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921.
Beyond the five-user assumption: Benefits of increased sample sizes in usability testing 总被引:1,自引:0,他引:1
It is widely assumed that 5 participants suffice for usability testing. In this study, 60 users were tested and random sets
of 5 or more were sampled from the whole, to demonstrate the risks of using only 5 participants and the benefits of using
more. Some of the randomly selected sets of 5 participants found 99% of the problems; other sets found only 55%. With 10 users,
the lowest percentage of problems revealed by any one set was increased to 80%, and with 20 users, to 95%. 相似文献
922.
Christopher?A.?KurbyEmail author Katja?Wiemer-Hastings Nagasai?Ganduri Joseph?P.?Magliano Keith?K.?Millis Danielle?S.?McNamara 《Behavior research methods》2003,35(2):244-250
The effectiveness of a domain-specific latent semantic analysis (LSA) in assessing reading strategies was examined. Students were given self-explanation reading training (SERT) and asked to think aloud after each sentence in a science text. Novice and expert human raters and two LSA spaces (general reading, science) rated the similarity of each think-aloud protocol to benchmarks representing three different reading strategies (minimal, local, and global). The science LSA space correlated highly with human judgments, and more highly than did the general reading space. Also, cosines from the science LSA spaces can distinguish between different levels of semantic similarity, but may have trouble in distinguishing local processing protocols. Thus, a domain-specific LSA space is advantageous regardless of the size of the space. The results are discussedin the context of applying the science LSA to a computer-based version of SERT that gives online feedback based on LSA cosines. 相似文献
923.
The focus of this study is the effect of the location (laboratory vs. Web) of experiments on active information searchin decision-making tasks. In two experiments, participants were confronted with two different search method versions (list vs. keyword) for acquiring information about a task from a database. The amount and type of information gathered and the time required for task completion were measured. In Experiment 1, significantly more information was searched for in the laboratory than on the Web when the list version was employed, whereas there was no difference between locations in the keyword version. In Experiment 2, the participants were assigned randomly to the Web or the laboratory condition. The results of Experiment 1 were replicated. Whereas location (and the presence or absence of an experimenter) had an effect on the absolute amount of information gathered in both experiments, the relative distribution and type of information items did not differ. 相似文献
924.
Kristine?Y.?HogartyEmail author Jeffrey?D.?KromreyEmail author 《Behavior research methods》2003,35(4):585-589
In contrast to prospective power analysis, retrospective power analysis provides an estimate of the statistical power of a hypothesis test after an investigation has been conducted rather than before. In this article, three approaches to obtaining point estimates of power and an interval estimation algorithm are delineated. Previous research on the bias and sampling error of these estimates is briefly reviewed. Finally, an SAS macro that calculates the point and interval estimates is described. The macro was developed to estimate the power of anF test (obtained from analysis of variance, multiple regression analysis, or any of several multivariate analyses), but it may be easily adapted for use with other statistics, such as chi-square tests ort tests. 相似文献
925.
Harri?tte?RieseEmail author Paul?F.?C.?Groot Mireille?van den?Berg Nina?H.?M.?Kupper Ellis?H.?B.?Magnee Ellen?J.?Rohaan Tanja?G.?M.?Vrijkotte Gonneke?Willemsen Eco?J.?C.?de?Geus 《Behavior research methods》2003,35(3):467-477
Impedance cardiography has been used increasingly to measure human physiological responses to emotional and mentally engaging stimuli. The validity of large-scale ensemble averaging of ambulatory impedance cardiograms was evaluated for preejection period (PEP), interbeat interval, and dZ/dt(min) amplitude. We tested whether the average of “classical” 60-sec ensemble averages across periods with fixed activity, posture, physical load, social situation, and location could be accurately estimated from a single large-scale ensemble average spanning these entire periods. Impedance and electrocardiograms were recorded for about 24-h from 21 subjects. Recordings were scored by seven raters, using both methods for each subject. Good agreement (average intraclass correlation coefficient was .91) between both ensemble averaging methods was found for all three cardiac function measures. The results indicate that for unambiguous ambulatory impedance cardiograms, large-scale ensemble averaging is valid, which makes measuring prolonged changes in cardiac sympathetic activity by measuring ambulatory PEP feasible even in large epidemiological samples. 相似文献
926.
