全文获取类型
收费全文 | 4824篇 |
免费 | 154篇 |
国内免费 | 5篇 |
专业分类
电工技术 | 66篇 |
综合类 | 1篇 |
化学工业 | 868篇 |
金属工艺 | 76篇 |
机械仪表 | 81篇 |
建筑科学 | 197篇 |
矿业工程 | 15篇 |
能源动力 | 83篇 |
轻工业 | 533篇 |
水利工程 | 32篇 |
石油天然气 | 17篇 |
无线电 | 523篇 |
一般工业技术 | 840篇 |
冶金工业 | 1148篇 |
原子能技术 | 25篇 |
自动化技术 | 478篇 |
出版年
2023年 | 34篇 |
2022年 | 26篇 |
2021年 | 110篇 |
2020年 | 70篇 |
2019年 | 82篇 |
2018年 | 80篇 |
2017年 | 84篇 |
2016年 | 77篇 |
2015年 | 76篇 |
2014年 | 104篇 |
2013年 | 252篇 |
2012年 | 172篇 |
2011年 | 216篇 |
2010年 | 154篇 |
2009年 | 138篇 |
2008年 | 142篇 |
2007年 | 161篇 |
2006年 | 152篇 |
2005年 | 145篇 |
2004年 | 115篇 |
2003年 | 114篇 |
2002年 | 116篇 |
2001年 | 92篇 |
2000年 | 107篇 |
1999年 | 89篇 |
1998年 | 274篇 |
1997年 | 180篇 |
1996年 | 154篇 |
1995年 | 109篇 |
1994年 | 95篇 |
1993年 | 111篇 |
1992年 | 55篇 |
1991年 | 47篇 |
1990年 | 60篇 |
1989年 | 76篇 |
1988年 | 77篇 |
1987年 | 57篇 |
1986年 | 58篇 |
1985年 | 54篇 |
1984年 | 39篇 |
1983年 | 43篇 |
1982年 | 45篇 |
1981年 | 51篇 |
1980年 | 40篇 |
1979年 | 37篇 |
1978年 | 30篇 |
1977年 | 65篇 |
1976年 | 79篇 |
1975年 | 37篇 |
1974年 | 35篇 |
排序方式: 共有4983条查询结果,搜索用时 843 毫秒
1.
Zenan Yu Julian Moore Jean Calderon Lei Zhai Jayan Thomas 《Small (Weinheim an der Bergstrasse, Germany)》2015,11(39):5289-5295
Cable‐shaped supercapacitors (SCs) have recently aroused significant attention due to their attractive properties such as small size, lightweight, and bendability. Current cable‐shaped SCs have symmetric device configuration. However, if an asymmetric design is used in cable‐shaped supercapacitors, they would become more attractive due to broader cell operation voltages, which results in higher energy densities. Here, a novel coil‐type asymmetric supercapacitor electrical cable (CASEC) is reported with enhanced cell operation voltage and extraordinary mechanical‐electrochemical stability. The CASECs show excellent charge–discharge profiles, extraordinary rate capability (95.4%), high energy density (0.85 mWh cm−3), remarkable flexibility and bendability, and superior bending cycle stability (≈93.0% after 4000 cycles at different bending states). In addition, the CASECs not only exhibit the capability to store energy but also to transmit electricity simultaneously and independently. The integrated electrical conduction and storage capability of CASECS offer many potential applications in solar energy storage and electronic gadgets. 相似文献
2.
Daniel T. Payne Mandeep K. Chahal V clav B&rcaron ezina Whitney A. Webre Katsuhiko Ariga Francis D Souza Jan Labuta Jonathan P. Hill 《Frontiers of Chemical Science and Engineering》2020,14(1):28
Chiral 1,1’-binaphthyl-linked diporphyrin ‘tweezers’ (R)-1/(S)-1 and the corresponding zinc(II) complexes (R)-2/(S)-2 were prepared as chiral host molecules, and their utility for chiral analyses (especially enantiomeric excess (ee) determinations) were evaluated. Tris(1-n-dodecyl)porphyrins were used for the first time as the interacting units. Host capabilities of the diporphyrin tweezers were investigated by titrations with (R,R)- and (S,S)-cyclohexane-1,2-diamine (CHDA). The host molecules could be used as multichannel probes of ee by using UV-vis, circular dichroism (CD), fluorescence emission and 1H nuclear magnetic resonance (1H-NMR) methods. Chiral configurations could also be differentiated using CD or 1H-NMR spectroscopy. All three optical techniques give good resolution of ee with reasonable sensitivity considering the low concentrations used (ca. 10−6 mol·L−1). The ee determination of CHDA enantiomers using NMR spectroscopy is also possible because of the reasonably well separated resonances in the case of (R,R)- and (S,S)-CHDA. Non-metallated (R)-1/(S)-1 hosts could not be used to detect chiral information in a strongly acidic chiral guest. This work demonstrates the utility of 1,1’-binapthyl-linked chiral hosts for chiral analysis of ditopically interacting enantiomers. 相似文献
3.
