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71.
72.
Ioannis Giannikos Elia El-Darzi Patrick Lees 《The Journal of the Operational Research Society》1995,46(6):713-720
This paper investigates the problem of allocating office space to members of staff in an academic institution. We identify several conflicting objectives and formulate an integer pre-emptive goal programming model to address them. Using data from a pilot site of the University of Westminster, UK, we then experiment with alternative rankings of the objectives. Finally, given the plans to consolidate the activities of this university into fewer sites and the resulting need to relocate some staff members, we discuss how this model can be used to ensure that this process is carried out with the least possible inconvenience. 相似文献
73.
M.A. Koshelev M.Y. Tretyakov R.M. Lees L.-H. Xu 《Applied physics. B, Lasers and optics》2006,85(2-3):273-277
Nitrogen and oxygen pressure broadening parameters for seven r
P(J”,0) transitions of the ν1+ν3 overtone band of the main isotope of ammonia with J” varied from 2 to 9 have been measured at room temperature using an external cavity tunable diode laser spectrometer. Air-broadening parameters have also been calculated from the N2 and O2 measurements. The results are compared to previous measurements in the ν1, ν2, ν3, ν4 and ν1+ν3 bands and to the parameters for the ν3 band that are reported in the HITRAN database. PACS 33.70.Jg; 33.70.-W; 33.20.Ea; 42.62.Fi; 42.68.Ca 相似文献
74.
D. Decamp B. Deschizeaux C. Goy J. -P. Lees M. -N. Minard R. Alemany J. M. Crespo M. Delfino E. Fernandez V. Gaitan et al. 《Zeitschrift fur Physik C Particles and Fields》1992,54(1):75-85
This paper describes a study of Bose-Einstein correlations made using the ALEPH detector at LEP. The correlations are found to enhance the two particle differential cross section for pairs of identical pions by a factor which can be roughly parametrized byR(Q)=1+ exp(-Q22), whereQ is the difference in the 3-momenta of the two pions in their centre of mass frame, =0.51±0.04±0.11 and =3.3±0.2±0.8 GeV–1, which corresponds to a source size of 0.65±0.04±0.16 fm. The large systematic errors on these results reflect their strong dependence on the choice of the reference sample used in the analysis. This problem is believed to occur primarily because of uncertainties in the rates of resonance production and a lack of knowledge about the pion-pion strong interaction. No significant correlations are seen amongst like-charged pion-kaon pairs.Supported by CAICYT, Spain 相似文献
75.
G. R. Sudhakaran J. C. Sarker R. L. Bhattacharjee L. H. Johnston I. Mukhopadhyay R. M. Lees 《International Journal of Infrared and Millimeter Waves》1990,11(4):505-517
Laser Stark spectra have been observed for CD3OH and13CH3OH using the 311 m line of the HCN laser. The spectra were taken for both parallel and perpendicular polarizations up to 60,000 Volts/cm. For CD3OH, the two characteristic structures in the spectra have been identified as the JK=144133, A± doublet in the vt=0 torsional state. For13CH3OH, the low field structure observed is assigned as JK=153142, A– in the vt=0 torsional state. 相似文献
76.
Gough JD Williams RH Donofrio AE Lees WJ 《Journal of the American Chemical Society》2002,124(15):3885-3892
The traditional method for in vitro folding of disulfide-containing proteins is slow and involves a redox buffer of glutathione and glutathione disulfide. To increase the folding rate and to gain insight into the folding process, we replaced glutathione, an aliphatic thiol, with a commercially available aromatic thiol, 4-mercaptobenzeneacetate (1). Aromatic thiol 1 was selected due to its enhanced nucleophilicity and its enhanced leaving-group ability relative to glutathione at pH 7.7. To demonstrate the advantages of 1, the folding of reduced and scrambled RNase A at pH 7.0 and 7.7 in the presence of 1 and glutathione was investigated. For each set of folding conditions, the optimum concentration of each thiol was initially determined and then the folding rates in the presence of each thiol were measured concurrently. In all cases examined, the folding rate enhancement with the aromatic thiol was 5- 6-fold. Furthermore, under similar conditions folding rates were almost identical with either reduced or scrambled RNase A. In addition the 5-6-fold folding rate enhancement varied only slightly with pH, 7.0 vs 7.7. 相似文献
77.
78.
A simple method is described for the preparation of pure, dry alcohols, tritiated in the hydroxyl group. The polymerization of acrylonitrile initiated by tetrakis(dimethylamido)titanium(IV) has been terminated by quenching with tritiated isopropanol at varying reaction times, and the radioactivity of the polymer has been determined, in order to measure the concentration of metal-polymer bonds present in the reaction. The results indicate that about 97 per cent of the polymer present has been terminated by a reaction leading to detachment of the polymer chain from the metal centre. A very small fraction of the total polymer is terminated by a reaction which does not lead to detachment of the polymer. Possible reaction mechanisms are discussed. 相似文献
79.
