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201.
James D. Korp Ivan Bernal L. Avens Jerry L. Mills 《Journal of chemical crystallography》1983,13(4):263-272
The X-ray crystal structure of 3-ammonium-4-hydroxyphenylarsonic acid chloride dihydrate has been determined from single-crystal diffraction data. The compound crystallizes in the orthorhombic space groupPna 21 with four molecules in a unit cell of dimensionsa=17.712(7),b=13.468(4), andc=4.798(2) Å. The structure was solved by the Patterson method and refined to a finalR value of 2.1%. The average C-C phenyl distance is 1.393 Å, but two bonds are somewhat shorter than the others. This, coupled with the fact that the C-O and C-As bonds are shorter than normal, makes it appear as if there is a minor resonance contributor of a keto form. The C-N bond length of 1.443 Å is intermediate between values found in aminophenols and other ammoniumphenols. The H2AsO3 group is nearly tetrahedral, with the double-bonded oxygen rotated 9° out of the phenyl plane about the C-As bond. There is an extensive hydrogen-bonding system, involving every one of the OH and NH hydrogens, through the chloride and the waters of crystallization. 相似文献
202.
H.N. Mills 《Journal of Non》1982,47(1):27-46
Those optical properties of glass of most interest in the soda-lime-silica container composition field are refractive index, reflection, transmittance and absorption. These properties relate to measurement of internal stress, light protection, heat transmission and visual color. Spectrophotometric measurement of transmission/absorbance properties and use of the C.I.E. system to express color parameters are useful in color control to meet customer specifications. 相似文献
203.
In a previous work [#!ref1!#], the flow velocity of a steady two-dimensional granular flow along an inclined wall was investigated.
The scaling law for the velocity field was found in good agreement with recent experimental results. The purpose of the present
paper is to reformulate in more systematic manner and in a somewhat more general context the equations of mass and momentum
conservation for dense granular flow, and also to present some new results with particular emphasis on roughness influence
and dynamic dilatancy. Theoretical results are found in good agreement with experiments.
Received 19 July 1999 and Received in final form 14 October 1999 相似文献
204.
KM Clauwaert Van Bocxlaer JF HJ Major JA Claereboudt WE Lambert Van den Eeckhout EM Van Peteghem CH De Leenheer AP 《Rapid communications in mass spectrometry : RCM》1999,13(14):1540-1545
This paper describes the investigation of the potential of a quadrupole orthogonal acceleration time-of-flight mass spectrometer (Q-TOF) equipped with an atmospheric pressure ionisation interface for quantitative measurements of small molecules separated by reversed phase liquid chromatography. To this end, the detection limits and linear dynamic range in particular were studied in an LC/MS/MS experiment using 3,4-methylenedioxymethamphetamine standards and 3,4-methylenedioxyethylamphetamine for internal standardisation. In a second phase, the experiment was repeated with real biological extracts (whole blood, serum, and vitreous humour). A calibration for 3,4-methylenedioxymethamphetamine and its metabolite 3,4-methylenedioxyamphetamine was prepared in each of these matrices again using 3,4-methylenedioxyethylamphetamine as internal standard. The resulting quantitative data were compared with those obtained by liquid chromatography with fluorescence detection for the same extracts. The Q-TOF results revealed excellent sensitivity and a linear dynamic range of nearly four decades (2-10 000 pg on-column, r(2) = 0.9998, 1/x weighting). Furthermore, all the calibration curves prepared in biological material were superimposable, LC/MS/MS and LC-fluorescence, and the quantitative results for actual samples compared very favourably. It was concluded that the Q-TOF achieves a linear dynamic range for quantitative LC/MS/MS work exceeding that of fluorescence detection and at much better absolute sensitivity. Copyright 1999 John Wiley & Sons, Ltd. 相似文献
205.
206.
