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51.
In this Note we establish a Hölder stability estimate for an inverse pointwise source elliptic problem. 相似文献
52.
Abdellatif Mamanou Fethi Khelfaoui Kamel Edinne Aiadi 《Optical and Quantum Electronics》2014,46(1):235-245
In this paper, a number of polymeric waveguide structures have been analyzed by using two distinct techniques which are: effective index method (EIM) and numerical simulation based on finite difference method (FDM). The main aim of this investigation is the calculation of effective indexes (EI) of the following structures: rib, ridge and buried channel waveguides at telecom wavelength $\lambda =1.55\,\upmu \hbox {m}$ for different dimensions of waveguide cores varying from 1.5–4 $\upmu \hbox {m}$ . Moreover, other optical propagation characteristics such as: confinement factor, normalized and propagation constant have been studied in TE polarisation. Otherwise the effect of the structure parameters and dimensions on the dispersion characteristics has been investigated. On the other hand, the optical field distribution has been computed using commercial software named OlympIOs. The polymers applied in the design of waveguide structures are the PVCi (n = 1,562 $\lambda = {1.55}\,\upmu $ m) used as core layer and the PMATRIFE (n = 1,409 $\lambda = 1.55\,\upmu $ m) used as substrate or cladding layer. The results obtained using EIM and simulation based on FDM show that effective index and field confinement factor of TE fundamental mode increase monotonously with the increasing dimension of core. The obtained results are in good agreement with published data based on other numerical methods. 相似文献
53.
Touahir L Galopin E Boukherroub R Gouget-Laemmel AC Chazalviel JN Ozanam F Saison O Akjouj A Pennec Y Djafari-Rouhani B Szunerits S 《The Analyst》2011,136(9):1859-1866
The use of an amorphous silicon-carbon alloy overcoating on silver nanostructures in a localized surface plasmon resonance (LSPR) sensing platform allows for decreasing the detection limit by an order of magnitude as compared to sensors based on gold nanostructures deposited on glass. In addition, silver based multilayer structures show a distinct plasmonic behaviour as compared to gold based nanostructures, which provides the sensor with an increased short-range sensitivity and a decreased long-range sensitivity. 相似文献
54.
Selectfluor and NFSI exo‐Glycal Fluorination Strategies Applied to the Enhancement of the Binding Affinity of Galactofuranosyltransferase GlfT2 Inhibitors 下载免费PDF全文
Dr. Lidia Dumitrescu Dr. Guillaume Eppe Abdellatif Tikad Dr. Weidong Pan Sandy El Bkassiny Sudagar S. Gurcha Dr. Ana Ardá Prof. Jesús Jiménez‐Barbero Prof. Gurdyal S. Besra Prof. Stéphane P. Vincent 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(46):15208-15215
Two complementary methods for the synthesis of fluorinated exo‐glycals have been developed, for which previously no general reaction had been available. First, a Selectfluor‐mediated fluorination was optimized after detailed analysis of all the reaction parameters. A dramatic effect of molecular sieves on the course of the reaction was observed. The reaction was generalized with a set of biologically relevant furanosides and pyranosides. A second direct approach involving carbanionic chemistry and the use of N‐fluorobenzenesulfonimide (NFSI) was performed and this method gave better diastereoselectivities. Assignment of the Z/E configuration of all the fluorinated exo‐glycals was achieved based on the results of HOESY experiments. Furthermore, fluorinated exo‐glycal analogues of UDP‐galactofuranose were prepared and assayed against GlfT2, which is a key enzyme involved in the cell‐wall biosynthesis of major pathogens. The fluorinated exo‐glycals proved to be potent inhibitors as compared with a series of C‐glycosidic analogues of UDP‐Galf, thus demonstrating the double beneficial effect of the exocyclic enol ether functionality and the fluorine atom. 相似文献
55.
Abdulmajeed A. AbuDujayn Abdellatif A. Mohamed Mohamed Saleh Alamri Shahzad Hussain Mohamed A. Ibraheem Akram A. Abdo Qasem Ghalia Shamlan Nashi K. Alqahtani 《Molecules (Basel, Switzerland)》2023,28(1)
The effectiveness of hydrocolloids (2% maximum in various combinations) from various sources, including maltodextrins (MD) with polymerization degree (DP) 18 and ziziphus gum (ZG), on the dough properties and quality of panned bread, as well as the possibility of using them to delay the bread staling process, have been investigated after 24, 72, and 96 h of storage. By evaluating the pasting capabilities of wheat flour slurry, dough properties, and the final product, the effects of the ziziphus gum (ZG) and maltodextrins (MD) were ascertained. A TA-TXT texture analyzer, a texture profile analysis test, and Micro-doughLab were used to evaluate the dough mixing properties. Additionally, a hedonic sensory evaluation of the overall acceptance of the bread, as well as its texture, aroma, taste, and color, was done. It is clear that MD had a more distinct impact than ZG on the way dough was mixed, the texture of the gel, and the finished product. The combination of MD and ZG significantly altered the bread’s physical characteristics and its aging over time. The decreased peak viscosity and noticeably smaller setback of wheat flour gels, which corresponded to lower gel hardness, serve as evidence of reduced amylose retrogradation. At 2%, MD outperformed ZG in terms of increasing water absorption, dough stability, and bread loaf volume. With the exception of the blend that included three times as much MD as ZG, all mixes, including the control, exhibited an increase in bread firmness as a function of time after storage. Overall, the panelists liked (score of 5 and above) the bread made with mixes that had either MD or ZG, or a combination of both. 相似文献
56.
