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1.
文章首先运用归纳法,提出时间断点回归的概念内涵和基本模型,并按"准随机实验"标准分析其存在的原理缺陷。然后通过梳理国外相关前沿成果,总结出时间断点回归有别于传统计量操作的方面:在适用性判断上,强调内生分组问题的理论分析和协变量连续性的提前估计;在稳定性检验上,包含更换变量指标等正向思路、对照组检验等反向思路、时间序列特征处理和其他非断点回归方法。最后,绘制时间断点回归的估计流程图,主要涉及适用性检验、处理效应的初步判定、模型构建与估计和稳健性检验四个部分。  相似文献   
2.
在脱贫攻坚中,对重点贫困地区的精确瞄准与偏向投入,在一定程度上对非贫困县、非贫困村与非贫困户产生了必然的政策负外部性,表现为县域脱贫结构失衡、村庄帮扶悬崖效应与边缘人群争贫风险。究其原由,在公共政策过程中,竞争性的政策汲取、排他性的政策分配与分割性的政策评价是负外部性的三种发生机理。为此需要建立上下融合减贫机制,探索社区主导发展模式,拓展村民赋权参与空间,通过政策纠正、调适以消解和弥补政策负效应,强化政治决策与分配的正义性。  相似文献   
3.
基于3个农村改革试验区716个农户的微观数据,实证分析农户分化、乡土依赖对农户集体收益分配权退出意愿的影响。结果表明,农户的不断分化并未提高其集体收益分配权退出意愿,分化程度较高的农户更倾向于继续持有集体收益分配权,土地、宅基地的退出对集体收益分配权退出意愿未产生显著影响,但对所在村的心理依赖水平有着显著的反向影响,即在集体收益分配权的退出中,对其退出意愿产生影响的更多是农户对乡土的心理依赖,而非现实依赖。这要求在进一步探索中,既要有改革的紧迫感,完善退出机制,引导符合条件的农户理性退出集体收益分配权,也要有历史的耐心,充分尊重农户的乡土情结。  相似文献   
4.
The central limit theorem indicates that when the sample size goes to infinite, the sampling distribution of means tends to follow a normal distribution; it is the basis for the most usual confidence interval and sample size formulas. This study analyzes what sample size is large enough to assume that the distribution of the estimator of a proportion follows a Normal distribution. Also, we propose the use of a correction factor in sample size formulas to ensure a confidence level even when the central limit theorem does not apply for these distributions.  相似文献   
5.
In this paper, we discuss some theoretical results and properties of the discrete Weibull distribution, which was introduced by Nakagawa and Osaki [The discrete Weibull distribution. IEEE Trans Reliab. 1975;24:300–301]. We study the monotonicity of the probability mass, survival and hazard functions. Moreover, reliability, moments, p-quantiles, entropies and order statistics are also studied. We consider likelihood-based methods to estimate the model parameters based on complete and censored samples, and to derive confidence intervals. We also consider two additional methods to estimate the model parameters. The uniqueness of the maximum likelihood estimate of one of the parameters that index the discrete Weibull model is discussed. Numerical evaluation of the considered model is performed by Monte Carlo simulations. For illustrative purposes, two real data sets are analyzed.  相似文献   
6.
In a Poisson process, it is well-known that the forward and backward recurrence times at a given time point t are independent random variables. In a renewal process, although the joint distribution of these quantities is known (asymptotically), it seems that very few results regarding their covariance function exist. In the present paper, we study this covariance and, in particular, we state both necessary and sufficient conditions for it to be positive, zero or negative in terms of reliability classifications and the coefficient of variation of the underlying inter-renewal and the associated equilibrium distribution. Our results apply either for an ordinary renewal process in the steady state or for a stationary process.  相似文献   
7.
In this article, we introduce tempered Mittag-Leffler Lévy processes (TMLLP). TMLLP is represented as tempered stable subordinator delayed by a gamma process. Its probability density function and Lévy density are obtained in terms of infinite series and Mittag-Leffler function, respectively. Asymptotic forms of the tails and moments are given. A step-by-step procedure of the parameters estimation and simulation of sample paths is given. We also provide main results available for Mittag-Leffler Lévy processes (MLLP) and some extensions which are not available in a collective way in a single article. Our results generalize and complement the results available on Mittag-Leffler distribution and MLLP in several directions. Further, the asymptotic forms of the moments of the first-exit times of the TMLLP are also discussed.  相似文献   
8.
In this paper, a new generalization of the Kumaraswamy distribution namely, the Kumaraswamy Marshall-Olkin Exponential distribution (KwMOE) is introduced and studied. Various properties are explored. The structural analysis includes various aspects such as limiting behaviour, shape properties, moments, quantiles, mean deviation, Renyi entropy, order statistics and stochastic ordering. Some useful characterizations of the family are also obtained. The method of maximum likelihood is used to estimate the model parameters. Monte Carlo simulation study is being conducted. An application to a real data set is presented for illustrative purposes.  相似文献   
9.
We propose novel parametric concentric multi‐unimodal small‐subsphere families of densities for p ? 1 ≥ 2‐dimensional spherical data. Their parameters describe a common axis for K small hypersubspheres, an array of K directional modes, one mode for each subsphere, and K pairs of concentrations parameters, each pair governing horizontal (within the subsphere) and vertical (orthogonal to the subsphere) concentrations. We introduce two kinds of distributions. In its one‐subsphere version, the first kind coincides with a special case of the Fisher–Bingham distribution, and the second kind is a novel adaption that models independent horizontal and vertical variations. In its multisubsphere version, the second kind allows for a correlation of horizontal variation over different subspheres. In medical imaging, the situation of p ? 1 = 2 occurs precisely in modeling the variation of a skeletally represented organ shape due to rotation, twisting, and bending. For both kinds, we provide new computationally feasible algorithms for simulation and estimation and propose several tests. To the best knowledge of the authors, our proposed models are the first to treat the variation of directional data along several concentric small hypersubspheres, concentrated near modes on each subsphere, let alone horizontal dependence. Using several simulations, we show that our methods are more powerful than a recent nonparametric method and ad hoc methods. Using data from medical imaging, we demonstrate the advantage of our method and infer on the dominating axis of rotation of the human knee joint at different walking phases.  相似文献   
10.
In this work, we assume that the sequence recording whether or not an ozone exceedance of an environmental threshold has occurred in a given day is ruled by a non-homogeneous Markov chain of order one. In order to account for the possible presence of cycles in the empirical transition probabilities, a parametric form incorporating seasonal components is considered. Results show that even though some covariates (namely, relative humidity and temperature) are not included explicitly in the model, their influence is captured in the behavior of the transition probabilities. Parameters are estimated using the Bayesian point of view via Markov chain Monte Carlo algorithms. The model is applied to ozone data obtained from the monitoring network of Mexico City, Mexico. An analysis of how the methodology could be used as an aid in the decision-making is also given.  相似文献   
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