全文获取类型
收费全文 | 85篇 |
免费 | 20篇 |
国内免费 | 15篇 |
专业分类
化学 | 64篇 |
晶体学 | 2篇 |
力学 | 2篇 |
综合类 | 8篇 |
数学 | 9篇 |
物理学 | 35篇 |
出版年
2024年 | 1篇 |
2023年 | 2篇 |
2022年 | 9篇 |
2021年 | 8篇 |
2020年 | 4篇 |
2019年 | 10篇 |
2018年 | 3篇 |
2017年 | 4篇 |
2016年 | 4篇 |
2015年 | 6篇 |
2014年 | 5篇 |
2013年 | 4篇 |
2012年 | 9篇 |
2011年 | 7篇 |
2010年 | 4篇 |
2009年 | 2篇 |
2008年 | 5篇 |
2007年 | 7篇 |
2006年 | 5篇 |
2005年 | 2篇 |
2004年 | 3篇 |
2003年 | 1篇 |
2002年 | 1篇 |
2001年 | 3篇 |
1999年 | 1篇 |
1998年 | 1篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1992年 | 3篇 |
1988年 | 2篇 |
1986年 | 2篇 |
排序方式: 共有120条查询结果,搜索用时 15 毫秒
31.
A method to determine activity coefficients of electrolytes in mixed solvent is described which makes use of ion-selective electrode(s) (ISE) and in which a concentrated electrolyte solution is continuously added. Activity coefficients for HCl in methanol-water mixtures containing 0, 10, 20, 30, 50, 70, and 90 weight percent methanol at 25, 35 and 45°C were calculated using the Pitzer equation, and the electromotive force (emf) data of the cell:
The experimental results agree well with literature values indicating that the proposed method is procise and reliable. 相似文献
32.
Yanru Yuan Ruo Yuan Yaqin Chai Ying Zhuo Yintao Shi Xiulan He Xiangmin Miao 《Electroanalysis》2007,19(13):1402-1410
A novel reagentless amperometric immunosensor for the determination of alpha‐fetoprotein (AFP) was prepared by immobilizing TiO2 colloids on Prussian blue (PB) modified platinum electrode, which yielded a positively charged interface with strong adsorption to deposit gold nanoparticles for immobilization of alpha‐fetoprotein antibody (anti‐AFP). The factors influencing the performance of the proposed immunosensors were studied in detail. Under the optimized conditions, cyclic voltammograms determination of AFP showed a specific response in two concentration ranges from 3.0 to 30.0 ng/mL and from 30.0 to 300.0 ng/mL with a detection limit of 1.0 ng/mL at a signal‐to‐noise ratio of 3. The proposed immunosensor exhibited high selectivity, good reproducibility, long‐term stability (>2 months) and good repeatability. 相似文献
33.
Fan Y Cao M Yuan G Wang Y Yan H Han CC 《Journal of colloid and interface science》2006,299(2):928-937
The aggregation behavior of mixed systems of sodium bis(2-ethylhexyl) sulfosuccinate (AOT) or sodium bis(4-phenylbutyl) sulfosuccinate (SBPBS) with nonionic surfactant pentaethylene glycol mono-n-dodecyl ether (C12E5) have been studied by means of steady-state fluorescence, electrical conductivity, dynamic light scattering, transmission electron microscopy, electrophoretic light scattering and pyrene solubilization measurements. The critical concentrations for aggregation, micropolarity, mobility, solubilization capacity and morphology of aggregates are characterized. Two critical concentrations for aggregation are observed in the mixed surfactants, which may correspond to the formation of different kinds of aggregates. Moreover, it is more favorable for AOT-C12E5 to form mixed vesicles compared to SBPBS-C12E5 at higher mole fraction of C12E5. In addition, it is revealed that SBPBS-C12E5 mixture has larger solubilization capacity for pyrene than AOT-C12E5 system. 相似文献
34.
Fan Y Li Y Yuan G Wang Y Wang J Han CC Yan H Li Z Thomas RK 《Langmuir : the ACS journal of surfaces and colloids》2005,21(9):3814-3820
The micellization process of sodium bis(4-phenylbutyl) sulfosuccinate (SBPBS) has been studied compared to that of sodium bis(2-ethylhexyl) sulfosuccinate (AOT) by surface tension, steady-state fluorescence, microcalorimetry, dynamic light scattering (DLS), and transmission electron microscopy (TEM) measurements. Meanwhile, the interaction of these two surfactants with hydrophobically modified poly(acrylamide) (HMPAM) was investigated. The results show that the surface tension at the critical micelle concentration (cmc) of SBPBS and the micropolarity probed by pyrene in SBPBS aggregates are both larger than those of AOT. The enthalpy change of micellization (DeltaH(mic)) of AOT is endothermic, while it is exothermic for SBPBS. Strong pi-pi interaction among the adjacent phenyl groups of SBPBS molecules is likely the cause for the above properties of SBPBS. Moreover, vesicles are observed for AOT and SBPBS by DLS and TEM, especially for AOT, whose micelle-vesicle transition has been first confirmed by its calorimetric curve. In the surfactant-HMPAM systems, the critical aggregation concentration (cac), the saturation concentration of aggregation (C(2)), and the thermodynamic parameters of binding have also been determined. The conclusion may be drawn that the binding strength of SBPBS onto HMPAM is stronger than that of AOT. 相似文献
35.
