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   1704篇
  免费   76篇
  国内免费   60篇
电工技术   17篇
综合类   82篇
化学工业   24篇
金属工艺   12篇
机械仪表   37篇
建筑科学   40篇
矿业工程   14篇
能源动力   12篇
轻工业   25篇
水利工程   2篇
石油天然气   11篇
武器工业   2篇
无线电   72篇
一般工业技术   62篇
冶金工业   8篇
原子能技术   6篇
自动化技术   1414篇
  2024年   1篇
  2023年   3篇
  2022年   7篇
  2021年   15篇
  2020年   23篇
  2019年   23篇
  2018年   19篇
  2017年   18篇
  2016年   28篇
  2015年   32篇
  2014年   58篇
  2013年   64篇
  2012年   41篇
  2011年   78篇
  2010年   64篇
  2009年   75篇
  2008年   95篇
  2007年   96篇
  2006年   108篇
  2005年   83篇
  2004年   83篇
  2003年   73篇
  2002年   74篇
  2001年   92篇
  2000年   69篇
  1999年   63篇
  1998年   54篇
  1997年   57篇
  1996年   40篇
  1995年   46篇
  1994年   40篇
  1993年   35篇
  1992年   33篇
  1991年   19篇
  1990年   22篇
  1989年   20篇
  1988年   4篇
  1987年   10篇
  1986年   8篇
  1985年   20篇
  1984年   12篇
  1983年   8篇
  1982年   6篇
  1981年   4篇
  1980年   5篇
  1979年   6篇
  1978年   2篇
  1977年   1篇
  1976年   3篇
排序方式: 共有1840条查询结果,搜索用时 15 毫秒
1.
Urban researchers have maintained a constant interest in the complexity and continuity of urban space usage. Some have applied actor–network theory (ANT) to investigate the heterogeneity of spaces and present them through the networks of their users’ activities. However, these accounts are predominantly limited in examining the extent to which these spaces may be heterogeneous when exploring such networks. This paper draws on recent ANT scholarship, which employs an ethnographic research conducted in a main park in a housing project at Dahiyat Al Hussein in Amman, Jordan. The findings describe the complex and unpredictable negotiations that occur within spaces by documenting the varieties and interrelations among user activity networks within this common and shared urban space. This research reveals the extent to which spaces, parks in this case, may be heterogeneous by unpacking their usage. The conclusions and insights assert the necessity of paying attention to design detail and creating designs that are responsive to evolving user activities.  相似文献   
2.
为了避免露天金属矿爆破后导致爆堆边缘矿石品位贫化损失,需要根据最低品位阈值重新计算矿岩边界,而影响矿岩边界发生改变因素众多,需要确定主要影响因素。因此,利用爆堆爆破前地形方向和爆堆地质数据,构建灰色关联-广义回归神经网络模型(GRA-GRNN)分析爆堆矿岩边界变化主要影响因素。首先对爆堆钻孔品位数据使用析取克里金法进行空间插值,并根据矿山工艺最低品位阈值提取爆破前的矿岩边界;其次,将爆破前后的数字DEM模型进行求差,求得爆破后的爆堆数字DEM模型,并构建爆破前后爆堆数字DEM模型空间分布椭圆,从而确定爆堆爆破后的水平形变方向;对影响爆堆爆破后形变的可能因素进行提取,并应用GRA-GRNN模型选取主要影响因素及对其强度进行分析,并将其结果与BP神经网络模型预测结果进行了对比。从实验结果可知,影响爆堆爆破后形变强度排前三的因素为:爆破前地形方向、爆孔排距和列距,强度分别为0.880、0.760和0.755,预测结果优于BP模型。  相似文献   
3.
The paper focuses on the adaptive relational association rule mining problem. Relational association rules represent a particular type of association rules which describe frequent relations that occur between the features characterizing the instances within a data set. We aim at re-mining an object set, previously mined, when the feature set characterizing the objects increases. An adaptive relational association rule method, based on the discovery of interesting relational association rules, is proposed. This method, called ARARM (Adaptive Relational Association Rule Mining) adapts the set of rules that was established by mining the data before the feature set changed, preserving the completeness. We aim to reach the result more efficiently than running the mining algorithm again from scratch on the feature-extended object set. Experiments testing the method's performance on several case studies are also reported. The obtained results highlight the efficiency of the ARARM method and confirm the potential of our proposal.  相似文献   
4.
