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11.
Dr. Antony J. Stasyuk Dr. Olga A. Stasyuk Prof. Dr. Miquel Solà Prof. Dr. Alexander A. Voityuk 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(10):2577-2585
Porphyrin–fullerene dyads are promising candidates for organic photovoltaic devices. The electron-transfer (ET) properties of the molecular devices depend significantly on the mutual position of the donor and acceptor. Recently, a new type of molecular isomerism (akamptisomerism) has been discovered. In the present study, we explore how photoinduced ET can be modulated by passing from one akamptisomer to another. To this aim, four akamptisomers of the quinoxalinoporphyrin–[60]fullerene complex are selected for computational study. The most striking finding is that, depending on the isomer, the porphyrin unit in the dyad can act as either electron donor or electron acceptor. Thus, the stereoisomeric diversity allows one to change the direction of ET between the porphyrin and fullerene moieties. To understand the effect of akamptisomerism on the photoinduced ET processes, a detailed analysis of initial and final states involved in the ET is performed. The computed rate for charge separation is estimated to be in the region of 1–10 ns−1. The formation of a long-living quinoxalinoporphyrin anion radical species is predicted. 相似文献
12.
Ethan M. Cunningham Alexander S. Gentleman Peter W. Beardsmore 《Molecular physics》2019,117(21):2990-3000
ABSTRACTWe present the results of a combined experimental and computational study of the structures of gas-phase M+(N2O)n (M?=?Li, Al) complexes. Infrared spectra were recorded in the region of the N2O asymmetric (N?=?N) stretch using photodissociation spectroscopy employing the inert messenger technique. Unlike in our previous studies on M+(N2O)n (M?=?Cu, Ag, Au and M?=?Co, Rh, Ir) complexes, N– and O–bound isomers in this case are near isoenergetic and are not distinguished spectroscopically at this resolution. In the case of Li+ complexes, there is, however, evidence for the presence of bound N2 moieties, indicating the presence of inserted, OLi+N2(N2O)n–type structures. The weak N2 band lies to the blue of the signature of molecularly N– and O–bound ligands and is well–reproduced in the simulated spectra of energetically low-lying structures computed from density functional theory. No such inserted isomers are observed in the case of Al+(N2O)n complexes whose infrared spectra can be understood on the basis of molecularly-bound N2O ligands. The differences in M+(N2O)n structures observed for these closed–shell, ns2, metal centres relative to other metal cations are discussed in terms of the likely bonding motifs. 相似文献
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Maksim Kulichenko Nikita Fedik Prof. Dr. Konstatin V. Bozhenko Prof. Dr. Alexander I. Boldyrev 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(20):5311-5315
Growing demands of material science and, in particular, in the field of nonlinear optics (NLO) encourage us to look for stable highly polarizable molecules with excess diffuse electrons. An unusual class of compounds called electrides comply with these requirements. Many attempts have been made, yet only few electrides have been synthesized as solids and none of them as molecular species. In this paper, a new theoretically designed molecular species with electride characteristics is reported. The idea of this molecular electride comes from the formation of electride-like features in the MgO crystal with defect F-centers. The geometry of the investigated molecule can be described as a Mg4O4 cube with one oxygen atom removed. In Mg4O3, two 3s electrons are pushed out from the inner area of the molecule forming a diffuse electride multicentered bond. Our calculations show that this electride-like cluster possesses a noticeably large first hyperpolarizability β=5733 au. At the same time, a complete cube Mg4O4 and Mg4O32+ without electride electron pair have much smaller β: 0 au and 741 au, respectively. This fact indicates the decisive role of the electride electron pair in NLO properties. Additionally, vertical detachment energies of isomers (VDE), excitation energies ΔE, polarizabilities α, and IR spectra were calculated. These properties, including β, are supposed to be observable experimentally and can serve as indirect evidence of the stable molecular electride formation. 相似文献
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We describe matrices with extremal generalized centralizers over algebraically closed fields. 相似文献
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Magnus Pfaffenbach Dipl.‐Wirtschaftsing. Alexander Roller Prof. Dr. Tanja Gaich 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(25):8444-8447
Herein, we report the synthetically practical, short, and general access to novel indolophane architectures by means of a photochemical C?H activation process—the Witkop cyclization. These highly strained scaffolds were obtained by photoinduced ring closure and feature atropisomerism as well as aromatic ring current effects, which both have been investigated. The prevailing regioselectivity of theWitkop cyclization reaction was completely reversed by the presence of a quaternary carbon center, exerting a strong Thorpe–Ingold effect on the system for which experimental‐evidence is provided. 相似文献
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