全文获取类型
收费全文 | 188444篇 |
免费 | 8398篇 |
国内免费 | 155篇 |
专业分类
196997篇 |
出版年
2020年 | 2783篇 |
2019年 | 3450篇 |
2018年 | 3672篇 |
2017年 | 4113篇 |
2016年 | 4749篇 |
2015年 | 3945篇 |
2014年 | 4833篇 |
2013年 | 23497篇 |
2012年 | 5003篇 |
2011年 | 4319篇 |
2010年 | 4116篇 |
2009年 | 4865篇 |
2008年 | 4451篇 |
2007年 | 4066篇 |
2006年 | 4503篇 |
2005年 | 4419篇 |
2004年 | 3887篇 |
2003年 | 3481篇 |
2002年 | 3339篇 |
2001年 | 4045篇 |
2000年 | 3913篇 |
1999年 | 3657篇 |
1998年 | 2898篇 |
1997年 | 2733篇 |
1996年 | 2643篇 |
1995年 | 2458篇 |
1994年 | 2415篇 |
1993年 | 2391篇 |
1992年 | 3037篇 |
1991年 | 2844篇 |
1990年 | 2689篇 |
1989年 | 2548篇 |
1988年 | 2537篇 |
1987年 | 2523篇 |
1986年 | 2560篇 |
1985年 | 2754篇 |
1984年 | 2748篇 |
1983年 | 2501篇 |
1982年 | 2443篇 |
1981年 | 2423篇 |
1980年 | 2247篇 |
1979年 | 2531篇 |
1978年 | 2328篇 |
1977年 | 2243篇 |
1976年 | 2048篇 |
1975年 | 2233篇 |
1974年 | 2315篇 |
1973年 | 2244篇 |
1972年 | 1830篇 |
1971年 | 1726篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
811.
Paul E. Meehl 《Journal of personality》1992,60(1):117-174
ABSTRACT A taxon is a nonarbitrary class whose existence is conjectured as an empirical question, not a mere semantic convenience. Numerous taxa are known to exist in nature and society (chemical elements, biological species, organic diseases, geological strata, kinds of stars, elementary particles, races, cultures, Mendelizing mental deficiencies, major psychoses, vocations, ideologies, religions). What personality types, if any, occur in the nonpathological population remains to be researched by sophisticated methods, and cannot be settled by fiat or "dimensional" preference. The intuitive concept of taxonicity is to be explicated by a combination of formal-numerical and causal criteria. Taxometric methods should include consistency tests that provide Popperian risk of strong discorroboration. In social science, latent class methods are probably more useful than cluster algorithms. 相似文献
812.
813.
Seventy-three married couples were studied in 1983 and 1987. To identify marital processes associated with dissolution, a balance theory of marriage was used to generate 1 variable for dividing couples into regulated and nonregulated groups. For studying the precursors of divorce, a "cascade" model of marital dissolution, which forms a Guttman-like scale, received preliminary support. Compared with regulated couples, nonregulated couples had (a) marital problems rated as more severe (Time 1); (b) lower marital satisfaction (Time 1 and Time 2); (c) poorer health (Time 2); (d) smaller finger pulse amplitudes (wives); (e) more negative ratings for interactions; (f) more negative emotional expression; (g) less positive emotional expression; (h) more stubbornness and withdrawal from interaction; (i) greater defensiveness; and (j) greater risk for marital dissolution (lower marital satisfaction and higher incidence of consideration of dissolution and of actual separation). 相似文献
814.
R C Barnett N L Marshall J D Singer 《Journal of personality and social psychology》1992,62(4):634-644
Are changes over time in the quality of a woman's job associated with changes in her psychological distress? Do family roles moderate these relationships? We addressed these questions using longitudinal data from a 2-year 3-wave study of a stratified random sample of 403 employed women who varied in occupation, race, partnership, and parental status. After estimating individual rates of change for each woman on each of the predictors and the outcome, we modeled the relationships between family role occupancy and change in job-role quality on the one hand, and change in psychological distress on the other. Among single women and women without children, as job-role quality declined, levels of psychological distress increased. Among partnered women and women with children, change in job-role quality was unrelated to change in psychological distress. 相似文献
815.
O Wiegman H Boer J M Gutteling E Komilis B Cadet 《The Journal of social psychology》1992,132(1):101-116
This article describes the different reactions to emergency warning messages among residents living within a 3-km radius of a hazardous chemical complex and by people living at least 10 km from an industrial site in France, Greece, and the Netherlands. Belief in warning, primary and secondary appraisal, emotional response, and adherence to normal routine were assessed by conducting face-to-face interviews in which a four-phase scenario simulating a credible industrial accident was presented. The results showed that respondents who did not reside in the neighborhood of the hazardous site were, in general, more inclined to trust the warning messages than respondents who resided in the neighborhood were. With the exception of primary appraisal, the warning phases evoked very distinct reactions in the respondents from all three countries with regard to warning belief, secondary appraisal, emotional response, and adherence to normal routine. 相似文献
816.
