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121.
G. Løvhøiden J.R. Lien S. El-Kazzaz J. Rekstad C. Ellegaard J.H. Bjerregaard P. Knudsen P. Kleinheinz 《Nuclear Physics A》1980,339(3):477-502
The level structures of the 145, 147, 149Nd nuclei up to about 5 MeV excitation energy have been investigated with the (3He, α) reaction at 24 MeV. Additional 17 MeV (d, t) data have been obtained for 147, 149Nd. The angular distributions have been analyzed with standard DWBA calculations, and spectroscopic factors have been deduced. Two groups of states carrying h single-particle strength may be associated with the ? [514] and ? [505] Nilsson orbitals. A considerable amount of high-l single-particle strength may be found in the continuum observed in the (3He, α) spectra above 3 MeV in all the nuclei. 相似文献
122.
Details of the reactive processes by which TiC and TiN microclusters are formed from precursor molecules in the gas phase are not clearly understood. We have performed ab initio calculations based on density functional theory methods in order to get some insight into the chemical reactions of precursor molecules. Using microcanonical molecular-dynamics we have simulated scattering processes between molecules consisting of the elements Ti, Cl, N and H. The simulations show that fluctuations of the kinetic energy can be large enough to break up bonds at moderate temperatures. 相似文献
123.
The new [3+3] NH-CH2 bridged cyclophanes bearing different functional groups and different cavity sizes were prepared in one pot by treating diamine derivatives with dialdehyde derivatives. Factors important for efficiently form-ing these macrocycles include reaction concentration (10 or 100?mmol), temperature (room temperature or 40–50?°C) and solvent (CHCl3). Preliminary fluorescence spectrometer and HRMS-ESI studies demonstrated the inner cavity of the new [3+3] NH-CH2 bridged cyclophanes bearing three hydroxyl groups (3c) as a new highly selective probe for the naked eye detection of Ag+ in PBS buffer. 相似文献
124.
Stephan Schrölkamp Alfons Völkl Thomas Lügger F. Ekkehardt Hahn Wolfgang Beck Wolf Peter Fehlhammer Prof. Dr. 《无机化学与普通化学杂志》2008,634(15):2940-2947
Palladium, Platinum, and Diiron Complexes with Isocyanoacetate: Ring Closure, Acid‐Induced Ring Opening, Diprotonation Substitution by isocyanoacetate (CNCH2CO2?) of one chloro ligand in trans‐[MCl2(PPh3)2] (M = Pd, Pt) results in the Δ2‐oxazolin‐5‐on‐2‐ato complexes 4a , b , i.e. immediate cyclization occurs in contact with these metal(II) species. In contrast, the open‐chain form of the functional isocyanide is retained in [K(18‐crown‐6][Fe2Cp2(CNCH2CO2)(CO)3] ( 16 ) in which it occupies a terminal position. Protonation (alkylation) of the platinum complex 4b proceeds with ring cleavage and formation of isocyano acetic acid 11 (ethyl isocyanoacetate 12 ) stabilized by metal ion coordination. Protonation of 16 requires two equivalents of acid to yield the aminocarbyne‐bridged complex [{μ‐C=N(H)CH2CO2H}Fe2Cp2(CO)3](BF4) ( 17 ) as the only isolable product. Here isocyanoacetate displays a third kind of reactivity pattern in addition to that at PdII/PtII and that at Cr0/W0 where the primary species [M(CO)5CNCH2CO2]? and [M(CO)5CNCH2CO2H] proved to be the most stable. All of the proposed structures are substantiated by analytical and the usual spectroscopic (IR, NMR{1H, 13C, 31P}, FAB‐MS) data, that of 4b also by an X‐ray structure determination which reveals a practically perpendicular arrangement of the coordination and the ring plane, and a long C2‐O bond as the predetermined breaking point of the heterocycle. 相似文献
125.
Dr. Dafeng Yan Dr. Chalachew Mebrahtu Prof. Shuangyin Wang Prof. Dr. Regina Palkovits 《Angewandte Chemie (International ed. in English)》2023,62(16):e202214333
Renewable H2 production by water electrolysis has attracted much attention due to its numerous advantages. However, the energy consumption of conventional water electrolysis is high and mainly driven by the kinetically inert anodic oxygen evolution reaction. An alternative approach is the coupling of different half-cell reactions and the use of redox mediators. In this review, we, therefore, summarize the latest findings on innovative electrochemical strategies for H2 production. First, we address redox mediators utilized in water splitting, including soluble and insoluble species, and the corresponding cell concepts. Second, we discuss alternative anodic reactions involving organic and inorganic chemical transformations. Then, electrochemical H2 production at both the cathode and anode, or even H2 production together with electricity generation, is presented. Finally, the remaining challenges and prospects for the future development of this research field are highlighted. 相似文献
126.
Yi Wan Dr. Jianghua He Dr. Yuetao Zhang 《Angewandte Chemie (International ed. in English)》2023,62(8):e202218248
Rapid access to sequence-controlled multi-block copolymers (multi-BCPs) remains as a challenging task in the polymer synthesis. Here we employ a Lewis pair (LP) composed of organophosphorus superbase and bulky organoaluminum to effectively copolymerize the mixture of methacrylate, cyclic acrylate, and two acrylates, into well-defined di-, tri-, tetra- and even a hepta-BCP in one-pot one-step manner. The combined livingness, dual-initiation and CSC feature of Lewis pair polymerization enable us to achieve not only a trihexaconta-BCP with the highest record in 8 steps by using four-component monomer mixture as building blocks, but also the arbitrarily-regulated monomer sequence in multi-BCP, simply by changing the composition and adding order of the monomer mixtures, thus demonstrating the powerful capability of our strategy in improving the efficiency and enriching the composition of multi-BCP synthesis. 相似文献
127.
