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   1940篇
  免费   113篇
  国内免费   40篇
耳鼻咽喉   7篇
儿科学   71篇
妇产科学   21篇
基础医学   161篇
口腔科学   33篇
临床医学   281篇
内科学   549篇
皮肤病学   25篇
神经病学   113篇
特种医学   155篇
外科学   153篇
综合类   167篇
一般理论   3篇
预防医学   182篇
眼科学   11篇
药学   80篇
中国医学   14篇
肿瘤学   67篇
  2023年   14篇
  2022年   8篇
  2021年   17篇
  2020年   17篇
  2019年   14篇
  2018年   36篇
  2017年   22篇
  2016年   24篇
  2015年   16篇
  2014年   26篇
  2013年   47篇
  2012年   110篇
  2011年   115篇
  2010年   70篇
  2009年   55篇
  2008年   94篇
  2007年   119篇
  2006年   93篇
  2005年   106篇
  2004年   155篇
  2003年   115篇
  2002年   106篇
  2001年   71篇
  2000年   43篇
  1999年   64篇
  1998年   89篇
  1997年   75篇
  1996年   53篇
  1995年   35篇
  1994年   33篇
  1993年   45篇
  1992年   30篇
  1991年   17篇
  1990年   25篇
  1989年   18篇
  1988年   19篇
  1987年   20篇
  1986年   12篇
  1985年   9篇
  1983年   4篇
  1982年   4篇
  1980年   4篇
  1979年   3篇
  1977年   6篇
  1976年   3篇
  1975年   4篇
  1974年   5篇
  1973年   4篇
  1972年   3篇
  1969年   3篇
排序方式: 共有2093条查询结果,搜索用时 171 毫秒
1.
2.
作者报告经病理诊断消化道恶性肿瘤患者30例及手术切除肿瘤患者15例的血浆胃动素水平,并以健康成人31例作为对照。消化道恶性肿瘤的胃动素水平373.4±123.7ng/L,显著高于正常对照组(162.3±52.3ng/L,P<0.001),而消化道恶性肿瘤患者术前及术后胃动素水平无显著差异。消化道恶性肿瘤患者胃动素水平增高的原因可能是肿瘤刺激神经所致。胃癌和结肠癌细胞可产生胃泌素样物质,它可刺激胃动素的释放。  相似文献   
3.
4.
报告手术治疗腰椎间盘突出症合并退行性腰椎管狭窄症104例。术后随访90例,随诊时6个月~6年。优良率86.5%,无腰椎不稳和腰椎滑脱等并发症。为获得优良效果,作者强调在处理椎间盘突出的同时必须彻底解除侧隐窝及神经根管,黄韧带肥厚对神经根的压迫,才能彻底根除症状  相似文献   
5.
报道了氯仿重结晶的棉酚的化学性质,样品在不同温度下干燥恒重后,经熔点、薄层层析、紫外光谱、红外光谱、X-射线衍射、热重量分析、元素(C,H,Cl)分析及棉酚合量测定等一系列的分析,确证了在60℃以下棉酚与氯仿成溶剂化物(solvate)。随着干燥温度的升高或在室温长时间的贮存,此现象逐渐消失,100℃真空干燥恒重后成为纯棉酚。  相似文献   
6.
SUMMARY. There are no current U.K. or international guidelines or regulations covering the production, processing and storage of haemopoietic cells such as to allow their engraftment following myeloablative therapy. This paper seeks to provide such guidelines. It enumerates how quality control and assurance can be applied to this area of transfusion medicine; procedural steps relating to bone marrow harvest on peripheral blood stem cell collection are outlined and recommended doses of nucleated cells suggested for both procedures. General specifications for identification, storage and transportation of bone marrow and peripheral blood stem cells are included and specific laboratory procedures related to the provision of haemopoietic cells for engraftment are outlined. Umbilical cord blood transplants and long-term bone marrow culture are alluded to but these are still in a research phase.  相似文献   
7.
8.
Gramzinski  RA; Broze  GJ Jr; Carson  SD 《Blood》1989,73(4):983-989
Studies of proteins that inhibit tissue factor activity have generally been conducted using either an extracted tissue homogenate ("thromboplastin") or tissue factor protein reconstituted into phospholipid vesicles rather than with tissue factor expressed in cell membranes (its physiological environment). In the present study, a human fibroblast cell strain was used to evaluate the effects of lipoprotein associated coagulation inhibitor (LACI), placental anticoagulant protein (PAP), and apolipoprotein A-II (apo A-II) on human tissue factor in cell membranes. LACI was tested from 7.8 to 500 pmol/L on fibroblasts cultured at cell densities ranging from 3,500 to 9,925 cells/well, and caused a progressive inhibition of tissue factor activity. PAP was tested from 3.9 nmol/L to 1 mumol/L at cell densities ranging from 4,500 to 15,400 cells/well and caused up to 83% inhibition of tissue factor activity. Inhibition by these proteins appeared to be influenced by cell density as well as whether the cells were intact or disrupted. Apo A-II, up to 1 mumol/L, did not inhibit the tissue factor activity of intact or disrupted fibroblasts at any cell density examined even though it did inhibit the activity of tissue factor in phospholipid vesicles. Of these inhibitors of tissue factor-dependent activation of factor X, LACI was the most effective in suppressing the generation of factor Xa activity. The effects obtained with apo A-II are clearly dependent on the nature of the tissue factor preparation with which it is tested. The disparity between the inhibitory effect of apo A-II on the activity of tissue factor reconstituted into lipid vesicles and the absence of effect on the activity of tissue factor remaining in cell membranes serves to reemphasize the necessity of reexamining results obtained with model systems using as nearly physiological reagents as possible.  相似文献   
9.
肺神经内分泌癌的免疫组化与免疫电镜研究   总被引:3,自引:1,他引:3  
本文应用免疫组化与免疫电镜技术对20例肺神经内分泌癌进行了研究,另6例非神经内分泌癌作为对照。结果表明:嗜铬颗粒蛋白A免疫组化染色19/20例阳性,免疫电镜能够比较特异地标记神经分泌颗粒,具有确诊意义;神经特异性烯醇化酶染色20/20例阳性,非神经内分泌癌3/6例阳性,免疫电镜下无特异性分布,适宜作为诊断的筛选指标;S-100蛋白和5-HT亦可作为诊断之参考。  相似文献   
10.
Usher syndrome is recognized as the most frequent cause of hereditary deaf-blindness. Usher syndrome type I (USH1), the most severe form of the disease, is characterized by profound congenital sensorineural deafness, constant vestibular dysfunction, and retinitis pigmentosa of prepubertal onset. This form is genetically heterogeneous and five loci (USH1A-E) have been mapped thusfar. However, only the gene responsible for USH1 B (which accounts for approximately 75% of USH1 cases) has been characterized. It encodes a long-tailed unconventional myosin, myosin VIIA, with a predicted 2215 amino acid sequence. Primers covering the complete myosin VIIA coding sequence as well as the 3' non coding sequence were designed, allowing direct sequence analysis of each of the 48 coding exons and flanking splice sites in seven patients affected by USH1. Four novel mutations were thereby identified. The possibility should now be considered of a sequence-based prenatal diagnosis in some of the families affected by this very severe form of Usher syndrome.   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