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251.
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Using a large stated preference survey conducted across the U.S. and Canada, we assess differences in individual willingness
to pay (WTP) for health risk reductions between the two countries. Our utility-theoretic choice model allows for systematically varying
marginal utilities for avoided future time in different adverse health states (illness-years, recovered/remission years, and
lost life-years). We find significant differences between Canadian and U.S. preferences. WTP also differs systematically with age, gender, education, and marital status, as well as a number of attitudinal and subjective
health-perception variables. Age profiles for WTP are markedly different across the two countries. Canadians tend to display flatter age profiles, with peak WTP realized at older ages. 相似文献
254.
This paper formulates and axiomatizes utility models for denumerable time streams that make no commitment in regard to discounting future outcomes. The models address decision under certainty and decision under risk. Independence assumptions in both contexts lead to additive or multiplicative utilities over time periods that allow unambiguous comparisons of the relative importance of different periods. The models accommodate all patterns of future valuation. This discount-neutral feature is attained by restricting preference comparisons to outcome streams or probability distributions on outcome streams that differ in at most a finite number of periods. 相似文献
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256.
Peter B. Shaw 《Researches on Population Ecology》1985,27(1):1-23
Summary A detailed sensitivity analysis of a model of a predator-prey system comprised ofTetranychus urticae andPhytoseiulus persimilis was performed. The aim was to assess the relative importance of the life history parameters of both species, the functional
response, and the components of the numerical response. In addition, the impact of the initial predator-prey ratio and the
timing of predator introduction were tested. Results indicated that the most important factors in the system were relative
rates of predator and prey development, the time of onset of predator oviposition, and the mode of the predator's oviposition
curve. The total oviposition of the predator, the effect of prey consumption on predator oviposition, and predator searching
were important under some conditions. Factors of moderate importance were the adult female predator's functional response,
total prey oviposition, the mode of the prey's oviposition curve, abiotic mortality of the pre-adult predator, and the effect
of prey consumption on predator development and on the immature predator's mortality. Factors of least importance were the
variances of the predator's and prey's oviposition curves, the abiotic mortality of the adult predator, the abiotic mortality
of the pre-adult and adult prey, the functional response of the nymphal and adult male predators, and the effect of prey consumption
on adult predator mortality. The sex ratios had little effect, except when the proportion of female predators was very low.
The initial predator-prey ratio and time of predator introduction had significant impacts on system behavior, though the patterns
of impact were different. 相似文献
257.
258.
Ethnicity as cognition 总被引:1,自引:0,他引:1
This article identifies an incipient and largely implicit cognitive turn in the study of ethnicity, and argues that it can be consolidated and extended by drawing on cognitive research in social psychology and anthropology. Cognitive perspectives provide resources for conceptualizing ethnicity, race, and nation as perspectives on the world rather than entities in the world, for treating ethnicity, race, and nationalism together rather than as separate subfields, and for re-specifying the old debate between primordialist and circumstantialist approaches. 相似文献
259.
Clinical trials and other types of studies often examine the effects of a particular treatment or experimental condition on a number of different response variables. Although the usual approach for analysing such data is to examine each variable separately, this can increase the chance of false positive findings. Bonferroni's inequality or Hotelling's T2 statistic can be employed to control the overall type I error rate, but these tests generally lack power for alternatives in which the treatment improves the outcome on most or all of the endpoints. For the comparison of independent groups, O'Brien (1984) developed a rank-sum type test that has greater power than the Bonferroni and T2 procedures when one treatment is uniformly better (i.e. for all endpoints) than the other treatment(s). In this paper we adapt the rank-sum test to studies involving paired data and demonstrate that it, too, has power advantages for such alternatives. Simulation results are described, and an example from a study measuring the effects of sleep loss on glucose metabolism is presented to illustrate the methodology. 相似文献
260.
Peter Atteslander 《International Review of Sociology》2007,17(3):489-494
Anomie is one of few social scientific terms with a wide claim to explain aspects of social change, in different cultures at different stages of modernization not to say globalization. In the early 1990s the Scientific Board of the Swiss Academy of Development commenced a research project which is still continuing with most of the same researchers but under the name of The International Network for the Assessment of Social Transformation (INAST), based in the Institute of Sociology, University of Neuchâtel, Switzerland. The work was importantly influenced by Robert K. Merton, an honorary member of the group. 相似文献