全文获取类型
收费全文 | 978篇 |
免费 | 26篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 5篇 |
综合类 | 1篇 |
化学工业 | 237篇 |
金属工艺 | 24篇 |
机械仪表 | 31篇 |
建筑科学 | 50篇 |
矿业工程 | 2篇 |
能源动力 | 50篇 |
轻工业 | 89篇 |
水利工程 | 4篇 |
石油天然气 | 1篇 |
无线电 | 58篇 |
一般工业技术 | 194篇 |
冶金工业 | 144篇 |
原子能技术 | 8篇 |
自动化技术 | 107篇 |
出版年
2022年 | 8篇 |
2021年 | 22篇 |
2020年 | 10篇 |
2019年 | 10篇 |
2018年 | 24篇 |
2017年 | 19篇 |
2016年 | 20篇 |
2015年 | 12篇 |
2014年 | 21篇 |
2013年 | 49篇 |
2012年 | 37篇 |
2011年 | 47篇 |
2010年 | 32篇 |
2009年 | 30篇 |
2008年 | 38篇 |
2007年 | 42篇 |
2006年 | 34篇 |
2005年 | 39篇 |
2004年 | 19篇 |
2003年 | 21篇 |
2002年 | 21篇 |
2001年 | 16篇 |
2000年 | 15篇 |
1999年 | 21篇 |
1998年 | 53篇 |
1997年 | 29篇 |
1996年 | 15篇 |
1995年 | 14篇 |
1994年 | 15篇 |
1993年 | 17篇 |
1992年 | 13篇 |
1991年 | 13篇 |
1990年 | 10篇 |
1989年 | 10篇 |
1988年 | 8篇 |
1987年 | 7篇 |
1986年 | 8篇 |
1985年 | 11篇 |
1984年 | 9篇 |
1983年 | 14篇 |
1982年 | 10篇 |
1981年 | 14篇 |
1980年 | 8篇 |
1977年 | 10篇 |
1976年 | 13篇 |
1974年 | 8篇 |
1972年 | 13篇 |
1970年 | 11篇 |
1969年 | 12篇 |
1968年 | 10篇 |
排序方式: 共有1005条查询结果,搜索用时 15 毫秒
31.
Summary The amount of nondeterminism in a nondeterministic finite automaton (NFA) is measured by counting the minimal number of guessing points a string w has to pass through on its way to an accepting state. NFA's with more nondeterminism can achieve greater savings in the number of states over their deterministic counterparts than NFA's with less nondeterminism. On the other hand, for some nontrivial infinite regular languages a deterministic finite automaton (DFA) can already be quite succinct in the sense that NFA's need as many states (and even context-free grammars need as many nonterminals) as the minimal DFA has states.This research was supported in part by the National Science Foundation under Grant No. MCS 76-10076 相似文献
32.
A transformation is presented which converts any pushdown automaton (PDA)M
0 withn
0 states andp
0 stack symbols into an equivalent PDAM withn states and n
0
/n2
p
0 stack symbols into an equivalent ofn, 1n
0. This transformation preserves realtime behavior but not derterminism. The transformation is proved to be the best possible one in the following sense: for each choice of the parametersn
0 + 1 stack symbols for any desired value realtime PDAM
0 such that any equivalent PDAM (whether realtime or not) havingn states must have at least (n
0
/n)2 p0 stack symbols. Furthermore, the loss of deterministic behavior cannot be avoided, since for each choice ofn
0 andp
0, there is a deterministic PDAM
0 such that no equivalent PDAM with fewer states can be deterministic.This research was supported in part by the National Science Foundation under Grants MCS76-10076 and MCS76-10076A01. 相似文献
33.
Yanka Jeliazova Michael Kayser Beate Mildner Achim Walter Hassel Detlef Diesing 《Thin solid films》2006,500(1-2):330-335
The dielectric breakdown of thin (d = 3–4 nm) aluminium and tantalum oxide films was investigated by means of current voltage plots in metal/insulator/metal systems. Dielectric breakdown field strengths, EDB, of 0.6 GV m− 1 were found for both oxide types at room temperature. Differences appear in the temperature dependence of EDB. Tantalum oxide films show an unchanged breakdown behaviour for temperatures up to 420 K while aluminium oxide films lose already 80% of their EDB value in the same temperature range. Time-resolved investigations of the electric breakdown revealed intermediate states of both oxide types which were stable for several ms being characterized by an enhanced tunnel current. The breakdown voltage clearly scales with the oxide thickness for both oxide types. 相似文献
34.
35.
