全文获取类型
收费全文 | 836篇 |
免费 | 147篇 |
国内免费 | 337篇 |
专业分类
1320篇 |
出版年
2024年 | 1篇 |
2023年 | 24篇 |
2022年 | 25篇 |
2021年 | 39篇 |
2020年 | 62篇 |
2019年 | 27篇 |
2018年 | 48篇 |
2017年 | 36篇 |
2016年 | 45篇 |
2015年 | 36篇 |
2014年 | 55篇 |
2013年 | 67篇 |
2012年 | 88篇 |
2011年 | 79篇 |
2010年 | 79篇 |
2009年 | 69篇 |
2008年 | 66篇 |
2007年 | 114篇 |
2006年 | 90篇 |
2005年 | 77篇 |
2004年 | 40篇 |
2003年 | 32篇 |
2002年 | 26篇 |
2001年 | 16篇 |
2000年 | 17篇 |
1999年 | 11篇 |
1998年 | 4篇 |
1997年 | 5篇 |
1996年 | 8篇 |
1995年 | 5篇 |
1994年 | 3篇 |
1993年 | 3篇 |
1992年 | 1篇 |
1991年 | 2篇 |
1990年 | 4篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1985年 | 6篇 |
1984年 | 3篇 |
1981年 | 1篇 |
排序方式: 共有1320条查询结果,搜索用时 15 毫秒
81.
Yan Chong Zhengdong Liu Andy Godfrey Wei Liu Yuqing Weng 《Philosophical Magazine Letters》2013,93(12):688-696
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
82.
李岩 《医学与哲学(人文社会医学版)》2013,(10):21-22,40
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
83.
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
84.
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
85.
Jian‐Bin Li Yan‐Gang Nie Min‐Xia Zeng Meghan Huntoon Jessi L. Smith 《International journal of psychology》2013,48(6):1303-1312
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
86.
Zheng Yan Yan Dong Valtteri Niemi Guoliang Yu 《Journal of applied social psychology》2013,43(3):638-659
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
87.
Dmitry Leykin Mooli Lahad Odeya Cohen Avishay Goldberg Limor Aharonson-Daniel 《American journal of community psychology》2013,52(3-4):313-323
Community resilience is used to describe a community’s ability to deal with crises or disruptions. The Conjoint Community Resiliency Assessment Measure (CCRAM) was developed in order to attain an integrated, multidimensional instrument for the measurement of community resiliency. The tool was developed using an inductive, exploratory, sequential mixed methods design. The objective of the present study was to portray and evaluate the CCRAM’s psychometric features. A large community sample (N = 1,052) were assessed by the CCRAM tool, and the data was subjected to exploratory and confirmatory factor analysis. A Five factor model (21 items) was obtained, explaining 67.67 % of the variance. This scale was later reduced to 10-item brief instrument. Both scales showed good internal consistency coefficients (α = .92 and α = .85 respectively), and acceptable fit indices to the data. Seven additional items correspond to information requested by leaders, forming the CCRAM28. The CCRAM has been shown to be an acceptable practical tool for assessing community resilience. Both internal and external validity have been demonstrated, as all factors obtained in the factor analytical process, were tightly linked to previous literature on community resilience. The CCRAM facilitates the estimation of an overall community resiliency score but furthermore, it detects the strength of five important constructs of community function following disaster: Leadership, Collective Efficacy, Preparedness, Place Attachment and Social Trust. Consequently, the CCRAM can serve as an aid for community leaders to assess, monitor, and focus actions to enhance and restore community resilience for crisis situations. 相似文献
88.
Jin H. Yan Malcolm B. Dick 《Neuropsychology, development, and cognition. Section B, Aging, neuropsychology and cognition》2013,20(3-4):385-410
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
89.
本工作对两例先天性无痛症患者对于致痛性强刺激的知觉和反应进行了研究(例1女,10岁,例2男,13岁)。对照组为20例正常儿童,性别和年龄均与患儿相匹配。 结果:1),生活中痛:两例患儿均无(包括痛感觉和痛反应)。2)实验性痛:①痛感觉:两例患儿均无;②“痛”反应:例1有“痛”反应(脉搏和呼吸的变化以及行为反应明显,大致与正常儿童相似)。例2无“痛”反应(脉搏和呼吸的变化轻微,无行为反应,与正常儿童不同)。 由结果看来,先天性无痛症患者似乎可分为两种类型:不完全型(如同例1)和完全型(如同例2)。存在有“痛”反应而无痛感觉的无痛症患者。 本工作结果从另一侧面为痛的两成分学说提供了依据。 相似文献
90.
Pui–Yan Lam 《Journal for the scientific study of religion》2002,41(3):405-422
This study investigates the relationship between different dimensions of religiosity and voluntary association participation using data from Queen'sUniversity's 1996 "God and Society in North America" survey. I look at the participatory, devotional, affiliative, and theological dimensions of religiosity and examine how they affect voluntary association participation at three different levels: membership, volunteering, and serving on a committee. The results show that all four religious dimensions have considerable, but distinctive, influences on secular voluntary association participation. 相似文献