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461.
Finite capacity assembly-like queues 总被引:1,自引:0,他引:1
U. Narayan Bhat 《Queueing Systems》1986,1(1):85-101
In assembly lines, service involves assembling units coming from more than one source. In queue terminology, we may consider this situation as one in which service is rendered only to groups of customers — one from each class. In this paper we give procedures to determine response time characteristics of such a system under Markovian assumptions when a finite capacity restriction is imposed. This restriction is imposed to reflect reality as well as to make analysis tractable. In the course of this study, we also give a recursive technique to determine the distribution of the time taken for a specific number of departures in a Poisson queue from an arbitrary initial state. We demonstrate that this distribution is related to the response time distribution of the assembly-like queue. We believe that this procedure will also be of independent interest. 相似文献
462.
Ramesh Narayan 《Pramana》1979,13(5):559-570
Ionic radii and compressibilities have been calculated for a number of monovalent and divalent ions and radicals on the basis
of the compressible ion theory. In this theory, the compression energy of an ion is given as a two-parameter function of its
radius,A exp (−r/p), the radius and compressibility of the ion being monotonically decreasing functions of the compressing force acting on it.
Choosing a standard force reflecting the average environment in the alkali halides, univalent radii and compressibilities
have been calculated. This is the first theory to estimate ionic compressibilities. The values show systematic trends among
groups of related ions. Anions are found to be significantly more compressible than cations (e.g., the compressibilities of
Ca++, K+, Cl− and S− − are respectively 0.8530, 1.342, 2.952 and 5.150 × 10−12 cm2/ dyne). Multivalent or ‘crystal’ radii and compressibilities have also been calculated by scaling the standard force by the
square of the ionic charge. The calculated ionic radii are closer to experimental values than the classical empirical radii. 相似文献
463.
The kinetics of the oxidation of cyclopentanol, cyclohexanol, 2? methylcyclohexanol, and cycloheptanol by hexacyanoferrate(III) ions in mild alkaline medium has been studied in the presence of traces of ruthenium(VI) ≈ 10?7M at constant ionic strength (0.26M). The results suggest that the oxidation of the studied cyclic alcohols proceeds via the formation of a complex between Ru(VI) and the substrate which slowly decomposes, giving the reduced form of ruthenium which was reoxidized to Ru(VI) in a fast step by alkaline hexacyanoferrate(III) ions. The product study shows the production of the corresponding ketone. 相似文献
464.
Multiscale simulations are used to bridge the surfactant templated assembly of individual approximately 1-10 nm cobalt dots, to their ordering into supramolecular arrays. Potential energy surfaces derived from ab initio calculations are input to lattice Monte Carlo simulations at atomic scales. By this process we quantitatively reproduce the experimental cobalt nanoparticle sizes. Crucially, we find that there is an effective short range attraction between pairs of nanodots. Mesoscale simulations show that these attractive interdot potentials are so short ranged that the dots can assemble only into orientally ordered hexatic phases as in the experiments. 相似文献
465.
Adsorption of thiourea and some of its derivatives at the mercurysolution interface has been studied by the tensammetric technique. It has been found that adsorption of thiourea increased the differential capacity rather than decreasing it. However the adsorption of S-methyl derivative of thiourea decreased the differential capacity. The N-substituted derivatives depressed the tensammetric curve of the supporting electrolyte to a greater extent than the N, N1-substituted derivatives. The different behaviours of thiourea and its derivatives are discussed. 相似文献
466.
Pierce MS Buechler CR Sorensen LB Turner JJ Kevan SD Jagla EA Deutsch JM Mai T Narayan O Davies JE Liu K Dunn JH Chesnel KM Kortright JB Hellwig O Fullerton EE 《Physical review letters》2005,94(1):017202
Using coherent x-ray speckle metrology, we have measured the influence of disorder on major loop return point memory (RPM) and complementary point memory (CPM) for a series of perpendicular anisotropy Co/Pt multilayer films. In the low disorder limit, the domain structures show no memory with field cycling--no RPM and no CPM. With increasing disorder, we observe the onset and the saturation of both the RPM and the CPM. These results provide the first direct ensemble-sensitive experimental study of the effects of varying disorder on microscopic magnetic memory and are compared against the predictions of existing theories. 相似文献
467.
