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991.
Abstract The development of unit root tests continues unabated, with many recent contributions using techniques such as generalized least squares (GLS) detrending and recursive detrending to improve the power of the test. In this article, the relation between the seemingly disparate tests is demonstrated by algebraically nesting all of them as ratios of quadratic forms in normal variables. By doing so, and using the exact sampling distribution of the ratio, it is straightforward to compute, examine, and compare the test' critical values and power functions. It is shown that use of GLS detrending parameters other than those recommended in the literature can lead to substantial power improvements. The open and important question regarding the nature of the first observation is addressed. Tests with high power are proposed irrespective of the distribution of the initial observation, which should be of great use in practical applications. 相似文献
992.
This article engages with problems that are usually opaque: What trajectories do scientific debates assume, when does a scientific community consider a proposition to be a fact, and how can we know that? We develop a strategy for evaluating the state of scientific contestation on issues. The analysis builds from Latour's black box imagery, which we observe in scientific citation networks. We show that as consensus forms, the importance of internal divisions to the overall network structure declines. We consider substantive cases that are now considered facts, such as the carcinogenicity of smoking and the non-carcinogenicity of coffee. We then employ the same analysis to currently contested cases: the suspected carcinogenicity of cellular phones, and the relationship between vaccines and autism. Extracting meaning from the internal structure of scientific knowledge carves a niche for renewed sociological commentary on science, revealing a typology of trajectories that scientific propositions may experience en route to consensus. 相似文献
993.
This paper extends Lindley's measure of average information to the linear model, E(Y∣ß) = Xß. An expression which quantifies the average amount of information provided by the nxl vector of observations Y about the pxl vector of coefficient parameters ß will be derived. The effect of the structure of the regressor matrix, X, on the information measure is discussed. An information theoretic optimal design is characterized. Some applications are suggested. 相似文献
994.
The statistical inference problem on effect size indices is addressed using a series of independent two-armed experiments
from k arbitrary populations. The effect size parameter simply quantifies the difference between two groups. It is a meaningful
index to be used when data are measured on different scales. In the context of bivariate statistical models, we define estimators
of the effect size indices and propose large sample testing procedures to test the homogeneity of these indices. The null
and non-null distributions of the proposed testing procedures are derived and their performance is evaluated via Monte Carlo
simulation. Further, three types of interval estimation of the proposed indices are considered for both combined and uncombined
data. Lower and upper confidence limits for the actual effect size indices are obtained and compared via bootstrapping. It
is found that the length of the intervals based on the combined effect size estimator are almost half the length of the intervals
based on the uncombined effect size estimators. Finally, we illustrate the proposed procedures for hypothesis testing and
interval estimation using a real data set. 相似文献
995.
Aesthetic approaches seek to enrich knowledge about the ‘sensible’ aspects of experience. The ‘aesthetic dimension’ of shipboard organizational life is evoked and co‐created through multiple aesthetic categories such as the agogic, the sacred, and the sublime rendered through multiple sensory experiences of life aboard. A researcher and sailor‐informant co‐authored aesthetic reading contributes to a growing niche of aesthetic‐based research within organization studies. Our article explores collaboration as an important element of the aesthetic project. Possibilities for future aesthetic inquiries are also considered. 相似文献
996.
Composite samples are formed by physically mixing samples. Usually, composite samples are used to reduce the overall cost associated with analytical procedures that must be performed on each sample, but they can also be used to protect the privacy of individuals. Composite sampling can reduce the cost of identifying individual cases that have a certain trait, such as those with a rare disease or those exceeding pollution-level standards. Not much is lost by applying this method as long as the trait is relatively rare. Composite sampling can reduce the cost of estimating the mean of some process. When samples are composited, the ability to estimate the variance is lost. In spite of this, the potential savings are so great that composite samples have been used. Much of this paper deasl with the variance of estimators based on composite sampling when the porportions of hte original samples comprising the composite sample are actually random. Taking repeated samples and measurements on several composite samples complicates the prodcedure, but allows the estimation of between and within variation as well as measurement error. 相似文献
997.
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999.
K. S. Sultan A. S. Al-Moisheer 《Journal of Statistical Computation and Simulation》2013,83(3):405-416
The classification of a random variable based on a mixture can be meaningfully discussed only if the class of all finite mixtures is identifiable. In this paper, we find the maximum-likelihood estimates of the parameters of the mixture of two inverse Weibull distributions by using classified and unclassified observations. Next, we estimate the nonlinear discriminant function of the underlying model. Also, we calculate the total probabilities of misclassification as well as the percentage bias. In addition, we investigate the performance of all results through a series of simulation experiments by means of relative efficiencies. Finally, we analyse some simulated and real data sets through the findings of the paper. 相似文献
1000.
Andrew T. A. Wood 《统计学通讯:模拟与计算》2013,42(4):1439-1456
A three-parameter F approximation to the distribution of a positive linear combination of central chi-squared variables is described. It is about as easy to implement as the Satterthwaite-Welsh and Hall-Buckley-Eagleson approximations. Some reassuring properties of the F approximation are derived, and numerical results are presented. The numerical results indicate that the new approximation is superior to the Satterthwaite approximation and, for some purposes, better than the Hall-Buckley-Eagleson approximation. It is not quite as good as the Gamma-Weibull approximation due to Solomon and Stephens, but is easier to implement because iterative methods are not required. 相似文献