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81.
Electric dipole radiation consists of traveling and evanescent plane waves. When radiation is detected in the far field, only the traveling waves will contribute to the intensity distribution, as the evanescent waves decay exponentially. We propose a method to spatially separate the traveling and evanescent waves before detection. It is shown that when the radiation passes through an interface, evanescent waves can be converted into traveling waves and can subsequently be observed in the far field. Let the radiation be observed under angle theta(t) with the normal. Then there exists an angle theta(ac) such that for 0 < or = theta(t) < theta(ac) all intensity originates in traveling waves, whereas for theta(ac) < theta(t) < pi/2 only evanescent waves contribute. It is shown that with this technique and under the appropriate conditions almost all far-field power can be provided by evanescent waves. 相似文献
82.
Henk M. Buck 《International journal of quantum chemistry》2011,111(15):4472-4482
We describe with molecular model studies based on the intrinsic parameters of van't Hoff's regular tetrahedron nucleophilic and electrophilic addition‐substitution reactions via a selected reaction coordinate for the displacement of carbon. Geometries of stable, intermediate transition complexes or transition states are compared with the corresponding ab initio values. Specific attention is given on the hypervalent and nonhypervalent character of carbon supported by ab initio calculations, our model consideration and experimental evidence. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2011 相似文献
83.
Jaap Noordmans Herbert Wormeester Henk J. Busscher 《Colloids and surfaces. B, Biointerfaces》1999,15(3-4):227-233
In this paper two in situ techniques are combined to simultaneously examine protein adsorption at the solid–liquid interface from sessile solution droplets. With axisymmetric drop shape analysis by profile (ADSA-P) the change in solid–liquid interfacial tension is determined, while ellipsometry is employed to measure the amount of protein adsorbed from the same solution droplet at the solid–liquid interface. Three proteins (human serum albumin (HSA), immunoglobulin G (IgG) and fibrinogen (Fb)) were dissolved to a concentration of 0.05 mg ml−1 in PBS (pH 7) and sessile droplets were placed for 2 h on a 47.8 nm thick gold coating on glass. The gold coated glass was positioned onto a quartz prism with immersion oil. The prism was aligned in a rotating analyser ellipsometer and the optical beam was thus allowed to be reflected at the hydrophobic gold surface. The ADSA-P set-up was built in 90° cross-beamed set-up around the prism. By combining the results for the adsorbed amounts and the interfacial tension changes over the two hour adsorption period, two stages in the adsorption process could be distinguished. In the first stage, the adsorbed amounts increase in correspondence with the interfacial tension changes, indicating that the interfacial tension changes are caused by adsorption, whereas in the second stage interfacial tension changes continue despite the adsorbed amounts being constant. Consequently, the second stage must be associated with conformational changes of the adsorbed proteins. For HSA and Fb, the conformational contribution to the interfacial tension changes (7.8 and 5.3 mJ m−2, respectively) were approximately 2-fold the adsorption contribution, while for IgG both were equal around 3 mJ m−2. 相似文献
84.
Martin Giera Jon S. B. de Vlieger Henk Lingeman Hubertus Irth Wilfried M. A. Niessen 《Rapid communications in mass spectrometry : RCM》2010,24(10):1439-1446
Structural elucidation of six regioisomers of mono‐N‐octyl derivatized neomycin is achieved using MSn (up to n = 4) on an ion trap time‐of‐flight (IT‐TOF) instrument equipped with electrospray ionization. The mixture of six derivatized neomycin analogues was generated by reductive amination in a shotgun synthetic approach. In parallel to the liquid chromatography/mass spectrometry (LC/MS) detection, the antibacterial activity of the neomycin regioisomers was tested by post‐column addition of buffer and bacterial inocula, subsequent microfractionation of the resulting mixture, incubation, and finally a chemiluminescence‐based bioactivity measurement based on the production of bacterial ATP. The MS‐based high‐resolution screening approach described can be applied in medicinal chemistry to help in designing and producing new antibiotic substances, which is particularly challenging due to the high functionality of most antibiotic substances, therefore requiring advanced (hyphenated) separation and detection techniques for compound mixtures. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
85.
86.
