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   12671篇
  免费   298篇
管理学   1649篇
民族学   52篇
人才学   1篇
人口学   1097篇
丛书文集   78篇
教育普及   2篇
理论方法论   1172篇
综合类   337篇
社会学   6365篇
统计学   2216篇
  2021年   67篇
  2020年   189篇
  2019年   220篇
  2018年   245篇
  2017年   368篇
  2016年   284篇
  2015年   230篇
  2014年   255篇
  2013年   2054篇
  2012年   394篇
  2011年   318篇
  2010年   211篇
  2009年   236篇
  2008年   262篇
  2007年   278篇
  2006年   217篇
  2005年   351篇
  2004年   296篇
  2003年   258篇
  2002年   268篇
  2001年   314篇
  2000年   297篇
  1999年   309篇
  1998年   209篇
  1997年   205篇
  1996年   214篇
  1995年   188篇
  1994年   205篇
  1993年   178篇
  1992年   237篇
  1991年   232篇
  1990年   214篇
  1989年   220篇
  1988年   195篇
  1987年   186篇
  1986年   189篇
  1985年   174篇
  1984年   207篇
  1983年   200篇
  1982年   165篇
  1981年   137篇
  1980年   139篇
  1979年   166篇
  1978年   136篇
  1977年   119篇
  1976年   102篇
  1975年   102篇
  1974年   96篇
  1973年   93篇
  1971年   64篇
排序方式: 共有10000条查询结果,搜索用时 578 毫秒
331.
The aim of this study was to develop a modified quantitative microbial risk assessment (QMRA) framework that could be applied as a decision support tool to choose between alternative drinking water interventions in the developing context. The impact of different household water treatment (HWT) interventions on the overall incidence of diarrheal disease and disability adjusted life years (DALYs) was estimated, without relying on source water pathogen concentration as the starting point for the analysis. A framework was developed and a software tool constructed and then implemented for an illustrative case study for Nepal based on published scientific data. Coagulation combined with free chlorine disinfection provided the greatest estimated health gains in the short term; however, when long‐term compliance was incorporated into the calculations, the preferred intervention was porous ceramic filtration. The model demonstrates how the QMRA framework can be used to integrate evidence from different studies to inform management decisions, and in particular to prioritize the next best intervention with respect to estimated reduction in diarrheal incidence. This study only considered HWT interventions; it is recognized that a systematic consideration of sanitation, recreation, and drinking water pathways is important for effective management of waterborne transmission of pathogens, and the approach could be expanded to consider the broader water‐related context.  相似文献   
332.
Urban-associated changes can have immediate or long-term consequences on animal populations. Such changes may be assessed through parasite prevalence and abundance in wildlife hosts, as urbanization can influence parasitism and disease transmission in wildlife. Snakes are widespread and diverse vertebrates that often persist in urban environments; however, parasitism of snakes in urban environments has yet to be studied, leaving the roles of snakes in parasite transmission uncharacterized. Field ecology, microscopy, molecular techniques, and geographic information science (GIS) were integrated to characterize parasitism of snakes in an urban old-growth forest park. The species, sex, mass, length, location, and prevalence of ecto-, hemo-, and fecal parasites were determined for 34 snakes of 6 species. Ectoparasites (mite), hemoparasites (Hepatozoon spp.), and fecal parasites (Entamoeba spp., Trichomonas spp., Strongloides spp., and an unidentified helminth) were detected in snakes and 64.7?% of snakes were infected by at least one of these parasites. Parasite infections were generally not related to the sex, age, or body condition of snakes. The locations of infected snakes were used to produce risk maps indicating where parasite prevalence is predicted to be greatest. The analysis of these maps indicated that snakes with fecal parasites were closer than non-infected snakes to the edge of the forest. This study confirms that snakes may be important parasite hosts or reservoirs in parasite transmission pathways in urban environments and it provides an integrative multidisciplinary approach that may be used to monitor parasitism dynamics in other urban wildlife areas.  相似文献   
333.
334.
Welfare state studies are usually motivated by one or both of two concerns: programme effects on the incidence of poverty, and the possibility of perverse incentive effects. Most research has been comparative, using cross‐national indicators from the Organisation for Economic Co‐operation and Development and other international organizations. That research often contrasts the generosity of programmes in a number of European countries and the lack of it in the USA. Focusing on income transfers after job‐loss, in this article we critically examine the comparative evidence on US welfare state generosity and then use the Panel Study of Income Dynamics (PSID) to estimate what happens to job‐losers' incomes. The comparative analysis suggests conclusions more nuanced than found in much of the literature. The PSID analysis shows how the income effects of job‐loss vary across job‐losers and suggests that the role of unemployment compensation programmes in supporting incomes may be overstated.  相似文献   
335.
