全文获取类型
收费全文 | 363篇 |
免费 | 16篇 |
国内免费 | 5篇 |
专业分类
电工技术 | 1篇 |
综合类 | 24篇 |
化学工业 | 224篇 |
金属工艺 | 1篇 |
机械仪表 | 16篇 |
建筑科学 | 2篇 |
矿业工程 | 1篇 |
能源动力 | 7篇 |
轻工业 | 61篇 |
水利工程 | 1篇 |
石油天然气 | 26篇 |
无线电 | 2篇 |
一般工业技术 | 17篇 |
自动化技术 | 1篇 |
出版年
2024年 | 3篇 |
2023年 | 8篇 |
2022年 | 4篇 |
2021年 | 8篇 |
2020年 | 8篇 |
2019年 | 11篇 |
2018年 | 11篇 |
2017年 | 12篇 |
2016年 | 12篇 |
2015年 | 13篇 |
2014年 | 13篇 |
2013年 | 20篇 |
2012年 | 26篇 |
2011年 | 19篇 |
2010年 | 16篇 |
2009年 | 13篇 |
2008年 | 14篇 |
2007年 | 19篇 |
2006年 | 21篇 |
2005年 | 21篇 |
2004年 | 17篇 |
2003年 | 6篇 |
2002年 | 13篇 |
2001年 | 12篇 |
2000年 | 6篇 |
1999年 | 6篇 |
1998年 | 8篇 |
1997年 | 11篇 |
1996年 | 5篇 |
1995年 | 4篇 |
1994年 | 6篇 |
1993年 | 8篇 |
1992年 | 3篇 |
1991年 | 4篇 |
1990年 | 1篇 |
1982年 | 1篇 |
1978年 | 1篇 |
排序方式: 共有384条查询结果,搜索用时 15 毫秒
1.
Phase separation during polymerization was studied in a model system consisting of a diepoxide based on diglycidyl ether of bisphenol A (DGEBA), variable amounts of ethylenediamine (EDA) and the mass of castor oil (CO) necessary to obtain a mass fraction equal to 0-15 in a final system where the stoichiometric ratio of amine to epoxy equivalents, r, was equal to 1. A two-step polymerization process was performed by curing first a system with r = 0-5, during variable times before phase separation, and then carrying the system to r = 1. Thermodynamic analysis of samples with different r values led to a linear relationship between the Flory-Huggins interaction parameter and r. The concentration (P) and average size (D?) of dispersed-phase particles followed opposite trends, i.e. P increased while D? decreased, when either r was increased or the time of curing in the first step of a two-step process was decreased. This was explained by assuming that the competition between nucleation and growth was determined by the viscosity at the cloud point, ηcp. Low values of ηcp favoured growth over nucleation and led to fewer but larger particles. 相似文献
2.
HPP-1型皮革加脂剂的研制和应用 总被引:1,自引:0,他引:1
本文概述了以磷酸化蓖麻油和羟化磷脂为基础的皮革加脂剂的研制,讨论了合成反应、产品配伍、应用试验等工艺过程。 相似文献
3.
Castor oil dehydration kinetics 总被引:4,自引:0,他引:4
F. Seniha Guner 《Journal of the American Oil Chemists' Society》1997,74(4):409-412
The dehydration reaction kinetics of castor oil was investigated with sodium bisulfate-sodium bisulfite mixture (SB-SB) or
p-toluenesulfonic acid as catalyst. Reactions were carried out at 210, 220, and 230°C, and a kinetic model was determined for
each case. The reactions with SB-SB catalyst at 210 and 220°C and with p-toluenesulfonic acid at 210°C followed second-order kinetics. A first-order rate equation showed the best fit to the experimental
data for the reaction with SB-SB at 230°C. p-Toluenesulfonic acid-catalyzed reactions at 220 and 230°C were also first-order reactions. Additionally, some mathematical
equations were derived between iodine value, refractive index, viscosity, and reaction time. 相似文献
4.
研究了改性蓖麻油制备UV光固化涂料。由蓖麻油、环氧丙烯酸树脂UVR6100、光引发剂UVI6990制得的涂料具有优良的光泽、良好的柔韧性、良好的附着力与硬度,且当改性蓖麻油含量为40%时,漆膜性能最为优良。 相似文献
5.
Sajid Husain M. Kifayatullah G. S. R. Sastry N. Prasada Raju 《Journal of the American Oil Chemists' Society》1993,70(12):1251-1254
Application of13C nuclear magnetic resonance (NMR) spectroscopy for detection of castor oil (CO) in various edible oils, such as coconut oil,
palm oil, groundnut oil and mustard oil, is described. Characteristic signals observed at δ 132.4, δ 125.6, δ 71.3, δ 36.8
and δ 35.4 ppm, due to C10, C9, C12, C13 and C11 carbons of ricinoleic acid (RA) in CO, were selected for distinguishing it
from edible oils. Quantitative13C NMR spectra of oils were recorded in CDCl3 with a gated decoupling technique. The minimum detection limits for qualitative and quantitative analyses were 2.0 and 3.0%,
respectively. The proposed method is simple, nondestructive and requires no sample pretreatment. Its application to heat-abused
oils has also been demonstrated successfully without any of the interferences observed in most other methods. 相似文献
6.
