全文获取类型
收费全文 | 1629篇 |
免费 | 25篇 |
国内免费 | 19篇 |
专业分类
电工技术 | 98篇 |
综合类 | 7篇 |
化学工业 | 586篇 |
金属工艺 | 100篇 |
机械仪表 | 35篇 |
建筑科学 | 28篇 |
矿业工程 | 1篇 |
能源动力 | 75篇 |
轻工业 | 73篇 |
水利工程 | 5篇 |
石油天然气 | 8篇 |
武器工业 | 1篇 |
无线电 | 127篇 |
一般工业技术 | 290篇 |
冶金工业 | 61篇 |
原子能技术 | 44篇 |
自动化技术 | 134篇 |
出版年
2022年 | 13篇 |
2021年 | 14篇 |
2019年 | 14篇 |
2018年 | 11篇 |
2017年 | 12篇 |
2016年 | 20篇 |
2015年 | 12篇 |
2014年 | 22篇 |
2013年 | 82篇 |
2012年 | 49篇 |
2011年 | 54篇 |
2010年 | 57篇 |
2009年 | 72篇 |
2008年 | 71篇 |
2007年 | 62篇 |
2006年 | 53篇 |
2005年 | 62篇 |
2004年 | 46篇 |
2003年 | 57篇 |
2002年 | 56篇 |
2001年 | 52篇 |
2000年 | 36篇 |
1999年 | 38篇 |
1998年 | 56篇 |
1997年 | 50篇 |
1996年 | 37篇 |
1995年 | 34篇 |
1994年 | 39篇 |
1993年 | 37篇 |
1992年 | 21篇 |
1991年 | 40篇 |
1990年 | 20篇 |
1989年 | 27篇 |
1988年 | 22篇 |
1987年 | 33篇 |
1986年 | 29篇 |
1985年 | 15篇 |
1984年 | 25篇 |
1983年 | 27篇 |
1982年 | 22篇 |
1981年 | 23篇 |
1980年 | 17篇 |
1979年 | 22篇 |
1978年 | 10篇 |
1977年 | 17篇 |
1976年 | 14篇 |
1975年 | 11篇 |
1973年 | 13篇 |
1972年 | 8篇 |
1971年 | 8篇 |
排序方式: 共有1673条查询结果,搜索用时 15 毫秒
1.
Kotaro Matsuuchi Tadashi Fukami Nobuyuki Naoe Ryoichi Hanaoka Shinzo Takata Toshio Miyamoto 《Electrical Engineering in Japan》2005,150(2):43-49
This paper presents a method of predicting the steady‐state performance of a new hybrid‐excitation synchronous machine (HESM) theoretically. The field pole of this HESM is axially divided into two parts; one is an excitation part and the other a permanent‐magnet (PM) part. A nonlinear equivalent circuit, which can include the saliency of the rotor and the magnetic saturation due to the iron core, is derived. Based on this equivalent circuit, the steady‐state performance of the HESM is calculated, and the results are confirmed through experiments. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 150(2): 43–49, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20033 相似文献
2.
Kenji Nomura Hiromichi OhtaKazushige Ueda Toshio Kamiya Masahiro HiranoHideo Hosono 《Thin solid films》2003,445(2):322-326
We have investigated the characteristics of transparent metal-insulator-semiconductor field-effect transistors (MISFETs) fabricated using InGaO3(ZnO)m (m=integer) single-crystalline thin films as n-channel layers and amorphous alumina as gate insulator films. The MISFETs exhibit good characteristics such as insensitivity to visible light illumination, off-current as low as ∼1 nA with a positive threshold voltage of ∼3 V and on/off current ratio of 105. The field-effect mobility increased from ∼1 to ∼10 cm2 (V s)−1 as the m-value increased. Room temperature Hall mobility also increased. However, unexpectedly these values were lower than the field-effect mobility. It is explained by existence of shallow localized state in the homologous compounds. 相似文献
3.
Toshio Kimura Hideto Kajiyama Ryuichi Yazaki Takashi Yamaguchi 《Journal of Materials Science》1996,31(15):4149-4157
The densification and microstructure development of ZnO containing Zn7Sb2O12, ZrO2, and aggregated ZnO were investigated to elucidate the effect of nondensifying inclusions on the sintering of ceramic/ceramic composites. The inclusion retarded the densification, and the degree of retardation was found to depend on the chemical species of inclusion; Zn7Sb2O12 had the largest effect, followed by ZrO2 and then aggregated ZnO last. The experimental results for aggregated ZnO was explained by the theory which predicts the generation of backstresses. The backstresses give a less significant effect on the densification. For Zn7Sb2O12 and ZrO2, the microstructure of the matrix varied with distance from an inclusion particle; much porosity was observed in the region surrounding the inclusion. Circumferential voids, which are responsible for the suppression of densification, form during the initial stage of sintering. Inclusion particles generate an anchoring effect which retards the densification of the matrix immediately surrounding the inclusion particle during the intermediate stage.Supported by the Inamori Foundation. 相似文献
4.
