全文获取类型
收费全文 | 1752篇 |
免费 | 70篇 |
专业分类
电工技术 | 16篇 |
综合类 | 3篇 |
化学工业 | 574篇 |
金属工艺 | 27篇 |
机械仪表 | 27篇 |
建筑科学 | 141篇 |
矿业工程 | 5篇 |
能源动力 | 42篇 |
轻工业 | 203篇 |
水利工程 | 7篇 |
石油天然气 | 1篇 |
无线电 | 96篇 |
一般工业技术 | 343篇 |
冶金工业 | 212篇 |
原子能技术 | 15篇 |
自动化技术 | 110篇 |
出版年
2021年 | 26篇 |
2020年 | 17篇 |
2019年 | 24篇 |
2018年 | 32篇 |
2017年 | 30篇 |
2016年 | 39篇 |
2015年 | 41篇 |
2014年 | 43篇 |
2013年 | 72篇 |
2012年 | 65篇 |
2011年 | 80篇 |
2010年 | 46篇 |
2009年 | 66篇 |
2008年 | 70篇 |
2007年 | 60篇 |
2006年 | 51篇 |
2005年 | 49篇 |
2004年 | 56篇 |
2003年 | 34篇 |
2002年 | 37篇 |
2001年 | 30篇 |
2000年 | 28篇 |
1999年 | 18篇 |
1998年 | 28篇 |
1997年 | 31篇 |
1996年 | 37篇 |
1995年 | 26篇 |
1994年 | 21篇 |
1993年 | 33篇 |
1992年 | 19篇 |
1991年 | 28篇 |
1990年 | 21篇 |
1989年 | 27篇 |
1988年 | 16篇 |
1985年 | 31篇 |
1984年 | 34篇 |
1983年 | 28篇 |
1982年 | 27篇 |
1981年 | 30篇 |
1980年 | 28篇 |
1979年 | 22篇 |
1978年 | 27篇 |
1976年 | 19篇 |
1975年 | 18篇 |
1974年 | 28篇 |
1973年 | 20篇 |
1972年 | 17篇 |
1971年 | 15篇 |
1970年 | 16篇 |
1969年 | 17篇 |
排序方式: 共有1822条查询结果,搜索用时 15 毫秒
41.
Jiale Feng Lupeng Yang Alexander S. Romanov Jirawit Ratanapreechachai Antti‐Pekka M. Reponen Saul T. E. Jones Mikko Linnolahti Timothy J. H. Hele Anna Khler Heinz Bssler Manfred Bochmann Dan Credgington 《Advanced functional materials》2020,30(9)
Carbene‐metal‐amides (CMAs) are a promising family of donor–bridge–acceptor molecular charge‐transfer (CT) emitters for organic light‐emitting diodes. A universal approach is demonstrated to tune the energy of their CT emission. A blueshift of up to 210 meV is achievable in solid state via dilution in a polar host matrix. The origin of this shift has two components: constraint of thermally‐activated triplet diffusion, and electrostatic interactions between guest and polar host. This allows the emission of mid‐green CMA archetypes to be tuned to sky blue without chemical modifications. Monte‐Carlo simulations based on a Marcus‐type transfer integral successfully reproduce the concentration‐ and temperature‐dependent triplet diffusion process, revealing a substantial shift in the ensemble density of states in polar hosts. In gold‐bridged CMAs, this shift does not lead to a significant change in luminescence lifetime, thermal activation energy, reorganization energy, or intersystem crossing rate. These discoveries offer new insight into coupling between the singlet and triplet manifolds in CMA materials, revealing a dominant interaction between states of CT character. The same approach is employed using materials which have been chemically modified to alter the energy of their CT state directly, shifting the emission of sky‐blue chromophores into the practical blue range. 相似文献
42.
43.
Leopold Weber Wolfgang Lenhardt Franz Möstl Gregor Götzl Julia Weilbold Heinz Reitner 《BHM Berg- und Hüttenm?nnische Monatshefte》2016,161(4):148-155
Touristic mines are by far not only of public interest. During guided tours the importance of mining and mineral resources for society can be explained in a proper way. Mineral deposits, for long time not accessible and only known from old literature can now be studied in detail by scientists. Old underground mines can be used for different purposes. With respect to Arzberg the different possibilities of utilization of old underground workings are described in detail: A touristic mine serves not only as an attraction, but also as a training centre for underground geological mapping, geochemistry and geophysics research laboratory of universities. For many years the ZAMG (Central Institute for Meteorology and Geodynamics) has been operating a seismic station, and parts of the old mine workings have been used for cheese refinery since 2006. Furthermore, the mine water is utilized for extracting geothermal energy and serves the cooling chambers. The combined use of the old mine workings by different parties permits sharing the substantial maintenance costs. 相似文献
44.
Riener Heinz Haedicke Finn Frehse Stefan Soeken Mathias Große Daniel Drechsler Rolf Fey Goerschwin 《International Journal on Software Tools for Technology Transfer (STTT)》2017,19(5):605-621
International Journal on Software Tools for Technology Transfer - Many applications from artificial intelligence and formal methods use decision procedures as their core solving engines. In this... 相似文献
45.
