全文获取类型
收费全文 | 2565篇 |
免费 | 63篇 |
国内免费 | 7篇 |
专业分类
电工技术 | 144篇 |
综合类 | 6篇 |
化学工业 | 630篇 |
金属工艺 | 51篇 |
机械仪表 | 38篇 |
建筑科学 | 40篇 |
矿业工程 | 1篇 |
能源动力 | 95篇 |
轻工业 | 207篇 |
水利工程 | 7篇 |
石油天然气 | 2篇 |
无线电 | 246篇 |
一般工业技术 | 395篇 |
冶金工业 | 516篇 |
原子能技术 | 58篇 |
自动化技术 | 199篇 |
出版年
2023年 | 13篇 |
2022年 | 13篇 |
2021年 | 50篇 |
2020年 | 18篇 |
2019年 | 22篇 |
2018年 | 31篇 |
2017年 | 29篇 |
2016年 | 42篇 |
2015年 | 36篇 |
2014年 | 42篇 |
2013年 | 99篇 |
2012年 | 77篇 |
2011年 | 98篇 |
2010年 | 77篇 |
2009年 | 108篇 |
2008年 | 100篇 |
2007年 | 111篇 |
2006年 | 111篇 |
2005年 | 78篇 |
2004年 | 65篇 |
2003年 | 73篇 |
2002年 | 53篇 |
2001年 | 59篇 |
2000年 | 64篇 |
1999年 | 57篇 |
1998年 | 245篇 |
1997年 | 133篇 |
1996年 | 115篇 |
1995年 | 54篇 |
1994年 | 68篇 |
1993年 | 78篇 |
1992年 | 39篇 |
1991年 | 34篇 |
1990年 | 33篇 |
1989年 | 33篇 |
1988年 | 21篇 |
1987年 | 22篇 |
1986年 | 19篇 |
1985年 | 24篇 |
1984年 | 18篇 |
1983年 | 19篇 |
1982年 | 20篇 |
1981年 | 21篇 |
1980年 | 12篇 |
1979年 | 21篇 |
1978年 | 15篇 |
1977年 | 13篇 |
1976年 | 21篇 |
1975年 | 5篇 |
1973年 | 12篇 |
排序方式: 共有2635条查询结果,搜索用时 31 毫秒
81.
Hiroshige Matsuoka Koji Oka Yusuke Yamashita Fumihiro Saeki Shigehisa Fukui 《Microsystem Technologies》2011,17(5-7):983-990
Thermocapillary deformations of an ultra-thin liquid film caused by temperature distribution were three-dimensionally analyzed using the unsteady and linearized long wave equation considering the temperature and film thickness dependence of surface tension. The temperature and film thickness dependence equation for the surface tension of a liquid was firstly established. The temperature dependence of the surface tension was obtained experimentally using a surface tensiometer and the film thickness dependence was obtained theoretically from the corrected van der Waals pressure equation for a symmetric multilayer system. Time evolutions of depression and groove of the ultra-thin liquid film caused by local heating were obtained quantitatively. 相似文献
82.
83.
Recently, the size of solder bump interconnects have been significantly reduced with the advent of high-density packaging,
and thus the evaluation of electromigration in solder bumps has become necessary. The present paper proposes a simple method
to test the electromigration resistance of Pb-free solders. One of the key points of the present method is the fabrication
of a simple solder sample that can produce sufficient current density to cause electromigration. Moreover, the actual local
temperature of a small area subjected to electromigration in the sample was measured by a direct method. A right-angled diamond-shaped
hole was introduced in a thin film of solder using a focused-ion-beam system. A direct current was supplied to the film far
from the hole, perpendicular to the diagonal of the hole. In this way, the current density was concentrated near to the corner
of the hole, and the value of this was obtained through a theoretical analysis. It was noted that the steady temperature in
the film along a line extending from the diagonal, remained constant, although the current density decreased gradually far
from the corner. Therefore, the temperature at a position near the corner, where electromigration takes place, can easily
be found by measuring the temperature far from the corner. The temperature was measured directly under current flow conditions
by utilizing the chemical reagents with known melting points. Finally, by measuring the ratio of hillock volume to the time
for the current supply as a measure of the atomic flux divergence due to electromigration, the corresponding resistances of
some Pb-free solders to electromigration were evaluated. 相似文献
84.
85.
This paper presents a tabu search approach for scheduling jobs on identical parallel machines with the objective of minimizing the mean tardiness. Initially, we consider a basic tabu search that uses short term memory only. Local search is performed on a neighborhood defined by two types of moves. Insert moves consist of transferring each job from one machine to another and swap moves are those obtained by exchanging each pair of jobs between two machines. Next, we analyze the incorporation of two diversification strategies with the aim of exploring unvisited regions of the solution space. The first strategy uses long term memory to store the frequency of the moves executed throughout the search and the second makes use of influential moves. Computational tests are performed on problems with up to 10 machines and 150 jobs. The heuristic performance is evaluated through a lower bound given by Lagrangean relaxation. A comparison is also made with respect to the best constructive heuristic reported in the literature. 相似文献
86.
