全文获取类型
收费全文 | 78篇 |
免费 | 0篇 |
专业分类
化学 | 65篇 |
晶体学 | 1篇 |
数学 | 1篇 |
物理学 | 11篇 |
出版年
2023年 | 1篇 |
2022年 | 1篇 |
2021年 | 1篇 |
2020年 | 1篇 |
2019年 | 1篇 |
2018年 | 1篇 |
2016年 | 1篇 |
2014年 | 1篇 |
2013年 | 3篇 |
2012年 | 6篇 |
2011年 | 9篇 |
2010年 | 2篇 |
2009年 | 1篇 |
2008年 | 2篇 |
2007年 | 4篇 |
2006年 | 4篇 |
2005年 | 5篇 |
2004年 | 4篇 |
2003年 | 6篇 |
2002年 | 7篇 |
2001年 | 1篇 |
2000年 | 2篇 |
1999年 | 1篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1992年 | 1篇 |
1991年 | 3篇 |
1990年 | 1篇 |
1988年 | 1篇 |
1983年 | 1篇 |
1981年 | 1篇 |
1974年 | 1篇 |
排序方式: 共有78条查询结果,搜索用时 0 毫秒
71.
We use atomistic simulations to address the question when capillary evaporation of water confined in a hydrocarbonlike slit is kinetically viable. Activation barriers and absolute rates of evaporation are estimated using open ensemble Monte Carlo-umbrella sampling and molecular dynamics simulations. At ambient conditions, the evaporation rate in a water film four molecular diameters thick is found to be of the order 10(5)(nm(2) s)(-1), meaning that water readily evaporates. Films more than a few nanometers thick will persist in a metastable liquid state. Dissolved atmospheric gas molecules do not significantly decrease the activation barrier. 相似文献
72.
13C nuclear magnetic resonance and 14N nuclear quadrupole resonance spectra of ferroelectric smectic C*liquid crystals and their non-chiral analogues allow for a microscopic determination of the polar and quadrupolar (or bipolar) biasing of rotation around the long molecular axis as well as for a determination of the anisotropy in the fluctuations of this axis. The results show that the microscopic origin of the biquadratic coupling between the polarization and the tilt, which has been recently introduced into the extended Landau model of the SA-S*C transition, is the quadrupolar (or bipolar) rotational bias induced by the anisotropy in the fluctuations of the long molecular axis. The tilt induced anisotropy in the fluctuations is practically identical in chiral and non-chiral smectic C phases. 相似文献
73.
Nina Lah Ivan Leban Alenka Majcen Le Maréchal Vesna Ferk Philippe Le Grel Joachim Sieler 《Journal of chemical crystallography》2000,30(2):109-113
Two compounds have been prepared during the investigation of the reactivity of -halopyruvamides. The reaction products: 3-(4-chlorophenyl)imidazo[1,2-a]pyridine-2-carboxamide (1) and 7-carbamoyl-5-phenyl-2,3-dihydro[1,3]thiazolo[4,3-b][1,3]thiazol-4-ium chloride (2) were structurally characterized by x-ray crystallography. Compound 1 crystallizes in the orthorhombic space group Pca21 with a = 28.813(2), b = 9.369(1), and c = 9.361(1) Å. The structure contains two crystallographically different molecules. Compound 2 crystallizes in the monoclinic space group P21/c with the following cell parameters: a = 8.5895(8), b = 22.499(2), c = 7.4133(6) Å, and = 110.204(1)°. 相似文献
74.
Ivalina Trendafilova Manuel Ojeda John M. Andresen Alenka Risti Momtchil Dimitrov Nataa Novak Tuar Genoveva Atanasova Margarita Popova 《Molecules (Basel, Switzerland)》2023,28(1)
Transition metals as catalysts for total VOC oxidation at low temperatures (150–280 °C) are a big challenge nowadays. Therefore, iron-modified SBA-15, AlSBA-15, and ZrSBA-15 materials with 0.5 to 5.0 wt.% Fe loading were prepared and tested for toluene oxidation. It was found that increasing Fe loading significantly improved the rate of oxidation and lowered the temperature of achieving 100% removal of toluene from above 500 °C for the supports (AlSBA-15 and ZrSBA-15) to below 400 °C for 5FeZrSBA-15. The formation of finely dispersed iron oxide active sites with a particle size less than 5 nm was observed on all the SBA-15, AlSBA-15, and ZrSBA-15 supports. It was found that the surface properties of the mesoporous support due to the addition of Al or Zr predetermined the type of formed iron oxide species and their localization on the support surface. Fe-containing SBA-15 and AlSBA-15 showed activity in total toluene oxidation at higher temperatures (280–450 °C). However, 5 wt. % Fe-containing ZrSBA-15 showed excellent activity in the total oxidation of toluene as a model VOC at lower temperatures (150–380 °C) due to the synergistic effect of Fe-Zr and the presence of accessible and stable Fe2+/Fe3+ active sites. 相似文献
75.
