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   7262篇
  免费   306篇
  国内免费   2篇
  2021年   87篇
  2020年   139篇
  2019年   114篇
  2018年   181篇
  2017年   170篇
  2016年   212篇
  2015年   160篇
  2014年   197篇
  2013年   698篇
  2012年   344篇
  2011年   347篇
  2010年   218篇
  2009年   209篇
  2008年   299篇
  2007年   319篇
  2006年   256篇
  2005年   280篇
  2004年   262篇
  2003年   242篇
  2002年   246篇
  2001年   125篇
  2000年   86篇
  1999年   117篇
  1998年   107篇
  1997年   108篇
  1996年   92篇
  1995年   81篇
  1994年   76篇
  1993年   84篇
  1992年   91篇
  1991年   84篇
  1990年   70篇
  1989年   50篇
  1988年   51篇
  1987年   58篇
  1986年   60篇
  1985年   74篇
  1984年   67篇
  1983年   72篇
  1982年   63篇
  1981年   76篇
  1980年   68篇
  1979年   68篇
  1978年   70篇
  1977年   73篇
  1976年   65篇
  1975年   55篇
  1974年   60篇
  1968年   43篇
  1966年   44篇
排序方式: 共有7570条查询结果,搜索用时 15 毫秒
971.
972.
Warning responses are described on the basis of interviews with 278 randomly selected families who were evacuated from their homes prior to a flood in Denver, Colorado, on June 16, 1965. Response patterns are analyzed in detail for families who were geographically separated at the time initial warnings were received. Numerous implications for community disaster planning are explicated.  相似文献   
973.
Forty-two years ago, Counts (1925) surveyed the social status of occupations and found a well-defined prestige order, with banker at the top and ditch digger at the bottom. Because of changes wrought by the depression and World War II, Deeg and Paterson (1947) repeated Counts' study and found only minor relative changes in social status. Because of the extensive social and cultural changes since World War II, Counts' study was repeated again, and again only minor relative changes in the social status of occupations were found. The prestige order of the occupations surveyed is remarkably stable.  相似文献   
974.
An information-theoretic model for the serial position effect   总被引:1,自引:0,他引:1  
  相似文献   
975.
Pigeons' responding was maintained by two concurrently available variable-interval reinforcement schedules. A fixed-ratio punishment schedule of timeout periods from the concurrent reinforcement schedules was arranged for responding during one of the variable-interval schedules. The greater the probability of a timeout after a response on the punished variable-interval schedule (the smaller the fixed ratio that produced timeout), the greater the decline in the relative punished response rates. Relative reinforcement rates remained invariant when relative response rates declined. Both behavioral contrast and induction effects were observed on the unpunished variable-interval schedule as a function of timeout punishment of the other schedule.  相似文献   
976.
The five pigeons in Group 1 were given successive intradimensional discrimination training in which responses to a line of 49 degrees were reinforced on a variable-interval schedule and responses to a line of 33 degrees were not reinforced. Subsequent generalization testing with other line orientations revealed a peak shift from the positive stimulus in the direction away from the negative stimulus in all subjects. The four pigeons in Group 2 received successive discrimination training with the 49 degrees value on the key during both stimuli. During the negative stimulus, however, the floor was tilted 16 degrees counterclockwise. When tested (with the floor flat) these subjects showed peak shifts similar to those observed with Group 1. A third group of three pigeons, given successive interdimensional discrimination training with the 49 degrees line as the positive stimulus and the absence of the line as the negative, showed no peak shift in a subsequent generalization test. It was concluded that tilting the floor on which the pigeon stood systematically distorted the bird's visual perception of the orientation of the line in a manner consistent with the results of other studies in this laboratory.  相似文献   
977.
Two bobwhite quail (Colinus virginianus) and two Japanese quail (Coturnix coturnix japonica) were trained to peck a response key to obtain food. In general, performance on fixed ratio 20 and variable- and fixed-interval 60-sec schedules was comparable to the response patterns of other species under these schedules.  相似文献   
978.
Rules, praise, and ignoring: elements of elementary classroom control   总被引:3,自引:0,他引:3  
An attempt was made to vary systematically the behavior of two elementary school teachers to determine the effects on classroom behavior of Rules, Ignoring Inappropriate Behaviors, and showing Approval for Appropriate Behavior. Behaviors of two children in one class and one child in the other class were recorded by observers, as were samples of the teachers' behavior. Following baseline recordings, Rules, Ignoring, and Approval conditions were introduced one at a time. In one class a reversal of conditions was carried out. The main conclusions were that: (a) Rules alone exerted little effect on classroom behavior, (b) Ignoring Inappropriate Behavior and showing Approval for Appropriate Behavior (in combination) were very effective in achieving better classroom behavior, and (c) showing Approval for Appropriate Behaviors is probably the key to effective classroom management.  相似文献   
979.
Two masking experiments were carried out. In the first, duration thresholds were measured for a 10 min black test disc paired with a larger concentric black mask, ranging in size from 15 min to 2 deg. The stimuli were tachistoscopically presented centrally, or at 2 deg or 6 deg in the left binocular field. As mask diameter increased, test threshold decreased in a negatively accelerated function, which approached an asymptote below the unmasked condition. All functions are similar with systematic upward shifts for more peripheral stimulation. In Experiment 2, threshold luminance was adjusted for a 1 deg, 5-msec test flash paired with a 250-mseC., 34-mL mask, ranging from 1 deg to 6.2 deg in diameter. Stimuli were presented in Maxwellian view at 7.2 deg in the right eye nasal field. Results were similar to Experiment 1, except that the asymptote is significantly above the control condition. Both experimental results support a border inhibition hypothesis.  相似文献   
980.
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