全文获取类型
收费全文 | 181篇 |
免费 | 9篇 |
专业分类
化学 | 118篇 |
晶体学 | 1篇 |
力学 | 2篇 |
数学 | 13篇 |
物理学 | 56篇 |
出版年
2023年 | 1篇 |
2022年 | 4篇 |
2021年 | 3篇 |
2020年 | 9篇 |
2019年 | 6篇 |
2018年 | 5篇 |
2017年 | 1篇 |
2016年 | 6篇 |
2015年 | 3篇 |
2014年 | 10篇 |
2013年 | 11篇 |
2012年 | 15篇 |
2011年 | 21篇 |
2010年 | 6篇 |
2009年 | 11篇 |
2008年 | 6篇 |
2007年 | 6篇 |
2006年 | 10篇 |
2005年 | 9篇 |
2004年 | 8篇 |
2003年 | 8篇 |
2002年 | 5篇 |
2001年 | 3篇 |
2000年 | 8篇 |
1999年 | 1篇 |
1997年 | 1篇 |
1996年 | 3篇 |
1995年 | 3篇 |
1994年 | 2篇 |
1993年 | 1篇 |
1992年 | 4篇 |
排序方式: 共有190条查询结果,搜索用时 46 毫秒
81.
Fluorescent Detection of 2,4‐DNT and 2,4,6‐TNT in Aqueous Media by Using Simple Water‐Soluble Pyrene Derivatives 下载免费PDF全文
Dr. Igor S. Kovalev Olga S. Taniya Nataliya V. Slovesnova Grigory A. Kim Dr. Sougata Santra Prof. Grigory V. Zyryanov Dr. Dmitry S. Kopchuk Prof. Adinath Majee Prof. Valery N. Charushin Prof. Oleg N. Chupakhin 《化学:亚洲杂志》2016,11(5):775-781
Pyrene‐containing water‐soluble probes for the fluorescent detection of nitroaromatic compounds (NACs), such as explosive components (2,4‐DNT and 2,4,6‐TNT) and herbicides (2,4‐dinitrocresol, 2,4‐DNOC), in aqueous media are reported. In the probes, the introduction of surface‐active hydrophilic “heads” at the periphery of lipophilic (i.e., hydrophobic) pyrene “tails” resulted in the formation of highly fluorescent micelle‐like aggregates/pre‐associates in aqueous solutions at concentrations of ≤10?5 m . The enhanced fluorescence quenching of the herein reported architectures is achieved in the presence of ultra‐trace amounts of TNT or 2,4‐DNT with values of Stern–Volmer quenching constant close to 1×105 m ?1 and a detection limit as low as 182 ppb. The most hydrophilic probes demonstrated higher response to 2,4‐DNT over TNT. Filter paper test strips impregnated with 1×10?5 m solutions of the probes were able to detect TNT, 2,4‐DNT, and other NACs at levels as low as 50 ppb in water. 相似文献
82.
83.
84.
Adinath Majee Shrishnu Kumar KunduSougata Santra Alakananda Hajra 《Tetrahedron letters》2012,53(33):4433-4435
A new method for oxidation of alcohols to carbonyl compounds has been developed using NH2OH·HCl and NaIO4 under mild reaction conditions at room temperature. Application of the method for the synthesis of diiodo compound from α,β-unsaturated carbonyl compound is also described. 相似文献
85.
The white rot fungus Phanerochaete chrysosporium has been identified to be an environmentally useful microorganism for the degradation of various hazardous pollutants, mainly because of its ligninolytic enzyme system, particularly the lignin peroxidase (LiP) secreted by the fungus. In the present work, the behavior of the fungus in liquid medium due to variation in physico-chemical parameters, i.e., glucose concentration, nitrogen concentration, agitation, etc., was studied. Increment of the initial concentration of glucose in the medium increases the biomass growth and LiP activity, when cultured under controlled conditions. The biomass growth and LiP activity by the fungus was modeled following stochastic approach. The behavior of growth and enzyme activity of the fungus observed from the model were found to be in agreement with the experiments qualitatively. 相似文献
86.
Roger T Büscher J Bastin B Kirsebom OS Raabe R Alcorta M Äystö J Borge MJ Carmona-Gallardo M Cocolios TE Cruz J Dendooven P Fraile LM Fynbo HO Galaviz D Gasques LR Giri GS Huyse M Hyldegaard S Jungmann K Kruithof WL Lantz M Perea A Riisager K Saastamoinen A Santra B Shidling PD Sohani M Sørensen AJ Tengblad O Traykov E van der Hoek DJ Van Duppen P Versolato OO Wilschut HW 《Physical review letters》2012,108(16):162502
A measurement of the final state distribution of the (8)B β decay, obtained by implanting a (8)B beam in a double-sided silicon strip detector, is reported here. The present spectrum is consistent with a recent independent precise measurement performed by our collaboration at the IGISOL facility, Jyv?skyl? [O. S. Kirsebom et al., Phys. Rev. C 83, 065802 (2011)]. It shows discrepancies with previously measured spectra, leading to differences in the derived neutrino spectrum. Thanks to a low detection threshold, the neutrino spectrum is for the first time directly extracted from the measured final state distribution, thus avoiding the uncertainties related to the extrapolation of R-matrix fits. Combined with the IGISOL data, this leads to an improvement of the overall errors and the extension of the neutrino spectrum at high energy. The new unperturbed neutrino spectrum represents a benchmark for future measurements of the solar neutrino flux as a function of energy. 相似文献
87.
