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   192361篇
  免费   18355篇
  国内免费   10656篇
电工技术   15710篇
技术理论   8篇
综合类   20165篇
化学工业   17669篇
金属工艺   7860篇
机械仪表   18756篇
建筑科学   20754篇
矿业工程   7093篇
能源动力   8031篇
轻工业   13641篇
水利工程   7705篇
石油天然气   8540篇
武器工业   2475篇
无线电   13936篇
一般工业技术   18788篇
冶金工业   7304篇
原子能技术   2653篇
自动化技术   30284篇
  2024年   793篇
  2023年   2367篇
  2022年   4770篇
  2021年   5539篇
  2020年   5927篇
  2019年   4903篇
  2018年   4880篇
  2017年   6037篇
  2016年   7276篇
  2015年   7685篇
  2014年   12304篇
  2013年   12261篇
  2012年   14326篇
  2011年   15670篇
  2010年   11290篇
  2009年   11513篇
  2008年   10856篇
  2007年   13089篇
  2006年   11383篇
  2005年   9524篇
  2004年   8017篇
  2003年   6887篇
  2002年   5578篇
  2001年   4623篇
  2000年   3952篇
  1999年   3259篇
  1998年   2784篇
  1997年   2356篇
  1996年   1964篇
  1995年   1618篇
  1994年   1454篇
  1993年   1075篇
  1992年   967篇
  1991年   711篇
  1990年   593篇
  1989年   527篇
  1988年   439篇
  1987年   291篇
  1986年   240篇
  1985年   227篇
  1984年   264篇
  1983年   246篇
  1982年   204篇
  1981年   106篇
  1980年   102篇
  1979年   68篇
  1978年   57篇
  1977年   55篇
  1976年   46篇
  1959年   32篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
煤气设施防腐实践及影响质量因素分析   总被引:1,自引:1,他引:0  
邱欣盛 《冶金动力》2002,(1):12-12,14
根据近几年三明钢铁公司煤气设施的防腐实践,就影响煤气设施的质量因素进行了分析。  相似文献   
102.
We present a data-driven dynamic coupling between discrete and continuous methods for tracking objects of high dofs, which overcomes the limitations of previous techniques. In our approach, two trackers work in parallel, and the coupling between them is based on the tracking error. We use a model-based continuous method to achieve accurate results and, in cases of failure, we re-initialize the model using our discrete tracker. This method maintains the accuracy of a more tightly coupled system, while increasing its efficiency. At any given frame, our discrete tracker uses the current and several previous frames to search into a database for the best matching solution. For improved robustness, object configuration sequences, rather than single configurations, are stored in the database. We apply our framework to the problem of 3D hand tracking from image sequences and the discrimination between fingerspelling and continuous signs in American Sign Language.  相似文献   
103.
Lennart Sjberg 《Displays》1987,8(4):210-212
A discussion of the factors involved in the subjective perception of television picture quality is presented. Much of the work in this field is cited, and it is concluded that future work needs to consider a broader range of variables than has been looked at so far.  相似文献   
104.
105.
通过对轴齿轮断口形貌、硬度测试及金相组织等试验进行分析表明,齿根处没有进行硬化处理造成齿根处抗疲劳性能不足是导致轴齿轮疲劳断裂的主要原因,另外齿根过渡处倒角过小,且存在纵向刀痕引起了较大应力集中也是导致轴齿轮疲劳断裂的原因。  相似文献   
106.
济钢350m^3高炉高富氧生产技术   总被引:1,自引:1,他引:0  
分析了济钢350m^3高炉高富氧对产量,理论燃烧温度,炉况顺行状况,焦比和生产效益的影响,高富氧可提高产量,但升高焦比和高炉理论燃烧温度,一定程度上影响高炉顺行,存在富氧效益最大化的适宜富氧率.高炉生产应低富氧高喷煤,根据钢目前的情况,富氧率经2%-3%为宜.  相似文献   
107.
针对天铁板坯连铸机一年多来发生的漏钢事故,分析了产生的原因,提出了预防改进的措施,对今后的生产有很好的指导意义。  相似文献   
108.
A method was developed to assess the heat insulation performance of intumescent coatings. The method consists of temperature measurements using the bench‐scaled experimental set‐up of a cone calorimeter and finite difference simulation to calculate the effective thermal conductivity dependent on time/temperature. This simulation procedure was also adapted to the small scale test furnace, in which the standard time–temperature curve is applied to a larger sample and thus which provides results relevant for approval. Investigations on temperature and calculated effective thermal conduction were performed on intumescent coatings in both experimental set‐ups using various coating thicknesses. The results correspond to each other as well as showing the limits of transferability between both fire tests. It is shown that bench‐scaled cone calorimeter tests are a valuable tool for assessing and predicting the performance of intumescent coatings in larger tests relevant for approval. The correlation fails for processes at surface temperatures above 750°C, which are not reached in the cone calorimeter, but are attained in the small scale furnace set‐up. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   
109.
This paper presents a new approach for using stereo and motion correspondences to solve the problem of tracking multiple independently moving features. In this approach, quantitative relational structure (QRS) is proposed as a framework for the integration of stereo–motion correspondences. The similarity function, tightly coupled to stereo and motion cues, is constructed on QRS, and then energy function E2 consisting of the similarity function is defined. The tracking problem can be converted into the maximization problem of the energy function E2. The stereo and motion correspondences that maximize E2 are recovered by applying an extended graduated assignment algorithm. The relaxation labeling method is also presented for the comparison with the proposed method. Experimental results are presented to illustrate the performance of the proposed method.  相似文献   
110.
We consider a stochastic control problem with linear dynamics with jumps, convex cost criterion, and convex state constraint, in which the control enters the drift, the diffusion, and the jump coefficients. We allow these coefficients to be random, and do not impose any Lp-bounds on the control.

We obtain a stochastic maximum principle for this model that provides both necessary and sufficient conditions of optimality. This is the first version of the stochastic maximum principle that covers the consumption–investment problem in which there are jumps in the price system.  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