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561.
Qin G Santos C Zhang W Li Y Kumar A Erasquin UJ Liu K Muradov P Trautner BW Cai C 《Journal of the American Chemical Society》2010,132(46):16432-16441
Biofunctionalization of silicon substrates is important to the development of silicon-based biosensors and devices. Compared to conventional organosiloxane films on silicon oxide intermediate layers, organic monolayers directly bound to the nonoxidized silicon substrates via Si-C bonds enhance the sensitivity of detection and the stability against hydrolytic cleavage. Such monolayers presenting a high density of terminal alkynyl groups for bioconjugation via copper-catalyzed azide-alkyne 1,3-dipolar cycloaddition (CuAAC, a "click" reaction) were reported. However, yields of the CuAAC reactions on these monolayer platforms were low. Also, the nonspecific adsorption of proteins on the resultant surfaces remained a major obstacle for many potential biological applications. Herein, we report a new type of "clickable" monolayers grown by selective, photoactivated surface hydrosilylation of α,ω-alkenynes, where the alkynyl terminal is protected with a trimethylgermanyl (TMG) group, on hydrogen-terminated silicon substrates. The TMG groups on the film are readily removed in aqueous solutions in the presence of Cu(I). Significantly, the degermanylation and the subsequent CuAAC reaction with various azides could be combined into a single step in good yields. Thus, oligo(ethylene glycol) (OEG) with an azido tag was attached to the TMG-alkyne surfaces, leading to OEG-terminated surfaces that reduced the nonspecific adsorption of protein (fibrinogen) by >98%. The CuAAC reaction could be performed in microarray format to generate arrays of mannose and biotin with varied densities on the protein-resistant OEG background. We also demonstrated that the monolayer platform could be functionalized with mannose for highly specific capturing of living targets (Escherichia coli expressing fimbriae) onto the silicon substrates. 相似文献
562.
Gemma Packer Julien Malassis Neil Wells Mark Light Bruno Linclau 《Tetrahedron: Asymmetry》2017,28(4):539-544
A three-step synthesis of enantiomerically enriched 1,1,1-trifluoro-2-propanamine based on the use of a chiral sulfinamide auxiliary is described. The reduction of the geometrically pure Z-sulfinimine (NOE, HOE) with NaBH4 or l-Selectride leads to the corresponding (R)- or (S)-configured amine derivatives (X-ray crystallographic analysis) with 92–96% de. The typical models to explain the stereoselection for these reducing agents fail to rationalize the obtained stereoselectivities, and an in situ imine isomerization is proposed to occur. The direct use of the hydrochloric acid salt (with excess Et3N) of this poorly nucleophilic amine for epoxide opening reactions is not possible due to the higher nucleophilicity of chloride. Hence, a novel triflate salt is introduced, synthesized through ready sulfinamide hydrolysis with trimethylsilyl triflate, which can be used directly, without the need of isolating the pure amine beforehand. 相似文献
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564.
Jon-Paul R. Wells Glynn D. Jones Michael F. Reid Marina N. Popova Elena P. Chukalina 《Molecular physics》2013,111(11-12):1367-1376
Hyperfine structure is observed on several infrared transitions to the 5I7 and 5I6 multiplets of the Ho3+ C4v centre in CaF2. Particularly complex and detailed hyperfine structures are observed for transitions to the Y3 level of the 5I7 multiplet, which include the appearance of ΔIz ≠ 0 transitions. The hyperfine lines of this level are satisfactorily accounted for by strong mixing of close-lying levels of this multiplet by the perpendicular hyperfine interaction, which leads to relaxation of the ΔIz = 0 selection rule and a redistribution of the hyperfine intensities over many transitions. An excellent correspondence is found between the measured and simulated spectra. 相似文献
565.
A. Johnstone E. Pieszczek F. W. Schmidt G. Denigès J. S. C. Wells H. O. Hofman E. H. Miller H. W. Rennie W. H. Derrick Thomas Moore H. N. Warren Mengin C. A. Lobry de Bruyn Carnahan F. Emich A. Classen und R. Ludwig 《Fresenius' Journal of Analytical Chemistry》1899,38(5):307-323
Ohne Zusammenfassung 相似文献
566.
Anu Dudhia Paul E. MorrisRobert J. Wells 《Journal of Quantitative Spectroscopy & Radiative Transfer》2002,74(6):745-756
Satellite observations of atmospheric infrared spectra can be modeled accurately with line-by-line calculations, but these are too slow to be incorporated into operational retrieval schemes. However, a monochromatic calculation is still feasible if the line-by-line summation is replaced by pre-tabulated absorption coefficients, requiring a three-way optimization of storage space, accuracy and access time.Such a scheme is used for the operational processing of data from MIPAS, a limb-viewing interferometer. The tabulated data are compressed to a manageable size using singular value decomposition, although the reconstruction adds a small overhead. The number of monochromatic radiative transfer calculations is reduced by determining suitable quadrature points in the spectral domain, which reduces both processing time and data storage requirements. An important aspect of such optimizations is the control of the associated errors in the forward model calculation.The result is an acceleration of monochromatic forward model calculations by one or two orders of magnitude compared to a line-by-line calculation without any significant loss of accuracy, while obtaining data compression factors of 100 or more compared to a direct tabulation of absorption coefficients. 相似文献
567.
W. R. Bennett R. C. Wells R. E. Stevens O. Hahn Moore Kithil 《Analytical and bioanalytical chemistry》1936,105(9-10):373-378
568.
A. De Roeck J. Ellis C. Grojean S. Heinemeyer K. Jakobs G. Weiglein J. Wells G. Azuelos S. Dawson B. Gripaios T. Han J. Hewett M. Lancaster C. Mariotti F. Moortgat G. Moortgat-Pick G. Polesello S. Riemann M. Schumacher K. Assamagan P. Bechtle M. Carena G. Chachamis K. F. Chen S. De Curtis K. Desch M. Dittmar H. Dreiner M. Dührssen B. Foster M. T. Frandsen A. Giammanco R. Godbole S. Gopalakrishna P. Govoni J. Gunion W. Hollik W. S. Hou G. Isidori A. Juste J. Kalinowski A. Korytov E. Kou S. Kraml M. Krawczyk A. Martin D. Milstead V. Morton-Thurtle K. Moenig B. Mele E. Ozcan M. Pieri T. Plehn L. Reina E. Richter-Was T. Rizzo K. Rolbiecki F. Sannino M. Schram J. Smillie S. Sultansoy J. Tattersall P. Uwer B. Webber P. Wienemann 《The European Physical Journal C - Particles and Fields》2010,66(3-4):525-583
Discoveries at the LHC will soon set the physics agenda for future colliders. This report of a CERN Theory Institute includes the summaries of Working Groups that reviewed the physics goals and prospects of LHC running with 10 to 300 fb?1 of integrated luminosity, of the proposed sLHC luminosity upgrade, of the ILC, of CLIC, of the LHeC and of a muon collider. The four Working Groups considered possible scenarios for the first 10 fb?1 of data at the LHC in which (i) a state with properties that are compatible with a Higgs boson is discovered, (ii) no such state is discovered either because the Higgs properties are such that it is difficult to detect or because no Higgs boson exists, (iii) a missing-energy signal beyond the Standard Model is discovered as in some supersymmetric models, and (iv) some other exotic signature of new physics is discovered. In the contexts of these scenarios, the Working Groups reviewed the capabilities of the future colliders to study in more detail whatever new physics may be discovered by the LHC. Their reports provide the particle physics community with some tools for reviewing the scientific priorities for future colliders after the LHC produces its first harvest of new physics from multi-TeV collisions. 相似文献
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