Assessing model fit by cross-validation 总被引:8,自引:0,他引:8
Hawkins DM Basak SC Mills D 《Journal of chemical information and computer sciences》2003,43(2):579-586
When QSAR models are fitted, it is important to validate any fitted model-to check that it is plausible that its predictions will carry over to fresh data not used in the model fitting exercise. There are two standard ways of doing this-using a separate hold-out test sample and the computationally much more burdensome leave-one-out cross-validation in which the entire pool of available compounds is used both to fit the model and to assess its validity. We show by theoretical argument and empiric study of a large QSAR data set that when the available sample size is small-in the dozens or scores rather than the hundreds, holding a portion of it back for testing is wasteful, and that it is much better to use cross-validation, but ensure that this is done properly. 相似文献
207.
In this paper, we show how an extended Guided Local Search (GLS) can be applied to the Quadratic Assignment Problem (QAP). GLS is a general, penalty-based meta-heuristic, which sits on top of local search algorithms, to help guide them out of local minima. We present empirical results of applying several extended versions of GLS to the QAP, and show that these extensions can improve the range of parameter settings within which Guided Local Search performs well. Finally, we compare the results of running our extended GLS with some state of the art algorithms for the QAP. 相似文献
208.
Allen P. Mills Jr. 《Applied Surface Science》2008,255(1):3-20
The purpose of this paper is to remember as many good qualities of our friend Karl Canter as I can, as an antidote to the loss of such a magnanimous, generous, inventive and amusing person. The paper endeavours to distill the essence in simple terms of some of Karl's important scientific contributions and say what I know of how these accomplishments were made possible and molded by his various character traits, illustrated with the few anecdotes that I remember. 相似文献
209.
Donald Mills 《Journal of Number Theory》2002,92(1):87-98
Let Fq denote the finite field of q elements, q=pe odd, let χ1 denote the canonical additive character of Fq where χ1(c)=e2πiTr(c)/p for all c∈Fq, and let Tr represent the trace function from Fq to Fp. We are interested in evaluating Weil sums of the form S=S(a1, …, an)=∑x∈Fq χ1(D(x)) where D(x)=∑ni=1 aixpαi+pβi, αi?βi for each i, is known as a Dembowski-Ostrom polynomial (or as a D-O polynomial). Coulter has determined the value of S when D(x)=axpα+1; in this note we show how Coulter's methods can be generalized to determine the absolute value of S for any D-O polynomial. When e is even, we give a subclass of D-O polynomials whose Weil sums are real-valued, and in certain cases we are able to resolve the sign of S. We conclude by showing how Coulter's work for the monomial case can be used to determine a lower bound on the number of Flq-solutions to the diagonal-type equation ∑li=1 xpγ+1i+(xi+λ)pγ+1=0, where l is even, e/gcd(γ, e) is odd, and h (X)=λpe−γXpe−γ+λpγX is a permutation polynomial over Fq. 相似文献
210.
Pencer J Mills T Anghel V Krueger S Epand RM Katsaras J 《The European physical journal. E, Soft matter》2005,18(4):447-458
Using coarse grained models of heterogeneous vesicles we
demonstrate the potential for small-angle neutron scattering
(SANS) to detect and distinguish between two different categories
of lateral segregation: 1) unilamellar vesicles (ULV) containing a
single domain and 2) the formation of several small domains or
“clusters” (~10 nm in radius) on a ULV. Exploiting the
unique sensitivity of neutron scattering to differences between
hydrogen and deuterium, we show that the liquid ordered (lo)
DPPC-rich phase can be selectively labeled using chain deuterated
dipalymitoyl phosphatidylcholine (dDPPC), which greatly
facilitates the use of SANS to detect membrane domains. SANS
experiments are then performed in order to detect and
characterize, on nanometer length scales, lateral heterogeneities,
or so-called “rafts”, in ~30 nm radius low polydispersity
ULV made up of ternary mixtures of phospholipids and cholesterol.
For 1:1:1 DOPC:DPPC:cholesterol (DDC) ULV we find evidence for the
formation of lateral heterogeneities on cooling below 30 °C. These heterogeneities do not appear when DOPC is
replaced by SOPC. Fits to the experimental data using coarse
grained models show that, at room temperature, DDC ULV each
exhibit approximately 30 domains with average radii of ~10 nm. 相似文献