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91.
Vicente J Chicote MT Martínez-Viviente E Martínez-Martínez AJ Jones PG 《Inorganic chemistry》2006,45(26):10434-10436
A trinuclear Pd complex containing a mu3-1,1-ethylenedithiolato ligand has been synthesized and its structure confirmed by X-ray crystallography. It is the first example of a 1,1-ethylenedithiolato complex containing an anionic carbon sigma donor. This compound shows an unprecedented fluxional behavior in solution, by which the three palladacycles exchange around the dithiolene. The activation parameters for this process have been derived by NMR line shape analysis, and a mechanism is proposed. 相似文献
92.
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94.
Channel plasmon-polariton guiding by subwavelength metal grooves 总被引:1,自引:0,他引:1
We report on realization of channel plasmon-polariton (CPP) propagation along a subwavelength metal groove. Using imaging with a near-field microscope and end-fire coupling with a tapered fiber connected to a tunable laser at telecommunication wavelengths (1425-1620 nm), we demonstrate low-loss (propagation length approximately 100 microm) and well-confined (mode width approximately 1.1 microm) CPP guiding along a triangular 0.6 microm-wide and 1 microm-deep groove in gold. We develop a simple model based on the effective-index method that accounts for the main features of CPP guiding and provides a clear physical picture of this phenomenon. 相似文献
95.
A study of BaO has been made by use of thermogravimetric analysis, oxygen concentration analysis, and X-ray lattice parameter measurements in the temperature range 850°C ? T ? 1420°C and oxygen pressure range 7 × 10-6 atm ? pO2 ? 0·820 atm. Both the weight gain by the BaO samples and subsequently determined excess oxygen concentration were found to be directly proportional to . The enthalpy of incorporation oxygen in the lattice was determined to be ?0·395 ± 0·034 eV. Creation of vacancies on cation sites or of oxygen interstitials are consistent with the experimental results. As an alternative, the formation of O22? ions, (as in BaO2) as a result of incorporation of excess oxygen in the lattice, has been suggested. 相似文献
96.
The analytical capabilities of the microminiaturized lab-on-a-valve (LOV) module integrated into a microsequential injection (μSI) fluidic system in terms of analytical chemical performance, microfluidic handling and on-line sample processing are compared to those of the micro total analysis systems (μTAS), also termed lab-on-a-chip (LOC). This paper illustrates, via selected representative examples, the potentials of the LOV scheme vis-à-vis LOC microdevices for environmental assays. By means of user-friendly programmable flow and the exploitation of the interplay between the thermodynamics and the kinetics of the chemical reactions at will, LOV allows accommodation of reactions which, at least at the present stage, are not feasible by application of microfluidic LOC systems. Thus, in LOV one may take full advantage of kinetic discriminations schemes, where even subtle differences in reactions are utilized for analytical purposes. Furthermore, it is also feasible to handle multi-step sequential reactions of divergent kinetics; to conduct multi-parametric determinations without manifold reconfiguration by utilization of the inherent open-architecture of the micromachined unit for implementation of peripheral modules and automated handling of a variety of reagents; and most importantly, it offers itself as a versatile front end to a plethora of detection schemes. Not the least, LOV is regarded as an emerging downscaled tool to overcome the dilemma of LOC microsystems to admit real-life samples. This is nurtured via its intrinsic flexibility for accommodation of sample pre-treatment schemes aimed at the on-line manipulation of complex samples. Thus, LOV is playing a prominent role in the environmental field, whenever the monitoring of trace level concentration of pollutants is pursued, because both matrix isolation and preconcentration of target analytes is most often imperative, or in fact necessary, prior to sample presentation to the detector. 相似文献
97.
