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排序方式: 共有168条查询结果,搜索用时 31 毫秒
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The moisture barrier property of AlxOy coated poly(ethylene terephthalate) (PET), poly(ethylene naphthalate) (PEN) and poly(carbonate) (PC), have been investigated. The differences in the morphology of the AlxOy sputtered grown on these substrate were investigated using atomic force microscopy (AFM). The initial growth of the AlxOy followed closely the topology of the substrate and an amplified roughness was observed. In the fully grown AlxOy, the comparative roughness followed that of the substrates. It has been found that a single layer AlxOy improved the moisture barrier of PET by an order of magnitude, PC by two orders of magnitude while no improvement was observed for PEN. UV-ozone treatment on PC further improved the moisture barrier, while no improvement was observed for PET and PEN. The comparative effects of the substrate surface roughness and surface energy on the moisture barrier are discussed. 相似文献
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4.
JieLiang Bi-qianLiu 《高分子科学》2005,(1):83-92
Plasma-induced surface graft copolymerization of acrylic acid on polypropylene non-woven fabric (PP-g-AA) and polypropylene membrane were reported. The extents of grafting were controlled by the plasma and polymerization condition. Hexadecyltrimethyl ammonium bromide was then coupled with the carboxyl group of PP-g-AA to obtain a polyion complex (PIC). At last, CF4 plasma was used to give PICs hydrophobic property. The moisture regain and water-repellency of the processed PICs was investigated. The surfaces were characterized using ATR FT-IR and XPS. The result indicates that the products have very high ability to adsorb moisture, even better than cotton fiber. At the same time, the products show excellent hydrophobic property, which can‘t be wetted by those reagents whose surface tensions were higher than 327mN/m. 相似文献
5.
An accurate primary Fourier transform infrared (FTIR) method for the determination of moisture in mineral and ester based lubricants has been developed based on the extraction of moisture into dry acetonitrile. FTIR evaluation of acetonitrile extracts from new and used lubricants as well as common lubricant additives and contaminants which might co-extract indicated that phenolic constituents interfered significantly with moisture measurements. By measuring moisture at 3676 cm−1 on the shoulder of the asymmetric OH stretching band, spectral interferences from extracted phenolic constituents were minimized. The spectra of calibration standards (0-2100 ppm), prepared by gravimetric addition of water to dry acetonitrile, were recorded in a 1000-μm CaF2 transmission flow cell and produced linear standard curves having an S.D. of ∼±20 ppm. Lubricant sample preparation involved the vigorous shaking (20 min) of a 1:1.5 (w/v) mixture of lubricant and dry acetonitrile, centrifugation to separate the phases, acquisition of the FTIR spectrum of the upper acetonitrile layer, and subtraction of the spectrum of the dry acetonitrile used for extraction. A Continuous Oil Analyzer and Treatment (COAT®) FTIR system was programmed to allow the automated analysis of acetonitrile extracts, and the methodology was validated by analyzing 58 new and used oils, independently analyzed by the Karl Fischer (KF) method. Linear regression of FTIR versus KF results for these oils produced a linear plot with a between-method S.D. of ±80 ppm. As implemented on the COAT® system, this FTIR method is capable of analyzing 72 acetonitrile extracts/h and provides a high-speed alternative to the KF titrimetric procedures for the determination of water in lubricants. 相似文献
6.
Synthesis of silanized polyether urethane hybrid systems. Study of the curing process through hydrogen bonding interactions 总被引:1,自引:0,他引:1
Different types of silanized polyurethanes (SPUR) were prepared in two ways: the first type (a), by reacting a polyether diol with an isocyanatesilane and the second type (b) by reacting it with diisocyanate (IPDI) and afterwards with aminosilane. These systems are able to cure with atmospheric moisture and, as a consequence, a tridimensional hybrid structure is formed where the inorganic and organic phases are bonded with covalent bonds. The evolution of the curing process in both systems has been monitored by means of Fourier transform infrared spectroscopy, through the changes observed in the carbonyl stretching vibration region. The results obtained show that the SPURs of kind (b) present stronger hydrogen bonding interactions as a consequence of urea groups present in the final structure. Moreover, given the proximity of both urethane and urea groups to alkoxysilane end groups, during the alkoxysilane curing process these groups are forced to approximate themselves even further and therefore the reticulation process leads to an increase of the self association of urethane and urea groups.Finally, DSC has been used to measure Tg values of the systems studied before and after the curing process. The obtained results have confirmed the main conclusions obtained in FTIR analysis. 相似文献
7.
