全文获取类型
收费全文 | 1745篇 |
免费 | 78篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 75篇 |
综合类 | 3篇 |
化学工业 | 364篇 |
金属工艺 | 44篇 |
机械仪表 | 54篇 |
建筑科学 | 19篇 |
能源动力 | 40篇 |
轻工业 | 146篇 |
水利工程 | 2篇 |
无线电 | 268篇 |
一般工业技术 | 355篇 |
冶金工业 | 322篇 |
原子能技术 | 40篇 |
自动化技术 | 95篇 |
出版年
2023年 | 10篇 |
2022年 | 15篇 |
2021年 | 22篇 |
2020年 | 16篇 |
2019年 | 18篇 |
2018年 | 34篇 |
2017年 | 26篇 |
2016年 | 40篇 |
2015年 | 29篇 |
2014年 | 49篇 |
2013年 | 88篇 |
2012年 | 58篇 |
2011年 | 74篇 |
2010年 | 52篇 |
2009年 | 66篇 |
2008年 | 82篇 |
2007年 | 50篇 |
2006年 | 50篇 |
2005年 | 72篇 |
2004年 | 36篇 |
2003年 | 41篇 |
2002年 | 55篇 |
2001年 | 37篇 |
2000年 | 32篇 |
1999年 | 41篇 |
1998年 | 134篇 |
1997年 | 89篇 |
1996年 | 55篇 |
1995年 | 42篇 |
1994年 | 48篇 |
1993年 | 37篇 |
1992年 | 25篇 |
1991年 | 24篇 |
1990年 | 28篇 |
1989年 | 16篇 |
1988年 | 22篇 |
1987年 | 15篇 |
1986年 | 18篇 |
1985年 | 24篇 |
1984年 | 17篇 |
1983年 | 13篇 |
1982年 | 14篇 |
1981年 | 11篇 |
1980年 | 21篇 |
1979年 | 16篇 |
1978年 | 11篇 |
1977年 | 17篇 |
1976年 | 14篇 |
1973年 | 6篇 |
1970年 | 3篇 |
排序方式: 共有1827条查询结果,搜索用时 15 毫秒
41.
Takashi Yamashiki Toshihiko Matsui Keisuke Kowsaka Masayoshi Saitoh Kunihiko Okajima Kenji Kamide 《应用聚合物科学杂志》1992,44(4):691-698
A novel cellulose solution, prepared by dissolving an alkali-soluble cellulose, which was obtained by the steam explosion treatment on almost pure natural cellulose (soft wood pulp), into the aqueous sodium hydroxide solution with specific concentration (9.1 wt %) was employed for the first time to prepare a new class of multifilament-type cellulose fiber. For this purpose a wet spinning system with acid coagulation bath was applied. The mechanical properties and structural characteristics of the resulting cellulose fibers were compared with those of regenerated cellulose fibers such as viscose rayon and cuprammonium rayon commercially available. X-ray analysis shows that the new cellulose fiber is crystallographically cellulose II, and its crystallinity is higher but its crystalline orientation is slightly lower than those of other commercial regenerated fibers. The degree of breakdown of intramolecular hydrogen bond at C3[Xam(C3)] of the cellulose fiber, as determined by solid-state cross-polarization magic-angle sample spinning (CP/MAS) 13C NMR, is much lower than other, and the NMR spectra of its dry and wet state were significantly different from each other, indicating that cellulose molecules in the new cellulose fiber are quite mobile when wet. This phenomenon has not been reported for so-called regenerated cellulose fibers. 相似文献
42.
Masayoshi Ohashi Shoji Kawakami Yoshiyuki Yokogawa Gao-Chao Lai 《Journal of the American Ceramic Society》2005,88(9):2615-2618
It is necessary for encapsulants to have not only a suitable coefficient of thermal expansion (CTE) compatible to IC devices and a low dielectric constant to reduce the device propagation delay, but also a high thermal conductivity to dissipate large amounts of heat from power-hungry, high-speed IC and high-density packages. Fillers such as silica have been mixed with polymers to improve their properties. Aluminum nitride (AlN) is considered as an alternative one, because it has a higher theoretical thermal conductivity of ∼320 W/mK1 , a compatible CTE with silicon chips and a low dielectric constant. Commercial AlN fillers are angular in shape, because they are prepared via grinding coarse AlN powders synthesized by direct nitridation of aluminum metal and classification. The angular AlN are not expected to have high fluidity when mixed with polymers and hence low packing density. Recently, we successfully obtained single-crystalline spherical AlN fillers. Furthermore, polymer composites filled with the spherical AlN showed excellent thermal conductivity (>8 W/mK) as encapsulants for dissipating the heat generated in electronic devices. 相似文献
43.
