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   17157篇
  免费   1684篇
  国内免费   1550篇
电工技术   1384篇
技术理论   3篇
综合类   2235篇
化学工业   357篇
金属工艺   383篇
机械仪表   848篇
建筑科学   1334篇
矿业工程   311篇
能源动力   162篇
轻工业   204篇
水利工程   337篇
石油天然气   282篇
武器工业   85篇
无线电   3542篇
一般工业技术   1165篇
冶金工业   579篇
原子能技术   16篇
自动化技术   7164篇
  2024年   63篇
  2023年   191篇
  2022年   369篇
  2021年   409篇
  2020年   574篇
  2019年   373篇
  2018年   444篇
  2017年   434篇
  2016年   483篇
  2015年   636篇
  2014年   1136篇
  2013年   1145篇
  2012年   1373篇
  2011年   1413篇
  2010年   1123篇
  2009年   1214篇
  2008年   1317篇
  2007年   1428篇
  2006年   1225篇
  2005年   1155篇
  2004年   942篇
  2003年   746篇
  2002年   563篇
  2001年   421篇
  2000年   358篇
  1999年   215篇
  1998年   147篇
  1997年   114篇
  1996年   92篇
  1995年   68篇
  1994年   67篇
  1993年   33篇
  1992年   17篇
  1991年   13篇
  1990年   13篇
  1989年   12篇
  1988年   8篇
  1987年   5篇
  1986年   7篇
  1985年   4篇
  1984年   4篇
  1982年   4篇
  1981年   6篇
  1980年   5篇
  1979年   2篇
  1973年   3篇
  1958年   2篇
  1957年   2篇
  1956年   2篇
  1955年   2篇
排序方式: 共有10000条查询结果,搜索用时 390 毫秒
961.
《Information & Management》2016,53(5):668-681
Prior research has shown how consumer perception, when risk is an important factor, may affect the adoption and the usage of E-payment service. Given this general knowledge, this study investigates the more specific issues of the mix of design attributes to drive consumer choice in using E-payment services. Using six design attributes defined by a group of practitioners and E-payment service users using the Delphi method, an online conjoint experiment is conducted. We find out how these design attributes may affect consumer choice under risk and the rank order of the magnitudes of their effects.  相似文献   
962.
运用微信公众号,结合水利汛情综合数据,发布汛情信息和水利应对气候变化信息,组建水利信息服务平台。通过服务器向授权注册用户群发布文本、声音、图像、视频、图文等汛情信息和水利应对气候变化信息,实现图文并茂信息推送、汛情查询、气象动态、互动服务等功能。系统采用多进程并发命令,快速发布汛情信息;用户可以随时随地进行汛情险情上报。系统信息发布迅速,内容丰富,有效提高防汛应急响应及防灾减灾能力。  相似文献   
963.
随着国内家政行业进阶为万亿级市场,家政业务交易额每年增幅都超过20%.家政O2O作为大众期望的一种运营模式,刚好能迎合这样快速发展的家政市场.首先介绍了国内家政服务市场的现状,然后分析了家政O2O的发展基础,最后以95081的家政O2O模式为例,分析了国内家政O2O的出路.  相似文献   
964.
We present a method through which domestic service robots can comprehend natural language instructions. For each action type, a variety of natural language expressions can be used, for example, the instruction, ‘Go to the kitchen’ can also be expressed as ‘Move to the kitchen.’ We are of the view that natural language instructions are intuitive and, therefore, constitute one of the most user-friendly robot instruction methods. In this paper, we propose a method that enables robots to comprehend instructions spoken by a human user in his/her natural language. The proposed method combines action-type classification, which is based on a support vector machine, and slot extraction, which is based on conditional random fields, both of which are required in order for a robot to execute an action. Further, by considering the co-occurrence relationship between the action type and the slots along with the speech recognition score, the proposed method can avoid degradation of the robot’s comprehension accuracy in noisy environments, where inaccurate speech recognition can be problematic. We conducted experiments using a Japanese instruction data-set collected using a questionnaire-based survey. Experimental results show that the robot’s comprehension accuracy is higher in a noisy environment using our method than when using a baseline method with only a 1-best speech recognition result.  相似文献   
965.
We present two integrated network design and inventory control problems in service-parts logistics systems. Such models are complicated due to demand uncertainty and highly nonlinear time-based service level constraints. Exploiting unique properties of the nonlinear constraints, we provide an equivalent linear formulation under part-warehouse service requirements, and an approximate linear formulation under part service requirements. Computational results indicate the superiority of our approach over existing approaches in the literature.  相似文献   
966.