Although use of the standardized mean difference in meta-analysis is appealing for several reasons, there are some drawbacks. In this article, we focus on the following problem: that a precision-weighted mean of the observed effect sizes results in a biased estimate of the mean standardized mean difference. This bias is due to the fact that the weight given to an observed effect size depends on this observed effect size. In order to eliminate the bias, Hedges and Olkin (1985) proposed using the mean effect size estimate to calculate the weights. In the article, we propose a third alternative for calculating the weights: using empirical Bayes estimates of the effect sizes. In a simulation study, these three approaches are compared. The mean squared error (MSE) is used as the criterion by which to evaluate the resulting estimates of the mean effect size. For a meta-analytic dataset with a small number of studies, theMSE is usually smallest when the ordinary procedure is used, whereas for a moderate or large number of studies, the procedures yielding the best results are the empirical Bayes procedure and the procedure of Hedges and Olkin, respectively. 相似文献
927.
Edwin?D.?Ayers Jeffrey?White D.?A.?PowellEmail author 《Integrative psychological & behavioral science》2003,38(3):230-247
Several recent studies have investigated relationships between post-traumatic stress disorder (PTSD) and learning and memory
problems. These reports have found in general that not only does PTSD affect trauma-related memories, but when patients with
PTSD are compared with similar trauma patients without PTSD, general memory impairments have been found. The present paper
reports a study in which associative learning, using Pavlovian eyeblink conditioning, was investigated in combat veterans
with and without chronic PTSD, using interstimulus intervals of 500 and 1000 msec in two separate experiments. Although several
recent reports suggest that larger-magnitude autonomic conditioned responses occur in patients with PTSD during Pavlovian
conditoning, the present study found evidence of impaired Pavlovian eyeblink conditioning in combat veterans with and without
PTSD, compared to non-combat veterans. Although these data suggest that combat leads to an impaired associative learning process
regardless of whether PTSD is apparent, a group of community-dwelling combat veterans not under medical treatment showed normal
conditioning, suggesting that variables other than prior combat must also be involved. 相似文献
928.
Mark F. Ettin 《Group》2001,25(4):253-298
There is a reconsideration and renaissance of interest in expanded conceptions of unconscious processes as they affect individuals and groups (Grotstein, 1999). Recent focus on social unconscious (Hopper, 1996) and cultural unconscious processes (Henderson, 1988) and the nature of intersubjectivity (Harwood and Pines, 1998) raise questions about the location of group analysis. This paper considers the deep structure of group life by examining four functions of the unconscious: repressive, conservative, creative, and mythopoetic (Ellenberger, 1970). On an individual level of analysis, these functions are equated respectively with formative ideas about the: personal–subjective, social–political, intersubjective–cultural and collective–objective unconscious. Group level analogs, as they develop and affect groups and their members, are explored as synthetic, shared, symbolicy and synchronous unconscious processes. 相似文献
929.
Body-image disturbances and low self-esteem have been implicated in the pathogenesis of eating disorders. This study investigated self-perception of body and personality among adolescent ballet dancers in a cross-sectional survey. Two questionnaires assessing "my body right now" and "my personality right now," using semantic differentials were completed by 90 ballet school students and 156 controls. Adolescent female dancers (ages 13 to 17 years) scored higher than age-matched controls and 11- to 12-yr. old peers on Undesirability and Sensitivity for personality and Unattractiveness for body. For both subscales of personality, differences were also found between male and female dancers; female ballet students scored higher. Within the control group a difference could be found only for Sensitivity on which girls scored higher than boys. Male dancers did not differ from controls except for a lower score on the Body mass measure. Adolescent female dancers showed a distinct answering profile for 7 of 16 semantic differentials in each questionnaire implicating less favorable body image and self-esteem. Interventions focused particularly on enhancing self-esteem may be useful in the prevention of psychopathology in adolescent ballet dancers. 相似文献
930.
Formal models of categorization make different predictions about the theoretical importance of linear separability. Prior research, most of which has failed to find support for a linear separability constraint on category learning, has been conducted using tasks that involve learning two categories with a small number of members. The present experiment used four categories with three or nine patterns per category that were either linearly separable or not linearly separable. With overall category structure equivalent across category types, the linearly separable categories were found to be easier to learn than the not linearly separable categories. An analysis of individual participants' data showed that there were more participants operating under a linear separability constraint when learning large categories than when learning small ones. Formal modeling showed that an exemplar model could not account for many of these data. These results are taken to support the existence of multiple processes in categorization. 相似文献