全文获取类型
收费全文 | 247篇 |
免费 | 11篇 |
国内免费 | 5篇 |
专业分类
化学 | 107篇 |
力学 | 4篇 |
数学 | 82篇 |
物理学 | 70篇 |
出版年
2020年 | 4篇 |
2019年 | 3篇 |
2018年 | 2篇 |
2017年 | 4篇 |
2016年 | 7篇 |
2015年 | 6篇 |
2014年 | 10篇 |
2013年 | 7篇 |
2012年 | 20篇 |
2011年 | 18篇 |
2010年 | 12篇 |
2009年 | 7篇 |
2008年 | 9篇 |
2007年 | 8篇 |
2006年 | 11篇 |
2005年 | 9篇 |
2004年 | 9篇 |
2003年 | 6篇 |
2002年 | 7篇 |
2001年 | 3篇 |
2000年 | 4篇 |
1999年 | 5篇 |
1998年 | 3篇 |
1997年 | 4篇 |
1996年 | 5篇 |
1995年 | 3篇 |
1994年 | 7篇 |
1993年 | 2篇 |
1992年 | 8篇 |
1991年 | 7篇 |
1990年 | 4篇 |
1989年 | 5篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1985年 | 5篇 |
1984年 | 6篇 |
1983年 | 2篇 |
1982年 | 3篇 |
1981年 | 5篇 |
1980年 | 3篇 |
1979年 | 3篇 |
1978年 | 3篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1974年 | 1篇 |
1973年 | 2篇 |
1971年 | 1篇 |
1969年 | 1篇 |
1967年 | 1篇 |
1966年 | 2篇 |
排序方式: 共有263条查询结果,搜索用时 15 毫秒
241.
Comparison of antibody--antigen interactions on collagen measured by conventional immunological techniques and atomic force microscopy 总被引:2,自引:0,他引:2
Avci R Schweitzer M Boyd RD Wittmeyer J Steele A Toporski J Beech I Arce FT Spangler B Cole KM McKay DS 《Langmuir : the ACS journal of surfaces and colloids》2004,20(25):11053-11063
We have developed a means of using atomic force microscopy (AFM) to repeatedly localize a small area of interest (4 x 4 microm(2)) within a 0.5-cm(2) area on a heterogeneous sample, to obtain and localize high-resolution images and force measurements on nonideal samples (i.e., samples that better reflect actual biological systems, not prepared on atomically flat surfaces). We demonstrate the repeated localization and measurement of unbinding forces associated with antibody--antigen (ab--ag) interactions, by applying AFM in air and in liquid to visualize and measure polyclonal ab--ag interactions, using chicken collagen as a model system. We demonstrate that molecular interactions, in the form of ab--ag complexes, can be visualized by AFM when secondary antibodies are conjugated to 20-nm colloidal gold particles. We then compare those results with established immunological techniques, to demonstrate broader application of AFM technology to other systems. Data from AFM studies are compared with results obtained using immunological methods traditionally employed to investigate ab--ag interactions, including enzyme-linked immunosorbent assay, immunoblotting, and in situ immunofluorescence. Finally, using functionalized AFM tips with a flexible tether [poly(ethylene glycol) 800] to which a derivatized antibody was attached, we analyzed force curve data to measure the unbinding force of collagen antibody from its antigen, obtaining a value of approximately 90 +/- 40 pN with a MatLab code written to automate the analyses of force curves obtained in force--volume mode. The methodology we developed for embedded collagen sections can be readily applied to the investigation of other receptor--ligand interactions. 相似文献
242.
Constructing cospectral graphs 总被引:1,自引:0,他引:1
Some new constructions for families of cospectral graphs are derived, and some old ones are considerably generalized. One of our new constructions is sufficiently powerful to produce an estimated 72% of the 51039 graphs on 9 vertices which do not have unique spectrum. In fact, the number of graphs of ordern without unique spectrum is believed to be at leastn
3
g
–1 for some>0, whereg
n is the number of graphs of ordern andn 7. 相似文献
243.
244.
