全文获取类型
收费全文 | 614篇 |
免费 | 5篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 17篇 |
综合类 | 1篇 |
化学工业 | 118篇 |
金属工艺 | 5篇 |
机械仪表 | 14篇 |
建筑科学 | 11篇 |
矿业工程 | 1篇 |
能源动力 | 17篇 |
轻工业 | 51篇 |
水利工程 | 1篇 |
无线电 | 75篇 |
一般工业技术 | 70篇 |
冶金工业 | 198篇 |
原子能技术 | 12篇 |
自动化技术 | 29篇 |
出版年
2022年 | 3篇 |
2021年 | 15篇 |
2020年 | 4篇 |
2019年 | 2篇 |
2018年 | 6篇 |
2017年 | 2篇 |
2016年 | 7篇 |
2015年 | 5篇 |
2014年 | 11篇 |
2013年 | 17篇 |
2012年 | 19篇 |
2011年 | 22篇 |
2010年 | 17篇 |
2009年 | 12篇 |
2008年 | 21篇 |
2007年 | 25篇 |
2006年 | 13篇 |
2005年 | 23篇 |
2004年 | 14篇 |
2003年 | 13篇 |
2002年 | 11篇 |
2001年 | 6篇 |
2000年 | 19篇 |
1999年 | 13篇 |
1998年 | 73篇 |
1997年 | 50篇 |
1996年 | 24篇 |
1995年 | 25篇 |
1994年 | 21篇 |
1993年 | 22篇 |
1992年 | 3篇 |
1991年 | 9篇 |
1990年 | 8篇 |
1989年 | 9篇 |
1988年 | 4篇 |
1987年 | 8篇 |
1986年 | 7篇 |
1985年 | 13篇 |
1984年 | 3篇 |
1983年 | 5篇 |
1982年 | 4篇 |
1981年 | 6篇 |
1980年 | 3篇 |
1979年 | 5篇 |
1978年 | 3篇 |
1977年 | 2篇 |
1976年 | 6篇 |
1973年 | 3篇 |
1972年 | 2篇 |
1959年 | 1篇 |
排序方式: 共有620条查询结果,搜索用时 15 毫秒
21.
A key mechanism of the current-induced magnetization dynamics is the spin torque from a spin polarized current (spin current), which couples to spatial gradient of magnetization. Recently, it was pointed out that a large spin current applied to a uniform ferromagnet leads to a spin-wave instability. In this paper, we show that such instability is absent in a state containing a domain wall. This may indicate that nucleation of magnetic domains occurs above a certain critical spin current. This scenario is supported by an explicit energy comparison between the uniformly magnetized state and the domain-wall state under spin current. 相似文献
22.
Koji Honda Ikuo Yamamoto Masamichi Morita Hiroki Yamaguchi Hiroshi Arita Ryohei Ishige Yuji Higaki Atsushi Takahara 《Polymer》2014
The effect of α-substituent on the molecular motion and wetting behavior of poly{2-(perfluorobutyl)ethyl acrylate} [PFA-C4], poly{2-(perfluorobutyl)ethyl methacrylate} [PFMA-C4], poly{2-(perfluorobutyl)ethyl α-fluoroacrylate} [PFFA-C4], and poly{2-(perfluorobutyl)ethyl α-chloroacrylate} [PFClA-C4] films were characterized by dynamic contact angle measurement, lateral force microscopy (LFM), wide angle X-ray diffraction (WAXD), and X-ray photoelectron spectroscopy (XPS). WAXD of oriented PFClA-C4 fiber suggested the presence of rod-like chain due to the presence of bulky α-substituent. The glass transition temperature (Tg) of PFFA-C4 and PFClA-C4 were well above the room temperature. The water repellencies of PFFA-C4 and PFClA-C4 were as high as that of PFMA-C4 and their oil repellency of PFFA-C4 and PFClA-C4 was higher than the PFMA-C4. This result was originated from the low main chain mobility of PFFA-C4 and PFClA-C4 due to the presence of bulky α-substituents. The effect of molecular motion on water repellency was clarified by the results of temperature dependence studies of dynamic contact angle, LFM, and surface chemical composition measured by XPS. 相似文献
23.
Guanghui Cui Masamichi Fujikawa Shusaku Nagano Masami Sano Hiroshi Takase Tsukasa Miyazaki Shinichi Sakurai Katsuhiro Yamamoto 《Polymer》2014
Polystyrene-b-poly(methyl acrylate) (PS-b-PMA) block copolymer with PS volume fraction of 25.2 vol% was synthesized by atom transfer radical polymerization. Non-pretreated silicon wafers were used as the substrates to prepare perpendicular oriented PS cylinders in PMA matrix via solvent annealing which could induce the transformation of spheres to vertically oriented and hexagonally packed cylinders. The spherical microdomains were formed after the evaporation of solvents from the solutions of the block copolymer in selective solvents mixed from methanol, acetone and dichloromethane. The thickness of films could be as thick as 1000 nm, which were much thicker than usual cases and the cylinders came from the directional coalescence of the spheres, thus any pre-treatments of the substrates were not required for perpendicular orientation. The structures were characterized by small angle X-ray scattering (SAXS), transmission electron microscope (TEM), atom force microscopy (AFM) and grazing incidence small angle X-ray scattering (GISAXS). 相似文献
24.
