全文获取类型
收费全文 | 57篇 |
免费 | 3篇 |
国内免费 | 28篇 |
专业分类
化学 | 79篇 |
物理学 | 9篇 |
出版年
2022年 | 1篇 |
2021年 | 2篇 |
2020年 | 1篇 |
2017年 | 1篇 |
2016年 | 5篇 |
2015年 | 1篇 |
2014年 | 4篇 |
2013年 | 9篇 |
2012年 | 4篇 |
2011年 | 10篇 |
2010年 | 5篇 |
2009年 | 4篇 |
2008年 | 6篇 |
2007年 | 6篇 |
2006年 | 5篇 |
2005年 | 4篇 |
2004年 | 3篇 |
2003年 | 4篇 |
2001年 | 1篇 |
2000年 | 2篇 |
1999年 | 1篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 2篇 |
1988年 | 2篇 |
1986年 | 1篇 |
1985年 | 1篇 |
排序方式: 共有88条查询结果,搜索用时 15 毫秒
1.
2.
Surface composition and property of film prepared with aqueous dispersion of polyurethaneurea-acrylate including fluorinated block copolymer 总被引:1,自引:0,他引:1
The aqueous dispersion of polyurethaneurea-acrylate (PUA) including small amount of fluorinated block copolymers containing carboxyl groups (PATF), which can be dissolved in water, was used to make films and the surface properties of these films were examined. The experimental data show that the modified PUA film exhibits a hydrophobic surface property, although the original surface of PUA film is hydrophilic. The surface composition of the modified PUA film was measured by ATR and XPS. The results indicate that there is a concentration gradient of the fluorine groups along the lines of thickness of the modified film and towards the outmost surface layer, resulting from the migration of fluorinated blocks to the air side surface of the modified PUA film during the film formation process. However, the PUA film can not be modified effectively by adding the sodium salt of PATF, since the urethane groups in the system are easy to occupy on the surface of the film. 相似文献
3.
4.
M. N. Chai 《International Journal of Polymer Analysis and Characterization》2013,18(4):280-286
Electrical impedance spectroscopy was used to measure the conductivity of solid polymer electrolytes. From the impedance study, the highest ionic conductivity of solid polymer electrolytes based on carboxyl methylcellulose as polymer host and oleic acid as the doping salt, prepared by the solution casting method at room temperature, σr.t, is 2.11 × 10?5 S cm?1 for the sample containing 20 wt.% of oleic acid. Transference number measurement was performed to correlate the diffusion phenomena to the conductivity behavior of carboxyl methylcellulose-oleic acid solid polymer electrolytes. From the transference number measurement study, the conduction species carrier of the cation (+) is higher than that of the anion (?). Thus, the results proved that the samples are proton-conducting solid polymer electrolytes. 相似文献
5.
M. N. Hafiza A. N. A. Bashirah N. Y. Bakar 《International Journal of Polymer Analysis and Characterization》2014,19(2):151-158
This present work discusses dual-blend green polymer electrolyte (GPE)–based natural polymers, composed of carboxyl methylcellulose (CMC) and chitosan (CS), created by introducing various compositions of ammonium bromide (NH4Br) as a dopant in the system. These GPEs were successfully prepared by the solution casting technique and characterized using electrical impedance spectroscopy (EIS). From EIS measurement, the highest room-temperature conductivity is 1.21 × 10?5 Scm?1 for the sample containing 20 wt.% of NH4Br. Plot of the temperature dependence of the GPEs revealed that the system obeys the Arrhenius rule and was thermally assisted. Besides that, dielectric studies were also conducted and the data were analyzed using complex permittivity, ?*, and complex electrical modulus, M*, to determine the sample with the highest conductivity value. Thus, this study confirmed non-Debye behavior in the sample. 相似文献
6.
