全文获取类型
收费全文 | 24560篇 |
免费 | 722篇 |
国内免费 | 4篇 |
专业分类
管理学 | 3623篇 |
民族学 | 120篇 |
人才学 | 10篇 |
人口学 | 2307篇 |
丛书文集 | 112篇 |
教育普及 | 2篇 |
理论方法论 | 2409篇 |
现状及发展 | 1篇 |
综合类 | 305篇 |
社会学 | 12190篇 |
统计学 | 4207篇 |
出版年
2023年 | 117篇 |
2021年 | 151篇 |
2020年 | 368篇 |
2019年 | 526篇 |
2018年 | 615篇 |
2017年 | 773篇 |
2016年 | 652篇 |
2015年 | 474篇 |
2014年 | 600篇 |
2013年 | 3870篇 |
2012年 | 813篇 |
2011年 | 813篇 |
2010年 | 599篇 |
2009年 | 505篇 |
2008年 | 609篇 |
2007年 | 651篇 |
2006年 | 630篇 |
2005年 | 631篇 |
2004年 | 562篇 |
2003年 | 522篇 |
2002年 | 567篇 |
2001年 | 620篇 |
2000年 | 658篇 |
1999年 | 570篇 |
1998年 | 439篇 |
1997年 | 406篇 |
1996年 | 404篇 |
1995年 | 377篇 |
1994年 | 379篇 |
1993年 | 367篇 |
1992年 | 427篇 |
1991年 | 372篇 |
1990年 | 334篇 |
1989年 | 344篇 |
1988年 | 346篇 |
1987年 | 297篇 |
1986年 | 286篇 |
1985年 | 324篇 |
1984年 | 328篇 |
1983年 | 293篇 |
1982年 | 269篇 |
1981年 | 226篇 |
1980年 | 210篇 |
1979年 | 235篇 |
1978年 | 203篇 |
1977年 | 186篇 |
1976年 | 176篇 |
1975年 | 181篇 |
1974年 | 150篇 |
1973年 | 136篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
12.
13.
Robert C. Cope Joshua V. Ross Talia A. Wittmann Michael J. Watts Phillip Cassey 《Risk analysis》2019,39(1):35-53
Understanding the risk of biological invasions associated with particular transport pathways and source regions is critical for implementing effective biosecurity management. This may require both a model for physical connectedness between regions, and a measure of environmental similarity, so as to quantify the potential for a species to be transported from a given region and to survive at a destination region. We present an analysis of integrated biosecurity risk into Australia, based on flights and shipping data from each global geopolitical region, and an adaptation of the “range bagging” method to determine environmental matching between regions. Here, we describe global patterns of environmental matching and highlight those regions with many physical connections. We classify patterns of global invasion risk (high to low) into Australian states and territories. We validate our analysis by comparison with global presence data for 844 phytophagous insect pest species, and produce a list of high‐risk species not previously known to be present in Australia. We determined that, of the insect pest species used for validation, the species most likely to be present in Australia were those also present in geopolitical regions with high transport connectivity to Australia, and those regions that were geographically close, and had similar environments. 相似文献
14.
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
15.
Aggressive behavior in pet dogs is a serious problem for dog owners across the globe, with bite injuries representing a serious risk to both people and other dogs. The effective management of aggressive behavior in dogs represents a challenging and controversial issue. Although positive reinforcement training methods are now considered to be the most effective and humane technique to manage the risk of aggression, punishment‐based methods continue to be used. Unfortunately, there has been little scientific study into the various factors influencing whether dog owners choose to use positive reinforcement techniques to manage aggression in their dogs. As such, current understanding of how best to encourage and support dog owners to use these methods remains extremely limited. This article uses a survey methodology based on protection motivation theory (PMT) to investigate the factors that influence owner use of positive reinforcement methods to manage aggressive behavior, in an attempt to understand potential barriers and drivers of use. In addition, the article provides an initial exploration of the potential role of wider psychological factors, including owner emotional state, social influence, and cognitive bias. Findings show that the perceived efficacy of positive reinforcement methods and the perceived ability of owners to effectively implement the technique are both key factors predicting future intentions and current reported use. Future interventions should focus on enhancing owner confidence in the effective use of positive reinforcement techniques across multiple scenarios, as well as helping owners manage their own emotional responses when they encounter challenging situations and setbacks. 相似文献
16.
Random effects regression mixture models are a way to classify longitudinal data (or trajectories) having possibly varying lengths. The mixture structure of the traditional random effects regression mixture model arises through the distribution of the random regression coefficients, which is assumed to be a mixture of multivariate normals. An extension of this standard model is presented that accounts for various levels of heterogeneity among the trajectories, depending on their assumed error structure. A standard likelihood ratio test is presented for testing this error structure assumption. Full details of an expectation-conditional maximization algorithm for maximum likelihood estimation are also presented. This model is used to analyze data from an infant habituation experiment, where it is desirable to assess whether infants comprise different populations in terms of their habituation time. 相似文献
17.
18.
19.
This paper considers whether gains made by shareholders from corporate takeovers are achieved at the expense of employees, as proposed by the ‘wealth transfer’ perspective. It analyses the contribution of employee lay‐offs, along with employment and wage changes, to the takeover premium and abnormal share price movements. The analysis draws on a unique dataset of British takeovers, combining documentary, share price and accounting data. The results show that lay‐offs planned at the takeover have either no effect or adverse effects on shareholder returns. Wages growth is positively, not inversely, related to shareholder returns from the second year after the takeover, whilst positive employment changes have a similar effect in the following year. Closer scrutiny indicates that labour and shareholders share gains when the firm does well, but share pain when it does not. There is evidence, therefore, that labour and shareholder interests can be complementary, rather than antagonistic, after takeovers. 相似文献
20.
David R. Bickel 《统计学通讯:理论与方法》2020,49(11):2703-2712
AbstractConfidence sets, p values, maximum likelihood estimates, and other results of non-Bayesian statistical methods may be adjusted to favor sampling distributions that are simple compared to others in the parametric family. The adjustments are derived from a prior likelihood function previously used to adjust posterior distributions. 相似文献