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31.
Ruzzarin Anelise Lima da Cruz Paulo Alberto de Almeida Rangel Johnny da Silva Carlos José Iwahara Akira Lopes Ricardo Tadeu 《Journal of Radioanalytical and Nuclear Chemistry》2020,323(2):721-729
Journal of Radioanalytical and Nuclear Chemistry - A procedure for characterizing the activity amount of 125I seed was developed in order to establish a secondary standard activity measurement... 相似文献
32.
Inequalities based on a generalization of concavity 总被引:4,自引:0,他引:4
Paul W. Eloe Johnny Henderson 《Proceedings of the American Mathematical Society》1997,125(7):2103-2107
The concept of concavity is generalized to functions, , satisfying order differential inequalities, , and homogeneous two-point boundary conditions, , for some . A piecewise polynomial, which bounds the function, , below, is constructed, and then is employed to obtain that , where max and denotes the supremum norm. An analogous inequality for a related Green's function is also obtained. These inequalities are useful in applications of certain cone theoretic fixed point theorems.
33.
Panuwet P Nguyen JV Kuklenyik P Udunka SO Needham LL Barr DB 《Analytical and bioanalytical chemistry》2008,391(5):1931-1939
We have developed a method using on-line solid-phase extraction–high-performance liquid chromatography–tandem mass spectrometry
(SPE-HPLC-MS/MS) and isotope dilution quantification to measure atrazine and seven atrazine metabolites in urine. The metabolites
measured were hydroxyatrazine, diaminochloroatrazine, desisopropylatrazine, desethylatrazine, desethylatrazine mercapturate,
atrazine mercaturate and atrazine itself. Our method has good precision (relative standard deviations ranging from 4 to 20%
at 5, 10 and 50 ng/mL), extraction efficiencies of 67 to 102% at 5 and 25 ng/mL, relative recoveries of 87 to 112% at 5, 25,
50 and 100 ng/mL limits of detection (LOD) ranging from 0.03 to 2.80 ng/mL. The linear range of our method spans from the
analyte LOD to 100 ng/mL (40 ng/mL for atrazine and atrazine mercapturate) with R
2 values of greater than 0.999 and errors about the slope of less than 3%. Our method is rapid, cost-effective and suitable
for large-scale sample analyses and is easily adaptable to other biological matrices. More importantly, this method will allow
us to better assess human exposure to atrazine-related chemicals.
Figure A schematic representation showing the elution of the analytes from the solid-phase extraction cartridge onto the analytical
column for chromatographic separation prior to MS/MS analysis 相似文献
34.
Ying Yu Cheng Lei Minghua Chen Hongwei Chen Sigang Yang Shizhong Xie 《中国光学快报(英文版)》2014,12(10):100601-4
By optimizing the gain configuration and length of the loop, a 90-tone optical frequency comb (OFC) is successfully generated based on recirculating frequency shifter structure. The peak-to-peak power fluctuation of the 90-tone OFC is 4.26 dB and the tone-to-noise ratio is higher than 19.17 dB. To further analyze the noise accumulation feature of the tones when travelling around the loop, linewidth of the tones is measured by delayed self-heterodyne interferometer structure. The result shows the linewidth of the tones deteriorates little during the recirculating process, indicating that the generated OFC is an ideal multi-wavelength source for high-speed communication svstems. 相似文献
35.
We develop a compact and high-energy Nd:YAG slab laser system consisting of an oscillator and an amplifier for space applications. The oscillator is a diode-side-pumped electro-optically Q-switched slab laser with a cross-Porro resonator. The KD*P Pockels cell with a low driving voltage of 950 V is used to polarization output coupling. The amplifier is a Nd:YAG zigzag slab pumped at bounces. The maximum output pulse energy of 341 m3 with 13 ns pulse duration is obtained from the system at the repetition rate of 20 Hz and the beam quality factors are M2=3.1 and M2=3.5. The beam pointing stabilities of the laser system are 3.05μrad in the X-direction and 3.99 grad in the Y-direction, respectively. 相似文献
36.
A protocol to generate parameters for the AMOEBA polarizable force field for small organic molecules has been established,
and polarizable atomic typing utility, Poltype, which fully automates this process, has been implemented. For validation,
we have compared with quantum mechanical calculations of molecular dipole moments, optimized geometry, electrostatic potential,
and conformational energy for a variety of neutral and charged organic molecules, as well as dimer interaction energies of
a set of amino acid side chain model compounds. Furthermore, parameters obtained in gas phase are substantiated in liquid-phase
simulations. The hydration free energy (HFE) of neutral and charged molecules have been calculated and compared with experimental
values. The RMS error for the HFE of neutral molecules is less than 1 kcal/mol. Meanwhile, the relative error in the predicted
HFE of salts (cations and anions) is less than 3% with a correlation coefficient of 0.95. Overall, the performance of Poltype
is satisfactory and provides a convenient utility for applications such as drug discovery. Further improvement can be achieved
by the systematic study of various organic compounds, particularly ionic molecules, and refinement and expansion of the parameter
database. 相似文献
37.
