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   446篇
  免费   31篇
  国内免费   2篇
耳鼻咽喉   3篇
儿科学   47篇
妇产科学   11篇
基础医学   71篇
口腔科学   12篇
临床医学   45篇
内科学   88篇
皮肤病学   2篇
神经病学   65篇
特种医学   6篇
外科学   58篇
综合类   5篇
一般理论   2篇
预防医学   23篇
眼科学   1篇
药学   12篇
肿瘤学   28篇
  2023年   2篇
  2022年   6篇
  2021年   14篇
  2020年   5篇
  2019年   14篇
  2018年   19篇
  2017年   9篇
  2016年   12篇
  2015年   13篇
  2014年   21篇
  2013年   33篇
  2012年   41篇
  2011年   44篇
  2010年   19篇
  2009年   20篇
  2008年   23篇
  2007年   15篇
  2006年   32篇
  2005年   21篇
  2004年   18篇
  2003年   27篇
  2002年   16篇
  2001年   2篇
  1999年   5篇
  1998年   5篇
  1997年   5篇
  1996年   5篇
  1995年   7篇
  1994年   6篇
  1992年   3篇
  1991年   1篇
  1990年   1篇
  1989年   3篇
  1988年   1篇
  1985年   1篇
  1984年   2篇
  1981年   1篇
  1980年   1篇
  1979年   1篇
  1978年   1篇
  1975年   1篇
  1974年   1篇
  1966年   1篇
  1940年   1篇
排序方式: 共有479条查询结果,搜索用时 15 毫秒
1.
2.
Cationic block copolymers spontaneously assemble via electrostatic interactions with DNA molecules in aqueous solution giving rise to micellar structures that protect the DNA from enzymatic degradation both in vitro and in vivo. In addition, we have previously shown that they are safe, not immunogenic and greatly increased antigen-specific CTL responses following six intramuscular inoculations of a very low dose (1 μg) of the vaccine DNA as compared to naked DNA. Nevertheless, they failed to elicit detectable humoral responses against the antigen. To gain further insight in the potential application of this technology, here we show that a shorter immunization protocol based on two DNA intramuscular inoculations of 1 μg of DNA delivered by these copolymers and a protein boost elicits in mice broad (both humoral and cellular) and long-lasting responses and increases the antigen-specific Th1-type T cell responses and CTLs as compared to priming with naked DNA. These results indicate that cationic block copolymers represent a promising adjuvant and delivery technology for DNA vaccination strategies aimed at combating intracellular pathogens.  相似文献   
3.
Thirteen infants, 10 with A-O and 3 with B-O hemolytic disease of the newborn (ABO-HDN), were treated with synthetic A or B blood group trisaccharides (ATS, BTS) which cause dissociation of maternal antibody bound to infant red cells. The clinical outcome was compared with that of a control group of 21 infants treated with phototherapy during the preceding year. Exchange transfusion was required in 2 out of 13 infants in the experimental group and in 7 in the control group. A randomized prospective controlled study is necessary to confirm these results.  相似文献   
4.
Nitric oxide (NO) is a candidate retrograde messenger in long-term potentiation (LTP). The NO metabolic pathway is expressed in the cerebellar granule cell layer but its physiological role remained unknown. In this paper we have investigated the role of NO in cerebellar mossy fiber-granule cell LTP, which has postsynaptic N-methyl-d-aspartate (NMDA) receptor-dependent induction. Pre- and postsynaptic current changes were simultaneously measured by using extracellular focal recordings, and NO release was monitored with an electrochemical probe in P21 rat cerebellar slices. High-frequency mossy fiber stimulation induced LTP and caused a significant NO release (6.2 +/- 2.8 nM; n = 5) in the granular layer that was dependent on NMDA receptor as well as on nitric oxide synthase (NOS) activation. Preventing NO production by perfusing the NOS inhibitor 100 microM NG-nitro-l-arginine (L-NNA), blocking extracellular NO diffusion by 10 microM MbO2, or inhibiting the NO target guanylyl cyclase (sGC) with 10 microM 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-dione (ODQ) prevented LTP. Moreover, the NO donor 10 microM 2-(N,N-diethylamino)-diazenolate-2-oxide.Na (DEA-NO) induced LTP, which was mutually occlusive with LTP generated by high-frequency stimulation, prevented by ODQ, and insensitive to NMDA channel blockade (50 microM APV + 25 microM 7-Cl-kyn) or interruption of mossy fiber stimulation. Thus NO is critical for LTP induction at the cerebellar mossy fiber-granule cell relay. Interestingly, LTP manipulations were accompanied by consensual changes in the presynaptic current, suggesting that NO acts as a retrograde signal-enhancing presynaptic terminal excitability.  相似文献   
5.
