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911.
912.
Edward J. Bedrick 《Journal of applied statistics》2005,32(9):959-967
I consider the problem of estimating the Mahalanobis distance between multivariate normal populations when the population covariance matrix satisfies a graphical model. In addition to providing a clear understanding of the dependencies in a multivariate data set, the use of graphical models can reduce the variability of the estimated distances and improve inferences. I derive the asymptotic distribution of the estimated Mahalanobis distance under a general covariance model, which includes graphical models as a special case. Two examples are discussed. 相似文献
913.
Daniel M. Byrd III Donald O. Allen Robert L. Beamer Henry R. Besch Jr. David B. Bylund John Doull William W. Fleming Arthur Fries F. Peter Guengerich Roger Hornbrook Louis Lasagna Bert K. B. Lum Elias K. Michaelis Edward T. Morgan Alan Poland Karl K. Rozman J. Bryan Smith Hollie I. Swanson William Waddell James D. Wilson 《Risk analysis》1998,18(1):1-2
914.
A Pharmacokinetic Study of Occupational and Environmental Benzene Exposure with Regard to Gender 总被引:6,自引:0,他引:6
Using physiologically-based pharmacokinetic (PBPK) modeling, occupational, personal, and environmental benzene exposure scenarios are simulated for adult men and women. This research identifies differences in internal exposure due to physiological and biochemical gender differences. Physiological and chemical-specific model parameters were obtained from other studies reported in the literature and medical texts for the subjects of interest. Women were found to have a higher blood/air partition coefficient and maximum velocity of metabolism for benzene than men (the two most sensitive parameters affecting gender-specific differences). Additionally, women generally have a higher body fat percentage than men. These factors influence the internal exposure incurred by the subjects and should be considered when conducting a risk assessment. Results demonstrated that physicochemical gender differences result in women metabolizing 23–26% more benzene than men when subject to the same exposure scenario even though benzene blood concentration levels are generally higher in men. These results suggest that women may be at significantly higher risk for certain effects of benzene exposure. Thus, exposure standards based on data from male subjects may not be protective for the female population. 相似文献
915.
This article attempts to address the problem of multicollinearity in the estimation of educational production functions. Past studies consistently indicate the seeming lack of importance of school input variables such as teacher salary, class size, and expenditure per student in influencing educational outcomes. Our ordinary least squares results were consistent with these past studies, but collinearity diagnostics revealed the presence of at least four potentially serious sources of collinearity within the data, possibly degrading the coefficients on the school input variables. Ridge regression and principal components regression techniques were employed in an effort to “solve” the collinearity problem. The coefficients of the school input variables continue to have the hypothesized signs, but with smaller standard errors. The results indicate that researchers should be cautioned against reaching the conclusion that school input variables don't matter on the basis of ordinary least squares estimates of these parameters. 相似文献
916.
美国加利福尼亚州有这样一群"绿色妈妈",她们聚集在空气清新的客厅里,一边喝着红酒,一边说笑.她们的谈话很快就热烈起来--她们讨论的不是文学名著,也非名人八卦,而是各种可在家里落实的环保措施,比如抗菌洗手液的缺点、如何改造洗衣房以及在非能源使用高峰时段(晚7点后)只用冷水和生物降解洗涤剂洗衣服. 相似文献
917.
918.
Kevin M. Brown 《The Sociological review》1988,36(3):474-502
The article discusses fifteen feature films which re-present aspects of European/Aboriginal relations. Through an analysis of the narrative structures of the films, three basic themes are identified and outlined, each of which could be implicated in the processes through which racist ideology inheres in the encoding/decoding nexus. The concept of ‘racial’ register is utilised to signify the limits to these forms of representations. It is argued that at both the levels of the narrative theme (intertextual) and the syntagmatic (intratextual), the ‘racial’ register works to reconstruct ‘race’ as an overdetermined ideological notion which cements ideas of essential difference and fixes them to ideas of place. The article concludes with an examination of three films which lie partially outside the ‘racial’ register. 相似文献
919.
This qualitative research study explored the ways in which family therapists (MSWs) perceive the family treatment process. A purposive sample of eight practicing clinical social workers were selected for face to face interviews which explored the workers' perceptions of the family treatment process. Findings revealed that although certain consistent themes appear to exist among family therapists, family therapy practice may well be much more idiosyncratic than commonly believed. 相似文献
920.
The development of a new product is often a sequential-decision process with many available stages at which the product may take any one of a number of alternate courses of action. This paper identifies an efficient algorithm for solving this sequential-decision process. A computer program, involving the algorithm, has been written to solve problems containing up to one thousand stages. Input into the program includes the subjective probabilities of success for each decision branch, the cost associated with each decision stage and level, the rate for discounting all monetary values to the present plus an indicator for each decision stage and level of the desired decision criterion. The algorithm utilizes the dynamic-programming solution approach. The output of the algorithm contains the minimum, or maximum, expected discounted decision values for each stage and level of the network. The algorithm and computer program have been primarily utilized in the pharmaceutical industry. An illustrative, exemplary use of the algorithm in this industry is presented. 相似文献