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:      
  示例: 沙坡头地区,人工植被区,变化  检索词用空格隔开表示必须包含全部检索词,用“,”隔开表示只需满足任一检索词即可!
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   2850篇
  免费   7篇
管理学   583篇
民族学   22篇
人口学   298篇
丛书文集   10篇
理论方法论   222篇
综合类   25篇
社会学   1297篇
统计学   400篇
  2024年   19篇
  2023年   37篇
  2022年   17篇
  2021年   27篇
  2020年   53篇
  2019年   81篇
  2018年   133篇
  2017年   149篇
  2016年   139篇
  2015年   96篇
  2014年   119篇
  2013年   436篇
  2012年   120篇
  2011年   93篇
  2010年   102篇
  2009年   103篇
  2008年   85篇
  2007年   97篇
  2006年   109篇
  2005年   75篇
  2004年   67篇
  2003年   56篇
  2002年   75篇
  2001年   72篇
  2000年   60篇
  1999年   39篇
  1998年   29篇
  1997年   18篇
  1996年   20篇
  1995年   20篇
  1994年   19篇
  1993年   12篇
  1992年   21篇
  1991年   27篇
  1990年   18篇
  1989年   13篇
  1988年   18篇
  1987年   9篇
  1986年   9篇
  1985年   12篇
  1984年   10篇
  1983年   19篇
  1982年   14篇
  1981年   11篇
  1980年   22篇
  1979年   9篇
  1978年   8篇
  1977年   8篇
  1975年   9篇
  1974年   9篇
排序方式: 共有2857条查询结果,搜索用时 0 毫秒
41.
    
Abstract

The aim of the present study was to investigate the relationship between personality factors (hardiness, morningness, flexibility, and languidity) and longitudinal changes on different measures of shift work tolerance (fatigue, sleepiness, anxiety and depression) over one year among nurses working rotating shifts. A total of 642 female Norwegian nurses working in a rotating three-shift schedule participated in the study. The cohort was established by age-stratified selection among members of the Norwegian Nurses Association in 2008. Questionnaires were administered in 2008/2009 (T1) and in 2009/2010 (T2). The results showed that hardiness was negatively related to fatigue, anxiety and depression at T2 when controlling for the scores on these constructs at T1. Morningness was not related to any indicators of shift work tolerance at T2 when controlling for shift work tolerance at T1. Flexibility was negatively related to anxiety at T2 when controlling for anxiety at T1. Languidity was positively related to sleepiness and fatigue at T2 when controlling for sleepiness and fatigue at T1. The findings indicate that personality factors, especially hardiness, can predict changes related to shift work tolerance over a period of one year.  相似文献   
42.
    
  相似文献   
43.
    

DEWIP is a manufacturing control system for job shop environments aiming at achieving short and reliable lead times by establishing WIP control loops between the manufacturing work centres. The paper describes the mode of function, the setting of parameters and simulation results of the new manufacturing control system. The setting of parameters is done with the aid of the funnel model and the theory of logistic operating curves, both developed at the Institute of Production Systems at the University of Hanover. The simulation is conducted using industrial data and makes it possible to assess DEWIP with regard to lead times, WIP level, performance and schedule reliability. DEWIP is compared both with an uncontrolled process and with the manufacturing control systems Load oriented order release (LOOR), Conwip and Polca. The results suggest that DEWIP and the models employed for the setting of parameters are suitable for job shop production and therefore offer a valuable alternative to prevailing centralized manufacturing control systems.  相似文献   
44.
    
Environmentally responsible manufacturing, green supply chain management (GSCM), and related principles have become important strategies for companies to achieve profit and gain market share by lowering their environmental impacts and increasing their efficiency. As environment has become a key strategic consideration in supply chains, this study examines the components and elements of GSCM and suggests a novel GSCM evaluation framework. It also provides a real-case study of Ford Otosan, one of the pioneering companies about environmental subjects in Turkey, to illustrate the industrial application of our theoretical assessment model. The identified components are integrated into a strategic assessment and evaluation tool using analytical network process (ANP). The dynamic characteristics and complexity of the GSCM analysis environment make the ANP technique a suitable tool for this study. Moreover, to cope with ambiguity and vagueness of the decision maker's evaluations, the fuzzy extension of the ANP method is preferred.  相似文献   
45.
    
W. G. Cochran's Q statistic was introduced in 1937 to test for equality of means under heteroscedasticity. Today, the use of Q is widespread in tests for homogeneity of effects in meta‐analysis, but often these effects (such as risk differences and odds ratios) are not normally distributed. It is common to assume that Q follows a chi‐square distribution, but it has long been known that this asymptotic distribution for Q is not accurate for moderate sample sizes. In this paper, the effect and weight for an individual study may depend on two parameters: the effect and a nuisance parameter. We present expansions for the first two moments of Q without any normality assumptions. Our expansions will have wide applicability in testing for homogeneity in meta‐analysis. As an important example, we present a homogeneity test when the effects are the differences of risks between treatment and control arms of the several studies—a test which is substantially more accurate than that currently used. In this situation, we approximate the distribution of Q with a gamma distribution. We provide the results of simulations to verify the accuracy of our proposal and an example of a meta‐analysis of medical data. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   
46.
    
