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71.
Gerald W. Buchanan Rufus Smits Giles Santyr Mihai-Raul Gherase 《Journal of fluorine chemistry》2004,125(10):1457-1460
Sucrose octaoleate-F104 has been prepared from sucrose and the acid chloride of RF-oleic acid-F13 in 86% yield using dry pyridine as solvent. The product has been characterized by MALDI-TOF mass spectrometry and and NMR methods. Some preliminary NMR results are included using hyperpolarized xenon gas dissolved in an aqueous emulsion containing egg yolk phospholipid and the octaester. The in vitro spin lattice relaxation time of dissolved xenon as well as the chemical shift suggest that highly fluorinated sucrose polyesters (HFSPE’s) may be promising molecules for use as part of in vivo delivery systems for hyperpolarized xenon. 相似文献
72.
The phase diagrams of S1570–Brij 97/oleic acid/water system at two different S1570/Brij 97 mass ratios of 1/1 (system S) and 7/3 (system P) were determined at 37°C, respectively. The microstructures and rheological properties of liquid crystals at constant surfactants/water mass ratio of 1/1 were studied with increase in oil content. Small-angle x-ray scattering measurements showed that system S exhibited a typical lamellar liquid crystals and the repeat distance (d) decreased as oil content increased. While for system P, two couples of scattering peaks were observed when oil content reached 28 wt%. This indicated that adding oil content may give rise to a multilamellar structures in the higher S1570/Brij 97 mass ratio system. The rheological tests indicated that a transition from elastic gel-like properties to viscoelastic liquid-like properties appeared in both system S and P when oil content reached 20 wt%, corresponding to the polarizing optical microscopy textures changing from oily streak to cruciate flower. This supplies a way to adjust structure, rheological properties, and even phase transition by altering the S1570/Brij 97 mass ratio and oleic acid content in system. 相似文献
73.
Emmanuelle Pioger Denis Wouessidjewe Dominique Duchêne Svetla Bogdanova 《Journal of inclusion phenomena and macrocyclic chemistry》1998,30(2):151-161
The influence of the water structure promoters, mannitol and sucrose, on the indomethacin/-cyclodextrin inclusion process at different pH values was evaluated using the phase solubility method and circular dichroism spectroscopy. The effect of mannitol and sucrose on the total solubilizing activity of -cyclodextrin as well as on the stabilization of the complex was moderate, and depended strongly on the pH value of the medium. The most pronounced effect on the association constant of the indomethacin inclusion compound was observed in KCl/HCl buffer of pH 1.6, because mannitol and sucrose, in the absence of -cyclodextrin, approximately double the indomethacin solubility so that the constant value decreases. On the other hand, a very strong complex formation between indomethacin and -cyclodextrin was observed in acid medium (KCl/HCl buffer, pH = 1.6), a fact not much discussed in the literature. The apparent association constant of the inclusion compound formed in the absence of mannitol or sucrose was found to be of the same order of magnitude as for the complex formed at pH 6.8. Changes in the optical activity of the indomethacin/-cyclodextrin inclusion complex were registered in the presence of sucrose, which interacts more strongly than mannitol with water molecules, and could probably adhere to the surface of the inclusion complex, thus changing its configuration and environment. 相似文献
74.
75.
Long‐term preservation of hemoglobin (Hb) vesicles, the so‐called artificial red cell (ARC), in dry powder was studied. Carbonylhemoglobin (COHb) was encapsulated in the vesicle of 1,2‐bis(2,4‐octadecadienoyl)‐sn‐glycero‐3‐phosphocholine (DODPC) and the polymerizable membrane components were polymerized by γ‐ray irradiation. The obtained ARC suspension was then freeze‐dried in the presence of sucrose. The factors influencing the shelf‐life of the freeze‐dried ARC, such as sucrose concentration, moisture and storage temperature, were elucidated. After storage in the dry state for more than one year, the oxygen‐carrying capacity was recovered by rehydration of the freeze‐dried ARC with distilled water and substitution of the carbon monoxide ligand with oxygen. Copyright © 1999 John Wiley & Sons, Ltd. 相似文献
76.
