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351.
A highly efficient and simple protocol for the preparation of 2-arylbenzothiazoles through condensation of 2-aminothiophenol and different aldehydes in the presence of H3PO4/TiO2-ZrO2(1/1)-cetyl pyridinium bromide (CPB) is described. The reaction proceeded under mild and solvent-free conditions to afford 2-arylbenzothiazole derivatives. In this method, the title compounds were obtained in good to excellent yields and short reaction times. The structures of synthesized products were identified by infrared, 1H NMR, 13C NMR, and mass spectroscopy. 相似文献
352.
In this paper, we formulate a nonlinear elasticity theory in which the ambient space is evolving. For a continuum moving in an evolving ambient space, we model time dependency of the metric by a time-dependent embedding of the ambient space in a larger manifold with a fixed background metric. We derive both the tangential and the normal governing equations. We then reduce the standard energy balance written in the larger ambient space to that in the evolving ambient space. We consider quasi-static deformations of the ambient space and show that a quasi-static deformation of the ambient space results in stresses, in general. We linearize the nonlinear theory about a reference motion and show that variation of the spatial metric corresponds to an effective field of body forces. 相似文献
353.
A novel microfluidic concept for bioanalysis using freely moving beads trapped in recirculating flows 总被引:1,自引:0,他引:1
There are only a few examples in which beads are employed for heterogeneous assays on microfluidic devices, because of the difficulties associated with packing and handling these in etched microstructures. This contribution describes a microfluidic device that allows the capture, preconcentration, and controlled manipulation of small beads (<6 microm) in etched microchannels using fluid flows only. The chips feature planar diverging and converging channel elements connected by a narrow microchannel. Creation of bi-directional liquid movement by opposing electro-osmotic and pressure-driven flows can lead to the generation of controlled recirculating flow at these elements. Small polymer beads can actually be captured in the controlled rotating flow patterns. The clusters of freely moving beads that result can be perfused sequentially with different solutions. A preliminary binding curve was determined for the reaction of streptavidin-coated beads and fluorescein-labelled biotin, demonstrating the potential of this bead-handling approach for bioanalysis. 相似文献
354.
Mohammad Reza Ganjali Vahideh Akbar Azadeh Daftari Parviz Norouzi Hooshang Pirelahi Arash Mouradzadegun 《中国化学会会志》2004,51(2):309-314
A highly selective PVC‐membrane electrode based on 2,6‐diphenylpyrylium fluoroborate is presented. The electrode reveals a Nernstian potentiometric response for sulfate ion over a wide concentration range (5.0 × 10?6‐1.0 × 10?1 M). The electrode has a response time of about 10 s and can be used for at least 2 months without any divergence. The proposed sensor revealed very good selectivities for sulfate over a wide variety of common organic and inorganic anions and could be used over a wide pH range (2.5–9.5). The detection limit of the sensor is 3.0 × 10?6 M. It was successfully applied to the direct determination of salbutamol, paramomycin tablets, and as an indicator electrode for potentiometric titration of sulfate ions with barium ions. 相似文献
355.
A new procedure has been developed for chromium speciation in aqueous solution by the use of micellar, ion-association, solid-phase extraction techniques (SPE) followed by flame atomic absorption spectrometry. The method was based on the use of C-18 bonded phase silica SPE disks for retention of ion-associated Cr(VI) with cetyl trimethyl ammonium bromide (CTAB), elution of the retained species and subsequent detection by flame atomic absorption spectrometry (FAAS). Cr(III) was oxidized by potassium persulfate to Cr(VI), then the total chromium was retained on the disk and determined by FAAS. The amount of Cr(III) was calculated by the difference between the total and Cr(VI) values. The calculated limit of detections (LOD) (based on 3sigma) are 15 microg L(-1) and 20 microg L(-1) for Cr(VI) and Cr(III) respectively. No considerable interferences have been observed from other investigated anions and cations and the method has been successfully applied to water samples taken from the Karoon River in Khuzestan province. 相似文献
356.
We summarize the program pursued by Michael J. Moravcsik and the authors on spin amplitude analyses and interpretation. We present the recent observations that phase histograms reveal striking peaks corresponding to spin amplitudes that tend to have definite simple phase relations. An interpretation is proposed in which the spin amplitudes receive a coherent and an incoherent contribution over large ranges of energies and angles. Continuing research directions are reported.Dedicated to the memory of Michael J. Moravcsik, whose contribution to this work, our research, and spin physics is immeasurable 相似文献
357.
The X‐ray crystal structures of [PtCl2(dppm)], [Pt(C6F5)2L] (L = dppm (bis(diphenylphosphino)methane), dpam (bis(diphenylarsino)methane), dpae (bis(diphenylarsino)ethane)) and [PtCl(C6F5)(dpae)] show the complexes to be monomeric with chelating dipnictido ligands, and not alternatives with bridging ligands. In [Pt(C6F5)2(dpam)2], there are two unidentate diarsine ligands in a cis‐arrangement. 相似文献
358.
Mohammad Reza Ganjali Parviz Norouzi Mehdi Emami Mahmoud Golmohammadi Arash Mouradzadegun 《中国化学会会志》2006,53(5):1209-1214
A PVC‐based membrane sensor was prepared for Cs+ ions, which was based on 7,11,15,28‐tetraiodo‐1,21,23,25‐tetramethyl‐2,20:3,19‐dimethano‐1H,21H,23H,25H‐bis[1,3]dioxocino[5,4‐i:5′,4′i′] benzo[1,2‐d:5,4‐d′]‐bis[1,3]benzodioxocin stereoisomer (cavitand). The proposed membrane electrode exhibits a linear dynamic range of 1.0 × 10?;1–1.0 × 10?;5M, with a Nernstian slope of 59.1 ± 0.3 mV per decade, and a detection limit of 5.0 × 10?;6 M. It has a very fast response time of <10 s and can be used for at least eight weeks without any considerable divergence in its potentials. The best sensor performance was obtained with a membrane containing 30% PVC, 62% dibutylphthalate (DBP), 6% cavitand, and 2% potassium tetrakis(p‐chlorophenyl) borate (KTpClPB). The sensor could be used in a pH range of 4.3–9.5. 相似文献
359.
Arash Yavari Arkadas Ozakin 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》2008,59(6):1081-1110
In this paper we covariantly obtain all the governing equations of linearized elasticity. Our motivation is to see if one
can make a connection between invariance (covariance) properties of the (global) balance of energy in nonlinear elasticity
and those of its counterpart in linear elasticity. We start by proving a Green-Naghdi-Rivilin theorem for linearized elasticity.
We do this by first linearizing energy balance about a given reference motion and then by postulating its invariance under
isometries of the Euclidean ambient space. We also investigate the possibility of covariantly deriving a linearized elasticity
theory, without any reference to the local governing equations, e.g. local balance of linear momentum. In particular, we study
the consequences of linearizing covariant energy balance and covariance of linearized energy balance. We show that in both
cases, covariance gives all the field equations of linearized elasticity.
相似文献
360.
Eva Kanso Marino Arroyo Yiying Tong Arash Yavari Jerrold G. Marsden Mathieu Desbrun 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》2007,58(5):843-856
This paper shows that the stress field in the classical theory of continuum mechanics may be taken to be a covector-valued
differential two-form. The balance laws and other fundamental laws of continuum mechanics may be neatly rewritten in terms
of this geometric stress. A geometrically attractive and covariant derivation of the balance laws from the principle of energy
balance in terms of this stress is presented.
Jerrold G. Marsden: Research partially supported by the California Institute of Technology and NSF-ITR Grant ACI-0204932. 相似文献