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   678篇
  免费   33篇
  国内免费   15篇
耳鼻咽喉   1篇
儿科学   3篇
妇产科学   3篇
基础医学   62篇
口腔科学   7篇
临床医学   102篇
内科学   26篇
皮肤病学   110篇
神经病学   142篇
特种医学   11篇
外科学   7篇
综合类   124篇
预防医学   74篇
眼科学   4篇
药学   45篇
  1篇
中国医学   4篇
  2024年   2篇
  2023年   8篇
  2022年   20篇
  2021年   32篇
  2020年   14篇
  2019年   10篇
  2018年   12篇
  2017年   18篇
  2016年   29篇
  2015年   39篇
  2014年   42篇
  2013年   44篇
  2012年   54篇
  2011年   49篇
  2010年   39篇
  2009年   33篇
  2008年   32篇
  2007年   19篇
  2006年   28篇
  2005年   30篇
  2004年   34篇
  2003年   17篇
  2002年   13篇
  2001年   15篇
  2000年   5篇
  1999年   4篇
  1998年   7篇
  1997年   8篇
  1996年   6篇
  1995年   5篇
  1994年   3篇
  1993年   6篇
  1992年   7篇
  1991年   2篇
  1990年   6篇
  1989年   3篇
  1988年   3篇
  1987年   9篇
  1985年   8篇
  1984年   4篇
  1983年   2篇
  1982年   2篇
  1981年   1篇
  1980年   1篇
  1970年   1篇
排序方式: 共有726条查询结果,搜索用时 15 毫秒
1.
目的 构建梅毒螺旋体 (Treponemapallidum ,Tp)外膜蛋白Gpd基因的原核表达载体 ,检测其表达产物的免疫原性 ,并比较梅毒螺旋体各菌株Gpd基因序列的同源度。方法 从TpNichols株基因组模板中PCR扩增Gpd基因 ,与GenBank登录的序列做blast比较 ,定向克隆构建原核表达重组体pET2 8b( + ) -Gpd ,转入大肠杆菌ril表达菌 ,SDS -PAGE分析重组蛋白的表达 ,Western -blot检测重组蛋白的免疫原性。结果 载体上所连目的基因片段序列与GenBank登录的Nichols株Gpd基因序列完全一致 ,同其他病原性密螺旋体菌株登陆序列比较同源度为 98%~ 1 0 0 %。SDS -PAGE检测诱导产物显示有一Mr约为 41kDa的特异蛋白带 ,免疫印迹技术检测其能与梅毒阳性标准血清反应。结论 Tp原核表达重组体pET2 8b( + ) -Gpd成功构建 ,且能够在ril表达菌中融合表达 ,为进一步研究该蛋白的生物学功能奠定了一定的实验基础。  相似文献   
2.
In the current era of functional surgery for movement disorders, deep brain stimulation (DBS) of the globus pallidus internus (GPi) is emerging as the favoured intervention for patients with dystonia. Here we report our results in 20 patients with medically intractable dystonia treated with GPi stimulation. The series comprised 14 patients with generalized dystonia and six with spasmodic torticollis. Although comparisons were limited by differences in their respective neurological rating scales, chronic DBS clearly benefited both patient groups. Data conveying the rate of change in neurological function following intervention are also presented, demonstrating the gradual but progressive and sustained nature of improvement following stimulation of the GPi in dystonic patients.  相似文献   
3.
A real-time PCR assay with a Taqman probe was developed that targeted the polA gene of Treponema pallidum. The test was validated using an analytical panel (n = 140) and a clinical panel of genital samples (n = 112) from patients attending a sexually transmitted infections clinic. High sensitivities and specificities of 94-100% were achieved using two real-time PCR platforms, the Rotor-Gene and the iCycler. The assay can be completed within 2 h, enabling reporting in <8 h. This fast and robust assay is suitable for implementation in routine laboratories for diagnosing primary syphilis.  相似文献   
4.
The nucleus accumbens and ventral pallidum receive dopamine (DA) projections from the mesencephalon. Although DA inputs to the nucleus accumbens are implicated in both locomotion and reward processes, little is known of the behavioural significance of DA in the ventral pallidum. These studies examined the effects of -amphetamine injected into the nucleus accumbens or ventral pallidum on locomotor activity and responding for a conditioned reward (CR). In the nucleus accumbens -amphetamine dose dependently (1, 3 and 10 μg) increased locomotion within 5–10 min of injection. Intra-ventral pallidum microinjections of -amphetamine also increased activity in this dose range, but the effect occurred with a longer latency (5–20 min). The magnitude of the response evoked by ventral pallidum injections was lower than that evoked by nucleus accumbens injections. The GABAA antagonist picrotoxin (0.1 μg) stimulated activity when injected into the ventral pallidum but not the nucleus accumbens, providing a pharmacological dissociation between the two injection sites. In the CR studies, -amphetamine injected into both sites potentiated responding for a CR previously paired with food delivery, without altering responding on an inactive lever. Picrotoxin injected into the ventral pallidum reduced responding and abolished the selectivity of responding for CR. The results show that DA release in the ventral pallidum enhances locomotion and responding for a CR, providing evidence that DA in the ventral pallidum plays a significant role in the mediation of the effects of -amphetamine. The failure of picrotoxin to elevate responding for CR despite increasing locomotor activity indicates that pharmacologically-induced blockade of GABAA receptors in the ventral pallidum disrupts goal-directed responding.  相似文献   
5.
