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   84834篇
  免费   6086篇
  国内免费   3919篇
耳鼻咽喉   349篇
儿科学   1523篇
妇产科学   856篇
基础医学   13328篇
口腔科学   1684篇
临床医学   7165篇
内科学   14357篇
皮肤病学   1047篇
神经病学   7761篇
特种医学   1391篇
外国民族医学   15篇
外科学   4953篇
综合类   14933篇
现状与发展   22篇
预防医学   4904篇
眼科学   966篇
药学   11188篇
  15篇
中国医学   3055篇
肿瘤学   5327篇
  2024年   101篇
  2023年   851篇
  2022年   1589篇
  2021年   3031篇
  2020年   2458篇
  2019年   2108篇
  2018年   2076篇
  2017年   2431篇
  2016年   2751篇
  2015年   3117篇
  2014年   5271篇
  2013年   5885篇
  2012年   5641篇
  2011年   6266篇
  2010年   4973篇
  2009年   4786篇
  2008年   4945篇
  2007年   4817篇
  2006年   4322篇
  2005年   4049篇
  2004年   3311篇
  2003年   2817篇
  2002年   2178篇
  2001年   1873篇
  2000年   1591篇
  1999年   1381篇
  1998年   1268篇
  1997年   1106篇
  1996年   957篇
  1995年   768篇
  1994年   732篇
  1993年   615篇
  1992年   526篇
  1991年   496篇
  1990年   416篇
  1989年   334篇
  1988年   321篇
  1987年   310篇
  1986年   274篇
  1985年   384篇
  1984年   334篇
  1983年   217篇
  1982年   265篇
  1981年   210篇
  1980年   177篇
  1979年   115篇
  1978年   94篇
  1977年   78篇
  1976年   68篇
  1975年   53篇
排序方式: 共有10000条查询结果,搜索用时 406 毫秒
101.
胃癌组织p16基因蛋白表达的意义   总被引:9,自引:4,他引:5  
目的 检测 p1 6基因蛋白在胃癌组织、癌旁组织中的表达及其分布特点 ,分析其与胃癌临床病理学特征及预后的关系 .方法 采用 S- P免疫组织化学法对 53例胃癌组织及 35例癌旁组织进行 p1 6蛋白的定位观察 .结果 各病理类型胃癌组织、癌旁组织均有 p1 6基因蛋白表达 .阳性率分别为 62 .3% (33/53)和 88.6% (31 /35) ,阳性细胞的棕黄色颗粒主要位于细胞核 .胃癌 p1 6基因蛋白表达与性别、年龄、肿瘤部位在统计学上无差异 (P>0 .0 5) ;而与组织学类型、病理分级、淋巴结转移、临床病理分期在统计学上有差异 (P<0 .0 5) .p1 6蛋白阳性者 5年生存率 51 .0 %高于 p1 6蛋白阴性者 2 0 .0 % (P<0 .0 5) .结论  p1 6基因缺失和表达水平的改变与胃癌发生、发展密切相关 ,检测 p1 6基因蛋白表达可作为辅助临床判断胃癌的生物学行为及推测预后的指标  相似文献   
102.
目的研究P16、Cyclin、D1Rb基因在胃癌中的表达及其与胃癌生物学行为的关系.方法采用免疫组化方法检测10例正常胃黏膜、30例胃癌组织中P16、Cyclin D1、Rb蛋白的表达,并结合其临床资料进行分析.结果P16、Cyclin D1、Rb蛋白阳性表达,正常胃粘膜分别为90%、10%、90%;胃癌分别为36.67%、53.33%、50%,胃癌纽与正常对照组间差异均有显著性(P<0.05),P16、Cyclin D1蛋白与胃癌分化程度、淋巴结转移与否、远处转移与否呈一定的相关性.结论P16、Cyclin D1、Rb基因与胃癌发生有关,P16、Cyclinp蛋白检测有助于胃癌预后的判断.  相似文献   
103.
C-反应蛋白水平对急性缺血性脑卒中预后影响的系统评价   总被引:1,自引:0,他引:1  
目的 应用Meta分析,评价C-反应蛋白(C-reactive protein,CRP)水平对急性缺血性脑卒中预后的影响.方法 计算机检索PubMed、MEDLINE(1991-2006)、中国学术期刊全文数据库(1979-2006)等.搜集CRP水平对急性缺血性脑卒中预后影响非随机对照研究,逐篇评价纳入文献的质量,采用RevMan4.2版软件进行Meta分析.结果 共纳入7篇文献(外文4篇,中文3篇),涉及841例患者.在急性缺血性脑卒中患者中,3个月以上随访截尾时间的死亡率和再发血管事件与CRP水平相关,CRP增高组发生率比CRP正常组分别高2.71和1.81倍[OR合并分别为3.71和2.81,95%CI分别为(2.40,5.73)和(1.42,5.53)]均有统计学意义(P<0.05);CRP测量值与缺血性脑卒中复发和死亡亦相关,在复发患者中,CRP测量值平均高于未复发者为3.52 mg/L[WMD=3.52,95%CI(-0.01,7.05)],具有一定的临床意义;在死亡患者中,CRP测量值平均高于生存者为8.02 mg/L[WMD=8.02,95%CI(5.68,10.37)],具有统计学意义(P<0.05).结论 发病时CRP的水平可以初步评价急性缺血性脑卒中患者的预后.  相似文献   
104.
