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   936篇
  免费   169篇
  国内免费   366篇
  2023年   18篇
  2022年   29篇
  2021年   43篇
  2020年   63篇
  2019年   32篇
  2018年   55篇
  2017年   41篇
  2016年   49篇
  2015年   39篇
  2014年   60篇
  2013年   79篇
  2012年   91篇
  2011年   89篇
  2010年   91篇
  2009年   80篇
  2008年   79篇
  2007年   131篇
  2006年   98篇
  2005年   82篇
  2004年   48篇
  2003年   37篇
  2002年   33篇
  2001年   17篇
  2000年   17篇
  1999年   11篇
  1998年   4篇
  1997年   6篇
  1996年   8篇
  1995年   6篇
  1994年   6篇
  1993年   3篇
  1992年   2篇
  1991年   2篇
  1990年   4篇
  1989年   2篇
  1988年   2篇
  1987年   2篇
  1986年   1篇
  1985年   6篇
  1984年   3篇
  1981年   1篇
  1979年   1篇
排序方式: 共有1471条查询结果,搜索用时 15 毫秒
81.
首词和尾词频率对高熟悉度成语识别的影响   总被引:1,自引:1,他引:0  
采用词汇判定法,考察首词频率和尾词频率对高熟悉度四字成语识别的影响。实验结果表明:(1)对高熟悉度成语的识别规律与多层聚类表征模型的观点比较吻合;(2)构成成语的成份词对成语表征有竞争和干扰作用,高频率成份词相对于低频率成份词,对成语表征的竞争和干扰作用较大。  相似文献   
82.
Cellular precipitation (also known as discontinuous precipitation) has been observed at the grain boundaries of a newly developed nickel-based Inconel740H alloy designed for use at 700?°C in advanced ultrasupercritical coal-fired power plants. By means of element mapping and selected area diffraction, the cellular precipitates were identified as Cr-rich M23C6 carbides. The onset of cellular precipitation was found to follow a pucker mechanism in Inconel740H. The cellular precipitates at the grain boundaries, even at low volume fractions, were severely detrimental to the creep strength at 750?°C. The creep rupture life of Inconel740H containing cellular precipitates at grain boundaries was only one-tenth of that for the alloy without cellular precipitates. The reason for the drastically decreased creep rupture life is attributed to the poor resistance of cellular precipitates to crack propagation during creep.  相似文献   
83.
含有生物碱类、皂苷类、萜类、毒蛋白类、重金属类成分的中药易致急性肝损伤.中药对肝脏损伤的原因及机制较为复杂,可能与药物对肝脏的直接毒性或特异性体质有关.此外,中药炮制方法、给药途径、剂型、剂量、疗程及配伍不当也会引起药物性肝损伤.中药所致的药物性肝损伤的诊断主要依据用药史、发病的时间、过程和临床表现并排除其他因素.治疗可选用还原型谷胱甘肽、S-腺苷蛋氨酸、多烯磷脂酰胆碱、熊去氧胆酸、水飞蓟素等药物,重症可选择人工肝脏支持治疗.  相似文献   
84.
阿尔茨海默病(AD)是常见的中枢神经系统变性疾病,是痴呆最常见的病因,发病率高.病理特征为老年斑及神经元纤维缠结.AD的确诊有赖病理学,临床诊断极其耗时.由于尚无准确的早期诊断方法,常使AD患者错过早期治疗的时机,这成为制约有效防控AD的瓶颈问题.因此寻找高敏感性、特异性、无创性的生物学标志物对AD的早期诊断至关重要.本文仅将目前较为广泛研究的生物学标志物及其研究现状作一概述.分别对脑脊液、血液、尿液及唾液中的AD标志物作逐一介绍.  相似文献   
85.
医学教育是贯穿医疗职业生涯全过程的行为,是伴随医学进步和发展的重要工程.医学教育的质量直接影响医疗的质量和医学人才的素质,尤其是外科学领域,是以有创性的手段、方法治疗疾病.医生的职业素养、医疗水平均取决于医学教育的结果.医疗质量不能简单地用医生的学历衡量,学历教育是载体,其中应充实培养能力的教育项目、内容,以适应未来就职、就业的社会需求.医疗质量、医疗水平对医院而言是生命线,是生产力.同时,医生的教育及教育的质量是医疗质量的基础与保障.随着医学的飞速发展,医疗技术的日新月异,医学模式的改变,构建新的医疗环境下的医学教育体系,显得更为重要.  相似文献   
86.