International regulatory authorities view risk management as an essential production need for the development of innovative, somatic cell‐based therapies in regenerative medicine. The available risk management guidelines, however, provide little guidance on specific risk analysis approaches and procedures applicable in clinical cell therapy manufacturing. This raises a number of problems. Cell manufacturing is a poorly automated process, prone to operator‐introduced variations, and affected by heterogeneity of the processed organs/tissues and lot‐dependent variability of reagent (e.g., collagenase) efficiency. In this study, the principal challenges faced in a cell‐based product manufacturing context (i.e., high dependence on human intervention and absence of reference standards for acceptable risk levels) are identified and addressed, and a risk management model approach applicable to manufacturing of cells for clinical use is described for the first time. The use of the heuristic and pseudo‐quantitative failure mode and effect analysis/failure mode and critical effect analysis risk analysis technique associated with direct estimation of severity, occurrence, and detection is, in this specific context, as effective as, but more efficient than, the analytic hierarchy process. Moreover, a severity/occurrence matrix and Pareto analysis can be successfully adopted to identify priority failure modes on which to act to mitigate risks. The application of this approach to clinical cell therapy manufacturing in regenerative medicine is also discussed.  相似文献   
47.
    
Although the concept of safety culture was coined in relation to major accidents like Chernobyl and Piper Alpha, it has been embraced by the safety community at large as a cause for unsafe practice. In this article, three approaches to safety culture are discussed in terms of their underlying concepts of culture and organizational culture. Culture is an intangible, fuzzy concept encompassing acquired assumptions that is shared among the members of a group and that provides meaning to their perceptions and actions and those of others. The basic assumptions that form the essence of a culture are shared, yet tacit, convictions, which manifest themselves subtly in the visible world. As applied by safety researchers, the culture concept is deprived of much of its depth and subtlety, and is morphed into a grab bag of behavioral and other visible characteristics, without reference to the meaning these characteristics might actually have, and often infused with normative overtones. By combining the three approaches, we can resurrect the notion of safety culture and strengthen its analytical potential in understanding the development and implementation of safety management systems.  相似文献   
48.
    
Nanotechnologies operate at atomic, molecular, and macromolecular scales, at scales where matter behaves differently than at larger scales and quantum effects can dominate. Nanotechnologies have captured the imagination of science fiction writers as science, engineering, and industry have leapt to the challenge of harnessing them. Applications are proliferating. In contrast, despite recent progress the regulatory landscape is not yet coherent, and public awareness of nanotechnology remains low. This has led risk researchers and critics of current nanotechnology risk communication efforts to call for proactive strategies that do more than address facts, that include and go beyond the public participation stipulated by some government acts. A redoubling of nanotechnology risk communication efforts could enable consumer choice and informed public discourse about regulation and public investments in science and safety.  相似文献   
49.
    
In pest risk assessment it is frequently necessary to make management decisions regarding emerging threats under severe uncertainty. Although risk maps provide useful decision support for invasive alien species, they rarely address knowledge gaps associated with the underlying risk model or how they may change the risk estimates. Failure to recognize uncertainty leads to risk‐ignorant decisions and miscalculation of expected impacts as well as the costs required to minimize these impacts. Here we use the information gap concept to evaluate the robustness of risk maps to uncertainties in key assumptions about an invading organism. We generate risk maps with a spatial model of invasion that simulates potential entries of an invasive pest via international marine shipments, their spread through a landscape, and establishment on a susceptible host. In particular, we focus on the question of how much uncertainty in risk model assumptions can be tolerated before the risk map loses its value. We outline this approach with an example of a forest pest recently detected in North America, Sirex noctilio Fabricius. The results provide a spatial representation of the robustness of predictions of S. noctilio invasion risk to uncertainty and show major geographic hotspots where the consideration of uncertainty in model parameters may change management decisions about a new invasive pest. We then illustrate how the dependency between the extent of uncertainties and the degree of robustness of a risk map can be used to select a surveillance network design that is most robust to knowledge gaps about the pest.  相似文献   
50.
Coopetition has become a heated issue in the last decade. In this study, a scrutinized review of previous research on coopetition is presented to clarify the research stream on coopetition, from which the implications are derived and a framework to analyse the phenomenon is proposed. Given the complex nature of coopetition, an in‐depth case study was undertaken to investigate the competition–cooperation relationship and coopetition performance over a 15‐year period in a Taiwanese supermarket network, which was formed by a focal company and its competitors. Performance was analysed before and after launching the coopetition strategy, in which 31 indicators were examined. The findings imply that competition (Yang) and cooperation (Yin) are reciprocally rooted in and mutually promoted by each other. The findings also confirmed that cooperation with competitors did lead to better performance, at least over a period, in two ways. The first was that the adoption of coopetition permitted the attainment of performance levels beyond what would otherwise have been possible; the second was that the adoption of coopetition changed the timeframe, permitting earlier achievement of higher performance levels. This study contributes to and extends knowledge of the dynamics and consequences of cooperation with competitors and demonstrates that coopetition has a significant temporary advantage.  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