全文获取类型
收费全文 | 228篇 |
免费 | 34篇 |
国内免费 | 52篇 |
专业分类
314篇 |
出版年
2024年 | 2篇 |
2023年 | 7篇 |
2022年 | 6篇 |
2021年 | 8篇 |
2020年 | 15篇 |
2019年 | 18篇 |
2018年 | 10篇 |
2017年 | 18篇 |
2016年 | 11篇 |
2015年 | 11篇 |
2014年 | 10篇 |
2013年 | 16篇 |
2012年 | 15篇 |
2011年 | 19篇 |
2010年 | 13篇 |
2009年 | 11篇 |
2008年 | 11篇 |
2007年 | 25篇 |
2006年 | 20篇 |
2005年 | 15篇 |
2004年 | 10篇 |
2003年 | 6篇 |
2002年 | 7篇 |
2001年 | 8篇 |
2000年 | 7篇 |
1999年 | 4篇 |
1998年 | 3篇 |
1996年 | 1篇 |
1995年 | 3篇 |
1994年 | 1篇 |
1992年 | 2篇 |
1991年 | 1篇 |
排序方式: 共有314条查询结果,搜索用时 15 毫秒
81.
长寿不仅取决于良好的生活习惯,还取决于基因的作用。美国波士顿“衰老研究所”的科学家们,最近通过对137组长寿的兄弟姐妹(共300余人,年龄为91~108岁)的脱氧核糖核酸进行详尽比较和分析,发现长寿者身上果然具有与众不同的所谓“长寿基因”,而且还找到了这些“长寿基因”的大概位置。主持此项研究的波尔斯医生指出,百岁老人十分罕见,在人口中仅占万分之一,但当你在一个家族中发现竟有好几个百岁老人时,你就能相信:长寿不仅取决于培养良好的生活习惯,而且更取决于基因的作用。这就是说,“遗传优势”在决定一个人能活得较长时,起的往往是“主… 相似文献
82.
孟子继承发挥孔子仁学德治思想,提出以民为本的仁政学说,经剔除其封建糟粕,具超时代超阶级的积极意义.孟子仁政说中保民而王、亲亲仁民、与民同乐及制民之产以安民富民的思想,其积极意义、历史贡献须充分肯定,它对我们今天加强党风政风建设,促进加强社会主义政治文明精神文明建设,促进全面建设和谐小康社会,有现实意义,须大力弘扬. 相似文献
83.
荀子"化性起伪"."隆礼重法"的政治思想是建立在他的性恶的人性论基石上的。以礼为本、德法并举、德主刑辅、礼义教化与法律强制相辅相成,是他政治思想的核心内容,也是其对儒家德治思想的创新发展。剔除其封建糟粕,它对我们今天建设和谐小康社会仍可提供有益的启示。 相似文献
84.
A widely adopted approach in cognitive psychology research is to analyze changes in the response time to a stimulus onset
in order to infer information about the cognitive functioning of a subject being tested. But current techniques have inherent
variations in the timing between stimulus activation and stimulus display of up to tens of milliseconds, thereby introducing
significant errors when response time or the latency of neural responses is measured. This article presents a novel yet easy-to-implement
solution for improving resolution in the synchronizing of stimulus activation and stimulus display. Unlike traditional methods
in which the stimulus onset is set as the time at which the routine for displaying the stimulus is called, this approach uses
DirectX to monitor the scan line of CRTs and sets the stimulus onset to the time at which the scan line arrives at the position
where the stimulus is to be drawn. This approach removes the uncertainty involved in having a time delay between the activation
of the display routine and the actual time at which the display occurs, improving the accuracy of response time and latency
period measurements to within 200 μsec. With a specially developed driver, this solution can generate a trigger signal synchronized
precisely with the stimulus onset in all popular Windows systems (including Windows 2000/XP). 相似文献
85.
This study examined the interactive effects of job demands, control, and individual characteristics on upper respiratory illnesses and immune function. Having high job control appeared to lessen the linkage between job demands and poor health among individuals with high self-efficacy and those who perceived that they were not often responsible for negative job outcomes. Conversely, having high job control exacerbated the association between job demands and poor health among inefficacious individuals. Implications for promoting more healthful work environments and facilitating employee coping are discussed. 相似文献
86.
The effectiveness of tetraethylammonium (TEA) and high-frequency stimulation (HFS) in inducing long-term synaptic modification is compared in CA1 and dentate gyrus (DG) in vitro. High-frequency stimulation induces long-term potentiation (LTP) at synapses of both perforant path-DG granule cell and Schaffer collateral-CA1 pyramidal cell pathways. By contrast, TEA (25 mM) induces long-term depression in DG while inducing LTP in CA1. The mechanisms underlying the differential effect of TEA in CA1 and DG were investigated. It was observed that T-type voltage-dependent calcium channel (VDCC) blocker, Ni2+ (50 microM), partially blocked TEA-induced LTP in CA1. A complete blockade of the TEA-induced LTP occurred when Ni2+ was applied together with the NMDA receptor antagonist, D-APV. The L-type VDCC blocker, nifidipine (20 microM), had no effect on CA1 TEA-induced LTP. In DG of the same slice, TEA actually induced long-term depression (LTD) instead of LTP, an effect that was blocked by D-APV. Neither T-type nor L-type VDCC blockade could prevent this LTD. When the calcium concentration in the perfusion medium was increased, TEA induced a weak LTP in DG that was blocked by Ni2+. During exposure to TEA, the magnitude of field EPSPs was increased in both CA1 and DG, but the increase was substantially greater in CA1. Tetraethylammonium application also was associated with a large, late EPSP component in CA1 that persisted even after severing the connections between CA3 and CA1. All of the TEA effects in CA1, however, were dramatically reduced by Ni2+. The results of this study indicate that TEA indirectly acts via both T-type VDCCs and NMDA receptors in CA1 and, as a consequence, induces LTP. By contrast, TEA indirectly acts via only NMDA receptors in DG and results in LTD. The results raise the possibility of a major synaptic difference in the density and/or distribution of T-type VDCCs and NMDA receptors in CA1 and DG of the rat hippocampus. 相似文献
87.