The cost of an uncontrolled incursion of invasive alien species (IAS) arising from undetected entry through ports can be substantial, and knowledge of port‐specific risks is needed to help allocate limited surveillance resources. Quantifying the establishment likelihood of such an incursion requires quantifying the ability of a species to enter, establish, and spread. Estimation of the approach rate of IAS into ports provides a measure of likelihood of entry. Data on the approach rate of IAS are typically sparse, and the combinations of risk factors relating to country of origin and port of arrival diverse. This presents challenges to making formal statistical inference on establishment likelihood. Here we demonstrate how these challenges can be overcome with judicious use of mixed‐effects models when estimating the incursion likelihood into Australia of the European (Apis mellifera) and Asian (A. cerana) honeybees, along with the invasive parasites of biosecurity concern they host (e.g., Varroa destructor). Our results demonstrate how skewed the establishment likelihood is, with one‐tenth of the ports accounting for 80% or more of the likelihood for both species. These results have been utilized by biosecurity agencies in the allocation of resources to the surveillance of maritime ports.  相似文献   
336.
Self-report purchase tasks are a novel approach examining the reinforcing value of addictive behaviour relative to increasing monetary costs required to access the addictive behaviour (i.e. demand). These measures reveal a positive relationship between the indices of demand and addiction problem severity and can elucidate factors associated with motivation for substance use. Gambling is an addictive behaviour that has not been examined using this paradigm. This study seeks to adapt and examine the purchase task for gambling behaviour. A gambling purchase task was devised that asked individuals how often per month they would gamble at various cover charges. Participants were 73 adults from the community with either gambling disorder (n = 28) or alcohol use disorder (n = 24) or were a healthy control (n = 21). Both the alcohol and gambling purchase tasks were administered. Results demonstrate discriminant validity of the gambling purchase task, as individuals with gambling disorder have significantly greater demand for accessing gambling than other groups. The alcohol purchase task also evidenced discriminant validity in that individuals with alcohol use disorder have significantly greater demand for alcohol than other groups. These findings support the use of the gambling purchase task to assess the demand for gambling.  相似文献   
337.
338.
The objective of this article is to discuss a needed paradigm shift in disaster risk analysis to emphasize the role of the workforce in managing the recovery of interdependent infrastructure and economic systems. Much of the work that has been done on disaster risk analysis has focused primarily on preparedness and recovery strategies for disrupted infrastructure systems. The reliability of systems such as transportation, electric power, and telecommunications is crucial in sustaining business processes, supply chains, and regional livelihoods, as well as ensuring the availability of vital services in the aftermath of disasters. There has been a growing momentum in recognizing workforce criticality in the aftermath of disasters; nevertheless, significant gaps still remain in modeling, assessing, and managing workforce disruptions and their associated ripple effects to other interdependent systems. The workforce plays a pivotal role in ensuring that a disrupted region continues to function and subsequently recover from the adverse effects of disasters. With this in mind, this article presents a review of recent studies that have underscored the criticality of workforce sectors in formulating synergistic preparedness and recovery policies for interdependent infrastructure and regional economic systems.  相似文献   
339.
340.
Joost R. Santos 《Risk analysis》2012,32(10):1673-1692
Disruptions in the production of commodities and services resulting from disasters influence the vital functions of infrastructure and economic sectors within a region. The interdependencies inherent among these sectors trigger the faster propagation of disaster consequences that are often associated with a wider range of inoperability and amplified losses. This article evaluates the impact of inventory‐enhanced policies for disrupted interdependent sectors to improve the disaster preparedness capability of dynamic inoperability input‐output models (DIIM). In this article, we develop the dynamic cross‐prioritization plot (DCPP)—a prioritization methodology capable of identifying and dynamically updating the critical sectors based on preference assignments to different objectives. The DCPP integrates the risk assessment metrics (e.g., economic loss and inoperability), which are independently analyzed in the DIIM. We develop a computer‐based DCPP tool to determine the priority for inventory enhancement with user preference and resource availability as new dimensions. A baseline inventory case for the state of Virginia revealed a high concentration of (i) manufacturing sectors under the inoperability objective and (ii) service sectors under the economic loss objective. Simulation of enhanced inventory policies for selected critical manufacturing sectors has reduced the recovery period by approximately four days and the expected total economic loss by $33 million. Although the article focuses on enhancing inventory levels in manufacturing sectors, complementary analysis is recommended to manage the resilience of the service sectors. The flexibility of the proposed DCPP as a decision support tool can also be extended to accommodate analysis in other regions and disaster scenarios.  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