全文获取类型
收费全文 | 11410篇 |
免费 | 822篇 |
国内免费 | 100篇 |
专业分类
电工技术 | 229篇 |
综合类 | 46篇 |
化学工业 | 3095篇 |
金属工艺 | 250篇 |
机械仪表 | 448篇 |
建筑科学 | 427篇 |
矿业工程 | 26篇 |
能源动力 | 748篇 |
轻工业 | 1108篇 |
水利工程 | 202篇 |
石油天然气 | 163篇 |
武器工业 | 5篇 |
无线电 | 1191篇 |
一般工业技术 | 1950篇 |
冶金工业 | 315篇 |
原子能技术 | 81篇 |
自动化技术 | 2048篇 |
出版年
2024年 | 50篇 |
2023年 | 232篇 |
2022年 | 424篇 |
2021年 | 704篇 |
2020年 | 632篇 |
2019年 | 760篇 |
2018年 | 869篇 |
2017年 | 832篇 |
2016年 | 809篇 |
2015年 | 490篇 |
2014年 | 804篇 |
2013年 | 1208篇 |
2012年 | 774篇 |
2011年 | 873篇 |
2010年 | 567篇 |
2009年 | 516篇 |
2008年 | 322篇 |
2007年 | 250篇 |
2006年 | 191篇 |
2005年 | 131篇 |
2004年 | 128篇 |
2003年 | 88篇 |
2002年 | 80篇 |
2001年 | 53篇 |
2000年 | 45篇 |
1999年 | 44篇 |
1998年 | 44篇 |
1997年 | 43篇 |
1996年 | 45篇 |
1995年 | 40篇 |
1994年 | 27篇 |
1993年 | 24篇 |
1992年 | 21篇 |
1991年 | 21篇 |
1990年 | 23篇 |
1989年 | 17篇 |
1988年 | 13篇 |
1987年 | 10篇 |
1986年 | 14篇 |
1985年 | 20篇 |
1984年 | 22篇 |
1983年 | 20篇 |
1982年 | 9篇 |
1981年 | 5篇 |
1980年 | 6篇 |
1979年 | 9篇 |
1978年 | 8篇 |
1977年 | 6篇 |
1976年 | 5篇 |
1973年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
101.
The design of systems for dynamic response may involve constraints that need to be satisfied over an entire time interval
or objective functions evaluated over the interval. Efficiently performing the constrained optimization is challenging, since
the typical response is implicitly linked to the design variables through a numerical integration of the governing differential
equations. Evaluating constraints is costly, as is the determination of sensitivities to variations in the design variables.
In this paper, we investigate the application of a temporal spectral element method to the optimization of transient and time-periodic
responses of fundamental engineering systems. Through the spectral discretization, the response is computed globally, thereby
enabling a more explicit connection between the response and design variables and facilitating the efficient computation of
response sensitivities. Furthermore, the response is captured in a higher order manner to increase analysis accuracy. Two
applications of the coupling of dynamic response optimization with the temporal spectral element method are demonstrated.
The first application, a one-degree-of-freedom, linear, impact absorber, is selected from the auto industry, and tests the
ability of the method to treat transient constraints over a large-time interval. The second application, a related mass-spring-damper
system, shows how the method can be used to obtain work and amplitude optimal time-periodic control force subject to constraints
over a periodic time interval.
This research was performed while the first author held a National Research Council Research Associateship Award at the Air
Force Research Laboratory.
An early version of this paper was presented at the 46th AIAA Aerospace Sciences Meeting and Exhibit, Jan 7–10, 2008, Reno,
Nevada. 相似文献
102.
Omidinasab Fereydoon Sahraei Moghadam Amirhosein Dowlatshahi Mohammad Bagher 《Neural computing & applications》2023,35(11):8487-8503
Neural Computing and Applications - In order to attain sustainable development, recycled concrete aggregates (RCAs) are increasingly utilized in civil engineering projects. Therefore, it is vital... 相似文献
103.
Mohammad Farhan Tanzim Nuno Fortunato Ilias Samathrakis Ruiwen Xie Ingo Opahle Oliver Gutfleisch Hongbin Zhang 《Advanced functional materials》2023,33(28):2214967
All-d Heuslers are a category of novel compounds combining versatile functionalities such as caloric responses and spintronics with enhanced mechanical properties. Despite the promising transport properties (anomalous Hall (AHC) and anomalous Nernst (ANC) conductivities) shown in the conventional Co2XY Heuslers with p-d hybridization, the all-d Heuslers with only d-d hybridization open a new horizon to search for new candidates with outstanding transport properties. In this work, the AHC and ANC are evaluated for thermodynamically stable ferro/ferri-magnetic all-d-metal regular Heusler compounds based on high-throughput first-principles calculations. It is observed that quite a few materials exhibit giant AHCs and ANCs, such as cubic Re2TaMn with an AHC of 2011 S cm-1, and tetragonal Pt2CrRh with an AHC of 1966 S cm-1 and an ANC of 7.50 A m-1K-1. Comprehensive analysis on the electronic structure reveals that the high AHC can be attributed to the occurrence of the Weyl nodes or gapped nodal lines in the neighborhood of the Fermi level. The correlations between such transport properties and the number of valence electrons are also thoroughly investigated, which provides a practical guidance to tailor AHC and ANC via chemical doping for transverse thermoelectric applications. 相似文献
104.
