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101.
New Pd(II) and Pt(II) 3,6-bis(2′-pyridyl)pyridazine (dppn) mononuclear complexes of the type M(dppn)Cl2 were prepared and characterized. From M(dppn)Cl2, the bimetallic homonuclear complexes M(dppn)MCl4 were prepared by reaction with Pd(PhCN)2Cl2 or K2PtCl4. Bimetallic heteronuclear species of the type M(dppn)M′Cl4, were prepared reacting the mononuclear complexes with the stoichiometric amount of M′Cl2 (M′ = Cu, Co, Ni). All the described reaction give product in high yield. The isolated compounds, almost completely insoluble in most organic solvents, were characterized by elemental analysis, IR, ESR, reflectance spectra, and magnetic moment measurements. On the basis of these data the geometries around the metals are discussed. 相似文献
102.
Maria Antonia Iat Rosalba Saija Arianna Giusto Paolo Denti Ferdinando Borghese Cesare Cecchi-Pestellini 《Journal of Quantitative Spectroscopy & Radiative Transfer》2006,100(1-3):157-164
We calculate the energy density distribution in the ultraviolet within small spheres containing concentric cavities, aimed at simulating interstellar dust grains. We explore the dependence on chemical composition by progressively changing, in an arbitrary way, the refractive index of the sphere material. We conclude that a significant fraction of the energy of the impinging radiation is trapped throughout the particle interior. 相似文献
103.
L.S. Campana A. Caramico DAuria M. DAmbrosio L. De Cesare U. Esposito 《Physica A》1984,123(1):279-295
The paper is devoted to an investigation of the damping effects of the Fermion elementary excitations in the Jordan-Wigner representation of a one-dimensional anisotropic model in an external field. This is realized on the basis of the “Gaussian ansatz”, recently proposed by Nolting and Oles, as substituting the standard “polar ansatz” in the Spectral Density Method, for exploring damping effects of quasi-particles in many-body problems. By using a first order approximation, we are able to obtain reasonable results in the low temperature limit. 相似文献
104.
Mariateresa Giustiniano Sveva Pelliccia Ettore Novellino Gian Cesare Tron 《Tetrahedron letters》2018,59(13):1196-1199
N-Substituted α-amino acid amides can be easily obtained in two steps using the four-component Ugi reaction followed by chemoselective cleavage of the resulting tertiary amide. The use of the sacrificial acid, 2-hydroxymethylbenzoic acid is associated to shorter reaction times, higher yields, and safer and greener reaction conditions compared to strategies based on trifluoroacetic acid, a toxic and environmental hazardous reagent. The optimized procedure was easily scaled up to gram amounts. 相似文献
105.
R. Bucci V. Carunchio A. D. Magri A. L. Magri 《Journal of Thermal Analysis and Calorimetry》1984,29(4):679-686
The thermal properties of some complexes of copper(II) with pyridine-2-aldoxime (HPAO), where the ligand appears either as the ion (PAO–) or as a neutral molecule, were determined in vacuo and in dynamic nitrogen and oxygen gas atmospheres. The study was carried out by thermoanalytical (TG, DTG. DTA), spectroscopic and spectrometric (UV-visible, IR, diffuse reflectance, mass) techniques.The initial decomposition temperature is influenced by the number of acid hydrogens in the complex; the thermal stability sequence in vacuo is: [Cu(PAO)2H]Cl > [Cu(PAO)2H2]Cl2 > [Cu(PAO)2]The thermal decomposition reactions occur in several separate steps, the first of which gives rise to partial ligand decomposition, the reduction of copper(II) to copper(I), and the conversion of the residual pyridine-2-aldoxime into acid amide.