Choice with delayed and probabilistic reinforcers: effects of variability, time between trials, and conditioned reinforcers. 下载免费PDF全文
In a discrete-trials procedure with pigeons, a response on a green key led to a 4-s delay (during which green houselights were lit) and then a reinforcer might or might not be delivered. A response on a red key led to a delay of adjustable duration (during which red houselights were lit) and then a certain reinforcer. The delay was adjusted so as to estimate an indifference point--a duration for which the two alternatives were equally preferred. Once the green key was chosen, a subject had to continue to respond on the green key until a reinforcer was delivered. Each response on the green key, plus the 4-s delay that followed every response, was called one "link" of the green-key schedule. Subjects showed much greater preference for the green key when the number of links before reinforcement was variable (averaging four) than when it was fixed (always exactly four). These findings are consistent with the view that probabilistic reinforcers are analogous to reinforcers delivered after variable delays. When successive links were separated by 4-s or 8-s "interlink intervals" with white houselights, preference for the probabilistic alternative decreased somewhat for 2 subjects but was unaffected for the other 2 subjects. When the interlink intervals had the same green houselights that were present during the 4-s delays, preference for the green key decreased substantially for all subjects. These results provided mixed support for the view that preference for a probabilistic reinforcer is inversely related to the duration of conditioned reinforcers that precede the delivery of food. 相似文献
817.
Hanna ES Blackman DE Todorov JC 《Journal of the experimental analysis of behavior》1992,58(2):335-347
Six experimentally naive pigeons were exposed to concurrent variable-interval variable-interval schedules in a three-key procedure in which food reinforcement followed pecks on the side keys and pecks on the center key served as changeover responses. In Phase 1, 3 birds were exposed to 20 combinations of five variable-interval values, with each variable-interval value consistently associated with a different color on the side keys. Another 3 pigeons were exposed to the same 20 conditions, but with a more standard procedure that used a nondifferential discriminative stimulus on the two side keys throughout all conditions. In Phase 2, the differential and nondifferential stimulus conditions were reversed for each pigeon. Each condition lasted for one 5-hr session and one subsequent 1-hr session. In the last 14 conditions of each phase, the presence of differential discriminative stimuli decreased the time necessary for differential responding to develop and increased the sensitivity of behavior to reinforcement distribution in the 1st hr of training; during the last hours of training in each condition, however, the effects of the differential discriminative stimuli could not be distinguished from the effects of reinforcement distribution per se. These results show the importance of studying transitions in behavior as well as final performance. They may also be relevant to discrepancies in the results of previous experiments that have used nonhuman and human subjects. 相似文献
818.
In two experiments, key pecking of pigeons was maintained by a variable-interval 180-s schedule of food presentation. Conjointly, a second schedule delivered response-dependent electric shock. In the first experiment, shocks were presented according to either a variable-interval or a nondifferential interval-percentile schedule. The variable-interval shock schedule differentially delivered shocks following long interresponse times. Although the nondifferential shock schedules delivered shocks less differentially with respect to interresponse times, the two shock schedules equally reduced the relative frequency of long interresponse times. The second experiment differentially shocked long or short interresponse times in different conditions, with resulting decreases in the relative frequency of the targeted interresponse times. These experiments highlight the importance of selecting the appropriate level of analysis for the interaction of behavior and environment. Orderly relations present at one level of analysis (e.g., interresponse times) may not be revealed at other levels of analysis (e.g., overall response rate). 相似文献
819.
Dougan JD 《Journal of the experimental analysis of behavior》1992,58(3):415-429
Economic theory predicts an inverse relationship between the quantity of a commodity supplied to the marketplace and the equilibrium market price of that commodity. This prediction was tested in three experiments. Pigeons responded on simple variable-interval schedules, and quantity of reinforcement supplied was varied in a different way in each experiment. In Experiment 1, quantity supplied was varied by manipulating reinforcement rate while keeping session length constant. In Experiment 2, quantity supplied was varied by manipulating reinforcement rate while keeping reinforcers per session constant. In Experiment 3, quantity supplied was varied by manipulating reinforcer magnitude while keeping number of reinforcers constant. As predicted by economic theory, the obtained behavioral cost (responses per reinforcer) increased as supply decreased. The results could not be explained by simple artifacts such as satiation and time available to respond. In addition, the function relating response rate to reinforcement rate was bitonic in 7 of 9 animals in Experiments 1 and 2, which supports economic and regulatory theories over more traditional reinforcement theories. 相似文献
820.
R L Greene N C Weed J N Butcher R Arredondo H G Davis 《Journal of personality assessment》1992,58(2):405-410
We evaluated the efficacy of the Addiction Potential Scale (APS) and the Addiction Acknowledgement Scale (AAS), two new scales designed to assess substance abuse problems with the Minnesota Multiphasic Personality Inventory-2 (MMPI-2), in samples from settings different from those used in their development. Results replicate earlier findings that both scales discriminate between psychiatric and substance abuse samples and do so more effectively than other substance abuse scales designed for use with the MMPI and carried over to the MMPI-2. Results also suggest that APS may be more resistant than AAS to response distortion. 相似文献