全文获取类型
收费全文 | 830篇 |
免费 | 33篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 63篇 |
化学工业 | 227篇 |
金属工艺 | 19篇 |
机械仪表 | 20篇 |
建筑科学 | 23篇 |
能源动力 | 68篇 |
轻工业 | 77篇 |
无线电 | 57篇 |
一般工业技术 | 137篇 |
冶金工业 | 26篇 |
原子能技术 | 48篇 |
自动化技术 | 99篇 |
出版年
2024年 | 3篇 |
2023年 | 11篇 |
2022年 | 8篇 |
2021年 | 30篇 |
2020年 | 19篇 |
2019年 | 15篇 |
2018年 | 21篇 |
2017年 | 19篇 |
2016年 | 22篇 |
2015年 | 21篇 |
2014年 | 29篇 |
2013年 | 62篇 |
2012年 | 48篇 |
2011年 | 87篇 |
2010年 | 58篇 |
2009年 | 47篇 |
2008年 | 40篇 |
2007年 | 47篇 |
2006年 | 36篇 |
2005年 | 33篇 |
2004年 | 22篇 |
2003年 | 19篇 |
2002年 | 26篇 |
2001年 | 8篇 |
2000年 | 8篇 |
1999年 | 13篇 |
1998年 | 15篇 |
1997年 | 11篇 |
1996年 | 6篇 |
1995年 | 11篇 |
1994年 | 5篇 |
1993年 | 9篇 |
1992年 | 2篇 |
1991年 | 6篇 |
1990年 | 5篇 |
1989年 | 5篇 |
1986年 | 3篇 |
1985年 | 2篇 |
1984年 | 3篇 |
1983年 | 4篇 |
1982年 | 3篇 |
1980年 | 5篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1976年 | 4篇 |
1975年 | 1篇 |
1974年 | 2篇 |
1972年 | 1篇 |
1969年 | 1篇 |
1967年 | 1篇 |
排序方式: 共有864条查询结果,搜索用时 62 毫秒
61.
Tomoyuki Kakigi Nozomi Miyoshi Kazuki Fujii Tatsuya Urakawa Akio Matsuura Takaharu Miura Masakazu Washio 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2007,265(1):118-124
Poly (tetrafluoroethylene-co-perfluoroalkylvinylether) (PFA) was irradiated by soft electron beam (soft-EB) under nitrogen gas atmosphere in solid-state and its molten state, respectively. The changes of thermal property and chemical structures of irradiated PFA in solid-state and molten state were studied by differential scanning calorimetric analysis (DSC) and solid-state 19F magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy. By DSC analysis, the melting temperature shifted to lower temperatures, and crystallinity decreased with increasing soft-EB dose. By solid-state 19F MAS NMR spectroscopy, the new signals was observed and the detected new signals in irradiated PFA at 315 °C and at 30 °C were due to the tertiary carbon group with branching site (Y-type crosslinking site), perfluoro-propylene site and chain end methylene groups, respectively.Moreover, the molar ratio of perfluoroalkylvinylether (FAVE) structure to -CF2- units decreased with increasing dose. 相似文献
62.
Shinkichi Inagaki Tsukasa Egami Tatsuya Suzuki Hisahide Nakamura Koichi Ito 《Electrical Engineering in Japan》2011,174(2):18-25
This paper presents a new nonintrusive appliance load monitoring technique based on integer programming. Nonintrusive appliance load monitoring is the problem of identifying the operating conditions of electric appliances in a house by observing only the overall load current and voltage. Since the overall load current is expressed as a superposition of the currents of the operating appliances, the monitoring problem can be formulated as an integer quadratic programming problem by expressing the operating conditions as integer variables. This problem is solvable with a sufficiently small computational burden thanks to the recent development of commercial software. The proposed method does not require relearning even when a new appliance is installed in the house. Furthermore, the proposed formulation is applicable to cases in which some appliance has multiple modes, and cases in which some appliances of the same type are operating simultaneously. The usefulness of the proposed technique is verified by experimental results. © 2010 Wiley Periodicals, Inc. Electr Eng Jpn, 174(2): 18–25, 2011; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21040 相似文献
63.
64.
