全文获取类型
收费全文 | 210篇 |
免费 | 17篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 1篇 |
化学工业 | 55篇 |
机械仪表 | 1篇 |
建筑科学 | 2篇 |
能源动力 | 9篇 |
轻工业 | 13篇 |
石油天然气 | 2篇 |
无线电 | 30篇 |
一般工业技术 | 44篇 |
冶金工业 | 6篇 |
原子能技术 | 10篇 |
自动化技术 | 56篇 |
出版年
2023年 | 4篇 |
2022年 | 15篇 |
2021年 | 9篇 |
2020年 | 5篇 |
2019年 | 5篇 |
2018年 | 5篇 |
2017年 | 13篇 |
2016年 | 12篇 |
2015年 | 11篇 |
2014年 | 3篇 |
2013年 | 10篇 |
2012年 | 9篇 |
2011年 | 25篇 |
2010年 | 15篇 |
2009年 | 14篇 |
2008年 | 15篇 |
2007年 | 9篇 |
2006年 | 5篇 |
2005年 | 6篇 |
2004年 | 1篇 |
2003年 | 4篇 |
2002年 | 3篇 |
2001年 | 2篇 |
2000年 | 2篇 |
1998年 | 3篇 |
1997年 | 3篇 |
1996年 | 1篇 |
1994年 | 1篇 |
1992年 | 3篇 |
1991年 | 2篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1983年 | 2篇 |
1981年 | 3篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1970年 | 1篇 |
排序方式: 共有229条查询结果,搜索用时 15 毫秒
81.
82.
Summary A geometric programming method, recently developed for the constrained maximization of posynomials, is presented and illustrated by an application to the optimal design of a torsion bar spring.Research supported by the National Science Foundation, Project GP 13546. 相似文献
83.
Iterated Even–Mansour (EM) encryption schemes (also named “key-alternating ciphers”) were extensively studied in recent years as an abstraction of commonly used block ciphers. A large amount of previous works on iterated EM concentrated on security in an information-theoretic model. A central question studied in these papers is: What is the minimal number of rounds for which the resulting cipher is indistinguishable from an ideal cipher? In this paper, we study a similar question in the computational model: What is the minimal number of rounds, assuring that no attack can recover the secret key faster than trivial attacks (such as exhaustive search)? We study this question for the two natural key scheduling variants that were considered in most previous papers: the identical subkeys variant and the independent subkeys variant. In the identical subkeys variant, we improve the best known attack by an additional round and show that \(r=3\) rounds are insufficient for assuring security, by devising a key recovery attack whose running time is about \(n/\log (n)\) times faster than exhaustive search for an \(n\)-bit key. In the independent subkeys variant, we also extend the known results by one round and show that for \(r=2\), there exists a key recovery attack whose running time is faster than the benchmark meet-in-the-middle attack. Despite their generic nature, we show that the attacks can be applied to improve the best known attacks on several concrete ciphers, including the full \({\hbox {AES}^{2}}\) (proposed at Eurocrypt 2012) and reduced-round LED-128 (proposed at CHES 2012). 相似文献
84.
Electrochemical Properties of La0.5Sr0.5Co0.8M0.2O3–δ (M=Mn,Fe, Ni,Cu) Perovskite Cathodes for IT‐SOFCs 下载免费PDF全文
Yen‐Pei Fu Adi Subardi Min‐Yen Hsieh Wen‐Ku Chang 《Journal of the American Ceramic Society》2016,99(4):1345-1352
The electrochemical properties of La0.5Sr0.5Co0.8M0.2O3–δ (M=Mn, Fe, Ni, Cu) cathodes are investigated with chemical bulk diffusion coefficients (Dchem) and polarization resistances. The electrochemical performance of long‐term testing for La0.5Sr0.5Co0.8Cu0.2O3–δ cathode was carried out to investigate its electrochemical stability. In this work, an anode‐supported single cell with a thick‐film SDC electrolyte (30 μm), a Ni‐SDC cermet anode (1 mm), and a La0.5Sr0.5Co0.8Cu0.2O3–δ cathode (10 μm) reaches a maximum peak power density of 983 mW/cm2 at 700°C. Obviously, Cu substitution for B‐site of La0.5Sr0.5CoO3–δ cathode reduced thermal expansion coefficient (TEC) value and enhanced oxygen bulk diffusion and electrochemical properties. La0.5Sr0.5Co0.8Cu0.2O3–δ is a promising cathode material for intermediate temperature solid oxide fuel cells (IT‐SOFC). 相似文献
85.
Pyrene removal by polycation-montmorillonite (MMT) composites and granulated activated carbon (GAC) in the presence of humic acid (HA) was examined. Pyrene, HA, and sorbent interactions were characterized by FTIR, fluorescence and zeta measurements, adsorption, and column filtration experiments. Pyrene binding coefficients to the macromolecules were in the order of PVPcoS (poly-4-vinylpiridine-co-styrene) > HA > PDADMAC (poly diallyl-dimethyl-ammonium-chloride), correlating to pyrene-macromolecules compatibility. Electrostatic interactions explained the high adsorption of HA to both composites (~100%), whereas HA adsorption by GAC was low. Pyrene removal by the composites, unlike GAC, was enhanced in the presence of HA; removal by PDADMAC-MMT increased from ~50 (k(d) = 2.2 × 10(3) kg/L) to ~70% (k(d) = 2.4 × 10(3) kg/L) in the presence of HA. This improvement was attributed to the adsorption of pyrene-HA complexes. PVPcoS-MMT was most efficient in removing pyrene (k(d) = 1.1 × 10(4) kg/L, >95% removal) which was explained in terms of specific π donor-π acceptor interactions. Pyrene uptake by column filters of GAC reached ~50% and decreased to ~30% in the presence of HA. Pyrene removal by the PVPcoS-MMT filter was significantly higher (100-85% removal), exhibiting only a small decrease in the presence of HA. The utilization of HA as an enhancing agent in pollutant removal is novel and of major importance in water treatment. 相似文献
86.
