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941.
Workplace exposures to airborne chemicals are regulated in the U.S. by the Occupational Safety and Health Administration (OSHA) via the promulgation of permissible exposure limits (PELs). These limits, usually defined as eight-hour time-weighted average values, are enforced as concentrations never to be exceeded. In the case of chronic or delayed toxicants, the PEL is determined from epidemiological evidence and/or quantitative risk assessments based on long-term mean exposures or, equivalently, cumulative lifetime exposures. A statistical model was used to investigate the relation between the compliance strategy, the PEL as a limit never to be exceeded, and the health risk as measured by the probability that an individual's long-term mean exposure concentration is above the PEL. The model incorporates within-worker and between-worker variability in exposure, and assumes the relevant distributions to be log-normal. When data are inadequate to estimate the parameters of the full model, as it is in compliance inspections, it is argued that the probability of a random measurement being above the PEL must be regarded as a lower bound on the probability that a randomly selected worker's long-term mean exposure concentration will exceed the PEL. It is concluded that OSHA's compliance strategy is a reasonable, as well as a practical, means of limiting health risk for chronic or delayed toxicants. 相似文献
942.
This article shows that in Nepal breastfeeding almost completely explains the effects of following birth interval on childhood mortality during the first 18 months of age and partially explains the effect of following birth interval on childhood mortality between 18 and 60 months of age. Breastfeeding does not explain the effect of preceding birth interval on childhood mortality. The analysis is based on application of hazard models to data from the 1976 Nepal Fertility Survey. 相似文献
943.
944.
Abstract The effects of previous victimization, distance from law enforcement and neighbors, and sufficiency of police patrols on fear of crime are estimated using data from Montana farmers and ranchers. Victimization has the strongest direct effect. Distance from police and neighbors seems to heighten sensitivity to lesser police patrol activity in isolated areas, which in turn increases concern about criminal victimization. Fear of crime in rural farm areas reflects, in part, the spatial arrangements and related consequences of living in these regions. 相似文献
945.
Arvid Kappas Ursula Hess Carol L. Barr Robert E. Kleck 《Journal of Nonverbal Behavior》1994,18(4):263-280
Two studies were conducted using video records of real faces and three-dimensional schematic faces to investigate the perceptual distortions introduced by viewing faces at a vertical angle and their influence on the attribution of emotional expressions and attitudes. The results indicate that faces seen from below were perceived as morepositive and lessnegative, while faces seen from above appeared morenegative and lesspositive. This effect seems to be moderated by interindividual differences in facial morphology, and perhaps by differences in dynamic aspects of expressions. The second study investigated the respective contribution of the upper half and the lower half of the face to the perceptual distortion found. In general, judges based their attributions of emotional state more on cues from the upper half of the face. 相似文献
946.
947.
Examinations constitute one of the principal methods by which professions assess minimal competence in aspiring practitioners. The Examination in Marital and Family Therapy is used by most states which regulate the profession. This article provides the rationale for the examination program, describes its development and maintenance, and presents the knowledge base it samples. Administrative policies and procedures are also discussed as an aid to prospective licensure and certification candidates. 相似文献
948.
949.
We consider an economy with non-Samuelsonian public goods and we focus on linear cost sharing. In a linear cost sharing equilibrium
all agents in the economy optimize given a certain fixed cost share to be contributed towards the provision of public goods in the economy. Hence, each agent pays
a certain fraction of the total establishment costs of public goods and these cost shares are common knowledge. We show that
for a certain fixed contribution scheme the resulting linear cost share equilibria are equivalent to corresponding core allocations,
in which the core is based on the integral of the individual cost shares. We also show that there is no equivalence of the
Foley core with cost share equilibria, even in well-behaved large economies.
Received: 16 August 1995/Accepted: 29 July 1996 相似文献
950.
Using a multimethod strategy, we identify and analyze mobilization processes associated with the rapid emergence of the 1989 Chinese Democracy Movement. We propose that the confluence of macro-, meso-, and micromobilization processes and linkages among them provide a more robust model for understanding social movement dynamics. While the Chinese Democracy Movement was facilitated by economic reforms, regime crises, delayed repression, and the presence of foreign journalists, institutional forces were not sufficient in explaining the rapid and extensive mobilization. Students were able to overcome deficits in organizational and media resources by co-opting extant networks and by developing resonant collective action frames. Their frame alignment strategies and nonviolent direct action tactics tended to resonate with ordinary people's observations and experiences as well as with traditional Chinese narratives of Confucianism, nationalism, and communism. State reactions and counterframings, on the other hand, failed to sway the masses. Instead, participation spread from a few hundred college students to millions of citizens and ended, tragically and ironically, with the "People's Army" slaughtering its own people around Tiananmen Square. 相似文献