全文获取类型
收费全文 | 4444篇 |
免费 | 240篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 55篇 |
综合类 | 4篇 |
化学工业 | 1162篇 |
金属工艺 | 64篇 |
机械仪表 | 79篇 |
建筑科学 | 159篇 |
矿业工程 | 18篇 |
能源动力 | 177篇 |
轻工业 | 791篇 |
水利工程 | 24篇 |
石油天然气 | 16篇 |
无线电 | 212篇 |
一般工业技术 | 717篇 |
冶金工业 | 200篇 |
原子能技术 | 21篇 |
自动化技术 | 987篇 |
出版年
2024年 | 14篇 |
2023年 | 49篇 |
2022年 | 201篇 |
2021年 | 199篇 |
2020年 | 124篇 |
2019年 | 147篇 |
2018年 | 186篇 |
2017年 | 176篇 |
2016年 | 179篇 |
2015年 | 154篇 |
2014年 | 193篇 |
2013年 | 339篇 |
2012年 | 329篇 |
2011年 | 361篇 |
2010年 | 283篇 |
2009年 | 240篇 |
2008年 | 253篇 |
2007年 | 211篇 |
2006年 | 163篇 |
2005年 | 147篇 |
2004年 | 105篇 |
2003年 | 95篇 |
2002年 | 93篇 |
2001年 | 44篇 |
2000年 | 39篇 |
1999年 | 34篇 |
1998年 | 44篇 |
1997年 | 32篇 |
1996年 | 25篇 |
1995年 | 43篇 |
1994年 | 18篇 |
1993年 | 17篇 |
1992年 | 12篇 |
1991年 | 17篇 |
1990年 | 13篇 |
1989年 | 13篇 |
1988年 | 9篇 |
1987年 | 6篇 |
1986年 | 5篇 |
1985年 | 7篇 |
1984年 | 11篇 |
1983年 | 8篇 |
1981年 | 3篇 |
1980年 | 3篇 |
1979年 | 7篇 |
1978年 | 4篇 |
1977年 | 5篇 |
1976年 | 4篇 |
1975年 | 8篇 |
1974年 | 3篇 |
排序方式: 共有4686条查询结果,搜索用时 15 毫秒
41.
Jian-Qing Lu Rabah Boukherroub Georges Manuel William P. Weber 《Journal of Inorganic and Organometallic Polymers》1995,5(1):61-74
Poly[1-methyl-1-[3-(3-pyridinyl)propyl]-1-sila-cis-pent-3-ene], poly[1-phenyl-1-[3-(3-pyridinyl)propyl)-1-sila-cis-pent-3-ene], and poly[1-phenyl-1-(4-pyridinyl)-1-sila-cis-pent-3-ene] were synthesized by the anionic ring-opening polymerization of 1-methyl-1-[3-(3-pyridinyl)propyl]-1-silacyclopent-3-ene, 1-phenyl-1-[3-(3-pyridinyl)propyl]-1-silacyclopent-3-ene, and 1-phenyl-1-(4-pyridinyl)-1-silacyclopent-3-ene, respectively. These are the first polycarbosilanes which contain heterocyclic pyridine units as side-chain substituents. These polymers were characterized by1H,13C, and29Si NMR as well as by IR and UV spectroscopy. The molecular weight distributions were determined by gel permeation chromatography, glass transition temperatures, by differential seanning calorimetry: (DSC) and thermal behavior, by thermogravimetric analysis. (TGA). 相似文献
42.
Baoyu Li Weifeng Li Jose Manuel Perez‐Aguilar Ruhong Zhou 《Small (Weinheim an der Bergstrasse, Germany)》2017,13(12)
The development of biocompatible nanomaterials for smart drug delivery and bioimaging has attracted great interest in recent years in biomedical fields. Here, the interaction between the recently reported nitrogenated graphene (C2N) and a prototypical protein (villin headpiece HP35) utilizing atomistic molecular dynamics simulations is studied. The simulations reveal that HP35 can form a stable binding with the C2N monolayer. Although the C2N–HP35 attractive interactions are constantly preserved, the binding strength between C2N and the protein is mild and does not cause significant distortion in the protein's structural integrity. This intrinsic biofriendly property of native C2N is distinct from several widely studied nanomaterials, such as graphene, carbon nanotubes, and MoS2, which can induce severe protein denaturation. Interestingly, once the protein is adsorbed onto C2N surface, its transverse migration is highly restricted at the binding sites. This restriction is orchestrated by C2N's periodic porous structure with negatively charged “holes,” where the basic residues—such as lysine—can form stable interactions, thus functioning as “anchor points” in confining the protein displacement. It is suggested that the mild, immobilized protein attraction and biofriendly aspects of C2N would make it a prospective candidate in bio‐ and medical‐related applications. 相似文献
43.
