全文获取类型
收费全文 | 3462篇 |
免费 | 184篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 61篇 |
化学工业 | 836篇 |
金属工艺 | 53篇 |
机械仪表 | 35篇 |
建筑科学 | 95篇 |
矿业工程 | 3篇 |
能源动力 | 76篇 |
轻工业 | 407篇 |
水利工程 | 38篇 |
石油天然气 | 19篇 |
无线电 | 341篇 |
一般工业技术 | 557篇 |
冶金工业 | 740篇 |
原子能技术 | 22篇 |
自动化技术 | 367篇 |
出版年
2024年 | 8篇 |
2023年 | 37篇 |
2022年 | 104篇 |
2021年 | 141篇 |
2020年 | 73篇 |
2019年 | 77篇 |
2018年 | 91篇 |
2017年 | 115篇 |
2016年 | 113篇 |
2015年 | 94篇 |
2014年 | 144篇 |
2013年 | 164篇 |
2012年 | 164篇 |
2011年 | 269篇 |
2010年 | 168篇 |
2009年 | 175篇 |
2008年 | 176篇 |
2007年 | 179篇 |
2006年 | 128篇 |
2005年 | 102篇 |
2004年 | 86篇 |
2003年 | 76篇 |
2002年 | 82篇 |
2001年 | 54篇 |
2000年 | 40篇 |
1999年 | 48篇 |
1998年 | 148篇 |
1997年 | 83篇 |
1996年 | 71篇 |
1995年 | 63篇 |
1994年 | 43篇 |
1993年 | 46篇 |
1992年 | 24篇 |
1991年 | 23篇 |
1990年 | 26篇 |
1989年 | 20篇 |
1988年 | 18篇 |
1987年 | 21篇 |
1986年 | 22篇 |
1985年 | 16篇 |
1984年 | 15篇 |
1983年 | 13篇 |
1982年 | 6篇 |
1981年 | 13篇 |
1980年 | 7篇 |
1979年 | 9篇 |
1977年 | 5篇 |
1976年 | 18篇 |
1973年 | 5篇 |
1970年 | 7篇 |
排序方式: 共有3650条查询结果,搜索用时 15 毫秒
41.
R. Gul K. Keeter R. Rodriguez A.E. Bolotnikov A. Hossain G.S. Camarda K.H. Kim G. Yang Y. Cui V. Carcelen J. Franc Z. Li R.B. James 《Journal of Electronic Materials》2012,41(3):488-493
We studied, by current deep-level transient spectroscopy (I-DLTS), point defects induced in CdZnTe detectors by three dopants: Pb, Bi, and In. Pb-doped CdZnTe detectors have a new acceptor trap at around 0.48?eV. The absence of a VCd trap suggests that all Cd vacancies are compensated by Pb interstitials after they form a deep-acceptor complex [[PbCd]+-V Cd 2? ]?. Bi-doped CdZnTe detectors had two distinct traps: a shallow trap at around 36?meV and a deep donor trap at around 0.82?eV. In detectors doped with In, we noted three well-known traps: two acceptor levels at around 0.18?eV (A-centers) and 0.31?eV (VCd), and a deep trap at around 1.1?eV. 相似文献
42.
Zachary T. Rosenkrans Jessica C. Hsu Eduardo Aluicio-Sarduy Todd E. Barnhart Jonathan W. Engle Weibo Cai 《Advanced functional materials》2023,33(33):2302777
The therapeutic efficacy of photodynamic therapy is limited by the ability of light to penetrate tissues. Due to this limitation, Cerenkov luminescence (CL) from radionuclides has recently been proposed as an alternative light source in a strategy referred to as Cerenkov radiation-induced therapy (CRIT). Semiconducting polymer nanoparticles (SPNs) have ideal optical properties, such as large absorption cross-sections and broad absorbance, which can be utilized to harness the relatively weak CL produced by radionuclides. SPNs can be doped with photosensitizers and have ≈100% energy transfer efficiency by multiple energy transfer mechanisms. Herein, an optimized photosensitizer-doped SPN is investigated as a nanosystem to harness and amplify CL for cancer theranostics. It is found that semiconducting polymers significantly amplify CL energy transfer efficiency. Bimodal positron emission tomography (PET) and optical imaging studies show high tumor uptake and retention of the optimized SPNs when administered intravenously or intratumorally. Lastly, it is found that photosensitizer-doped SPNs have excellent potential as a cancer theranostics nanosystem in an in vivo tumor therapy study. This study shows that SPNs are ideally suited to harness and amplify CL for cancer theranostics, which may provide a significant advancement for CRIT that are unabated by tissue penetration limits. 相似文献
43.