Aude Marjolin Christophe Gourlaouen Carine Clavaguéra Pengyu Y. Ren Johnny C. Wu Nohad Gresh Jean-Pierre Dognon Jean-Philip Piquemal 《Theoretical chemistry accounts》2012,131(4):1198
In this contribution, we focused on the use of polarizable force fields to model the structural, energetic, and thermodynamical
properties of lanthanides and actinides in water. In a first part, we chose the particular case of the Th(IV) cation to demonstrate
the capabilities of the AMOEBA polarizable force field to reproduce both reference ab initio gas-phase energetics and experimental
data including coordination numbers and radial distribution functions. Using such model, we predicted the first polarizable
force field estimate of Th(IV) solvation free energy, which accounts for −1,638 kcal/mol. In addition, we proposed in a second
part of this work a full extension of the SIBFA (Sum of Interaction Between Fragments Ab initio computed) polarizable potential
to lanthanides (La(III) and Lu(III)) and to actinides (Th(IV)) in water. We demonstrate its capabilities to reproduce all
ab initio contributions as extracted from energy decomposition analysis computations, including many-body charge transfer
and discussed its applicability to extended molecular dynamics and its parametrization on high-level post-Hartree–Fock data. 相似文献
38.
Rafael Hernández García Moni Behar Johnny Ferraz Dias Margarita Edelia Villanueva Tagle María Dolores Durruthy Rodríguez Francisco de Paula Calderón Piñar Mario Simeón Pomares Alfonso 《X射线光谱测定》2012,41(3):156-163
A particle‐induced X‐ray emission (PIXE) technique has been used in the determination of the principal components Pb, Zr and Ti and the substituting elements Sr, Cr, Nb and La in lead zirconate titanate ceramics. In general, precision of analysis was concentration dependent from each element under study. For Pb, precision varied between 0.13% and 0.16%, at higher concentration of 59.32–64.5%. It was around 6–9% for Sr, Cr and Nb at concentrations of 1% or lower. Particular attention was devoted to the estimation of the analysis trueness. With this purpose, three methods were applied: (1) comparison of PIXE and inductively coupled plasma optical emission spectrometry concentrations, (2) recovery study and (3) comparison with a laboratory standard. Trueness of analysis was around 100 ± 10% for the evaluated elements Pb, Zr, Ti, Sr and Cr. The expected stoichiometry and elemental composition homogeneity of a wide group of produced ceramics were confirmed by the PIXE technique. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
39.
M. Lazar H. Vang P. Brosselard C. Raynaud P. Cremillieu J.-L. Leclercq A. Descamps S. Scharnholz D. Planson 《Superlattices and Microstructures》2006,40(4-6):388
SiC is currently an important topic in power devices. This new technology leads to lower power losses, faster switching, and higher working temperature. The design of SiC power devices requires the integration of edge termination techniques to obtain a high blocking voltage. The mesa structure approach is one well-established method. It could be used alone or in combination with a Junction Termination Extension (JTE). The mesa consists of a structure that removes material around the pn-junction. Due to the strong Si–C bonds, conventional chemical–wet etching solutions are inefficient on SiC, so plasma methods are required to etch SiC.The presented work is based on the use of an RIE reactor with an SF6/ O2 plasma. Its geometry structure and parameters were optimized. An etch rate of 0.35 μm/min was obtained without any trenching phenomenon. Trenches deeper than 10 μm deep were realized with a nickel etching mask that shows a high selectivity. AFM analysis revealed an etched surface as smooth as the initial one. 相似文献
40.
This research investigates the problem of scheduling jobs on a set of parallel machines where the speed of the machines depends on the allocation of a secondary resource. The secondary resource is fixed in quantity and is to be allocated to the machines at the start of the schedule. The scheduling objective is to minimize the number of tardy jobs. Two versions of the problem are analyzed. The first version assumes that the jobs are pre-assigned to the machines, while the second one takes into consideration the task of assigning jobs to the machines. The paper proposes an Integer Programming formulation to solve the first case and a set of heuristics for the second. 相似文献