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   17901篇
  免费   972篇
  国内免费   414篇
耳鼻咽喉   83篇
儿科学   316篇
妇产科学   242篇
基础医学   4153篇
口腔科学   396篇
临床医学   2072篇
内科学   2899篇
皮肤病学   311篇
神经病学   610篇
特种医学   398篇
外国民族医学   9篇
外科学   712篇
综合类   2626篇
现状与发展   1篇
预防医学   1715篇
眼科学   114篇
药学   863篇
中国医学   334篇
肿瘤学   1433篇
  2024年   6篇
  2023年   70篇
  2022年   217篇
  2021年   336篇
  2020年   353篇
  2019年   384篇
  2018年   464篇
  2017年   411篇
  2016年   461篇
  2015年   511篇
  2014年   1005篇
  2013年   929篇
  2012年   969篇
  2011年   1275篇
  2010年   934篇
  2009年   996篇
  2008年   981篇
  2007年   1060篇
  2006年   975篇
  2005年   948篇
  2004年   834篇
  2003年   793篇
  2002年   688篇
  2001年   647篇
  2000年   551篇
  1999年   440篇
  1998年   400篇
  1997年   376篇
  1996年   297篇
  1995年   301篇
  1994年   259篇
  1993年   154篇
  1992年   98篇
  1991年   72篇
  1990年   26篇
  1989年   9篇
  1985年   8篇
  1984年   8篇
  1983年   8篇
  1982年   13篇
  1981年   3篇
  1980年   8篇
  1979年   2篇
  1978年   1篇
  1977年   2篇
  1976年   1篇
  1975年   2篇
  1973年   1篇
排序方式: 共有10000条查询结果,搜索用时 93 毫秒
71.
P53基因突变与宫颈癌关系的研究   总被引:1,自引:0,他引:1  
目的:通过对宫颈癌P53基因7-8外显子突变的研究,探讨该基因的突变与宫颈癌的发生、发展之间的关系。方法:本文运用聚合酶链式反应(PCR)方法,对宫颈癌组织P53的7-8外显子是突变进行了试验,并与非肿瘤的慢性宫颈炎(宫颈糜烂、宫颈息肉)组织作了对照。结果:10例宫颈癌标本中有7例出现了P537-8外显子的突变,阳性率高;而8例作为对照的宫颈炎标本仅有1例出现可疑的阳性结果。结果:试验结果说明,宫  相似文献   
72.
目的:寻找适合于临床PCR检测结核杆菌DNA简单、快速、有效、经济的细菌裂解方法。方法:采用11种细菌裂解剂对相同数量的结核分枝杆菌进行裂解,裂解上清液直接用于PCR扩增,结果:1%TritonX-100,1%NP40,1%Teween20、和1%OP四种裂解剂的裂解液可直接扩增出结核分枝杆菌DNA;SDS,NaOH,十二烷基肌酸钠等裂解剂的裂解液直接用于PCR扩增均为阴性。结论:1%的Tritonx-100,NP40、Teween20和乳化剂OP裂解细菌效果好,又不抑制PCR反应,适合于作为临床PCR检测结核杆菌的裂解剂。  相似文献   
73.
聚合酶链反应在鼠疫菌检测中的应用 研究   总被引:2,自引:0,他引:2  
本文采用聚合酶链反应(PCR)技术,通过扩增鼠疫菌9.5kb质粒pla基础上一个478bl片段,用于鼠疫菌检测,被试的45株鼠疫菌扩增产物经琼脂糖凝胶电泳分析均呈现单一DNA带,其分子量大小与预期结果符合。而假结核菌和一株缺6MD质粒鼠疫菌未见扩增带,洽部实验可在4h内完成。本法具有快速、特异、敏感等优点,可用于不同生态型鼠疫菌的快速诊断和流行病学研究.  相似文献   
74.
Clinical and diagnostic DNA laboratories must maintain a large inventory of DNA probes for use in hybridization studies. The preparation of plasmid DNA and isolation of DNA fragments for use as probes in both expensive and time consuming. We present here a rapid and relatively inexpensive method of producing large amounts of DNA fragments from stocks, using the polymerase chain reaction (PCR). Our experience over the past year using this technique has been very positive and we believe many laboratories could benefit by employing such a labor-saving approach to maintaining DNA probes. The technique uses the bacteriophage M13 DNA sequencing primers to amplify cloned inserts contained in commonly used plasmid vectors. As examples, we illustrate the use of DNA produced in this manner as probes for linkage analysis of the fragile X syndrome and for detection of deletions in the Duchenne muscular dystrophy gene. We have also found that at least two probes can be amplified in the same PCR reaction, allowing the detection of two different restriction fragment length polymorphisms (RFLP) simultaneously. It should be possible for laboratories to devise strategies particular to their individual needs using more than one DNA probe produced in the same PCR reaction to detect RFLP's. Such strategies would need only to consider that the predicted alleles of the multiple polymorphisms do not migrate to the same position during electrophoresis. Stocks of single or multiple probes produced by the PCR could then be maintained for more rapid Southern analyses.  相似文献   
75.