Yoshimasa Kondo Takao Saito Tatsuya Terazawa Naoto Ohtake 《Electrical Engineering in Japan》2007,159(4):1-7
Diamondlike carbon (DLC) films show high hardness, high electric resistivity, and the self‐lubricant characteristic, and many applications and synthesis methods have been reported. Pulse plasma chemical vapor deposition (CVD) is one of the synthesis methods suitable for DLC films on complicated form work, such as molding and extruding die. Ordinary, microsecond‐order pulse is used in this method. This paper describes the development of the synthesis method using nanosecond‐order pulse plasma CVD for DLC films. To realize this process, a static induction (SI) thyristor with an inductive energy storage (IES) circuit was used. Compared with microsecond, nanosecond‐order pulse plasma CVD method shows the characteristics of high electron temperature and exponential relationship between pulse frequency and growth rate. The characteristics of the thus‐obtained DLC films show two broad peaks of the disordered band at 1360 cm?1 and the graphitic band at 1580 cm?1 by Raman spectroscopy and hardness of 16.0 GPa and elastic modulus of 170 GPa. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 159(4): 1–7, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20341 相似文献
65.
Numerical Evaluation of Toughening by Crack-Face Grain Interlocking in Self-Reinforced Ceramics 总被引:1,自引:0,他引:1
Serguei Kovalev Tatsuya Miyajima Yukihiko Yamauchi Mototsugu Sakai 《Journal of the American Ceramic Society》2000,83(4):817-824
Crack bridging associated with the pull-out process of interlocking grains in self-reinforced ceramic materials is studied through a micromechanical simulation. The pullout of a single inclined grain is modeled via the numerical solution of a general contact problem. The bridging-force versus crack-opening-distance curve indicates a nonlinear, springlike response for the pullout of interlocking grains. The sliding friction along the debonded interface, induced by highly localized contact stresses, dominates the total bridging force. The bridging force increases with grain inclination until eventual bridge failure. The pullout of misaligned grains mainly affects short-crack toughening, with a rising R -curve, whereas aligned grains contribute to long-crack toughening. The residual stresses of the thermal expansion anisotropy play a minor role in the pull-out process of grain interlocking and the resultant toughening. The proposed mechanism is operative in both single-phase and composite ceramics in which pullout of elongated grains/reinforcements occurs. 相似文献
66.
Min‐Jung Bae Takeshi Ishii Kanako Minoda Yukiko Kawada Tatsuya Ichikawa Taiki Mori Miya Kamihira Tsutomu Nakayama 《Molecular nutrition & food research》2009,53(6):709-715
(–)‐Epigallocatechin gallate (EGCg) is the major component of green tea and is known to show strong biological activity, although it can be easily oxidized under physiological conditions. In this study, we indicate that EGCg is stable in human serum and that human serum albumin (HSA) stabilizes EGCg under aerobic condition. Although EGCg is usually decomposed within 1 h in aqueous solution at neutral pH, EGCg in serum and phosphate buffer (pH 7.4) containing HSA was stable over 1 h, even at neutral and slightly alkaline pH. Under these conditions, EGCg binds to HSA non‐covalently. The sulfhydryl group acts as an antioxidant for EGCg oxidation. Incubation of EGCg with HSA is accompanied by the oxidation of a free sulfhydryl group in HSA. These results suggest that the antioxidant property and the binding capacity of HSA contribute to the stabilization of EGCg in human serum. 相似文献
67.
Volatiles were extracted from rice plants of various growth stages with solid-phase microextraction (SPME) and analyzed by
gas chromatography-mass spectrometry (GC-MS) to identify attractants that cause invasion of the rice leaf bug Trigonotylus caelestialium (Kirkaldy) into paddy fields. The composition of volatile blends produced by rice plants changed with rice development. In
addition, volatile blend compositions differed between the panicles and the stems and leaves. The relative geranyl acetone
content was high in all plant structures analyzed. In volatiles from whole plants in the fourth-leaf stage and panicles in
the full-ripe stage, the relative content of green leaf volatiles (GLVs) was higher than that found in other rice plant structures.
