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11.
In confirmatory clinical trials, the prespecification of the primary analysis model is a universally accepted scientific principle to allow strict control of the type I error. Consequently, both the ICH E9 guideline and the European Medicines Agency (EMA) guideline on missing data in confirmatory clinical trials require that the primary analysis model is defined unambiguously. This requirement applies to mixed models for longitudinal data handling missing data implicitly. To evaluate the compliance with the EMA guideline, we evaluated the model specifications in those clinical study protocols from development phases II and III submitted between 2015 and 2018 to the Ethics Committee at Hannover Medical School under the German Medicinal Products Act, which planned to use a mixed model for longitudinal data in the confirmatory testing strategy. Overall, 39 trials from different types of sponsors and a wide range of therapeutic areas were evaluated. While nearly all protocols specify the fixed and random effects of the analysis model (95%), only 77% give the structure of the covariance matrix used for modeling the repeated measurements. Moreover, the testing method (36%), the estimation method (28%), the computation method (3%), and the fallback strategy (18%) are given by less than half the study protocols. Subgroup analyses indicate that these findings are universal and not specific to clinical trial phases or size of company. Altogether, our results show that guideline compliance is to various degrees poor and consequently, strict type I error rate control at the intended level is not guaranteed.  相似文献   
12.
Searches for faint signals in counting experiments are often encountered in particle physics and astrophysics, as well as in other fields. Many problems can be reduced to the case of a model with independent and Poisson-distributed signal and background. Often several background contributions are present at the same time, possibly correlated. We provide the analytic solution of the statistical inference problem of estimating the signal in the presence of multiple backgrounds, in the framework of objective Bayes statistics. The model can be written in the form of a product of a single Poisson distribution with a multinomial distribution. The first is related to the total number of events, whereas the latter describes the fraction of events coming from each individual source. Correlations among different backgrounds can be included in the inference problem by a suitable choice of the priors.  相似文献   
13.
We present tight upper and lower bounds for the traveling salesman path through the points of two-dimensional modular lattices. We use these results to bound the traveling salesman path of two-dimensional Kronecker point sets. Our results rely on earlier work on shortest vectors in lattices as well as on the strong convergence of Jacobi–Perron type algorithms.  相似文献   
14.
Graffiti is an illegitimate culture, yet with high potential for distinction and abstract aesthetic principles. The article considers these characteristics as result of the process of the autonomization of graffiti as subcultural field and aims to reconstruct its field logic.  相似文献   
15.
    
We consider social welfare functions that satisfy Arrow's classic axioms of independence of irrelevant alternatives and Pareto optimality when the outcome space is the convex hull of some finite set of alternatives. Individual and collective preferences are assumed to be continuous and convex, which guarantees the existence of maximal elements and the consistency of choice functions that return these elements, even without insisting on transitivity. We provide characterizations of both the domains of preferences and the social welfare functions that allow for anonymous Arrovian aggregation. The domains admit arbitrary preferences over alternatives, which completely determine an agent's preferences over all mixed outcomes. On these domains, Arrow's impossibility turns into a complete characterization of a unique social welfare function, which can be readily applied in settings involving divisible resources such as probability, time, or money.  相似文献   
16.
    
Two fundamental axioms in social choice theory are consistency with respect to a variable electorate and consistency with respect to components of similar alternatives. In the context of traditional non‐probabilistic social choice, these axioms are incompatible with each other. We show that in the context of probabilistic social choice, these axioms uniquely characterize a function proposed by Fishburn (1984). Fishburn's function returns so‐called maximal lotteries, that is, lotteries that correspond to optimal mixed strategies in the symmetric zero‐sum game induced by the pairwise majority margins. Maximal lotteries are guaranteed to exist due to von Neumann's Minimax Theorem, are almost always unique, and can be efficiently computed using linear programming.  相似文献   
17.
Many franchise-based retail outlets offer both the franchisor-owned brand and brands of competitors or independent suppliers. As salespeople may influence customers’ brand choices considerably, an important concern for franchisors is how to raise salespeople’s selling preferences for the franchisor-owned brand. However, the channel administration literature suggests that salespeople may not automatically favor the franchisor’s brand over other brand lines. While a large body of research examines franchise–channel relationships, previous investigations have conspicuously overlooked this channel conflict. In proposing a conceptual model grounded in the behavioral sciences, this study analyzes how franchisors can induce salespeople to advocate their brand by fostering the intention to promote the franchisor-owned brand (IFOB) in customer interaction. The results of an empirical field study show that individual brand promotion depends on factors such as salespeople’s identification with the franchisor and their tenure with the organization, as well as on the franchisor’s prestige and administration of the franchise. Moreover, we find that franchisees’ IFOB transfers to salespeople, but only if franchisees display a charismatic leadership style. We discuss these findings in light of extant theory and empirical evidence and derive several managerially relevant implications for the administration of franchised retail channels.  相似文献   
18.
Abstract. This paper investigates the effects of using dismissal taxes to finance unemployment benefits. We compare dismissal and employment taxes in a model with search frictions. Employment taxes give rise to externalities because firms do not take into account the effects their dismissal decisions have on others. These externalities can be tackled by using dismissal taxes to finance unemployment insurance. Taking into account the budget for unemployment insurance, employment taxes can be reduced by more than is necessary to offset the adverse effect of dismissal taxes on the value of the firm. The introduction of dismissal taxes leads to higher job creation and lower unemployment.  相似文献   
19.
How do firm-specific, demand-related factors influence the relationship between intra-industry diversification (IID) and performance? Recent findings regarding the performance effects of IID depict a complex picture with curvilinear relationships and several contingencies. However, firm-specific contingencies on the demand side have remained unexplored. We analyze how IID relates to firm performance (market share) in the German automotive industry using panel data between 1999 and 2008. We specifically focus on a firm's high-quality brand image as a demand-side contingency. We find support for our hypotheses of complex curvilinear relationships as well as for moderating effects of brand quality. Our results have significant theoretical implications for the IID literature.  相似文献   
20.
    
Relations between society and business are increasingly characterized by the societal demand for compliance with ethical standards. Companies are held responsible for behavior of their employees, which increases the demand for effective internal governance. To assure compliance, many companies enact codes of ethics. Despite a common core of ethical standards, codes differ considerably in formal design elements. Albeit theory suggests that a code's formal design, that is, how a code's content is presented, affects its behavioral impact, there is little research on this issue. Addressing this research gap, we conducted a between-subjects experiment (factorial survey) in which we manipulated design elements of codes and examined how these elements affect behavioral intentions in various business situations. Holding the code's content constant, we manipulated its tone (positive vs. negative) and whether it was signed by the company's executive board (with vs. without signature). Our results indicate that the effectiveness of a code can be improved by using signed codes, while there is no effect for a code's tone. Our paper contributes designing internal governance in two ways: by giving experimental evidence on the relevance of a code's formal design and by providing practical guidance how to increase code effectiveness.  相似文献   
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