全文获取类型
收费全文 | 42682篇 |
免费 | 2588篇 |
国内免费 | 990篇 |
专业分类
电工技术 | 757篇 |
综合类 | 618篇 |
化学工业 | 1288篇 |
金属工艺 | 537篇 |
机械仪表 | 716篇 |
建筑科学 | 430篇 |
矿业工程 | 78篇 |
能源动力 | 1336篇 |
轻工业 | 239篇 |
水利工程 | 57篇 |
石油天然气 | 55篇 |
武器工业 | 9篇 |
无线电 | 7954篇 |
一般工业技术 | 3346篇 |
冶金工业 | 139篇 |
原子能技术 | 150篇 |
自动化技术 | 28551篇 |
出版年
2024年 | 32篇 |
2023年 | 736篇 |
2022年 | 1244篇 |
2021年 | 1657篇 |
2020年 | 1617篇 |
2019年 | 1295篇 |
2018年 | 1523篇 |
2017年 | 2934篇 |
2016年 | 3122篇 |
2015年 | 2453篇 |
2014年 | 3918篇 |
2013年 | 3125篇 |
2012年 | 2607篇 |
2011年 | 2582篇 |
2010年 | 2198篇 |
2009年 | 2525篇 |
2008年 | 1598篇 |
2007年 | 2168篇 |
2006年 | 1901篇 |
2005年 | 1213篇 |
2004年 | 744篇 |
2003年 | 757篇 |
2002年 | 778篇 |
2001年 | 715篇 |
2000年 | 536篇 |
1999年 | 587篇 |
1998年 | 342篇 |
1997年 | 204篇 |
1996年 | 171篇 |
1995年 | 111篇 |
1994年 | 93篇 |
1993年 | 93篇 |
1992年 | 81篇 |
1991年 | 71篇 |
1990年 | 61篇 |
1989年 | 59篇 |
1988年 | 39篇 |
1987年 | 37篇 |
1986年 | 39篇 |
1985年 | 56篇 |
1984年 | 45篇 |
1983年 | 37篇 |
1982年 | 24篇 |
1981年 | 20篇 |
1980年 | 19篇 |
1979年 | 15篇 |
1978年 | 18篇 |
1977年 | 21篇 |
1976年 | 18篇 |
1975年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
12.
Kirti M. Yenkie Jean Pimentel Ákos Orosz Heriberto Cabezas Ferenc Friedler 《American Institute of Chemical Engineers》2021,67(7):e17253
Wastewater treatment consists of three or four sequential stages: preliminary, primary, secondary, and tertiary. Each stage can comprise multiple alternative technologies that can perform the same tasks with different efficiencies, operating times, and costs. Thus, we propose a systematic approach for designing wastewater treatment networks by utilizing principles of mathematical modeling and generating an exhaustive enumeration of all the possible technologies and their connections during the early stages of designing a treatment facility. Some of these structures are nonintuitive and include recycling, reprocessing, bypasses, and multiple technologies in parallel or series to remove the same contaminant. The nonintuitive structures with multiple technologies may provide a measure of resilience compared to typical heuristic designs. Thus, the combination of P-graph methodology and the sequence of treatment technologies predicted via the optimization algorithm from the maximal structure is based on holistic considerations and does not lead to suboptimal solutions. 相似文献
13.
Mahantesh H. M. Nageswara Guptha M. Hema M. S. 《Wireless Personal Communications》2021,120(3):2349-2365
Wireless Personal Communications - 2In Software Defined Network based Internet of Things (SDN-IoT), the path selected for forwarding the packets as per rules, should be Quality of Service (QoS)... 相似文献
14.
MiE is a facial involuntary reaction that reflects the real emotion and thoughts of a human being. It is very difficult for a normal human to detect a Micro-Expression (MiE), since it is a very fast and local face reaction with low intensity. As a consequence, it is a challenging task for researchers to build an automatic system for MiE recognition. Previous works for MiE recognition have attempted to use the whole face, yet a facial MiE appears in a small region of the face, which makes the extraction of relevant features a hard task. In this paper, we propose a novel deep learning approach that leverages the locality aspect of MiEs by learning spatio-temporal features from local facial regions using a composite architecture of Convolutional Neural Network (CNN) and Long Short Term Memory (LSTM). The proposed solution succeeds to extract relevant local features for MiEs recognition. Experimental results on benchmark datasets demonstrate the highest recognition accuracy of our solution with respect to state-of-the-art methods. 相似文献
15.
Kumar S. Ganesh Sridhar S. S. Hussain Azham Manikanthan S. V. Padmapriya T. 《Multimedia Tools and Applications》2022,81(7):9091-9109
Multimedia Tools and Applications - Discovering the relevant web services for specific applications in the dynamically changing business world becomes very critical. Researchers have used many... 相似文献
16.
Ali Farman Ali Zulfiqar Li Bing-Zhao Qamar Sadia Nazeer Amna Riaz Saba Khan Muhammad Asif Fayyaz Rabia Nawaz Abbasi Javeria 《Water Resources Management》2022,36(9):2989-3005
Water Resources Management - Drought is recurrently occurring in many parts of the globe. In contrast to other natural hazards, drought has complex climatic characteristics. Several environmental... 相似文献
17.
Singh Nalin Rathore Santosh Singh Kumar Sandeep 《Multimedia Tools and Applications》2022,81(27):38887-38919
Multimedia Tools and Applications - The video surveillance activity generates a vast amount of data, which can be processed to detect miscreants. The task of identifying and recognizing an object... 相似文献
18.
Efficient electricity price forecasting plays a significant role in our society. In this paper, a novel influencer-defaulter mutation (IDM) mutation operator has been proposed. The IDM operator has been combined with six well-known optimization algorithms to create mutated optimization algorithms whose performance has been tested on twenty-four standard benchmark functions. Further, the artificial neural network is integrated with mutated optimization algorithms to solve the electricity price prediction problem. The policymakers can identify appropriate variables based on the predicted prices to help future market planning. The statistical results prove the efficacy of the IDM operator on the recent optimization algorithms. 相似文献
19.
《Journal of the European Ceramic Society》2022,42(2):453-461
A few compositions of the system Sr2Mn1-xSnxO4 (x = 0.0, 0.3, 0.5) were synthesized in the air by the solid-state ceramic route. A change in the sign (positive to negative) of the permittivity above a particular temperature (TC) is observed at all the measured frequencies. The negative permittivity was analyzed by the Drude-Lorentz model. It was found that negative permittivity is caused by the plasma oscillations of thermally excited free charge carriers. Analysis of XPS spectra confirmed the presence of mixed-valence states of both Mn (Mn4+ and Mn3+) and Sn (Sn4+ and Sn2+) ions. The UV–vis.-IR spectroscopy results indicated generation of a large number of defect states in the forbidden bandgap region of Sr2MnO4 on the substitution of Sn at Mn site. Synthesized samples are promising metamaterials for radio frequency (10 Hz -2 MHz) region applications due to the high-temperature plasmonic behavior. 相似文献
20.
Tuladhar Sanira Alsadoon Abeer Prasad P. W. C. Ali Akbas Ezaldeen Alrubaie Ahmad 《Multimedia Tools and Applications》2022,81(17):23845-23865
Multimedia Tools and Applications - Gastrointestinal stromal tumor is one of the critical tumors that doctors do not suggest to get frequent endoscopy, so there is a need for a diagnosis system... 相似文献