首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   18篇
  免费   0篇
人口学   5篇
理论方法论   2篇
综合类   3篇
社会学   5篇
统计学   3篇
  2020年   1篇
  2018年   2篇
  2016年   1篇
  2015年   1篇
  2014年   1篇
  2013年   1篇
  2010年   2篇
  2000年   1篇
  1999年   1篇
  1998年   1篇
  1992年   2篇
  1991年   1篇
  1989年   1篇
  1985年   1篇
  1984年   1篇
排序方式: 共有18条查询结果,搜索用时 0 毫秒
1.
The debate about the rise of civil society in Mexico suggests that the processes of political and economic liberalization are multiple and uneven and, thus, have different and contradictory effects on different social groups. This study takes such arguments into account and examines the nature of collective identities and social networks that are more likely to be mobilized in the rising civil society. Who, with what types of social networks and identities, are the active actors in this rising civil society in Mexico? This study also attempts to identify the central actors who take an active part in multi-sector coalitions. As such a broad coalition often leaves profound effects on politics and society, it is vital to ask which actors are likely to take an important step toward multi-sector coalition making. Using a catalog of 1797 protest campaigns collected from three Mexican newspapers between 1964 and 2000, event frequency analysis is employed to find active actors and social network analysis – blockmodel method and degree centrality measure – is applied to uncover central actors. The analyses reveal that while workers, peasants, or students continue to be very active, the centrality of these actors in contentious networks and coalitions has not increased. New central actors in the rising civil society turn out to be civic associations and NGOs formed around single issues, such as environment, retirement, and human rights. When a multi-sector coalition occurs in contemporary Mexico, NGOs and civic associations are likely to play a crucial role in it.  相似文献   
2.
Abstract

A quantitative evaluation of athletic training is one of the most important issues in the sports science, and its optimization problem between fitness and fatigue has to be considered. Although fitness is the gain of athletic training and athletes can acquire extensive fitness by hard training, they cannot continue such training for a long time because of fatigue. After the hard training which exceeds the physical capacity of athletes, a delayed onset muscle soreness (DOMS) appears and they cannot continue the same training hereafter. Because DOMS impedes the progress of training, it must be avoided when the training plan is made. By continuing training for a long period, the performance capacity of athlete body has enhanced and they can endure hard and long training with which it could not tolerate before, and such performance capacity enhancement is called supercompensation. In a planning athletic training, its optimization problem between fitness and fatigue should be discussed considering, both DOMS and supercompensation by forming probabilistic models of fitness and fatigue, optimal training plans which maximize the total fitness during training periods and minimize the occurrence of DOMS are discussed analytically and numerically.  相似文献   
3.
Summary Sibling (cannibalism among siblings) and non-sibling cannibalism (cannibalism among non-siblings) were studied in a natural population of a lady beetle,Harmonia axyridis Pallas. Of all the eggs laid (n=2269), 24.76% (n=562) were killed by sibling cannibalism and 36.10% (n=819) were killed by non-sibling cannibalism. Sibling cannibalism occurred constantly and intensively in most egg batches throughout the entire oviposition period. On the other hand, non-sibling cannibalism was more intense in the middle and late oviposition periods, and when the egg batches were close to an aphid colony. This may be due to the high density ofH. axyridis larvae relative to aphid density in the middle and late oviposition periods and also the larvae searching intensively near an aphid colony.  相似文献   
4.
Summary The adaptive significance of sibling cannibalism was analyzed in the ladybird beetleHarmonia axyridis at two prey densities. Possible costs and benefits were considered from three points of view: the mother, the cannibal and the victim. Cannibals ate both infertile and fertile eggs, thereby increasing in body length and survival rate with the intensity of sibling cannibalism. The cannibalistic trait was clearly beneficial to the cannibal when aphid density was low. However, it was not always beneficial when aphid density was high and the victims were full siblings. The altruistic behavior of being a victim was beneficial only when the victim was cannibalized by full siblings at low aphid density. The mother attained almost equal fitness at low aphid density, regardless of the intensity of sibling cannibalism. This suggests that sibling cannibalism is not maladaptive for the mother. At high aphid density, however, mother’s fitness decreased with the intensity of sibling cannibalism, indicating that sibling cannibalism is maladaptive for the mother when larval food availability is high.  相似文献   
5.