Ronald E. Rice Sandra K. Evans Katy E. Pearce Anu Sivunen Jessica Vitak Jeffrey W. Treem 《The Journal of communication》2017,67(1):106-130
The concept of affordances has been increasingly applied to the study of information and communication technologies (ICTs) in organizational contexts. However, almost no research operationalizes affordances, limiting comparisons and programmatic research. This article briefly reviews conceptualizations and possibilities of affordances in general and for media, then introduces the concept of organizational media affordances as organizational resources. Analysis of survey data from a large Nordic media organization identified six reliable and valid organizational media affordances: pervasiveness, editability, self-presentation, searchability, visibility, and awareness. Eight media scales based on frequency of use of 10 media within each of three organization levels were differentially associated with these affordances. The conceptualization, measurement approach, and results from this study provide the foundation for considerable future organizational communication and ICT research. 相似文献
44.
Diner D.J. Beckert J.C. Bothwell G.W. Rodriguez J.I. 《Geoscience and Remote Sensing, IEEE Transactions on》2002,40(7):1449-1466
The Multi-angle Imaging SpectroRadiometer, one of five science instruments aboard NASA's Terra spacecraft, was launched into Earth orbit in December 1999. Acquisition of Earth imagery began in February 2000, and the quality of the data is excellent. Overall, MISR has been performing superbly, though the instrument exhibits several idiosyncrasies, some of which were anticipated prior to launch. Details regarding the in-flight performance of the instrument system are presented. 相似文献
45.
This work presents a computational matrix framework in terms of tensor signal algebra for the formulation of discrete chirp Fourier transform algorithms.These algorithms are used in this work to estimate the point target functions(impulse response functions)of multiple-input multiple-output(MIMO)synthetic aperture radar(SAR)systems.This estimation technique is being studied as an alternative to the estimation of point target functions using the discrete cross-ambiguity function for certain types of environmental surveillance applications.The tensor signal algebra is presented as a mathematics environment composed of signal spaces,finite dimensional linear operators,and special matrices where algebraic methods are used to generate these signal transforms as computational estimators.Also,the tensor signal algebra contributes to analysis,design,and implementation of parallel algorithms.An instantiation of the framework was performed by using the MATLAB Parallel Computing Toolbox,where all the algorithms presented in this paper were implemented. 相似文献
46.
H. Fan A. Wright J. Gabaldon A. Rodriguez C.J. Brinker Y.‐B. Jiang 《Advanced functional materials》2006,16(7)
The synthesis of three‐dimensionally ordered, transparent gold‐nanocrystal (NC)/silica superlattice thin films using the self‐assembly (by spin‐coating) of water‐soluble gold nanocrystal micelles and soluble silica is reported by Fan and co‐workers on p. 891. The robust, 3D NC/silica superlattice films are of interest for the development of collective optical and electronic phenomena, and, importantly, for the integration of NC arrays into device architectures. Nanocrystals and their ordered arrays hold many important applications in fields such as catalysis, surface‐enhanced Raman spectroscopy based sensors, memory storage, and electronic and optical nanodevices. Herein, a simple and general method to synthesize ordered, three‐dimensional, transparent gold nanocrystal/silica superlattice thin films by self‐assembly of gold nanocrystal micelles with silica or organosilsesquioxane by spin‐coating is reported. The self‐assembly process is conducted under acidic sol–gel conditions (ca. pH 2), ensuring spin‐solution homogeneity and stability and facilitating the formation of ordered and transparent gold nanocrystal/silica films. The monodisperse nanocrystals are organized within inorganic host matrices as a face‐centered cubic mesostructure, and characterized by transmission electron spectroscopy and X‐ray diffraction. 相似文献
47.
