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101.
Reinemann DN Wright AM Wolfe JD Tschumper GS Hammer NI 《The journal of physical chemistry. A》2011,115(24):6426-6431
N-methyliminodiacetic acid (MIDA)-protected boronate esters are a new class of reagents that offer great promise in iterative Suzuki-Miyaura cross-coupling reactions. Compared to earlier reagents, MIDA esters are easily handled and are benchtop stable under air indefinitely. The success of this new species is tied to its unique molecular architecture. Compared to the simpler B-N containing molecules ammonia borane and trimethylamine borane, MIDA esters are much larger, and the sp(3) hybridized boron atom is secured by two five membered rings, making this molecular class stable for spectroscopic study. Here, we present infrared, Raman, and surface enhanced Raman (SERS) spectra of methylboronic acid MIDA ester. Comparisons of the spectroscopic results to those from electronic structure calculations suggest that the B-N stretching mode in this molecule lies in the range 560-650 cm(-1), making it among the lowest energy vibrations observed to date that can be primarily attributed to B-N stretching. 相似文献
102.
Alberola A Carter E Constantinides CP Eisler DJ Murphy DM Rawson JM 《Chemical communications (Cambridge, England)》2011,47(9):2532-2534
The β-sheet structure associated with chlorinated aromatics (d(Cl···Cl)≈ 4.0 ?) has been implemented to drive formation of π-stacked structures of dithiadiazolyl radicals. Both title compounds exhibit an increase in paramagnetism above 150 K but solid-state EPR studies indicate that the origin of the paramagnetism in these two systems is different. 相似文献
103.
Rodica Olar Mihaela Badea Dana Marinescu Larisa Calu Cristina Bucur 《Journal of Thermal Analysis and Calorimetry》2011,105(2):571-575
Novel complexes of type [M2LCl4]·nH2O ((1) M:Ni, n = 5; (2) M:Cu, n = 0 and (3) M:Zn, n = 2; L: ligand resulted from 1,2-phenylenediamine, 3,6-diazaoctane-1,8-diamine and formaldehyde template condensation) were
synthesised and characterised. The features of complexes have been assigned from microanalytical, IR and UV–Vis data. The
thermal analyses have evidenced the thermal intervals of stability and also the thermodynamic effects that accompany them.
Processes as water or hydrochloric acid elimination as well as oxidative degradation of the organic ligand were observed.
Complexes display a different thermal behaviour as result of dissimilar chemical interaction of metal ions with chloride anions.
The final product of decomposition was metal(II) oxide as powder X-ray diffraction indicated. 相似文献
104.
Mihaela Badea Rodica Olar Valentina Uivarosi Dana Marinescu Victoria Aldea Stefania Felicia Barbuceanu George Mihai Nitulescu 《Journal of Thermal Analysis and Calorimetry》2011,105(2):559-564
Two new complexes having general formula VOL2·nH2O [(1) L: 5-hydroxyflavone, n = 1; (2) L: chrysin, n = 4] were synthesized and characterized. Based on IR and electronic data we concluded that studied flavones act as bidentate
ligands in complexes with metallic ion coordinated in a square-pyramidal stereochemistry. The thermal analysis (TG, DTA) elucidated
the composition and also the number and nature of the water molecules. The thermal behavior also indicated strong interactions
between oxovanadium (IV) and these oxygen donor ligands. 相似文献
105.
Barbatti M Aquino AJ Szymczak JJ Nachtigallová D Lischka H 《Physical chemistry chemical physics : PCCP》2011,13(13):6145-6155
Deactivation of UV-excited cytosine is investigated by non-adiabatic dynamics simulations, optimization of conical intersections, and determination of reaction paths. Quantum chemical calculations are performed up to the MR-CISD level. Dynamics simulations were performed at multiconfigurational level with the surface hopping method including four electronic states. The results show the activation of four distinct reaction pathways at two different subpicosecond time scales and involving three different conical intersections. Most trajectories relax to a minimum of the S(1) state and deactivate with a time constant of 0.69 ps mainly through a semi-planar conical intersection along the n(O)π* surface. A minor fraction deactivate along ππ* regions of the S(1) surface. Sixteen percent of trajectories do not relax to the minimum and deactivate with a time constant of only 13 fs. 相似文献
106.
