全文获取类型
收费全文 | 479篇 |
免费 | 27篇 |
专业分类
电工技术 | 12篇 |
化学工业 | 181篇 |
金属工艺 | 11篇 |
机械仪表 | 10篇 |
建筑科学 | 16篇 |
能源动力 | 24篇 |
轻工业 | 30篇 |
石油天然气 | 2篇 |
无线电 | 28篇 |
一般工业技术 | 102篇 |
冶金工业 | 10篇 |
原子能技术 | 7篇 |
自动化技术 | 73篇 |
出版年
2023年 | 8篇 |
2022年 | 4篇 |
2021年 | 18篇 |
2020年 | 11篇 |
2019年 | 15篇 |
2018年 | 18篇 |
2017年 | 8篇 |
2016年 | 21篇 |
2015年 | 18篇 |
2014年 | 21篇 |
2013年 | 35篇 |
2012年 | 41篇 |
2011年 | 30篇 |
2010年 | 21篇 |
2009年 | 24篇 |
2008年 | 23篇 |
2007年 | 16篇 |
2006年 | 12篇 |
2005年 | 15篇 |
2004年 | 13篇 |
2003年 | 11篇 |
2002年 | 6篇 |
2001年 | 4篇 |
2000年 | 6篇 |
1999年 | 1篇 |
1998年 | 4篇 |
1997年 | 3篇 |
1996年 | 5篇 |
1995年 | 4篇 |
1994年 | 3篇 |
1993年 | 2篇 |
1992年 | 1篇 |
1991年 | 5篇 |
1990年 | 6篇 |
1989年 | 5篇 |
1988年 | 8篇 |
1987年 | 7篇 |
1986年 | 10篇 |
1985年 | 2篇 |
1984年 | 9篇 |
1983年 | 7篇 |
1982年 | 4篇 |
1981年 | 6篇 |
1980年 | 5篇 |
1979年 | 5篇 |
1978年 | 1篇 |
1977年 | 2篇 |
1974年 | 1篇 |
1972年 | 1篇 |
排序方式: 共有506条查询结果,搜索用时 218 毫秒
11.
Graft copolymers of polybutadiene (PBD) onto poly(p-phenylene terephthalamide) (PPTA) were prepared by the nucleophilic substitution of N-metalated PPTA with telechelic PBD having bromide end groups. Block copolymers were synthesized by the condensation reaction of telechelic PBD having acid chloride end groups with amino-group-terminated PPTA. The structure of these copolymers was identified by IR spectra. Graft and block copolymers contained PBD segments up to 85 wt % and 45 wt %, respectively. Thermomechanical analyses (TMA) proved the existence of distinctive primary absorption peak corresponding with Tg of PBD for both graft and block copolymers. The Tg's of both types of the copolymers were further ascertained by the DSC curves. TMA curves suggested that the microphase separation occurred between PPTA and PBD. The incorporation of PPTA segments into PBD increased the decomposition temperature compared with the blend polymer composed of PPTA and PBD with the same composition. 相似文献
12.
Masaaki Suzuki Yoshihisa Hasegawa Masayuki Aizawa Yoshinori Nakata Takeshi Okutani Kohei Uosaki 《Journal of the American Ceramic Society》1995,78(1):83-89
The structure of silicon carbide–silicon nitride (SiC–Si3 N4 ) composite particles synthesized using a CO2 laser was studied by magic angle spinning nuclear magnetic resonance (MAS-NMR) and electron spin resonance (ESR). The structure around Si atoms changed by introducing N. C atoms around Si were substituted by N atoms, and N-rich configurations around Si atoms increased stepwise as the N content increased. The low N content composite particles consisted of mainly SiC phase containing dissolved N. N atoms were partly present in β-SiC microcrystal and partly in the grain boundary layer in the particle. N atoms were tetrahedrally surrounded by four Si atoms in β-SiC microcrystal and were trivalent state bonded to three Si atoms in the grain boundary layer. The high N content particles consisted of SiC, Si3 N4 , and amorphous phases, whose amount depended on N content. 相似文献
13.
Poly(p-phenylene terephthalamide) (PPTA) was blended with poly(vinyl chloride) (PVC) by solution-blending method. PPTA was metalated for dissolving in dimethyl sulfoxide. Dimethyl sulfoxide was used as a common solvent. In PPTA/PVC composite, PPTA accelerated the thermal degradation of PVC. PPTA molecules are aggregated as microfibrillar form in PVC matrix. Such microfibrils are dispersed homogeneously in PVC matrix, according to polarizing microscopic observation. The average diameter of the microfibrils becomes smaller in the composite with lower content of PPTA. In the surface region of PPTA microfibrils the intermolecular hydrogen bonds between C? Cl of PVC and N? H of PPTA are formed. Young's modulus and the yield stress at room temperature were higher in the composites than those in PVC. The modulus of the composites was higher, especially at the high temperatures above their glass transition temperatures, than that in PVC. The temperature dependence of modulus can be calculated by using the mechanical model equivalent to the quasi-3-dimensional microfibrillar model which will be approximately applied to the composite structure. It becomes apparent that the modulus of the PPTA microfibrils evaluated by using the mechanical model is higher in the higher molecular weight PPTA. 相似文献
14.
Surface‐modified polypropylene (PP) films with thermally and photochemically sensitive copolymers consisting of N‐(2‐hydroxypropyl)methacrylamide (HPMA) and 4‐(4‐methoxyphenylazo)phenyl methacrylate (MPAP), poly(HPMA‐co‐MPAP)‐g‐PP (abbreviated g‐PP) film, were prepared by graft copolymerization with an Ar‐plasma postpolymerization technique. The surfaces of the g‐PP films were characterized by means of X‐ray photoelectron spectroscopy; the percentage grafting of poly(HPMA‐co‐MPAP) with a number‐average molecular weight of 3.28 × 104 was 7.12%, and the molar ratio of HPMA–MPAH in the copolymer was 0.75:0.25. The stimuli‐sensitive adsorption of albumin and polystyrene microspheres on the g‐PP film was also measured. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 143–148, 2003 相似文献
15.
