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41.
The influence of neighborhoods on adolescent behaviors has received increasing research attention. In the present study, we use structural equation models to specify pathways from neighborhoods to adolescent cigarette and alcohol use through parental closeness, parental monitoring, parent substance use, and peer substance use. We use a national sample with 959 adolescents 12 to 14 years of age whose residential addresses were matched with 1990 Census tracts to provide neighborhood characteristics. We found that for adolescent cigarette use low socioeconomic status (SES) neighborhoods were associated with increased parental monitoring, which was further associated with decreased adolescent cigarette use. For adolescent alcohol use, high SES neighborhoods were associated with increased parent drinking, which was further associated with increased adolescent alcohol use. Low SES neighborhoods were associated with increased parental monitoring and increased peer drinking, which were in turn associated with decreased and increased adolescent alcohol use, respectively.  相似文献   
42.
After‐sales service is a major source of profit for many original equipment manufacturers in industries with durable products. Successful engagement in after‐sales service improves customer loyalty and allows for competitive differentiation through superior service like an extended service period during which customers are guaranteed to be provided with service parts. Inventory management during this period is challenging due to the substantial uncertainty concerning demand over a long time horizon. The traditional mechanism of spare parts acquisition is to place a large final order at the end of regular production of the parent product, causing major holding costs and a high level of obsolescence risk. With an increasing length of the service period, more flexibility is needed and can be provided by adding options like extra production and remanufacturing. However, coordinating all three options yields a complicated stochastic dynamic decision problem. For that problem type, we show that a quite simple decision rule with order‐up‐to levels for extra production and remanufacturing is very effective. We propose a heuristic procedure for parameter determination which accounts for the main stochastic and dynamic interactions in decision making, but still consists of relatively simple calculations that can be applied to practical problem sizes. A numerical study reveals that the heuristic performs extremely well under a wide range of conditions, and therefore can be strongly recommended as a decision support tool for the multi‐option spare parts procurement problem. A comparison with decision rules adapted from practice demonstrates that our approach offers an opportunity for major cost reductions.  相似文献   
43.
Gluing Copulas     
We present a new way of constructing n-copulas, by scaling and gluing finitely many n-copulas. Gluing for bivariate copulas produces a copula that coincides with the independence copula on some grid of horizontal and vertical sections. Examples illustrate how gluing can be applied to build complicated copulas from simple ones. Finally, we investigate the analytical as well as statistical properties of the copulas obtained by gluing, in particular, the behavior of Spearman's ρ and Kendall's τ.  相似文献   
44.
The two well-known and widely used multinomial selection procedures Bechhofor, Elmaghraby, and Morse (BEM) and all vector comparison (AVC) are critically compared in applications related to simulation optimization problems.

Two configurations of population probability distributions in which the best system has the greatest probability p i of yielding the largest value of the performance measure and has or does not have the largest expected performance measure were studied.

The numbers achieved by our simulations clearly show that none of the studied procedures outperform the other in all situations. The user must take into consideration the complexity of the simulations and the performance measure probability distribution properties when deciding which procedure to employ.