Preparation,characterization, and bioavailability of a phosphorylated human‐like collagen calcium complex 下载免费PDF全文
Chenhui Zhu Yanru Chen Jianjun Deng Wenjiao Xue Xiaoxuan Ma Junfeng Hui Daidi Fan 《先进技术聚合物》2015,26(10):1217-1225
The aim of this study was to determine whether a phosphorylated human‐like collagen calcium (PHLC–Ca) complex showed a higher bioavailability than other calcium supplements. To improve the calcium‐binding ability of human‐like collagen (HLC), modified HLC was prepared by introducing a reactive phosphate group using a dry‐heating method, followed by the formation of PHLC–Ca in MOPS buffer. PHLC–Ca was characterized using atomic absorption spectrophotometry, Fourier transform infrared (FTIR), fluorescence quenching, circular dichroism (CD), and ultraviolet–visible absorption (UV–vis) spectroscopy. The calcium uptake test showed that the bioavailability of PHLC–Ca was higher than that of CaCl2 and G‐Ca. Data from a mouse model of osteoporosis suggested that PHLC–Ca is superior for treating osteoporosis than CaCl2 or G‐Ca. These results indicate that PHLC–Ca is a desirable calcium supplement for use in daily life and clinical application. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
36.
Based on the vectorial angular spectrum representation of Maxwell equations and the method of stationary phase, analytical expressions are derived for the TE term, TM term and whole energy flux of a hard-edged diffracted modified Laguerre–Gaussian beam (MLGBs) in the far field, respectively. It is shown that the evolutive energy flux not only depends on the beam order, initial waist width but also relates to the truncated parameter. Furthermore, influences of the truncated parameter on the discrepancies of energy flux distributions between paraxial and non-paraxial cases are also analyzed for different selections of the initial beam width. 相似文献
37.
Rapid and efficient enantioseparation of (S)‐amlodipine by surface‐imprinted core–shell polymer microspheres 下载免费PDF全文
Shenzhi Lai Chunyan Chen Xiaoli Ouyang Yanru Qin Changqun Cai Xiaoming Chen 《Journal of separation science》2016,39(22):4354-4359
We present a protocol for the preparation of surface‐imprinted polymer microspheres by core–shell precipitation polymerization for the enantioseparation of (S)‐amlodipine. In this work, submicron mesoporous silica microspheres were prepared with gemini cationic surfactant as soft template. Molecularly imprinted polymers were coated on the silica supports with a low level of crosslinking, and the thickness of the thin‐walled imprinted shell was about 45 nm. The material showed fast binding kinetics for (S)‐amlodipine (within only 20 min for complete equilibrium), and the saturation adsorption capacity reached 309.2 mg/g, indicating the good accessibility of binding sites and improved mass transfer for target molecule. The imprinted microspheres exhibited an appreciable enantiomeric excess of (S)‐amlodipine of 11.3% when used as a glass chromatography column for the enantioseparation of (S)‐amlodipine from amlodipine besylate without extra chiral additives. The surface‐imprinted materials display potentially amplification for industrial enantioseparation of (S)‐amlodipine. 相似文献
38.
Yang T Su G Ning C Deng J Wang F Zhang S Ren X Huang Y 《The journal of physical chemistry. A》2007,111(23):4927-4933
The most populated conformer of tetrahydrofuran (C(4)H(8)O) has been diagnosed as the Cs conformer in the present study, jointly using experimental electron momentum spectroscopy (EMS) and quantum mechanics. Our B3LYP/6-311++G** model indicates that the C1 conformation, which is one of the three possible conformations of tetrahydrofuran produced by pseudorotation in the gas phase, is a transition state due to its imaginary frequencies, in agreement with the prediction from a recent ab initio MP2/aug-cc-pVTZ study (J. Chem. Phys. 2005, 122, 204303). The study has identified the fingerprint of the highest occupied molecular orbital (HOMO) of the C(s) (12a') conformer as the most populated conformer. The identification of the C(s) structure, therefore, leads to the orbital-based assignment of the ionization binding energy spectra of tetrahydrofuran for the first time, on the basis of the outer valence Green function OVGF/6-31G* model and the density functional theory (DFT) SAOP/ET-PVQZ model. The present study explores an innovative approach to study molecular stabilities. It also indicates that energetic properties are not always the most appropriate means to study conformer-rich biological systems. 相似文献
39.
A review on the dewaterability of bio-sludge and ultrasound pretreatment 总被引:14,自引:0,他引:14
Bio-sludge, which contains large quantities of water, biomass and extracellular polymeric substances (EPS), is difficult to be dewatered as a "super-compactable" sludge [Water Res. 35 (5) (2001) 1358]. Reported water content in bio-sludge was commonly about 80-90% wt after dewatering process. The EPS and the form of water in sludge influences the structure of sludge. Adding cationic fluctuations can change the form of water in sludge and increase the velocity of dewatering process, but has little influence on the final water content. According to Bien's work [Water Sci. Technol. 36 (4) (1997) 287], a combination of ultrasound or other method could agglomerate the sludge, improve the activities of biomass [Ultrasonics 38 (2000) 711; Ultrasonics 40 (2002) 25], enhance anaerobic process [Water Sci. Technol. 36 (11) (1997) 155; Water Sci. Technol. 36 (11) (1997) 121; Water Res. 35 (8) (2001) 2003; Water Sci. Technol. 36 (12) (1997) 117] and decrease over 10% final water content of sludge. The mechanisms of ultrasonic influence on sludge are not very clear, but the application of ultrasound to industrial process is relatively easy and possible. 相似文献
40.