Gerhard Heise Andreas Brner Marcel Dickmann Marina Englmaier Andreas Heiss Matthias Kemnitzer Jan Konrad Regina Moser Jrg Palm Helmut Vogt Heinz P. Huber 《Progress in Photovoltaics: Research and Applications》2015,23(10):1291-1304
In this paper, we present the selective structuring of all three patterns (P1, P2 and P3) of a monolithic interconnection of CIS (Cu(In,Ga)(S,Se)2) thin film solar cells by picosecond laser pulses at a wavelength of 1064 nm. We show results for single pulse ablation threshold values and line scribing of molybdenum films on glass (P1), CIS on molybdenum (P2) and zinc oxide on CIS (P3). The purposes of these processes are the p‐type isolation (P1), cell interconnect (P2) and n‐type isolation (P3), which are required for complete cell architecture. The half micron thick molybdenum back electrode can be structured with a process speed of more than 15 m/s at about 15 W average power without detectable residues and damage by direct induced laser ablation from the back side (P1). The CIS layer can be structured selectively down to the molybdenum at process speeds up to 1 m/s at about 15 W average power, due to the precision of direct laser ablation in the ultrashort pulse regime (P2). The ZnO front electrode layer is separated by clean trenches with straight side walls at process speeds of up to 15 m/s at about 10 W average power, as a result of indirect induced laser ablation (P3). A validation of functionality of all processes is demonstrated on CIS solar cell modules (30 × 30 cm2). By replacing one state‐of‐the‐art process by a picosecond laser process at a time, solar efficiencies could be increased for P1 and P2 and stayed on a similar level for P3. After an optimization of the patterning processes in the R&D pilot line of AVANCIS, we achieved a new record efficiency for an all‐laser‐patterned CIS solar module: 14.7% as best value for the aperture area efficiency of a 30 × 30 cm2 sized CIS module was reached. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
46.
About the Reactions of Benzimidazole-2-carbohydrazide with Electrophilic Compounds Benzimidazole-2-carbohydrazide ( 1 ) reacts with aldehydes and ketones to form N-alkylidene-benzimidazole-2-carbohydrazides( 2a–j ). With carbon disulfide, diphenyl carbonate and cyanates, ring closure takes place to afford 1,2,4-triazines and 1,3,4-oxadiazoles. Attempts to synthezise 2-isocyanato-benzimidazole failed. 1H-n.m.r. and 13C-n.m.r. spectroscopic data of the compounds are given. 相似文献
47.
Ilse Bacaloglu Truong The Ky Carmen Boeriu Hans Horst Glatt Radu Bacaloglu Dieter Martin Heinz Graubaum 《Advanced Synthesis \u0026amp; Catalysis》1982,324(5):803-808
Acylation of Heterocycles with Carbonic Acid Derivatives. I. Kinetics and Mechanism of the Reaction of 2-Aminobenzimidazoles with Aryl Cyanates The second order rate constants for the reaction of 2-amino-benzimidazoles (2-ABI) with aryl cyanates forming 2-amino-benzimidazole aryl ester imide 3 have been determined in dependence on substituent effects by u. v. measurements. The results are interpreted by a six-membered cyclic transition state in which the electrophilic attack of the cyanate on the endocyclic N atom is catalyzed by an H bridge interaction of the exocyclic amino group of 2-ABI with the OCN group. 相似文献
48.
Heinz Graubaum 《Advanced Synthesis \u0026amp; Catalysis》1993,335(7):585-588
Acyl Migrations on 3(5)-Amino-pyrazole 3(5)-Amino-pyrazole 1 form 3 isomeric monoacylation products, 4 diacylation products and 3 triacylation products by reaction with electrophiles like cyanates, isocyanates or carboxylic and chlorides, respectively. Acyl migrations are observed depending on the reaction temperature and the structure of the acyl residue. The structures of the acyl derivatives of 3(5)-amino-pyrazole were characterized by nmr-spectroscopy. 相似文献
49.
Marie-Aime Plancquaert Zdenek Janousek Heinz G. Viehe 《Advanced Synthesis \u0026amp; Catalysis》1994,336(1):19-28
An improved synthesis of CTMC is described. This cyclobutene is thermally stable towards electrocyclic ring opening. Its reactivity is explored and a number of radical adducts are described. A more complicated picture is observed with various nucleophiles. The strong dienophilic character of CTMC is illustrated by numerous examples. CTMC reacts well as a dipolarophile with diphenylnitrone, diphenylnitrilimine and diazoalkanes. The high reactivity of this cyclobutene is due to its inherent polarity and strain. 相似文献
50.
Products of the reaction of propane-2-sulphonic acid p-cresylester with sodium butoxide in butanol are the sodium salt of propan-2-sulphonic acid, di-n-butyl ether, p-cresyl-n-butyl ether and p-cresol. The reaction proceeds via propane-2-sulphonic acid n-butylester which is formed from the starting compound by an elimination-addition (sulphene) mechanism. The elimination step is an E1-cB reaction. 相似文献