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201.
This article presents a derivation of the distribution of the Kolmogorov–Smirnov, Cramer–von Mises, and Anderson–Darling test statistics in the case of exponential sampling when the parameters are unknown and estimated from sample data for small sample sizes via maximum likelihood.  相似文献   
202.
Overview of Recent Developments in Ecotoxicological Risk Assessment   总被引:1,自引:1,他引:1  
  相似文献   
203.
Brand  Kevin P.  Rhomberg  Lorenz  Evans  John S. 《Risk analysis》1999,19(2):295-308
The prominent role of animal bioassay evidence in environmental regulatory decisions compels a careful characterization of extrapolation uncertainties. In noncancer risk assessment, uncertainty factors are incorporated to account for each of several extrapolations required to convert a bioassay outcome into a putative subthreshold dose for humans. Measures of relative toxicity taken between different dosing regimens, different endpoints, or different species serve as a reference for establishing the uncertainty factors. Ratios of no observed adverse effect levels (NOAELs) have been used for this purpose; statistical summaries of such ratios across sets of chemicals are widely used to guide the setting of uncertainty factors. Given the poor statistical properties of NOAELs, the informativeness of these summary statistics is open to question. To evaluate this, we develop an approach to calibrate the ability of NOAEL ratios to reveal true properties of a specified distribution for relative toxicity. A priority of this analysis is to account for dependencies of NOAEL ratios on experimental design and other exogenous factors. Our analysis of NOAEL ratio summary statistics finds (1) that such dependencies are complex and produce pronounced systematic errors and (2) that sampling error associated with typical sample sizes (50 chemicals) is non-negligible. These uncertainties strongly suggest that NOAEL ratio summary statistics cannot be taken at face value; conclusions based on such ratios reported in well over a dozen published papers should be reconsidered.  相似文献   
204.
Quasiextinction Probabilities as a Measure of Impact on Population Growth   总被引:3,自引:0,他引:3  
A probabilistic language based on stochastic models of population growth is proposed for a standard language to be used in environmental assessment. Environmental impact on a population is measured by the probability of quasiextinction. Density-dependent and independent models are discussed. A review of one-dimensional stochastic population growth models, the implications of environmental autocorrelation, finite versus "infinite" time results, age-structured models, and Monte Carlo simulations are included. The finite time probability of quasiextinction is presented for the logistic model. The sensitivity of the result with respect to the mean growth rate and the amplitude of environmental fluctuations are examined. Stochastic models of population growth form a basis for formulating reasonable criteria for environmental impact estimates.  相似文献   
205.
206.
The following article by Keith Whyte represents the first of occasionally reprinted publications that are relevant to important historical events in the field of gambling studies. This article describes the act that led to the formation of the National Gambling Impact Study Commission. This Commission released its findings to the President and Congress of the United States during June of 1999.  相似文献   
207.
This paper identifies partner selection criteria in a sample of UK international joint ventures with Western European, US and Japanese partners. Rankings of selection criteria are derived for the sample using a typology that distinguishes between task-related and partner-related selection criteria. The most important task-related criteria are found to be access to knowledge of local market, access to distribution channels, access to links with major buyers and access to knowledge of local culture. The most important partner-related selection criteria are trust between the top management teams, relatedness of partner's business and reputation. A parsimonious set of selection criteria for the sample is provided by means of factor analysis. Hypotheses are tested on the relationship between the relative importance of selection criteria and a number of characteristics of the sample—partner nationality, industry of the joint ventures, joint-venture purpose, geographical location of the venture, initial approach for joint-venture formation and relative partner size. The greatest variation in the relative importance of selection criteria occurs with the geographic location of the joint venture.  相似文献   
208.
The major purpose of this article is to explore the substantial disparity between access to resources provided at birth to a child with spina bifida--a so-called Baby Doe--and later access to resources needed to sustain that child throughout the life course. The author's organizing principle is the allocative paradoxes created by the clash of technology, scarcity, and demography. The study is based on an eight-year inquiry into the way life-saving medical decisions are made about children with spina bifida. This work focuses on the qualitative aspects of that inquiry. There is a societal need to debate health care rationing, to do much more systematic technology assessment, and to develop a much more consistently rational system of health care delivery.  相似文献   
209.
Mortality experienced in the first three years of follow-up for three Established Populations for Epidemiologic Studies of the Elderly (EPESE) is examined in relation to the participants' self-reported functional ability. In East Boston, Massachusetts (N = 3,812), Iowa and Washington Counties, Iowa (N = 3,673), and New Haven, Connecticut (N = 2,812), noninstitutionalized persons aged 65 and older were asked a series of questions to determine their functional status. These measures, used in logistic regression analyses of the mortality data, showed that an increased number of reported disabilities significantly increased the risk of mortality over and above the effects of the age and sex of the participant, or the methodological differences among the sites. Disabilities in gross mobility (e.g., ability to walk a half mile, climb stairs, or perform heavy work around the house) were more strongly related to mortality than were measures of activities of daily living.  相似文献   
210.
This paper investigates the interaction between the economics of production and imperfections in the production process. Specifically, this paper is the first to devise a model in an attempt to provide managers with guidelines to choose the appropriate production run times to buffer against both the production of defective items and stoppages occurring due to machine breakdowns. In addition to providing several structural properties of the model, we show that a manager will always incur a cost penalty when (s)he uses the results of two oft‐cited models‐the EMQ (Economic Order/Manufacturing Quantity) and the NR‐E (No‐Resumption, Exponential machine breakdown)‐to determine production run times.  相似文献   
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