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681.
Katja Burek Dr. Joachim Dengler Dr. Franziska Emmerling Ines Feldmann Prof. Michael U. Kumke Dr. Julia Stroh 《ChemistryOpen》2019,8(12):1441-1452
The hydration process of Portland cement in a cementitious system is crucial for development of the high-quality cement-based construction material. Complementary experiments of X-ray diffraction analysis (XRD), scanning electron microscopy (SEM) and time-resolved laser fluorescence spectroscopy (TRLFS) using europium (Eu(III)) as an optical probe are used to analyse the hydration process of two cement systems in the absence and presence of different organic admixtures. We show that different analysed admixtures and the used sulphate carriers in each cement system have a significant influence on the hydration process, namely on the time-dependence in the formation of different hydrate phases of cement. Moreover, the effect of a particular admixture is related to the type of sulphate carrier used. The quantitative information on the amounts of the crystalline cement paste components is accessible via XRD analysis. Distinctly different morphologies of ettringite and calcium−silicate−hydrates (C−S−H) determined by SEM allow visual conclusions about formation of these phases at particular ageing times. The TRLFS data provides information about the admixture influence on the course of the silicate reaction. The dip in the dependence of the luminescence decay times on the hydration time indicates the change in the structure of C−S−H in the early hydration period. Complementary information from XRD, SEM and TRLFS provides detailed information on distinct periods of the cement hydration process. 相似文献
682.
It is usually believed that a picture of Quantum Mechanics in terms of true probabilities cannot be given due to the uncertainty relations. Here we discuss a tomographic approach to quantum states that leads to a probability representation of quantum states. This can be regarded as a classical‐like formulation of quantum mechanics which avoids the counterintuitive concepts of wave function and density operator. The relevant concepts of quantum mechanics are then reconsidered and the epistemological implications of such approach discussed. 相似文献
683.
Ulrich Schubert Kurt Mereiter Ines Elhofer 《Monatshefte für Chemie / Chemical Monthly》2000,14(1):931-936
The crystal structure of consists of individual layers in which the anionic complexes form strings of vertex-sharing octahedral units. These strings are interconnected by units to form layers via Na-Cl and Na-O interactions. An outstanding feature of the compound are the unusually strong Jahn-Teller elongated trans- octahedra. 相似文献
684.
685.
Ryhänen SJ Säily VM Parry MJ Luciani P Mancini G Alakoskela JM Kinnunen PK 《Journal of the American Chemical Society》2006,128(26):8659-8663
While much is known about the self-assembly of lipids on nanoscale, our understanding of their biologically relevant mesoscale organization remains incomplete. Here, we show for a cationic gemini lipid a sharp and reversible transition from small vesicles with an average diameter of approximately 40 nm to giant vesicles (GVs) with an average diameter of approximately 11 microm. This transition is dependent on proper [NaCl] and specific temperature. Below this transition and in the vicinity of the air/water interface, a series of mesoscale morphological transitions was observed, revealing complex structures resembling biological membranes. On the basis of microscopy experiments, a tentative [NaCl] versus temperature shape/size phase diagram was constructed. To explain this unprecedented transition, we propose a novel mechanism whereby a specific interaction of Cl(-) counterion with the cationic gemini surfactant initiates the formation of a commensurate solute counterion lattice with low spontaneous curvature. In keeping with the high bending rigidity of NaCl crystal, this tightly associated ionic lattice enslaves membrane curvature and the mesoscale 3-D organization of this lipid. 相似文献
686.
H. Moradpour Y. Heydarzade F. Darabi Ines G. Salako 《The European Physical Journal C - Particles and Fields》2017,77(4):259
A generalized version for the Rastall theory is proposed showing the agreement with the cosmic accelerating expansion. In this regard, a coupling between geometry and the pressureless matter fields is derived which may play the role of dark energy, responsible for the current accelerating expansion phase. Moreover, our study also shows that the radiation field may not be coupled to the geometry in a non-minimal way which represents that the ordinary energy-momentum conservation law is respected by the radiation source. It is also shown that the primary inflationary era may be justified by the ability of the geometry to couple to the energy-momentum source in an empty flat FRW universe. In fact, this ability is independent of the existence of the energy-momentum source and may compel the empty flat FRW universe to expand exponentially. Finally, we consider a flat FRW universe field by a spatially homogeneous scalar field evolving in potential \(\mathcal {V}(\phi )\), and study the results of applying the slow-roll approximation to the system which may lead to an inflationary phase for the universe expansion. 相似文献
687.
R.C. Mancini C.A. Iglesias S. Ferri A. Calisti R. Florido 《High Energy Density Physics》2013,9(4):731-736
The effect of the interference term in the electron broadening of the Li-like satellites to the Ar Heβ line has been investigated in the standard Stark broadening theory. Although the interference term has negligible or small effect on satellite lines with spectator electrons in n = 2 and n = 3 shells, it shows significant narrowing for lines with n = 4 spectator electrons. Nevertheless, the improved n = 4 satellite line shape makes a small difference in the emergent intensity distribution of the composite spectral feature. Accordingly, this change in line shape does not affect previous diagnosis of plasma conditions in Ar-doped ICF implosion cores. 相似文献
688.
689.
Franco Benetollo Marilena Mancini Carlo Santini 《Journal of organometallic chemistry》2005,690(8):1994-2001
The new sodium bis(2-pyridylthio)acetate ligand, Na[(pyS)2CHCO2], has been prepared in ethanol solution using 2-mercaptopyridine, dibromoacetic acid and NaOH. New mono- and di-organotin(IV) derivatives containing the anionic bis(2-pyridylthio)acetate have been synthesized from reaction between SnRnCl4−n (R = Me, Ph and nBu, n = 1-2) acceptors and Na[(pyS)2CHCO2]. Mono-nuclear complexes of the type {[(pyS)2CHCO2]RnSnCl4−n−1} have been obtained and characterized by elemental analyses, FT-IR, ESI-MS, multinuclear (1H and 119Sn) NMR spectral data and X-ray crystallography. ESI-MS spectra of methanol solution of the complexes show the existence of hydrolysed species. Attempts to crystallize the dimethyltin(IV) derivative (3), from acetonitrile solution yield the dimeric dicarboxylatotetramethyldistannoxane (8), which was characterized by single crystal diffraction analysis. 相似文献
690.