目的观察银杏叶提取物与脑蛋白联用治疗脑梗塞的疗效及对血液流变学指标的影响。方法132例脑梗塞患者随机分为治疗组及对照组。治疗组给舒血宁20 mL,脑蛋白注射液60 mg,1次/d静滴,连用14 d观察治疗前后疗效及血流变指标变化。结果与对照组比较治疗前后疗效及血流变指标均有显著改善。结论银杏叶提取物(舒血宁)合用脑蛋白注射液治疗脑梗塞,可降低血粘度,促进神经功能改善。  相似文献   
105.
The aim of this research was to assess whether common genetic variants within the C-reactive protein gene ( CRP ) are related to the degree of acute rise in plasma C-reactive protein (CRP) levels following an acute coronary syndrome (ACS). While polymorphisms within CRP are associated with basal CRP levels in healthy men and women, less is known about the relationship of such genetic variants and the degree of CRP rise during and after acute ischemia. Plasma CRP is associated with increased rates of recurrent coronary events. We evaluated seven common genetic variants within CRP and assessed their relationship to the degree of rise in CRP levels immediately following an acute coronary syndrome in 1827 European American patients. Variants in the putative promoter region, −757T > C and −286C > T > A, were associated with the highest CRP elevations after ACS. Patients with two copies of the A allele of SNP −286C > T > A had median CRP values of 76.6 mg/L, compared to 11.1 mg/L in patients with no copies of the rare variant (p-value <0.0001), post ACS. The lowest CRP values were found for patients with minor alleles of the exonic 1059G > C and the 3'untranslated region 1846G > A SNPs. For example, patients homozygous for the minor allele of 1059G > C had 71% lower median CRP values than those homozygous for the major allele [3.5 vs 12.0 mg/L, p < 0.0001]. These trends persisted in the chronic stable phase after ischemia had resolved, and after adjustment for infarct size by peak creatinine kinase levels and clinical status by Killip class. Assessment of CRP genetic variants identified patients with higher and lower CRP elevation after acute coronary syndrome.  相似文献   
106.
107.
Immunohistochemical and immunoelectron microscopical studies were carried out on 28 aged dogs' brains. Amyloid deposits were seen in the arteries and capillaries in the leptomeninges and in superficial areas of the cortices in 19 (67.9%) of the 28 dogs (10-22 years of age). Immunohistochemically, these amyloid deposits were reactive for anti-beta/A4 antibody. Additionally, a variable number of parenchymal deposits with diffuse beta/A4-immunoreactivity (diffuse plaques) was also noted throughout the cerebral cortex in 24/28 dogs (85.7%). However, these plaque lesions were undetectable in Congo red staining. Electron microscopically, amyloid fibrils, measuring 10 nm in width, were located mainly in the tunica media of the arteries, and in less involved vessels they tended to be present among collagen fibres in the adventitia and smooth muscle cells in the outer layer of the media. The plaque lesions appeared to contain sparse aggregations of amyloid fibrils. In immunoelectron microscopical examinations, all amyloid fibrils in both blood vessels and plaques were selectively labelled by gold particles. These findings indicate that aged dogs can provide a useful experimental model for research into the beta/A4-type of cerebral amyloidosis commonly seen in Alzheimer's disease.  相似文献   
108.
109.
以钒基核苷酸复合物为核酸酶抑制剂,从人胚组织中制备总RNA,所得产品几乎不含DNA和蛋白质,经过分离Poly(A)~ mRNA,证明制品有合成cDNA的完整功能,方法比较简捷,适于大量制备以满足分离mRNA 之需,并讨论了此法的优缺点。  相似文献   
110.
The advent of recombinant DNA technology has led to the identification in the DNA of normal animal cells of over 30 proto-oncogenes that are homologous to retroviral transforming genes. One of these encodes a protein kinase (pp60c-src) of unknown function, that is preferentially synthesized in brain and neural retina. Here the expression of pp60c-src in the peripheral nervous system was examined in sensory neurons from chick dorsal root ganglia with antisera raised against the transforming protein of Rous sarcoma virus (pp60v-src) expressed in Escherichia coli carrying the cloned v-src gene. This antiserum recognizes pp60c-src specifically in normal chicken cells. Western immunoblotting showed that dorsal root ganglia of stage 30 (day 6.5) chick embryos contained elevated levels of pp60c-src. Immunoperoxidase staining of neuron-enriched cultures prepared from chick dorsal root ganglia showed pp60c-src immunoreactivity in cells with neuronal morphology; flat, fibroblastic cells contained no detectable immunoreactivity. Indirect double immunofluorescence with pp60src antibodies and monoclonal antibodies against the 200-kD subunit of neurofilament protein confirmed that the cells expressing pp60c-src were neurons. Ninety-six percent of the neurofilament-positive cells were immunoreactive with pp60src antibodies, and conversely, all pp60c-src-positive cells were immunoreactive with neurofilament antibodies. pp60c-src immunofluorescence appeared to be distributed over the cell body, processes, and growth cones. These results clearly demonstrate that pp60c-src is a product of neurons and is expressed in sensory neurons in culture.  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