Yoshiyuki Sakamoto Tomoyoshi Motohiro Shinichi Matsunaga Kohei Okumura Tomoyuki Kayama Kiyoshi Yamazaki Toshiyuki Tanaka Yoshimi Kizaki Naoki Takahashi Hirofumi Shinjoh 《Catalysis Today》2007,121(3-4):217-225
The release and reduction of NOx in a NOx storage-reduction (NSR) catalyst were studied with a transient reaction analysis in the millisecond range, which was made possible by the combination of pulsed injection of gases and time resolved time-of-flight mass spectrometry. After an O2 pulse and a subsequent NO pulse were injected into a pellet of the Pt/Ba/Al2O3 catalyst, the time profiles of several gas products, NO, N2, NH3 and H2O, were obtained as a result of the release and reduction of NOx caused by H2 injection. Comparing the time profiles in another analysis, which were obtained using a model catalyst consisting of a flat 5 nmPt/Ba(NO3)2/cordierite plate, the release and reduction of NOx on Pt/Ba/Al2O3 catalyst that stored NOx took the following two steps; in the first step NO molecules were released from Ba and in the second step the released NO was reduced into N2 by H2 pulse injection. When this H2 pulse was injected in a large amount, NO was reduced to NH3 instead of N2.
A only small amount of H2O was detected because of the strong affinity for alumina support. We can analyze the NOx regeneration process to separate two steps of the NOx release and reduction by a detailed analysis of the time profiles using a two-step reaction model. From the result of the analysis, it is found that the rate constant for NOx release increased as temperature increase. 相似文献
16.
17.
Yasuhiro Jimbo Yuki Tamatsukuri Minato Ito Kohei Yokoyama Yoshiharu Hirakata Shunpei Yamazaki 《Journal of the Society for Information Display》2015,23(7):313-318
To improve the reliability and mechanical durability of a flexible organic light‐emitting diode display, the entire flexible display is coated with an aluminum oxide film by atomic layer deposition (ALD). Because the step coverage of ALD is excellent, the AlOx film was deposited not only on the front and back surfaces but also on the side surfaces of the display. A high‐temperature and high‐humidity preservation test, repetitive bending tests, and a pencil hardness test were conducted on the flexible display with ALD‐AlOx coating. The display survived 500 h of a 65°C, 95% preservation test, endured a 100,000‐time repetitive bending test with a curvature radius of 4 mm, and was found to have a pencil hardness of 4H. 相似文献
18.
Artificial Life and Robotics - We propose a class of generalized multiplicative stochastic processes obtained by introducing an endo-perspective into one-dimensional maps with additive noise. We... 相似文献
19.
Yuichiro Ezoe Ikuyuki Mitsuishi Utako Takagi Masaki Koshiishi Kazuhisa Mitsuda Noriko Y. Yamasaki Takaya Ohashi Fumiki Kato Susumu Sugiyama Raul E. Riveros Hitomi Yamaguchi Shinya Fujihira Yoshiaki Kanamori Kohei Morishita Kazuo Nakajima Ryutaro Maeda 《Microsystem Technologies》2010,16(8-9):1633-1641
We are developing novel ultra light-weight and high-resolution X-ray micro pore optics for space X-ray telescopes. In our method, curvilinear micro pore structures are firstly fabricated by silicon deep reactive ion etching (DRIE) or X-ray LIGA processes. Secondly, side walls of the micro structures are smoothed by magnetic field assisted finishing and/or hydrogen annealing techniques for high reflectivity mirrors. Thirdly, to focus parallel X-ray lights from astronomical objects, these structures are elastically or plastically bent into a spherical shape. Fourthly, the bent structures are stacked to form a multi-stage X-ray telescope. In this paper, we report on fabrication and X-ray reflection tests of silicon and nickel X-ray mirrors using the DRIE and LIGA processes, respectively. For the first time, X-ray reflections were confirmed on both of the mirrors. Estimated rms roughnesses were 5 nm and 3 nm for the silicon and nickel mirrors, respectively. 相似文献
20.
Levesque MJ Ichikawa K Date S Haga JH 《Computer methods and programs in biomedicine》2009,93(1):73-82
Grid computing offers the powerful alternative of sharing resources on a worldwide scale, across different institutions to run computationally intensive, scientific applications without the need for a centralized supercomputer. Much effort has been put into development of software that deploys legacy applications on a grid-based infrastructure and efficiently uses available resources. One field that can benefit greatly from the use of grid resources is that of drug discovery since molecular docking simulations are an integral part of the discovery process. In this paper, we present a scalable, reusable platform to choreograph large virtual screening experiments over a computational grid using the molecular docking simulation software DOCK. Software components are applied on multiple levels to create automated workflows consisting of input data delivery, job scheduling, status query, and collection of output to be displayed in a manageable fashion for further analysis. This was achieved using Opal OP to wrap the DOCK application as a grid service and PERL for data manipulation purposes, alleviating the requirement for extensive knowledge of grid infrastructure. With the platform in place, a screening of the ZINC 2,066,906 compound "drug-like" subset database against an enzyme's catalytic site was successfully performed using the MPI version of DOCK 5.4 on the PRAGMA grid testbed. The screening required 11.56 days laboratory time and utilized 200 processors over 7 clusters. 相似文献