The GAMBIT Collaboration: Peter Athron Csaba Balázs Torsten Bringmann Andy Buckley Marcin Chrząszcz Jan Conrad Jonathan M. Cornell Lars A. Dal Joakim Edsjö Ben Farmer Paul Jackson Felix Kahlhoefer Abram Krislock Anders Kvellestad James McKay Farvah Mahmoudi Gregory D. Martinez Antje Putze Are Raklev Christopher Rogan Aldo Saavedra Christopher Savage Pat Scott Nicola Serra Christoph Weniger Martin White 《The European Physical Journal C - Particles and Fields》2017,77(8):568
One of the simplest viable models for dark matter is an additional neutral scalar, stabilised by a \(\mathbb {Z}_2\) symmetry. Using the GAMBIT package and combining results from four independent samplers, we present Bayesian and frequentist global fits of this model. We vary the singlet mass and coupling along with 13 nuisance parameters, including nuclear uncertainties relevant for direct detection, the local dark matter density, and selected quark masses and couplings. We include the dark matter relic density measured by Planck, direct searches with LUX, PandaX, SuperCDMS and XENON100, limits on invisible Higgs decays from the Large Hadron Collider, searches for high-energy neutrinos from dark matter annihilation in the Sun with IceCube, and searches for gamma rays from annihilation in dwarf galaxies with the Fermi-LAT. Viable solutions remain at couplings of order unity, for singlet masses between the Higgs mass and about 300 GeV, and at masses above \(\sim \)1 TeV. Only in the latter case can the scalar singlet constitute all of dark matter. Frequentist analysis shows that the low-mass resonance region, where the singlet is about half the mass of the Higgs, can also account for all of dark matter, and remains viable. However, Bayesian considerations show this region to be rather fine-tuned. 相似文献
245.
246.
John Conway John McKay Abdellah Sebbar 《Proceedings of the American Mathematical Society》2004,132(8):2233-2240
We characterize the 171 discrete subgroups of occurring in Monstrous Moonshine in terms of their group-theoretic properties alone.
247.
We report the results of experiments to estimate the moisture expansion of several modern and ancient clay brick ceramics from the time of manufacture. From these data we propose a new expansion law, in which the expansive strain increases as (age)(1/4) approximately. Such time dependence is consistent with a mechanism in which expansion arises from a diffusion-controlled rehydration reaction on a linear or low-dimension structure. Our results provide new guidance for the engineering design of masonry and suggest a possible new method for archaeological dating of ceramics. 相似文献
248.
A new ultrasonic method — thermoacoustic analysis — is reported for the detection of the added chemical preservatives in branded
milk. The nature of variation and shift in the thermal response of the acoustic parameters specific acoustic impedance, adiabatic
compressibility and Rao’s specific sound velocity for different samples of branded milk as compared to the chemical added
pure milk are explained as due to the presence of chemicals in these branded samples. 相似文献
249.
Ellegood J McKay RT Hanstock CC Beaulieu C 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2007,184(1):20-28
Although the diffusivity and anisotropy of water has been investigated thoroughly in ordered axonal systems (i.e., nervous tissue), there have been very few studies on the directional dependence of diffusion of metabolites. In this study, the mean apparent diffusion coefficient (Trace/3 ADC) and fractional anisotropy (FA) values of the intracellular metabolites N-acetyl aspartate (NAA), creatine and phosphocreatine (tCr), choline (Cho), taurine (Tau), and glutamate and glutamine (Glx) were measured parallel and perpendicular to the length of excised frog sciatic nerve using a water suppressed, diffusion-weighted, spin-echo pulse sequence at 18.8T. The degree of anisotropy (FA) of NAA (0.41+/-0.09) was determined to be less than tCr (0.59+/-0.07) and Cho (0.61+/-0.11), which is consistent with previously reported human studies of white matter. In contrast, Glx diffusion was found to be almost isotropic with an FA value of 0.20+/-0.06. The differences of FA between the metabolites is most likely due to their differing micro-environments and could be beneficial as an indicator of compartment specific changes with disease, information not readily available with water diffusion. 相似文献
250.