全文获取类型
收费全文 | 718篇 |
免费 | 23篇 |
专业分类
电工技术 | 19篇 |
化学工业 | 192篇 |
金属工艺 | 7篇 |
机械仪表 | 18篇 |
建筑科学 | 7篇 |
能源动力 | 24篇 |
轻工业 | 69篇 |
水利工程 | 2篇 |
无线电 | 56篇 |
一般工业技术 | 171篇 |
冶金工业 | 102篇 |
原子能技术 | 28篇 |
自动化技术 | 46篇 |
出版年
2023年 | 3篇 |
2022年 | 6篇 |
2021年 | 28篇 |
2020年 | 8篇 |
2019年 | 3篇 |
2018年 | 13篇 |
2017年 | 11篇 |
2016年 | 11篇 |
2015年 | 12篇 |
2014年 | 17篇 |
2013年 | 28篇 |
2012年 | 11篇 |
2011年 | 29篇 |
2010年 | 28篇 |
2009年 | 34篇 |
2008年 | 35篇 |
2007年 | 26篇 |
2006年 | 28篇 |
2005年 | 18篇 |
2004年 | 14篇 |
2003年 | 23篇 |
2002年 | 23篇 |
2001年 | 18篇 |
2000年 | 18篇 |
1999年 | 14篇 |
1998年 | 55篇 |
1997年 | 29篇 |
1996年 | 20篇 |
1995年 | 20篇 |
1994年 | 16篇 |
1993年 | 8篇 |
1992年 | 5篇 |
1991年 | 8篇 |
1990年 | 9篇 |
1989年 | 12篇 |
1988年 | 11篇 |
1987年 | 5篇 |
1986年 | 6篇 |
1985年 | 8篇 |
1984年 | 7篇 |
1983年 | 3篇 |
1982年 | 6篇 |
1981年 | 7篇 |
1980年 | 8篇 |
1979年 | 7篇 |
1978年 | 6篇 |
1977年 | 6篇 |
1976年 | 8篇 |
1975年 | 3篇 |
1972年 | 3篇 |
排序方式: 共有741条查询结果,搜索用时 350 毫秒
21.
22.
Adrian Hernandez-Becerril Mariko Nakano-Miyatake Marco Ramirez-Tachiquin Hector Perez-Meana 《通讯和计算机》2013,(5):649-660
Recently, a multisecret sharing scheme for secret color images among a set of users was proposed, which allows that each participant to share secret color images with the rest of participants in such way that all of them can recover all secret color images only if all participants pool their shares. In this work a parallel implementation of the cellular automata-based multisecret sharing scheme is proposed, in which the technology of CUDA (Compute Unified Device Architecture) is used in parallelization, taking advantage that each cell of cellular automata can be processed independently. The processing time of the proposed scheme is analyzed and it is proved that the proposed parallel algorithm using the CUDA structure is more than 12 times faster than the conventional sequential algorithm. This reduction of temporal complexity allows the practical use of the secret sharing scheme in many information security fields. 相似文献
23.
Yoshihisa Shinya Kenji Kamiya Tomoyuki Toyoda Yasumi Endo Nelly Soudakova Hirofumi Kondo 《Journal of the Society for Information Display》2009,17(4):331-336
Abstract— The display used in current cell phones has an air gap between the cover glass and the liquid‐crystal‐display (LCD) module to prevent the LCD glass from being damaged. Reflections at the boundaries of the air gap cause a reduction in the LCD luminance and contrast. To address this problem, a newly proposed LCD structure has been investigated. The “Super View Resin (SVR),” a transparent elastic resin which improves the shock resistance and visibility of the LCD, has been developed. Filling the air gap between the cover glass and LCD module with a refractive‐index‐matching resin solves the light‐reflection problem inherent in the use of a reinforced cover‐glass lens. Moreover, the elastic filler works as a damper, reducing any external shock, which prevents not only the cover glass and LCD module from being damaged, but also the glass from being shattered when it is broken. 相似文献
24.
