全文获取类型
收费全文 | 512571篇 |
免费 | 4748篇 |
国内免费 | 1126篇 |
专业分类
电工技术 | 9139篇 |
综合类 | 353篇 |
化学工业 | 76327篇 |
金属工艺 | 27288篇 |
机械仪表 | 18609篇 |
建筑科学 | 10662篇 |
矿业工程 | 4651篇 |
能源动力 | 10869篇 |
轻工业 | 30254篇 |
水利工程 | 6518篇 |
石油天然气 | 15266篇 |
武器工业 | 40篇 |
无线电 | 54953篇 |
一般工业技术 | 115537篇 |
冶金工业 | 80077篇 |
原子能技术 | 15049篇 |
自动化技术 | 42853篇 |
出版年
2021年 | 4518篇 |
2019年 | 4278篇 |
2018年 | 12817篇 |
2017年 | 13242篇 |
2016年 | 11698篇 |
2015年 | 5172篇 |
2014年 | 8641篇 |
2013年 | 20117篇 |
2012年 | 14098篇 |
2011年 | 21105篇 |
2010年 | 17914篇 |
2009年 | 18585篇 |
2008年 | 19330篇 |
2007年 | 20272篇 |
2006年 | 12877篇 |
2005年 | 13170篇 |
2004年 | 12216篇 |
2003年 | 12207篇 |
2002年 | 10966篇 |
2001年 | 10838篇 |
2000年 | 10351篇 |
1999年 | 10096篇 |
1998年 | 22908篇 |
1997年 | 16580篇 |
1996年 | 12728篇 |
1995年 | 9807篇 |
1994年 | 8924篇 |
1993年 | 9016篇 |
1992年 | 6946篇 |
1991年 | 6900篇 |
1990年 | 6856篇 |
1989年 | 6536篇 |
1988年 | 6363篇 |
1987年 | 5843篇 |
1986年 | 5703篇 |
1985年 | 6104篇 |
1984年 | 5761篇 |
1983年 | 5540篇 |
1982年 | 5215篇 |
1981年 | 5197篇 |
1980年 | 5141篇 |
1979年 | 5119篇 |
1978年 | 5137篇 |
1977年 | 5639篇 |
1976年 | 7029篇 |
1975年 | 4592篇 |
1974年 | 4638篇 |
1973年 | 4641篇 |
1972年 | 4081篇 |
1971年 | 3628篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
Kuznetsov Yu. A. Markov M. A. Kravchenko I. N. Krasikov A. V. Bykova A. D. 《Refractories and Industrial Ceramics》2021,62(4):421-425
Refractories and Industrial Ceramics - The paper introduces a promising technology for utilizing a traditional scheme for implementing a flow-through micro-arc oxidation method to restore localized... 相似文献
2.
F.T. Munna Vidhya Selvanathan K. Sobayel Ghulam Muhammad Nilofar Asim Nowshad Amin Kamaruzzaman Sopian Md. Akhtaruzzaman 《Ceramics International》2021,47(8):11003-11009
In this study, dilute chemical bath deposition technique has been used to deposit CdZnS thin films on soda-lime glass substrates. The structural, morphological, optoelectronic properties of as-grown films have been investigated as a function of different Zn2+ precursor concentrations. The X-ray diffractogram of CdS thin-film reveals a peak corresponding to (002) plane with wurtzite structure, and the peak shift has been observed with the increase of the Zn2+ concentration upon formation of CdZnS thin film. From morphological studies, it has been revealed that the diluted chemical bath deposition technique provides homogeneous distribution of film on the substrate even at a lower concentration of Zn2+. Optical characterization has shown that the transparency of the film is influenced by Zn2+ concentration and when the Zn2+ concentration is varied from 0 M to 0.0256 M, bandgap values of resulting films range from 2.42 eV to 3.90 eV while. Furthermore, electrical properties have shown that with increasing zinc concentration the resistivity of the film increases. Finally, numerical simulation validates and suggests that CdZnS buffer layer with composition of 0.0032 M Zn2+ concentration would be a promising candidate in CIGS solar cell. 相似文献
3.
Glass and Ceramics - Ceramic bricks based on low-melting clay and ferro-dust from self-disintegrating, low-carbon, ferrochrome slags, graded from M100 to M175, respectively, were obtained in the... 相似文献
4.
