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   7198篇
  免费   509篇
  国内免费   229篇
耳鼻咽喉   34篇
儿科学   24篇
妇产科学   55篇
基础医学   576篇
口腔科学   63篇
临床医学   561篇
内科学   451篇
皮肤病学   83篇
神经病学   301篇
特种医学   59篇
外国民族医学   1篇
外科学   241篇
综合类   1864篇
预防医学   360篇
眼科学   49篇
药学   566篇
  19篇
中国医学   2339篇
肿瘤学   290篇
  2024年   15篇
  2023年   41篇
  2022年   133篇
  2021年   157篇
  2020年   219篇
  2019年   98篇
  2018年   101篇
  2017年   181篇
  2016年   286篇
  2015年   271篇
  2014年   551篇
  2013年   463篇
  2012年   535篇
  2011年   633篇
  2010年   543篇
  2009年   442篇
  2008年   365篇
  2007年   376篇
  2006年   336篇
  2005年   284篇
  2004年   278篇
  2003年   264篇
  2002年   181篇
  2001年   178篇
  2000年   180篇
  1999年   148篇
  1998年   87篇
  1997年   109篇
  1996年   63篇
  1995年   62篇
  1994年   69篇
  1993年   57篇
  1992年   61篇
  1991年   37篇
  1990年   42篇
  1989年   23篇
  1988年   19篇
  1987年   12篇
  1986年   6篇
  1985年   13篇
  1984年   9篇
  1983年   6篇
  1980年   1篇
  1977年   1篇
排序方式: 共有7936条查询结果,搜索用时 15 毫秒
51.
The chronological changes in the gene expression for three species of cytosolic fatty acid-binding proteins (FABPs) in the rat brain were examined by Northern and in situ hybridization analyses. The expression for heart(H)-FABP became evident after birth, with a gradual increase and confined to the gray matter, suggesting that the expression of H-FABP mRNA is neuron-specific in postnatal brain. The expression for brain(B)-FABP was very intense in the ventricular germinal zone, without expression in the cerebellar external granule cell layer, suggesting the dominant expression in the cells of glial lineage. B-FABP mRNA was transiently expressed in perinatal gray as well as white matter and the expression in glial cells persists only in the olfactory nerve fiber layer at the adult stage. On the other hand, the expression for skin type(S)-FABP was evident in the both ventricular germinal zone and cerebellar external granule cell layer, suggesting the expression in cells of neuronal lineage. The expression for S-FABP was evident in the prenatal gray matter and S-FABP mRNA was expressed in glial cells at early postnatal stage, whereafter the expression decreased to, but remained at weak levels in the adult brain. Discrete functions of the three FABPs were suggested in neurons and glia differentially at various developmental stages.  相似文献   
52.
目的:在大肠杆菌中表达猪戊型肝炎病毒ORF2区主要结构蛋白,并对其进行血清学鉴定。方法:通过RT-PCR技术从一份猪粪中扩增并克隆戊型肝炎病毒主要的结构基因片段,将该片段插入pET-32a表达载体,在原核系统中融合表达蛋白,Western blot和间接ELISA方法分析该蛋白的抗原性。结果:SDS-PAGE分析结果表明,获得45kD的目的蛋白,该重组蛋白可以与HEV阳性血清反应,而不与阴性血清反应,表明该蛋白具有良好的抗原性。结论:本研究获得了猪戊型肝炎病毒重组抗原,可与HEV阳性血清产生特异性的结合反应,可以作为诊断用的重组蛋白,为研制敏感、特异的HEV诊断试剂盒,行之有效的HEV基因工程疫苗及为HEV感染的预防和临床治疗提供资料。  相似文献   
53.
Analyzing the status of T-cell receptor (TCR) gene rearrangements has been an essential part of deciphering the stages of thymocyte development, understanding the β vs. γδ lineage decision, and characterizing T-cell leukemias. Methods such as PCR and quantitative Southern blotting provide useful information, but also have significant shortcomings such as lack of quantitation in the case of PCR and technical challenges in the case of Southern blotting. Here we describe a real-time PCR method that overcomes many of these shortcomings. This new method shows comparable results for the fraction of unrearranged TCRγ and TCRβ genes in human thymocytes and peripheral blood T cells as Southern blotting, and has the advantages of being simple to perform, highly quantitative, and requiring nanogram quantities of DNA. We also describe a real-time PCR method to quantitate T-cell receptor excision circles formed during TCRβ rearrangements.  相似文献   
54.
The monoclonal antibody technology has provided a means to produce a supply of highly specific uniform antibody which is useful in the detection of plant viruses and which facilitates disease resistance screening. Because of the specificity of a monoclonal antibody to an epitope, a monoclonal antibody may not react to a partially degraded protein. Wheat streak mosaic virus (WSMV) is a member of the potyvirus group and is transmitted by the wheat curl mite Eriophyes tulipae Keifer. The capsid protein of WSMV, like many potyviruses, is degraded in planta. Monoclonal antibodies produced to WSMV reacted to native as well as trypsin treated virions. The antibodies were also useful for evaluation of hard red winter wheat cultivars inoculated with WSMV in the fall or in the spring under field conditions.  相似文献   
55.
