全文获取类型
收费全文 | 2410篇 |
免费 | 67篇 |
国内免费 | 19篇 |
专业分类
管理学 | 120篇 |
民族学 | 20篇 |
人才学 | 2篇 |
人口学 | 91篇 |
丛书文集 | 190篇 |
理论方法论 | 140篇 |
综合类 | 1254篇 |
社会学 | 596篇 |
统计学 | 83篇 |
出版年
2024年 | 9篇 |
2023年 | 23篇 |
2022年 | 25篇 |
2021年 | 20篇 |
2020年 | 67篇 |
2019年 | 44篇 |
2018年 | 68篇 |
2017年 | 90篇 |
2016年 | 49篇 |
2015年 | 65篇 |
2014年 | 99篇 |
2013年 | 372篇 |
2012年 | 116篇 |
2011年 | 105篇 |
2010年 | 99篇 |
2009年 | 108篇 |
2008年 | 126篇 |
2007年 | 139篇 |
2006年 | 125篇 |
2005年 | 118篇 |
2004年 | 106篇 |
2003年 | 104篇 |
2002年 | 105篇 |
2001年 | 99篇 |
2000年 | 44篇 |
1999年 | 34篇 |
1998年 | 22篇 |
1997年 | 15篇 |
1996年 | 19篇 |
1995年 | 4篇 |
1994年 | 15篇 |
1993年 | 9篇 |
1992年 | 13篇 |
1991年 | 7篇 |
1990年 | 7篇 |
1989年 | 5篇 |
1988年 | 3篇 |
1987年 | 3篇 |
1986年 | 4篇 |
1985年 | 4篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1980年 | 1篇 |
排序方式: 共有2496条查询结果,搜索用时 0 毫秒
41.
Dorin Drignei 《统计学通讯:模拟与计算》2016,45(9):3281-3293
Computer models with functional output are omnipresent throughout science and engineering. Most often the computer model is treated as a black-box and information about the underlying mathematical model is not exploited in statistical analyses. Consequently, general-purpose bases such as wavelets are typically used to describe the main characteristics of the functional output. In this article we advocate for using information about the underlying mathematical model in order to choose a better basis for the functional output. To validate this choice, a simulation study is presented in the context of uncertainty analysis for a computer model from inverse Sturm-Liouville problems. 相似文献
42.
Lyn Craig 《Journal of Family and Economic Issues》2007,28(1):69-87
Time use studies find that employed mothers reduce their parental childcare time by much less than an hour for every hour
they spend in market work. This paper uses data from the Australian Bureau of Statistics Time Use Survey 1997 (4,059 randomly selected households) to investigate how employed mothers manage to avoid a one-for-one trade-off between
work and childcare. It compares the time allocation of employed fathers, employed mothers and non-employed mothers and finds
that parents use non-parental childcare to reschedule as well as to replace their own childcare, that employed mothers reschedule
activities from weekdays to weekends or to earlier or later in the day, and spend less time than other mothers in housework,
childfree leisure and personal care.
相似文献
Lyn CraigEmail: |
43.
Assessing the effects of land use and land cover patterns on thermal conditions using landscape metrics in city of Indianapolis,United States 总被引:6,自引:0,他引:6
Direct applications of remote sensing thermal infrared (TIR) data in landscape ecological research are rare due to limitations
in the sensors, calibration, and difficulty in interpretation. Currently there is a general lack of methodology for examining
the relationship between land surface temperatures (LST) derived from TIR data and landscape patterns extracted from optical
sensors. A separation of landscapes into values directly related to their scale and signature is a key step. In this study,
a Landsat ETM+ image of Indianapolis, Unites States, acquired on June 22, 2000, was spectrally unmixed (using spectral mixture
analysis, SMA) into fraction endmembers of green vegetation, soil, high albedo, and low albedo. Impervious surface was then
computed from the high and low albedo images. A hybrid classification procedure was developed to classify the fraction images
into seven land use and land cover (LULC) classes. Using the fractional images, the landscape composition and pattern were
examined. Next, pixel-based LST measurements were correlated with the landscape fractional components to investigate LULC
based relationships between LST and impervious surface and green vegetation fractions. An examination of the relationship
between the LULC and LST maps with landscape metrics was finally conducted to deepen understanding of their interactions.
Results indicate that SMA-derived fraction images were effective for quantifying the urban morphology and for providing reliable
measurements of biophysical variables. LST was found to be positively correlated with impervious surface fraction but negatively
correlated with green vegetation fraction. Each temperature zone was associated with a dominant LULC category. Further research
should be directed to the theoretical and applied implications of describing such relationships between LULC patterns and
urban thermal conditions.
相似文献
Dengsheng LuEmail: |
44.
A knowledge-based system supporting managerial problem diagnosis is described. The system provides the capability to monitor values of selected variables for problem situations. When problems are located, a list of problem symptoms is delivered to a problem processor for structuring and diagnosis. Problem structuring is based on a combination of concepts from expert systems and structural modeling. User assertions about cause-effect relationships between pairs of variables are maintained in a semantic network. Problem diagnosis uses the relationships in the semantic network to construct causation trees, the branches of which represent potential explanations of the problem symptoms. Mathematical models are constructed based on causation-tree branches, and values from the data base are used to test whether the model confirms the diagnosis. If so, the source of the problem has been located and it is then up to the user to resolve the problem. If the model fails to explain the problem, the model apparently is deficient and the user may perform “what if…” type scenarios in attempts to improve the model and search for problem causes. Realistic applications in the accounting and health care areas are discussed. 相似文献
45.
