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   16873篇
  免费   809篇
  国内免费   15篇
  2021年   132篇
  2020年   225篇
  2019年   241篇
  2018年   356篇
  2017年   359篇
  2016年   366篇
  2015年   281篇
  2014年   308篇
  2013年   1318篇
  2012年   569篇
  2011年   644篇
  2010年   371篇
  2009年   349篇
  2008年   472篇
  2007年   451篇
  2006年   393篇
  2005年   335篇
  2004年   339篇
  2003年   318篇
  2002年   323篇
  2001年   700篇
  2000年   699篇
  1999年   461篇
  1998年   180篇
  1997年   173篇
  1996年   138篇
  1995年   135篇
  1993年   138篇
  1992年   360篇
  1991年   321篇
  1990年   345篇
  1989年   334篇
  1988年   317篇
  1987年   288篇
  1986年   310篇
  1985年   298篇
  1984年   235篇
  1983年   200篇
  1979年   190篇
  1978年   161篇
  1975年   187篇
  1974年   241篇
  1973年   197篇
  1972年   203篇
  1971年   167篇
  1970年   149篇
  1969年   198篇
  1968年   202篇
  1967年   161篇
  1966年   182篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
341.
Dating experiences, especially the type or stage of dating, have consistently been found to be related to premarital sexual behavior. Findings regarding the age at 1st date and sexual behavior have been less consistent. This paper examined the age at which dating began and the type of dating relationship as correlates of premarital sexual attitudes and behavior among mid-teen adolescents. The analyses were based on a sample of high school students (n=836), most of whom were between the ages of 15 and 18 when the surveys were conducted. Early dating, especially early steady dating, was related to permissive attitudes and to premarital sexual experience among both males and females. The relationship between early dating and intercourse experience was particulary strong among Mormons, a religious group which has institutionalized age 16 as the legitimate age to begin dating.  相似文献   
342.
343.
Three experiments with rats (Rattus norvegicus) were conducted to examine the roles of the male's penile spines and penile cups (flaring of the distal glans) in the induction of luteal activity in the female, and in the removal of copulatory plugs from the vaginal tract. The results of Experiment 1 revealed no role for the cup in luteal induction but did suggest that elements of the ejaculatory reflex apart from cup formation contribute to the elicitation of this neuroendocrine response. The origin of this stimulatory effect was not directly determined, but indirect evidence suggested a role for penile spines. In Experiments 2 and 3, features of the glans penis that might help effect plug removal were investigated, and the experiments demonstrated that penile spines, perhaps in conjunction with penile cups, contribute to the extraction of plugs from the vagina.  相似文献   
344.
Since the 1970s, investigative profilers at the FBI's Behavioral Science Unit (now part of the National Center for the Analysis of Violent Crime) have been assisting local, state, and federal agencies in narrowing investigations by providing criminal personality profiles. An attempt is now being made to describe this criminal-profile-generating process. A series of five overlapping stages lead to the sixth stage, or the goal of apprehension of the offender: (1) profiling inputs, (2) decision-process models, (3) crime assessment, (4) the criminal profile, (5) investigation, and (6) apprehension. Two key feedback filters in the process are: (a) achieving congruence with the evidence, with decision models, and with investigation recommendations, and (b) the addition of new evidence.  相似文献   
345.
Adaptation and reaction-time techniques were used to examine the role of different spatial-frequency channels in the perception of local and global structure. Subjects were shown figures consisting of a large C composed of smaller Cs and asked to identify the orientation of either the global C or its local elements. Prior to performing the task subjects were adapted to different spatial frequencies and the effect on subsequent performance was assessed. Two main results were found. First, the adapting frequency that most affected the global task was often lower than that most affecting the local task, suggesting that high and low frequencies independently code the structure of an image. Second, reaction time to global figures was often faster than to local figures at all levels of detectability, again suggesting a role of low-frequency channels in global processing.  相似文献   
346.
E K Warrington  M James 《Perception》1986,15(3):355-366
An investigation is reported of the ability of normal subjects and patients with right-hemisphere lesions to identify 3-D shadow images of common objects from different viewpoints. Object recognition thresholds were measured in terms of angle of rotation (through the horizontal or vertical axis) required for correct identification. Effects of axial rotation were very variable and no evidence was found of a typical recognition threshold function relating angle of view to object identification. Although the right-hemisphere-lesion group was consistently and significantly worse than the control group, no qualitative differences between the groups were observed. The findings are discussed in relation to Marr's theory that the geometry of a 3-D shape is derived from axial information, and it is argued that the data reported are more consistent with a distinctive-features model of object recognition.  相似文献   
347.
Summary Subjects were shown eight-letter pseudowords tachistoscopically and were asked to report as many letters as possible. The pseudowords, examples of either first- or fourth-order approximation to English, were printed in normal or reversed spelling and were presented in either normal of mirror-imaged letters. Finally subjects were either free to report in any order they wished, or they were instructed to report from left to right or from right to left. With normal letters, the familiarity effect was controlled by the spelling direction, not by the direction of report or the match between direction of report and spelling direction. With mirrored letters, however, order of approximation to English had no effect. The results contradict two existing theories: Mewhort's theory claims that the familiarity of fourth-order materials aids processing at a postcategorical level; it has trouble explaining why the familiarity effect disappeared with mirrored letters and normal spelling. Wolff's theory claims that familiarity aids processing at the feature level; it has trouble explaining why the familiarity effect disappeared with mirrored letters and reversed spelling.  相似文献   
348.
349.
Modifications and corrections to Rayfield’s (1982) assembly language routines for data acquisition and experimental control using the Apple II computer are described. The modified routines, together with an optoisolated hardware interface, provide a reliable, accurate, and easy to use microcomputer system for experimental control and data acquisition.  相似文献   
350.
Forty normotensive subjects participated on a voluntary basis in a study designed to compare the effect of suggestions on blood pressure (BP). Two experimental groups received suggestions presumed to be specific in lowering or raising BP after simple relaxation (relaxation group) or hypnotic induction (hypnotic group). A control group was used to record the BP changes over time. The time variable was significant for both systolic (SBP) and diastolic blood pressure (DBP). Induction procedures (hypnosis or relaxation) resulted in significant decreases in DBP in both experimental groups. In the control group there was a significant decrease in SBP. A specific suggestion to increase the BP resulted only in DBP increase in the hypnotic group. This group also gave an increase of both SBP and DBP over the entire experiment, whereas the relaxation group resulted in a significant decrease in SBP. There was no significant group variable, indicating no differences between the groups. Further research is needed to enable firm conclusions of the effect of suggestions on BP.  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