IL-19与IL-10的序列比较表明两者不可能共享一种受体。IL-19的鉴定增加了已鉴定的IL-10同源物数并证明了IL-10相关蛋白家族的存在。在活化的巨噬细胞中,IL-19的表达模式不同于IL-10,并且可能通过不同于典型的IL-10受体复合物的不同受体进行信号转导。 [黄仕和译自Gallgaher G et al.Immunol Letters,2000,73(2,3):206]  相似文献   
59.
60.
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