Prof. Carl Redshaw Mark Walton Dr. Lucy Clowes Dr. David L. Hughes Dr. Anna‐Marie Fuller Dr. Yimin Chao Dr. Alex Walton Dr. Victor Sumerin Dr. Pertti Elo Dr. Igor Soshnikov Dr. Weizhen Zhao Prof. Wen‐Hua Sun 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(27):8884-8899
The reactions of MCl5 or MOCl3 with imidazole‐based pro‐ligand L1H, 3,5‐tBu2‐2‐OH‐C6H2‐(4,5‐Ph2‐1H‐)imidazole, or oxazole‐based ligand L2H, 3,5‐tBu2‐2‐OH‐C6H2(1H‐phenanthro[9,10‐d])oxazole, following work‐up, afforded octahedral complexes [MX(L1, 2)], where MX=NbCl4 (L1, 1 a ; L2, 2 a ), [NbOCl2(NCMe)] (L1, 1 b ; L2, 2 b ), TaCl4 (L1, 1 c ; L2, 2 c ), or [TaOCl2(NCMe)] (L1, 1 d ). The treatment of α‐diimine ligand L3, (2,6‐iPr2C6H3N?CH)2, with [MCl4(thf)2] (M=Nb, Ta) afforded [MCl4(L3)] (M=Nb, 3 a ; Ta, 3 b ). The reaction of [MCl3(dme)] (dme=1,2‐dimethoxyethane; M=Nb, Ta) with bis(imino)pyridine ligand L4, 2,6‐[2,6‐iPr2C6H3N?(Me)C]2C5H3N, afforded known complexes of the type [MCl3(L4)] (M=Nb, 4 a ; Ta, 4 b ), whereas the reaction of 2‐acetyl‐6‐iminopyridine ligand L5, 2‐[2,6‐iPr2C6H3N?(Me)C]‐6‐Ac‐C5H3N, with the niobium precursor afforded the coupled product [({2‐Ac‐6‐(2,6‐iPr2C6H3N?(Me)C)C5H3N}NbOCl2)2] ( 5 ). The reaction of MCl5 with Schiff‐base pro‐ligands L6H–L10H, 3,5‐(R1)2‐2‐OH‐C6H2CH?N(2‐OR2‐C6H4), (L6H: R1=tBu, R2=Ph; L7H: R1=tBu, R2=Me; L8H: R1=Cl, R2=Ph; L9H: R1=Cl, R2=Me; L10H: R1=Cl, R2=CF3) afforded [MCl4(L6–10)] complexes (M=Nb, 6 a – 10 a ; M=Ta, 6 b – 9 b ). In the case of compound 8 b , the corresponding zwitterion was also synthesised, namely [Ta?Cl5(L8H)+] ? MeCN ( 8 c ). Unexpectedly, the reaction of L7H with TaCl5 at reflux in toluene led to the removal of the methyl group and the formation of trichloride 7 c [TaCl3(L7‐Me)]; conducting the reaction at room temperature led to the formation of the expected methoxy compound ( 7 b ). Upon activation with methylaluminoxane (MAO), these complexes displayed poor activities for the homogeneous polymerisation of ethylene. However, the use of chloroalkylaluminium reagents, such as dimethylaluminium chloride (DMAC) and methylaluminium dichloride (MADC), as co‐catalysts in the presence of the reactivator ethyl trichloroacetate (ETA) generated thermally stable catalysts with, in the case of niobium, catalytic activities that were two orders of magnitude higher than those previously observed. The effects of steric hindrance and electronic configuration on the polymerisation activity of these tantalum and niobium pre‐catalysts were investigated. Spectroscopic studies (1H NMR, 13C NMR and 1H? 1H and 1H? 13C correlations) on the reactions of compounds 4 a / 4 b with either MAO(50) or AlMe3/[CPh3]+[B(C6F5)4]? were consistent with the formation of a diamagnetic cation of the form [L4AlMe2]+ (MAO(50) is the product of the vacuum distillation of commercial MAO at +50 °C and contains only 1 mol % of Al in the form of free AlMe3). In the presence of MAO, this cationic aluminium complex was not capable of initiating the ROMP (ring opening metathesis polymerisation) of norbornene, whereas the 4 a / 4 b systems with MAO(50) were active. A parallel pressure reactor (PPR)‐based homogeneous polymerisation screening by using pre‐catalysts 1 b , 1 c , 2 a , 3 a and 6 a , in combination with MAO, revealed only moderate‐to‐good activities for the homo‐polymerisation of ethylene and the co‐polymerisation of ethylene/1‐hexene. The molecular structures are reported for complexes 1 a – 1 c , 2 b , 5 , 6 a , 6 b, 7 a, 8 a and 8 c . 相似文献