Summary There are two factors affecting long-term fluctuation of planktotrophic pelagic fish: environmental fluctuation and interspecific competition. Long-term catch data of planktotrophic pelagic fishes in Japan suggest that the chub mackerel (species B) was replaced by the sardine (A), A was replaced by the anchovy, Pacific saury and horse mackerel (Group C), and species in group C were replaced by species B. If species A defeats B, B defeats C, and C defeats A in interspecific competitive ability, then the abundance of these three groups fluctuate forever and dominate in the same order. We call this cyclic advantage hypothesis for species replacement. In this model, environmental fluctuation affects the species replacement as a trigger. Environmental fluctuation does not determine the next dominant species but greatly affects when the next replacement occurs.  相似文献   
6.
In this paper, we consider the multivariate normality test based on measure of multivariate sample skewness defined by Srivastava (1984). Srivastava derived asymptotic expectation up to the order N−1 for the multivariate sample skewness and approximate χ2χ2 test statistic, where N   is sample size. Under normality, we derive another expectation and variance for Srivastava's multivariate sample skewness in order to obtain a better test statistic. From this result, improved approximate χ2χ2 test statistic using the multivariate sample skewness is also given for assessing multivariate normality. Finally, the numerical result by Monte Carlo simulation is shown in order to evaluate accuracy of the obtained expectation, variance and improved approximate χ2χ2 test statistic. Furthermore, upper and lower percentiles of χ2χ2 test statistic derived in this paper are compared with those of χ2χ2 test statistic derived by Mardia (1974) which is used multivariate sample skewness defined by Mardia (1970).  相似文献   
7.
Housing First is a model and philosophy for housing homeless people in immediate and permanent housing. In order to implement and deliver Housing First, research is essential to understand the system of support services as they currently exist. Guided by principles of community-based participatory research, this paper presents the findings from a senior-focused deliberative dialogue workshop in Metro Vancouver, Canada. Participants (16 service providers and 1 service recipient) identified services and resources available to support seniors in maintaining housing and barriers and facilitators for accessing services. Broadly, data were organized into seven themes: (1) Housing; (2) Home support; (3) Transportation; (4) Information availability, accessibility, and navigation; (5) Cultural diversity; (6) Discrimination; and (7) Funding and financial support. Results found that affordable housing that adapts to changing health conditions, income supports, health services, homecare, transportation, and culturally appropriate and nondiscriminatory informational resources are among the supports most needed for persons as young as 50 years old to succeed under the Housing First model in Metro Vancouver. Barriers to Housing First service provision, including rigid eligibility criteria for chronically and episodically homeless, should be revised to better support the growing number of older adults who are newly entering homelessness in Metro Vancouver.  相似文献   
8.
This paper is about the analysis of paired survival data using the exponential bivariate model of Sarkar for the underlying survival times, (X,Y), subject to censoring. Under this parametric model we test parameters in the presence of covariates. We consider first, tests of hypotheses of independence and equality of survival marginals, and second, test of hypotheses of covariate effects and survival superiority of one marginal over the other are considered. For this last question we applied a statistical test based on the Union-intersection principle.  相似文献   
9.
This article provides an experimental analysis of attitude toward imprecise and variable information. Imprecise information is provided in the form of a set of possible probability values, such that it is virtually impossible for the subjects to guess or estimate, which one in the set is true or more likely to be true. We investigate how geometric features of such information pieces affect choices. We find that the subjects care about more features than the pairs of best-case and worst-case, which is a counter-evidence to the well-known models, maximin and α-maximin. We find that presence of nonextreme points in the set affects choice, which suggests that attitude toward imprecision is ‘nonlinear.’ We also obtain an observation, though not significant, that information pieces have a complementarity that may not be explained by the Bayesian view.  相似文献   
10.
Summary It is well known that the stock abundance of a pelagic fish usually fluctuates and a species of pelagic fish which was dominant in abundance is often taken over by another species. Several alternative models for species replacement among pelagic fishes are presented and analyzed: (A) environmental fluctuation, (B) strong density-dependent reproduction rate, (C) a two-species system with phase variation (density-dependent change of life history traits), (D) a two-species competition system with environmental fluctuation, (E) cyclic advantage relationship among three competitive species, and (F) a two-prey, one-predator system. Different model requires different number of species for the occurrence of species replacement. Three criteria to test each hypothesis from qualitative properties of species replacement are proposed. Possible management policies to decrease the amplitude of stock fluctuations are discussed. As a result, if the catching effort to mackerels which is rare now is large, or if the catching effort to the sardine is still large when it begins to decline in stock abundance, fisheries may be strong destabilizing effect on the stock abundance.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号