Emergency medical service (EMS) systems provide medical care and transportation. While many real‐world systems use multiple vehicle types to attend different call priorities, few guidelines exist about which vehicles to allocate in multitiered responses where more than one vehicle is sent per call. This paper makes recommendations for multiple‐unit dispatch to multiple call priorities based on simulation optimization and heuristics. The objective is to maximize the overall expected survival probability of patients classified as “life‐threatening”. We assume two types of medical units and three call priorities; and that information may be updated when the medical unit arrives on‐scene. First, we study the optimal dispatching policies through several examples. Numerical results show that dispatching while considering call priorities, rather than dispatching the closest units, improves EMS system effectiveness. A heuristic algorithm is developed for large‐scale problems. A comparison between the heuristic and closest policy is demonstrated using real‐world data.  相似文献   
967.
《国际生产研究杂志》2012,50(5):1438-1456
This paper proposes a mixed-integer programming (MIP) model for the strategic production and distribution planning of a supply chain (SC) integrating reverse logistics system. Such reverse logistics planning addresses the collection, recovery and marketing of recovered products, in addition to returned components and packing/wrapping materials. The model includes an approach that uses retail outlets as a two-way channel for marketing new products, collecting used/returned products and remarketing recovered products as a way of promoting an effective product recovery system in SC operation and optimising costs. The recovery of products/components is planned through a pool of recovery service providers (RSPs), so that maximum recovery can be ensured through combining the expertise of RSPs within optimum costs. The model follows a two-step process that addresses strategic decisions about product recovery in the first step, and the integration of the recovery process into overall SC decisions in the final step. A numerical example illustrates the applicability of the model. A sensitivity analysis has been conducted to show the effects that changes in the recovered product quantity have on the overall SC performance.  相似文献   
968.
There has been an increasing awareness that large-scale datasets of earth-system model results would be produced and accumulated rapidly within the next few decades with extensive usage of numerical models. The successful exploration of these data for scientific research and engineering applications requires the capability of efficient storage, retrieval, integration and visualization of these large datasets. Robust publication methods are also needed to enable data exchange through the web to increase global research collaborations. In this study, a comprehensive GIS-based data management and publication framework (GMPF) was developed and applied to the use, representation, and analysis of hydrodynamic modeling results of Hamburg Port, Germany. Linking with GIS, a desktop- and a web-based model-results data atlas were developed to provide an interactive environment for various cartography and time series plots. The implementation of the framework was based on modular software design, open specifications and reuse of open source projects. The study results showed that the project life-cycle was shortened and development efforts were reduced through applying GMPF. The developed system could be integrated into commercial hydrodynamics software platforms to enhance the capability of model-results management and publication.  相似文献   
969.
The process of loading a stretcher into an ambulance is known to cause a high incidence of back injuries among paramedics. This study aimed to assess the forces at L5/S1 during real-life stretcher loading activities and to determine the variables that contribute significantly to these forces. Analyses involved 58 paramedics (111 shifts) and 175 stretcher loading activities. Estimates of compression and shear forces at L5/S1 were calculated using the 3DSSPP program. Seventy-one percent of loading activities exceeded the safe loading level of 3.4 kN compression force at L5/S1 (mean: 3.9 kN, min–max: 2.1–7.0 kN). About 92% of the variance can be predicted from a combination of several variables, notably hand load (mean: 0.72 kN/number of paramedics) and back sagittal flexion (mean: 32°). Recommendations to reduce the risk of back injuries are proposed with regard to stretcher and ambulance loading design as well as training in stretcher lifting for paramedics.Relevance to the industryThe results of this study suggest that ambulance stretcher manufacturers should make ergonomic design changes to reduce the physical strain on paramedics’ backs during the process of loading a stretcher into an ambulance. Other preventive measures (e.g., training) must be formulated and applied to reduce the risk of back musculoskeletal disorders during the loading of stretcher patients. For instance, training should focus on back posture, teamwork and equipment/patient positioning on stretchers.  相似文献   
970.
This article analyses public service broadcasting in Europe, looking at public broadcasters' role as promoters of participative processes. Computer‐mediated communication and studies rooted in mediated human interactivity are used to explore participative elements provided by digital technology, and how these can be incorporated into the news websites, through an empirical study of 5 case studies in the European market. The analysis is based on the methodology of content analysis with the goal of outlining the particularities of the participative elements implemented by each broadcaster and revealing the most common participative strategies. The findings suggest that although public service broadcasters offer a wide variety of possibilities, encouraging audiences to take on more active roles, their role is still peripheral and complementary.  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