随着科学技术的迅猛发展以及国际交流的日益加深,加之互联网的促动,当代汉语与外语特别是英语的接触进入了前所未有的深广阶段。当代汉语中出现了大量的字母词。字母词是一个原型概念,根据字母词的概念原型,求证出字母词的4个形式指标,由此我们可以得出字母词的15种基本形式。外文原词不具有字母词的任何形式指标,不是字母词。六百万字样本语料库共出现字母词6068词次;平均每种报纸每天出现144.48词次字母词。新闻语体中字母词的平均使用密度为0.711。科技领域的使用密度最高,其次是教育领域;再次是经济领域,军事领域和政法领域使用密度最低。字母词的使用密度和文章领域相关,和地域及报纸性质不相关。 相似文献
46.
Decision analysis tools often are used in semistructured and ill-structured situations. While some researchers have argued that computerized decision analysis programs may improve decision quality in such situations, research support for this assertion is weak. In this laboratory study, business students used a computerized decision-analysis program with short strategic-management cases to prepare decision reports. Independent raters' perceptions of aided and unaided decision performance were contrasted, attitudes of students toward the program were assessed, individual differences were correlated with attitudes, and the program's impact on students' perceptions of their decision processes and performance was examined. Student attitudes toward the computerized aid were favorable, and individual differences in reactions generally were as predicted. However, the program did not improve the independent ratings of students' decision reports and recommendations. These findings suggest that computerized decision aids should be adopted cautiously. If such aids result in positive user affect and heightened decision confidence without corresponding improvements in decision quality, they may be dysfunctional. Rigorous research methodologies which incorporate independent evaluations of analyses and decisions are recommended for use in future research on computerized decision-analysis programs. 相似文献
47.
试论劳动价值与效用价值的数量关系 总被引:1,自引:0,他引:1
邓宏 《广州大学学报(社会科学版)》2007,6(4):52-56
劳动价值论和效用价值论是关于价值决定的两个最具代表性的理论,一般认为二者是互不相容的。文章从不易产生歧义的“使用价值”概念出发,把自然界和人类劳动对价值的贡献区别开来,进一步澄清了价值相关概念,并发现劳动价值与人工效用在数量上总是相等的。如果把劳动价值论和效用价值论融合起来,价值决定理论可能更为完整。 相似文献
48.
This study examined the characteristics of youth with different types of purpose in life, as well as the associations between adolescents’ life satisfaction, purpose in life, meaning in life, social support, and problematic digital use. The sample included 193 participants aged 14–18 who completed self-report questionnaires on life satisfaction, purpose in life, meaning in life, social support, and problematic digital use. The following purpose in life clusters were found: (1) other-oriented goals (n?=?33); (2) self-oriented goals (n?=?42); and (3) both other- and self-oriented goals (n?=?107). Adolescents with both self- and other-oriented goals had significantly higher life satisfaction, meaning in life, and social support compared to the other groups. Meaning in life and greater support from parents and teachers were significantly associated with greater life satisfaction. In addition, having other-oriented goals was associated with lower life satisfaction. Finally, support from parents (p?=?0.05) mediated the association between problematic digital use and life satisfaction. Findings are discussed in light of previous research and the theoretical and practical implications are examined. 相似文献
49.
Multisite evaluation has been cited as a strategy for building knowledge about a program's success and enhancing evaluation capacity and evaluation use. Even so, the extent to which data from these efforts are made available to individual project participants varies. This article describes a community-created multisite evaluation that was designed to overcome this limitation. Based on the negotiated centralized evaluation model and implemented within the context of a community of practice, the EvalFest community-created multisite evaluation has used shared measures to collect data from 30,000 participants from partner sites across the community over three years. This article describes the design characteristics of the community-created multisite approach, and presents results related to partners’ evaluation use that demonstrate the early success of this method. We conclude by considering how this strategy might be applied to other sectors. 相似文献
50.
Jennifer M. Cadigan Emily R. Dworkin Jason J. Ramirez Christine M. Lee 《Journal of American college health : J of ACH》2019,67(4):383-390
Objective: The objective of this study was to understand substance use patterns of alcohol, marijuana, and simultaneous alcohol and marijuana (SAM) use among 2- and 4-year college students. Participants: Participants were 526 young adults aged 18–23 (n?=?355 4-year students; n?=?171 2-year students) recruited from February 2015 to January 2016 who were participating in a larger longitudinal study. Methods: Latent class analysis (LCA) was used to identify past-month classes of alcohol, marijuana, and SAM use. Results: Among both 2- and 4-year students, a four-class solution yielded the best-fitting model, with 2-year classes tending to include greater marijuana use and less alcohol use and 4-year classes tending to include heavy alcohol use. Demographic characteristics were largely similar across classes. Conclusions: Classes of alcohol, marijuana, and SAM use differed by education status. Screening and prevention efforts for 4-year students may need to be tailored for the needs of 2-year students. 相似文献