Real robots should be able to adapt autonomously to various environments in order to go on executing their tasks without breaking
down. They achieve this by learning how to abstract only useful information from a huge amount of information in the environment
while executing their tasks. This paper proposes a new architecture which performs categorical learning and behavioral learning
in parallel with task execution. We call the architectureSituation Transition Network System (STNS). In categorical learning, it makes a flexible state representation and modifies it according to the results of behaviors.
Behavioral learning is reinforcement learning on the state representation. Simulation results have shown that this architecture
is able to learn efficiently and adapt to unexpected changes of the environment autonomously.
Atsushi Ueno, Ph.D.: He is a research associate in the Artificial Intelligence Laboratory at the Graduate School of Information Science at the
Nara Institute of Science and Technology (NAIST). He received the B.E., the M.E., and the Ph.D. degrees in aeronautics and
astronautics from the University of Tokyo in 1991, 1993, and 1997 respectively. His research interest is robot learning and
autonomous systems. He is a member of Japan Association for Artificial Intelligence (JSAI).
Hideaki Takeda, Ph.D.: He is an associate professor in the Artificial Intelligence Laboratory at the Graduate School of Information Science at the
Nara Institute of Science and Technology (NAIST). He received his Ph.D. in precision machinery engineering from the University
of Tokyo in 1991. He has conducted research on a theory of intelligent computer-aided design systems, in particular experimental
study and logical formalization of engineering design. He is also interested in multiagent architectures and ontologies for
knowledge base systems. 相似文献
87.
We investigate the static and dynamic behavior of vortices in a pin-free superconductor. A diffraction pattern is observed in the critical currentJ
cvs. applied fieldH
parallel to the surface of a granular Al film. When one vortex chain is formed in the film,J
cbecomes nearly equal to zero, which verifies that the sample is actually pin-free. An interaction between a radiofrequency current and moving vortices occurs, and theI–V curve shows peculiar nonlinear effects such as real negative resistance. The results are analogous to dc and ac Josephson effects. 相似文献
88.
A modified pulse-heating method is proposed to improve the accuracy of measurement of the hemispherical total emissivity, specific heat capacity, and electrical resistivity of electrically conductive materials at high temperatures. The proposed method is based on the analysis of a series of rapid resistive self-heating experiments on a sample heated at different temperature rates. The method is used to measure the three properties of the IG-110 grade of isotropic graphite at temperatures from 850 to 1800 K. The problem of the extrinsic heating-rate effect, which reduces the accuracy of the measurements, is successfully mitigated by compensating for the generally neglected experimental error associated with the electrical measurands (current and voltage). The results obtained by the proposed method can be validated by the linearity of measured quantities used in the property determinations. The results are in reasonably good agreement with previously published data, which demonstrate the suitability of the proposed method, in particular, to the resistivity and total emissivity measurements. An interesting result is the existence of a minimum in the emissivity of the isotropic graphite at around 1120 K, consistent with the electrical resistivity results. 相似文献
89.
Many sorting algorithms have been studied in the past, but there are only a few algorithms that can effectively exploit both single‐instruction multiple‐data (SIMD) instructions and thread‐level parallelism. In this paper, we propose a new high‐performance sorting algorithm, called aligned‐access sort (AA‐sort), that exploits both the SIMD instructions and thread‐level parallelism available on today's multicore processors. Our algorithm consists of two phases, an in‐core sorting phase and an out‐of‐core merging phase. The in‐core sorting phase uses our new sorting algorithm that extends combsort to exploit SIMD instructions. The out‐of‐core algorithm is based on mergesort with our novel vectorized merging algorithm. Both phases can take advantage of SIMD instructions. The key to high performance is eliminating unaligned memory accesses that would reduce the effectiveness of SIMD instructions in both phases. We implemented and evaluated the AA‐sort on PowerPC 970MP and Cell Broadband Engine platforms. In summary, a sequential version of the AA‐sort using SIMD instructions outperformed IBM's optimized sequential sorting library by 1.8 times and bitonic mergesort using SIMD instructions by 3.3 times on PowerPC 970MP when sorting 32 million random 32‐bit integers. Also, a parallel version of AA‐sort demonstrated better scalability with increasing numbers of cores than a parallel version of bitonic mergesort on both platforms. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
90.
Low-Ag-based Pb-free solder and its evaluation for electromigration (EM) reliability are research areas of active development. This paper studies the effect of adding Ni and Ge microelements on the EM behavior of low-Ag-based SnAgCu solder. Comparative measurements of the EM resistance of Sn1.0Ag0.5Cu (SAC) and Sn1.0Ag0.5Cu0.07Ni0.01Ge (SACNG) solders (in wt?%) were conducted. In these experiments, SACNG showed a higher EM resistance than SAC. It was concluded that adding Ni and Ge enhanced the EM resistance of low-Ag-based SnAgCu solders. This shows the same effect of Ni and Ge on the EM resistance as that which has been reported for Sn3.5Ag0.5Cu solder. An analysis of these observations suggests that grain boundary sliding plays a dominant role in stress relaxation and causes hillock growth. Based on this assumption, a possible mechanism was proposed to explain the effects of Ni and Ge on the EM resistance of SnAgCu solder. 相似文献