G. Schmidl G. Andrä J. Bergmann A. Gawlik I. Höger S. Anders F. Schmidl V. Tympel F. Falk 《Journal of Materials Science》2013,48(12):4177-4182
CW-diode laser crystallization of amorphous silicon (a-Si) deposited by sputtering or by electron beam evaporation onto different substrates (glass without or with SiNx or SiO2 intermediate layers) is investigated. The resulting grain sizes and orientations are characterized by electron backscatter diffraction, optical microscopy, and x-ray diffraction. We demonstrate that 200 nm thick sputtered a-Si layers can be crystallized on all of the used substrates to result in grains from 1 up to 100 μm in size, depending on the laser irradiation parameters (intensity, exposure time). Electron beam evaporated a-Si films can be crystallized only on sputtered SiNx intermediate layers to result in grains of 100 μm in size. Similar crystallographic film properties follow from laser treatment if the product of laser peak intensity and square root of exposure time is kept constant, independent of the scan velocity used. A high fraction of preferred (100)-oriented silicon grains can only be observed for samples with crystallites less than 10 μm in size. 相似文献
36.
37.
Detlef Hühnlein 《Datenschutz und Datensicherheit - DuD》2014,38(4):217-217
38.
Junying Liu Rui Zhang Itaru Osaka Sarada Mishra Anna E. Javier Detlef‐M. Smilgies Tomasz Kowalewski Richard D. McCullough 《Advanced functional materials》2009,19(21):3427-3434
New solution processable 4‐(2‐hexyldecan)‐4H‐bisthieno[2,3‐d:3′,2′‐b]pyrrole and 4,4′‐dialkyl‐2,2′‐bithiazole‐based copolymers (PBTzDTPs) are synthesized with excellent FET performance. These novel copolymers have considerable potential in printable electronics as they have high charge carrier mobilities, excellent air stability, good solution processibility, and no requirement for post‐deposition thermal annealing, all requirements for this field of application. The thin film transistors fabricated from PBTzDTPs achieve field effect mobilities as high as 0.14 cm2 V?1 s?1 with current on/off ratios up to 106 without thermal annealing. In addition, the devices exhibit stable performance in air, showing no significant degradation over 60 days. Moreover, the polymers described here provide an excellent example of the systems in which higher mobility performance does not require higher crystalline, long‐range ordered structures. Such a system appears to be particularly promising for rapid fabrication techniques, where kinetic conditions usually prevent the development of long‐range order. 相似文献
39.
Widely Tunable Morphologies in Block Copolymer Thin Films Through Solvent Vapor Annealing Using Mixtures of Selective Solvents 下载免费PDF全文
Michelle A. Chavis Detlef‐M. Smilgies Ulrich B. Wiesner Christopher K. Ober 《Advanced functional materials》2015,25(20):3057-3065
Thin films of block copolymers are extremely attractive for nanofabrication because of their ability to form uniform and periodic nanoscale structures by microphase separation. One shortcoming of this approach is that to date the design of a desired equilibrium structure requires synthesis of a block copolymer de novo within the corresponding volume ratio of the blocks. In this work, solvent vapor annealing in supported thin films of poly(2‐hydroxyethyl methacrylate)‐block‐poly(methyl methacrylate) [PHEMA‐b‐PMMA] by means of grazing incidence small angle X‐ray scattering (GISAXS) is investigated. A spin‐coated thin film of a lamellar block copolymer is solvent vapor annealed to induce microphase separation and improve the long‐range order of the self‐assembled pattern. Annealing in a mixture of solvent vapors using a controlled volume ratio of solvents, which are chosen to be preferential for each block, enables selective formation of ordered lamellae, gyroid, hexagonal, or spherical morphologies from a single‐block copolymer with a fixed volume fraction. The selected microstructure is then kinetically trapped in the dry film by rapid drying. This paper describes what is thought to be the first reported case where in situ methods are used to study the transition of block copolymer films from one initial disordered morphology to four different ordered morphologies, covering much of the theoretical diblock copolymer phase diagram. 相似文献
40.
Chemikalienfreie Bekämpfung von Holzschädlingen durch dielektrische Erwärmung mit Radiowellen und Mikrowellen 下载免费PDF全文
Christian Hoyer Christian Pfütze Dr. Rudy Plarre Dr. Ulf Trommler Steffen Steinbach Kerstin Klutzny Dr. Frank Holzer Carsten Rabe Björn Höhlig Prof. Frank‐Dieter Kopinke Prof. Detlef Schmidt Dr. Ulf Roland 《化学,工程师,技术》2014,86(8):1187-1197
Thermal pest control requires long treatment times due to the low thermal conductivity of wood and may lead to the formation of cracks. Here, the thermal treatment with radio waves as well as microwaves has been studied. The direct dielectric heating has the advantage of a good homogeneity. The obtained temperature profiles for radio waves were more homogeneous compared to microwaves. Detailed studies showed that elimination of pests was not related to the application of the electromagnetic field itself, but due to the temperature increase. 相似文献