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151.
Haruhiko Ito Katsuaki Koshimura Saori Onitsuka Kohtaro Okada Tsuneo Suzuki Hiroki Akasaka Hidetoshi Saitoh 《Plasma Chemistry and Plasma Processing》2012,32(2):231-248
The dissociative excitation reaction of C2H2 with the electron-cyclotron resonance plasma of Ar was investigated based on the electrostatic-probe measurements and on
the optical emission spectroscopy of the CH(A2Δ–X2Π) transition. The density, n
e, and the temperature, T
e, of free electrons were controlled by adding H2O molecules externally into the reaction region, and the dependence of the CH(A2Δ–X2Π) emission intensity on the addition of H2O was observed to compare with the evaluated dependencies based on n
e and T
e. The mechanism of production of CH(A2Δ) was found, predominantly, to be the electron impact with the contribution of 10–20% of the electron-impact dissociation
of C2H radicals; the contribution of the ion–electron recombination was negligible. Hydrogenated amorphous carbon films were fabricated
using the same reaction system. The atomic compositions, Raman spectra, and the hardness of films were discussed in terms
of the variations of n
e and T
e upon the addition of H2O molecules. 相似文献
152.
153.
Rudolf M Wolfrum S Guldi DM Feng L Tsuchiya T Akasaka T Echegoyen L 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(17):5136-5148
In recent years, endohedral metallofullerenes have attracted tremendous interest not only in physics and chemistry, but also in interdisciplinary areas, such as materials and biological sciences. In this concept article we highlight recent results on different endohedral metallofullerenes based on lanthanides and their derivatives. The chemical and excited state reactivities of endohedral metallofullerenes are discussed for various endohedral clusters. Most important is the part that covers spectroscopic and kinetic assays of reductive and oxidative charge transfer evolving from photoexcited electron donors and electron acceptors, respectively, in a variety of electron donor-acceptor conjugates. Towards this end, we refer to the applications of endohedral metallofullerenes in photovoltaic devices that feature greater efficiency than devices fabricated with empty fullerenes. Herein, we focus mainly on results obtained in the groups of Akasaka, Echegoyen, and Guldi. 相似文献
154.
Abstract Absorption and cmission spectroscopies, which are widely utilized by chemists, can be classified as one–photon spectroscopy. A molecule is excited from its ground state of energy E0 to thc excited state of Ee by the absorption of one photon of frequency given by the Bohr's condition (hω=Ee-E0). The reverse transition is accompanied by the emission of one photon of the same frcquency. Therefore, the molecular state energies can be directly obtained by the photon encrgies absorbed or emitted. Infrared, microwave, electronic absorption, and emission spectroscopies belong to this category of one–photon spectroscopy. 相似文献
155.
Feng L Rudolf M Wolfrum S Troeger A Slanina Z Akasaka T Nagase S Martín N Ameri T Brabec CJ Guldi DM 《Journal of the American Chemical Society》2012,134(29):12190-12197
The potential of Lu(3)N@C(80) and its analogues as electron acceptors in the areas of photovoltaics and artificial photosynthesis is tremendous. To this date, their electron-donating properties have never been explored, despite the facile oxidations that they reveal when compared to those of C(60). Herein, we report on the synthesis and physicochemical studies of a covalently linked Lu(3)N@C(80)-perylenebisimide (PDI) conjugate, in which PDI acts as the light harvester and the electron acceptor. Most important is the unambiguous evidence--in terms of spectroscopy and kinetics--that corroborates a photoinduced electron transfer evolving from the ground state of Lu(3)N@C(80) to the singlet excited state of PDI. In stark contrast, the photoreactivity of a C(60)-PDI conjugate is exclusively governed by a cascade of energy-transfer processes. Also, the electron-donating property of the Lu(3)N@C(80) moiety was confirmed through constructing and testing a bilayer heterojunction solar cell device with a PDI and Lu(3)N@C(80) derivative as electron acceptor and electron donor, respectively. In particular, a positive photovoltage of 0.46 V and a negative short circuit current density of 0.38 mA are observed with PDI/Ca as anode and ITO/Lu(3)N@C(80) as cathode. Although the devices were not optimized, the sign of the V(OC) and the flow direction of J(SC) clearly underline the unique oxidative role of Lu(3)N@C(80) within electron donor-acceptor conjugates toward the construction of novel optoelectronic devices. 相似文献
156.
A new diphosphine (POP) ligand bearing an alkoxide group allows us to synthesize partially fluorinated arenes. A nickel-catalyzed cross-coupling between a polyfluoroarene and an organozinc reagent in the presence of POP selectively produces a monosubstitution product. Aryl and alkylzinc reagents smoothly take part in the reaction. It is speculated that monosubstitution is the result of accelerated product expulsion from the product/catalyst complex. 相似文献
157.
An ortho-arylation reaction of aromatic imines with aryl chlorides has been achieved using a cobalt-N-heterocyclic carbene catalyst in combination with a neopentyl Grignard reagent. The reaction takes place at room temperature to afford biaryl products in moderate to good yields. 相似文献
158.
Masahiro Kako Yuki Arikawa Shinji Kanzawa Michio Yamada Yutaka Maeda Makoto Furukawa Takeshi Akasaka 《Helvetica chimica acta》2019,102(5)
The reactions of novel S‐heterocyclic carbenes (SHCs), which were prepared by the cycloaddition of disilenes and digermenes to CS2, with C60 and Sc3N@Ih‐C80 afforded the corresponding methano‐bridged fullerenes. The [6,6]‐closed and [6,6]‐open structures were characterized for the SHC adducts of C60 and Sc3N@Ih‐C80, respectively. These derivatives exhibited relatively low oxidation potentials, indicative of the electron‐donating effects of the SHC addends. The electronic properties of the SHC derivatives were clarified by the density functional theory calculations. 相似文献
159.
160.
Marc Rudolf Olga Trukhina Josefina Perles Lai Feng Takeshi Akasaka Tomas Torres Dirk M. Guldi 《Chemical science》2015,6(7):4141-4147
Two subphthalocyanine–C60 conjugates have been prepared by means of the 1,3-dipolar cycloaddition reaction of (perfluoro) or hexa(pentylsulfonyl) electron deficient subphthalocyanines to C60. Comprehensive assays regarding the electronic features – in the ground and excited state – of the resulting conjugates revealed energy and electron transfer processes upon photoexcitation. Most important is the unambiguous evidence – in terms of time-resolved spectroscopy – of an ultrafast oxidative electron transfer evolving from C60 to the photoexcited subphthalocyanines. This is, to the best of our knowledge, the first case of an intramolecular oxidation of C60 within electron donor–acceptor conjugates by means of only photoexcitation. 相似文献