Chuanshen Du Paul Gregory Dhanush U. Jamadgni Alana M. Pauls Julia J. Chang Rick W. Dorn Andrew Martin E. Johan Foster Aaron J. Rossini Martin Thuo 《Angewandte Chemie (International ed. in English)》2023,62(44):e202308822
Combustion is often difficult to spatially direct or tune associated kinetics—hence a run-away reaction. Coupling pyrolytic chemical transformation to mass transport and reaction rates (Damköhler number), however, we spatially directed ignition with concomitant switch from combustion to pyrolysis (low oxidant). A ‘surface-then-core’ order in ignition, with concomitant change in burning rate,is therefore established. Herein, alkysilanes grafted onto cellulose fibers are pyrolyzed into non-flammable SiO2 terminating surface ignition propagation, hence stalling flame propagating. Sustaining high temperatures, however, triggers ignition in the bulk of the fibers but under restricted gas flow (oxidant and/or waste) hence significantly low rate of ignition propagation and pyrolysis compared to open flame (Liñán's equation). This leads to inside-out thermal degradation and, with felicitous choice of conditions, formation of graphitic tubes. Given the temperature dependence, imbibing fibers with an exothermically oxidizing synthon (MnCl2) or a heat sink (KCl) abets or inhibits pyrolysis leading to tuneable wall thickness. We apply this approach to create magnetic, paramagnetic, or oxide containing carbon fibers. Given the surface sensitivity, we illustrate fabrication of nm- and μm-diameter tubes from appropriately sized fibers. 相似文献
128.
Dr. Yu Harabuchi Dr. Hiroki Hayashi Dr. Hideaki Takano Prof. Tsuyoshi Mita Prof. Satoshi Maeda 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2023,135(1):e202211936
Systematic reaction path exploration revealed the entire mechanism of Knowles's light-promoted catalytic intramolecular hydroamination. Bond formation/cleavage competes with single electron transfer (SET) between the catalyst and substrate. These processes are described by adiabatic processes through transition states in an electronic state and non-radiative transitions through the seam of crossings (SX) between different electronic states. This study determined the energetically favorable SET path by introducing a practical computational model representing SET as non-adiabatic transitions via SXs between substrate's potential energy surfaces for different charge states adjusted based on the catalyst's redox potential. Calculations showed that the reduction and proton shuttle process proceeded concertedly. Also, the relative importance of SET paths (giving the product and leading back to the reactant) varies depending on the catalyst's redox potential, affecting the yield. 相似文献
129.
Qingchun Xu Puning Ren Yang Peng Prof. Nengchao Luo Zhuyan Gao Caixia Meng Jian Zhang Prof. Feng Wang 《Angewandte Chemie (International ed. in English)》2023,62(30):e202301668
Photocatalytic 2-iodoethanol (IEO) coupling provides 1,4-butanediol (BDO) of particular interest to produce degradable polyesters. However, the reduction potential of IEO is too negative (−1.9 vs NHE) to be satisfied by most of the semiconductors, and the kinetics of transferring one electron for IEO coupling is slow. Here we design a catalytic Ni complex, which works synergistically with TiO2, realizing reductive coupling of IEO powered by photo-energy. Coordinating by terpyridine stabilizes Ni2+ from being photo-deposited to TiO2, thereby retaining the steric configuration beneficial for IEO coupling. The Ni complex can rapidly extract electrons from TiO2, generating a low-valent Ni capable of reducing IEO. The photocatalytic IEO coupling thus provides BDO in 72 % selectivity. By a stepwise procedure, BDO is obtained with 70 % selectivity from ethylene glycol. This work put forward a strategy for the photocatalytic reduction of molecules requiring strong negative potential. 相似文献
130.
Cheng Cheng Dr. Wei Ren Fei Miao Xuantong Chen Xiaoxiao Chen Prof. Hui Zhang 《Angewandte Chemie (International ed. in English)》2023,62(10):e202218510
Generating FeIV=O on single-atom catalysts by Fenton-like reaction has been established for water treatment; however, the FeIV=O generation pathway and oxidation behavior remain obscure. Employing an Fe−N−C catalyst with a typical Fe−N4 moiety to activate peroxymonosulfate (PMS), we demonstrate that generating FeIV=O is mediated by an Fe−N−C−PMS* complex—a well-recognized nonradical species for induction of electron-transfer oxidation—and we determined that adjacent Fe sites with a specific Fe1−Fe1 distance are required. After the Fe atoms with an Fe1-Fe1 distance <4 Å are PMS-saturated, Fe−N−C−PMS* formed on Fe sites with an Fe1-Fe1 distance of 4–5 Å can coordinate with the adjacent FeII−N4, forming an inter-complex with enhanced charge transfer to produce FeIV=O. FeIV=O enables the Fenton-like system to efficiently oxidize various pollutants in a substrate-specific, pH-tolerant, and sustainable manner, where its prominent contribution manifests for pollutants with higher one-electron oxidation potential. 相似文献