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   26633篇
  免费   2216篇
  国内免费   1180篇
电工技术   1462篇
技术理论   3篇
综合类   1669篇
化学工业   4444篇
金属工艺   1769篇
机械仪表   1649篇
建筑科学   2342篇
矿业工程   741篇
能源动力   716篇
轻工业   1686篇
水利工程   441篇
石油天然气   1475篇
武器工业   206篇
无线电   3087篇
一般工业技术   3401篇
冶金工业   1133篇
原子能技术   258篇
自动化技术   3547篇
  2024年   127篇
  2023年   444篇
  2022年   773篇
  2021年   1144篇
  2020年   875篇
  2019年   661篇
  2018年   777篇
  2017年   832篇
  2016年   762篇
  2015年   983篇
  2014年   1196篇
  2013年   1499篇
  2012年   1626篇
  2011年   1733篇
  2010年   1609篇
  2009年   1490篇
  2008年   1426篇
  2007年   1449篇
  2006年   1391篇
  2005年   1299篇
  2004年   895篇
  2003年   792篇
  2002年   802篇
  2001年   634篇
  2000年   727篇
  1999年   744篇
  1998年   624篇
  1997年   494篇
  1996年   506篇
  1995年   393篇
  1994年   325篇
  1993年   254篇
  1992年   208篇
  1991年   136篇
  1990年   88篇
  1989年   91篇
  1988年   73篇
  1987年   41篇
  1986年   34篇
  1985年   16篇
  1984年   16篇
  1983年   11篇
  1982年   10篇
  1981年   7篇
  1980年   8篇
  1979年   1篇
  1978年   1篇
  1970年   1篇
  1969年   1篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
171.
Computational Visual Media - The exact shape of intracranial aneurysms is critical in medical diagnosis and surgical planning. While voxel-based deep learning frameworks have been proposed for this...  相似文献   
172.
Wang  Zongshan  Ding  Hongwei  Li  Bo  Bao  Liyong  Yang  Zhijun  Liu  Qianlin 《Wireless Personal Communications》2022,125(3):2167-2200

Maximizing network lifetime is the main goal of designing a wireless sensor network. Clustering and routing can effectively balance network energy consumption and prolong network lifetime. This paper presents a novel cluster-based routing protocol called EECRAIFA. In order to select the optimal cluster heads, Self-Organizing Map neural network is used to perform preliminary clustering on the network nodes, and then the relative reasonable level of the cluster, the cluster head energy, the average distance within the cluster and other factors are introduced into the firefly algorithm (FA) to optimize the network clustering. In addition, the concept of decision domain is introduced into the FA to further disperse cluster heads and form reasonable clusters. In the inter-cluster routing stage, the inter-cluster routing is established by an improved ant colony optimization (ACO). Considering factors such as the angle, distance and energy of the node, the heuristic function is improved to make the selection of the next hop more targeted. In addition, the coefficient of variation in statistics is introduced into the process of updating pheromones, and the path is optimized by combining energy and distance. In order to further improve the network throughput, a polling control mechanism based on busy/idle nodes is introduced during the intra-cluster communication phase. The simulation experiment results prove that under different application scenarios, EECRAIFA can effectively balance the network energy consumption, extend the network lifetime, and improve network throughput.

