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   4805篇
  免费   194篇
  国内免费   61篇
电工技术   111篇
技术理论   2篇
综合类   342篇
化学工业   335篇
金属工艺   147篇
机械仪表   198篇
建筑科学   1610篇
矿业工程   250篇
能源动力   219篇
轻工业   253篇
水利工程   118篇
石油天然气   115篇
武器工业   13篇
无线电   226篇
一般工业技术   263篇
冶金工业   295篇
原子能技术   48篇
自动化技术   515篇
  2024年   14篇
  2023年   44篇
  2022年   66篇
  2021年   114篇
  2020年   124篇
  2019年   83篇
  2018年   64篇
  2017年   79篇
  2016年   158篇
  2015年   144篇
  2014年   283篇
  2013年   316篇
  2012年   294篇
  2011年   332篇
  2010年   259篇
  2009年   303篇
  2008年   239篇
  2007年   312篇
  2006年   267篇
  2005年   203篇
  2004年   188篇
  2003年   188篇
  2002年   162篇
  2001年   146篇
  2000年   126篇
  1999年   106篇
  1998年   92篇
  1997年   56篇
  1996年   54篇
  1995年   48篇
  1994年   42篇
  1993年   19篇
  1992年   18篇
  1991年   12篇
  1990年   8篇
  1989年   8篇
  1988年   7篇
  1987年   11篇
  1986年   5篇
  1985年   6篇
  1984年   7篇
  1983年   6篇
  1981年   13篇
  1980年   4篇
  1979年   5篇
  1975年   4篇
  1974年   2篇
  1958年   2篇
  1955年   2篇
  1954年   2篇
排序方式: 共有5060条查询结果,搜索用时 24 毫秒
41.
文章论述了萨沃伊别墅的机器美学思想,主要结合了勒·柯布西耶在1926年提出的"建筑新五点"来探讨他所主张的机器美学在萨沃伊别墅上是如何得以实现。  相似文献   
42.
43.
采用Flash Builder4.0、MyEclipse8.5为开发工具,Oracle 10g为数据库,开发了新病案首页系统,详细阐述了系统的设计流程、功能分析和数据库设计与实现。  相似文献   
44.
A number of reasons have been suggested for the rapid decline in influence and credibility experienced by William McDougall after his arrival in America. To obtain some evidence on this issue, all articles appearing in The New York Times between 1906 and 1940 in which McDougall was mentioned were coded for the nature of the image conveyed. Articles mentioning the two authors most similar to McDougall in terms of number of citations, Joseph Jastrow and Edward L. Thorndike, were also coded for the nature of the image conveyed. In contrast to the images of Jastrow and Thorndike, the image McDougall conveyed was significantly more negative. McDougall was more often satirized, and references to McDougall were significantly less likely to be simple reporting of something he had said or done. Results are discussed in terms of the role of the press in "deciding" controversies in which the scientific community has lost interest. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
45.
党的十八大以来,以习近平同志为核心的党中央高度重视家风建设在治国理政中的独特作用,深刻体现了家与国辩证统一的战略思维。优秀传统家训文化、马克思、恩格斯家庭观以及红色家风文化是新时代家风建设的思想基础。创造性转化和创新性发展优秀传统家训文化,继承和弘扬红色家风文化,运用好道德和制度两个杠杆,发挥好女性在家风建设中的重要作用是新时代家风建设的重要实践路径。  相似文献   
46.
This study addresses the question of how the electricity grid can best be priced, in the context of disruptive technologies, increasing decentralisation of the power sector and new business models. The emergence of business models can affect the design of tariffs, but at the same time, tariff design can trigger new business models as they can nudge adoption towards certain technologies. Network tariffs have traditionally been established using a cost accounting method. Due to its cost structure, network tariffs are second best constructs, as marginal cost pricing does not lead to cost recovery. Second best solutions, in all probability, will overcompensate some inputs which in turn will be overused (the Averch-Johnson effect). New distributed energy technologies that perform better in these overcompensated inputs will therefore see a higher penetration in the market. Penetration of some technologies over others in a previously monolithic vertically integrated power sector will open up new customer needs and therefore business opportunities. Each resulting business opportunity would make use of the grid differently from which it was originally conceived, and at one extreme, they can bypass it altogether. We provide a framework of analysis that leads to the pricing of the services provided by the electricity grid for each new business opportunity.  相似文献   
47.
新型滑靴式径向柱塞泵的降噪防漏措施   总被引:2,自引:0,他引:2  
严桃平  常绿 《机床与液压》2002,(5):193-193,192
本文介绍一种新型滑靴式径向柱塞泵的结构,分析其降噪防漏的措施。  相似文献   
48.
抄数系统在产品设计和模具制造中的应用   总被引:1,自引:0,他引:1  
介绍高速抄数机的基本结构、功能、工作流程以及在新产品开发,模具型腔、型芯设计和制造中的具体应用.  相似文献   
49.
介绍了中国石油吉林石化公司化肥厂合成氨装置的生产工艺和锅炉给水系统流程,分析了锅炉给水系统存在的问题,提出了改造方案和技术要求;阐述了新型除氧器的用途、原理及结构特点;介绍了除氧器改造后的运行效果及新型除氧器的优点。  相似文献   
50.
Future climate change is expected to have wide ranging impacts on the hydrology of mountain rivers because of changes in the magnitudes and timing of rain and snow, as well as the significant spatial variability of topography and other catchment characteristics. In New Zealand, hydropower generation in mountain basins is the primary source of electricity and renewable energy resource in the country. The goal of this study was to simulate and evaluate the potential effects of climate change on hydropower operations in three mountain headwater lakes (lakes Pukaki, Tekapo, and Ohau) in the Upper Waitaki Basin of the central South Island. The TopNet hydrological model was used to estimate catchment runoff and lake inflows based on the 1990s (baseline), 2040s, and 2090s periods. Average temperature and precipitation results from an ensemble of 12 Global Circulation Models based on the IPCC 4th Assessment Report A1B emissions scenario were used as input to TopNet. Linked hydropower lake water balance models were developed and used to simulate hydropower operations including discharge, hydroelectric power generation, and spill based on TopNet future inflow predictions, projected electricity demand, and lake storage and outflow characteristics. Our results indicate that annual lake inflows increase under future climate scenarios, but that there are seasonal effects with increasing flows in winter and early spring, and summer flows decreasing somewhat as a result of increasing temperatures and greater winter rain with less snow. Although overall hydropower generation can increase with the increasing flows and projected electricity demand, the seasonal changes result in demand being met in winter and spring with potential shortfalls in summer and autumn. Maximum annual generation can be achieved for some generating stations, but generation will decrease at other stations and more spill will likely be required through the 2090s because of the seasonal changes. Therefore flood and drought risk could also increase for downstream areas. Results also indicate that by the 2090s electricity demand could exceed generation capacity for these headwater lakes. Copyright © 2016 John Wiley & Sons, Ltd.  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