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51.
The effect of 1-alkyl-4-methylpyridinium based ionic liquids on the conductivity behavior of l(+)-lactic acid (LaH) was studied in Poly(ethylene glycol) (PEG) aqueous solutions. The molar conductivities of LaH in the aqueous solutions of PEG, (PEG + 1-hexyl-4-methylpyridinium bromide) and (PEG + 1-octyl-4-methylpyridinium bromide) were measured over the temperature ranges of 288.15–318.15 K. The molar conductivity data were analyzed by applying the Quint–Viallard (QV) conductivity equation to determine the limiting molar conductivities (Λ 0) and dissociation constants (\( K_{\text{D}} \)). The results show that the values of limiting molar conductivity increased as the temperature increased, which indicates that the dissociation process is endothermic. The \( K_{\text{D}} \) values were also used to calculate the dissociation standard thermodynamic functions (\( \Delta G_{\text{D}}^{0} \), \( \Delta S_{\text{D}}^{0} \) and \( \Delta H_{\text{D}}^{0} \)). The results revealed that the dissociation process of LaH is controlled by entropy at all temperatures. 相似文献
52.
Mehrdad Khatami Iraj Sharifi Marcos A. L. Nobre Niloofar Zafarnia 《Green Chemistry Letters and Reviews》2018,11(2):125-134
Grass waste was used for transform an inexpensive waste into health. Silver nanoparticles (AgNPs) have been synthesized using waste material (dried grass). The average size of silver nanoparticles observed in transmission electron images was estimated to be about 15?nm. The anticancer, antifungal and antibacterial effect of AgNPs were studied in vitro. The minimum inhibitory concentration of AgNPs against Pseudomonas aeruginosa and Acinetobacter baumannii was calculated about 3?µg/ml. The highest level of inhibitory effect of AgNPs against Fusarium solani was close to 90% at a concentration of 20?μg/ml of AgNPs. An inhibitory effect on the cancer cell growth is reach, by increasing the concentration of AgNPs to 5?µg/ml; the cancer cells’ survival decreases about 30%. Western results showed that the expression of Cyclin D1 protein of MCF-7 cell line decreased after treatment with the effective concentration of AgNPs. 相似文献
53.
Biuck Habibi Shiva Rostamkhani Mehrdad Hamidi 《Journal of the Iranian Chemical Society》2018,15(7):1569-1580
A simple, sensitive and accessible while reliable method was developed and validated for quantitation of buprenorphine (Bup) as a highly lipophilic drug in human urine samples. The proposed method is based on a rapid and easy dispersive micro solid-phase extraction procedure using magnetic molecularly imprinted polymer nanoparticles (MMIPNPs), magnetite (Fe3O4) cores surrounded by polyamidoamine and Bup as template, followed by high-performance liquid chromatographic analysis with fluorescence detector (HPLC-FL). The prepared MMIPNP adsorbent was characterized by different techniques. Transmission electron microscopy images show that the Fe3O4 core nanoparticles are well enwrapped by MIP layers. In determination process, Bup could be quantitatively extracted using MMIPNPs and then can be easily desorbed by mixture of sodium hydroxide (0.1 mol/L) and methanol (1:9, v/v) solution before injection to HPLC. The relative recoveries of Bup were found to be 97.4–100.3%, and the linear dynamic range was within the ranges of 1–1000 ng/mL with R2 of 0.9998. Remarkably high quality of 0.21 and 0.71 ng/mL was obtained as the limit of detection and limit of quantification, respectively. The developed method was successfully applied for determination of Bup in infected human urine samples. 相似文献
54.
A series of terpolymers containing silyl pendant groups were prepared by free radical cross‐linking copolymerization. Et3Si and HMe2Si were covalently linked with 4‐vinylbenzyl and abbreviated as TESiMSt and DMSiMSt, respectively. Et3Si was covalently linked with 2‐hydroxyethyl methacrylate (HEMA). The silyl‐linked HEMA are abbreviated as TESiEMA. Free radical terpolymerization of the methacrylic acid (MAA) with different molar ratios of organosilyl monomers was carried out at 60–70 °C. The compositions of the polymers were determined by FT‐IR spectroscopy and 1H‐NMR. The glass transition temperature (Tg) of the polymers was determined calorimetrically. The study of DSC curves showed that incorporation of monomers with cyclic units in polymer chains increases the rigidity of terpolymers and the Tg value is subsequently increased. 相似文献
55.
