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311.
Collaborative testing of eddy structure identification methods in free turbulent shear flows 总被引:1,自引:0,他引:1
J. P. Bonnet J. Delville M. N. Glauser R. A. Antonia D. K. Bisset D. R. Cole H. E. Fiedler J. H. Garem D. Hilberg J. Jeong N. K. R. Kevlahan L. S. Ukeiley E. Vincendeau 《Experiments in fluids》1998,25(3):197-225
The thrust of this paper is to validate, test and compare several Coherent Structure eduction methods utilizing the same
data base. The flow chosen was that of an experimental study of a plane, incompressible, fully developed turbulent two-stream
mixing layer. The mixing layer was chosen as the data base because it has been studied extensively from a coherent structures
point of view. In addition, its characteristics (similarity, convection velocities, etc.) are well documented. There are also
no wall effects so that comparisons between techniques are simplified. The data was collected from hot wire rakes with good
spatial resolution thus allowing the contributors to apply and test different structure eduction techniques. The techniques
chosen for discussion and used here have found wide utilization over the past decade, and all hold forth the promise of extensive
application in the future. These include: Conditional Sampling (Vorticity-based and other methods); Wavelets; Pattern Recognition
Analysis; Proper Orthogonal Decomposition; Stochastic Estimation; Topological Concept-based methods; Full Field Methods (e.g.,
pseudo flow visualization). All are illustrated by application to the mixing layer data base, and comparisons made between
the results. This common study has shown that direct comparisons between results of several methods are now possible. Good
quantitive and qualitative agreement between the different methods have been observed as well as some differences noted. As
an example, the size of the averaged structures computed from the various methods compare to within 6 percent.
Received: 15 December 1994/Accepted: 18 December 1997 相似文献
312.
The crystallization kinetics of syndiotactic polypropylene (sPP)/high-density polyethylene (HDPE) blends were investigated
by thermal and microscopical methods. Isothermal crystallization obtained by differential scanning calorimetry (DSC) was used
to study the nucleation ability of HDPE on sPP crystallization. Morphological studies with polarized light microscopy (PLM)
of solution cast films resulted in a transcrystalline-like overgrowth of the sPP on HDPE spherulites. The arrangement of the
HDPE lamellar crystals in the blend were observed in transmission electron microscopy (TEM). But from these results, no straightforward
conclusion about the transcrystalline nature of the sPP crystals can be given.
Received: 24 November 1997 Accepted: 23 February 1998 相似文献
313.
In order to complement a previous collaborative testing of eddy structure identification methods in free turbulent shear
flows, a study about the influence of the transverse location of these large-scale vortical structures on their signatures
for the same referenced data base is carried out. Using vorticity-based conditional sampling, events which are located on
the same transverse locations are selected and averaged. Results show that a coherent structure has its proper identity contained
in its core and keeps it whatever its trajectory. In this way, only its signature in comparison with the surrounding environment
changes. The comparison with vorticity-based conditional sampling without this transverse selection brings to the fore a bias
on the signature of coherent structures. This result throws back into question previous conclusions about the morphology of
structures and related energy transfer scenarios.
Received: 24 July 2000 / Accepted: 25 June 2001 Published online: 29 November 2001 相似文献
314.
L. Bonnet J. C. Rayez 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,38(1):65-73
In the mid-seventies, Case and Herschbach argued that
for
complex-forming three-atom reactions governed by long-range forces and
performed in supersonic molecular beam experiments, vectorial properties
are determined by a single parameter Λ' = 〈L'/(L' + j')〉, L' and j' being
respectively the moduli of the orbital and rotational angular momenta of the
products. A simple mathematical relation between vectorial properties and
Λ' was then proposed. However, Λ' must be determined
beforehand by
phase space theory calculations. Besides, we have recently shown that scalar
properties are mainly controled by two factors ρ'1 and ρ'2
respectively
called angular excitation and diatomic inertial contribution. We show here
that these factors control also vectorial properties. Moreover, the way they
control them is summarized in a set of four figures. The advantage of our
method is that ρ'1 and ρ'2 are related to the mechanical
parameters of the
reaction by very simple formulas, contrary to Λ'. Last by not
least, our
parameters appear to be mostly independent, so that vectorial properties
cannot be said to strictly depend on Λ'. Nevertheless, it turns out
that the
rule proposed by Case and Herschbach is reasonable in many realistic
situations. 相似文献
315.
