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   608篇
  免费   11篇
  国内免费   18篇
管理学   89篇
民族学   3篇
人口学   3篇
丛书文集   18篇
理论方法论   7篇
综合类   441篇
社会学   29篇
统计学   47篇
  2024年   1篇
  2023年   12篇
  2022年   10篇
  2021年   11篇
  2020年   11篇
  2019年   14篇
  2018年   13篇
  2017年   15篇
  2016年   30篇
  2015年   28篇
  2014年   42篇
  2013年   49篇
  2012年   30篇
  2011年   39篇
  2010年   33篇
  2009年   32篇
  2008年   35篇
  2007年   33篇
  2006年   30篇
  2005年   39篇
  2004年   26篇
  2003年   16篇
  2002年   23篇
  2001年   10篇
  2000年   13篇
  1999年   7篇
  1998年   7篇
  1997年   2篇
  1996年   5篇
  1995年   4篇
  1994年   12篇
  1992年   1篇
  1991年   1篇
  1989年   1篇
  1988年   2篇
排序方式: 共有637条查询结果,搜索用时 31 毫秒
81.
介绍了印刷烫金机走纸控制器软硬件的设计方案,该控制器选用低栅压导通的功率场效应管作为步进电机驱动,控制CPU采用AVR单片机.控制器具有走纸长度设置、电机启停低速而运行高速、走纸完毕声光提示、设置参数掉电保护等功能.  相似文献   
82.
作为“纯艺术”的表现主义绘画,与作为实用艺术的现代包装设计,都基于共同的平面性质,二者在某种程度上有着密切的联系.尤其是表现主义诞生之日起,便以一个全新的理念与具有视觉冲击力的表现手法,打破了人们的视觉习惯,同时也给平面设计带来了巨大的影响,使包装设计多了一种样式.包装平面设计在借鉴表现主义版画的艺术观念时要注意利弊,过度地使用艺术语言会使设计作品削弱其实用价值,这就要求设计师具有较强的思考能力.  相似文献   
83.
Summary: The next German census will be an Administrative Record Census. Data from several administrative registers about persons will be merged. Object identification has to be applied, since no unique identification number exists in the registers. We present a two–step procedure. We briefly discuss questions like correctness and completeness of the Administrative Record Census. Then we focus on the object identification problem, that can be perceived as a special classification problem. Pairs of records are to be classified as matched or not matched. To achieve computational efficiency a preselection technique of pairs is applied. Our approach is illustrated with a database containing a large set of consumer addresses.*This work was partially supported by the Berlin–Brandenburg Graduate School in Distributed Information Systems (DFG grant no. GRK 316). The authors thank Michael Fürnrohr for previewing the paper. We would like to thank also for the helpful comments of an anonymous reviewer.  相似文献   
84.
针对肉食品专营店和餐饮店对冷冻肉的解冻需求,设计研制了一台新型高压静电解冻柜。该解冻柜采用了高压静电解冻技术。设计了基于可编程逻辑控制器( PLC)的控制系统,可自动调控解冻柜温湿度和电场强度。根据设计性能参数,计算了解冻过程所需加热、制冷负荷和加湿蒸汽量。经解冻实验表明,该解冻柜能缩短解冻时间,降低汁液流失率,抑制微生物的繁殖,且解冻后肉样外观新鲜,肉色泽鲜红,具有实际应用价值。  相似文献   
85.
阐述了在网络环境下网络本土化和机器翻译对翻译产业化的影响,分析了国内外翻译人才数量、行业需求变化,通过对传统翻译和网络翻译在运作模式上的比较,对翻译工作者如何应对互联网的挑战提出了要求.  相似文献   
86.
Abstract

Research involving administrative healthcare data to study patient outcomes requires the investigator to account for the patient’s disease burden in order to reduce the potential for biased results. Here we develop a comorbidity summary score based on variable importance measures derived from several statistical and machine learning methods and show it has superior predictive performance to the Elixhauser and Charlson indices when used to predict 1-year, 5-year, and 10-year mortality. We used two large Veterans Administration cohorts to develop and validate the summary score and compared predictive performance using the area under ROC curve (AUC) and the Brier score.  相似文献   
87.
ABSTRACT

The support vector machine (SVM), first developed by Vapnik and his group at AT&T Bell Laboratories, is being used as a new technique for regression and classification problems. In this paper we present an approach to estimating prediction intervals for SVM regression based on posterior predictive densities. Furthermore, the method is illustrated with a data example.  相似文献   
88.
This article focuses on conceptual and methodological developments allowing the integration of physical and social dynamics leading to model forecasts of circumstance‐specific human losses during a flash flood. To reach this objective, a random forest classifier is applied to assess the likelihood of fatality occurrence for a given circumstance as a function of representative indicators. Here, vehicle‐related circumstance is chosen as the literature indicates that most fatalities from flash flooding fall in this category. A database of flash flood events, with and without human losses from 2001 to 2011 in the United States, is supplemented with other variables describing the storm event, the spatial distribution of the sensitive characteristics of the exposed population, and built environment at the county level. The catastrophic flash floods of May 2015 in the states of Texas and Oklahoma are used as a case study to map the dynamics of the estimated probabilistic human risk on a daily scale. The results indicate the importance of time‐ and space‐dependent human vulnerability and risk assessment for short‐fuse flood events. The need for more systematic human impact data collection is also highlighted to advance impact‐based predictive models for flash flood casualties using machine‐learning approaches in the future.  相似文献   
89.
In a clinical trial, sometimes it is desirable to allocate as many patients as possible to the best treatment, in particular, when a trial for a rare disease may contain a considerable portion of the whole target population. The Gittins index rule is a powerful tool for sequentially allocating patients to the best treatment based on the responses of patients already treated. However, its application in clinical trials is limited due to technical complexity and lack of randomness. Thompson sampling is an appealing approach, since it makes a compromise between optimal treatment allocation and randomness with some desirable optimal properties in the machine learning context. However, in clinical trial settings, multiple simulation studies have shown disappointing results with Thompson samplers. We consider how to improve short-run performance of Thompson sampling and propose a novel acceleration approach. This approach can also be applied to situations when patients can only be allocated by batch and is very easy to implement without using complex algorithms. A simulation study showed that this approach could improve the performance of Thompson sampling in terms of average total response rate. An application to a redesign of a preference trial to maximize patient's satisfaction is also presented.  相似文献   
90.
针对现有桶装水灌装生产线中灌装机产能较低、产品适应能力差的缺点,提出了能够适用于19升、17升、11升等多种桶型的高速柔性化灌装机的设计方案。灌装机的灌装头采用气动比例调节阀搭配传感器进行闭环控制,使得灌装液位精确,减少液体飞溅;进瓶装置采用星轮拨爪和由伺服电机驱动的链条传动装置联动的方式,实现水桶的精准拉距,实现多种瓶型快速切换的功能;瓶盖输送机构,结合盖子杀菌柜,实现在线杀菌功能,安全可靠。应用结果表明文章的设计能改善原有桶装水灌装机柔性差、速度慢、可靠性低的现状。优化设计的桶装水灌装机提高了生产效率,降低成本。  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