Chengzhou Li Yusuke Imai Yoshio Adachi Hiroshi Yamada Keiko Nishikubo Chao-Nan Xu 《Journal of the American Ceramic Society》2007,90(7):2273-2275
An organic aqueous solution of metal acetylacetonate precursors was subjected to spray pyrolysis in order to fabricate SrAl2 O4 :Eu (SAO) nanoparticles. Non-agglomerated luminescent SAO nanoparticles, having a spherical shape with a size of 10–30 nm, were achieved in a single step, while only submicrometer-sized SAO particles were obtained from the conventional ultrasonic pyrolysis of the metal nitrates. Without any post-annealing process, the as-prepared SAO nanoparticles were observed to exhibit a strong photoluminescence, which is comparable with that of the submicrometer-sized SAO particles. A mechanism for the formation of the nanoparticles is also discussed. 相似文献
44.
Lingyun Lyu Takeshi Hanada Naohiro Yamahira Jun Morita Ryota Yamamoto Ken Itomi Takumi Adachi Sho Kubouchi Shin Horiuchi 《应用聚合物科学杂志》2021,138(45):51443
The distribution of nano-sized silica in binary rubber blends is characterized by scanning transmission electron microscopy (STEM) tomography combined with energy dispersive X-ray spectrometry (EDX). 3D distribution of silica is visualized by STEM-EDX tomography with the tilt-series of silicon elemental maps, while the phase-separated morphologies of polyisoprene rubber (IR) and styrene-butadiene rubber (SBR) are visualized by STEM-tomography in high-angle-annular-dark field (HAADF) mode. The combination of STEM-EDX and STEM-HAADF tomography enables us to determine the distribution of silica between the two rubber phases quantitatively even with high contents of silica up to 70 phr (weight parts per hundred rubber). It is found that silica is preferentially distributed in the SBR phase, but it is also distributed in the IR phase when the IR fraction in the total rubber components is higher than 40 wt%. The preferential distribution of silica in the SBR phase improves the dispersion of the IR domains. This is the first use of this technique for a multicomponent polymer system, showing the advantage to characterize the complicated multicomponent polymer composite morphologies. 相似文献
45.
A 17Ni–0.2C martensite steel was rapidly heated below the austenite formation temperature and deformed in compression. Continuous dynamic recrystallization was observed. The behavior is similar to that in a ferrite–pearlite steel but the onset strain is much smaller. Sub-micron ferrite grains were obtained through the dynamic recrystallization. 相似文献
46.
Kayo Suzuki Author Vitae Author Vitae Hiroaki Ikeda Author Vitae Author Vitae Fumio Adachi Author Vitae 《Computers & Electrical Engineering》2008,34(1):21-37
This paper focuses on a practical design for an efficient scalable image database and retrieval system over broadband networks. It describes a concrete solution for the implementation of HD/SHD (high-definition/super-high-definition) still image retrieval services which can be used in different applications. The structure of the complete system, consisting of a directory server, an image server, and MMI (man-machine interface) devices, has been presented, detailing each element and their corresponding functions. The desired HD/SHD image is displayed on the HD-PDP (plasma display panel) with the aid of image matching. The proposed system generates image index automatically, eliminating special skills in preparing index images and crucially reducing the processing time (from 35 min to 110 s), and does not use keywords. It has been also shown that these indices can be used for quite accurate image retrieval, i.e., the system provides high precision rates (currently up to 98%) to the user, eliminating troubles encountered in the image retrieval operations due to limitation on the user’s age, culture, knowledge, and languages.The broadband IP networks currently have a number of issues from the viewpoint of practical system operations, and so the requirements and issues needed for the networks are discussed from the viewpoint of in-service performance, differentiation among different types of services, secure connections, and so on, focusing on handling of HD/SHD still images. 相似文献
47.
Hideaki Adachi Toshifumi Satoh Masahiro Sakai Koichi Mizuno Kentaro Setsune 《Journal of Superconductivity》1994,7(4):737-741
Epitaxial multilayer thin films of infinite-layer (Sr, Ca)CuO2 and perovskite (Sr, Ca)RuO3 have been prepared on (100) SrTiO3 substrates by multitarget rf magnetron sputtering. X-ray diffraction analyses revealed that the multilayer structure of (Sr, Ca)CuO3/(Sr, Ca)RuO3 was successfully fabricated with a minimum layer thickness of 20 Å. Transmission electron microscopy measurements of the multilayers indicated that there was no dislocation which normally exists in single-layer films with an infinite-layer structure. Resistivities of multilayer films at room temperature ranged from 1 to 10 m cm and showed semiconductor-like dependence against the temperature. 相似文献
48.
An imaging method was developed based on null ellipsometry with a white-light source. It is useful for visualizing the kinetics of fast surface phenomena on the nanometer scale. 相似文献
49.
Xia Cao Wang Dong F. Ono Takahito Itoh Toshihiro Esashi Masayoshi 《Microsystem Technologies》2022,28(11):2443-2453
Microsystem Technologies - In this paper, a system of magnetically coupled oscillators consisting of a Π-shaped horizontal cantilever and a rectangular vertical cantilever with a frequency... 相似文献
50.
Solution‐Processed Organic–Inorganic Perovskite Field‐Effect Transistors with High Hole Mobilities
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)