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   15885篇
  免费   1331篇
  国内免费   1220篇
耳鼻咽喉   106篇
儿科学   186篇
妇产科学   230篇
基础医学   1911篇
口腔科学   343篇
临床医学   2280篇
内科学   2561篇
皮肤病学   124篇
神经病学   859篇
特种医学   808篇
外国民族医学   11篇
外科学   1694篇
综合类   2397篇
现状与发展   3篇
一般理论   3篇
预防医学   871篇
眼科学   365篇
药学   1564篇
  12篇
中国医学   808篇
肿瘤学   1300篇
  2024年   50篇
  2023年   259篇
  2022年   657篇
  2021年   866篇
  2020年   577篇
  2019年   525篇
  2018年   562篇
  2017年   443篇
  2016年   455篇
  2015年   680篇
  2014年   864篇
  2013年   714篇
  2012年   1093篇
  2011年   1215篇
  2010年   712篇
  2009年   660篇
  2008年   795篇
  2007年   783篇
  2006年   748篇
  2005年   774篇
  2004年   493篇
  2003年   501篇
  2002年   441篇
  2001年   345篇
  2000年   392篇
  1999年   453篇
  1998年   305篇
  1997年   289篇
  1996年   242篇
  1995年   242篇
  1994年   167篇
  1993年   129篇
  1992年   143篇
  1991年   103篇
  1990年   95篇
  1989年   89篇
  1988年   84篇
  1987年   96篇
  1986年   71篇
  1985年   70篇
  1984年   34篇
  1983年   25篇
  1982年   23篇
  1981年   22篇
  1980年   28篇
  1979年   13篇
  1978年   15篇
  1977年   25篇
  1976年   12篇
  1975年   9篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
柯萨奇病毒诱发实验性多发性肌炎的初步研究   总被引:4,自引:0,他引:4  
分别用不同量的柯萨奇病毒B1、2、3感染和兔肌匀浆加完全弗氏佐剂免疫正常豚鼠;拟建立多发性肌炎模型。结果发现:0.1ml毒力为10-5TCID50柯萨奇病毒B1感染豚鼠组,3周后出现多发性肌炎症状。肌酶谱异常与其它组有明显差异,病理检查证实为多发性肌炎改变。单纯兔肌匀浆免疫对照组未发病。提示柯萨奇病毒B1感染及感染的病毒量与多发性肌炎的发病相关  相似文献   
12.
13.
Y Huang  S Hou  R Xie  Z Zhuang  F Wang  N Zhong 《中国中药杂志》1997,22(11):667-71, 703
The extraction, purification, pharmacological experiments and chemical analysis of anti-hepatoma active principles of Radix Aconiti Kusnezoffii have been studied. The results show that the medicinal material Radix Aconiti Kusnezoffii is efficacious in inhibiting hepatoma, and the active principles are mainly made up of poisonous ester alkaloids. The liver targeting delivery system will be the first choice for its anti-hepatoma preparation, and the effective component AY3a is fit for the preparation of targeted microspheres.  相似文献   
14.
本文报告了6~9个月胎儿长骨的化学成分的测定结果及其组织特点并与成人作了比较。自1985~1987年共进行了胎儿骨移植40例,随访38例,经4~20个月(平均10.3个月)的临床观察,证实胎儿骨移植后“爬行替代”快,骨诱导能力强,排斥反应不明显,笔者认为这些特点与胎骨的形态结构及化学成分有关。胎儿骨的采取和贮存简便,应用方便,易于推广和普及。  相似文献   
15.
Response properties of reticulospinal neurons in the lateral reticular nucleus (LRN) area to natural cutaneous stimulation were investigated systematically in 45 urethane-anesthetized rats by using extracellular recording techniques. A total of 64 neurons were tested with peripheral stimuli, of which 19 were responsive only to noxious stimuli; 7 responsive to both noxious and non-noxious stimuli; 4 responsive only to non-noxious stimuli; and 34 not responsive to any cutaneous stimuli. Both the noxious and non-noxious receptive fields were large and bilateral. Among the neurons responding to noxious stimuli, the majority (72%) was excited. This study provides evidence that some reticulospinal neurons in the rat LRN area are involved in the mechanisms of nociception.  相似文献   
16.
Summary: In this work, blends of monomer casting polyamide 6 (MCPA6) and acrylonitrile‐butadiene‐styrene (ABS) were successfully prepared by in situ polymerization via the application of ε‐caprolactam as a reactive solvent. The morphology and thermal properties of MCPA6/ABS were investigated by means of wide angle X‐ray diffraction (WAXD), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM), respectively. The domain sizes of the ABS phase in MCPA6/ABS blends were much finer than those in corresponding polyamide 6 (PA6)/ABS blends prepared by simple melt blending. With an increased amount of ABS in MCPA6, the melt enthalpy (ΔHf), the rate of crystallization (Tc) and the degree of crystallinity (Xc(DSC)) of MCPA6 in MCPA6/ABS blends were all decreased. The degree of supercooling (ΔTd) showed a contrary trend. However, the melting temperatures of these blends were almost unchanged. All the results could be attributed to in situ polymerization and the hydrolysis reaction of ABS that occurred during the polymerization process. Furthermore, WAXD results showed that only α‐form crystals existed in the MCPA6/ABS blends, despite the ABS content and heat treatment.

