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991.
Data on multiplicity distributions inp
collisions at 0.3, 0.546, 1.0 and 1.8 GeV CM energy from recent experiments at FNAL and its relation to previous experiments are analyzed. Fits to the data and a critical discussion of the results are presented.Partially supported by CONICET 相似文献
992.
Brick DH Widgoff M Beilliere P Lutz P Narjoux JL Gelfand N Alyea ED Bloomer M Bober J Busza W Cole B Frank TA Fuess TA Grodzins L Hafen ES Haridas P Huang D Huang HZ Hulsizer R Kistiakowsky V Ledoux RJ Milstene C Noguchi S Oh SH Pless IA Steadman S Stoughton TB Suchorebrow V Tether S Trepagnier PC Wadsworth BF Wu Y Yamamoto RK Cohn HO Calligarich E Corti G Dolfini R Gianini G Introzzi G Ratti S Badiak M DiMarco R Jacques PF Kalelkar M Plano RJ Stamer PE Brucker EB Koller EL Alexander G 《Physical review D: Particles and fields》1992,45(3):734-742
993.
994.
995.
Oh HB Lin C Hwang HY Zhai H Breuker K Zabrouskov V Carpenter BK McLafferty FW 《Journal of the American Chemical Society》2005,127(11):4076-4083
Previous gas-phase methods for infrared photodissociation spectroscopy (IRPD) require sample volatility. Our method instead uses electrospray ionization to introduce even large nonvolatile molecules into a Fourier transform mass spectrometer, where extended (>15 s) ion storage makes possible high sensitivity spectral measurements with an OPO laser over a range of 3050-3800 cm(-1). The spectra of 22 gaseous proton-bound amino acid complexes are generally correlated with the H-stretching frequencies established for O-H and N-H functional groups in solution. For theoretical structure predictions of the Gly2H+ and N-acylated Asp2H+ dimers, IRPD spectra clearly differentiate between the predicted lowest energy conformers. In contrast to solution, in the gas phase the glycine zwitterion is approximately 20 kcal/mol less stable than the neutral; however, glycine is clearly zwitterionic in the gaseous GlyLysH+ dimer. The level of theory is inadequate for the larger Lys2H+ dimer, as all low energy predicted structures have free carboxyl O-H groups, in contrast to the IR spectrum. IRPD appears to be a promising new technique for providing unique information on a broad range of biomolecular and other gaseous ions, especially on noncovalent bonding involving O-H and N-H groups. 相似文献
996.
Bandyopadhyay I Lee HM Tarakeshwar P Cui C Oh KS Chin J Kim KS 《The Journal of organic chemistry》2003,68(17):6571-6575
The highly stereospecific and regiospecific recognition of alpha-amino acids exhibited by a novel Co(III) metal complex embodied in the experimental work (Nature 1999, 401, 254) is rationalized from the energetics and structural characteristics with the use of density functional calculations. The steric repulsion between the chiral center of the receptor [Co(III) complex] and alanine has been a cause for the discrimination of complex stabilities. The energies evaluated for all possible alanine binding modes clearly reveal regiospecificity. Our main emphasis is laid on the base-catalyzed epimerization reaction that drives the stereospecific recognition to near completion. The conducted tour mechanism is found to be the most likely candidate. A similar role by the equivalent Zn(II) complex is found. 相似文献
997.
The aminolysis of aryl N-ethyl thiocarbamates (EtNHC(=O)SC(6)H(4)Z) with benzylamines (XC(6)H(4)CN(2)NH(2)) in acetonitrile at 30.0 degrees C is investigated. The rates are faster than the corresponding values for aryl N-phenyl thiocarbamates (PhNHC(=O)SC(6)H(4)Z), reflecting a stronger push to expel the leaving group by EtNH than the PhNH nonleaving group in a concerted process. The negative rho(XZ) (-0.86) and failure of the reactivity-selectivity principle found are consistent with the concerted mechanism. The kinetic isotope effects involving deuterated nucleophiles (k(H)/k(D) = 1.5-1.7) and low Delta H(++) with large negative Delta S(++) values suggest a hydrogen bond cyclic transition state. 相似文献
998.