In contrast, relative terpene levels emitted from whole plants in the panicle-formation stage and by panicles and stems and
leaves in the flowering stage were higher than those of other rice plant structures. However, the type of terpenes found differed
between the panicles and the stems and leaves. Relative levels of β-caryophyllene in whole plants in the panicle-formation
stage and panicles in the flowering stage were much higher than that in stems and leaves in the flowering stage. Our previous
studies demonstrated that the odor from whole plants in the panicle-formation stage and panicles in the flowering stage is
attractive to rice leaf bugs. Here, the attractiveness of β-caryophyllene to adult bugs was investigated in olfactometer assays.
Adult females were attracted to β-caryophyllene at a concentration of 0.001%, which is approximately equivalent to the concentration
produced by flowering rice panicles. However, β-caryophyllene also was present in the odor of whole plants in the fourth-leaf
stage and in stems and leaves in the flowering stage. Furthermore, the amounts of this compound emitted from these structures
were similar. Therefore, we suggest that the relative abundance of this compound in a volatile blend is important for attractance
of the bugs. 相似文献
68.
A solid-particle erosive wear test by impinging silicon carbide (SiC) powders was carried out at room temperature over a range
of median particle sizes of 425–600 μm, speed of 100 m/s and impact angle of 90° and assessed by wear measurements and scanning
electron microscopy. Erosive wear behaviour was examined on newly fabricated nano-powder infiltration and transient eutectoid
(NITE) SiC/SiC composites and two commercial composites by the chemical vapour infiltration (CVI) and NITE fabrication route.
Microstructural observation was performed to examine the correlation between erosive wear behaviours and fabrication impurities.
Conspicuous defects were observed in the prototype materials as the forms of porosity, fibre deformation, residual oxide,
pyrolytic carbon (PyC) deformation, PyC cleavage, among others. Erosive wear behaviour was rather serious in the prototype
of fabricated composites, which employ pre-SiC fibre and phenolic resin. Two dominant erosive wear mechanisms were observed:
delamination of constituents, mainly caused by erosive crack propagation, and fragmentation and detachment of constituents,
which usually resulted from erosive impact. A unit size of delamination was the most decisive factor affecting wear volume.
The bonding strength of each constituent was mostly affected by various forms of porosities. Therefore, the fundamental cause
and subsequent results must be carefully elucidated. The correlation of microstructural defect and wear behaviour was investigated
with the aim of reducing dominant wear by improving fabrication conditions. The final product of the cost-effective composite
had a 2.5-fold higher resistance than the commercial CVI composite. Consequently, by controlling fabrication impurities, we
have been successful in developing and improving a new fabrication technique; consequently, the known defects are rarely observed
in final product. A schematic wear model of erosive wear mechanisms is proposed for the newly fabricated SiC/SiC composites
under particle erosion. 相似文献
69.
Hiroshi Kanbe Mami Hirose Tatsuya Ito Masafumi Taniwaki 《Journal of Electronic Materials》2010,39(8):1248-1255
Ge/Si heterojunctions formed by wet wafer bonding were observed using transmission electron microscopy and energy-dispersive
x-ray spectroscopy. For the samples annealed at 880°C, there was a transition layer at the heterointerface with modified regions
in the Si and Ge extending 20 nm to 30 nm from the interface. In these modified regions, crystal defects were observed, and
a large amount of Ge was detected on the Si side of the junction. For the samples annealed at 250°C or 350°C, the transition
layers had an amorphous-like structure with a thickness of about 10 nm. No modified layer or enlargement of lattice spacing
was observed. 相似文献
70.
Harumi Yokokawa Natsuko Sakai Tatsuya Kawada Masayuki Dokiy 《Journal of the American Ceramic Society》1990,73(3):649-658
The thermodynamic properties of double oxides in rare earth-transition metal (V and Mn)-oxygen ternary systems have been collected and evaluated to examine their stability using chemical potential diagrams plotted as log (αA /αB ) vs log ( P (O2 )). The thermodynamic regularities of perovskites, pyrochlores, and other compounds have been discussed in terms of the effective ionic radii across a series of rare earths. The obtained regularities have been used to estimate tentatively the thermodynamic properties of some rare-earth vanadium and manganese oxides. 相似文献