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   735篇
  免费   28篇
管理学   120篇
民族学   4篇
人口学   73篇
理论方法论   71篇
综合类   3篇
社会学   312篇
统计学   180篇
  2024年   2篇
  2023年   6篇
  2022年   9篇
  2021年   9篇
  2020年   34篇
  2019年   40篇
  2018年   45篇
  2017年   44篇
  2016年   35篇
  2015年   24篇
  2014年   42篇
  2013年   130篇
  2012年   59篇
  2011年   37篇
  2010年   28篇
  2009年   27篇
  2008年   18篇
  2007年   20篇
  2006年   24篇
  2005年   13篇
  2004年   10篇
  2003年   11篇
  2002年   13篇
  2001年   10篇
  2000年   9篇
  1999年   5篇
  1998年   6篇
  1997年   4篇
  1996年   3篇
  1995年   3篇
  1994年   5篇
  1993年   4篇
  1992年   7篇
  1991年   4篇
  1990年   2篇
  1989年   1篇
  1988年   2篇
  1987年   2篇
  1986年   2篇
  1985年   1篇
  1984年   2篇
  1983年   2篇
  1982年   2篇
  1979年   3篇
  1973年   1篇
  1968年   2篇
  1967年   1篇
排序方式: 共有763条查询结果,搜索用时 15 毫秒
61.
Elderly patients with cardiovascular events are characterized by high drug consumptions. Whether high drug consumptions are related to physical activity is not known. In order to examine whether physical activity is related to drug consumption in the elderly, patients older than 65 years (n?=?250) with a recent cardiovascular event were studied. Physical activity was analyzed according to the Physical Activity Scale for the Elderly (PASE) score and related to drug consumption. PASE score was 72.4?±?45.0 and drug consumption was 8.3?±?2.2. Elderly patients with greater comorbidity took more drugs (8.7?±?2.1) and are less active (PASE?=?64.4?±?50.6) than patients with Cumulative Illness Rating Scale severity score higher than 1.8 than those with a score lower than 1.8 (76.3?±?41.4, p?<?0.05, and 8.0?±?2.0, p?=?0.006, respectively). Multivariate analysis correlation confirmed that PASE score is negatively associated with drug consumption (β?=??0.149, p?=?0.031), independently of several variables including comorbidity. Thus, physical activity is inversely related to drug consumption in elderly patients with cardiovascular events. This inverse relationship may be attributable to the high degree of comorbidity observed in elderly patients in whom poor level of physical activity and high drug consumption are predominant.  相似文献   
62.
Susan Migden Socolow, The Bureaucrats of Buenos Aires, 1769–1810: Amor al Real Servicio (1987), xxi + 356 (Duke University Press, Durham, N.C., $45.00).

W. Hamish Fraser, Conflict and Class. Scottish Workers 1700–1838 (1988), 202 (John Donald, £20.00).

Margaret Ripley Wolfe, Kingsport, Tennessee: A Planned American City (1987), xii + 259 (The University Press of Kentucky, Lexington, £24.00).

Carl Chinn, They Worked All Their Lives. Women of the Urban Poor in England, 1880–1939 (1988), xii + 187 (Manchester University Press, Manchester, £22.50).

Linda Bryder, Below the Magic Mountain: A Social History of Tuberculosis in Twentieth‐Century Britain (1988), xv + 298 (Oxford University Press, Oxford, £30.00).