An important discovery was that the AVC does not work in populations in which the best system has the greatest probability p i of yielding the largest value of the performance measure but does not have the largest expected performance measure.  相似文献   
45.
Recent technological advances have enabled the emergence of novel business models based on digital platforms. Marketplace like Airbnb or Uber offer such digital platforms to connect previously unmatched demand-side and supply-side participants through innovative forms of value creation, delivery and capture. While countless firms claim to offer the next ‘Airbnb for X’ or ‘Uber for Y’, we lack knowledge about the defining business model characteristics of these marketplaces. To close the gap, this paper provides a conceptually and empirically grounded taxonomy of their business models. Applying a mixed methods approach, it first develops an integrative framework of marketplace business models. Guided by the framework, the research systematically analyzes 100 randomly selected marketplaces with content analysis and binary coding. The gathered data is analyzed with cluster analysis techniques to develop a taxonomy for marketplace business models. The clustering process reveals six clearly distinguishable types of marketplace business models and thus shows that there is no one-size-fits-all approach to creating, delivering, and capturing value with marketplaces and platforms in general. We characterize these distinctive types on basis of the qualitative and quantitative findings. Among others, we find that two of these types are highly aligned with business model characteristics associated with the so-called sharing economy. The findings are discussed against platform, marketplace, and sharing economy literature to contribute to a higher integration of different literature streams that are concerned with similar organizational types and phenomena.  相似文献   
46.
A Bayes linear space is a linear space of equivalence classes of proportional σ‐finite measures, including probability measures. Measures are identified with their density functions. Addition is given by Bayes' rule and substraction by Radon–Nikodym derivatives. The present contribution shows the subspace of square‐log‐integrable densities to be a Hilbert space, which can include probability and infinite measures, measures on the whole real line or discrete measures. It extends the ideas from the Hilbert space of densities on a finite support towards Hilbert spaces on general measure spaces. It is also a generalisation of the Euclidean structure of the simplex, the sample space of random compositions. In this framework, basic notions of mathematical statistics get a simple algebraic interpretation. A key tool is the centred‐log‐ratio transformation, a generalization of that used in compositional data analysis, which maps the Hilbert space of measures into a subspace of square‐integrable functions. As a consequence of this structure, distances between densities, orthonormal bases, and Fourier series representing measures become available. As an application, Fourier series of normal distributions and distances between them are derived, and an example related to grain size distributions is presented. The geometry of the sample space of random compositions, known as Aitchison geometry of the simplex, is obtained as a particular case of the Hilbert space when the measures have discrete and finite support.  相似文献   
47.
This article provides an overview of the development of a research agenda on resident-to-resident aggression (RRA) in long-term care facilities by an expert panel of researchers and practitioners. A 1-day consensus-building workshop using a modified Delphi approach was held to gain consensus on nomenclature and an operational definition for RRA, to identify RRA research priorities, and to develop a roadmap for future research on these priorities. Among the six identified terms in the literature, RRA was selected. The top five priorities were: (a) developing/assessing RRA environmental interventions; (b) identification of the environmental factors triggering RRA; (c) incidence/prevalence of RRA; (d) developing/assessing staff RRA education interventions; and (e) identification of RRA perpetrator and victim characteristics. Given the significant harm RRA poses for long-term care residents, this meeting is an important milestone, as it is the first organized effort to mobilize knowledge on this under-studied topic at the research, clinical, and policy levels.  相似文献   
48.
A rapidly expanding number of baby boomers provide care to aging parents. This study examines associations between caregiver status and outcomes related to awareness and anticipation of future long-term care (LTC) needs using 2007 Connecticut Long-Term Care Needs Assessment survey data. Baby boomers who were adult child caregivers (n = 353) versus baby boomers who were not (n = 1242) were more likely to anticipate some future LTC needs and to have considered certain financing strategies. Although baby boomer adult child caregivers more readily anticipate some future LTC needs, they are not taking specific actions. It is important to address the need for public education directed toward those who are currently (or have recently completed) caring for aging parents.  相似文献   
49.
Abstract

This essay explores a series of sovereign ‘machines’ – slaves, puppets, automata – in political theory from Benjamin to Agamben. It is now well-documented that the philosophical question of ‘the machine’ – of whether a complex system requires a human operator or whether it can function autonomously – is also a crucial political question that haunts every discussion of sovereignty from Hobbes onwards. However, my wager in what follows is that this machine is not just a metaphor for a metaphysical situation – whether it be rationality (Hobbes), bureaucratization (Weber), neutralization (Schmitt), historicism (Benjamin) or governmentality (Foucault) – but a material phenomenon that carries transformative political promise and threat. To summarize the argument of this essay, I contend that ‘sovereign machines’ like slavery (Aristotle, Hegel, Kojève, Agamben), puppets, automata or clockwork (Descartes, Hobbes, Schmitt, Benjamin, Derrida), lens, optics and mirrors (Hobbes, Kantorowicz, Benjamin, Lacan, Foucault) and so on do not merely reflect but change our understanding of the causal relationship between sovereignty and governmentality, decision and norm, exception and rule. If the self-appointed task of the modern political theorist has so often been to obtain or regain sovereignty of, or over, the machine – to jam its gears – I seek to expose what the later Derrida calls the ‘machine’ of sovereignty itself. In conclusion, I argue that political theory’s attempt to reveal or retroactively invent the sovereign person at the heart of the machine only ends up revealing the sovereign machine at the heart of the person. What – if anything – is really inside the machine of sovereignty?  相似文献   
50.

This essay takes the first Beijing Opera of China's early twentieth‐century reformist opera movement as an exemplary text and performative context through which to analyze the production of a new historical consciousness in late‐Qing China (1895–1911). Performed in Shanghai in 1904, the opera is centrally concerned with the modern partition of Poland. The essay argues that the opera's interpretation of history is a deliberate intervention into China's turbulent socio‐political atmosphere and helps mark an attempt to popularize through performance a new synchronic global consciousness that links China's contemporary history to the non‐Western world of global transformation at the turn of the twentieth century.  相似文献   
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