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131.
132.
为了探究压电陶瓷悬臂梁结构的驱动传感共位特性,笔者研究了以压电耦合悬臂梁样机分别作为传感器、驱动器和驱动传感共位时电流的变化规律,分析了压电悬臂梁被限位工作条件下其共位信号与空载状态信号的差异性,通过检测压电悬臂梁内部电流的变化来实现对压电悬臂梁驱动状态的共位检测。实验结果表明:在电压的激励下,压电悬臂梁在未被限位工作条件下,仅存在频率大小约为230 Hz的响应信号;压电悬臂梁在限位条件工作时,其采样信号在230 Hz和1 640 Hz附近处有明显响应,且仿真结果与实验结果误差均在4%以内。该实验结果证明了可将压电陶瓷悬臂梁内部电流变化所对应的特征频率作为其工作状态的判定。 相似文献
133.
骑岭三中学生学习心理状况的研究报告 总被引:1,自引:0,他引:1
我们采用心理测量法研究骑岭三中学生的学习心理状况,揭示农村初中学生的学习心理特点,为提高学生的学习质量服务.得到的结论是1)学生的总体智商平均为102.2;2)学习适应性处于中等水平,中下等、差等率略高于全国水平;3)心理问题检出率为12.038%. 相似文献
134.
We introduce two extreme methods to pairwisely compare ordered lists of the same length, viz. the comonotonic and the countermonotonic
comparison method, and show that these methods are, respectively, related to the copula T
M
(the minimum operator) and the Ł ukasiewicz copula T
L
used to join marginal cumulative distribution functions into bivariate cumulative distribution functions. Given a collection
of ordered lists of the same length, we generate by means of T
M
and T
L
two probabilistic relations Q
M
and Q
L
and identify their type of transitivity. Finally, it is shown that any probabilistic relation with rational elements on a
3-dimensional space of alternatives which possesses one of these types of transitivity, can be generated by three ordered
lists and at least one of the two extreme comparison methods. 相似文献
135.
J. C. W. Rayner O. Thas B. De Boeck 《Australian & New Zealand Journal of Statistics》2008,50(3):235-240
The Emerson (1968, Biometrics 24 , 695–701) recurrence relation has many important applications in statistics. However, the original derivation applied only to discrete distributions. In the following, a simple derivation is given that generalizes the Emerson recurrence relation to any distribution for which the necessary expectations exist. A modern application is outlined. 相似文献
136.
This paper deals with models and methods for count data derived from observations on pairing phenomena. Pairs formed from “similar” members are excluded. Various models are considered and analyzed. Particular emphasis is on developing methods for testing whether particular pairs are prone to occur more or less often than expected by chance. 相似文献
137.
Vidal Diaz De Rada 《International Review of Sociology》1999,9(3):387-389
How to Conduct Self‐administered and Mail Surveys, L. B. Bourque and E. P. Fielder, London, Sage Publications, 1995, 223 pp, £17.50 相似文献
138.
Daniele De Martini 《Pharmaceutical statistics》2011,10(2):89-95
The problem of estimating the sample size for a phase III trial on the basis of existing phase II data is considered, where data from phase II cannot be combined with those of the new phase III trial. Focus is on the test for comparing the means of two independent samples. A launching criterion is adopted in order to evaluate the relevance of phase II results: phase III is run if the effect size estimate is higher than a threshold of clinical importance. The variability in sample size estimation is taken into consideration. Then, the frequentist conservative strategies with a fixed amount of conservativeness and Bayesian strategies are compared. A new conservative strategy is introduced and is based on the calibration of the optimal amount of conservativeness – calibrated optimal strategy (COS). To evaluate the results we compute the Overall Power (OP) of the different strategies, as well as the mean and the MSE of sample size estimators. Bayesian strategies have poor characteristics since they show a very high mean and/or MSE of sample size estimators. COS clearly performs better than the other conservative strategies. Indeed, the OP of COS is, on average, the closest to the desired level; it is also the highest. COS sample size is also the closest to the ideal phase III sample size MI, showing averages and MSEs lower than those of the other strategies. Costs and experimental times are therefore considerably reduced and standardized. However, if the ideal sample size MI is to be estimated the phase II sample size n should be around the ideal phase III sample size, i.e. n?2MI/3. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
139.
This paper considers the difficulties associated with evaluating the expected value of additional information when the outcomes of various decision alternatives may be correlated. Such correlation is explained in terms of dependence of outcomes on common exogenous factors and it is argued that decisions regarding what, if any, additional information to collect should take such dependencies into account. A model-based ‘fixed-parameter’ approach to evaluating EVPI in such a context is developed and compared to the traditional ‘fixed-correlation’ approach. The results suggest that different assumptions about the issue of correlation can produce different, sometimes contradictory, conclusions about the expected value of additional information and bence, should be explicitly stated as part of any pre-posterior analysis. A hybrid model encompassing both approaches and rooted in the theory of psychology of inference is then proposed and illustrated. 相似文献
140.
In this article we discuss some theoretical and methodological perspectives for studying children's neighbourhoods as a social‐pedagogical context. This social‐pedagogical perspective includes a focus in research on a reflective approach based on the acquisition of empirical indicators about the impact of the neighbourhood on children's socialisation. A research outline based on the idea of mapping children's neighbourhoods within their social and historical context is presented as one possible example of such an analysis. 相似文献