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   2145篇
  免费   149篇
  国内免费   2篇
  2023年   19篇
  2022年   22篇
  2021年   42篇
  2020年   75篇
  2019年   50篇
  2018年   100篇
  2017年   97篇
  2016年   104篇
  2015年   93篇
  2014年   70篇
  2013年   307篇
  2012年   103篇
  2011年   129篇
  2010年   85篇
  2009年   84篇
  2008年   125篇
  2007年   93篇
  2006年   71篇
  2005年   80篇
  2004年   46篇
  2003年   62篇
  2002年   58篇
  2001年   50篇
  2000年   38篇
  1999年   23篇
  1998年   21篇
  1997年   18篇
  1996年   20篇
  1995年   10篇
  1994年   13篇
  1993年   9篇
  1992年   5篇
  1991年   11篇
  1990年   13篇
  1989年   8篇
  1988年   6篇
  1987年   5篇
  1986年   6篇
  1985年   5篇
  1984年   6篇
  1983年   7篇
  1982年   11篇
  1981年   7篇
  1980年   6篇
  1978年   7篇
  1975年   11篇
  1973年   5篇
  1971年   6篇
  1970年   5篇
  1966年   4篇
排序方式: 共有2296条查询结果,搜索用时 15 毫秒
951.
Since Berger’s discovery of the electroencephalogram (EEG), its analysis has been generally restricted to the visual range (upmost 100Hz) and has ignored higher frequency components. One reason should be that there are no reliable methods to distinguish the brain potentials from muscle activity. We have introduced fluctuation analysis, which is popular method especially in the field of basic physiology to clinical electrophysiology. In our previous study, it was declared that power spectral density (PSD) of human high frequency EEG was composed of double Lorentzians and vanished into white level within 1kHz. Then the purpose of this study is to elucidate the “Automated Fluctuation Analysis,” which enables us to evaluate these higher frequency components and its physiological meaning especially focused on conscious level from wakefulness to sleep stage 1. Seventy-four scalp recording EEGs in twenty normal subjects were studied. In short, “Automated Fluctuation Analysis” is made of three steps: amplification of EEG signal, A/D conversion and Fast Fourier Transform by signal processor and extraction of Lorentzian parameters. PSD of high frequency EEG was displayed on log-log graph and the algorithm fit to the following Lorentzian formula were mathematically based on Brown & Dennis. S(f)=S1/ [1+(f/fc1)2] + S2/ [1+(f/fc2)2], where S(f) is PSD (μ V2/Hz) at each frequency (f;Hz), S1 and S2 are the plateau level or zero-frequency power of the initial and second Lorentz, and fc1 and fc2 are the corner or half-power frequency of the initial and second Lorentz, respectively. As results, during wakefulness the PSD of high frequency EEG activity was composed of double Lorentzian fluctuations and the power distribution of S1 value in topographical display was frontal dominant. This pattern of S1 value disappeared and S2 value became lower during sleepiness and the second Lorentz disappeared during sleep.  相似文献   
952.
Should we change the human genome? The most general arguments against changing the human genome are here in focus. Distinctions are made between positive and negative gene therapy, between germ-line and somatic therapy, and between therapy where the intention is to benefit a particular individual (a future child) and where the intention is to benefit the human gene-pool. Some standard arguments against gene-therapy are dismissed. Negative somatic therapy is not controversial. Even negative, germ-line therapy is endorsed, if the intention is to cure a certain individual (a future child). In rare cases, positive therapy on somatic cells may be warranted. Germ-line therapy may become a valuable method of preventing harm, through ‘genetic vaccination’. If safe methods evolve, it is harmless (though vain), to try to achieve more ambitious goals. Prospective parents should not be prevented from exercising this harmless kind of parental authority. The paper concludes: Thereis a moral limit to how much we ought to manipulate the human genome, however. We ought not to jeopardize the continued existence of mankind. We ought not to develop methods of germ-line therapy intended in a radical manner to improve human nature, and we ought to leave to prospective parents to decide in individual cases what kind of intervention shall take place.  相似文献   
953.
The phonemic errors of three Finnish Broca's aphasics were analyzed according to various phonological features, frequency of segments, syllable, word, and stress positions, as well as for the phonotactic structure of the uncanonical products. It was found, e.g., that the distance between the syntagmatic error and its source could not be satisfactorily counted by phonemes, since the syllable had to be taken into account also in pathological Finnish. As regards the paradigmatic dimension of the errors, the number of incorrect features is even here in reverse relation to the frequency of the erroneous phonemes. Moreover, it was found that pure quantity errors and vowel harmony deviations are infrequent in the speech of Finnish Broca's aphasics.  相似文献   
954.
955.
The purpose of this study is to examine the reported level of self-disclosure in online communication and understand the relationship between perceived interpersonal competence and self-disclosure in an online context, taking into account the moderating role of shyness. The study sample consists of university students (N = 585). Hierarchical multiple linear regression analyses revealed that, controlling for participants' online media use, shyness moderated the relationship between online self-disclosure and perceived interpersonal competence. Moderation results showed that the relationship between online self-disclosure and perceived interpersonal competence was weaker for individuals with higher levels of shyness, and stronger for those with moderate or low scores on the shyness measure. The study's implications and contributions to the existing literature are discussed.  相似文献   
956.
957.
958.
959.
G Vikár 《Psyche》1977,31(12):1133-1143
  相似文献   
960.
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