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91.
一般进化在系统内微观子系统层次上的微观机制 ,是涨落单元内外部子系统之间互为因果循环的正反馈类型的相互作用。其本质特征 ,是双方之间作用的非对称性 ,表现为一方的属性支配着另一方属性的变化 ,另一方丧失自己原先的属性而以一方的属性为自己的新属性。这种相互作用同时具有协同和放大效应 ,从而使涨落单元由局部迅速放大到整体 ,而形成一个新的有序结构  相似文献   
92.
This paper describes a technique for computing approximate maximum pseudolikelihood estimates of the parameters of a spatial point process. The method is an extension of Berman & Turner's (1992) device for maximizing the likelihoods of inhomogeneous spatial Poisson processes. For a very wide class of spatial point process models the likelihood is intractable, while the pseudolikelihood is known explicitly, except for the computation of an integral over the sampling region. Approximation of this integral by a finite sum in a special way yields an approximate pseudolikelihood which is formally equivalent to the (weighted) likelihood of a loglinear model with Poisson responses. This can be maximized using standard statistical software for generalized linear or additive models, provided the conditional intensity of the process takes an 'exponential family' form. Using this approach a wide variety of spatial point process models of Gibbs type can be fitted rapidly, incorporating spatial trends, interaction between points, dependence on spatial covariates, and mark information.  相似文献   
93.
94.
Characterizing all possible chemical mixtures in drinking water is a potentially overwhelming project, and the task of assessing each mixture's net toxicity even more daunting. We propose that analyzing occurrence information on mixtures in drinking water may help to narrow the priorities and inform the approaches taken by researchers in mixture toxicology. To illustrate the utility of environmental data for refining the mixtures problem, we use a recent compilation of national ground-water-quality data to examine proposed U.S. Environmental Protection Agency (EPA) and Agency for Toxic Substances and Disease Registry (ATSDR) models of noncancer mixture toxicity. We use data on the occurrence of binary and ternary mixtures of arsenic, cadmium, and manganese to parameterize an additive model and compute hazard index scores for each drinking-water source in the data set. We also use partially parameterized interaction models to perform a bounding analysis estimating the interaction potential of several binary and ternary mixtures for which the toxicological literature is limited. From these results, we estimate a relative value of additional toxicological information for each mixture. For example, we find that according to the U.S. EPA's interaction model, the levels of arsenic and cadmium found in U.S. drinking water are unlikely to have synergistic cardiovascular effects, but the same mixture's potential for synergistic neurological effects merits further study. Similar analysis could in future be used to prioritize toxicological studies based on their potential to reduce scientific and regulatory uncertainty. Environmental data may also provide a means to explore the implications of alternative risk models for the toxicity and interaction of complex mixtures.  相似文献   
95.
广告学本科专业的传播学理论课程教学思考   总被引:2,自引:0,他引:2  
传播学理论是广告学专业的理论基础课,它为进一步全面、深入学习和掌握广告学的其它课程奠定理论基础。为保证传播学教学的科学高效,应该把握以下三点:始终坚持传播学教学理念的专业关切性,始终坚持传播学教学内容的优化与整合,始终坚持传播学教学方法的互动性与灵活性。  相似文献   
96.
This paper examines family interactions between mothers and children in single‐parent‐by‐choice (SPBC) families in Spain. The data is part of a larger multi‐sited ethnographic study focused on emergent family structures that examined families formed by women who began their family projects through adoption or assisted reproduction. Single‐mothers‐by‐choice formulate various socialization goals that are tied to the complexities of their non‐conventional family project. These goals are also realized in daily conversation, particularly when families talk about future events in their lives. Our findings expand existing family language socialization research in Western contexts, which has primarily focused on conventional two‐parent families, and invite developing a stronger dialogue between family language socialization research and current debates on changing kinship structures in post‐industrial societies. Este trabajo examina interacciones entre madres e hijos/as en familias de madres solteras por elección (MSPE) en España. Los datos provienen de una investigación etnográfica multi‐lugar más amplia centrada en modelo familiares emergentes que estudió a familias formadas por mujeres solas que han comenzado su proyecto familiar a través de la reproducción asistida o la adopción. La madres solteras por elección formulan varias metas de socialización que están ligadas a las complejidades y demandas de su proyecto familiar no convencional. Estos objetivos también se plasman en conversaciones cotidianas, especialmente cuando las familias hablan sobre eventos futuros en su vidas. Nuestros resultados amplían la investigación sobre socialización lingüística familiar en contextos occidentales, que se ha centrado principalmente en familias bi‐parentales convencionales, e invitan a desarrollar un diálogo más fructífero entre la investigación sobre socialización lingüística familiar y los debates actuales en torno a cambios en los patrones de parentesco en sociedades post‐industriales. [Spanish]  相似文献   
97.
The aim of this article is to discuss some of the leading features of Erving Goffman's action theory as an alternative to the ‘orthodox’ paradigms of sociology, viewed as a structuralist and functionalist science that defines social constructs by their shared rules and values, and as a drifting of action, in the sense of intention, toward an individualistic version. The author examines Goffman's shift of the focus of attention from the boundaries of a social sense of action to the social dialectic of ‘defining a situation’ (W. Thomas) as conducted by the social actors in a renewal of Simmel's ‘empowering covenants’ (wechselwirkung) in the multiple casual social connections that make up the ‘social buzz’ in a society. The author moreover discusses Goffman's action as a kind of playacting regulating cognitive and expressive face-to-face ‘traffic’ between the social actors. This relational dynamic creates an interactive play based on encounters – in which one's opening to another is fraught with risks of deception – regulated by trust as a central resource for social interactions. Trust, in its interpersonal and systemic variants, constitutes a universal social datum and an elementary precondition for social exchanges and the cooperation between individuals. Trust, thus, functions as comparer between reciprocal expectations and a regulator of freedom tending to the stability of the social system.  相似文献   
98.
In this paper social interaction is modeled as a consumer good. A model of household production is employed to derive the demand for social interaction. The model shows that the demand for social interaction is a function of its price, the price of other goods and income. The theory is tested with data from the General Social Survey and the results show that social interaction can be explained as the consequence of utility maximizing behavior by individuals. These results are in contrast to social capital theorists who have attributed these changes to factors such as increased community heterogeneity.  相似文献   
99.
Abstract.  Functional magnetic resonance imaging (fMRI) is a technique for studying the active human brain. During the fMRI experiment, a sequence of MR images is obtained, where the brain is represented as a set of voxels. The data obtained are a realization of a complex spatio-temporal process with many sources of variation, both biological and technical. We present a spatio-temporal point process model approach for fMRI data where the temporal and spatial activation are modelled simultaneously. It is possible to analyse other characteristics of the data than just the locations of active brain regions, such as the interaction between the active regions. We discuss both classical statistical inference and Bayesian inference in the model. We analyse simulated data without repeated stimuli both for location of the activated regions and for interactions between the activated regions. An example of analysis of fMRI data, using this approach, is presented.  相似文献   
100.
自信心是学生进行学习、生活,也是进行创造性学习工作的最重要的心理条件。兴趣是调动学生积极性、探求知识的内动力。只有发挥学生的主体作用,恰当实施兴趣教学,使"要我学"变为"我要学",才能提高课堂效率,达到较好的教学效果。  相似文献   
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