尖锐湿疣患者人乳头瘤病毒的基因分型   总被引:2,自引:0,他引:2  
目的 探索尖锐湿疣患者人乳头瘤病毒的基因分型。方法 PCR方法检测HPV6/11型、HPV16/18型DNA。结果 检测尖锐湿疣患者100例,对其中35例进行组织活检,阳性检出率为91.4%(32/35),阳性检出中,HPV6/11型26例(81.2%),HPV16/18型3例(9.4%),HPV6/11 HPV16/18型3例(9.4%);对其中65例进行宫颈抹片检测,阳性检出率为92.3%(60/65),阳性检出中,HPV6/11型41例(68.3%),HPV16/18型12例(20.0%),HPV6/11 HPV16/18型7例(11.7%)。结论 尖锐湿疣患者人乳头瘤病毒感染以HPV6/11型为主,HPV16/18型在宫颈处感染率高于其它处组织。  相似文献   
76.
77.
78.
Abstract: The fate of polymorphonuclear neutrophilic granulocytes (PMN) after their mobilization from the bone marrow of healthy individuals is not clearly understood. It has been suggested that there is a continuous utilization of these cells in widespread, subclinical inflammatory foci, where they are ultimately degraded. The goal of the present experiments was to determine whether an alternative ecotaxis (“homing”) exists, namely sequestration and degradation of PMN by mononuclear phagocytes exposed to the bloodstream in the liver, spleen and bone marrow. Blood PMN were collected from donor rats, labelled with 51Cr, and injected i.v. into 2 syngeneic rats, one of them having an induced sterile peritonitis. After various time intervals up to 18 h, the rats were killed and exsanguinated. As expected, we found cell-bound radioactivity in the inflamed peritoneal cavities, and also a high amount of radioactivity in liver, spleen, and bone marrow. The bone marrow uptake of PMN appeared to be much lower in the inflammation rats than in the normal controls. These findings were confirmed in PMN transfer experiments using PVG rats congenic for the RT7 alloantigenic system. Here, transfused blood leukocytes were traced with fluorescent, monoclonal HIS41 antibodies and flow cytometry. A possible corticosteroid effect on the bone marrow sequestration could not be substantiated. Uptake and degradation of PMN takes place in organs containing phagocytes exposed to the bloodstream. Sequestration of PMN in the bone marrow is apparently down-regulated in inflammatory states, perhaps increasing the PMN availability to inflamed tissue.  相似文献   
79.
检测25例脑肿瘤中抑制癌基因P53突变情况。突用复合PCR,聚合酶链反应-=单链构象多态性分析法,统计学处理采用X^2检验。结果:P53基因总的突变率为44.0%,其中第5外显子突变率为28.0%,第6外显子突变率12.0%,第7外显子突变率为12.0%,第8外显子突变率16.0%;病理分级Ⅱ级及其以上突变为72.7%,  相似文献   
80.
Thirty-eight Swedish patients with chronic hepatitis C were randomly assigned to receive either 3 million units (MU) or 5MU of human lymphoblastoid interferon-α-n1 (Wellferon) three times per week for either 6 or 12 months. The patients were monitored biochemically, histologically and by quantitative polymerase chain reaction for circulating HCV RNA, during therapy and for the following year. Overall, 22 (58%) of the patients lost detectable hepatitis C virus (HCV) viraemia during therapy but eight of these patients relapsed during follow-up, leaving 14 (37%) sustained responders. Patients infected with HCV non-type 1 genotypes were significantly more likely to achieve a sustained response than were those infected with HCV type 1 (63% vs 10.5%, P =0.001). Sustained virological responses were also associated with lower pretreatment viraemia level, younger age, absence of cirrhosis and the higher interferon dosage regimens but these associations failed to reach statistical significance. In 97% of patients there was concordance between virological and biochemical responses, and a statistically significant ( P =0.005) improvement in the Knodell histological activity index was observed in the virological sustained responders.  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