F. B. Smith, The Retreat of Tuberculosis 1850–1950 (1988), 271 (Croom Helm, £25.00).  相似文献   
63.
This paper extends the scedasticity comparison among several groups of observations, usually complying with the homoscedastic and the heteroscedastic cases, in order to deal with data sets laying in an intermediate situation. As is well known, homoscedasticity corresponds to equality in orientation, shape and size of the group scatters. Here our attention is focused on two weaker requirements: scatters with the same orientation, but with different shape and size, or scatters with the same shape and size but different orientation. We introduce a multiple testing procedure that takes into account each of the above conditions. This approach discloses a richer information on the data underlying structure than the classical method only based on homo/heteroscedasticity. At the same time, it allows a more parsimonious parametrization, whenever the patterned model is appropriate to describe the real data. The new inferential methodology is then applied to some well-known data sets, chosen in the multivariate literature, to show the real gain in using this more informative approach. Finally, a wide simulation study illustrates and compares the performance of the proposal using data sets with gradual departure from homoscedasticity.  相似文献   
64.
Risk Perception in a Developing Country: The Case of Chile   总被引:2,自引:0,他引:2  
In this work we characterize risk perception in Chile, based on the psychometric paradigm, exploring the difference between perceived social and personal risk. For this purpose, we conducted a survey including 54 hazards, 16 risk attributes, and 3 risk constructs. The survey, divided into four parts, was administered to 508 residents of Santiago, Chile. Using factor analysis, three main factors, which accounted for 80% of the sample's variance, were identified: factor 1, commonly called "Dread Risk" in the literature, explained 37% of variance; factor 2, "Unknown Risk," explained 28%; and factor 3, which we called "Personal Effect," explained 15% of the variance. On average, individuals perceived themselves as less exposed to risk and with more control and knowledge about them than the general population. OLS regression models were used to test the association of perceived risk with the three main factors. For social risk, factor 1 had the greatest explanatory power, while factor 2 had a negative sign. For personal risk, only factors 2 and 3 were significant, with factor 3 having the greatest explanatory power. Risk denial (defined as the difference between perceived personal and social risk) was associated with factors 1 and 2 only, with factor 2 having a negative sign. The difference between desired and actual regulation levels proved positive for all hazards, thus indicating that Chileans are dissatisfied with the current regulation level for all the hazards analyzed. The comparison of data at the aggregate and at the individual subject's level suggests that while the aggregate analysis overestimates the magnitude of the correlations it still reflects the tendency of the individual responses.  相似文献   
65.
This paper investigates the political framing of population in policy discourse through an analysis of legislative documents. Semantic network analysis was conducted and results were interpreted through discourse analysis of the typical arguments identified. Policy texts were classified into three sets: population management, reproductive health and family planning, and anti-abortion and anti-FP. While the “population management” frame focuses on social and economic consequences of population growth, the “reproductive health” frame defines the problem from a health perspective. Both policies propose aggressive FP programs but each frame uses distinct political rhetoric and semantic approach in its arguments. The “anti-abortion and anti-FP” frame identifies two problems: rise in incidence of abortion and existing policy that prohibit health professionals from refusing patients information on contraception. By invoking a moral argument and anchoring on rights, these policies challenge the problem and solutions identified by the first two frames.  相似文献   
66.
The main models of machine learning are briefly reviewed and considered for building a classifier to identify the Fragile X Syndrome (FXS). We have analyzed 172 patients potentially affected by FXS in Andalusia (Spain) and, by means of a DNA test, each member of the data set is known to belong to one of two classes: affected, not affected. The whole predictor set, formed by 40 variables, and a reduced set with only nine predictors significantly associated with the response are considered. Four alternative base classification models have been investigated: logistic regression, classification trees, multilayer perceptron and support vector machines. For both predictor sets, the best accuracy, considering both the mean and the standard deviation of the test error rate, is achieved by the support vector machines, confirming the increasing importance of this learning algorithm. Three ensemble methods - bagging, random forests and boosting - were also considered, amongst which the bagged versions of support vector machines stand out, especially when they are constructed with the reduced set of predictor variables. The analysis of the sensitivity, the specificity and the area under the ROC curve agrees with the main conclusions extracted from the accuracy results. All of these models can be fitted by free R programs.  相似文献   
67.
68.
The paper defines a measure on the set of stable matchings in the marriage problem. This measure is based on the minimization of the envy difference between the sets of men and women, while preserving stability and selects stable matchings with the least conflict of interest between both groups of agents. The solution concept proposed is called Sex-equal Matching (SEM) and the paper also provides an algorithm to compute the set of SEM.  相似文献   
69.
In analogy with the cumulative residual entropy recently proposed by Wang et al. [2003a. A new and robust information theoretic measure and its application to image alignment. In: Information Processing in Medical Imaging. Lecture Notes in Computer Science, vol. 2732, Springer, Heidelberg, pp. 388–400; 2003b. Cumulative residual entropy, a new measure of information and its application to image alignment. In: Proceedings on the Ninth IEEE International Conference on Computer Vision (ICCV’03), vol. 1, IEEE Computer Society Press, Silver Spring, MD, pp. 548–553], we introduce and study the cumulative entropy, which is a new measure of information alternative to the classical differential entropy. We show that the cumulative entropy of a random lifetime X can be expressed as the expectation of its mean inactivity time evaluated at X. Hence, our measure is particularly suitable to describe the information in problems related to ageing properties of reliability theory based on the past and on the inactivity times. Our results include various bounds to the cumulative entropy, its connection to the proportional reversed hazards model, and the study of its dynamic version that is shown to be increasing if the mean inactivity time is increasing. The empirical cumulative entropy is finally proposed to estimate the new information measure.  相似文献   
70.
Population and Deforestation in Costa Rica   总被引:5,自引:0,他引:5  
This paper addresses a central debate in research and policy on population and environment, namely the extent to which rapid population growth is associated with the massive deforestation currently underway in the tropics. We utilize the experience of Costa Rica during the last forty years to illustrate what the main issues are, discuss the history of deforestation in that country, and present results from conventional regression methods and from the application of spatial analyses. These analyses enable us to estimate the magnitude of the relation between population and deforestation and to identify the factors that are responsible for the linkage between them.  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