Masaaki Miyamoto Hiroyuki Koike Toshio Sada Yasuteru Ijima Junichiro Fukushige Norio Nakamura 《Lipids》1991,26(12):1316-1319
Platelet-activating factor (PAF) is a potent inflammatory mediator which is released by various inflammatory cells and produced
by certain tissues, including the kidney. PAF has been shown to increase glomerular permeability to protein and to decrease
glomerular filtration rate (GFR) by contracting mesangium. On the basis of these observations, it has been suspected that
PAF may play a role as mediator of glomerular damage in glomerular nephritis. To examine this possibility, we studied the
effects of a specific PAF antagonist, R-75,317, on the development of an experimental model of anti-glomerular basement membrane
(anti-GBM) glomerulonephritis. Glomerulonephritis was initiated by injecting rabbit anti-rat GBM serum into rats. Proteinuria
gradually developed after serum injection, plateaued at week 2, and remained at the high level of week 2 throughout the experimental
period (6 wk). Chronic treatment with R-75,317 (10 mg/kg/day i.p.) tended to delay the onset of proteinuria and significantly
accelerated the recovery phase. Creatinine clearance (Ccr) fell to 40% at week 3. R-75,317 treatment completely prevented
this decline of Ccr. Histological changes in this model (glomerular hypertrophy, proliferation of mesangial matrix and interstitial
fibrosis) were also ameliorated by the R-75,317 treatment. The results suggest that PAF may play a role in the development
of glomerulonephritis and that PAF antagonists could be used in the treatment of human renal disease.
Based on a paper presented at the Third International Conference on Platelet-Activating Factor and Structurally Related Alkyl
Ether Lipids, May 1989. 相似文献
5.
SiB4±x
and SiB6 plates were prepared by chemical vapour deposition (CVD) using SiCl4, B2H6 and H2 gases under the conditions of deposition temperatures (T
dep) from 1323–1773 K, total gas pressures (P
tot) from 4–40 kPa and B/Si source gas ratio (m
B/Si=2B2H6/SiCl4) from 0.2–2.8. The effects of CVD conditions on the morphology, structure and composition of the deposits were examined.
High-purity and high-density SiB4±x
and SiB6 plates about 1 mm thick were obtained at the deposition rates of 71 and 47 nm s−1, respectively. The lattice parameter, composition and density of CVD SiB4±x
plates were dependent on their non-stoichiometry. The lattice parameter,a, was 0.6325 nm, butc ranged from 1.262–1.271 nm.The B/Si atomic ratio ranged from 3.1–5.0, and the density ranged from 2.39–2.45×103 kg m−3. The CVD SiB6 plates showed constant values of lattice parameters (a=1.444 nm,b=1.828 nm,c=0.9915 nm), composition (B/Si=6.0) and density (2.42×103 kg m−3), independent of CVD conditions. 相似文献
6.
High performance liquid chromatographic separation of a series of mono-, di- and trihydroxylated 5β-cholanic acids which differ
only in position and configuration of hydroxyl groups at positions C-3, C-7 and/or C-12, is reported. The C-24 free acids
were derivatized to four different classes of UV-sensitive esters, i.e.,p-bromophenacyl (BP),m-methoxyphenacyl (MP), 4-nitrophthalimidemethyl (NPM) and 9-anthrylmethyl (AM) esters, and chromatographed on two, variants
of C18 reversed-phase columns (Nova-Pak C18 and Zorbax ODS) with methanol-water systems as mobile phase. Separation efficiency and elution order of some isomeric pairs
were influenced by both the structure of the C-24 ester groups and the nature of the columns used. Excellent chromatographic
properties were found for those derivatives, particularly for the NPM esters. 相似文献
7.
The esters of dichloropropanols from the byproduct of hydrolysates during food processing were degraded by the cell-free extracts of a dichloropropanol-assimilating bacterium of Pseudomonas sp. OS-K-29. 1-Acyloxy-2,3-dichloropropane was hydrolysed into the corresponding carbonic acid and 2,3-dichloropropanol, and then the dichloropropanol was dechlorinated. The esterase activity of the cell-free extracts was effective for the esters of the dichloropropanols and monoacylglycerides, but not for hydrolysing the lipase substrates such as triacylglycerides and Tween 60. A comparative study using a series of octanoyl glycerides and the esters of the dichlopropanols showed that the substrate specificities of the cell-free extracts were similar to the monoacylglyceride lipase from Penicillium camembertii. 相似文献
8.
A new evacuation method for emergencies, the Follow Me method, in which each leader takes only one evacuee to an exit without gesturing or loudly directing many evacuees toward the exit, was compared, in two field experiments, with a traditional method, the Follow Directions method, in which each leader indicates the direction with a loud voice and vigorous gestures. Results showed that the Follow Me method was more effective when the leader-to-evacuee ratio was relatively small, such as 1:4, and less effective when the ratio was large, such as 1:8. Effective evacuation by the Follow Me method was shown to be caused by the drawing power of emergent small groups. Generating from around a leader, other evacuees rapidly formed a collective stream toward the exit. Small groups can be used as a lever in moving a larger collectivity in an emergency, as well as in activating a large formal organization. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
9.
The fatigue crack propagation rate and the fatigue threshold were investigated for transverse-butt-welded joints of the austenitic stainless steel SUS304. Specimens were of the center-cracked type. In three sets of tests the fatigue crack passed through the weld metal, and in the other two sets, through the base metal. The fatigue crack propagation properties coincided with each other at different stress ratios for the weld metal, and at the higher stress ratios for the base metal. The propagation properties improved at the stress ratio of zero for the base metal. The absence of a stress ratio effect means that the coincided properties are basic ones in which fatigue crack closure does not occur. However, fractographic appearance and surface roughness were quite different between weld metal and base metal. The coincidence of fatigue crack propagation properties in spite of the difference in fractographic features reveals that the fractographic appearance and surface roughness only have a minor effect on basic fatigue crack propagation behaviour. 相似文献
10.
Transaction Oriented Prolog-Online Environment is a multi-user, mainframe implementation of the logic programming language Prolog, specially designed and developed for the data processing environment. This article describes the background, functionality, implementation and use of TOP-ONE, stressing that applications of knowledge-based systems technology to data processing environments will achieve full success only when existing systems and existing conventional data are incorporated within the applications. 相似文献