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981.
Zusammenfassung Durch potentiometrische Untersuchung des Verhaltens von Resorufin, o-Acetylresorufin und Äthoxyresorufin wurde festgelegt, unter welchen Bedingungen es zur Bildung von Semichinon kommt. Ferner wurden die Bedingungen für die titanometrische und stannometrische Bestimmung der angeführten Substanzen ermittelt.
Summary Potentiometric investigation of the behavior of resorufin,o-acetylresorufin and ethoxyresorufin revealed the conditions that lead to the formation of semiquinone. The conditions for the titanometric and the stannometric determination of these materials were also established.
Résumé On a établi les conditions de formation d'une hémiquinone, par l'étude potentiométrique du comportement de la résorufine, de l'o-acétylrésomfine et de l'éthoxyrésorufine. On en a déduit les conditions du titrage titanométrique et stannométrique de ces substances.相似文献
982.
983.
Eduard Fron Gerd Schweitzer Josemon Jacob Antoine Van Vooren David Beljonne Klaus Müllen Johan Hofkens Mark Van der Auweraer Frans C De Schryver 《Chemphyschem》2007,8(9):1386-1393
The excited-state properties of two peryleneimide chromophore end-capped pentaphenylene compounds were investigated in detail using femtosecond transient absorption and single-photon timing experiments. Singlet-singlet annihilation was found to promote one chromophore into a higher excited state and results in the formation of an ultra-short-living intermediate charge-transfer (CT) state in the S(n)-S(1) deactivation pathway. In low-polarity solvents, this CT state is found to be energetically higher than the first excited state and thus cannot be populated via one-photon excitation. The observed CT state decays with a time constant of about 1 ps to form the lowest singlet excited state. These results demonstrate the potential use of the singlet-singlet annihilation as a novel tool in studying reactions occurring in states that are energetically above the S(1). 相似文献
984.
Eduard Prugovečki 《Foundations of Physics》1979,9(7-8):575-587
The concept of probability space is generalized to that of stochastic probability space. This enables the introduction of representations of quantum mechanics on stochastic phase spaces. The resulting formulation of quantum statistical mechanics in terms of -distribution functions bears a remarkable resemblance to its classical counterpart. Furthermore, both classical and quantum statistical mechanics can be formulated in one and the same master Liouville space overL
2(). A joint derivation of a classical and quantum Boltzman equation provides an illustration of the practical uses of these formalisms.Supported in part by an NRC grant. 相似文献
985.
Eduard Herlt 《General Relativity and Gravitation》1978,9(8):711-719
This paper shows that a new class of axially symmetric static electrovacuum solutions and the Kerr solution are obtainable from the van Stockum metric. The new class contains an infinite set of asymptotically flat solutions (in closed form), each of which involves an arbitrary set of parameters. The parameters have to be interpreted as functions of massm, chargee, and higher electric multipole moments
i
of the particle. The casee=
i
=0 leads to the Darmois metric. Well-known and new examples are given. 相似文献
986.
Alexey V. Koltsov Eduard V. Prihod’ko Andrey S. Pashinkin Vladimir B. Koltsov 《Monatshefte für Chemie / Chemical Monthly》2006,137(6):693-701
Summary. The proposed modelling of solid/liquid interfacial phenomena consists in relating the main experimental parameter – contact
angle θ for metals or alloys on different substrates to combinations of the interatomic interaction parameters of the phases
in contact. Physically, these interatomic interaction parameters are analogous to the electronic density distribution in the
first and second coordination spheres of the crystallographic lattice of the component, to the bond length, and to the electrochemical
factors. The contact angle θ of some alloys on AlN substrates in the case of non-reactive or reactive wetting is calculated. 相似文献
987.
In this work, the aromatic fluctuation index (FLU) that describes the fluctuation of electronic charge between adjacent atoms in a given ring is introduced as a new aromaticity measure. This new electronic criterion of aromaticity is based on the fact that aromaticity is related to the cyclic delocalized circulation of pi electrons. It is defined not only considering the amount of electron sharing between contiguous atoms, which should be substantial in aromatic molecules, but also taking into account the similarity of electron sharing between adjacent atoms. For a series of rings in 15 planar polycyclic aromatic hydrocarbons, we have found that, in general, FLU is strongly correlated with other widely used indicators of local aromaticity, such as the harmonic-oscillator model of aromaticity, the nucleus independent chemical shift, and the para-delocalization index (PDI). In contrast to PDI, the FLU index can be applied to study the aromaticity of rings with any number of members and it can be used to analyze both the local and global aromatic character of rings and molecules. 相似文献
988.
Karolien De Wael Philippe Westbroek Joost De Strycker Eduard Temmerman 《Microchemical Journal》2004,77(1):85-92
A method is described to detect Cu(II) and Cu(I) added as bromide simultaneously in styrene solution containing tetrahexylammoniumperchloraat (THAP) as supporting electrolyte. It was found that Cu(II) and Cu(I) behave similarly in styrene and in aqueous solution. Reduction of Cu(II) and Cu(I) to metallic copper, as well as oxidation of Cu(I) to Cu(II) and the dissolution of a deposited metallic copper layer are observed. Ohmic drop problems were circumvented by adding THAP to the styrene solution and using ultramicro electrodes. The simultaneous detection of Cu(II) and Cu(I) is based on recording a cyclic voltammetric curve in a mixture of these compounds and calculating their concentration from the cathodic limiting current obtained at −0.80 V vs. RE and the anodic stripping peak corresponding to the dissolution of metallic copper. A detection limit of 2.0×10−4 mol l−1 was obtained for both Cu(II) and Cu(I) and reproducible results were obtained concerning sensitivity and stability of the calibration curves. 相似文献
989.
Il'ya A. Gural'skiy Pavlo V. Solntsev Konstantin V. Domasevitch Eduard B. Rusanov Alexander N. Chernega 《Acta Crystallographica. Section C, Structural Chemistry》2007,63(6):m259-m263
Poly[[μ4‐4,4′‐bipyridazine‐μ5‐sulfato‐disilver(I)] monohydrate], {[Ag2(SO4)(C8H6N4)]·H2O}n, (I), and poly[[aqua‐μ4‐pyridazino[4,5‐d]pyridazine‐μ3‐sulfato‐disilver(I)] monohydrate], {[Ag2(SO4)(C6H4N4)(H2O)]·H2O}n, (II), possess three‐ and two‐dimensional polymeric structures, respectively, supported by N‐tetradentate coordination of the organic ligands [Ag—N = 2.208 (3)–2.384 (3) Å] and O‐pentadentate coordination of the sulfate anions [Ag—O = 2.284 (3)–2.700 (2) Å]. Compound (I) is the first structurally examined complex of the new ligand 4,4′‐bipyridazine; it is based upon unprecedented centrosymmetric silver–pyridazine tetramers with tetrahedral AgN2O2 and trigonal–bipyramidal AgN2O3 coordination of two independent AgI ions. Compound (II) adopts a typical dimeric silver–pyridazine motif incorporating two kinds of square‐pyramidal AgN2O3 AgI ions. The structure exhibits short anion–π interactions involving noncoordinated sulfate O atoms [O...π = 3.041 (3) Å]. 相似文献
990.
Eduard Feireisl 《Mathematical Methods in the Applied Sciences》1992,15(4):287-297
We introduce the concept of exponential attractor for non-autonomous systems. Then we prove the existence and finite dimensionality of the attractor for the model equation where K and f are quasiperiodic in time. 相似文献