Sukriti Nigam B. S. Jayashree Aditya Narayan Pande N. D. Reddy J. Venkata Rao 《Research on Chemical Intermediates》2018,44(2):901-924
N-Benzyltetrahydropyridinyl-4,6-dimethoxy phenyl-substituted 2′-hydroxychalcones SJC1–15 were synthesized using Claisen–Schmidt condensation, their structures confirmed by spectral analysis, and their anticancer activity evaluated. To support their biological activity, physicochemical parameters such as lipophilicity and oxidation potential were determined. To assess their relative cytotoxicity, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was performed using MCF-7, T-47D, MDA MB-231, HepG2, and Vero cell lines. The cytotoxicity of the chalcones was found to vary with the nature of the ring B substituents. The lipophilicity of the cytotoxic compounds expressed in terms of distribution coefficient was found to lie in the range of 2.4–4.2. Further evaluation of their antioxidant potential revealed antioxidant activity by 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) radical scavenging assay and irreversible electrochemical reaction with oxidation potential in the range of 0.879–1.048 V. Of the 15 chalcones, SJC4, 5, 9 were selected for further in vitro studies using MCF-7. The compounds exhibited significant apoptotic effect and caused cell cycle arrest at G0/G1 and G2/M phase. Among them, two of the O-alkylated chalcones (SJC5, 9) showing promising activity against hormone-responsive breast cancer cells were evaluated for their in vivo anticancer activity using 7,12-dimethylbenz[a]anthracene (DMBA)-induced mammary tumor model. Three-week treatment with the test compounds at oral dosage of 100 mg kg?1 per day significantly improved elevated tumor parameters compared with tumor control. Treatment with chalcone SJC5 (a 2,4,5-trimethoxy derivative) exhibited anticancer effects similar to those of doxorubicin (2 mg kg?1 per week, i.p.) and was free from toxic effects observed with doxorubicin treatment. 相似文献
468.
Anirban Dutta Sumit K. Dutta Samrat Das Adhikari Dr. Narayan Pradhan 《Angewandte Chemie (International ed. in English)》2018,57(29):9083-9087
High temperature colloidal synthesis for obtaining thermal, colloidal and phase‐stable CsPbI3 nanocrystals with near‐unity quantum yield is reported. While standard perovskite synthesis reactions were carried out at 160 °C (below 200 °C), increase of another ≈100 °C enabled the alkylammonium ions to passivate the surface firmly and prevented the nanocrystals from phase transformation. This did not require any inert atmosphere storage, use of heteroatoms, specially designed ligands, or the ice cooling protocol. Either at high temperature in reaction flask or in the crude mixture or purified dispersed solution; these nanocrystals were observed stable and retained the original emission. Different spectroscopic analyses were carried out and details of the surface binding of alkyl ammonium ligands in place of surface Cs in the crystal lattice were investigated. As CsPbI3 is one of the most demanding optical materials, bringing stability by proper surface functionalization without use of secondary additives would indeed help in wide spreading of their applications. 相似文献
469.
470.
Enantiopure 2-(tributylstannyl)pyrrolidine hydroiodide may be prepared in excellent yield by TMSI treatment of the corresponding N-Boc compound, which is in turn prepared by asymmetric deprotonation (s-BuLi.sparteine) and stannylation, as described in the literature. Crystals of the hydroiodide salt suitable for X-ray analysis were obtained, and although there is some disorder about the butyl groups, analysis using anomalous dispersion establishes the absolute configuration as S. 相似文献