Golam Haider Krishna Sampathkumar Tim Verhagen Lukáš Nádvorník Farjana J. Sonia Václav Valeš Jan Sýkora Peter Kapusta Petr Němec Martin Hof Otakar Frank Yang-Fang Chen Jana Vejpravová Martin Kalbáč 《Advanced functional materials》2021,31(29):2102196
Recent advancements in isolation and stacking of layered van der Waals materials have created an unprecedented paradigm for demonstrating varieties of 2D quantum materials. Rationally designed van der Waals heterostructures composed of monolayer transition-metal dichalcogenides (TMDs) and few-layer hBN show several unique optoelectronic features driven by correlations. However, entangled superradiant excitonic species in such systems have not been observed before. In this report, it is demonstrated that strong suppression of phonon population at low temperature results in a formation of a coherent excitonic-dipoles ensemble in the heterostructure, and the collective oscillation of those dipoles stimulates a robust phase synchronized ultra-narrow band superradiant emission even at extremely low pumping intensity. Such emitters are in high demand for a multitude of applications, including fundamental research on many-body correlations and other state-of-the-art technologies. This timely demonstration paves the way for further exploration of ultralow-threshold quantum-emitting devices with unmatched design freedom and spectral tunability. 相似文献
5.
Automation and Remote Control - A linear-quadratic positional differential game of three persons is considered. Coefficient criteria are established under which there is no Nash equilibrium... 相似文献
6.
S. Sarika S. Abhilash V.S. Sumi S. Rijith 《International Journal of Hydrogen Energy》2021,46(30):16387-16403
A promising electrocatalyst containing variable percentage of V2O5–TiO2 mixed oxide in graphene oxide support was prepared by embedding the catalyst on Cu substrate through facile electroless Ni–Co–P plating for hydrogen evolution reaction. The solvothermal decomposition method was opted for tuning the crystalline characteristics of prepared material. The optimized mixed oxide was well characterized, active sites centres were identified and explained by X-ray diffraction, high resolution tunnelling electron microscopy, scanning electron microscopy coupled with energy dispersive X-ray and X-ray photon spectroscopy analysis. The structural and electronic characteristics of material was done by fourier transform infrared spectroscopy and the electrochemical behaviour of the prepared material was evaluated by using Tafel plot, electrochemical impedance analysis, linear sweep voltammetry, open circuit analysis and chronoamperometry measurements. The results show the enhanced catalytic activity of Ni–Co–P than pure Ni–P plate, due to synergic effect. Moreover, the prepared mixed oxide incorporated Ni–Co–P plate has a high activity towards HER with low over potential of 101 mV, low Tafel slope of 36 mVdec?1, high exchange current density of 9.90 × 10?2 Acm?2. 相似文献
7.
A. Nakano T. Shimazaki M. Sekiya H. Shiozawa K. Ohtsuka A. Aoyagi T. Iwakiri Z. Mikami M. Sato Y. Sugino K. Kinoshita T. Matsuoka T. Imamura Y. Takayama K. Yamamoto 《International Journal of Hydrogen Energy》2021,46(29):15649-15659
Monitoring the temperature in liquid hydrogen (LH2) storage tanks on ships is important for the safety of maritime navigation. In addition, accurate temperature measurement is also required for commercial transactions. Temperature and pressure define the density of liquid hydrogen, which is directly linked to trading interests. In this study, we developed and tested a liquid hydrogen temperature monitoring system that uses platinum resistance sensors with a nominal electrical resistance of approximately 1000 Ω at room temperature, PT-1000, for marine applications. The temperature measurements were carried out using a newly developed temperature monitoring system under different pressure conditions. The measured values are compared with a calibrated reference PT-1000 resistance thermometer. We confirm a measurement accuracy of ±50 mK in a pressure range of 0.1 MPa–0.5 MPa. 相似文献
8.
Blagoveshchenskii D. I. Kozlovskii V. N. Vasin S. A. 《Russian Engineering Research》2021,41(12):1255-1259
Russian Engineering Research - Digital tools for managing improvements in automobile production are developed. An operative tool provides warnings regarding the operational quality of the vehicles... 相似文献
9.
Automation and Remote Control - We consider multicriteria minimax optimization problems with criteria in the form of the maxima of functionals given by the induced norms of linear operators taking... 相似文献
10.
Viktoria M. S. Kjær Loukas Ieremias Dr. Viktorija Daugvilaite Dr. Michael Lückmann Prof. Thomas M. Frimurer Prof. Trond Ulven Prof. Mette M. Rosenkilde Dr. Jon Våbenø 《ChemMedChem》2021,16(17):2623-2627
The G protein-coupled receptor GPR183/EBI2, which is activated by oxysterols, is a therapeutic target for inflammatory and metabolic diseases where both antagonists and agonists are of potential interest. Using the piperazine diamide core of the known GPR183 antagonist (E)-3-(4-bromophenyl)-1-(4-(4-methoxybenzoyl)piperazin-1-yl)prop-2-en-1-one (NIBR189) as starting point, we identified and sourced 79 structurally related compounds that were commercially available. In vitro screening of this compound collection using a Ca2+ mobilization assay resulted in the identification of 10 compounds with agonist properties. To enable establishment of initial structure-activity relationship trends, these were supplemented with five in-house compounds, two of which were also shown to be GPR183 agonists. Taken together, our findings suggest that the agonist activity of this compound series is dictated by the substitution pattern of one of the two distal phenyl rings, which functions as a molecular efficacy-switch. 相似文献