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951.
Ultrafast dissipative dynamics of vibrational degrees of freedom in molecular systems in the condensed phase are studied here. Assuming that the total system is separable into a relevant part and a reservoir, the dynamics of the relevant part can be described by means of a reduced statistical density operator. For a weak or intermediate coupling between the relevant part and the reservoir, it is possible to derive a second-order master equation for this operator. Using a representation of the reduced statistical operator in an appropriate molecular basis set, vibrational dynamics in a variety of potential energy surfaces can be studied. In the numerical calculations, we focus on the dissipative dynamics under the influence of external laser fields. In the first example, vibrational wave-packet dynamics and time-resolved pump-probe spectroscopy of molecular systems with nonadiabatically coupled excited-state potential energy surfaces is presented. In the second part, we show how an intense laser field modifies the wave-packet motion onto two radiatively coupled potential energy surfaces. Finally, the controlled preparation of definite vibrational states in a triatomic molecule with infrared laser pulses is considered taking relaxation and dephasing processes into account. © 1996 John Wiley & Sons, Inc. 相似文献
952.
Benjamin May Matthias Lexow Dr. Nicola Taccardi Prof. Dr. Hans-Peter Steinrück Dr. Florian Maier 《ChemistryOpen》2019,8(1):15-22
The reactions of copper, silver, and gold with the imidazolium-based polyhalide ionic liquid (IL) [C6C1Im][Br2I] were investigated by using X-ray photoelectron spectroscopy (XPS), weight-loss measurements, and gas-phase mass spectrometry. All three Group 11 metals are strongly corroded by the IL at moderate temperatures to give a very high content of dissolved CuI, AgI, and AuI species. The IL–metal solutions are stable against contact with water and air. The replacement of imidazolium with inorganic sodium cations decreased metal corrosion rates by orders of magnitude. Our results clearly indicate metal oxidation by iodide from dibromoiodide anions to form molecular iodine and anionic [Br-MI-Br]− (M=Cu, Ag, Au) complexes stabilized by imidazolium counterions. From experiments with a trihalide IL with imidazolium methylated at the 2-position, we ruled out the formation of imidazole–carbene as a cause of the observed corrosion. In contrast to Group 11 metals, molybdenum is inert against the trihalide IL, which is attributed to surface passivation. 相似文献
953.
954.
955.
César A. Urbina-Blanco Safia Z. Jilani Isaiah R. Speight Michael J. Bojdys Tomislav Friščić J. Fraser Stoddart Toby L. Nelson James Mack Renã A. S. Robinson Emanuel A. Waddell Jodie L. Lutkenhaus Murrell Godfrey Martine I. Abboud Stephen O. Aderinto Damilola Aderohunmu Lučka Bibič João Borges Vy M. Dong Lori Ferrins Fun Man Fung Torsten John Felicia P. L. Lim Sarah L. Masters Dickson Mambwe Pall Thordarson Maria-Magdalena Titirici Gabriela D. Tormet-González Miriam M. Unterlass Austin Wadle Vivian W.-W. Yam Ying-Wei Yang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(42):18462-18466
956.
Dr. Nicolas P. Martin Enric Petrus Dr. Mireia Segado Ana Arteaga Dr. Lev N. Zakharov Dr. Carles Bo Dr. May Nyman 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(45):10580-10584
Group V Nb-polyoxometalate (Nb-POM) chemistry generally lacks the elegant pH-controlled speciation exhibited by group VI (Mo, W) POM chemistry. Here three Nb-POM clusters were isolated and structurally characterized; [Nb14O40(O2)2H3]14−, [((UO2)(H2O))3Nb46(UO2)2O136H8(H2O)4]24−, and [(Nb7O22H2)4(UO2)7(H2O)6]22−, that effectively capture the aqueous Nb-POM species from pH 7 to pH 10. These Nb-POMs illustrate a reaction pathway for control over speciation that is driven by counter-cations (Li+) rather than pH. The two reported heterometallic POMs (with UO22+ moieties) are stabilized by replacing labile H2O/HO−Nb=O with very stable O=U=O. The third isolated Nb-POM features cis-yl-oxos, prior observed only in group VI POM chemistry. Moreover, with these actinide-heterometal contributions to the burgeoning Nb-POM family, it now transects all major metal groups of the periodic table. 相似文献
957.
Konshina E. A. Scherbinin D. P. Abboud M. M. Gladskikh I. A. 《Optics and Spectroscopy》2018,125(2):290-292
Optics and Spectroscopy - Spectra of optical density of granulated 2-nm-thick gold films deposited on the surface of thin films of amorphous hydrogenated carbon (a-C:H) on quartz substrates are... 相似文献
958.
959.
Anura P. Dantanarayana Brian Dupre Jesse A. May Vincent M. Lynch 《Journal of heterocyclic chemistry》1999,36(1):65-73
3-(Methoxymethoxymethyl)-2-thiophenesulfonamides and 3-hydroxymethyl-N-methoxymethyl-2-thiophenesulfonamides have been shown to undergo cyclization when treated under anhydrous acidic conditions to provide the novel 2,3-dihydro-5H-thieno[2,3-e]-4,1,2-oxathiazepine ring system. Incorporation of a primary sulfonamide group into position seven of the molecule provided compounds which inhibit human carbonic anhydrase II. 相似文献
960.
F. Grases A. I. Villacampa O. Shnel E. Knigsberger P. M. May 《Crystal Research and Technology》1997,32(5):707-715
The composition of the solid phases precipitating from urine-like liquors has been determined at 37°C over the pH range between 6 and 8 for solutions with varying amounts of magnesium, citrate, oxalate and ammonium ions. At pH ⩽7 hydroxyapatite appeared, either alone or, depending on the magnesium ion concentration, in a mixture with brushite. Stravite and calcium phosphates precipitated at pH ⩾ 7.5. No other phosphate solids were observed to precipitate from these urine-like liquors under physiological conditions. No influence on the nature of the solid phase was exerted by citrate, oxalate or ammonium ions. The variation of solid phase composition caused by changing solution composition is ascribed to kinetic rather than thermodynamic factors. 相似文献