Human papillomavirus types in anogenital warts of children   总被引:3,自引:0,他引:3  
Tissue from anogenital warts of 25 children, 10 of whom were suspected of being victims of sexual abuse, was investigated by dot blot and Southern blot techniques for human papillomavirus (HPV) types. HPV DNA was detected in 22 children, two of whom had double infections. The genital HPV types 6 and/or 11 were detected in 20 children, and in three children other HPV types were found. One had HPV 18 (as well as 11); in a second child a possible skin type, HPV 2, was detected; and the third child was infected with an unidentified type. In three cases genital wart material was available from one of the parents, and in all three the HPV type was the same as that of the child. For nine other children one or both parents were reported to have genital warts. The source of infection appeared to be the adult genital tract, but sexual contact might not be the only means of transmission.  相似文献   
56.
目的探讨腰椎管狭窄临床治疗的方法。方法230例腰椎管狭窄病人,采用中两医结合治疗,治疗时间10~30天,平均20天,回顾性分析其治疗效果。结果经1~3年随访(平均20个月),按照中华骨科学会脊柱外科的评定标准优62例(29.8%),良127例(61%),差19例(9.2%),优良率90.8%。结论对于腰椎管狭窄症采用卧床休息,适当运动,合理锻炼,骶管疗法,中药的辨证施治等措施,结果表明,本方法为治疗腰椎管狭窄症的一种好方法。  相似文献   
57.
聚合酶链反应标记轮状病毒地高辛素探针的初步应用   总被引:3,自引:0,他引:3  
目的为探讨聚合酶链反应(PCR)技术标记的地高辛素(DIG)探针的特异性和敏感性。方法用聚合酶链反应技术制备地高辛素标记的人类轮状病毒(HRV)cDNA探针,经cDNA-RNA斑点杂交。结果该探针具HRV特异性,可检出10pg的RNA。应用该项技术检测了120份婴幼儿腹泻粪样标本,其阳性率为65%,明显高于PAGE方法(49.1%)的阳性率。结论PCR方法直接制备地高辛素标记的cDNA探针方便、快速、特异性好、标记率高。  相似文献   
58.
禽流感H9亚型血凝素单克隆抗体的研制和初步应用   总被引:3,自引:0,他引:3  
目的:获得特异针对禽流感H9亚型血凝素单克隆抗体。方法:以H9N2亚型病毒制成疫苗免疫BALB/c小鼠,取脾细胞与SP2/0细胞融合,取细胞上清用HI筛选。结果:共获得9株稳定分泌针对血凝素蛋白抗体的杂交瘤细胞;经广谱性和特异性鉴定,所有单抗株均能与所有检测的82株不同年代不同地方不同禽源H9亚型流感病毒大部分分离株反应,且所有单抗株均不与非AIV-H9病毒反应,而其中一株(8E6)能与所有检测的H9亚型病毒株反应。进行Western blot分析显示,其中8株单抗能与AIV的Mr为75000处反应,表明是针对AIVH9HA的单抗。结论:本试验获得9株广谱性特异性很好的单抗,特别是8E6株;这些单抗株为以后作病毒抗原性位点分析、临床检测和流行病学调查提供了良好试剂。  相似文献   
59.
目的 对上海人群4p35位点D4Z4重复序列进行研究,分析D4Z4的多态性。方法 191名正常上海人的基因组DNA经EooR I/Bln I双酶水解后,应用脉冲场凝胶电泳及Southem印迹测定其染色体4p35位点的D4Z4片段长度,并对短的D4Z4片段Kpn I酶进行部分酶切以计数其D4Z4串联重复序列数。结果 在191名正常上海人群中,有17人(占8.9%)携带短的D4Z4片段,其长度在22-34kb之间;其中16人携带的短D4Z4片段位于4q35位点,1人携带的短D4Z4片段为4q35→10q26。结论 面肩肱型肌营养不良症的发病虽与4q35位点D4Z4片段的串联重复序列数减少有关,但上海人群中携带4q35位点短的D4Z4片段个体的比例明显高于西方人群,提示其他因素可能也参与面肩肱型肌营养不良症的发病。  相似文献   
60.
Aquaporins (AQPs) are water channel proteins that permit osmotically driven water movement. To determine their dynamics in pulmonary oedema, we examined the expression of mRNA and protein for AQP1, AQP3, AQP4, and AQP5 in the lungs of normal and thiourea-treated rats. In the thiourea group, lung water content increased significantly (vs. controls) with the peak at around 4 h. Semi-quantitative RT-PCR showed that AQP3 mRNA in the thiourea group rose significantly, peaking at around 4–8 h. The expression of AQP1, AQP4, AQP5, ENaC and CFTR mRNA each decreased significantly some time after the peak in lung water content. Immunoblot analysis showed that glycosylated AQP3 protein was increased 4–10 h after treatment. Expression of the other AQP proteins was not significantly altered, except for that of AQP4. Immunohistochemical examination revealed that AQP1 was expressed in endothelia, AQP3 in the basal cells of the large airways and in cuboidal cells in the bronchioles, AQP4 in the basolateral membrane of airway cells and AQP5 in type-I pneumocytes. Our results suggest that AQP3 is expressed not only in large airways, but also in bronchioles, and is related to water movement in pulmonary oedema.  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