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   4786篇
  免费   149篇
  国内免费   84篇
耳鼻咽喉   10篇
儿科学   198篇
妇产科学   36篇
基础医学   389篇
口腔科学   112篇
临床医学   418篇
内科学   710篇
皮肤病学   76篇
神经病学   271篇
特种医学   79篇
外国民族医学   2篇
外科学   435篇
综合类   523篇
预防医学   350篇
眼科学   33篇
药学   925篇
中国医学   279篇
肿瘤学   173篇
  2023年   59篇
  2022年   163篇
  2021年   159篇
  2020年   105篇
  2019年   272篇
  2018年   244篇
  2017年   160篇
  2016年   86篇
  2015年   75篇
  2014年   218篇
  2013年   315篇
  2012年   234篇
  2011年   309篇
  2010年   223篇
  2009年   216篇
  2008年   235篇
  2007年   268篇
  2006年   155篇
  2005年   165篇
  2004年   121篇
  2003年   105篇
  2002年   86篇
  2001年   71篇
  2000年   66篇
  1999年   80篇
  1998年   46篇
  1997年   39篇
  1996年   40篇
  1995年   51篇
  1994年   41篇
  1993年   42篇
  1992年   28篇
  1991年   21篇
  1990年   23篇
  1989年   22篇
  1988年   15篇
  1987年   15篇
  1986年   23篇
  1985年   54篇
  1984年   66篇
  1983年   32篇
  1982年   52篇
  1981年   44篇
  1980年   40篇
  1979年   29篇
  1978年   27篇
  1977年   18篇
  1976年   18篇
  1975年   13篇
  1974年   13篇
排序方式: 共有5019条查询结果,搜索用时 15 毫秒
11.
吡哌酸锌对小鼠烫伤感染的体表保护作用   总被引:2,自引:2,他引:0  
目的观察吡哌酸锌软膏对烫伤后常见的感染菌绿脓肝菌、金黄色葡萄球菌的保护作用,并与阳性对照药磺胺嘧啶银霜、磺胺嘧啶锌软膏进行对比。方法取18~22克小鼠,在麻醉下将其尾部造成烫伤,然后再分别将其尾部没入绿脓肝菌和金黄色葡萄球菌液内,使其感染,尾部套上塑料管,将不同浓度的吡哌酸锌,磺胺嘧啶锌软膏及磺胺嘧啶银霜注入管内,封闭,连续观察14d内小鼠死亡现象拼进行显著性检验;结果综合计算法计算各药ED50为:(1)金黄色葡萄球菌,吡哌酸锌软膏ED50=69.84±18.27mg·kg-1,磺胺嘧啶银霜ED50=73.49±19.98mg·kg。(2)绿脓杆菌,吡哌酸锌软ED50=58.16±15.22mg·kg-1,磺胺嘧啶银霜ED50=80.1±2.24mg·kg-1。磺胺嘧啶锌软膏浓度低于0.4%即有明显抗菌作用。结论吡哌酸锋软膏、磺胺嘧啶银霜、磺胺嘧啶软膏均有明显抗菌作用,前两者相比没有显著差异,但吡哌酸锌软膏的抗菌作用比磺胺胺嘧啶锌强。  相似文献   
12.
A 2-year-old German Holstein bull was identified as a carrier of a mutation within the X-chromosomal ED1 gene, which encodes a TNF-related signalling molecule mainly involved in ectodermal development. The clinicopathological appearance was associated with hypotrichosis, hypodontia, and a reduced number of eccrine glands, in addition to chronic rhinotracheitis and partial squamous metaplasia. Furthermore, for the first time in an ED1-deficient animal, a complete lack of respiratory mucous glands was observed. This suggests that the ED1 gene plays a role in the development of mucous glands, the absence of which resembles a feature of X-linked anhidrotic ectodermal dysplasia (ED1) in human patients.  相似文献   
13.
14.
目的 研制鼠抗人GL5 0分子单克隆抗体并对其生物学特性进行初步研究。方法 以天然高表达人GL5 0分子的Daudi细胞为免疫原 ,人GL5 0 L92 9转基因细胞为目的单克隆抗体(McAb)的筛选细胞 ,采用B淋巴细胞杂交瘤技术 ,获得分泌特异性鼠抗人GL5 0分子McAb的杂交瘤细胞株 ;免疫荧光标记和流式细胞术分析McAb识别GL5 0的表达 ;Westernblot检测抗体对特异性细胞膜蛋白的识别 ;台盼蓝 (Trypanblue)染色细胞计数法和MTT法检测McAb对Daudi细胞体外生长的抑制作用 ;3 H TdR法检测抗体对GL5 0 L转基因细胞介导的活化T细胞体外增殖的效应。结果 成功制备 2株分泌特异性抗人GL5 0抗体的杂交瘤细胞株 12B11和 11C4 ;两者皆为IgG2a亚型 ;腹水效价皆在 1∶10 0 0以上 ;12B11、11C4特异性地识别GL5 0分子。 11C4McAb可以明显抑制Daudi细胞在体外的生长 ,并可抑制GL5 0 L转基因细胞介导的活化T淋巴细胞的体外增殖效应。结论 成功获得了 2株特异性鼠抗人GL5 0抗体 ,其中 11C4McAb具有诱导表达GL5 0分子的B淋巴瘤细胞Daudi的体外生长抑制作用 ;在T淋巴细胞体外增殖反应中发挥了重要的调节作用。  相似文献   
15.