25.
Huan-Bang Li Takashi Takahashi Masahiro Toyoda Yasuyuki Mori Ryuji Kohno 《Wireless Personal Communications》2009,51(4):697-709
Wireless Body Area Network (WBAN) is expected to play an important role in supporting medical and healthcare services with
increased convenience and comfort. One main advantage of WBAN is that it enables automatic biosignal collection in real time
which is essential in medical treatment and healthcare vigilance. To harmonize with the strong demands from both medical and
healthcare societies, and information and communications technology industries, IEEE 802 Standard Committee set up a task
group of TG15.6 to develop an IEEE wireless standard on WBAN. In this paper, we first review the main activities of TG15.6
with the updated status. Then, we present a prototype WBAN system that is implemented by using ultra-wideband technology.
Multi-hop mechanism is adopted to guarantee reliable connection. Finally, we describe an experimental system that uses the
developed WBAN system by combining with satellite communication in supporting remote medical treatment and healthcare. In
case of less of medical resources such as in emergency, in rural or isolated areas, such a system is important in sending
the corresponding biosignal to a remote hospital in real time to help patient management. The relative delay of WBAN data
delivery via satellite is measured which is dependent on the satellite link capacity. 相似文献
26.
Hiroshi Kominami Masaaki Kohno Yukino Matsunaga Yoshiya Kera 《Journal of the American Ceramic Society》2001,84(5):1178-1180
Silica-modified titanium oxide (S-TiO2 ) powders that have an anatase structure were synthesized via the thermal decomposition of mixtures of titanium(IV) isopropoxide (TIP) and tetramethyl orthosilicate (TMOS) in toluene at 300°C. These S-TiO2 materials had high rutile-transformation temperatures and maintained large surface areas at elevated temperatures (550°–1000°C). For example, the product that was prepared from a 9:1 TIP:TMOS mixture transformed to rutile at ∼1100°C and possessed a surface area of 160 m2 /g, even after calcination at 800°C for 1 h. 相似文献
27.
28.
Proposes a method for designing spread sequences for a spread spectrum (SS) communication and ranging system. The proposed sequence is composed by concatenated equivalently odd and even (EOE) inner-sequences and an M outer sequence. We have previously proposed EOE sequences that have equivalently good properties of both even and odd correlation, what are important features for acquisition and demodulation in SS communications. Usually, simple concatenation of pseudonoise-sequences results in sequences with bad autocorrelation properties. Unlike the latter, concatenation of EOE inner sequences result in sequences with good correlation properties, exhibiting low sidelobe peaks, what is useful for achieving stable acquisition. The proposed sequences have long period. Therefore, the single concatenated EOE sequence is suitable for a spread spectrum system with both communication and ranging functions 相似文献
29.
Chun Li Naoe Isshiki Hiromu Saito Kazufumi Kohno Akinori Toyota 《Polymer Bulletin》2009,63(6):779-788
We investigated the formation of inclusion complexes (ICs) between cyclodextrins (CDs) with different cavity size and polyolefin
(PO) with different side chains by using Fourier transform infrared (FTIR) spectroscopy, wide-angle X-ray diffraction (WAXD)
and differential scanning calorimetry. The analysis of FTIR spectra revealed that the resultants were complexes of CD and
PO, and the analysis of WAXD revealed that the molecules of CD had a channel structure due to the formation of ICs. We found
that IC could not be obtained when the cavity size of CD was small for PO molecules to thread and it was too large for cross-sectional
area of PO molecules. Thus, it was found that PO1 with few side chains could form IC with α-CD, and PO2 with ethyl side chain
could form IC with β-CD and γ-CD, while the PO3 with 2-methyl-propyl side chain could form IC with γ-CD. These results suggest
that the cross-sectional areas of polymer and the cavity size of CDs play critical roles in the formation of ICs. It is only
possible to form ICs when the polymer chains can tread into cavities of CDs, and the space between the polymer and CD is suitable
to provide enough intermolecular interaction to keep the structure of IC stable. 相似文献
30.
Recent computational studies (Phys. Rev. Lett. 70 (1993) 1960; Phys. Rev. B 62 (2000) 17055) predicted that friction of ordered organic monolayer had characteristic dependence on temperature, where the maximum friction was observed around rotator transition point of the monolayer. This remained to be confirmed experimentally. Using a friction force microscope (FFM) combined with a temperature regulation module, we attempted to investigate such dependence on temperature (130 K-room temperature) on a self-assembled monolayer of dodecanethiol prepared on Au(1 1 1). The observed friction showed strong dependence on temperature and good agreement with the computational prediction. 相似文献