SEM micrograph of the fractured surface of an MCPA6/ABS blend with an ABS content of 20 wt.‐% (×10 000).  相似文献   

17.
Immunoregulatory effects of morphine on human lymphocytes.   总被引:7,自引:0,他引:7       下载免费PDF全文
It is now well established that parenteral drug abuse is a significant risk factor for contracting human immunodeficiency virus type 1 (HIV-1) infection and subsequently developing AIDS. Earlier studies have shown that morphine can modulate various immune responses and therefore support the premise that morphine is a cofactor in susceptibility to and progression of HIV infection. Dysregulation of interferon (IFN) production, nonspecific apoptosis of T cells, and the immune response to soluble HIV gene products have been associated with potential mechanisms of pathogenesis in HIV disease. The present study was undertaken to examine the immunomodulatory role of morphine on HIV protein-induced lymphocyte proliferative responses, Sendai and Newcastle disease virus-induced alpha IFN (IFN-alpha) and IFN-beta production by lymphocytes and fibroblast cells, respectively, and induction of apoptosis of normal lymphocytes in vitro. Our results demonstrate that HIV protein-induced human lymphocyte proliferative responses were significantly inhibited by morphine in a dose-dependent manner. Furthermore, morphine significantly inhibited both IFN-alpha and IFN-beta production by normal lymphocytes and fibroblasts but induced apoptosis of normal lymphocytes. Inhibition of IFN-alpha production by morphine could be reversed by the opiate receptor antagonist naloxone. This suggests that the immunomodulatory effects of morphine are mediated through the opioid receptor. These studies support a role of morphine as a cofactor in the pathogenesis of HIV infection and describe some of the possible pathologic mechanisms which underlie the immunoregulatory effects of morphine.  相似文献   
18.
目的 探讨肝素酶(heparanase)和碱性成纤维细胞生长因子(bFGF)在人非小细胞肺癌(NSCLC)组织中表达的临床意义及其与肺癌转移和预后的关系。方法 采用免疫组织化学、原位杂交和Western blot方法,检测115例人NSCLC石蜡切片和45例新鲜肺癌及对应癌旁正常组织中肝素酶和bFGF的表达情况。采用χ^2检验、t检验、生存曲线和Cox比例风险回归等方法分析肝素酶和bFGF分别表达及共表达的意义。结果 免疫组织化学染色证实肝素酶(91/115)和bFGF(89/115)主要表达在癌细胞质和(或)细胞膜中,在正常肺泡上皮和支气管上皮中则呈阴性表达。Western blot也证实肝素酶在肺癌中的表达明显增高(P=0.041)。统计分析结果显示:肝素酶和bFGF的表达具有明显的一致性(P:0.0001),二者单独表达和共表达均与肺癌的分期、血管侵袭、淋巴结转移、微血管密度和预后有关,其中,二者共表达时与分期和微血管密度的相关性更显著;另外,bFGF还与肺癌的分化程度有关。多因素分析结果显示,肺癌的分化程度、血管浸润、淋巴结转移和bFGF的表达可以作为判断肺癌预后的危险因素,但肝素酶不是影响预后的独立因素。结论 肝素酶和bFGF均与肺癌的转移、血管生成和预后密切相关。  相似文献   
19.
Saccharomyces cerevisiae ATS1 (-tubulin suppressor 1) was originally identified as a high-copy suppressor of class two -tubulin mutations and was proposed to have a regulatory role in coordinating the microtubule state with the cell cycle. Here, we show that Ats1p interacts with Nap1p, a cytoplasmic protein that regulates the activity of the Cdc28p/Clb2p complex. Loss of Nap1p results in a delayed switch from polar to isotropic bud growth. The delayed switch results in elongated buds. Nap1p and Ats1p interact in two-hybrid and co-immunoprecipitation assays. Both nap1 and ats1 cells have a Clb2p-dependent elongated bud morphology. Deletion of ATS1 partially suppresses the elongated bud morphology and benomyl resistance of nap1 mutants. Our results suggest Ats1p might regulate coordination of the microtubule state with the cell cycle through an interaction with Nap1p.Communicated by S. Hohmann  相似文献   
20.
National Taiwan University College of Medicine (NTUCM) introduced small groups of teaching and basic-clinical integrated courses for medical students in 1992. By using computer network and multimedia techniques, this study tried to overcome barriers to learning in small group teaching. The Department of Medical Informatics of NTUCM established campus networking and computer classrooms and provided Internet and intranet network services including mail, netnews, bulletin board systems (BBS), world wide web (WWW), gopher, ftp and local file servers. To implement an interactive learning environment, the authors first tried mail lists, newsgroups and BBS. Next an integrated learning system prototype on the WWW was developed to provide functions including online syllabus, discussion boards simulated to BBS, online talk, interactive case studies, virtual classroom with video on demand (VOD) and Internet medical resources. The results showed that after the medical students completed the required course of medical informatics and had good network access using a network to communicate with each other became a daily practice. In the future, the system will extend to the tutoring of clinical practice and continuing medical education. The authors expect a national medical education network and more international cooperation and exchange.  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