Blending of two polymers in solution is a simple and cost‐effective technique to improve upon the physical and mechanical properties of the component polymers through synergism. To obtain maximum synergy in their properties, the component polymers should be miscible with each other on molecular scale. Polymer blends of complex physicomechanical properties are being actively investigated. Poly(methacrylic acid) (PMAA), a commercial polymer, yields transparent, hard, brittle, and water‐sensitive films. It has been blended with natural polymers like dextran, collagen, and gelatin to obtain films with improved physical and mechanical characteristics. Polyesteramides, which are easily synthesized from vegetable seeds oil, a sustainable resource, have found application in surface coatings. These oligomeric products do not make free standing films in the ambient condition. The polyesteramides from vegetable seeds oil can be used to obtain blend with PMMA of improved mechanical and water absorption properties. In this study, linseed oil polyesteramide (LOPEA) and dehydrated castor oil polyesteramide (DCPEA), the source oils with different unsaturation in their fatty acid chains, were blended with PMAA through mixing in solution in the ratio DCPEA/LOPEA: PMAA as 80/20, 70/30, 60/40, 50/50, 40/60, 30/70, and 20/80. In the first instance, the miscibility of the two components was investigated in solution by viscosity and ultrasonic measurements and in solid phase through differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). Moisture absorption by the blend was also studied. DCPEA and LOPEA show immiscibility with PMAA in solution phase while LOPEA with more unsaturation in the fatty acid chain of the oil was found more immiscible than DCPEA. DCPEA shows a narrow miscibility window in the solid phase while LOPEA was found immiscible with PMAA in the solid phase too. Uptake of moisture was found to be markedly reduced in the blends of DCPEA/LOPEA with PMAA. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1367–1374, 2007: 相似文献
7.
Yinzhong Guo Vijay M. Mannari Pulin Patel John L. Massingill 《Journal of Coatings Technology and Research》2006,3(4):327-331
A series of soybean oil phosphate ester polyols (SOPEP) was prepared by reaction of fully epoxidized soybean oil with phosphoric
acid and simultanoeous hydrolysis in the presence of a polar solvent. The polyols were characterized by determination of acid
value, oxirane number, hydroxyl value, molecular weight (GPC), and FTIR spectra. These polyols with varying amounts of acid
phosphate groups could be self-emulsified to form aqueous dispersions after neutralization with organic base. These aqueous
dispersion showed varying degrees of stability and their appearance ranged from opaque dispersions to translucent to clear
solutions. Waterborne coating compositions were prepared using these aqueous dispersions as principal components and their
thermally cured film properties were studied. it was found that by careful selection and formulation, SOPEPs can be successfully
used for low-VOC waterborne coating formulations. SOPEPs with 3.5% phosphate ester content showed visibly superior corrosion
resistance properties. 相似文献
8.
以N,N-二甲基苯胺,1%(按IPN质量计,下同)过氧化二苯甲酰和二丁基二月桂酸锡(简称有机锡)为固化剂,活性二氧化硅为填充剂(用量为总质量的30%),由47%的甲基丙烯酸甲酯与蓖麻油,2,4-甲苯二异氰酸酯型聚氨酯组成的IPN为基材,在25-30℃下经8-12h固化。固化材料的体积电阻率和表面电阻率可达10^13数量级,介电常数为5.5-6.0,介电损耗角正切为0.018-0.020,拉伸强度为 相似文献
9.
Interpenetrating polymer networks (IPNs) of glycerol modified castor oil polyurethane (GC‐PU) and poly(2‐ethoxyethyl methacrylate) poly(2‐EOEMA) were synthesized using benzoyl peroxide as initiator and ethylene glycol dimethacrylate (EGDM) as crosslinker. GC‐PU/poly (2‐EOEMA) interpenetrating polymer networks were obtained by transfer molding. The novel GC‐PU/poly (2‐EOEMA) IPNs are found to be tough films. These IPNs are characterized in terms of their resistance to chemical reagents thermal behavior (DSC, TGA) and mechanical behavior, including tensile strength, Young's modulus, shore A hardness, and elongation. The morphological behavior was studied by scanning electron microscopy. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 1029–1034, 2004 相似文献
10.
采用种子乳液聚合方法合成了蓖麻油基水性聚氨酯-聚丙烯酸酯复合乳液,通过激光散射法、透射电镜(TEM)、傅里叶红外光谱(FTIR)对该复合材料进行了表征。结果表明,该乳液具有核壳结构,并且随着原料中蓖麻油与聚己二酸丁二醇酯二醇(PBA)摩尔比的增加,复合材料的耐水性逐渐提高;聚丙烯酸酯的引入对乳液的粒径和胶膜性能均有影响,合适的PA/PU摩尔比在2∶3~1∶1之间;当COOH基质量分数为1.2%时,加入2%的十二烷基硫酸钠(SDS),乳液外观由乳白色变为透明色,且凝胶量少,乳液的稳定性好。 相似文献