全文获取类型
收费全文 | 82篇 |
免费 | 6篇 |
国内免费 | 2篇 |
专业分类
化学 | 63篇 |
晶体学 | 1篇 |
力学 | 1篇 |
数学 | 5篇 |
物理学 | 20篇 |
出版年
2023年 | 1篇 |
2022年 | 3篇 |
2021年 | 1篇 |
2020年 | 3篇 |
2019年 | 3篇 |
2018年 | 4篇 |
2017年 | 4篇 |
2016年 | 3篇 |
2015年 | 2篇 |
2014年 | 9篇 |
2013年 | 6篇 |
2012年 | 7篇 |
2011年 | 3篇 |
2010年 | 2篇 |
2009年 | 1篇 |
2008年 | 1篇 |
2007年 | 1篇 |
2005年 | 1篇 |
2004年 | 1篇 |
2003年 | 2篇 |
2000年 | 1篇 |
1998年 | 1篇 |
1996年 | 1篇 |
1995年 | 2篇 |
1994年 | 3篇 |
1992年 | 7篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1979年 | 2篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1972年 | 1篇 |
1966年 | 1篇 |
排序方式: 共有90条查询结果,搜索用时 15 毫秒
51.
A sensitive and simple HPLC method was developed for the simultaneous quantification of berberine and lysergol in rat plasma. The chromatographic separation was achieved on a C18 column using isocratic elution with methanol–acetonitrile–0.1% ortho‐phosphoric acid (25:20:55, v/v/v), pH adjusted to 6.5 with triethylamine and detected at a UV wavelength of 230 nm. The extraction of the berberine and lysergol from the rat plasma with methylene chloride resulted in their high recoveries (82.62 and 90.17%). HPLC calibration curves for both berberine and lysergol based on the extracts from the rat plasma were linear over a broad concentration range of 50–1000 ng/mL. The limit of quantification was 50 ng/mL. Intra‐ and inter‐day precisions were <15% and accuracy was 87.12–92.55% for berberine and 87.01–92.26% for lysergol. Stability studies showed that berberine and lysergol were stable in rat plasma for short‐ and long‐term period for sample preparation and analysis. The described method was successfully applied to study the pharmacokinetics of berberine as well as lysergol following oral administration in Sprague–Dawley rats. The results of the study inferred that lysergol improved the oral bioavailability of berberine. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
52.
J. Bhattacharya N. Chakravarty S. Pattnaik W.D. Slafer R. Biswas V. Dalal 《Journal of Non》2012,358(17):2313-2318
Light trapping is essential to harvest long-wavelength red and near-infrared photons in thin film silicon solar cells. Light trapping in p-i-n thin film cells is commonly achieved with back-reflectors, and in n-i-p cells with textured front transparent conductors. We systematically compare the optical properties and performance of randomly roughened back reflectors with periodic plasmonic-photonic back-reflectors in p-i-n solar cells. The randomly textured back reflectors were prepared to have very high diffuse reflectance comparable to the state of the art. The periodic back reflectors of tapered nano-pillars/bumps show enhanced quantum efficiency and optical absorption over randomly structured back reflectors using the same solar cell architecture in nc-Si solar cells. The strong diffraction and light concentration in periodic back reflectors may be more beneficial than the light scattering offered by randomly textured back reflectors. 相似文献
53.
Applying the known procedure for synthesis of alkali metal ozonides, just at a lower temperature, has yielded a new polymorph of rubidium ozonide, α‐RbO3 [P21; a = 436.3(2), b = 595.3(3), c = 548.7(3) pm, β = 99.680(7), R = 0.0400, 1184 reflections]. Like previously reported β‐RbO3, the basic structural arrangement of anions and cations corresponds to the CsCl type of structure, however, the mutual orientation of the ozonide ions is different, in as much as one of the two terminal oxygen atoms is pointing to the adjacent bridging oxygen atom, forming a chain running along the b axis. 相似文献
54.
Shrikant Modak V. Guru Krishna Kumar Sharad Gupta 《Journal of Dispersion Science and Technology》2017,38(9):1266-1275
We study the influence of phosphorylation on the foamability and stability of bovine serum albumin (BSA), phosphorylated BSA (pBSA), and citrus peel pectin (CPP) mixed foams as a function of BSA–CPP, pBSA–CPP mixing ratios, at a fixed solution pH of 4.5. Our results show that pBSA solutions result in more stable foams as compared with their BSA counterparts. We further show that the addition of CPP leads to BSA–CPP and pBSA–CPP complexation which increases the foamability and stability of foams as compared with protein-only foams. Also, foam stability is highest for pBSA–CPP mixed foams with mixing ratio pBSA:CPP?=?1:1 due to the combined effect of pBSA–pBSA and pBSA–CPP interactions. 相似文献
55.
Kantak JB Bagade AV Mahajan SA Pawar SP Shouche YS Prabhune AA 《Applied biochemistry and biotechnology》2011,164(7):969-978
A lipolytic mesophilic fungus which produces lipase extracellularly was isolated from soil. Based on ITS1-5.8S–ITS4 region
sequences of ribosomal RNA, it was concluded that the isolate JK-1 belongs to genus Rhizopus and clades with Rhizopus oryzae. The present paper reports the screening, isolation, identification, and optimization of fermentation conditions for the
production of lipase (EC 3.1.1.3). Culture conditions were optimized, and the highest lipase production was observed in basal
medium with corn steep liquor as nitrogen source and glucose as carbon source. Maximum lipase production was observed at 72 h,
which is about 870 U/ml. Optimization of fermentation conditions resulted in 16-fold enhancement in enzyme production. 相似文献
56.
