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   275篇
  免费   14篇
电工技术   3篇
化学工业   80篇
金属工艺   2篇
机械仪表   3篇
建筑科学   8篇
矿业工程   2篇
能源动力   11篇
轻工业   37篇
水利工程   3篇
无线电   20篇
一般工业技术   41篇
冶金工业   29篇
自动化技术   50篇
  2023年   8篇
  2022年   16篇
  2021年   23篇
  2020年   10篇
  2019年   13篇
  2018年   9篇
  2017年   8篇
  2016年   11篇
  2015年   11篇
  2014年   11篇
  2013年   14篇
  2012年   14篇
  2011年   18篇
  2010年   12篇
  2009年   16篇
  2008年   15篇
  2007年   8篇
  2006年   7篇
  2005年   9篇
  2004年   10篇
  2003年   7篇
  2002年   3篇
  2001年   1篇
  2000年   1篇
  1998年   1篇
  1997年   1篇
  1996年   1篇
  1995年   1篇
  1994年   4篇
  1993年   1篇
  1992年   2篇
  1991年   1篇
  1990年   1篇
  1988年   1篇
  1987年   1篇
  1986年   4篇
  1985年   2篇
  1983年   2篇
  1982年   2篇
  1980年   1篇
  1979年   1篇
  1978年   3篇
  1977年   1篇
  1976年   1篇
  1966年   1篇
  1961年   1篇
排序方式: 共有289条查询结果,搜索用时 15 毫秒
281.
A Dynamic Travel Time Model for Spillback   总被引:1,自引:1,他引:0  
In this paper we introduce travel time models that incorporate spillback and bottleneck phenomena. In particular, we study a model for determining the link travel times for drivers entering a link as well as drivers already in the link but whose travel times are affected by a significant change in traffic conditions (e.g. spillback or bottleneck phenomena). To achieve this goal, we extend the fluid dynamics travel time models proposed by Perakis (1997)and subsequently by Kachani (2002), and Kachani and Perakis (2001), to also incorporate such phenomena. These models utilize fluid dynamics laws for compressible flow to capture a variety of flow patterns such as the formation and dissipation of queues, drivers’ response to upstream congestion or decongestion and drivers’ reaction time. We propose variants of these models that explicitly account for spillback and bottleneck phenomena. Our investigation considers both separable and non-separable velocity functions.  相似文献   
282.
Formal mentoring: Lessons learned from past practice.   总被引:1,自引:0,他引:1  
Formal mentoring programs are often implemented to help early career professionals; however, research on these programs has found mixed support. The general literature on formal mentoring programs has shifted from early studies comparing informal and formal mentoring to studies of the program characteristics related to success. A pilot program for formal mentoring of early career psychologists is presented for case study. Although the program was small and matching mentors and mentees proved difficult, reactions from some participants indicated successful mentoring. Drawing on lessons learned from the program and the general literature on formal mentoring, the author focuses on the matching process, training and program resources, and program administration. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
283.
Context-aware service engineering: A survey   总被引:2,自引:0,他引:2  
Context constitutes an essential part of service behaviour, especially when interaction with end-users is involved. As observed from the literature, context handling in service engineering has been during recent years a field of intense research, which has produced several interesting approaches. In this paper, we present research efforts that attempt mainly to decouple context handling from the service logic. We enumerate all context management categories, but focus on the most appropriate for service engineering, namely source code level, model-driven and message interception, taking also into account the fact that these have not been dealt with in detail in other surveys. A representative example is used to illustrate more precisely how these approaches can be used. Finally, all three categories are compared based on a number of criteria.  相似文献   
284.
Panagiotis Isigonis  Antreas Afantitis  Dalila Antunes  Alena Bartonova  Ali Beitollahi  Nils Bohmer  Evert Bouman  Qasim Chaudhry  Mihaela Roxana Cimpan  Emil Cimpan  Shareen Doak  Damien Dupin  Doreen Fedrigo  Valrie Fessard  Maciej Gromelski  Arno C. Gutleb  Sabina Halappanavar  Peter Hoet  Nina Jeliazkova  Stphane Jomini  Sabine Lindner  Igor Linkov  Eleonora Marta Longhin  Iseult Lynch  Ineke Malsch  Antonio Marcomini  Espen Mariussen  Jesus M. de la Fuente  Georgia Melagraki  Finbarr Murphy  Michael Neaves  Rolf Packroff  Stefan Pfuhler  Tomasz Puzyn  Qamar Rahman  Elise Rundn Pran  Elena Semenzin  Tommaso Serchi  Christoph Steinbach  Benjamin Trump  Ivana Vinkovi&#x; Vr ek  David Warheit  Mark R. Wiesner  Egon Willighagen  Maria Dusinska 《Small (Weinheim an der Bergstrasse, Germany)》2020,16(36)
Nanotechnologies have reached maturity and market penetration that require nano‐specific changes in legislation and harmonization among legislation domains, such as the amendments to REACH for nanomaterials (NMs) which came into force in 2020. Thus, an assessment of the components and regulatory boundaries of NMs risk governance is timely, alongside related methods and tools, as part of the global efforts to optimise nanosafety and integrate it into product design processes, via Safe(r)‐by‐Design (SbD) concepts. This paper provides an overview of the state‐of‐the‐art regarding risk governance of NMs and lays out the theoretical basis for the development and implementation of an effective, trustworthy and transparent risk governance framework for NMs. The proposed framework enables continuous integration of the evolving state of the science, leverages best practice from contiguous disciplines and facilitates responsive re‐thinking of nanosafety governance to meet future needs. To achieve and operationalise such framework, a science‐based Risk Governance Council (RGC) for NMs is being developed. The framework will provide a toolkit for independent NMs' risk governance and integrates needs and views of stakeholders. An extension of this framework to relevant advanced materials and emerging technologies is also envisaged, in view of future foundations of risk research in Europe and globally.  相似文献   
285.
As-prepared, single-crystalline bismuth ferrite nanoparticles show strong size-dependent magnetic properties that correlate with: (a) increased suppression of the known spiral spin structure (period length of approximately 62 nm) with decreasing nanoparticle size and (b) uncompensated spins and strain anisotropies at the surface. Zero-field-cooled and field-cooled magnetization curves exhibit spin-glass freezing behavior due to a complex interplay between finite size effects, interparticle interactions, and a random distribution of anisotropy axes in our nanoparticle assemblies.  相似文献   
286.
An increasing number of studies have profiled gene expressions in tumor specimens using distinct microarray platforms and analysis techniques. One challenging task is to develop robust statistical models in order to integrate multi-platform findings. We compare some methodologies on the field with respect to estrogen receptor (ER) status, and focus on a unified-among-platforms scale implemented by Shen et al. in 2004, which is based on a Bayesian mixture model. Under this scale, we study the ER intensity similarities between four breast cancer datasets derived from various platforms. We evaluate our results with an independent dataset in terms of ER sample classification, given the derived gene ER signatures of the integrated data. We found that integrated multi-platform gene signatures and fold-change variability similarities between different platform measurements can assist the statistical analysis of independent microarray datasets in terms of ER classification.  相似文献   
287.
288.
289.
New product diffusion process studies focus mainly on estimating the adoption rate of the product, within the boundaries of the targeted market. However, and especially for high technology and telecommunications products, it is very likely the case that products or services are introduced simultaneously into a number of market segments, a fact that it is rarely taken into account. Thus, the effect of market and population interaction, and the consequent co-influence in the diffusion rates is not considered. This work focuses on developing and evaluating a pertinent methodology, so as to capture this cross-national interaction influence in the diffusion process.  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