  相似文献   
173.
Herein, a trimetallic Ni–Co–Zn perovskite fluoride (ABF3) (denoted as KNCZF) electrode material is explored for advanced aqueous supercabatteries (ASCBs), with KNCZF and activated carbon–FeBiCu@reduced graphene oxides (AC–FeBiCu@rGO) as cathode and anode, respectively, which outperform aqueous supercapacitors (ASCs) and batteries (ABs) with AC and FeBiCu@rGO anodes because of the synergistic effect of pseudocapacitive (KNCZF), capacitive (AC), and faradaic (FeBiCu@rGO) responses. One of the important findings is that the KNCZF shows a typical bulk phase conversion mechanism for charge storage in the alkaline media with the transition of ABF3 perovskite nanocrystals into amorphous metal oxides/(oxy)hydroxides nanosheets, showing the redox-active and redox-inert roles for the Ni/Co and Zn species, respectively, which can be deduced by various ex-situ techniques. Another interesting finding is that the redox-inert Zn species largely enhance the activity of Ni/Co redox-active species in the ABF3 materials, mainly owing to the promotion of surface electroactive sites, adsorption of OH?, and charge transfer of surface Ni/Co atoms by Zn-doping, which can be proved by ex-situ characterizations and theoretical calculations. Overall, this study reveals the structure–activity relationship and charge storage mechanisms of Zn-doping ABF3 materials for advanced ASCBs, showing a great impact on developing advanced electrochemical energy storage.  相似文献   
174.
Chen  Yun  Li  Huaizhong  Hou  Liang  Bu  Xiangjian  Ye  Shaogan  Chen  Ding 《Journal of Intelligent Manufacturing》2022,33(1):121-135
Journal of Intelligent Manufacturing - Chatter in machining results in poor workpiece surface quality and short tool life. An accurate and reliable chatter detection method is needed before its...  相似文献   
175.
Yu  Bo  Du  Haibo  Ding  Lijian  Wu  Di  Li  Hua 《Neural computing & applications》2022,34(7):5107-5117
Neural Computing and Applications - In this paper, the problem of attitude stabilization control of spacecraft under angular velocity constraint is investigated. A state-constrained finite-time...  相似文献   
176.
Mental workload is considered to be strongly linked to human performance, and the ability to measure it accurately is key for balancing human health and work. In this study, brain signals were elicited by mental arithmetic tasks of varying difficulty to stimulate different levels of mental workload. In addition, a finite impulse response (FIR) filter, independent component analysis (ICA), and multiple artifact rejection algorithms (MARAs) were used to filter event-related potentials (ERPs). Then, the data consisting of ERPs, subjective ratings of mental workload, and task performance, were analyzed through the use of variance and Spearman’s correlation during a simulated computer task. We found that participants responded faster and performed better in the easy task condition, followed by the medium and high-difficulty conditions, which verifies the validity of the ERP filtering. Moreover, larger P2 and P3 waveforms were evoked as the task difficulty increased, and a higher task difficulty elicited a more enhanced N300. Correlation analysis revealed a negative relationship between the amplitude of P3 and the subjective ratings, and a positive relationship between the P3 amplitude and accuracy. The results presented in this paper demonstrate that a combination of FIR, ICA, and MARA methods can filter ERPs in the non-invasive real-time measurement of workload. Additionally, frontocentral P2, N3, and parietal P3 components showed differences between genders. The proposed measurement of mental workload can be useful for real-time identification of mental states and can be applied to human–computer interaction in the future.  相似文献   
177.

This paper aims to improve the quality and efficiency of talent cultivation in colleges and universities and effectively analyze and count the number of talents. The cultivation of computer professionals in higher vocational education is taken as the research object. First, a talent cultivation information system for colleges and universities is developed, using deep learning neural networks and data mining algorithms and introducing recurrent neural networks (RNN) and a fusion attention model. With a view to the needs of employment forms and employment data, a diversified talent demand cultivation program is formulated. Based on this, an efficient talent cultivation quality indicator system is established through analyzing talent cultivation data in higher vocational education. Finally, the effectiveness of the system is verified by the performance analysis. The results show an average prediction accuracy for the proposed Attention RNN Word2 algorithm of 80.61%, which is significantly higher than achieved by the latest research algorithm model, and the talent training has a classification accuracy of 82%. This model is not only feasible for categorizing computer professional personnel cultivation but can also accurately reflect problems arising in personnel cultivation, and the results are made obvious by visualization. To sum up, the system reported here can give an intuitive demonstration of the quality of computer professional personnel cultivation in higher vocational education. This research provides a theoretical basis for related research into the cultivation of computer professionals in higher vocational education for application in industry, universities, and research.

  相似文献   
178.
Huang  Nana  Hu  Ruimin  Xiong  Mingfu  Peng  Xiaoran  Ding  Hongwei  Jia  Xiaodong  Zhang  Lingkun 《Neural computing & applications》2022,34(19):16643-16654
Neural Computing and Applications - Existing sequential recommendation methods focus on modeling the temporal relationships of users’ historical behaviors and excel in exploiting users’...  相似文献   
179.
测量不确定度是对测量结果的质量的定量评定,意味着对测量结果可信性、有效性的怀疑程度或不肯定程度。本文依据JJF1059-1999《测量不确定度的评定和表示》,计算实验过程中各因素引入的不确定度,建立葡萄酒中总酸的测定不确定度评定方法。  相似文献   
180.
An analytical solution for simply supported layered plates with viscoelastic interlayers under a transverse load is proposed. The deformation of each plate layer is described by the exact three-dimensional elasticity equations. The viscoelastic property of interlayer is simulated by the generalized Maxwell model. The constitutive relation of the interlayer is simplified by the quasi-elastic approximation, which significantly simplifies the analytical process. The solution of stress and displacement fields with undetermined coefficients is derived by solving a group of ordinary differential equations. The undetermined coefficients can be efficiently deduced by using the recursive matrix technique for the plate with any number of layers. The practical convergence is observed during numerical tests. The comparison analysis indicates that the present solution has a close agreement with the finite element solution. However, the solution based on the Mindlin–Reissner hypothesis is significantly different from the present solution for thick plates. Finally, the effect of interlayer thickness on stress and displacement distributions of a five-layer plate is discussed in detail.  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