Daneshvar P Yazdanpanah M Cuthbert C Cole DE 《Rapid communications in mass spectrometry : RCM》2003,17(4):358-362
Enzymatic cyclization of homocysteine forms a reactive thiolactone that may play an important role in its cardiovascular toxicity, but reliable quantitation of the free thiolactone metabolite in physiological fluids has not been reported. We have therefore used a highly selective gas chromatography/mass spectrometry (GC/MS) technique combined with the sensitivity of negative chemical ionization (NCI) to develop a quantitative method for the detection of homocysteine thiolactone (HcyTL) in plasma. To improve accuracy the deuterated isomer d(4)-HcyTL was synthesized and added to plasma as internal standard. The plasma was then treated with silica solid-phase extraction and derivatized with heptafluorobutyric anhydride. The derivative was analyzed by GC/MS in NCI mode with methane as the reagent gas and quantified by analyzing for the HcyTL ion [M(-)[bond]HF] and its d(4)-HcyTL counterpart in single-ion monitoring mode. The calibration curve showed a dynamic linear range up to 40 nmol/L. Within-day precision (n = 20, nominal concentration 5.2 nmol/L) was 0.96% and between-day precision was 3.9%, with a detection limit of 1.7 nmol/L and quantification limit of 5.2 nmol/L. Two human plasma samples had HcyTL concentrations of 18 and 25 nmol/L. This facile method for quantitation of homocysteine thiolactone opens the way for more detailed clinical studies of its potential role in homocysteine-induced arteriosclerosis and vaso-occlusive disease. 相似文献
56.
Effect of nano‐modified SiO2/Al2O3 mixed‐matrix micro‐composite fillers on thermal,mechanical, and tribological properties of epoxy polymers 下载免费PDF全文
Sadasivan S. Vaisakh Abdul Azeez Peer Mohammed Mehrdad Hassanzadeh Jean F. Tortorici Renaud Metz Solaiappan Ananthakumar 《先进技术聚合物》2016,27(7):905-914
Thermo‐mechanically durable industrial polymer nanocomposites have great demand as structural components. In this work, highly competent filler design is processed via nano‐modified of micronic SiO2/Al2O3 particulate ceramics and studied its influence on the rheology, glass transition temperature, composite microstructure, thermal conductivity, mechanical strength, micro hardness, and tribology properties. Composites were fabricated with different proportions of nano‐modified micro‐composite fillers in epoxy matrix at as much possible filler loadings. Results revealed that nano‐modified SiO2/Al2O3 micro‐composite fillers enhanced inter‐particle network and offer benefits like homogeneous microstructures and increased thermal conductivity. Epoxy composites attained thermal conductivity of 0.8 W/mK at 46% filler loading. Mechanical strength and bulk hardness were reached to higher values on the incorporation of nano‐modified fillers. Tribology study revealed an increased specific wear rate and decreased friction coefficient in such fillers. The study is significant in a way that the design of nano‐modified mixed‐matrix micro‐composite fillers are effective where a high loading is much easier, which is critical for achieving desired thermal and mechanical properties for any engineering applications. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
57.
In this paper we use a modified form of the mixture theory developed by Massoudi and Rajagopal to study the blood flow in a simple geometry, namely flow between two plates. The blood is assumed to behave as a two-component mixture comprised of plasma and red blood cells (RBCs). The plasma is assumed to behave as a viscous fluid whereas the RBCs are given a granular-like structure where the viscosity also depends on the shear-rate. 相似文献
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60.
Fereshteh Akbari Mehrdad Ghaznavi Esmaile Khorram 《Journal of Optimization Theory and Applications》2018,178(2):560-590
The presented study deals with the scalarization techniques for solving multiobjective optimization problems. The Pascoletti–Serafini scalarization technique is considered, and it is attempted to sidestep two weaknesses of this method, namely the inflexibility of the constraints and the difficulties of checking proper efficiency. To this end, two modifications for the Pascoletti–Serafini scalarization technique are proposed. First, by including surplus variables in the constraints and penalizing the violations in the objective function, the inflexibility of the constraints is resolved. Moreover, by including slack variables in the constraints, easy-to-check statements on proper efficiency are obtained. Thereafter, the two proposed modifications are combined to obtain the revised Pascoletti–Serafini scalarization method. Theorems are provided on the relation of (weakly, properly) efficient solutions of the multiobjective optimization problem and optimal solutions of the proposed scalarized problems. All the provided results are established with no convexity assumption. Moreover, the capability of the proposed approaches is demonstrated through numerical examples. 相似文献