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   488篇
  免费   24篇
  国内免费   1篇
儿科学   3篇
妇产科学   3篇
基础医学   119篇
口腔科学   3篇
临床医学   61篇
内科学   33篇
皮肤病学   4篇
神经病学   114篇
特种医学   20篇
外科学   23篇
综合类   5篇
预防医学   104篇
眼科学   6篇
药学   14篇
肿瘤学   1篇
  2023年   6篇
  2021年   5篇
  2019年   4篇
  2018年   3篇
  2017年   5篇
  2015年   4篇
  2014年   8篇
  2013年   10篇
  2012年   13篇
  2011年   18篇
  2010年   10篇
  2009年   8篇
  2008年   23篇
  2007年   27篇
  2006年   14篇
  2005年   23篇
  2004年   25篇
  2003年   26篇
  2002年   12篇
  2001年   11篇
  2000年   16篇
  1999年   12篇
  1998年   11篇
  1997年   9篇
  1996年   15篇
  1995年   8篇
  1994年   10篇
  1993年   12篇
  1992年   9篇
  1991年   10篇
  1990年   12篇
  1989年   11篇
  1988年   7篇
  1987年   4篇
  1986年   7篇
  1985年   11篇
  1984年   10篇
  1983年   8篇
  1982年   8篇
  1981年   3篇
  1980年   4篇
  1979年   7篇
  1978年   4篇
  1977年   5篇
  1976年   9篇
  1975年   4篇
  1974年   6篇
  1973年   5篇
  1971年   6篇
  1970年   4篇
排序方式: 共有513条查询结果,搜索用时 15 毫秒
1.
Understanding the mechanisms of food intake and obesity   总被引:2,自引:1,他引:1  
  相似文献   
2.
1. Since plasma renin activity is increased in cyclosporin A (CsA)-induced hypertension in the rat, the role of the vascular renin-angiotensin system (RAS) in CsA-induced hypertension was investigated in rat mesenteric resistance vessels. 2. Female Wistar rats received CsA (10 mg/kg per day, s.c.) or vehicle for 30 days. CsA treatment increased tail-cuff systolic blood pressure (CsA treated 135 ± 3 mmHg vs control 125 ± 1 mmHg, P<0.0001). 3. Mesenteric resistance arteries (200–300 μm) were isolated and mounted in a microvessel myograph. Concentration-response curves to tetradecapeptide renin substrate (10-11-10?6 mol/L), angiotensin I (10-l1-10?6 mol/L) and angiotensin II (10-12-10?6 mol/L) showed no differences between CsA-treated and control groups. 4. Mesenteric vascular angiotensin-converting enzyme (ACE) characteristics were determined by radioligand binding. There were no differences in the content or affinity of ACE between CsA-treated and control rats. 5. These results suggest that the mesenteric vascular RAS does not play a major role in CsA-induced hypertension in the rat.  相似文献   
3.
M J Tovee  E T Rolls 《Neuroreport》1992,3(4):369-372
It has been suggested in studies in the visual system of anaesthetized cats that oscillatory activity with a frequency of 40-60 Hz occurs during the presentation of moving visual stimuli and reflects a synchronization process between neurons that could implement the binding together of related neurons into different sets. We found no evidence for such oscillations in the inferior temporal visual cortex and related areas of awake macaques fixating effective static visual stimuli, which for the neurons analysed were faces. We put forward the possibility that temporal synchronization between neurons to implement binding may not be generally used in the visual system as a solution to the binding problem, at least when static objects are being processed and recognised in higher parts of the visual system.  相似文献   
4.
An Australian school of nursing's attempt to introduce an evaluation process required by management for clinical educators involved in undergraduate preregistration education is discussed Reliance on student feedback and clinical agencies' perceptions of the quality of teaching were seen as inadequate mechanisms for evaluation The evaluation process adopted incorporated observation of the educators together with self-reflection on their performance We conclude that post-briefings were poorly used and generally not reflective Educators relied heavily on their clinical skills and used a limited range of teaching strategies Whilst evaluation of clinical educators was time consuming and therefore costly, it is argued that it is essential to the integrity of the course The evaluation process has provided direction for support and development of clinical educators within the context of the curriculum  相似文献   
5.
6.
