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   432篇
  免费   16篇
  国内免费   6篇
儿科学   2篇
妇产科学   4篇
基础医学   68篇
口腔科学   7篇
临床医学   24篇
内科学   82篇
皮肤病学   1篇
神经病学   15篇
特种医学   5篇
外科学   19篇
综合类   38篇
预防医学   102篇
眼科学   4篇
药学   12篇
肿瘤学   71篇
  2023年   1篇
  2021年   5篇
  2020年   6篇
  2019年   14篇
  2018年   13篇
  2017年   5篇
  2016年   7篇
  2015年   8篇
  2014年   16篇
  2013年   15篇
  2012年   23篇
  2011年   31篇
  2010年   28篇
  2009年   41篇
  2008年   31篇
  2007年   37篇
  2006年   29篇
  2005年   20篇
  2004年   18篇
  2003年   16篇
  2002年   9篇
  2001年   6篇
  2000年   2篇
  1999年   9篇
  1998年   4篇
  1997年   8篇
  1996年   3篇
  1995年   3篇
  1994年   3篇
  1993年   3篇
  1992年   5篇
  1990年   1篇
  1989年   2篇
  1987年   2篇
  1986年   4篇
  1985年   1篇
  1984年   5篇
  1983年   7篇
  1982年   3篇
  1981年   4篇
  1979年   1篇
  1978年   2篇
  1976年   3篇
排序方式: 共有454条查询结果,搜索用时 15 毫秒
1.
2.
本文在介绍我院研制成的WKZX型微机自控系统的组成及性能基础上,提出了以微处理机为基础的数字自控系统设计及其规律。介绍了应用本装置所研究的几个实例——PWM微机伺服系统和发酵过程参数预值仿真及其控制等。  相似文献   
3.
4.
A single gene copy merozoite surface antigen and immune evasion?   总被引:1,自引:0,他引:1  
During the course of chronic malaria infection antigenic variants of a parasite antigen are expressed and exposed on the surface of infected erythrocyte membranes. There also exists a number of apparently invariant single gene copy blood-stage antigens, exposed or non-exposed, which have been shown to afford immunity under experimental conditions. To determine why the host, presented with invariant 'protective' antigens, is unable to control infections effectively, immunity to a representative single gene copy antigen, the merozoite surface protein 1 (MSP1) was investigated in Plasmodium chabaudi chabaudi AS, a murine model of chronic malaria. Immunization with monoclonal antibody affinity purified native MSP1 resulted in enhanced control of parasitaemia on challenge, irrespective of the parasite inoculum size; challenge with a single parasite, however, suggested that expansion of resistant parasite subpopulations was not occurring. Challenge of mice immunized with recombinant fusion proteins encoding N- or C-terminal regions of the P.c. chabaudi AS MSP1 produced inconsistent effects, often parasitaemias were indistingishable from controls despite significant anti-MSP1 antibody responses. The not unlikely contamination of MSP1 native preparations with erythrocyte (E) components was considered. Immunization with a mixture of the MSP1 C-terminus recombinant polypeptide and a Triton X-100 solubilized lysate of normal E resulted in enhanced control of parasitaemia, however, no effect was seen after administration of either component on its own. Co-immunization of E with the N-terminus polypeptide reversed the inhibition seen, on this occasion with this construct alone.  相似文献   
5.
基于MSP430F149的血氧饱和度检测仪   总被引:6,自引:1,他引:6  
本文根据红光和红外光透过手指动脉血管后的相对最大光强和光强的最大变化量之比来计算血氧饱和度的一般原理推导出实用的计算方法,并结合MSP430F149微处理器低功耗优势,以及丰富的外围资源研制设计的可控增益放大器等,有效地克服了由于个人生理差异而引起的测量信号基线漂移,满足了仪器便携化设计的需求.  相似文献   
6.
经络综合导引治疗仪是根据祖国医学的经络学说和养气功理论,应用呼气启动导引,视觉模型提示和穴位电刺激的多因素共同作用,导引气血沿经络运行。主要用于强化瘫痪肢体的康复。该治疗仪以单片微机为程控中心,通过硬件设计和软件开发,实现了呼气触发,视觉提示和位电刺激同步发,16和电极依次选通和数字化幅度调节等多种功能。  相似文献   
7.