Optical Properties of Self‐Assembled Cellulose Nanocrystals Films Suspended at Planar–Symmetrical Interfaces
下载免费PDF全文
![点击此处可从《Small (Weinheim an der Bergstrasse, Germany)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Blaise L. Tardy Mariko Ago Jiaqi Guo Maryam Borghei Tero Kämäräinen Orlando J. Rojas 《Small (Weinheim an der Bergstrasse, Germany)》2017,13(47)
Hierarchically structured materials comprising rod‐like, chiral, nanoparticles are commonly encountered in nature as they can form assemblies with exceptional optical and mechanical characteristics. These include cellulose nanocrystals (CNCs), which have a large potential for the fabrication of bioinspired materials mimicking those advanced properties. Fine‐tuning the optomechanical properties of assemblies obtained from CNCs hinges on the transformations from suspensions of liquid crystals to long‐range order in the dry state. So far, associated transitions have been studied using trivial interfaces such as planar substrates. Such transitions are explored as they evolve onto meshed supports. The meshed substrate offers a complex topology, as is encountered in nature, for the formation of CNCs films. The CNCs self‐assembly occurs under confinement and support of the framework bounding the mesh openings. This leads to coexisting suspended and supported nanoparticle layers exhibiting nematic and/or chiral nematic order. Optical microscopy combined with crossed polarizers indicate that the formation of the suspended films occurs via intermediate gelation or kinetic arrest of CNCs across the mesh's open areas. The formation of self‐standing, ultrathin films of CNCs with tunable optical properties, such as selective reflections in the visible range (structural color), is demonstrated by using the presented simple and scalable approach. 相似文献
25.
Contrary to popular belief, biologists discovered that worker ants are really not all hardworking. It has been found that in three separate 30-strong colonies of black Japanese ants (Myrmecina nipponica), about 20% of worker ants are diligent, 60% are ordinary, and 20% are lazy. That is called 20:60:20 rule. Though they are lazy, biologists suggested that lazy worker ants could be contributing something to the colony that is yet to be determined. In our last research, we used CHC (cross generational elitist selection, heterogeneous recombination, and cataclysmic mutation) with the worker ants’ rule (WACHC) aiming at solving optimization problems in changing environments. CHC is a nontraditional genetic algorithm (GA) which combines a conservative selection strategy that always preserves the best individuals found so far with a radical (highly disruptive) recombination operator. In our last research, we verified that WACHC performs better than CHC in only one case of fully changing environment. In this paper, we further discuss our proposed WACHC dealing with changing environment problems with varying degree of difficulty, compare our proposal with hypermutation GA which is also proposed for dealing with changing environment problems, and discuss the difference between our proposal and ant colony optimization algorithms. 相似文献
26.
Khairul Salleh Hiroaki Seki Yoshitsugu Kamiya Masatoshi Hikizu 《Artificial Life and Robotics》2008,12(1-2):142-147
Manipulating deformable objects like clothes, plastic, and paper by a robot is very challenging. This paper focuses on clothes
manipulation as an example. A tracing manipulation method is used here to find a corner of the clothes. In this paper, tracing
refers to tracing the clothes’ edge, with the robot’s movement based on feedback from sensors. One difficulty during this
edge tracing is to make the robot trace smoothly and speedily without dropping the clothes in the process. This is due to
the fact that deformable objects are sensitive to contact forces. A solution to this problem is to design a special robot
gripper that can trace the clothes without having to worry about the clothes slipping away. In this paper, the development
of inchworm-type grippers is proposed. Two sets of grippers inside a robot hand will allow the robot to trace the clothes
more freely because there will always be a gripper firmly holding the clothes at any time. A unique tracing method for towel
spreading using the inchworm grippers is also discussed. Experimental results have demonstrated the effectiveness of both
the proposed grippers and also the algorithm.
This work was presented in part at the 12th International Symposium on Artificial Life and Robotics, Oita, Japan, January
25–27, 2007 相似文献
27.