57.
Lutterman DA Chouai A Liu Y Sun Y Stewart CD Dunbar KR Turro C 《Journal of the American Chemical Society》2008,130(4):1163-1170
The DNA light-switch complex [Ru(bpy)2(tpphz)]2+ (1, bpy = 2,2'-bipyridine, tpphz = tetrapyrido[3,2-a:2',3'-c:3',2'-h:2',3'-j]phenazine) is luminescent when bound to DNA and in organic solvents and weakly emissive in water. To date, light-switch behavior by transition metal complexes has generally been regarded as confirmation of DNA intercalation. In contrast, the present work demonstrates that the nonintercalating bimetallic complex [(bpy)2Ru(tpphz)Ru(bpy)2]4+ (2) behaves as a DNA light-switch. Weak emission from the 3MLCT excited state of 2 is observed in water with lambda(em) = 623 nm (phi(em) = 1.4 x 10(-4)), and a red shift (lambda(em) = 702 nm) and 40-fold increase in intensity are observed upon addition of 100 microM calf thymus DNA (ct-DNA). Addition of increasing concentrations of 2 to 1 mM herring sperm DNA does not result in an increase in the viscosity of the solution, indicating that the complex is not an intercalator. Additionally, experiments were conducted to ensure that the emission enhancement did not arise from threading intercalation of the complex. The in situ generation of 2 intercalated between the base pairs of ct-DNA in a threading fashion, however, exhibits emission maximum at 685 nm, which is blue-shifted from that of surface-bound 2. DFT calculations show low-lying orbitals in 2 that are expected to exhibit nonemissive character when contributing to the MLCT state, in accord with the lower emission intensity observed for 2 relative to that for 1. To our knowledge, the present work is the first example of a nonintercalating light-switch metal complex, thus showing that light-switch behavior cannot be used exclusively as confirmation of intercalation. 相似文献
58.
This work presents a novel disposable electrochemical sensor for paracetamol (PCM). The sensing platform is based on graphene, manufactured via laser-scribing technology (LSG) to produce a 3D-porous structure that offers a large surface area. The analytical performances of LSG electrodes were greatly enhanced due to the high catalytic activity of graphene produced by LSG technology compared to conventional carbon electrodes. Moreover, the results showed an outstanding adsorption feature towards PCM, allowing its detection at nanomolar level from 5 nM to 100 nM through pre-concentration. The proposed sensing strategy was successfully applied for the determination of PCM in human urine samples. 相似文献
59.
Khaled R. A. Abdellatif Morshed A. Chowdhury Edward E. Knaus 《Journal of heterocyclic chemistry》2008,45(6):1707-1710
A regiospecific cyclization‐dehydration reaction of a 1‐[(4‐(N‐alkyl‐N‐(tert‐butyloxycarbony)amino)‐phenyl]‐4,4,4‐trifluorobutane‐1,3‐done with a 4‐aminosulfonyl‐, or 4‐methylsulfonyl‐, phenylhydrazine hydrochloride in refluxing ethanol proceeded with simultaneous loss of the N‐tert‐butyloxycarbonyl protecting group to afford a group of 1‐(4‐methanesulfonylphenyl or 4‐aminosulfonylphenyl)‐5‐[4‐(N‐alkylaminophenyl)]‐3‐(trifluoromethyl)‐11H‐pyrazoles(6). Subsequent reaction of the pyrazole 6 (R1 = R2 = Me) with nitric oxide (40 psi) proceeded via a N‐methylamino‐N‐diazen‐1‐ium‐1,2‐diolate intermediate that undergoes protonation of the more basic diazen‐1‐ium‐1,2‐diolate N2‐nitrogen and then loss of a nitroxyl (HNO) species to furnish the N‐nitroso product 7. 相似文献
60.
Salma Trady Abdellatif Hasnaoui M’hammed Mazroui Khalid Saadouni 《The European Physical Journal B - Condensed Matter and Complex Systems》2016,89(10):223
In this study we examine the structural properties of single-component metallic glasses of aluminum. We use a molecular dynamics simulation based on semi-empirical many-body potential, derived from the embedded atom method (EAM). The radial distribution function (RDF), common neighbors analysis method (CNA), coordination number analysis (CN) and Voronoi tessellation are used to characterize the metal’s local structure during the heating and cooling (quenching). The simulation results reveal that the melting temperature depends on the heating rate. In addition, atomic visualization shows that the structure of aluminum after fast quenching is in a glassy state, confirmed quantitatively by the splitting of the second peak of the radial distribution function, and by the appearance of icosahedral clusters observed via CNA technique. On the other hand, the Wendt-Abraham parameters are calculated to determine the glass transition temperature (Tg), which depends strongly on the cooling rate; it increases while the cooling rate increases. On the basis of CN analysis and Voronoi tessellation, we demonstrate that the transition from the Al liquid to glassy state is mainly due to the formation of distorted and perfect icosahedral clusters. 相似文献