Vrlinic T Debarnot D Mozetic M Vesel A Kovac J Coudreuse A Legeay G Poncin-Epaillard F 《Journal of colloid and interface science》2011,362(2):300-310
The surface grafting of multi-polymeric materials can be achieved by grafting as components such as polymers poly(N-isopropylacrylamide) and/or surfactant molecules (hexatrimethylammonium bromide, polyoxyethylene sorbitan monolaurate). The chosen grafting techniques, i.e. plasma activation followed by coating, allow a large spectrum of functional groups that can be inserted on the surface controlling the surface properties like adhesion, wettability and biocompatibility. The grafted polypropylene surfaces were characterized by contact angle analyses, XPS and AFM analyses. The influence of He plasma activation, of the coating parameters such as concentrations of the various reactive agents are discussed in terms of hydrophilic character, chemical composition and morphologic surface heterogeneity. The plasma pre-activation was shown inevitable for a permanent polymeric grafting. PNIPAM was grafted alone or with a mixture of the surfactant molecules. Depending on the individual proportion of each component, the grafted surfaces are shown homogeneous or composed of small domains of one component leading to a nano-structuration of the grafted surface. 相似文献
76.
Differential scanning calorimetry (DSC) was used to measure the decomposition rates of four commercially used initiators, 2,2′-azobis(isobutyronitrile) 2,2′-azobis(2,4-dimethylvaleronitrile), dilauroyl peroxide and bis(4-t-butylcyclohexyl)peroxydicarbonate, in dynamic mode, while the courses of methyl methacrylate polymerization with the listed initiators at 65, 75 and 85°C were measured isothermally. From the DSC curves, the polymerization enthalpies, the overall reaction rate constants and the activation energies for the initial steady-state polymerization were calculated. It was found that the polymerization enthalpy and the kinetic parameters depended on the type of the initiator. An initiator with a shorter decomposition half-lifetime shifted the onset of the gel effect to a higher conversion, intensified it and decreased the average molar mass of the polymer. 相似文献
77.
The study was initiated by the sudden uncontrolled release of airborne fluorides in 2005 into the environment from aluminium smelter factory that caused damage of vegetation. Samples of corn leaves and corn male flower heads with visible symptoms of fluoride intoxication had been collected in autumn 2005. Increased contents of total fluoride, which exceeded the maximum allowable content of fluorine in feeding stuffs, including meadow grass, were detected. During continuation of the study some commercially available herbal teas and plants used for preparing herbal teas infusions, collected in the field in 2010, were investigated to investigate possible uptake of fluoride from the soil. Nettle (Urtica dioica) has been found to be a promising passive bioindicator for monitoring phytotoxic effects of fluoride in the soil on the vegetation. Good correlation between labile free fluoride in the soil and total fluoride in the nettle has been found, while total fluoride in the soil, soil pH and the dominant wind direction were also proven as important factors influencing the uptake of fluoride by the nettle. 相似文献
78.
Renata Toplak Nina Lah Julija Volmajer Ivan Leban Alenka Majcen Le Marchal 《Acta Crystallographica. Section C, Structural Chemistry》2003,59(9):o502-o505
The reaction of different substituted α‐cyanooxiranes with thiourea resulted in the formation of the 2‐aminothiazolinone derivative 2‐amino‐5‐(2,5‐dimethoxyphenyl)‐1,3‐thiazol‐4(5H)‐one, C11H12N2O3S, (I), and the 2‐aminothiazole derivative ethyl 2‐amino‐5‐(2,5‐dimethoxyphenyl)‐1,3‐thiazole‐4‐carboxylate, C14H16N2O4S, (II). The geometries of the two crystallographically independent molecules in (II) are nearly identical but mirror related. The crystal structures of both compounds contain two types of intermolecular hydrogen bonds. 相似文献