Quality management of laboratory medicine has become a hot topic at many conferences. Also, many national and international
organizations have created working groups and committees with the task of working out standards, guidelines or recommendations
for quality management of medical laboratories. We have observed that there is a great deal of interest not only from professional
and scientific organizations directly involved in medical laboratory tests, but also from accreditation and certification
bodies, from test laboratories in general, from in vitro diagnostic devices (IVD) manufacturers and their associations, and
from other medical laboratory suppliers. However, we found that all these parties were discussing from their own point of
view, without taking into account the position of other involved partners and that there was a need for creating a discussion
forum for quality management in clinical laboratories. So in 1995, we started the Antwerp conferences on quality (r)evolution
in clinical laboratories. The aim was to bring together all concerned partners and to establish a forum for brainstorming,
independently of any pressure group. The leitmotif for the Antwerp conferences (Fig. 1) is a chain model showing the interfaces
and relationships between all the partners involved in laboratory tests. During the conferences, this chain model has been
examined from different angles and a summary of the concepts evolving from the discussions can be found in the conference
abstracts and conference review reports in this journal. A Selection of ideas emerging from these conferences are presented
below.
Received: 5 October 1998 · Accepted: 20 October 1998 相似文献
87.
MartinHenk GeorgeA.Tsintsifas 《数学进展》2007,36(4):441-446
对于一个给定椭球,本文给出了它的任一全等椭球都包含一个整点的一个充分必要条件. 相似文献
88.
Henk A. Van Doren Ralph Van Der Geest Cornelis F. De Ruijter Richard M. Kellogg Hans Wynberg 《Liquid crystals》1990,8(1):109-121
A short review of the scope and limitations of liquid-crystalline behaviour in carbohydrate derivatives is presented. In order to investigate the influence of structure variations on the thermal behaviour of monosaccharide amphiphiles, six homologous series of D-glucose and 2-deoxy-D-glucose derivatives with an aminolinked n-alkyl chain were prepared. The observed thermal behaviour could be readily explained with the aid of a refinement of the qualitative model that was presented earlier [1]. All compounds were found to be mesogenic, and the observed mesophase was smectic Ad (i.e. a partially overlapping bilayer structure) in all cases. 相似文献
89.
Dynamical instability is studied in a deterministic dynamical system of Hamiltonian type composed of a tracer particle in a fluid of many particles. The tracer and fluid particles are hard balls (disks, in two dimensions, or spheres, in three dimensions) undergoing elastic collisions. The dynamical instability is characterized by the spectrum of Lyapunov exponents. The tracer particle is shown to dominate the Lyapunov spectrum in the neighborhoods of two limiting cases: the Lorentz-gas limit in which the tracer particle is much lighter than the fluid particles and the Rayleigh-flight limit in which the fluid particles have a vanishing radius and form an ideal gas. In both limits, a gap appears in the Lyapunov spectrum between the few largest Lyapunov exponents associated with the tracer and the rest of the Lyapunov spectrum. 相似文献
90.
Ring‐Closing and Cross‐Metathesis with Artificial Metalloenzymes Created by Covalent Active Site‐Directed Hybridization of a Lipase 下载免费PDF全文
Dr. Manuel Basauri‐Molina Dide G. A. Verhoeven Arnoldus J. van Schaik Henk Kleijn Prof. Dr. Robertus J. M. Klein Gebbink 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(44):15676-15685
A series of Grubbs‐type catalysts that contain lipase‐inhibiting phosphoester functionalities have been synthesized and reacted with the lipase cutinase, which leads to artificial metalloenzymes for olefin metathesis. The resulting hybrids comprise the organometallic fragment that is covalently bound to the active amino acid residue of the enzyme host in an orthogonal orientation. Differences in reactivity as well as accessibility of the active site by the functionalized inhibitor became evident through variation of the anchoring motif and substituents on the N‐heterocyclic carbene ligand. Such observations led to the design of a hybrid that is active in the ring‐closing metathesis and the cross‐metathesis of N,N‐diallyl‐p‐toluenesulfonamide and allylbenzene, respectively, the latter being the first example of its kind in the field of artificial metalloenzymes. 相似文献