The fluorescence properties of a series of rare earth (Re3+ = Eu3+, Tb3+) polymeric complexes (PEK-Re3+-HLs) using three high-Tg novel carboxyl-containing polyaryletherketones (PEK) as macromolecular ligands and small molecules (HL) such as 1,10-phenanthroline (Phen), dibenzoylmethane (DBM) and 8-hydroxyquinoline (HQ) as co-ligands were investigated by means of fluorescence excitation and emission spectroscopy as well as fluorescence lifetime measurement methods. Among them, PEK-1-Re3+-Phens, in which the Re3+ ions were coordinated simultaneously with Phen and PEK-1 containing both carboxyl and bulky isopropyl groups on the polymer backbone, exhibited strong fluorescence intensities, long lifetimes, and good film-formation properties. The smooth films of PEK-1-Eu3+-Phen and PEK-1-Tb3+-Phen, cast from their DMF solutions, could emit bright red and green light under the UV lamp of 365 nm, respectively, which characteristics are of great significance for their potential applications in the large area display material fields. The excellent fluorescence properties of complexes in this study were attributed to the synergistic effects of PEK-1 ligand and Phen co-ligand. Especially, the rigid twisted structure and the bulky isopropyl substituents on PEK-1 backbone forced the coordinated rare earth ion moieties apart, and thus the probability of non-radiative decay rate of Re3+ ions at the excited levels were decreased to a large extent. 相似文献
7.
以含羧基侧基的聚芳醚酮酮醚酮酮(PEKKEKK-A)树脂为原料,二氯亚砜(SOCl2)、二氯乙烷(DCE)、吡啶为催化溶剂体系,合成带甲酰氯侧基的聚芳醚酮酮醚酮酮(PEKKEKK-C)树脂.PEKKEKK-C与甲醇、乙醇、丁醇、辛醇、苯酚等发生酯化反应,得到5种含羧酸酯侧基的聚芳醚酮酮醚酮酮(PEKKEKK-E)s.用红外光谱(FTIR)、氢核磁谱(1H-NMR)、广角X射线衍射(WAXD)、热失重(TGA)、示差扫描量热(DSC)等技术对其结构与性能进行了分析表征.结果表明,聚合物为非晶聚集态;玻璃化转变温度(Tg)在175.7~236.8℃之间,较PEKK有较大幅度提高;出现两次热失重平台,分别在335~365℃,460~505℃之间,第一次失重可能由于酯分解所致,第二次失重可能是分子主链开始分解;树脂能溶解于DMAc、NMP、二氯甲烷等普通有机溶剂中,溶剂挥发后成膜性良好,可制成透明薄膜;断裂伸长率在6.34%~15.43%之间,拉伸强度在74.68~85.35MPa之间。 相似文献
8.
9.
N-tert-Butylamides are readily converted into the corresponding carboxylic acids by simple nitrosation. The process, which occurs under mild nonaqueous conditions, leaves carboxylic esters untouched and transforms multicomponent reaction products into useful building blocks for further synthetic elaboration. 相似文献
10.
Anionic groups (AGs) on different cellulosic fiber surfaces were investigated by methylene blue (MB) and polyelectrolyte (PE) sorption, X-ray photoelectron spectroscopy (XPS), and total attenuated reflectance infrared spectrometry (FTIR-ATR). The MB sorption isotherms fitted well the Langmuir equation that gave consistent estimations of sorption capacities. FTIR-ATR showed that MB molecules had extensive accessibility to the fiber wall pores. Estimation of surface AGs by PE sorption gave much higher values than a new method combining MB sorption and XPS measurements (MB-XPS). The surface AGs in different cellulosic fibers accounted for 1-3% of the total AG content as revealed by MB-XPS. It was suggested that PE molecules can penetrate the fiber wall and form loops or unattached segments at external fiber surfaces that disrupt the PE sorption stoichiometry. The competition of MB and PE for the anionic sites in papermaking was assessed and it was shown that MB ions have a much stronger affinity to AGs than PE molecules. 相似文献