全文获取类型
收费全文 | 1427篇 |
免费 | 91篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 7篇 |
综合类 | 2篇 |
化学工业 | 328篇 |
金属工艺 | 61篇 |
机械仪表 | 71篇 |
建筑科学 | 17篇 |
能源动力 | 73篇 |
轻工业 | 150篇 |
水利工程 | 3篇 |
石油天然气 | 2篇 |
无线电 | 201篇 |
一般工业技术 | 352篇 |
冶金工业 | 76篇 |
原子能技术 | 6篇 |
自动化技术 | 172篇 |
出版年
2024年 | 2篇 |
2023年 | 16篇 |
2022年 | 28篇 |
2021年 | 47篇 |
2020年 | 35篇 |
2019年 | 29篇 |
2018年 | 37篇 |
2017年 | 47篇 |
2016年 | 42篇 |
2015年 | 39篇 |
2014年 | 69篇 |
2013年 | 83篇 |
2012年 | 83篇 |
2011年 | 132篇 |
2010年 | 99篇 |
2009年 | 89篇 |
2008年 | 89篇 |
2007年 | 71篇 |
2006年 | 57篇 |
2005年 | 53篇 |
2004年 | 48篇 |
2003年 | 57篇 |
2002年 | 38篇 |
2001年 | 40篇 |
2000年 | 20篇 |
1999年 | 25篇 |
1998年 | 29篇 |
1997年 | 21篇 |
1996年 | 15篇 |
1995年 | 19篇 |
1994年 | 12篇 |
1993年 | 12篇 |
1992年 | 10篇 |
1991年 | 8篇 |
1990年 | 4篇 |
1989年 | 2篇 |
1988年 | 3篇 |
1987年 | 3篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1981年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1972年 | 1篇 |
排序方式: 共有1521条查询结果,搜索用时 343 毫秒
991.
992.
Design of protective structures requires multiple functions and reasonable safety criteria according to target structures. Hardening is one of the common concept to protect facilities and people. A general concept of blast pressure mitigation by metal foams was proposed. In this paper, a composite panel with aluminum foams and steel skins is introduced. Aluminum foams have low density and are attractive materials to mitigate high-speed pressure by blast loads due to high-energy absorption capabilities. A steel skin with high energy absorption capacity can be effectively used to resist penetration at front surface of the barrier and debris risk at rear surface. Mechanical properties of the aluminum foam according to different densities were obtained by material tests. Three material models for concrete, steel and aluminum foam were utilized considering strain-rate effects. Using the derived material models, explicit analyses of the composite panels were performed and their performance was evaluated. The newly developed high strength foam showed higher yield strength and better energy absorption capacity resulting in lightweight protective panels. For high blast pressure, the combination of energy absorbing steel skin and relatively dense foam or thicker foam is more effective. 相似文献
993.
We demonstrate low-trap-density HfON film made by the molecular-atomic deposition (MAD) technique, which is an Ar/N2 plasma jet assisted physical vapor deposition process. This high-k HfON can be deposited on top of the nearly trap-free MAD-Si3N4 to form a single-side crested tunnel barrier. The Al/(HfON-Si3N4)/Si capacitor structure with HfON/Si3N4 stack as the tunnel barrier demonstrates steeper I-V slope than that of a single layer SiO2 with the same EOT, and is readily applicable to improve the programming speed and data retention of flash memories. 相似文献
994.
This paper focuses on the problem of scheduling jobs on parallel machines considering a job-splitting property. In this problem, it is assumed that a job can be split into a discrete number of subjobs and they are processed on parallel machines independently. A two-phase heuristic algorithm is suggested for the problem with the objective of minimizing total tardiness. In the first phase, an initial sequence is constructed by an existing heuristic method for the parallel-machine scheduling problem. In the second phase, each job is split into subjobs considering possible results of the split, and then jobs and subjobs are rescheduled on the machines using a certain method. To evaluate performance of the suggested algorithm, computational experiments are performed on randomly generated test problems. Results of the experiments show that the suggested algorithm performs better than an existing one. 相似文献
995.