In this study, a three-point bendJ lc fracture-toughness test was carried out using four types of structural steels at room temperature. The values of (γ p)V, which represent the width of the region where the voids are located just ahead of the crack tip, were measured by Beacham's method [9] with the help of a scanning electron microscope (SEM). The experimental (γ p) values and the theoretical values obtained using the finite element method (FEM) or calculated fromK at initiation are in good agreement. It was found that there is a certain linear relationship between (γ p)Vand the stretched zone width (SZW), and an experimental relationship betweenJ lc andσ flow·(γ p)V which may be expressed by the following equation: $$J_{lc} = 44.1 + 0.35\sigma _{{\text{flow}}} \cdot (\gamma _{\text{p}} )V_c KJ$$ whereσ flow is the average value of the yield stress and the ultimate tensile strength. (γ p)V c represents the critical value of (γ p)V. The numerical constant 44.1 kJ m?2 is considered to be aJ lc value for brittle fracture of the material tested, according to the authors' previous results. It is possible to calculateJ lc if (γ p)V c can be measured. 相似文献
28.
Yan Liu Shigenori Mitsushima Ken-ichiro Ota Nobuyuki Kamiya 《Electrochimica acta》2006,51(28):6503-6509
The electro-oxidation of dimethyl ether (DME) on PtMe/Cs (Me = Ru, Sn, Mo, Cr, Ni, Co, and W) and Pt/C electro-catalysts were investigated in an aqueous half-cell, and compared to the methanol oxidation. The addition of a second metal enhanced the tolerance of Pt to the poisonous species during the DME oxidation reaction (DOR). The PtRu/C electro-catalyst showed the best electro-catalytic activity and the highest tolerance to the poisonous species in the low over-potential range (<0.55 V, 50 °C) among the binary electro-catalysts and the Pt/C, but at the higher potential (>ca. 0.55 V, 50 °C), the Pt/C behaved better than PtRu/C. The apparent activation energy for the DOR decreased in the order: PtRu/C (57 kJ mol−1) > Pt3Sn/C (48 kJ mol−1) ≈ Pt/C (46 kJ mol−1). On the other hand, the activation energy for the MOR showed a different turn, decreased in the following order: Pt/C (43 kJ mol−1) > Pt3Sn/C (35 kJ mol−1) ≈ PtRu/C (34 kJ mol−1). The temperature dependence of the DOR was greater than that of the oxidation of methanol (MOR) on the PtRu/C. 相似文献
29.
Applying the concept of materials design for transparent conductive oxides to layered oxychalcogenides, several p-type and n-type layered oxychalcogenides were proposed as wide-gap semiconductors and their basic optical and electrical properties were examined. The layered oxychalcogenides are composed of ionic oxide layers and covalent chalcogenide layers, which bring wide-gap and conductive properties to these materials, respectively. The electronic structures of the materials were examined by normal/inverse photoemission spectroscopy and energy band calculations. The results of the examinations suggested that these materials possess unique features more than simple wide-gap semiconductors. Namely, the layered oxychalcogenides are considered to be extremely thin quantum wells composed of the oxide and chalcogenide layers or 2D chalcogenide crystals/molecules embedded in an oxide matrix. Observation of step-like absorption edges, large band gap energy and large exciton binding energy demonstrated these features originating from 2D density of states and quantum size effects in these layered materials. 相似文献
30.
Four mechanical parameters of physical vapor-deposited (PVD) hard coatings were obtained, which were the residual strain, Young's modulus, film toughness, and interface toughness, concerning titanium aluminum nitride (TiAlN) and titanium nitride (TiN) coatings deposited on WC-Co substrates. The results were quantitatively compared with the author's previous trials for the case of chemical vapor-deposited (CVD) diamond coatings. Due to the significant difference in the mechanical properties between PVD hard coatings and CVD diamond coatings, it was necessary to develop new experimental techniques, which could properly evaluate those parameters for the case of PVD hard coatings. As a conclusion, film toughness of PVD hard coatings was surprisingly brittle. It was an order of magnitude smaller than that of CVD diamond coatings. In contrast, no significant difference was found in interface toughness between these different kinds of coatings. Concerning the residual strain, TiN had far larger level than the other two. These differences in mechanical properties were further discussed in relation to the difference in their wear behavior. 相似文献