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141.
A novel, microwave-assisted, palladium-catalyzed Sonogashira-type coupling of terminal alkynes with a variety of heteroaryl thiomethylethers is reported. The developed protocol allows for further utility and diversification of a number of chemically and biologically interesting scaffolds.  相似文献   
142.
The relationships between diffusivity and the excess, pair and residual multiparticle contributions to the entropy are examined for Lennard-Jones liquids and binary glassformers, in the context of approximate inverse power law mappings of simple liquids. In the dense liquid where diffusivities are controlled by collisions and cage relaxations, Rosenfeld-type excess entropy scaling of diffusivities is found to hold for both crystallizing as well as vitrifying liquids. The crucial differences between the two categories of liquids emerge only when local cooperative effects in the dynamics result in significant caging effects in the time-dependent behaviour of the single-particle mean square displacement. In the case of glassformers, onset of such local cooperativity coincides with onset of deviations from Rosenfeld-type excess entropy scaling of diffusivities and increasing spatiotemporal heterogeneity. In contrast, for two- and three-dimensional liquids with a propensity to crystallise, the onset of local cooperative dynamics is sufficient to trigger crystallization provided that the liquid is sufficiently supercooled that the free energy barrier to nucleation of the solid phase is negligible. The state points corresponding to onset of transient caging effects can be associated with typical values, within reasonable bounds, of the excess, pair, and residual multiparticle entropy as a consequence of the isomorph-invariant character of the excess entropy, diffusivity and related static and dynamic correlation functions.  相似文献   
143.
The feasibility of using tetragonal nano-zirconia (t-ZrO2) as an effective sorbent for developing a 99Mo/99mTc chromatographic generator was demonstrated. The structural characteristics of the sorbent matrix were investigated by different analytical techniques such as XRD, BET surface area analysis, FT-IR, TEM etc. The material synthesized was nanocrystalline, in tetragonal phase with an average particle size of ~7 nm and a large surface area of 340 m2 g?1. The equilibrium sorption capacity of t-ZrO2 is >250 mg Mo g?1. The present study indicates that 99Mo is both strongly and selectively retained by t-ZrO2 at acidic pH and 99mTc could be readily eluted from it, using 0.9% NaCl solution. A 9.25 GBq (250 mCi) t-ZrO2 based chromatographic 99Mo/99mTc generator was developed and its performance was repeatedly evaluated for 10 days. 99mTc could be eluted with >85% yield having acceptable radionuclidic, radiochemical and chemical purity for clinical applications. The compatibility of the product in the preparation of 99mTc labeled formulations such as 99mTc-EC and 99mTc-DMSA was evaluated and found to be satisfactory.  相似文献   
144.
Terpyridine copper(II) complexes [Cu(L)2](NO3)2, where L is (4′-phenyl)-2,2′:6′,2′′-terpyridine (ph-tpy in 1) and [4′-(1-pyrenyl)]-2,2′:6′,2′′-terpyridine (py-tpy in 2), are prepared, characterized and their photocytotoxic activity studied. The crystal structure of complex 1 shows distorted octahedral CuN6 coordination geometry. The 1:2 electrolytic and one-electron paramagnetic complexes show a visible band near 650 nm in DMF–H2O. The complexes show emission band at 352 nm for 1 and 425 nm for 2 when excited at 283 and 346 nm, respectively. The Cu(II)–Cu(I) redox couple is observed near −0.2 V versus SCE in DMF–0.1 M TBAP. The complexes are avid partial-intercalative binders to calf thymus DNA giving binding constant (Kb) values of ∼106 M−1. Complex 2 with its photoactive pyrenyl moiety exhibits significant photocleavage of pUC19 DNA in red light via singlet oxygen pathway. Complex 2 also exhibits significant photo-activated cytotoxicity in HeLa cancer cells in visible light giving IC50 value of 11.9 μM, while being non-toxic in dark with an IC50 value of 130.5 μM.  相似文献   
145.
