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131.
Hellfried Karpf Oskar E. Polansky Maximilian Zander 《Monatshefte für Chemie / Chemical Monthly》1981,112(5):659-667
The photoDiels-Alder reaction of maleic anhydride with chrysene yields chryseno[4,5-efg]isobenzofuran-4,6-dion (VI). Heavy atom experiments using xenon as an external perturber show that the reaction occurs via the lowest singlet excited state of chrysene. Hydrogen is abstracted from the primaryDiels-Alder adduct IV by the solvent CH2Cl2 possibly in a two-step mechanism. The reaction presents a new type of photoreaction, its mechanism possibly follows a scheme not considered so far in photochemistry.
1,4-Photoaddition von Maleinsäureanhydrid an Chrysen
Zusammenfassung Die Photo-Diels-Alder-Reaktion von Maleinsäureanhydrid mit Chrysen ergibt Chryseno[4,5-efg]-isobenzofuran-4,6-dion (VI). Schweratomexperimente mit Xenon als äußerer Störer zeigen, daß die Reaktion vom niedrigst angeregten Singulettzustand des Chrysens ausgeht. Die Abstraktion von Wasserstoffatomen aus dem primärenDiels-Alder-Addukt IV durch das Lösungsmittel CH2Cl2 folgt möglicherweise einem Zweistufenmechanismus. Die Reaktion stellt einen neuen Typ von Photoreaktion dar; möglicherweise folgt sie einem Mechanismus, der in der Photochemie neuartig ist.相似文献
132.
133.
In this study, we present the synthesis of 5-(3,5-dinitro-1H-pyrazol-4-yl)-1H-tetrazole and its energetic derivatives starting from 4-amino-3,5-dinitropyrazole, which was diazotized and cyanide substituted. A subsequent cycloaddition reaction with sodium azide led to 5-(3,5-dinitro-1H-pyrazol-4-yl)-1H-tetrazole ( 3 ). Several alkaline metal and nitrogen-rich salts were prepared and characterized by low-temperature X-ray diffraction. Additionally, all compounds were analyzed by vibrational spectroscopy (IR), 1H, 13C and 14N NMR spectroscopy, elemental analysis and differential thermal analysis (DTA). Additionally, the heats of formation for selected compounds were calculated using the atomization method based on CBS-4M enthalpies as well as important detonation parameters by using the EXPLO5 code (V6.05). Furthermore, the sensitivities of 3 and all synthesized salts toward friction, impact and electrostatic discharge according to BAM (Bundesamt für Materialforschung) were determined and compared to RDX. 相似文献
134.
135.
Samantha M. Clarke Dr. James P. S. Walsh Dr. Maximilian Amsler Dr. Christos D. Malliakas Dr. Tony Yu Prof. Stefan Goedecker Dr. Yanbin Wang Prof. Chris Wolverton Prof. Danna E. Freedman 《Angewandte Chemie (International ed. in English)》2016,55(43):13446-13449
A new intermetallic compound, the first to be structurally identified in the Cu?Bi binary system, is reported. This compound is accessed by high‐pressure reaction of the elements. Its detailed characterization, physical property measurements, and ab initio calculations are described. The commensurate crystal structure of Cu11Bi7 is a unique variation of the NiAs structure type. Temperature‐dependent electrical resistivity and heat capacity measurements reveal a bulk superconducting transition at Tc=1.36 K. Density functional theory calculations further demonstrate that Cu11Bi7 can be stabilized (relative to decomposition into the elements) at high pressure and temperature. These results highlight the ability of high‐pressure syntheses to allow for inroads into heretofore‐undiscovered intermetallic systems for which no thermodynamically stable binaries are known. 相似文献
136.
Ferhat Can Özkaya Weaam Ebrahim Maximilian Klopotowski Zhen Liu 《Natural product research》2018,32(7):840-843
The anti-neuroinflammatory meroterpenoid citreohybridonol was isolated for the first time from a sponge-derived fungus Penicillium atrovenetum. In this study, in addition to isolation and structure featuring, its unambiguous absolute configuration was determined exclusively by single crystal X-ray diffraction. The C-17-keto tautomer was clearly observed in X-ray analysis. The substance crystallises in the monoclinic space group P21 with a = 10.7496(5) Å, b = 14.3286(7) Å, c = 17.4909(8) Å, β = 103.235(2)°, V = 2622.5(2) Å3, Z = 2, Dcalcd = 1.280 g/cm3. The chirality of the asymmetric carbon atoms was as follows: C3 (S), C5 (R), C6 (S), C8 (S), C9 (R), C10 (R), C13 (R), C14 (R). 相似文献
137.