Merozoites of the malaria parasite Plasmodium falciparum possess on their surface proteolytically processed fragments of the merozoite surface protein-1 (MSP1). Secondary processing of one of these fragments, MSP142, always occurs prior to, or at the point of successful erythrocyte reinvasion. It is shown that a product of this secondary processing, MSP133, is shed in the form of a noncovalently-associated complex with a number of other proteins, including the MSP1-derived species MSP138 and MSP183. Secondary processing of MSP142, is inhibited by the chelating agents ethylenediaminetetraacetic acid (EDTA) and ethyleneglycol-bis-(β-aminoethyl ether)-tetraacetic acid (EGTA), and this inhibition is reversible by addition of excess calcium. Secondary processing occurs in preparations of washed, disrupted merozoites, and is inhibited by the protease inhibitors phenylmethylsulphonyl fluoride (PMSF) and diisopropyl fluorophosphate (DFP), indicating that the protease responsible is a membrane-associated serine protease.  相似文献   
8.
硬膜外脊髓电刺激仪的研制   总被引:1,自引:1,他引:1  
临床实验证实硬脊膜外脊髓电刺激(ESCS)与减重步态疗法(PWBT)相结合,能明显提高患者脊髓损伤康复后的行走能力,对运动能量代谢产生显著影响,但相应的神经与生理机制目前尚不清楚.本研究开发研制一种小型低功耗的先进ESCS刺激仪,为ESCS机理的实验研究提供所需的刺激模式.基于印刷电路板工艺,采用聚酰亚胺对银电极触点进行绝缘封装,改进电极的设计.进行ESCS刺激仪性能的动物实验验证,改变电压幅值、频率和波宽等刺激参数,观察实验猫肌肉的抽搐情况.实验结果表明:所研制的小型低功耗ESCS刺激器能提供所需的多通道多模式刺激信号,电池供电和低功耗设计可提供使用安全性,ESCS电极满足柔韧性和生物兼容性要求,可为ESCS和PWBT组合疗法的机理研究提供先进实验手段.  相似文献   
9.
大肠癌p16抑癌基因甲基化及与Dukes分期的关系   总被引:2,自引:0,他引:2  
目的 检测大肠癌患者p16基因启动子CpG区甲基化的改变,探讨其与大肠癌发生、发展和临床资料的关系。方法 采用甲基化特异PCR技术(MSP法)研究58例大肠癌标本p16基因甲基化改变,分析临床病理资料。结果 25例标本(43.1%)呈p16 CpG区甲基化阳性;Dukes C、D期病人p16 CpG区甲基化发生率(75%)明显高于Dukes A、B期病人(13.3%)。结论 p16启动子区甲基化导致p16抑癌基因失活参与了大肠癌的发生和发展;p16甲基化可以作为估计大肠癌病人预后的一个指标。  相似文献   
10.
Two phase I vaccine trials were conducted to test the immunogenicity and safety of a vaccine containing three recombinant malaria antigens from the asexual stage of Plasmodium falciparum. The three antigens are a fragment of MSP1 (190LCS.T3); MSP2 and a portion of RESA and were formulated in Montanide ISA720 adjuvant. These trials investigated the dose response of each antigen for eliciting both antibody and T-cell responses and the immunogenicity of a mixture of the antigens compared with the antigens injected separately. All three antigens elicited both antibody and T-cell responses. Strong T-cell responses were observed with 190LCS.T3 and RESA with stimulation indices exceeding 100 for peripheral blood leucocytes in some individuals. The antibody responses were generally weak. The human antibody responses observed with MSP2 in Montanide ISA720 were not significantly different from those obtained in an earlier trial which used MSP2 with alum as the adjuvant. No antigenic competition was observed: volunteers receiving a mixture of antigens had similar responses to those receiving the three antigens at separate sites. Tenderness and pain at the injection site were common over the first few days following immunization. In some volunteers, especially those receiving the highest doses tested, there was a delayed reaction at the injection site with pain and swelling occurring approximately 10 days after injection.  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