Nitin S. Patil Yanzi Li David G. Rethwisch Jonathan S. Dordick 《Journal of polymer science. Part A, Polymer chemistry》1997,35(11):2221-2229
A series of degradable hydrogels based on different vinyl monomers such as acrylamide, sucrose-1′-acrylate, and acrylic acid were synthesized using sucrose-6,1′-diacrylate (SDA) as a crosslinking agent. SDA was prepared by enzymatic transesterification of vinyl acrylate with sucrose in pyridine. Base catalyzed hydrolysis of SDA in aqueous solution was studied as a function of pH. As expected, hydrolysis of SDA was faster at higher pHs such that poly(acrylamide), poly(sucrose 1′-acrylate), and poly(acrylic acid) hydrogels underwent substantial degradation at and above pH 7, 9, and 13, respectively. The degradation was characterized by changes in the swelling ratios of the hydrogels indicating breakage of the crosslinking agent. Degradation of the hydrogels at their chemically stable pHs was studied in presence of enzymes. Enzymes, including pepsin and a fungal Lipase, were able to degrade the poly(acrylamide) hydrogel at pH 4 and 5, respectively. Poly(acrylic acid) hydrogel was degraded in presence of a fungal protease at pH 7.8. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 2221–2229, 1997 相似文献
77.
Summary: Vinyl sugar ester, 1′-O-vinyladipoyl-sucrose, was synthesized using sucrose and DVA (divinyl adipate) in organic medium (dimethylformamide), catalyzed by protease from Bacillus subtilis. Several reaction conditions were examined by means of qualitative analysis (TLC). The monomer obtained has undergone chemical polymerization with potassium persulfate and hydrogen peroxide to produce an amphiphilic polymer having sugar branches. The monomer was characterized by 13C-NMR and FTIR spectra. The IR analysis confirmed the synthesis of the poly (1′-O-vinyladipoyl-sucrose). 相似文献
78.
利用Anton Paar DMA55精密数字密度计测定了288.15, 298.15和308.15 K甘氨酰甘氨酸在蔗糖-水混合溶剂中的密度, 计算了甘氨酰甘氨酸的表观摩尔体积VΦ和极限偏摩尔体积 , 得到了其由纯水溶剂转移至混合溶剂中的迁移偏摩尔体积Δtrs 和理论水化数Nh.根据共球交盖模型, 讨论了迁移偏摩尔体积和水化数的变化规律.结果表明, 甘氨酰甘氨酸带电中心与蔗糖之间的结构相互作用对其迁移体积有正贡献, 且占主导地位.甘氨酰甘氨酸的迁移偏摩尔体积为正值, 且随着蔗糖浓度的增大而增大; 理论水化数随温度升高、蔗糖浓度的增大而减小; 温度升高, 极限偏摩尔体积增大, 迁移偏摩尔体积变化很小. 相似文献
79.
Temperature modulated DSC (TMDSC) at low temperatures requires attention to the selection of experimental parameters that
are within the capability of the instrumentation as well as special care in calibration of heat capacity measurement when
high precision is required. Data are presented to facilitate selection of appropriate modulation periods and amplitudes at
low temperature when using a mechanical cooling accessory. The standard error of the mean heat capacity measurement for a
sapphire standard increased with decreasing temperature, decreasing period, and increasing pan mass. For ice in hermetically
sealed pans, the standard error of the mean heat capacity measurement was larger than for sapphire and did not follow a predictable
trend with changes in temperature and period of modulation. This was attributed to changes in sample geometry between successive
measurements due to melting and resolidification. A simple one-point temperature calibration by TMDSC may be unsuitable for
precise measurement of heat capacity because of the random error caused by sample placement and the systematic error caused
by cell asymmetry, temperature dependence of the calibration constant, and different sample thermal conductivities. An alternative
calibration procedure using standard DSC and either a linear or second order fit of the calibration constant over the temperature
range of interest is proposed.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
80.
丙氨酸在蔗糖-水混合溶剂中的焓对相互作用 总被引:3,自引:0,他引:3
利用LKB2277生物活性检测仪测定了298.15 K时丙氨酸分别在不同组成的蔗糖- 水混合溶剂中的稀释焓,利用McMillan-Mayer理论,计算了丙氨酸在不同组成的蔗 糖-水混合溶剂中的焓对相互作用系数h_2,并与其在葡萄糖-水混合溶剂中的焓对 相互作用系数h_2进行了比较。结果表明,丙氨酸的h_2分别在葡萄糖和蔗糖的摩尔 分数为0.1009和0.05843处出现极大值,极值点位置的不同与糖分子所含羟基数目 的多少有关,根据溶质-溶质相互作用和溶质-溶剂相互作用对结果进行了解释。 相似文献