Some computational aspects of the characterization of the complex hydrogen bond network dynamics using power spectral analysis are discussed. In the case of hydrogen-bonded liquids, the tagged molecule potential energy is shown to be a useful quantity for capturing the behavior of the networked liquid on different lengths and time scales. The computation of the tagged potential energy for rigid-body effective pair potentials, such as the TIP5P-E and SPC-E models, is discussed. The more structured nature of the TIP5P-E potential, compared to the SPC/E potential, shows up as differences in the high-frequency librational band of the power spectra of the tagged molecule potential energies. The static distributions of the tagged molecule potential energies are also more structured in the case of TIP5P-E, rather than SPC/E, water. The overall behavior of the key power spectral features remains the same in both the models. The possibility of detailed characterization of the power spectrum, and therefore of the underlying dynamics, using a model-based parametric fitting procedure for the power spectra is also discussed. We show that a parametric fitting can allow one to test alternative models of the dynamics underlying the liquid state dynamics.  相似文献   
146.
Foreword     
P Sugathan  N Madhavan  AK Sinha  R Singh 《Pramana》1999,53(3):363-364
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147.
Determining the blood glucose level is important for the prevention and treatment of diabetes mellitus. We developed a sensor system using Quartz Crystal Microbalance (QCM) to determine the blood glucose level from human blood serum. This study consists of two experimental stages: artificial glucose/pure water solution tests and human blood serum tests. In the first stage of the study, the QCM sensor with the highest performance was identified using artificial glucose solution concentrations. In the second stage of the study, human blood serum measurements were performed using QCM to determine blood glucose levels. QCM sensors were coated with phthalocyanines (Pcs) by jet spray method. The blood glucose values of 96 volunteers, which ranged from 71 mg/dL to 329 mg/dL, were recorded. As a result of the study, human glucose values were determined with an average error of 3.25%.  相似文献   
148.
In this paper, a conceptual schematic for the search radar has been presented which offers clutter cancellation as well as blind speed elimination. It is assumed that the radar is performing conical scan in both azimuth and elevation. For such cases, strong clutter signals are likely to be intercepted from off-boresight angles. A pulse-to-pulse comparison method is presented where the radar transmits and receives SUM beam during the first pulse and DIFFERENCE beam in the second pulse. The detected voltages for the echoes received during the pulse intervals are subtracted from each other and the negative voltage at the output of subtractor is discarded. This result in a narrow beam pointed in the direction of angle of arrival. This method, in receive only mode, can also be used for calibration of large phased arrays.  相似文献   
149.
A simple and general approach to the synthesis of chemical libraries based on a universal anhydride template allows the preparation of large number of compounds. Various cyclic/acyclic amines, primary/secondary amines, differentially protected bifunctional amines were used as nucleophiles to react with anhydrides. The free carboxylic acid generated was then coupled with solid-bound amines. The facile and rapid generation of compounds through this multi-component assembly can be accomplished in a combinatorial parallel synthesis. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   
150.
To generalize inherent structure analysis to understand structural changes in quantum liquids and solids, differences between classical (V(x)) and quantum-corrected (U(qeff)(x)) energy landscapes are estimated as a function of the de Boer parameter (Λ). Path integral simulations of quantum Lennard-Jones solids are performed at zero pressure and a dimensionless reduced temperature of 0.123, corresponding to an absolute temperature of 4.2K. At constant temperature and pressure, Λ is increased from the classical limit of zero to Λ = 0.28, corresponding to para-H(2). Increasing quantum delocalization effects result in a continuous decrease in density and local order but without a transition to a disordered, liquid state. The inherent structure landscape of bulk systems is strongly dependent on density with the energy and stability of crystalline minima decreasing relative to that of amorphous packing minima as the system is stretched. For Λ ≈ 0.23, the volume fluctuations in quantum solids are sufficient to result in sampling of disordered minima while for Λ = 0.28, the underlying classical inherent structures are completely disordered, indicating that the topography of U(qeff)(x) and V(x) are qualitatively different for such values of Λ. To assess the nature of the quantum-corrected energy landscape, effective pair potentials are defined by u(qeff)(r) = -kT ln g(r) using the pair correlation function (g(r)) of the quantum system in the neighborhood of the first peak. Our results show that as Λ increases, the pair potentials become increasingly softer, shallower, and of increasing range with a shifting of the potential minimum to larger distances. For example, the reduction of the entropy of fusion and melting temperatures of quantum solids with increasing Λ are analogous to the changes in thermodynamics of melting seen in classical solids with increasing range and softness of interactions. The energy landscapes associated with such coarse-grained potentials should be useful as predictors of structural transformations in quantum systems, analogous to their use in understanding phase diagrams of complex fluids.  相似文献   
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