4.
Kooij Julian F. P. Flohr Fabian Pool Ewoud A. I. Gavrila Dariu M. 《International Journal of Computer Vision》2019,127(3):239-262
International Journal of Computer Vision - Anticipating future situations from streaming sensor data is a key perception challenge for mobile robotics and automated vehicles. We address the problem... 相似文献
5.
Juana Maria de Lourdes Medina-Contreras Patrick Mailloux-Salinas Juventino III Colado-Velazquez Norma Leticia Gomez Viquez Gómez-Viquez Rodrigo Velázquez-Espejel Ana del Carmen Susunaga-Notario David Julian Arias-Chávez Guadalupe Bravo 《Journal of the science of food and agriculture》2020,100(7):3212-3219
6.
Aleksandra Czumaj Sylwia Szrok-Jurga Areta Hebanowska Jacek Turyn Julian Swierczynski Tomasz Sledzinski Ewa Stelmanska 《International journal of molecular sciences》2020,21(23)
The importance of coenzyme A (CoA) as a carrier of acyl residues in cell metabolism is well understood. Coenzyme A participates in more than 100 different catabolic and anabolic reactions, including those involved in the metabolism of lipids, carbohydrates, proteins, ethanol, bile acids, and xenobiotics. However, much less is known about the importance of the concentration of this cofactor in various cell compartments and the role of altered CoA concentration in various pathologies. Despite continuous research on these issues, the molecular mechanisms in the regulation of the intracellular level of CoA under pathological conditions are still not well understood. This review summarizes the current knowledge of (a) CoA subcellular concentrations; (b) the roles of CoA synthesis and degradation processes; and (c) protein modification by reversible CoA binding to proteins (CoAlation). Particular attention is paid to (a) the roles of changes in the level of CoA under pathological conditions, such as in neurodegenerative diseases, cancer, myopathies, and infectious diseases; and (b) the beneficial effect of CoA and pantethine (which like CoA is finally converted to Pan and cysteamine), used at pharmacological doses for the treatment of hyperlipidemia. 相似文献
7.
8.
Even though reverberation chambers have been used primarily for radiated immunity testing, they are reciprocal devices that are equally applicable for radiated emissions testing. This short paper presents the theory for radiated emissions testing and uses electromagnetic reciprocity theory to demonstrate the link between radiated emissions and immunity testing. 相似文献
9.
Crosstalk between microstrip transmission lines 总被引:1,自引:0,他引:1
Hill D.A. Cavcey K.H. Johnk R.T. 《Electromagnetic Compatibility, IEEE Transactions on》1994,36(4):314-321
Methods for prediction of crosstalk between microstrip transmission lines are reviewed and simplified for the weak-coupling case. Classical coupled transmission line theory is used for uniform lines, and potential and induced EMF methods are used for crosstalk between nonuniform lines. It is shown that the potential method is equivalent to classical coupled transmission line theory for the case of uniform lines. An experiment was performed for uniform coupled microstrip lines for frequencies from 50 MHz to 5 GHz, and good agreement between theory and measurement was obtained for both near- and far-end crosstalk 相似文献
10.
D Galasko T Saitoh Y Xia LJ Thal R Katzman LR Hill L Hansen 《Canadian Metallurgical Quarterly》1994,44(10):1950-1951
We determined apolipoprotein E (ApoE) genotypes in 122 autopsied demented patients. The frequency of the ApoE epsilon 4 allele was 39.6% in Alzheimer's disease (AD), 29.0% in the Lewy body variant of AD (LBV), and 6.25% in diffuse Lewy body disease. For AD and LBV patients, the epsilon 4 frequency was significantly higher than that reported in nondemented controls (10 to 15%). Therefore, LBV and AD share ApoE epsilon 4 as a genetic risk factor, providing further evidence that these conditions overlap. 相似文献