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1.
Nano palladium supported on high‐surface‐area metal–organic framework MIL‐101: an efficient catalyst for Sonogashira coupling of aryl and heteroaryl bromides with alkynes 下载免费PDF全文
Manne Annapurna T. Parsharamulu P. Vishnuvardhan Reddy M. Suresh Pravin R. Likhar Mannepalli Lakshmi Kantam 《应用有机金属化学》2015,29(4):234-239
Palladium nanoparticle‐incorporated metal–organic framework MIL‐101 (Pd/MIL‐101) was successfully synthesized and characterized using X‐ray diffraction, nitrogen physisorption, X‐ray photoelectron, UV–visible and infrared spectroscopies, and transmission electron microscopy. The characterization techniques confirmed high porosity and high surface area of MIL‐101 and high stability of nano‐size palladium particles. Pd/MIL‐101 nanocomposite was investigated for the Sonogashira cross‐coupling reaction of aryl and heteroaryl bromides with various alkynes under copper‐free conditions. The reusability of the catalyst was tested for up to four cycles without any significant loss in catalytic activity. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
2.
This paper examines the economic logic of integrated assessment — balancing the costs against the benefits of greenhouse gas abatement. Stylized facts are employed in a multiregion computable general equilibrium model with a public good. The percentage shares of global emissions are determined outside the model — based upon some form of international agreement — and emission rights are tradeable between regions. The analysis is confined to Pareto-optimal (cooperative) solutions. We focus on the sensitivity of initial decisions to low-probability, high-consequence scenarios associated with cumulative emissions. For simplicity, there are only two regions, two tradeable goods, two time periods, and two states-of-world. With the particular form of public good model adopted here (production rather than utility function impacts), it turns out that a Pareto-optimal hedging strategy is indepedent of the emission shares allocated to each region. Equity issues may be separated from those of economic efficiency. Similar results extend to cases in which there are additional regions, tradeable goods, time periods, and states-of-world.Presented at the Conference on the Economics of Global Environmental Change, Birmingham University, May 9–11, 1994. This research was funded by the Electric Power Research Institute (EPRI). The views presented here are solely those of the individual authors, and do not necessarily represent the views of EPRI or its members. 相似文献
3.
This paper deals with the preparation and optical analysis of Er3+ (0.2 mol%) boro-fluoro-phosphate glasses in the following glass compositions:
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Series A: 69.8 B2O3–10 P2O5–10(ZnO/CdO/TeO2)–10 AlF3
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Series B: 69.8 B2O3–10 P2O5–10(ZnO/CdO/TeO2)–10 LiF
4.
Spherically symmetric static cosmological models filled with black-body radiation are considered. The models are isotropic
about a central observer but inhomogeneous. It is suggested that the energy density of the free gravitational field, which
is coupled to the isotropic radiation energy density, might play an important role in generating sufficient field (vacuum)
energy (when converted into thermal energy) and initiate processes like inflation. On the central world line the energy density
of the free gravitational field vanishes whereas the proper pressure and density of the isotropic black-body radiation are
constants. Further, it is shown that the cosmological constant is no more arbitrary but given in terms of the central pressure
and density. Also, at its maximum value the energy density of the free gravitational field is proved to be equal to one third
of the combined value of radiation pressure and density. 相似文献
5.
