全文获取类型
收费全文 | 5347篇 |
免费 | 241篇 |
国内免费 | 8篇 |
学科分类
社会科学 | 5596篇 |
出版年
2024年 | 7篇 |
2023年 | 73篇 |
2022年 | 74篇 |
2021年 | 105篇 |
2020年 | 207篇 |
2019年 | 263篇 |
2018年 | 364篇 |
2017年 | 379篇 |
2016年 | 301篇 |
2015年 | 176篇 |
2014年 | 271篇 |
2013年 | 783篇 |
2012年 | 481篇 |
2011年 | 231篇 |
2010年 | 195篇 |
2009年 | 186篇 |
2008年 | 172篇 |
2007年 | 150篇 |
2006年 | 117篇 |
2005年 | 111篇 |
2004年 | 161篇 |
2003年 | 133篇 |
2002年 | 123篇 |
2001年 | 89篇 |
2000年 | 69篇 |
1999年 | 33篇 |
1998年 | 42篇 |
1997年 | 26篇 |
1996年 | 33篇 |
1995年 | 21篇 |
1994年 | 18篇 |
1993年 | 14篇 |
1992年 | 22篇 |
1991年 | 14篇 |
1990年 | 14篇 |
1989年 | 17篇 |
1988年 | 9篇 |
1987年 | 15篇 |
1985年 | 9篇 |
1984年 | 9篇 |
1983年 | 6篇 |
1982年 | 6篇 |
1981年 | 7篇 |
1980年 | 10篇 |
1979年 | 5篇 |
1978年 | 6篇 |
1974年 | 5篇 |
1973年 | 3篇 |
1971年 | 4篇 |
1968年 | 4篇 |
排序方式: 共有5596条查询结果,搜索用时 15 毫秒
1.
Dennis Wagenaar Tiaravanni Hermawan Marc J. C. van den Homberg Jeroen C. J. H. Aerts Heidi Kreibich Hans de Moel Laurens M. Bouwer 《Risk analysis》2021,41(1):37-55
Damage models for natural hazards are used for decision making on reducing and transferring risk. The damage estimates from these models depend on many variables and their complex sometimes nonlinear relationships with the damage. In recent years, data‐driven modeling techniques have been used to capture those relationships. The available data to build such models are often limited. Therefore, in practice it is usually necessary to transfer models to a different context. In this article, we show that this implies the samples used to build the model are often not fully representative for the situation where they need to be applied on, which leads to a “sample selection bias.” In this article, we enhance data‐driven damage models by applying methods, not previously applied to damage modeling, to correct for this bias before the machine learning (ML) models are trained. We demonstrate this with case studies on flooding in Europe, and typhoon wind damage in the Philippines. Two sample selection bias correction methods from the ML literature are applied and one of these methods is also adjusted to our problem. These three methods are combined with stochastic generation of synthetic damage data. We demonstrate that for both case studies, the sample selection bias correction techniques reduce model errors, especially for the mean bias error this reduction can be larger than 30%. The novel combination with stochastic data generation seems to enhance these techniques. This shows that sample selection bias correction methods are beneficial for damage model transfer. 相似文献
2.
It is uncertain whether Latin America and Caribbean (LAC) countries are approaching a single mortality regime. Over the last three decades, LAC has experienced major public health interventions and the highest number of homicides in the world. However, these interventions and homicide rates are not evenly shared across countries. This study documents trends in life expectancy and lifespan variability for 20 LAC countries, 2000–14. By extending a previous method, we decompose differences in lifespan variability between LAC and a developed world benchmark into cause-specific effects. For both sexes, dispersion of amenable diseases through the age span makes the largest contribution to the gap between LAC and the benchmark. Additionally, for males, the concentration of homicides, accidents, and suicides in mid-life further impedes mortality convergence. Great disparity exists in the region: while some countries are rapidly approaching the developed regime, others remain far behind and suffer a clear disadvantage in population health. 相似文献
3.
Nuria Infante-Torres Milagros Molina-Alarcón Ana Rubio-Álvarez Julián Rodríguez-Almagro Antonio Hernández-Martínez 《Women and birth : journal of the Australian College of Midwives》2018,31(5):e318-e324
Aim
To assess the relationship between the duration of the second stage of labour and postpartum anaemia during vaginal birth.Methods
An observational, analytical retrospective cohort study was performed at the “Mancha-Centro Hospital” (Spain) during the 2013–2016 period. Data were collected from 3437 women who had a vaginal birth. Postpartum anaemia was defined as a haemoglobin level below 11 g/dL at 24 h postpartum. A univariate analysis was used for potential risk factors and a multivariate analysis with binary logistic regression to control for possible confounding factors.Findings
The incidence of postpartum anaemia was 42.0%. The risk of postpartum anaemia did not increase in nulliparous women whose duration of the second stage of labour exceeded 4 h. Compared with multiparous women who delivered between 0 and 3 h, multiparous women with a duration of the second stage of labour beyond 3 h were at higher risk of postpartum anaemia (OR = 2.43 [1.30–4.52]).Conclusion
The duration of the second stage of labour beyond 4 h is safe for postpartum anaemia in nulliparous women. However in multiparous women, monitoring should increase if the second stage of labour exceeds 3 h given the increased risk of postpartum anaemia. 相似文献4.