Eun-Gi Shim Tae-Heum Nam Jung-Gu Kim Hyun-Soo Kim Seong-In Moon 《Metals and Materials International》2009,15(4):615-621
Safety concerns related to lithium-ion batteries have been the key obstacle to their application in hybrid electric vehicles.
Trioctyl Phosphate (TOP) and Cresyl Diphenyl Phosphate (CDP) were studied as potential flame-retarding additives for lithium-ion
batteries. The electrochemical performance and thermal stability of the additive-containing electrolytes, in combination with
a cell comprising a LiCoO2 cathode and Mesocarbon Microbeads (MCMB) anode, were tested in coin cells. Cyclic Voltammetry (CV), Differential Scanning
Calorimetry (DSC), Electrochemical Impedance Spectroscopy (EIS), and Scanning Electron Microscopy (SEM) were used for the
experimental analysis. The study results revealed that CDP addition at 5 wt.% improved the cell stability due to the lower
rate of the charge-transfer resistance increase over 30–50 cycles. CDP was demonstrated to be a better flame-retarding additive
than TOP. 相似文献
996.
Austenitic oxide dispersion strengthened (ODS) alloys containing 0.5 and 5 wt.% yttria were prepared from elemental powders (Fe–20% Ni–14% Cr–2.5% Mo–2.5% Al–2% Mn) by mechanical alloying. The powders were analyzed using X-ray diffraction (XRD), X-ray photoelectron spectroscopy and transmission electron microscopy (TEM), paying particular attention to the behavior of yttria. XRD and high-resolution TEM analyses show that yttria does not form a solid solution with austenite; unlike in ferritic ODS alloys, where it dissolves. Milling induces the formation of the thermodynamically favorable yttrium aluminum perovskite (YAP). Alumina from the aluminum powder in the starting blend, formed in the initial stages of milling using oxygen available from the other elemental powders, combines with yttria to form YAP. The yttria content does not affect alloy formation but reduces the crystallite size and strain significantly in the 5% yttria composition. TEM analysis of hot-pressed compacts reveals nanocrystalline particles of yttria, yttrium aluminum garnet and YAP. 相似文献
997.
998.
Highly Stretchable Resistive Pressure Sensors Using a Conductive Elastomeric Composite on a Micropyramid Array
下载免费PDF全文
![点击此处可从《Advanced materials (Deerfield Beach, Fla.)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
999.
Structural performance of composite joints using bent studs 总被引:3,自引:3,他引:0
A composite truss bridge is an efficient structural type where the merits of both the steel member and the prestressed concrete member are combined. The design of a connection for the truss bridge is of particular interest due to complex details resulting from concentrated forces at the composite joint. In this paper, experimental investigations were conducted to evaluate the performance of the joint with bent studs welded on a gusset plate. Push-out tests for static and fatigue loadings on a group stud connection were conducted to evaluate the direct shear strength and fatigue endurance of the joint. Because the joints are subject to various loading conditions, flexure-shear tests were also performed to verify the design provisions for the joints under a combination of tension and shear. In order to enhance the structural behavior of the connection, a bent shaped stud was proposed to increase the pull-out strength of the concrete slab. Test results showed that it is adequate to use Eurocode-4 for the evaluation of a shear connection which satisfies the requirement of minimum stud spacing specified in Eurocode-4. Since the shear load is concentrated at the joint structure of composite truss bridges, additional confining reinforcements are needed to enhance the horizontal shear strength of the shear connection. The design provision on the interaction of tension and shear for the joint structure gave conservative results. When the pyramid failure surface was assumed, internal studs had little effect on the pull-out strength of the joint. Constructability of the joint can be enhanced by decreasing the number of connectors and by strengthening the concrete slab through simplified design checks assuming four failure modes and their interactions. 相似文献
1000.
JeongYon Shim 《Artificial Life and Robotics》2009,14(4):535-538
This article proposes a memory retention strategy in a knowledge network structure in order to make a more efficient intelligent
system. The structure and management strategy of the memory have a great influence on the efficiency of the system. In this
approach, the concept of neutral energy is introduced, which is used to represent the state of the knowledge node. The energy
value of the node was designed to manage the memory retention and recall process in a brain-inspired system. This strategy
was applied to a virtual memory and tested with sample data. 相似文献