A methodology for designing,modifying, and implementing Fourier transform algorithms on various architectures 总被引:1,自引:0,他引:1
J. R. Johnson R. W. Johnson D. Rodriguez R. Tolimieri 《Circuits, Systems, and Signal Processing》1990,9(4):449-500
Fourier transform algorithms are described using tensor (Kronecker) products and an associated class of permutations. Algebraic properties of tensor products and the related permutations are used to derive variants of the Cooley-Tukey fast Fourier transform algorithm. These algorithms can be implemented by translating tensor products and permutations to programming constructs. An implementation can be matched to a specific computer architecture by selecting the appropriate variant. This methodology is carried out for the Cray X-MP and the AT&T DSP32.This work was performed at the Center for Large Scale Computation, Suite 400, 25 West 43rd Street, New York, New York 10036, USA, and was supported by a grant from DARPA/ACMP. 相似文献
48.
Roland Mainz Alfons Weber Humberto Rodriguez‐Alvarez Sergiu Levcenko Manuela Klaus Paul Pistor Reiner Klenk Hans‐Werner Schock 《Progress in Photovoltaics: Research and Applications》2015,23(9):1131-1143
Ga segregation at the backside of Cu(In,Ga)Se2 solar cell absorbers is a commonly observed phenomenon for a large variety of sequential fabrication processes. Here, we investigate the correlation between Se incorporation, phase formation and Ga segregation during fast selenisation of Cu–In–Ga precursor films in elemental selenium vapour. Se incorporation and phase formation are analysed by real‐time synchrotron‐based X‐ray diffraction and fluorescence analysis. Correlations between phase formation and depth distributions are gained by interrupting the process at several points and by subsequent ex situ cross‐sectional electron microscopy and Raman spectroscopy. The presented results reveal that the main share of Se incorporation takes place within a few seconds during formation of In–Se at the top part of the film, accompanied by outdiffusion of In out of a ternary Cu–In–Ga phase. Surprisingly, CuInSe2 starts to form at the surface on top of the In–Se layer, leading to an intermediate double graded Cu depth distribution. The remaining Ga‐rich metal phase at the back is finally selenised by indiffusion of Se. On the basis of a proposed growth model, we discuss possible strategies and limitations for the avoidance of Ga segregation during fast selenisation of metallic precursors. Solar cells made from samples selenised with a total annealing time of 6.5 min reached conversion efficiencies of up to 14.2 % (total area, without anti‐reflective coating). The evolution of the Cu(In,Ga)Se2 diffraction signals reveals that the minimum process time for high‐quality Cu(In,Ga)Se2 absorbers is limited by cation ordering rather than Se incorporation. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
49.
Quartz Films: Water‐Induced Phase Separation Forming Macrostructured Epitaxial Quartz Films on Silicon (Adv. Funct. Mater. 35/2014) 下载免费PDF全文
50.
Raul D. Rodriguez Sergey Shchadenko Gennadiy Murastov Anna Lipovka Maxim Fatkullin Ilia Petrov Tuan-Hoang Tran Alimzhan Khalelov Muhammad Saqib Nelson E. Villa Vladimir Bogoslovskiy Yan Wang Chang-Gang Hu Alexey Zinovyev Wenbo Sheng Jin-Ju Chen Ihsan Amin Evgeniya Sheremet 《Advanced functional materials》2021,31(17):2008818
Polyethylene terephthalate (PET) is the most widely used polymer in the world. For the first time, the laser-driven integration of aluminum nanoparticles (Al NPs) into PET to realize a laser-induced graphene/Al NPs/polymer composite, which demonstrates excellent toughness and high electrical conductivity with the formation of aluminum carbide into the polymer is shown. The conductive structures show an impressive mechanical resistance against >10000 bending cycles, projectile impact, hammering, abrasion, and structural and chemical stability when in contact with different solvents (ethanol, water, and aqueous electrolytes). Devices including thermal heaters, carbon electrodes for energy storage, electrochemical and bending sensors show this technology's practical application for ultra-robust polymer electronics. This laser-based technology can be extended to integrating other nanomaterials and create hybrid graphene-based structures with excellent properties in a wide range of flexible electronics’ applications. 相似文献