The cysteine residues of yeast alcohol dehydrogenase (YADH) were covalently modified by N-(1-pyrenyl) maleimide (PM). A maximum of 3.4 cysteines per YADH monomer could be modified by PM. The secondary structure of PM-YADH was found to be similar to that of the native YADH using far-UV circular dichroism. The covalent modification of YADH by PM inhibited the enzymatic activity indicating that the active site of the enzyme was altered. PM-YADH displayed maximum excimer fluorescence at an incorporation ratio of 2.6 mol of PM per monomeric subunit of YADH. Nucleotide adenine dinucleotide (NAD) divalent zinc and ethanol reduced the excimer fluorescence of PM-YADH indicating that these agents induce conformational changes in the enzyme. Guanidinium hydrochloride (GdnHCl)-induced unfolding of YADH was analyzed using tryptophan fluorescence, pyrene excimer fluorescence and enzymatic activity. The unfolding of YADH was found to occur in a stepwise manner. The loss of enzymatic activity preceded the global unfolding of the protein. Further, changes in tryptophan fluorescence with increasing GdnHCl suggested that YADH was completely unfolded by 2.5 M GdnHCl. Interestingly, residual structures of YADH were detected even in the presence of 5 M GdnHCl using the excimer fluorescence of PM-YADH. 相似文献
88.
A recent environmental survey has listed Kolkata, a megacity in Eastern India, as one of the most polluted cities in the world. Rapid urbanization and industrialization have resulted in an alarming increase in the level of air pollution in the city. Epiphytic lichens have extensively been used worldwide as bioindicators of environmental quality. They are very responsive to environmental stressors, especially gaseous pollutants and particulates including trace elements and heavy metals. This work describes application of energy dispersive X‐ray fluorescence, a fast multi‐elemental analytical technique, for estimating concentration of trace elements of lichen samples collected from sites in and around Kolkata. The results indicate that the samples from sites burdened with heavy vehicular load together with pollution from various industries and factories have significantly higher concentration of elements such as S, Ca, V, Cr, Mn, Fe, Ni and Pb as compared to those collected from sites having less or no load. Remarkable seasonal variation is also noted in the concentration of the elements such as Mn, Fe, Cu, Zn and Pb. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
89.
Prasanta Kumar Santra Ramkrishna Roy Chittaranjan Sinha 《Journal of Chemical Sciences》2000,112(5):523-534
2-(Arylazo)pyrimidines (aapm) are N,N′-chelating ligands and synthesise orange-red complexes of composition [Pd(aapm)Cl2],1, with Pd(MeCN)2Cl2 in MeCN. The complex hascis-PdCl2 configuration [v(Pd-Cl): 340, 360 cm−1]. The treatment of Tollen’s reagent (‘AgOH’) leads to chelatative hydroxylation in the pendant aryl ring, affording a green
phenolato complex, Pd(aapmO)Cl,5 (aapmO is deprotonated 2-((8-hydroxo)arylazo)pyrimidine). The reaction is also carried out by controlled addition of dilute
sodium hydroxide in air or by the addition of PhIO/m-chloroperbenzoic acid to a MeCN suspension of the complex. A single Pd-Cl stretch at 360 cm−1 supports the composition of phenolato complex. Unlike Pd(aapm)Cl2 the hydroxylated product, Pd(aapmO)Cl, has a structured intense absorption in the visible region near 670 nm. The Pd-Cl bond
in Pd(aapmO)Cl is highly sensitive to nucleophilic substitution and slowly hydrolyses in aqueous medium.
For Parts I and II, see references 16 and 17; for Part III,Synth. React. Inorg. Met.- Org. Chem. (in press) 相似文献
90.
Singh Shashank Oswal Mumtaz Behera B. R. Kumar Ashok Santra S. Acharya R. Singh K. P. 《Journal of Radioanalytical and Nuclear Chemistry》2020,323(3):1443-1449
Journal of Radioanalytical and Nuclear Chemistry - Elemental concentrations namely P, S, Cl, K, Ca, Sc, Ti, Mn, Fe, Cu, Zn, Rb, Br and Sr were determined using Particle Induced X-ray Emission... 相似文献