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   4000篇
  免费   247篇
  国内免费   3篇
  2024年   6篇
  2023年   35篇
  2022年   31篇
  2021年   63篇
  2020年   76篇
  2019年   115篇
  2018年   175篇
  2017年   185篇
  2016年   179篇
  2015年   126篇
  2014年   139篇
  2013年   451篇
  2012年   271篇
  2011年   277篇
  2010年   136篇
  2009年   170篇
  2008年   258篇
  2007年   238篇
  2006年   175篇
  2005年   157篇
  2004年   162篇
  2003年   162篇
  2002年   132篇
  2001年   53篇
  2000年   47篇
  1999年   41篇
  1998年   51篇
  1997年   41篇
  1996年   39篇
  1995年   32篇
  1994年   23篇
  1993年   27篇
  1992年   13篇
  1991年   13篇
  1990年   10篇
  1989年   13篇
  1988年   7篇
  1987年   12篇
  1986年   6篇
  1985年   11篇
  1984年   12篇
  1983年   8篇
  1982年   8篇
  1981年   8篇
  1980年   6篇
  1979年   6篇
  1978年   7篇
  1976年   6篇
  1974年   6篇
  1968年   5篇
排序方式: 共有4250条查询结果,搜索用时 15 毫秒
61.
Congenital bilateral absence of the vas deferens (CBAVD) occurs in approximately 1.3% of infertile males and is thought to be, in most cases, a primarily genital form of cystic fibrosis (CF). Fourteen males with CBAVD considering microsurgical sperm aspiration from the epididymis (MESA) and in vitro fertilization were seen for genetic counseling and screening for CF. To retrospectively evaluate these patients' perceptions of the counseling and screening information, we conducted structured telephone interviews to assess their recall of information about CF and its impact on their health concerns and reproductive plans. We found that, as the health implications of CF are abstract and not as important to patients as the diagnosis of CBAVD itself, patients tend to view their CF status primarily in terms of their reproductive potential. Retrospective analysis afforded us an opportunity to identify the psychosocial issues of most concern to this unique patient population.  相似文献   
62.
Most phonological investigations of aphasic speech have focused on consonants. In this study, the vowel substitutions of five English-speaking Broca's aphasics were investigated with respect to several major explanatory hypotheses. An important possible motivating factor for aphasic substitutions, phonological environment, is an unlikely origin for these errors, since most substitutions occur along the paradigmatic axis. Another prominent hypothesis, markedness, also has no predictive power for the data of this sample. However, an analysis of the five Chomsky and Halle (1968, (The Sound Pattern of English), New York: Harper and Row) vowel features indicates that the two features for vowel height are selectively impaired: There is a strong tendency for lower vowels to replace higher targets. Moreover, the substitution sounds tend to be close to their target sounds along the height axis. Four possible hypotheses are advanced to account for this consistent lowering tendency.  相似文献   
63.
64.
The present investigation focused upon the impact of gender and various powerful and less powerful linguistic features on the communication of unfamiliar male and female college students. Same-sex and mixed-sex dyads were recorded as they engaged in discussions regarding suggestions for a bogus freshman orientation booklet. Although few gender differences were found, the result of a factor analysis yielded three factors: questions, suggestions, and process variables. These factors are consistent with a power perspective in the use of various linguistic features. However, the present findings suggest that gender and power alone cannot explain differences in communication styles. Rather, the results suggest the need to consider other aspects of the speaker to explain differences that occur in the use of language.  相似文献   
65.
It is postulated that adult vocational maturity needs to be assessed because of the changing developmental tasks encountered during the course of a career. Vocational maturity having been found to be multidimensional, existing undimensional inventories of adult vocational maturity are considered of limited although demonstrated validity. Relevant theories of adult vocational development and adjustment are reviewed. Super's proposed adult vocational maturity model is examined for the promise that it offers and for the problems that arise in developing a multidimensional measure of vocational maturity. A way of surmounting these problems is proposed as a basis for work now being undertaken.  相似文献   
66.
The use of a self-recording and supervision program to increase interactions between direct care staff and profoundly retarded persons in a state residential facility was investigated. Following baseline, staff were provided with instructions regarding what to self-record, criteria for how many interactions to record, and a prepared card on which to make the recordings. Throughout the study, the staff supervisor monitored intermittently staff-client interactions. Observations indicated that when the staff recorded their interactions with clients in a loosely structured dayroom setting, the rate of interactions increased noticeably for each staff person. Behavioral ecology measures indicated that other staff responsibilities, such as maintaining the cleanliness of residents and the physical area, were not affected detrimentally when social interactions increased and actually showed small improvements. Additionally, small decreases in resident self-stimulatory and disruptive/aggressive behaviors occurred when the rate of social interactions from staff persons increased. Follow-up measures indicated that the rate of staff self-recording was variable, but when staff did self-record, the increased rate of staff-client interactions maintained.  相似文献   
67.
The duration and frequency of food presentation were varied in concurrent variable-interval variable-interval schedules of reinforcement. In the first experiment, in which pigeons were exposed to a succession of eight different schedules, neither relative duration nor relative frequency of reinforcement had as great an effect on response distribution as they have when they are manipulated separately. These results supported those previously reported by Todorov (1973) and Schneider (1973). In a second experiment, each of seven pigeons was exposed to only one concurrent schedule in which the frequency and/or duration of reinforcement differed on the two keys. Under these conditions, each pigeon's relative rate of response closely matched the relative total access to food that each schedule provided. This result suggests that previous failures to obtain matching may be due to factors such as an insufficient length of exposure to each schedule or to the pigeons' repeated exposure to different concurrent schedules.  相似文献   
68.
The stages of acquisition in stimulus fading   总被引:1,自引:1,他引:0       下载免费PDF全文
Pigeons were exposed to a stimulus fading procedure in which control of responding was transferred from red and black stimuli to lines of different angular orientation. After superimposing one line on the red stimulus and the other line on the black stimulus, the intensity of the lines was gradually increased and that of the red stimulus was gradually reduced. Probes consisting of red and line stimuli presented separately were used during the course of fading to assess control exerted by each element of the compound. As the lines were faded in, they did not acquire control of responding. As red was faded out, control of responding was acquired first by the lower intensity red stimuli in combination with the line stimulus, and finally by the angular orientation of the lines. Probes also determined the point at which the line stimuli, presented alone, would maintain a high degree of stimulus control. The results demonstrated that new stimuli in fading acquire dimensional control of responding in two sequential stages. Acquisition of stimulus control in fading was explained in terms of attenuation of stimulus blocking.  相似文献   
69.
70.
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