全文获取类型
收费全文 | 121篇 |
免费 | 0篇 |
专业分类
电工技术 | 5篇 |
化学工业 | 28篇 |
金属工艺 | 8篇 |
能源动力 | 4篇 |
轻工业 | 4篇 |
无线电 | 3篇 |
一般工业技术 | 54篇 |
冶金工业 | 13篇 |
自动化技术 | 2篇 |
出版年
2024年 | 1篇 |
2021年 | 1篇 |
2020年 | 1篇 |
2013年 | 4篇 |
2012年 | 5篇 |
2011年 | 19篇 |
2010年 | 12篇 |
2009年 | 6篇 |
2008年 | 13篇 |
2007年 | 9篇 |
2006年 | 4篇 |
2005年 | 3篇 |
2004年 | 2篇 |
2003年 | 2篇 |
2002年 | 6篇 |
2001年 | 1篇 |
2000年 | 3篇 |
1999年 | 2篇 |
1998年 | 6篇 |
1997年 | 5篇 |
1995年 | 3篇 |
1994年 | 5篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1981年 | 1篇 |
排序方式: 共有121条查询结果,搜索用时 15 毫秒
1.
The glass‐transition temperature as a function of curing conversion for a modified diallylbisphenol A/diaminodiphenylsulfone/bismaleimide (BMI) resin was investigated at different temperature regimes and modeled using a modified Di Benedetto equation. Although the relationship between the glass‐transition temperature and conversion of the BMI system conforms to the Di Benedetto equation for α < 0.6 and at lower cure temperatures, at higher cure temperatures the results deviated significantly from the equation; thus, it was an inadequate model for the system. Fourier transform IR analysis showed that the major crosslinking reactions did not occur during cure for the modified BMI at and below 150°C. However, as the cure temperature was increased, the crosslinking reactions responsible for 3‐dimensional network structures became more dominant. At 190°C the C? N? Cstretch vibration of the uncured maleimide ring converted into succinimide rings in the curing process. Simultaneously, a decrease was observed for the absorbance bands of ? C? Hbending (maleimide). The higher cure temperatures induced a significantly faster initial crosslinking rate and also resulted in a shorter period of time after which further crosslinking was retarded, because the increase in the crosslinks also physically slowed further crosslinking activity. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 227–235, 2002 相似文献
2.
K. A. Khor F. Y. C. Boey Y. Murakoshi T. Sano 《Journal of Thermal Spray Technology》1994,3(2):162-168
There has been increasing use of Al-Li alloys in the aerospace industry, due mainly to the low density and high elastic modulus
of this material. However, the problem of low ductility and fracture toughness of this material has limited its present application
to only weight- and stiffness-critical components. Development of Al-Li/ceramic composites is currently being investigated
to enhance the service capabilities of this material. The Ti-Al alloy is also of interest to aerospace-type applications,
engine components in particular, due to its attractive high-temperature properties. Preparation of fine powders by plasma
melting of composite feedstock and coatings formed by plasma spraying was carried out to examine the effect of spray parameters
on the microstructure and properties of these materials. Characterization of the powders and coatings was performed using
the scanning electron microscope and image analyzer. Examination of the plasma-sprayed powders and coatings has shown that
in the Al-Li/SiC composite there is melting of both materials to form a single composite particle. The SiC reinforcement was
in the submicron range and contributed to additional strengthening of the composite body, which was formed by a cold isostatic
press and consolidated by hot extrusion or hot forging processes. The plasma-sprayed Ti-Al powder showed four categories of
microstructures: featureless, dendritic, cellular, and martensite-like. 相似文献
3.
The paper describes a method of fractionating vegetable, animal and fish oils, and in particular palm oil. The method involves
addition of a medium comprising two common solvents to the semisolid oils. On centrifugation, the olein and stearin are separated
by the medium in the middle. Thirteen media made up from binary combinations of nine solvents, viz. water, propylene glycol,
glycerine, methanol, ethanol,n-propanol, isopropanol (IPA), acetone and butanone, are found to be effective in olein-stearin separation. However, only the
water/IPA and water/methanol systems have been studied in detail. The aqueous IPA provides a higher yield of olein than water/
methanol but intersolubility between oil and medium is also greater. The fractionation process can be carried out at any suitable
temperature. Fractionation of the special prime bleached (SPB) palm oil at 16 C yields an olein with a cloud point of 4.8
C. Some hybrid palm oils produce a large quantity of low cloud point olein which can be bleached readily. The process can
be extended to include degumming and neutralization by using an alkaline medium for centrifugation. The olein fractions obtained
have been found to be free of phosphatides and the free fatty acids reduced to as low as 0.02%. Metal-scavenging agents have
also been added to the medium in an attempt to remove copper and iron. The development of this process into a continuous one
has been demonstrated on the AlfaLaval LAPX 202 Separator. Fractionation of crude palm oil using a density gradient provides
seven fractions of different characteristics. The iodine values vary from 37.5 to 57.4 and the unsaturated fatty acids range
from 32.7% to 51.2%. Triglyceride analysis by carbon numbers shows great differences in the C48 and C52 constituents of the fractions.
aThe volume ratio of oil to medium in each case was 1:1.
The separation involved the oil and wax. 相似文献
4.