Dong Song Xiaping Xie Zhuo Wang Theodore W. Berger 《Neurobiology of learning and memory》2001,76(3):375
The effectiveness of tetraethylammonium (TEA) and high-frequency stimulation (HFS) in inducing long-term synaptic modification is compared in CA1 and dentate gyrus (DG) in vitro. High-frequency stimulation induces long-term potentiation (LTP) at synapses of both perforant path-DG granule cell and Schaffer collateral-CA1 pyramidal cell pathways. By contrast, TEA (25 mM) induces long-term depression in DG while inducing LTP in CA1. The mechanisms underlying the differential effect of TEA in CA1 and DG were investigated. It was observed that T-type voltage-dependent calcium channel (VDCC) blocker, Ni2+ (50 μM), partially blocked TEA-induced LTP in CA1. A complete blockade of the TEA-induced LTP occurred when Ni2+ was applied together with the NMDA receptor antagonist, D-APV. The L-type VDCC blocker, nifidipine (20 μM), had no effect on CA1 TEA-induced LTP. In DG of the same slice, TEA actually induced long-term depression (LTD) instead of LTP, an effect that was blocked by D-APV. Neither T-type nor L-type VDCC blockade could prevent this LTD. When the calcium concentration in the perfusion medium was increased, TEA induced a weak LTP in DG that was blocked by Ni2+. During exposure to TEA, the magnitude of field EPSPs was increased in both CA1 and DG, but the increase was substantially greater in CA1. Tetraethylammonium application also was associated with a large, late EPSP component in CA1 that persisted even after severing the connections between CA3 and CA1. All of the TEA effects in CA1, however, were dramatically reduced by Ni2+. The results of this study indicate that TEA indirectly acts via both T-type VDCCs and NMDA receptors in CA1 and, as a consequence, induces LTP. By contrast, TEA indirectly acts via only NMDA receptors in DG and results in LTD. The results raise the possibility of a major synaptic difference in the density and/or distribution of T-type VDCCs and NMDA receptors in CA1 and DG of the rat hippocampus. 相似文献
88.
风险情景中的机会和威胁认知 总被引:8,自引:0,他引:8
随着近年来社会经济的高速发展 ,人们面临着越来越多的风险问题。该研究的目的在于深入分析个体成就动机、风险情景中的行为反应方式以及机会 -威胁认知三者之间的关系。研究采用问卷设计 ,由成就动机量表、抽彩游戏和机会 -威胁问卷三部分组成。被试来自北京和重庆地区的三所高校 (N =2 6 2 )。结果发现 :(1)成就动机中的“回避失败”变量对个体在风险情景中的反应方式以及机会 -威胁认知有显著性的影响 (p <0 0 5 ) ;(2 )机会 -威胁认知水平不同的个体在风险情景中的反应方式有着显著性的差异 (p <0 0 1) ,机会认知与行为变量的相关达到了显著性水平 (p <0 0 5 ) ;(3)四组被试分别表现出高机会 -低威胁等 4种认知组合 ,因此机会与威胁认知可能存在于两维空间 相似文献
89.
工作家庭冲突对电讯人员工作倦怠和心理健康的影响 总被引:3,自引:0,他引:3
采用工作家庭冲突问卷、工作倦怠问卷(MBI-Gs)和一般健康状况问卷(GHQ-12)调查了某国营电讯公司526名员工。中介回归分析(Mediating Regressin Analysis)的结果显示,工作家庭冲突及其两个子成分(工作浸扰家庭和家庭浸扰工作)都对心理健康具有显著的负向影响;工作倦怠对工作家庭冲突影响心理健康具有完全中介作用;具体而言,工作浸扰家庭对心理健康的影响受情绪衰竭和玩世不恭的完全中介;家庭浸扰工作对心理健康的影响受工作倦怠所有三个子成分的完全中介。 相似文献
90.
目的:探讨体育专业大学生网络心理的特点。方法:采用自编大学生网络心理问卷,对某省236名体育专业大学生和331名非体育专业大学生的网络心理进行调查和比较。结果:(1)体育专业大学生网络喜好程度显著低于非体育专业大学生。(2)体育专业大学生对网络依恋程度低于非体育专业大学生。(3)体育专业大学生对网络人际交往依赖程度低于非体育专业大学生。(4)体育专业大学生在上网目的性上表现为"学习需要"等,非体育专业大学生上网是为了"寻求自信"等。 相似文献