大鼠肝抑素纯化及其生物活性的检测   总被引:3,自引:1,他引:3  
孙亚平  刘银坤 《解剖学报》1994,25(3):308-312,T015
用SephadecG-5凝胶过滤层析法,进一步纯化具肝抑素生物活性的大鼠肝蛋白质粗提品,以分离的大鼠再生肝的肝细胞为靶细胞,体外检测各洗脱峰浓缩物对肝细胞增殖的制率结果证明,E峰浓缩物的抑制作用最强,其活性比为粗提品的20倍,SDS聚丙烯酰胺电泳图及蛋白质迁移率测定表明,该浓缩物的主要成分为分子量13.5kD的多肽。本研究对大鼠肝抑素做了初步纯化,验证了该物质在肝再生中起重要调控作用的生物效应。  相似文献   
16.
We report an autopsy case of a pedigree of familial amyloidotic polyneuropathy (FAP) with a mutation of isoleucine-50 transthyretin (ATTR Ser50Ile). A 47-year-old man started developing severe diarrhea and weight loss at age 41 years, followed by urinary incontinence, autonomic-nervous-system abnormalities and serious heart failure; the diagnosis of FAP (ATTR Ser50Ile) was made on the basis of genetic, histochemical and immunohistochemical analysis. Six years after the initial symptoms, he died of septic shock. Autopsy revealed suppurative peritonitis, perforation of the sigmoid colon and marked systemic amyloid deposition. The total amount of amyloid deposited in the heart was greatly increased and was much lower in the thyroid gland and kidneys compared with amyloid deposits in ordinary FAP (ATTR Val30Met). Amyloid deposition in peripheral vessel walls was prominent, particularly in lymphatics and veins. His elder sister, 54 years old, started to develop orthostatic hypotension at age 49 years, followed by dysesthesia, diarrhea and severe congestive heart failure. Endomyocardial biopsy revealed severe TTR–amyloid deposition; ultrastructural examination demonstrated that amyloid fibrils were deposited disproportionately and extended radially around microvessels. These characteristic patterns of systemic amyloid deposition and distinct clinical manifestations, especially in the cardiovascular system, are considered to be a characteristic feature of ATTR Ser50Ile amyloidosis. Received: 31 August 1999 / Accepted: 19 October 1999  相似文献   
17.
ICAM-3/CD50 is a recently described LFA-1 counter receptor that seems to play an important role in the initiation of immune responses. In this study we have examined the expression of ICAM-3/CD50 in a large series of human neoplasms including 101 Non-Hodgkin's lymphomas (NHL), 26 Hodgkin's disease, and 38 solid tumors to define the distribution patterns of this molecule in malignant neoplasms and their possible correlation with clinical and pathological characteristics of the patients. In NHL, ICAM-3/CD50 was expressed in almost all the tumors with a tendency to be lost in high grade lymphomas. Reed-Sternberg cells and their variants in Hodgkin's disease were always negative independently of the histological subtype of the disease. No expression was observed in tumor epithelial cells of the 38 solid tumors examined. Strong endothelial cell staining was observed in 31% of the NHL and 31% of Hodgkin's disease. ICAM-3 expression in these cases was restricted to small tumor vessels. ICAM-3 expression in endothelial cells of NHL was significantly more frequent in high grade (40%) than in low grade lymphomas (14%) (p=0.012). In addition, tumor vessels were also positive in 29% of solid rumors independently of the histological type. No correlation was observed between ICAM-3 expression in tumor or endothelial cells and other clinical and pathological characteristics of the patients. These findings indicate that ICAM-3 expression in human tumors is restricted to hematological neoplasms with a tendency to be lost in high grade lymphomas and Hodgkin's disease. ICAM-3 is also expressed by endothelial cells from tumor-associated neovascularization in both lymphoid and solid tumors.  相似文献   
18.
Monoclonal antibodies were produced against the histidine-rich protein of Plasmodium lophurae and tested for reactivity with Plasmodium falciparum antigens. One anti-histidine-rich protein monoclonal antibody showed immunological cross-reactivity with polypeptides of P. falciparum synthesized in vivo and in vitro.  相似文献   
19.
A comparison of the bronchodilator activity of Sch 1000 and salbutamol.   总被引:6,自引:0,他引:6  
The effects of the beta 2-adrenergic agonist, salbutamol, 200 mug, and the cholinergic antagonist, Sch 1000, 40 mug, have been compared in 25 asthmatic patients using a single dose, double-blind, crossover trial design. Salbutamol aerosol produces a greater degree of bronchodilatation than Sch 1000 aerosol during the initial three hours following drug administration. There is no significant difference in the bronchodilator effects of the two drugs in the interval four to eight hours after drug administration. Nonatopic patients showed less difference in bronchodilator response to each of the two drugs than atopic patients. Neither drug showed any significant adverse effect on blood pressure, pulse rate, or electrocardiogram. In six asthmatic patients the effect of the combination of salbutamol, 200 mug, and Sch 1000, 40 mug, was evaluated. The combination produced a longer duration of bronchodilatation than either drug alone when compared to placebo.  相似文献   
20.
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