Treponema pallidum subsp. pallidum is the causative a gents of syphilis. Presently, the annual infection rate ofdomestic and international syphilis remains rather high [1,2]. Apart from the serious nature of the disease itself, anumber of studies sugg…  相似文献   
6.
7.
The ventral pallidum is the output structure of the nucleus accumbens in the ventral corticostriato-thalamocortical loop. Information processing in this loop is critically involved in motor behavior and reinforcement. The ventral pallidum receives a direct dopaminergic input from the ventral tegmental area, but also glutamatergic input from cortical and limbic areas. It has been assumed that dopamine release in the VP is indeed modulated by glutamate. The present study investigated the effects of NMDA receptor blockade on motor behavior and dopamine release in the ventral pallidum. In a first experiment, rats were implanted with microdialysis probes in the ventral pallidum and were systemically injected or locally perfused via the microdialysis probe with dizocilpine (0.32 mg/kg, 10 and 100 microM, respectively). Effects on dopamine and on locomotion were simultaneously monitored. In a second experiment, ventral pallidum was lesioned by quinolinic acid and the effects of systemic dizocilpine (0.08 and 0.16 mg/kg) on locomotion and stereotyped sniffing behavior were determined. It was found that systemic and local dizocilpine administration increased dopamine release in the ventral pallidum to a similar extent whereas only systemic treatment was accompanied by locomotor stimulation. Lesion of the ventral pallidum did not affect locomotion and stereotyped sniffing behavior induced by systemic dizocilpine treatment. Thus, DA release in the ventral pallidum that is elevated by blockade of NMDA receptors is not relevant for activation of motor behavior.  相似文献   
8.
梅毒是由梅毒螺旋体进入循环系统进行血行播散导致的多系统损害,但目前其全身播散的具体机制尚未完全明确.基于国内外的研究进展,本文从梅毒螺旋体黏附与细胞外基质降解、细胞间连接和细胞骨架系统破坏、血管生成、炎症细胞浸润等多方面探讨梅毒螺旋体血行播散的机制,为进一步研究提供理论基础.  相似文献   
9.
目的 分别从梅毒螺旋体(Treponema pallidum,Tp)临床菌株和尖锐湿疣(cA)组织中扩增人乳头瘤病毒(HPV)6b型L1和TpN15基因,构建HPV6b L1-TpN15嵌合基因及其原核表达系统.方法 采用PCR分别从CA组织及Tp临床菌株中扩增HPV6b L1和TpN15基因片段,构建HPV6b L1-TpN15嵌合基因,将其克隆入原核表达载体pET32a(+)构建重组质粒pET32a(+)/HPV6b L1-TpN15,经测序鉴定后转化大肠杆菌BL21 (DE3),经异丙基硫代-β-D-半乳糖苷(IPTG)诱导后表达的融合蛋白用十二烷基磺酸钠(SDS)-聚丙烯酰胺凝胶电泳(PAGE)、蛋白质印迹法分析鉴定.结果 HPV6b L1-TpN15融合蛋白在原核表达系统中得到了较高表达.结论 原核表达的HPV6bL1-TpN15融合蛋白具较强的抗原性.  相似文献   
10.
为探讨海藻多糖抗氧化活性及抗衰老作用,体外测定昆布多糖,羊栖菜多糖,海蒿子多糖对羟基自由基,超氧自由基及其DPPH自由基的清除作用;采用秀丽隐杆线虫为研究模型,在培养基中添加不同浓度的海藻多糖,每日定时观察并记录线虫存活数,计算平均存活率。结果表明海藻多糖具有抗氧化能力,其中1.2mg/mL的昆布多糖羟基自由基清除能力最强,达到92.10%;海蒿子多糖DPPH自由基的清除能力最强,当浓度达到1.2mg/mL时,清除率为59.55%;1mg/mL海蒿子多糖超氧自由基的清除率达15.66%。秀丽隐杆线虫寿命实验表明,不同的海藻多糖均能延长线虫的寿命,且在实验浓度下,多糖浓度越高寿命延长越明显。研究结果表明所选海藻多糖具有显著的体外抗氧化活性,动物实验表明海藻多糖具有抗衰老作用,能显著延长线虫寿命。该结果为海藻多糖应用于医药、保健品领域的开发提供了一定的实验基础。  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