Kawakubo Masateru Moriyama Daichi Yamasaki Yuzo Abe Kohtaro Hosokawa Kazuya Moriyama Tetsuhiro Triadyaksa Pandji Wibowo Adi Nagao Michinobu Arai Hideo Nishimura Hiroshi Kadokami Toshiaki 《Magma (New York, N.Y.)》2022,35(6):911-921
Magnetic Resonance Materials in Physics, Biology and Medicine - We propose a deep learning-based fully automatic right ventricle (RV) segmentation technique that targets radially reconstructed... 相似文献
87.
Hayit Greenspan Adi T Pinhas 《IEEE transactions on information technology in biomedicine》2007,11(2):190-202
This paper presents an image representation and matching framework for image categorization in medical image archives. Categorization enables one to determine automatically, based on the image content, the examined body region and imaging modality. It is a basic step in content-based image retrieval (CBIR) systems, the goal of which is to augment text-based search with visual information analysis. CBIR systems are currently being integrated with picture archiving and communication systems for increasing the overall search capabilities and tools available to radiologists. The proposed methodology is comprised of a continuous and probabilistic image representation scheme using Gaussian mixture modeling (GMM) along with information-theoretic image matching via the Kullback-Leibler (KL) measure. The GMM-KL framework is used for matching and categorizing X-ray images by body regions. A multidimensional feature space is used to represent the image input, including intensity, texture, and spatial information. Unsupervised clustering via the GMM is used to extract coherent regions in feature space that are then used in the matching process. A dominant characteristic of the radiological images is their poor contrast and large intensity variations. This presents a challenge to matching among the images, and is handled via an illumination-invariant representation. The GMM-KL framework is evaluated for image categorization and image retrieval on a dataset of 1500 radiological images. A classification rate of 97.5% was achieved. The classification results compare favorably with reported global and local representation schemes. Precision versus recall curves indicate a strong retrieval result as compared with other state-of-the-art retrieval techniques. Finally, category models are learned and results are presented for comparing images to learned category models. 相似文献
88.
Zero-knowledge proofs of identity 总被引:25,自引:2,他引:23
In this paper we extend the notion of interactive proofs of assertions to interactive proofs of knowledge. This leads to the
definition of unrestricted input zero-knowledge proofs of knowledge in which the prover demonstrates possession of knowledge
without revealing any computational information whatsoever (not even the one bit revealed in zero-knowledge proofs of assertions).
We show the relevance of these notions to identification schemes, in which parties prove their identity by demonstrating their
knowledge rather than by proving the validity of assertions. We describe a novel scheme which is provably secure if factoring
is difficult and whose practical implementations are about two orders of magnitude faster than RSA-based identification schemes.
The advantages of thinking in terms of proofs of knowledge rather than proofs of assertions are demonstrated in two efficient
variants of the scheme: unrestricted input zero-knowledge proofs of knowledge are used in the construction of a scheme which
needs no directory; a version of the scheme based on parallel interactive proofs (which are not known to be zero knowledge)
is proved secure by observing that the identification protocols are proofs of knowledge. 相似文献
89.
A validation study of the Keyboard Personal Computer Style instrument (K-PeCS) for use with children
This study examines a potential instrument for measurement of typing postures of children. This paper describes inter-rater, test-retest reliability and concurrent validity of the Keyboard Personal Computer Style instrument (K-PeCS), an observational measurement of postures and movements during keyboarding, for use with children. Two trained raters independently rated videos of 24 children (aged 7-10 years). Six children returned one week later for identifying test-retest reliability. Concurrent validity was assessed by comparing ratings obtained using the K-PECS to scores from a 3D motion analysis system. Inter-rater reliability was moderate to high for 12 out of 16 items (Kappa: 0.46 to 1.00; correlation coefficients: 0.77-0.95) and test-retest reliability varied across items (Kappa: 0.25 to 0.67; correlation coefficients: r = 0.20 to r = 0.95). Concurrent validity compared favourably across arm pathlength, wrist extension and ulnar deviation. In light of the limitations of other tools the K-PeCS offers a fairly affordable, reliable and valid instrument to address the gap for measurement of typing styles of children, despite the shortcomings of some items. However further research is required to refine the instrument for use in evaluating typing among children. 相似文献
90.
Transactional memory (TM) is an emerging concurrent programming abstraction. Numerous software-based transactional memory (STM) implementations have been developed in recent years. STM implementations must guarantee transaction atomicity and isolation. In order to ensure progress, an STM implementation must resolve transaction collisions by consulting a contention manager (CM). 相似文献