5.
Mark A. van de Wiel Dennis E. Te Beest Magnus M. Münch 《Scandinavian Journal of Statistics》2019,46(1):2-25
Empirical Bayes is a versatile approach to “learn from a lot” in two ways: first, from a large number of variables and, second, from a potentially large amount of prior information, for example, stored in public repositories. We review applications of a variety of empirical Bayes methods to several well‐known model‐based prediction methods, including penalized regression, linear discriminant analysis, and Bayesian models with sparse or dense priors. We discuss “formal” empirical Bayes methods that maximize the marginal likelihood but also more informal approaches based on other data summaries. We contrast empirical Bayes to cross‐validation and full Bayes and discuss hybrid approaches. To study the relation between the quality of an empirical Bayes estimator and p, the number of variables, we consider a simple empirical Bayes estimator in a linear model setting. We argue that empirical Bayes is particularly useful when the prior contains multiple parameters, which model a priori information on variables termed “co‐data”. In particular, we present two novel examples that allow for co‐data: first, a Bayesian spike‐and‐slab setting that facilitates inclusion of multiple co‐data sources and types and, second, a hybrid empirical Bayes–full Bayes ridge regression approach for estimation of the posterior predictive interval. 相似文献
6.
Open innovation and absorptive capacity are two concepts based on the idea that companies can leverage the knowledge generated externally to improve their innovation performance. The aim of this paper is to analyse the joint effect of open innovation and absorptive capacity on a firm's radical innovation. Open innovation is expressed in terms of external search breadth and depth strategies and absorptive capacity is described by distinguishing between potential and realized absorptive capacity. In order to test our hypotheses, we carried out empirical research in firms operating in high-technology industries. The results indicate that internal routines and processes for absorbing external knowledge help explain radical innovation as they show a significant effect of potential and realized absorptive capacity. Also, there is a moderating effect of absorptive capacity on open innovation. Specifically, potential absorptive capacity exerts a positive effect on the relationship between external search breadth and depth and radical innovation. Realized absorptive capacity moderates the influence of external search breadth. These findings confirm the complementary nature of absorptive capacity and open innovation search strategies on radical innovation. 相似文献
7.
de Jong Petra W. Caarls Kim de Valk Helga A. G. 《Population research and policy review》2022,41(2):671-694
Population Research and Policy Review - The welfare state can be perceived as a safety net which helps individuals adjust to situations of risk or transition. Starting from this idea of the welfare... 相似文献
8.
Serra Sónia R. Q. Calapez Ana Raquel Simões Nuno Eduardo Sá Marques José A. A. Laranjo Maria Feio Maria João 《Urban Ecosystems》2019,22(6):1173-1186
Urban Ecosystems - Urban streams provide important ecosystem services to cities’ population, from the maintenance of urban biodiversity, temperature, humidity and air quality to improving... 相似文献
9.
Luis Villar-Fidalgo María del Mar Espinosa Escudero Manuel Domínguez Somonte 《生产规划与管理》2019,30(8):624-638
Not only ETO (Engineering to Order), but even serial production industry should know how to deal with projects and their schedule: plant commissioning, shutdown, introducing new products and similar circumstances should be managed with adequate planning and resource allocation techniques to create a schedule useful in decision making during the execution. The current complex reality, with evolving technologies and fierce pressure to reach the market as soon as possible, pushes the project managers to use more advanced techniques than waterfall planning, such as agile or lean. It also requires them to take a holistic view and manage concurrent tasks in complex projects. The contributions of this paper are two: the proposal to control specific parallel groups of waterfall activities under uncertain environments, which can lead to iterations and reworks, as a single concurrent Activity Managed by Kanban Methods (AMKM). This activity can be subsequently embedded into traditional scheduling approaches as CPM-PERT. The second contribution is the feasibility of its application in industrial environments due to the affordability of simulation software. Two use cases are shown as evidence. It is not a disruptive proposal, but a kaizen action based on very mature technologies. Finally, it is suggested some improvements to be implemented in Project Management Software due to this ‘kaizen’ proposal. 相似文献
10.
Social Indicators Research - Monitoring progress towards the Sustainable Development Goals by 2030 requires the global community to disaggregate targets along socio-economic lines, but little has... 相似文献