Mohibullah Khan Ata Ullah Isra Naz Sajjad Haider Nz Jhanji Mohammad Shorfuzzaman Mehedi Masud 《计算机系统科学与工程》2023,46(1):461-473
The deep learning model encompasses a powerful learning ability that integrates the feature extraction, and classification method to improve accuracy. Convolutional Neural Networks (CNN) perform well in machine learning and image processing tasks like segmentation, classification, detection, identification, etc. The CNN models are still sensitive to noise and attack. The smallest change in training images as in an adversarial attack can greatly decrease the accuracy of the CNN model. This paper presents an alpha fusion attack analysis and generates defense against adversarial attacks. The proposed work is divided into three phases: firstly, an MLSTM-based CNN classification model is developed for classifying COVID-CT images. Secondly, an alpha fusion attack is generated to fool the classification model. The alpha fusion attack is tested in the last phase on a modified LSTM-based CNN (CNN-MLSTM) model and other pre-trained models. The results of CNN models show that the accuracy of these models dropped greatly after the alpha-fusion attack. The highest F1 score before the attack was achieved is 97.45 And after the attack lowest F1 score recorded is 22%. Results elucidate the performance in terms of accuracy, precision, F1 score and Recall. 相似文献
105.
Adnan Hasan Bdair Aighuraibawi Selvakumar Manickam Rosni Abdullah Zaid Abdi Alkareem Alyasseri Ayman Khallel Dilovan Asaad Zebari Hussam Mohammed Jasim Mazin Mohammed Abed Zainb Hussein Arif 《计算机系统科学与工程》2023,47(1):553-574
Internet Protocol version 6 (IPv6) is the latest version of IP that goal to host 3.4 × 1038 unique IP addresses of devices in the network. IPv6 has introduced new features like Neighbour Discovery Protocol (NDP) and Address Auto-configuration Scheme. IPv6 needed several protocols like the Address Auto-configuration Scheme and Internet Control Message Protocol (ICMPv6). IPv6 is vulnerable to numerous attacks like Denial of Service (DoS) and Distributed Denial of Service (DDoS) which is one of the most dangerous attacks executed through ICMPv6 messages that impose security and financial implications. Therefore, an Intrusion Detection System (IDS) is a monitoring system of the security of a network that detects suspicious activities and deals with a massive amount of data comprised of repetitive and inappropriate features which affect the detection rate. A feature selection (FS) technique helps to reduce the computation time and complexity by selecting the optimum subset of features. This paper proposes a method for detecting DDoS flooding attacks (FA) based on ICMPv6 messages using a Binary Flower Pollination Algorithm (BFPA-FA). The proposed method (BFPA-FA) employs FS technology with a support vector machine (SVM) to identify the most relevant, influential features. Moreover, The ICMPv6-DDoS dataset was used to demonstrate the effectiveness of the proposed method through different attack scenarios. The results show that the proposed method BFPA-FA achieved the best accuracy rate (97.96%) for the ICMPv6 DDoS detection with a reduced number of features (9) to half the total (19) features. The proven proposed method BFPA-FA is effective in the ICMPv6 DDoS attacks via IDS. 相似文献
106.
Sarune Daskeviciute-Geguziene Yi Zhang Kasparas Rakstys Chuanxiao Xiao Jianxing Xia Zhiheng Qiu Maryte Daskeviciene Tomas Paskevicius Vygintas Jankauskas Abdullah M. Asiri Vytautas Getautis Mohammad Khaja Nazeeruddin 《Advanced functional materials》2023,33(1):2208317
In this study, a series of donor–acceptor–donor (D-A-D) type small molecules based on the fluorene and diphenylethenyl enamine units, which are distinguished by different acceptors, as holetransporting materials (HTMs) for perovskite solar cells is presented. The incorporation of the malononitrile acceptor units is found to be beneficial for not only carrier transportation but also defects passivation via Pb–N interactions. The highest power conversion efficiency of over 22% is achieved on cells based on V1359, which is higher than that of spiro-OMeTAD under identical conditions. This st shows that HTMs prepared via simplified synthetic routes are not only a low-cost alternative to spiro-OMeTAD but also outperform in efficiency and stability state-of-art materials obtained via expensive cross-coupling methods. 相似文献
107.
Seyed Hamid Hosseini Mohammad Saleh Tavazoei Nikolay V. Kuznetsov 《Asian journal of control》2023,25(3):1866-1876
This paper deals with defining the concept of agent-based time delay margin and computing its value in multi-agent systems controlled by event-triggered based controllers. The agent-based time delay margin specifying the time delay tolerance of each agent for ensuring consensus in event-triggered controlled multi-agent systems can be considered as complementary for the concept of (network) time delay margin, which has been previously introduced in some literature. In this paper, an event-triggered control method for achieving consensus in multi-agent systems with time delay is considered. It is shown that the Zeno behavior is excluded by applying this method. Then, in a multi-agent system controlled by the considered event-triggered method, the concept of agent-based time delay margin in the presence of a fixed network delay is defined. Moreover, an algorithm for computing the value of the time delay margin for each agent is proposed. Numerical simulation results are also provided to verify the obtained theoretical results. 相似文献
108.
Mahdikhah V. Ataie A. Akbari Moayyer H. Molaei Mohammad Jafar Babaei A. 《Journal of Electroceramics》2022,48(1):51-66
Journal of Electroceramics - In this research, hard/soft CoFe2O4/Ni magnetic nanocomposite samples with different concentrations of Ni were successfully produced by a two-step mechanical alloying... 相似文献
109.
Journal of Computational Electronics - In this study, the electronic transport properties of 4,6-bis(4-nitrophenyl)-2-phenyl-3,5-diaza-bicyclo[3.1.0]hex-2-ene (as a bicyclic aziridine) have been... 相似文献
110.
Analog Integrated Circuits and Signal Processing - A new structure for improving the performance of recycling folded cascode (RFC) operational transconductance amplifier (OTA) is presented. The... 相似文献