总结术后早期炎性肠梗阻的临床治疗经验及防治措施.回顾性分析36例腹部手术后早期炎性肠梗阻患者临床治疗方法.33例经非手术治疗治愈,平均治愈时间(15.5±9.5)d,1例自动出院,2例转往上级医院进一步治疗.腹部手术后早期炎性肠梗阻应以保守治疗为主,有效的治疗包括禁食、胃肠减压、全肠外营养支持、糖皮质激素和生长抑素的应用.炎性肠梗阻选择非手术治疗,既保证了治疗的有效性,同时也能够让患者接受.  相似文献   
87.
Sketching is widely used in design to generate creative ideas. Design studies present stimuli during sketching to enhance creativity. This study examines the effect of stimuli presented during different sketching states, especially of those presented during the stuck period. It conducted a sketching experiment that enrolled 41 students with an average of 5.7 years’ practice in industrial design. The sketching with stimuli presented at regular intervals, those with stimuli presented during the stuck period, and those without stimulus were compared. Eye movements during the sketching processes were recorded. The attention to stimuli, and the direct applications of stimuli to design ideas, and the idea connection and idea differentiation were analyzed. Participants sketching with stimuli presented during the stuck period had a higher sketching quality, compared with those in other experimental conditions. They fixated longer on stimuli, built more links among related ideas, and had a more differentiated and balanced exploration. This study then proposed the mechanisms of stimuli processing. The stimuli presented at regular intervals were stored and acted as additional memory. The stimuli presented during the stuck period were dissected and acted as supporter, inducing a more creative sketching.  相似文献   
88.
Past research has consistently found that people are likely to do worse on high‐level cognitive tasks after exerting self‐control on previous actions. However, little has been unraveled about to what extent ego depletion affects subsequent prospective memory. Drawing upon the self‐control strength model and the relationship between self‐control resources and executive control, this study proposes that the initial actions of self‐control may undermine subsequent event‐based prospective memory (EBPM). Ego depletion was manipulated through watching a video requiring visual attention (Experiment 1) or completing an incongruent Stroop task (Experiment 2). Participants were then tested on EBPM embedded in an ongoing task. As predicted, the results showed that after ruling out possible intervening variables (e.g. mood, focal and nonfocal cues, and characteristics of ongoing task and ego depletion task), participants in the high‐depletion condition performed significantly worse on EBPM than those in the low‐depletion condition. The results suggested that the effect of ego depletion on EBPM was mainly due to an impaired prospective component rather than to a retrospective component.  相似文献   
89.
This paper explores trust of mobile applications based on users' behaviors. It proposes a trust behavior construct through principal component analysis, reliability analysis, and confirmatory factor analysis based on the data collected from a questionnaire survey with more than 1,500 participants. It is indicated that a user's trust behavior is composed of three principal constructs: using behavior, reflection behavior, and correlation behavior. They are further delineated into 12 measurable sub‐constructs and relate to a number of external factors. The data analysis showed that the questionnaire has positive psychometric properties with respect to construct validity and reliability. We also discuss the practical significance and limitations of our work toward usable trust management.  相似文献   
90.
ABSTRACT

This research was designed to test the hypothesis that motor practice can enhance the capabilities of motor control in healthy controls (NC) and patients with a diagnosis of probable Alzheimer's disease (AD) and mild cognitive impairment (MCI), and consequently results in better motor performance. Approximately half of the subjects in the NC (n = 31), AD (n = 28), and MCI (n = 29) either received or did not receive practice on a task of fast and accurate arm movement with a digitizer. Changes in movement time (MT), movement smoothness (jerk), and percentage of primary submovement (PPS) were recorded and compared among the three groups across six blocks of trials (baseline and five training sessions). For all subjects, practice improved motor functions as reflected by faster and smoother motor execution, as well as a greater proportion of programming control. Compared to unaffected matched controls, AD and MCI subjects exhibited a greater reduction in movement jerk due to practice. Movement time and PPS data revealed that motor practice appeared to reduce the use of “on-line” correction adopted by the AD or MCI patients while performing the aiming movements. Evidently, their arm movements were quicker, smoother, and temporally more consistent than their untrained peers. The findings of this study shed light on how MCI and AD may affect motor control mechanisms, and suggest possible therapeutic interventions aimed at improving motor functioning in these impaired individuals.  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