44.
45.
Qi Jia Xin Ou Manuel Langer Benjamin Schreiber Jörg Grenzer Pablo F. Siles Raul D. Rodriguez Kai Huang Ye Yuan Alireza Heidarian René Hübner Tiangui You Wenjie Yu Kilian Lenz Jürgen Lindner Xi Wang Stefan Facsko 《Nano Research》2018,11(7):3519-3528
A nanofabrication method for the production of ultra-dense planar metallic nanowire arrays scalable to wafer-size is presented. The method is based on an efficient template deposition process to grow diverse metallic nanowire arrays with extreme regularity in only two steps. First, III–V semiconductor substrates are irradiated by a low-energy ion beam at an elevated temperature, forming a highly ordered nanogroove pattern by a “reverse epitaxy” process due to self-assembly of surface vacancies. Second, diverse metallic nanowire arrays (Au, Fe, Ni, Co, FeAl alloy) are fabricated on these III–V templates by deposition at a glancing incidence angle. This method allows for the fabrication of metallic nanowire arrays with periodicities down to 45 nm scaled up to wafer-size fabrication. As typical noble and magnetic metals, the Au and Fe nanowire arrays produced here exhibited large anisotropic optical and magnetic properties, respectively. The excitation of localized surface plasmon resonances (LSPRs) of the Au nanowire arrays resulted in a high electric field enhancement, which was used to detect phthalocyanine (CoPc) in surface-enhanced Raman scattering (SERS). Furthermore, the Fe nanowire arrays showed a very high in-plane magnetic anisotropy of approximately 412 mT, which may be the largest in-plane magnetic anisotropy field yet reported that is solely induced via shape anisotropy within the plane of a thin film. 相似文献
46.
This paper presents the latest developments of the MadeIn 'Coop method for modelling the human-machine and human-human co-operation process, and an application of this method for the design of a more co-operative version of the C3I System CHEOPS. We first consider that the design of software systems for organizations is tied more and more to the perspective of compound Knowledge Production Systems that link humans and machines engaged in a co-operative problem solving process. After exposing the four principles upon which MadeIn 'Coop rests for modelling co-operation, we present an artificial problem solving dialogue between CHEOPS and its users. Consistent with the Group Cognitive Processes Theory framework, we propose a dialogue analysis according to two complimentary points of view: the Collective Problem Solving model, and the Coordination model. This analysis should help system designers to identify new system functionalities to assist problem solving.(C3I) Command Control Communication Intelligence Systems 相似文献
47.
Surrogate modeling approximation using a mixture of experts based on EM joint estimation 总被引:1,自引:1,他引:0
Dimitri Bettebghor Nathalie Bartoli Stéphane Grihon Joseph Morlier Manuel Samuelides 《Structural and Multidisciplinary Optimization》2011,43(2):243-259
An automatic method to combine several local surrogate models is presented. This method is intended to build accurate and
smooth approximation of discontinuous functions that are to be used in structural optimization problems. It strongly relies
on the Expectation−Maximization (EM) algorithm for Gaussian mixture models (GMM). To the end of regression, the inputs are
clustered together with their output values by means of parameter estimation of the joint distribution. A local expert is
then built (linear, quadratic, artificial neural network, moving least squares) on each cluster. Lastly, the local experts
are combined using the Gaussian mixture model parameters found by the EM algorithm to obtain a global model. This method is
tested over both mathematical test cases and an engineering optimization problem from aeronautics and is found to improve
the accuracy of the approximation. 相似文献
48.
This paper proposes a multi-section vector quantization approach for on-line signature recognition. We have used a database
of 330 users which includes 25 skilled forgeries performed by 5 different impostors. This database is larger than those typically
used in the literature. Nevertheless, we also provide results from the SVC database. Our proposed system obtains similar results
as the state-of-the-art online signature recognition algorithm, Dynamic Time Warping, with a reduced computational requirement,
around 47 times lower. In addition, our system improves the database storage requirements due to vector compression, and is
more privacy-friendly because it is not possible to recover the original signature using the codebooks. Experimental results
reveal that our proposed multi-section vector quantization achieves a 98% identification rate, minimum Detection Cost Function
value equal to 2.29% for random forgeries and 7.75% for skilled forgeries. 相似文献
49.
50.