Dr. Shrikant Bhat Dr. Leonore Wiehl Shariq Haseen Prof. Dr. Peter Kroll Dr. Konstantin Glazyrin Philipp Gollé-Leidreiter Prof. Dr. Ute Kolb Dr. Robert Farla Dr. Jo-Chi Tseng Dr. Emanuel Ionescu Prof. Dr. Tomoo Katsura Prof. Dr. Ralf Riedel 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(10):2187-2194
We report the first oxynitride of tin, Sn2N2O (SNO), exhibiting a Rh2S3-type crystal structure with space group Pbcn. All Sn atoms are in six-fold coordination, in contrast to Si in silicon oxynitride (Si2N2O) and Ge in the isostructural germanium oxynitride (Ge2N2O), which appear in four-fold coordination. SNO was synthesized at 20 GPa and 1200–1500 °C in a large volume press. The recovered samples were characterized by synchrotron powder X-ray diffraction and single-crystal electron diffraction in the TEM using the automated diffraction tomography (ADT) technique. The isothermal bulk modulus was determined as Bo=193(5) GPa by using in-situ synchrotron X-ray diffraction in a diamond anvil cell. The structure model is supported by DFT calculations. The enthalpy of formation, the bulk modulus, and the band structure have been calculated. 相似文献
57.
新的聚苯乙烯负载锌化合物:高效苯酚氧化催化剂(英文) 总被引:1,自引:0,他引:1
Alekha Kumar Sutar Yasobanta Das Sasmita Pattnaik Anita Routaray Nibedita Nath Prasanta Rath Tungabidya Maharana 《催化学报》2014,35(10):1701-1708
The novel recyclable free –ONNO– tetradentate Schiff base ligand N,N′‐bis(2‐hydroxy‐3‐ methox‐ybenzaldehyde)4‐methylbenzene‐1,2‐diamine (3‐MOBdMBn) was synthesized. Complexation of this ligand with zinc(3‐MOBdMBn‐Zn) was performed, and the catalytic activity of the complex was evaluated. The polymer‐supported analog of this complex(P‐3‐MOBdMBn‐Zn) was synthesized, and its catalytic activity was studied. These free and polymer‐anchored zinc complexes were prepared by the reactions of metal solutions with one molar equivalent of unsupported 3‐MOBdMBn or P‐3‐MOBdMBn in methanol under nitrogen. The catalytic activity of 3‐MOBdMBn‐Zn and P‐3‐MOBdMBn‐Zn was evaluated in phenol oxidation. The activity of P‐3‐MOBdMBn‐Zn was signif‐icantly affected by the polymer support, and the rate of phenol conversion was around 50% for polystyrene‐supported 3‐MOBdMBn. The experimental results indicated that the reaction rate was affected by the polymer support, and the rate of phenol conversion was 1.64 μmol/(L·s) in the presence of polystyrene‐supported 3‐MOBdMBn. 相似文献
58.
Ashok P. Acharya Rahul D. Kamble Snehalkumar D. Patil Shrikant V. Hese Omprakash S. Yemul Sudhakar G. Patil Shivshankar N. Halale Bhaskar S. Dawane 《Chemical Papers》2014,68(5):719-724
A novel series of indeno-benzothiazepine derivatives was synthesised via a “green” route. Synthesis of these compounds involves the treatment of dinucleophiles such as 2-aminobenzenethiols with α,β-unsaturated ketones in poly(oxyethylene) (poly(ethylene glycol), PEG-400) catalysed by acetic acid. The synthone α,β-unsaturated ketones were obtained by Claisen-Schmidt condensation of indan-1-one with substituted pyrazole-2-carbaldehydes prompted by bleaching earth (pH 12.5) as catalyst and PEG-400 as “green” reaction solvent. Screening of all the synthesised compounds for antimicrobial activity revealed that most of these compounds exhibited moderate to significant antimicrobial activity. 相似文献
59.
Arun K. Roy Samuel Pattnaik Rajani K. Samal Padma L. Nayak 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(8):1241-1249
The polymerization of acrylonitrile initiated by the redox system K2S2O8-citric acid catalyzed by Ag+ ion has been studied over the temperature range 35–50°C. The rate of polymerization is proportional to the square root of peroxydisulfate concentration. The initial rate increases with increasing citric acid concentration, but at relatively higher concentration of citric acid the rate decreases. The rate of polymerization also increases with increasing monomer concentration and temperature. The overall activation energy calculated from the Arrhenius plot was found to be 4.6 kcal/mole. On the basis of the observation, a suitable kinetic scheme has been proposed for the reaction. 相似文献
60.
Important results of a numerical study performed on combined conduction–mixed convection–surface radiation from a vertical channel equipped with three identical flush-mounted discrete heat sources in its left wall are provided here. The channel has walls of identical height with the spacing varied by varying its aspect ratio (AR). The cooling medium is air that is considered to be radiatively transparent. The heat generated in the channel gets conducted along its walls before getting dissipated by mixed convection and radiation. The governing equations for fluid flow and heat transfer are considered without boundary layer approximations and are transformed into vorticity–stream function form and are later normalized. The resulting equations are solved, along with relevant boundary conditions, making use of the finite volume method. The computer code written for the purpose is validated both for fluid flow and heat transfer results with those available in the literature. Detailed parametric studies have been performed and the effects of modified Richardson number, surface emissivity, thermal conductivity and AR on various pertinent results have been looked into. The significance of radiation in various regimes of mixed convection has been elucidated. The relative contributions of mixed convection and radiation in carrying the mandated cooling load have been thoroughly explored. 相似文献