Zusammenfassung Die thermischen Eigenschaften einiger Komplexe von Kupfer(II) mit Pyridin-2-aldoxim (HPAO), in denen der Ligand entweder als Ion (PAO–) oder als neutrales Molekül vorliegt, wurden im Vakuum und in dynamischer N2- und O2-Atmosphäre ermittelt. Zur Untersuchung wurden thermoanalytische (TG, DTG, DTA) und spektrometrische (UV-sichtbar, IR, diffuse Reflektionsspektrophotometrie, Massenspektrometrie) Techniken herangezogen. Die Temperatur, bei der die Zersetzung beginnt, wird durch die Zahl der sauren Wasserstoffatome im Komplex beeinflußt; für die thermische Stabilität im Vakuum gilt die Reihenfolge [Cu(PAO)2H]Cl > [Cu(PAO)2H2]Cl2 > [Cu(PAO)2]. Die thermischen Zersetzurigsreaktionen verlaufen in mehreren diskreten Schritten, wobei der erste von diesen eine partielle Zersetzung des Liganden, die Reduktion von Kupfer(II) zu Kupfer(I) und die Konversion des verbleibenden Pyridin-2-aldoxims in das Säureamid in sich einschließt.
-2- ( ), (-), . (, , ) , - , , - . , [Cu(PAO)2H]CI > [Cu(PAO)2H2]Cl2 > [Cu(PAO)2] , , -2- .相似文献
106.
Cesare Oliva Marco Scavini Agusti Sin Yuri Dubitsky 《Journal of solid state chemistry》2004,177(11):4104-4111
EPR analysis is carried out with Ce1−xGdxO(4−x)/2 (x=0.1; 0.2) nanopowders aiming at obtaining information about their oxidation and reduction properties. The EPR spectrum of these systems is composed of a single feature. The first derivative peak-to-peak spectral intensity decreases at higher temperatures, but this trend deviates from that of Curie's law with the x=0.1 sample, at difference with the x=0.2 sample. This unexpected result is related to oxygen deficiency, due to gas-solid equilibrium, present in the former sample only. As a consequence, some Ce3+ ions would form providing it with conduction electrons propagating as small polarons in a percolative way. This would result in a thinner skin depth at higher temperatures, able to explain the deviation of the spectral intensity from its expected value. Indeed, this deviation from Curie's law is reduced or disappears at all after thermal treatment of the x=0.1 sample with O2. 相似文献
107.
The occurrence of non-abelian anomalies in gauge theories and gravitation, first discovered via perturbative techniques, is now completely explained from the mathematical point of view by means of the family index theorem of Atiyah and Singer. Here we make contact between this approach and BRS cohomology, by showing that they yield the same non-abelian anomalies, provided a certain restriction to local functionals is not introduced from the very beginning. In particular, this solves the unicity problem for this kind of anomalies. Local BRS cohomology is still relevant for the abelian case.Work partially supported by Gruppo Nazionale di Fisica Matematica del CNR and Progetto Nazionale Geometria e Fisica del MPI 相似文献
108.
Alberto Dal Corso Valentina Borlandelli Cristina Corno Paola Perego Laura Belvisi Luca Pignataro Cesare Gennari 《Angewandte Chemie (International ed. in English)》2020,59(10):4176-4181
Self‐immolative (SI) spacers are sophisticated chemical constructs designed for molecular delivery or material degradation. We describe herein a (S)‐2‐(aminomethyl)pyrrolidine SI spacer that is able to release different types of anticancer drugs (possessing either a phenolic or secondary and tertiary hydroxyl groups) through a fast cyclization mechanism involving carbamate cleavage. The high efficiency of drug release obtained with this spacer was found to be beneficial for the in vitro cytotoxic activity of protease‐sensitive prodrugs, compared with a commonly used spacer of the same class. These findings expand the repertoire of degradation machineries and are instrumental for the future development of highly efficient delivery platforms. 相似文献
109.
Philippe Remuzon Daniel Bouzard Pierre Di Cesare Christian Dussy Jean-Pierre Jacquet Alexandre Jaegly 《Journal of heterocyclic chemistry》1992,29(4):985-989
The 5-hydroxymethyl and the 5-formyl-1-cyclopropyl-6-fluoro-7-piperazinyl-1,4-dihydro-4-oxo-1,8-naphthyridine-3-carboxylic acids have been prepared via a 5-trimethylsilyl group and were tested in vitro as potential antibacterials. 相似文献
110.