Let (P,≤) be a partially ordered set. The poset Boolean algebra of P, denoted F(P), is defined as follows: The set of generators of F(P) is {x
p
: p∈P}, and the set of relations is {x
p
⋅x
q
=x
p
: p≤q}. We say that a Boolean algebra B is well-generated, if B has a sublattice G such that G generates B and (G,≤
B
|G) is well-founded. A well-generated algebra is superatomic.
THEOREM 1. Let (P,≤) be a partially ordered set. The following are equivalent. (i) P does not contain an infinite set of pairwise incomparable elements, and P does not contain a subset isomorphic to the chain of rational numbers, (ii) F(P) is superatomic, (iii) F(P) is well-generated.
The equivalence (i) ⇔ (ii) is due to M. Pouzet. A partially ordered set W is well-ordered, if W does not contain a strictly decreasing infinite sequence, and W does not contain an infinite set of pairwise incomparable elements.
THEOREM 2. Let F(P) be a superatomic poset algebra. Then there are a well-ordered set W and a subalgebra B of F(W), such that F(P) is a homomorphic image of B.
This is similar but weaker than the fact that every interval algebra of a scattered chain is embeddable in an ordinal algebra.
Remember that an interval algebra is a special case of a poset algebra.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
316.
Bonnet D Riché S Loison S Dagher R Frantz MC Boudier L Rahmeh R Mouillac B Haiech J Hibert M 《Chemistry (Weinheim an der Bergstrasse, Germany)》2008,14(20):6247-6254
Two novel solid-phase organic tagging (SPOrT) resins were synthesized to facilitate the labeling of peptides and small organic compounds with a fluorescent probe. Both resins were obtained from the commercially available backbone amide linker (BAL) resin. Following the solid-phase synthesis of model compounds, a tripeptide and benzazepine, the fluorescent probe derived from Lissamine Rhodamine B was incorporated through CuI-catalyzed 1,3-dipolar cycloaddition. Final cleavage in acidic media enabled access to both types of molecules in good yield with high purity. The SPOrT resin was successfully applied to the preparation of the first non-peptidic fluorescent compound with a nanomolar affinity for the human vasopressin V2 receptor (V2R) subtype. This molecule will find application in binding assays that use polarization or fluorescence resonance energy-transfer (FRET) techniques. The SPOrT resins are also well suited for other tags and the parallel synthesis of a fluorescently tagged library for protein screening. 相似文献
317.
Fuyi Zhang Bruno Bernet Véronique Bonnet Olivier Dangles Francisco Sarabia Andrea Vasella 《Helvetica chimica acta》2008,91(4):608-617
Chitosan ( 1 ) was prepared by basic hydrolysis of chitin of an average molecular weight of 70000 Da, 1H‐NMR spectra indicating almost complete deacetylation. N‐Phthaloylation of 1 yielded the known N‐phthaloylchitosan ( 2 ), which was tritylated to provide 3a and methoxytritylated to 3b . Dephthaloylation of 3a with NH2NH2?H2O gave the 6‐O‐tritylated chitosan 4a . Similarly, 3b gave the 6‐O‐methoxytritylated 4b . CuSO4‐Catalyzed diazo transfer to 4a yielded 95% of the azide 5a , and uncatalyzed diazo transfer to 4b gave 82% of azide 5b . Further treatment of 5a with CuSO4 produced 2‐azido‐2‐deoxycellulose ( 7 ). Demethoxytritylation of 5b in HCOOH gave 2‐azido‐2‐deoxy‐3,6‐di‐O‐formylcellulose ( 6 ), which was deformylated to 7 . The 1,3‐dipolar cycloaddition of 7 to a range of phenyl‐, (phenyl)alkyl‐, and alkyl‐monosubstituted alkynes in DMSO in the presence of CuI gave the 1,2,3‐triazoles 8 – 15 in high yields. 相似文献
318.
319.
Bonnet S Siegler MA Costa JS Molnár G Bousseksou A Spek AL Gamez P Reedijk J 《Chemical communications (Cambridge, England)》2008,(43):5619-5621
The two-step spin crossover of a new mononuclear iron(ii) complex is studied by magnetic, crystallographic and calorimetric methods revealing two successive first-order phase transitions and an ordered intermediate phase built by the repetition of the unprecedented [HS-LS-LS] motif. 相似文献
320.