Z‐Hun Kim Hwa Yeon Oh Younghoon Choi Hanwool Park Daewoo Jung Jong‐Min Kim Yang Ho Na Sang‐Min Lim Choul‐Gyun Lee Jin‐Kyun Lee 《Journal of polymer science. Part A, Polymer chemistry》2016,54(1):108-114
In this article, we demonstrate that hydrogel‐based composite membranes are used as semipermeable materials for the construction of photobioreactors (PBRs). PBRs are developed to culture microalgae using nutrients dissolved in seawater, and thus they need to be fabricated with membranes possessing sufficient material‐transport properties. While hydrogels are characterized by their highly swelling nature in water and therefore have desirable transport of dissolved matter, they lack the mechanical strength to be cast into thin structures of large surface area. This issue motivated us to design a new concept, i.e., fabric‐hydrogel composite membranes ( FHCM s). A cotton fabric inside the hydrogel matrix endows the composite with tensile strength, which enables casting of FHCM s into thin membranes. Several FHCM s were prepared with 2‐hydroxyethyl methacrylate ( HEMA ), cross‐linking poly(ethylene glycol) dimethacrylate ( PEGDMA ) and a sheet of gauze by controlling the composition of the monomers and water. In the permeability measurement of nitrate ions, a key ingredient for the growth of microalgae, the permeability coefficient reached as high as 1.2 x 10?8 m2 min?1, which is roughly three times higher than that of a commercially available semipermeable membrane (3.3 x 10?9 m2 min?1). In the following evaluation of microalgal culture, a PBR constructed with a FHCM was able to maintain sufficient ion concentration and pH of the culture broth, supporting microalgal growth. These results suggest that the composite membranes with hydrogel and fabric have potential in the application of microalgal culture for bio‐diesel production in a marine environment. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 108–114 相似文献
999.
Band alignment and defect states in amorphous GaInZnO thin films grown on SiO2/Si substrates 下载免费PDF全文
Sung Heo JaeGwan Chung Jae Cheol Lee Taewon Song Seong Heon Kim Dong‐Jin Yun Hyung Ik Lee KiHong Kim Gyeong Su Park Jong Soo Oh Dong Wook Kwak DongWha Lee Hoon Young Cho Dahlang Tahi Hee Jae Kang Byoung‐Deog Choi 《Surface and interface analysis : SIA》2016,48(10):1062-1065
The band alignment and defect states of GaInZnO thin films grown on SiO2/Si via radio frequency (RF) magnetron sputtering were investigated by using X‐ray photoelectron spectroscopy, reflection electron energy loss spectroscopy, thermally stimulated exo‐electron emission and photo‐induced current transient spectroscopy.The band gap via reflection electron energy loss spectroscopy was 3.2 eV. The defect states via photo‐induced current transient spectroscopy and thermally stimulated exo‐electron emission were at 0.24, 0.53, 1.69 and 2.01 eV below the conduction band minimum of GIZO thin films, respectively. The defect states at 0.24 and 0.53 eV are related to the field‐effect mobility, and the defect stated at 1.69 and 2.01 eV is related to the oxygen vacancy defect. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
1000.
Hyo-Young Mun Hong-Gyu Park Hae-Chang Jeong Ju Hwan Lee Byeong-Yun Oh 《Liquid crystals》2017,44(3):538-543
Doping with cerium (IV) oxide (CeO2) nanoparticles can significantly enhance the thermal stability and electro-optical (EO) properties of nematic liquid crystal (NLC) systems. Thermal stability was improved without aggregation and reduction of transmittance by adding CeO2 nanoparticles in a liquid crystal medium. In particular, the EO properties greatly improved in CeO2-dispersed NLC cells. The threshold voltage reduced from 3.027 to 2.279 V and the response time decreased from 13.097 to 9.970 ms with increased CeO2 nanoparticles in the NLC cells. The improved properties of liquid crystals doped with CeO2 nanoparticles depend on the anchoring energy and the electric field of the CeO2-dispersed liquid crystal displays. 相似文献