Reenamoni Saikia Chaliha K. Annapurna Anal Tarafder V.S. Tiwari P.K. Gupta Basudeb Karmakar 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2010,75(1):243-250
Precursor glass of composition 25K2O–25Nb2O5–50SiO2 (mol%) doped with Er2O3 (0.5 wt% in excess) was isothermally crystallized at 800 °C for 0–100 h to obtain transparent KNbO3 nanostructured glass–ceramics. XRD, FESEM, TEM, FTIRRS, dielectric constant, refractive index, absorption and fluorescence measurements were carried out to analyze the morphology, dielectric, structure and optical properties of the glass–ceramics. The crystallite size of KNbO3 estimated from XRD and TEM is found to vary in the range 7–23 nm. A steep rise in the dielectric constant of glass–ceramics with heat-treatment time reveals the formation of ferroelectric nanocrystalline KNbO3 phase. The measured visible photoluminescence spectra have exhibited green emission transitions of 2H11/2, 4S3/2 → 4I15/2 upon excitation at 377 nm (4I15/2 → 4G11/2) absorption band of Er3+ ions. The near infrared (NIR) emission transition 4I13/2 → 4I15/2 is detected around 1550 nm on excitation at 980 nm (4I15/2 → 4I11/2) of absorption bands of Er3+ ions. It is observed that photoluminescent intensity at 526 nm (2H11/2 → 4I15/2), 550 nm (4S3/2 → 4I15/2) and 1550 nm (4I13/2 → 4I15/2) initially decrease and then gradually increase with increase in heat-treatment time. The measured lifetime (τf) of the 4I13/2 → 4I15/2 transition also possesses a similar trend. The measured absorption and fluorescence spectra reveal that the Er3+ ions gradually enter into the KNbO3 nanocrystals. 相似文献
6.
The general dynamical equations for perfect fluid filled spheres with an outward flux of photons are derived. The vital role
played by the energy density of the free gravitational field in accelerating photon production has been emphasized. It is
pointed out that even when the material energy density is finite, the energy density of the free gravitational field can take
infinitely large values resulting in vanishing surface area of the star. A generalized Schwarzschild interior solution with
conformally flat geometry but with photon emission has been obtained. It is pointed out that the interior conformal coordinate
system bears a strong resemblance to the exterior Krushkal coordinates. It is shown that for spherical star the invariant
velocity of the fluid particles, falling towards the centre, is proportional to its radius suggesting that the outer envelopes
collapse at a faster rate than the core part. It is shown that the interior radiating solution can be matched with generalized
Schwarzchild exterior solution. 相似文献
7.
Manne Naga RajuNeelam Uday Kumar Baddam Sudhakar ReddyNaredla Anitha Gangula SrinivasApurba Bhattacharya Kagga MukkantiNaveenkumar Kolla Rakeshwar Bandichhor 《Tetrahedron letters》2011,52(42):5464-5466
An alternative and scalable synthesis of dexlansoprazole ((R)-(+)-1); the (R)-enantiomer of Lansoprazole with an enantiomeric excess of >99.8% is presented. 相似文献
8.
A new and general semiempirical method for calculating ionization energies of molecules containing heavy atoms is presented. The extended Hückel hamiltonian is amended with a phenomenological one-electron spin-orbit interaction operator, and ionization energies are equated to orbital energies according to Koopmans' theorem. Calculations are presented for molecules with Br and I as heavy atoms. The systems considered are the hydrogen halides, diatomic halogens and interhalogens, haloacetylenes, halomethanes, and boron trihalides. Good agreement with the observed spin-orbit splitting is obtained. New assignments are proposed for the trihalides considered. 相似文献
9.
Nowduri Annapurna Adari Kalyan Kumar Parvataneni Vani Gollapalli Nageswara Rao 《Transition Metal Chemistry》2008,33(6):691-696
The kinetics of oxidation of l-cystine by MnIII have been studied in sulfuric acid medium at 30 °C. The reaction was followed spectrophotometrically at λmax = 500 nm. The
reaction shows first order dependence on both [MnIII] and [cystine]. It was found that the rate of the reaction decreases with increase of [H+] up to a certain point and then remains unchanged. The oxidation product of the reaction was found to be cysteic acid. A
plausible mechanism has been proposed to account for the experimental results. 相似文献
10.
Rolf Manne 《Chemical physics letters》1977,45(3):470-472
A theorem concerning the completeness of operator manifolds used for the generation of ionized electronic states by direct methods is formulated and proven. 相似文献