Dr. Norbert Szimhardt Maximilian H. H. Wurzenberger Lukas Zeisel Michael S. Gruhne Marcus Lommel Prof. Dr. Thomas M. Klapötke Dr. Jörg Stierstorfer 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(8):1963-1974
This unique complex study describes two isomeric aminotriazoles as auspicious nitrogen-rich ligands for energetic coordination compounds (ECCs) to replace the commonly used highly poisonous and environmentally harmful lead-based primary explosives. The triazoles were obtained by easily scalable and convenient synthetic routes starting solely from commercially available starting materials. 1-Amino-1,2,3-triazole ( 1 , 1-ATRI) and, for the first time, 1-amino-1,2,4-triazole ( 2 , 1A-1,2,4-TRI) were employed as ligands to form highly energetic transition-metal(II) complexes. The desired characteristics could be altered successively by using various nonpoisonous metal(II) centers (Cu2+, Mn2+, Fe2+, and Zn2+) and anions (Cl−, NO3−, ClO3−, ClO4−, picrate, styphnate, 2,4,6-trinitro-3-hydroxyphenolate, and 2,4,6-trinitro-3,5-dihydroxyphenolate). The 14 synthesized coordination compounds were characterized comprehensively by XRD, IR and UV/Vis spectroscopy, elemental analysis, and differential thermal and thermogravimetric analyses. Ball-drop impact, electrostatic discharge (ESD), and mechanical (impact and friction) sensitivities were determined according to BAM standard methods. In addition to laser ignition experiments, selected ECCs were evaluated in classical secondary explosive initiation tests (detonators filled with pentaerythritol tetranitrate (nitropenta)), which revealed their enormous potential and proved them to be very attractive for future applications in explosives. 相似文献
138.
Prof. Dr. Wolfgang Petz Dr. Istemi Kuzu Prof. Dr. Gernot Frenking Dr. Diego M. Andrada Prof. Dr. Bernhard Neumüller Maximilian Fritz Jörn E. Münzer 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(25):8536-8546
This work reports the syntheses and the first crystal structures of the cationic carbone adducts [FC(PPh3)2]+ and [BrC(PPh3)2]+ and the protonated dication [FC(H)(PPh3)2]2+, which are derived from the carbone C(PPh3)2. Quantum chemical calculations and bonding analyses were carried out for the series of cations [AC(PPh3)2]+ and dications [AC(H)(PPh3)2]2+, where A=H, Me, F, Cl, Br, I. The bonding analysis suggests that the cations are best described as phosphane complexes L→(CA)+←L (L=PPh3), which are related to the neutral borylene adducts L→(BA)←L (L=cyclic carbene; A=H, aryl) that were recently isolated. The carbone adducts [AC(PPh3)2]+ possess a π electron lone pair at carbon and they can easily be protonated to the dications [AC(H)(PPh3)2]2+. The calculations of the dications indicate that the molecules are best represented as complexes L→(CHA)2+←L (L=PPh3) where a carbene dication is stabilized by the ligands. The central carbon atom in the cations and even in the dications carries a negative partial charge, which is larger than the negative charge at fluorine. There is also the peculiar situation in which the carbon–fluorine bonds in [FC(PPh3)2]+ and [FC(H)(PPh3)2]2+ exhibit the expected polarity with the negative end at fluorine, but the carbon atom has a larger negative charge than fluorine. Given the similarity of carbodiphosphorane C(PPh3)2 and carbodicarbene C(NHC)2, we expect that analogous compounds [AC(NHC)2]+ and [AC(H)(NHC)2]2+ with similar features as [AC(PPh3)2]+ and [AC(H)(PPh3)2]2+ can be isolated. 相似文献
139.
Murty A.R.C. Bulusu Peter Waldstätten Gerhard Schulz Maximilian Grassberger 《Tetrahedron letters》2004,45(12):2523-2526
Irradiation of ascomycin 1a and its derivatives in MeOH, EtOH and propanol resulted in alkoxylation of the pipecolic acid moiety in the ε-position with concomitant reduction in the tricarbonyl region leading to 6-alkoxy-9-hydroxy derivatives in high stereoselectivities and good yields. The products, after reoxidation of the C(9)-OH, afforded the 6-alkoxy analogues of the parent compounds. Elimination of MeOH from the photoproducts, followed by oxidation gave the corresponding 5,6-dehydro amino acid analogues. Similarly, starting from the proline analogue 7 modifications in the pyrrolidine moiety could be achieved. 相似文献
140.
Sonja Fuchs Arumugam Jayaraman Ivo Krummenacher Laura Haley Marta Batovanovi Maximilian Fest Krzysztof Radacki Holger Helten Holger Braunschweig 《Chemical science》2022,13(10):2932
We report that the outcome of the tin–boron exchange reaction of a mixed thiophene-benzo-fused stannole with aryldibromoboranes is associated with the steric bulk of the aryl substituent of the borane reagent, leading to either boroles or large diboracycles as products. NMR spectroscopic studies indicate that the two products can reversibly interconvert in solution, and mechanistic density functional theory (DFT) calculations reveal boroles to be intermediates in the formation of the diboracyclic products. The addition of Lewis bases to the diboracycles leads to the corresponding borole adducts, demonstrating that they react as “masked” boroles. Additionally, the reaction of the title compounds with a series of organic azides affords complex heteropropellanes, formally 2 : 1 borole-azide adducts, that deviate from the usual BN aromatic compounds formed via nitrogen atom insertion into the boroles.Diboramacrocycles are a new form of borole dimers, participating in various addition reactions as “masked” boroles. The reaction of a less crowded diboramacrocycle with organic azides affords unprecedented complex heteropropellanes. 相似文献