Mason A. Wolak Robert C. Finn Randy S. Rarig Craig J. Thomas Robert P. Hammond Robert R. Birge Jon Zubieta Watson J. Lees 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(7):o389-o393
Fluorinated indolylfulgides are a class of photochromic organic compounds that meet many of the requirements for use as optical memory media and optical switches. The X‐ray crystal structures of a series of five photochromic fluorinated indolylfulgides have been determined, namely (3Z)‐3‐[1‐(1,2‐dimethyl‐1H‐indol‐3‐yl)‐2,2,2‐trifluoroethylidene]‐4‐(1‐methylethylidene)dihydrofuran‐2,5‐dione (trifluoromethylisopropylideneindolylfulgide), C19H16F3NO3, (I), (3Z)‐3‐[1‐(1,2‐dimethyl‐1H‐indol‐3‐yl)‐2,2,3,3,3‐pentafluoropropylidene]‐4‐(1‐methylethylidene)dihydrofuran‐2,5‐dione (pentafluoroethylisopropylideneindolylfulgide), C20H16F5NO3, (II), (3Z)‐3‐[1‐(1,2‐dimethyl‐1H‐indol‐3‐yl)‐2,2,3,3,4,4,4‐heptafluorobutylidene]‐4‐(1‐methylethylidene)dihydrofuran‐2,5‐dione (heptafluoropropylisopropylideneindolylfulgide), C21H16F7NO3, (III), (3Z)‐3‐[1‐(1,2‐dimethyl‐1H‐indol‐3‐yl)‐2,2,2‐trifluoroethylidene]‐4‐(tricyclo[3.3.1.13,7]decylidene)dihydrofuran‐2,5‐dione (trifluoromethyladamantylideneindolylfulgide), C26H24F3NO3, (IV), and (3Z)‐3‐[1‐(1,2‐dimethyl‐1H‐indol‐3‐yl)‐2,2,3,3,4,4,4‐heptafluorobutylidene]‐4‐(tricyclo[3.3.1.13,7]decylidene)dihydrofuran‐2,5‐dione (heptafluoropropyladamantylideneindolylfulgide), C28H24F7NO3, (V). The photochromic property of fulgides is based on the photochemically allowed electrocyclic ring closure of a hexatriene system to form a cyclohexadiene. For each fulgide examined, the bond lengths within the hexatriene system alternate between short and long, as expected. Comparing the structures of the five fulgides with each other demonstrates no significant difference in bond lengths, bond angles or dihedral angles within the hexatriene systems. The distance between the bond‐forming C atoms at each end of the hexatriene system does vary. Correlations of structural properties with optical properties are addressed. 相似文献
80.
Shaoxuan Ren Dr. Zishuai Zhang Eric W. Lees Arthur G. Fink Dr. Luke Melo Dr. Camden Hunt David J. Dvorak Wen Yu Wu Dr. Edward R. Grant Dr. Curtis P. Berlinguette 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(25):e202200340
Electrochemical reactors that electrolytically convert CO2 into higher-value chemicals and fuels often pass a concentrated hydroxide electrolyte across the cathode. This strongly alkaline medium converts the majority of CO2 into unreactive HCO3− and CO32− byproducts rather than into CO2 reduction reaction (CO2RR) products. The electrolysis of CO (instead of CO2) does not suffer from this undesirable reaction chemistry because CO does not react with OH−. Moreover, CO can be more readily reduced into products containing two or more carbon atoms (i. e., C2+ products) compared to CO2. We demonstrate here that an electrocatalyst layer derived from copper phthalocyanine ( CuPc ) mediates this conversion effectively in a flow cell. This catalyst achieved a 25 % higher selectivity for acetate formation at 200 mA/cm2 than a known state-of-art oxide-derived Cu catalyst tested in the same flow cell. A gas diffusion electrode coated with CuPc electrolyzed CO into C2+ products at high rates of product formation (i. e., current densities ≥200 mA/cm2), and at high faradaic efficiencies for C2+ production (FEC2+; >70 % at 200 mA/cm2). While operando Raman spectroscopy did not reveal evidence of structural changes to the copper molecular complex, X-ray photoelectron spectroscopy suggests that the catalyst undergoes conversion to a metallic copper species during catalysis. Notwithstanding, the ligand environment about the metal still impacts catalysis, which we demonstrated through the study of a homologous CuPc bearing ethoxy substituents. These findings reveal new strategies for using metal complexes for the formation of carbon-neutral chemicals and fuels at industrially relevant conditions. 相似文献