Ioana Diaconu Hassan Y. Aboul-Enein Mohammed A. Al-Omar Gheorghe Nechifor Elena Ruse Andrei A. Bunaciu Eugenia Eftimie Totu 《Arabian Journal of Chemistry》2011,4(1):99-103
The paper presents experimental data obtained in the study of liquid–liquid partition equilibriums in biphasic system in order to optimize the process of transport through bulk liquid membranes (triphasic partition systems). The partition equilibriums of some nitrophenols using chloroform as extraction solvent and membranary solvent, respectively, were studied. The influence of the pH on the partition equilibriums was investigated. The repartition constants and the pKa values of the studied nitrophenols were calculated. Nitrophenols were transferred in triphasic system from a feed phase with pH 2, through a chloroform liquid membrane, into a receiving phase with pH 12, with efficiencies over 90%. 相似文献
107.
Joseph K. Rugutt Nikolaus H. Fischer Marcus A. Nauman Thomas J. Schmidt Dana K. Berner 《光谱学快报》2013,46(5):799-818
The two known cadinanes 2-hydroxy-8α-hydroxycalamenene and 2-hydroxy-8α-angeloyloxycalamenene were isolated from a Louisiana population of Heterotheca subaxillaris. Their 13C NMR spectra were fully assigned by the application of HETCOR, COLOC, COSY, NOESY and DEPT experiments. It was shown on the basis of NOESY experiments that both cadinanes require revision at the stereogenic centre C-7. 相似文献
108.
Cun Zhu Rui Deng Jie Zeng Gamal E. Khalil Dana Dabiri Zhongze Gu Younan Xia 《Particle & Particle Systems Characterization》2013,30(6):542-548
A facile approach to the synthesis of pressure and temperature dual‐responsive polystyrene (PS) microbeads with controlled sizes via dispersion polymerization is described. Three different luminophors are selected and directly introduced into the reaction system and thus incorporated into the resultant PS microbeads during polymerization. By manipulating the reaction conditions, including concentrations of the initiator and monomer, polarity of the reaction medium, and injection rate for the monomer, uniform PS microbeads with sizes ranging from 1 to 5 μm are obtained. When a light source centered at 365 nm is used to excite all the luminophors in the PS beads, three distinct and resolvable emission peaks corresponding well with the luminophors are observed. By taking advantage of their sensitive responses to both pressure and temperature, the PS beads can be utilized for quantitative measurements of these two stimulations simultaneously. The PS beads loaded with multiple luminophors have the ability to serve as building blocks for the fabrication of novel sensing and imaging devices and therefore provide a promising strategy for the study of aerodynamics. 相似文献
109.
Finite equilibrated 2-generated 2-groups 总被引:2,自引:0,他引:2
Gheorghe Silberberg 《Acta Mathematica Hungarica》2006,110(1-2):23-35
110.
D. Boudjaadar V. Dana G. Guelachvili X. Thomas 《Journal of Molecular Spectroscopy》2006,238(1):108-117
Using Fourier-transform spectra and a multispectrum fitting procedure, 124 absolute line intensities of 12C16O2 are obtained for the cold band 30011-00001 and the hot band 01131-01101 between 6460 and 6950 cm−1. Vibrational transition dipole moments squared and Herman-Wallis coefficients are reported for each band. Cross comparisons made with previous experimental results and with data available in the HITRAN and Carbon Dioxide Spectroscopic Databank (CDSD), bring some confidence on the good level of accuracy of the present results. Motivated by the demanding needs of some atmospheric experiments dedicated to the survey of the carbon cycle, an additional evaluation of potential absolute line intensity measurement limit is also performed on recently published carbon dioxide absolute line intensity independent measurements. These are obtained in two different laboratories on the bands 30013-00001 and 30012-00001 both located in the 1.6 μm spectral window. It is shown that Fourier-transform experimental CO2 line intensity determination is approaching the challenging required figure of about 0.3% accuracy needed for the survey of the atmospheric carbon cycle. 相似文献