A key problem in reinforcement learning is how an animal is able to learn a sequence of movements when the reward signal only occurs at the end of the sequence. We describe how a hierarchical dynamical model of motor function is able to solve the problem of delayed reward in learning movement sequences using associative (Hebbian) learning. At the lowest level, the motor system encodes simple movements or primitives, while at higher levels the system encodes sequences of primitives. During training, the network is able to learn a high level motor program composed of a specific temporal sequence of motor primitives. The network is able to achieve this despite the fact that the reward signal, which indicates whether or not the desired motor program has been performed correctly, is received only at the end of each trial during learning. Use of a continuous attractor network in the architecture enables the network to generate the motor outputs required to produce the continuous movements necessary to implement the motor sequence.  相似文献   
7.
Body fluid changes, thirst and drinking in man during free access to water   总被引:2,自引:0,他引:2  
To investigate whether human thirst and drinking during ad lib access to water occur in response to body fluid deficits, we obtained blood samples and visual analog scale thirst ratings from five healthy, volunteer, young men at hourly intervals and when they were thirsty during a normal working day. Although there were significant increases in ratings of thirst, pleasantness of drinking water, mouth dryness and unpleasantness of the taste in the mouth when subjects were thirsty enough to drink compared with intervening intervals, there were no concomitant changes in body fluid variables (microhematocrit, plasma osmolality and plasma sodium, potassium, protein and angiotensin II concentrations). Subjects drank mainly in association with eating and were not overhydrated as indicated by constantly hypertonic urine and significant tubular reabsorption of free water over the experimental period. The results indicate that during free access to water humans become thirsty and drink before body fluid deficits develop, perhaps in response to subtle oropharyngeal cues, and so provide evidence for anticipatory thirst and drinking in man.  相似文献   
8.
个体化下肢小腿假肢接受腔设计的生物力学评价技术研究   总被引:3,自引:0,他引:3  
作为传递体重、固定假肢的部件 ,接受腔对于小腿假肢使用的舒适性和方便程度有决定性的作用。本研究建立了基于有限元应力分析的小腿假肢生物力学评价技术平台 ,实现了小腿残端 /接受腔 3D几何建模与信息交互、三维有限元自动建模及应力分析。 3D模型与信息交互的实现基于得到广泛支持的OpenGL技术 ,有限元模型的构建采用了专门针对小腿残端 /接受腔结构特点的自动建模方法 ,通过构建档案数据库系统作为整个系统的操作平台。该技术平台可与现有的CAD/CAM系统相结合 ,为接受腔的个体化设计提供生物力学定量化依据。其临床应用将改善传统的设计流程 ,提高设计效率。同时 ,它也是未来构建接受腔设计专家 /智能系统的基础。  相似文献   
9.
碱离子水饮用后血小板聚集率的的变化(附30例报告)   总被引:1,自引:0,他引:1  
目的:报告30例饮用豪斯牌碱离子水前、后血小板聚集率的变化。方法:饮用碱离子水前、后(2~3月,>3~6月)作比浊法血小板聚集试验,以1分钟、5分钟及5分钟内最大聚集率(Max%)为指标,同时检测部分血粘度指标及凝血因子,并用自动生化仪检测血糖、血脂、主要电解质及部分肝、肾功能。结果:饮碱离子水后,血小板聚集率明显下降,而以疾病组(Max>80%)下降尤为明显,P均<0.001。饮碱离子水后血小板聚集率的下降,部分可能与损伤的血管内皮得到修复有关。主要电解质及部分肝、肾功能无明显异常改变。结论:由于心、脑血管血栓性疾病患者血小板聚集率多明显升高,饮碱离子水后血小板聚集率明显下降,且长期饮用对主要电解质及部分肝、肾功能无明显异常改变,作者认为碱离子水使用方例、安全、有效、价廉,因而对心、脑血管血栓性疾病防治方面可能是一种积极的辅助方法,值得临床进一步探索。  相似文献   
10.
Although there has been much investigation of brain pathways involved in pain, little is known about the brain mechanisms involved in processing somatosensory stimuli which feel pleasant. Employing fMRI it was shown that pleasant touch to the hand with velvet produced stronger activation of the orbitofrontal cortex than affectively neutral touch of the hand with wood. In contrast, the affectively neutral but more intense touch produced more activation of the primary somatosensory cortex than the pleasant stimulus. This indicates that part of the orbitofrontal cortex is concerned with representing the positively affective aspects of somatosensory stimuli, and in further experiments it was shown that this orbitofrontal area is different from that activated by taste and smell. The finding that three different primary or unlearned types of reinforcer (touch, taste, and smell) are represented in the orbitofrontal cortex helps to provide a firm foundation for understanding the neural basis of emotions, which can be understood in terms of states elicited by stimuli which are rewarding or punishing.  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