The curing kinetics of bismaleimide modified with diallylbisphenol A were investigated for different ratios of 1,1′‐(methylene di‐4,1‐phenylene) bismaleimide and diallylbisphenol A with differential scanning calorimetry. Multiheating‐rate and isothermal methods were used to study the kinetics of the curing process. The results indicated that the activation energy changed with the extent of conversion. The activation energy obtained by the multiheating‐rate method was higher than that obtained by the isothermal method. Two kinetic models (autocatalytic and nth‐order) were successfully used to model the curing process. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2229–2240, 2003 相似文献
5.
The Tg‐conversion relationship, during the thermal curing of different stoichiometric formulations of 1,1′‐(methylene‐di‐4,1‐phenylene) bismaleimide (BMI), modified with o,o′‐diallyl bisphenol A (DABA), was investigated. The DiBenedetto equation was used to model this relationship for the formulation of DABA‐1 (BMI : DABA, 1 : 1). Based on this model, the Tg‐conversion relationship of formulation DABA‐0.5 (BMI : DABA, 1 : 0.5) was modeled. The high consistency between the model curve and experimental data showed that the change of Tg, attributed to copolymerization between BMI and DABA in DABA‐0.5, in the low‐conversion regime, was the same as that in DABA‐1. This also verifies that, for the formulation DABA‐0.5, copolymerization and homopolymerization do not overlap with each other. The reactions progressed sequentially and homopolymerization occurred after completion of copolymerization. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3244–3247, 2004 相似文献
6.
A novel approach was undertaken in producing porous AlN microelectronics tapes with high thermal conductivity and low dielectric constant. This method essentially utilised polymer micro-spherical powders that were used as a sacrificial mould to introduce controlled porosity into the green tapes during pyrolysis. The Al2O3-rich porous green tapes were then reaction sintered at 1680 °C for 12 h to achieve porous AlN tapes. This work builds upon the previously developed novel reaction sintering process that densified and converted Al2O3-rich tapes (Al2O3–20 wt.% AlN–5 wt.% Y2O3) to AlN tapes at a relatively low sintering temperature of 1680 °C. The sintering behaviour of the porous tapes was investigated, and the effects of the microspheres particle size and volume addition were studied. The microspheres successfully contributed to the significant reduction of tape density by porosity, and this contributed to lowering its dielectric constant. Dielectric constant of the AlN tapes were reduced to about 6.8–7.7 whilst thermal conductivity values were reasonable at about 46–60 W/m K. Coefficient of thermal expansion (CTE) values showed a linear trend according to phase composition, with the porous AlN tapes exhibiting CTE values of (4.4–4.8)×10−6 °C−1, showing good CTE compatibility with silicon, at 4.0×10−6 °C−1. The added porosity did not significantly affect the CTE values. 相似文献
7.
8.
Existence of triple positive solutions of two-point right focal boundary value problems on time scales 总被引:2,自引:0,他引:2
We consider the following boundary value problem, (−1)n−1yΔn(t)=(−1)p+1F(t,y(σn−1(t))),t[a,b]∩T, yΔn(a)=0,0≤i≤p−1, yΔn(σ(b))=0,p≤i≤n−1,where n ≥ 2, 1 ≤ p ≤ n - 1 is fixed and T is a time scale. By applying fixed-point theorems for operators on a cone, existence criteria are developed for triple positive solutions of the boundary value problem. We also include examples to illustrate the usefulness of the results obtained. 相似文献
9.
Juqing Liu Zongqiong Lin Tianjun Liu Zongyou Yin Xiaozhu Zhou Shufen Chen Linghai Xie Freddy Boey Hua Zhang Wei Huang 《Small (Weinheim an der Bergstrasse, Germany)》2010,6(14):1536-1542
Highly reduced graphene oxide (rGO) films are fabricated by combining reduction with smeared hydrazine at low temperature (e.g., 100 °C) and the multilayer stacking technique. The prepared rGO film, which has a lower sheet resistance (≈160–500 Ω sq−1) and higher conductivity (26 S cm−1) as compared to other rGO films obtained by commonly used chemical reduction methods, is fully characterized. The effective reduction can be attributed to the large “effective reduction depth” in the GO films (1.46 µm) and the high C1s/O1s ratio (8.04). By using the above approach, rGO films with a tunable thickness and sheet resistance are achieved. The obtained rGO films are used as electrodes in polymer memory devices, in a configuration of rGO/poly(3‐hexylthiophene) (P3HT):phenyl‐C61‐butyric acid methyl ester (PCBM)/Al, which exhibit an excellent write‐once‐read‐many‐times effect and a high ON/OFF current ratio of 106. 相似文献
10.
A. I. Y. Tok F. Y. C. Boey M. K. A. Khor 《Journal of Materials Engineering and Performance》1999,8(4):469-472
The production of ceramic green tapes is integral to the production of multilayer ceramic packages and capacitors. This article
presents a batch type process for producing alumina ceramic green tape down to 150 μm thickness. The process parameters relevant
to the precise control of the thickness of an aluminabased ceramic tape have been investigated using a float glass tape caster.
Results indicate that the cast tape thickness was dependent on the blade gap until it reached a limiting value. This limiting
thickness in turn was dependent on the casting speed, with a higher speed producing thinner tapes. Optimal casting was shown
to exist when the blade gap was set at or beyond the limiting value, with the casting speed the controlling factor for the
final thickness. 相似文献