This essay paper focuses on how the idea and use of technology is gradually reorganizing not only the structural arrangements but also redefining relationships and relational patterns. In particular reference to new technological applications and sites that are increasingly used by people for networking and bonding, there is a macro-discourse of being and staying connected through technology. Such platforms assume an easy access or an imagined availability of the other person at all times. Such availability also assumes psychological availability of the person, despite any personal circumstances he/she may be in. Experiencing the compressed space and time has given birth to the debate of quality of life and relations surrounding it vs. the constant flux of technology that restricts the psychological freedom while facilitating a structural freedom to communicate. Technology is an artifact that not only symbolizes values of ease and convenience but also has the potential to affect the deeper assumptions and values people hold about life and relationships. Thus, it mediates our personal, social and organizational realities, pushing us to live in dual worlds.  相似文献   
5.
In this paper, we propose a novel formulation extending convolutional neural networks (CNN) to arbitrary two-dimensional manifolds using orthogonal basis functions called Zernike polynomials. In many areas, geometric features play a key role in understanding scientific trends and phenomena, where accurate numerical quantification of geometric features is critical. Recently, CNNs have demonstrated a substantial improvement in extracting and codifying geometric features. However, the progress is mostly centred around computer vision and its applications where an inherent grid-like data representation is naturally present. In contrast, many geometry processing problems deal with curved surfaces and the application of CNNs is not trivial due to the lack of canonical grid-like representation, the absence of globally consistent orientation and the incompatible local discretizations. In this paper, we show that the Zernike polynomials allow rigourous yet practical mathematical generalization of CNNs to arbitrary surfaces. We prove that the convolution of two functions can be represented as a simple dot product between Zernike coefficients and the rotation of a convolution kernel is essentially a set of 2 × 2 rotation matrices applied to the coefficients. The key contribution of this work is in such a computationally efficient but rigorous generalization of the major CNN building blocks.  相似文献   
6.
7.
In order to identify the best porous materials for the cryogenic physisorption of hydrogen, high-throughput calculations are performed starting, i.e., from the collected information in crystallographic databases. However, these calculations, like molecular simulations, require specific training and significant computational cost. Herein, a relatively simple procedure is proposed to estimate and compare hydrogen uptakes at 77 K and pressure values from 40 bar starting from the porous properties of MOF materials, without involving simulation tools. This procedure uses definitions for adsorption and considers the adsorbed phase as an incompressible fluid whose pressure-density change is that for the liquid phase at 19 K. For the 7000 structures from the CoRE MOF database, the average error of the predictions is only of 1% from reference values at 100 bar, with an SD of ±8%. This accuracy is lower than that from simulation tools, but involving lower computational cost and training.  相似文献   
8.
Nanotechnology has arisen as a key player in the field of nanomedicine. Although the use of engineered nanoparticles is rapidly increasing, safety assessment is also important for the beneficial use of new nanomaterials. Considering that the experimental assessment of new nanomaterials is costly and laborious, in silico approaches hold promise. Several major challenges in nanotechnology indicate a need for nanoinformatics. New database initiatives such as ISA-TAB-Nano, caNanoLab, and Nanomaterial Registry will help in data sharing and developing data standards, and, as the amount of nanomaterials data grows, will provide a way to develop methods and tools specific to the nanolevel. In this review, we describe emerging databases and tools that should aid in the progress of nanotechnology research.  相似文献   
9.
大数据技术在主动配电网中的应用综述   总被引:1,自引:0,他引:1  
主动配电网实现主动运行和主动管理需要全景的配网状态数据。随着智能电网的建设,特别是用电采集系统、在线监控系统的实施和应用使电网公司的数据量达到PB级,进入大数据时代。如何高效利用这些数据实现与用户的互动,解决分布式能源消纳是当前的研究焦点。文章首先概述了当前主动配电网中的大数据类型及特点;然后列举了当前在工业产业界广泛应用的大数据技术,分析了这些技术在主动配电网中可能的应用及挑战;最后结合主动配电网在能量优化调度、状态分析评估、保护控制及需求侧管理方面的应用需求,对大数据技术可能的应用场景做了展望。  相似文献   
10.
This paper proposes an integrated approach to identify, evaluate and improve the potential failures in a service setting. This integrated approach combines Fuzzy cost‐based service‐specific FMEA (FCS‐FMEA), Grey Relational Analysis (GRA) and profitability theory for better prioritization of the service failures by considering cost as an important issue and using the profitability theory in a way that the corrective actions costs are taken into account. Considering profitability with FCS‐FMEA and GRA reduces the losses caused by failure occurrence. Besides, a maximization linear mathematical problem is used to select the best mix of failures to be repaired. We apply our approach to an academic example concerning the potential failures diagnosis of the Internal Medicine service of a hospital located in Seoul, Korea. We applied our approach and solved the associated maximization problem by a commercial solver, producing an optimal solution which indicates the most convenient mix of failures to be repaired by considering available budget. Copyright © 2013 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