Miaofeng Huang Aihua Tang Zhenyin Wang Jingkun Shi Xiaoping Jiang Chubin Wan Xin Ju 《中国化学快报》2021,32(6):2009-2012
Aqueous electrolytes are safe, economic, and environmentally friendly. However, they have a narrow potential window. On the other hand, organic electrolytes exhibit good thermodynamic stability but are inflammable and moisture sensitive. In this study, we prepared water–PEG–lipid ternary electrolytes(TEs). To combine the advantages of water, polyethylene glycol(PEG) and propylene carbonate(PC). The nonflammable mixed electrolytes exhibited a wide potential window of about 2.8 V due to the beneficial effects of PEG and PC. Using these TEs, a lithium manganate–active carbon ion capacitor could be operated at 2.4 V with an energy density of 32 Wh/kg, based on the total active electrode material(current density of 3.3 m A/cm~2). This value was significantly higher than that achieved using an aqueous electrolyte, thereby rationalizing the higher energy density. 相似文献
8.
A new one-step technique to measure the effect of ambient humidity on powder resistivity has been previously presented. In this article, we provide more experimental data obtained with five different powders. One-step measurements and traditional multi-step measurements were performed. Also, additional measurements were performed using standard resistivity cell. Results were compared and it could be concluded that the new technique provided meaningful results although significant hysteresis was observed during humidification and drying cycles. Finally, charging of the powder was also measured and it was noticed that it decreases with decreasing resistivity and increasing humidity. 相似文献
9.
Wenzhan Yang Rahul Manek William M. Kolling Marius Brits Wilna Liebenberg 《Supramolecular chemistry》2013,25(6):485-496
In this study, the thermal behavior of three hydrated water-soluble 4-sulphonato calix[n]arenes was investigated. The melting points, heats of fusion, and heats of solution of the calix[4]arene, calix[6]arene and calix[8]arene were 277, 262, and 270°C; 192, 242 and 351 kJ/mol; and 30, 58 and 63 kJ/mol, respectively. Lower heat of fusion, smaller increase in entropy and smaller heat of solution of the calix[4]arene compared to the calix[6]arene and calix[8]arene showed that less heat was required to break up the crystal lattice of the smaller macromolecule. This apparent anomaly is rationalized in terms of smaller cooperativity of interaction between the molecules of calix[4]arene in the crystal lattice, although the strength of the individual interactions is stronger as evidenced by the higher melting point. TGA analysis indicated that about 17–20% of water was associated with the calix[n]arenes. Both TGA and hot stage microscopy results indicated that upon heating these molecules underwent stepwise water loss. TGA kinetics showed that the 4-sulphonato-calix[8]arene lost water easier than the other two calixarenes. The moisture adsorption behavior of all calixarenes followed type II isotherms. For the same amount of material, the calix[6]arene adsorbed more moisture than the calix[4]arene and the calix[8]arene. Moreover, dehydrated less crystalline 4-sulphonic-calix[n]arenes powders are hydroscopic. 相似文献
10.
The first principle computational screening was performed to investigate the effect of selected dopants for Li3PS4 sulfide solid electrolyte on its ionic conductivity and stability toward moisture. The results suggest that substitution P5+ using isovalent cations whose electronegativity (EN) value is closer to the value of S has more significant effects on the ionic conductivity, whereby W5+ and Sb5+ can improve most. Similarly, aliovalent cation substitutions with compensating changes in the lithium-ion concentration, particularly those with a lower oxidation state and higher EN, such as Cu2+, effectively enhance the lithium-ion conductivity in this structure. For cation dopants, it is found that ionic conductivity improvement of Li3PS4 is the synergetic effect of EN and oxidation number of the dopant as well as the material's lattice parameter change. Oxides of the considered cation dopants can also improve the ionic conductivity of the material but have much lower lithium-ion conductivity than the cases of cation dopants. However, the metal oxide dopants, particularly those derived from soft Lewis' acid cations, show a marginal improvement in moisture stability of the Li3PS4 electrolyte. The effect of halides and metal halide dopants on the lithium-ion conductivity and moisture stability of Li3PS4 electrolyte are also studied. It is found that metal halides are more effective than any other dopants in improving the ionic conductivity of Li3PS4. 相似文献