6.
Paracetamol (acetaminophen) is one of the most popular and widely used drugs for the treatment of pain and fever in children. This drug has multiple mechanisms of action, but its pharmacodynamic is still not well known. The central nervous system is the main site of action and it mirrors the paracetamol effect compartment. The recommended dosages and routes of administration should be different whether paracetamol is used for the treatment of pain or fever. For example, the rectal route, while being efficacious for the treatment of fever, should be avoided in pain management. Paracetamol is a safe drug, but some clinical conditions and concomitant drugs, which are frequent in clinical practice, may increase the risk of paracetamol toxicity. Therefore, it is important to optimize its administration to avoid overdoses and maximize its effect. The principal mediator of the paracetamol toxicity is the N-acetyl-p-benzo-quinone imine (NAPQI), a toxic product of the paracetamol metabolism, which could bind cysteine groups on proteins forming paracetamol–protein adduct in the liver. Conclusion: Although frequently prescribed, the concept of “effect compartment concentration” and the possible co-factors that could cause toxicity at recommended doses are not familiar to all pediatricians and general practitioners. We reviewed the literature concerning paracetamol mechanisms of action, we highlighted some relevant pharmacodynamic concepts for clinical practice, and we summarized the possible risk factors for toxicity at therapeutic dosages.  相似文献   
7.
In Europe, the red fox (Vulpes vulpes) is considered the reservoir of Angiostrongylus vasorum, nematode residing in the pulmonary arteries and right heart of dogs and many species of wild carnivores. Italy is considered one of the European countries where this nematode is actually spreading. Between May 2007 and November 2013, 62 foxes found dead in Central Italy were necropsied. Right heart and pulmonary arteries were opened and checked for the presence of adult parasites. Impression smears from sectioned lungs were examined for the presence of first-stage larvae, and samples of lungs were processed for histological examination. In order to detect eventual disseminated infections, samples of heart, pulmonary lymph nodes, liver, kidneys, and brain of foxes positive for A. vasorum at necropsy or lungs histological examination were processed for histological examination. An overall prevalence of 43.5 % was recorded. Light, mild, and severe lung lesions were detected in 33.3, 22.2, and 25.9 % of infected animals, respectively. Severe lesions were more frequent in animals younger than 12 months. In five infected foxes (18.5 %), no gross lesions were observed, while for three animals, angiostrongylosis was considered the cause of death. A case of disseminated angiostrongylosis was detected and another one was suspected. This is the firs report of disseminated angiostrongylosis in the fox.  相似文献   
8.
IntroductionSince the first publication of Cloninger's psychobiological model of personality, the relationship between temperament and character dimensions and psychiatric disorders has been widely studied. The exact nature of this interaction, however, is still unclear. Different models have been proposed (state-dependency, vulnerability, continuous spectrum etc).ObjectiveTo analyze the relationship between temperament and character dimensions with depression and panic disorder.MethodSystematic review on interventional studies published up until December 2011 on MEDLINE and ISI databases. Also, a brief review on genetic studies is hereby undertaken, aiming to discuss the gene-environment interaction in relation to this topic.Results:Thirteen studies were included: 10 related to depression and 3 to panic disorder (or unspecific anxiety symptoms). All of them showed association between high harm avoidance (HA) and low self-directedness (SD) with depression and anxiety symptoms. Longitudinal studies demonstrated that these traits may not be just state-dependent.Conclusions:HA and SD dimensions are associated with both the occurrence of depressive and anxiety symptoms. There is also some evidence to suggest that high HA and low SD indicates susceptibility to depression. Longitudinal studies are not sufficient to affirm the same about panic disorder up to the present moment.  相似文献   
9.
10.
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