全文获取类型
收费全文 | 145篇 |
免费 | 10篇 |
专业分类
化学 | 48篇 |
力学 | 2篇 |
数学 | 49篇 |
物理学 | 56篇 |
出版年
2016年 | 4篇 |
2015年 | 6篇 |
2014年 | 7篇 |
2013年 | 8篇 |
2012年 | 6篇 |
2011年 | 4篇 |
2010年 | 3篇 |
2009年 | 4篇 |
2008年 | 6篇 |
2007年 | 3篇 |
2006年 | 7篇 |
2005年 | 4篇 |
2004年 | 3篇 |
2003年 | 4篇 |
2002年 | 4篇 |
2001年 | 6篇 |
2000年 | 4篇 |
1999年 | 2篇 |
1998年 | 2篇 |
1997年 | 3篇 |
1996年 | 2篇 |
1992年 | 2篇 |
1990年 | 2篇 |
1988年 | 1篇 |
1986年 | 2篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1979年 | 2篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 2篇 |
1975年 | 2篇 |
1974年 | 2篇 |
1973年 | 5篇 |
1972年 | 4篇 |
1971年 | 5篇 |
1970年 | 3篇 |
1969年 | 1篇 |
1968年 | 3篇 |
1967年 | 3篇 |
1965年 | 1篇 |
1964年 | 1篇 |
1963年 | 1篇 |
1935年 | 1篇 |
1929年 | 2篇 |
1887年 | 1篇 |
排序方式: 共有155条查询结果,搜索用时 46 毫秒
11.
S. Willmann A. Terenji J. Osterholz H.J. Schwarzmaier P. Hering 《Applied physics. B, Lasers and optics》2002,74(6):589-595
The aim of our studies was to develop a method to determine the absorption coefficient of a turbid medium in a reflection
geometry with small source–detector separations. Therefore, the time-integrated microscopic Beer–Lambert law (MBL) was modified
in order to obtain the absolute absorption coefficient from mean time of flight and dc-intensity measurements. The new technique
was evaluated using turbid phantoms having varying scattering (μs
′ between 0.2 and 2.2 mm-1) and absorbing properties (μa between 0.04 and 0.14 mm-1), comparable to many biological tissues at various source–detector separations between 3 and 11 mm. The measurements were
performed at a wavelength of 1064 nm. We found that this new method was able to determine the absolute absorption coefficient
of the selected phantoms with a standard error of less than 0.005 mm-1 over the range of optical properties investigated.
Received: 23 November 2001 / Revised version: 28 February 2002 / Published online: 14 May 2002 相似文献
12.
J. Göthel M. Ivanenko P. Hering W. Fuß K. L. Kompa 《Applied physics. B, Lasers and optics》1996,62(4):329-332
The isotope-selective multiphoton dissociation of CHClF2 in a multipass refocusing Herriott cell was used to enrich more than 4 moles of chlorodifluoromethane to 99.99% of12C isotopic purity. It is the largest isotope quantity ever separated by a laser process. A cw excited mechanically Q-switched CO2 laser, which delivers 16 mJ pulses at 5 kHz was used. The enrichment controlled by a mass-spectrometer and guided by a PC was run with a rate of 25 g12C per 24 h. 相似文献
13.
W. Trombik W. Trautmann F. Krug W. Dünnweber D. Konnerth W. Hering R. Singh D. Zeppenfeld 《Physics letters. [Part B]》1984,135(4):271-274
Using the out-of-plane γ-ray particle coincidence method we have measured the spin alignment Pzz of excited 12C(2+) nuclei from 12C+12C inelastic scattering in the energy range 16 MeV ? Ecm ? 33 MeV.Pzz varies strongly as a function of energy and angle. The correlation of resonant structures in the cross section with maxima of the alignment is particularly clear in mutual inelastic scattering and in θcm = 90° single inelastic scattering. 相似文献
14.
Franz Hering 《Israel Journal of Mathematics》1971,9(3):403-417
We investigate a class of bipartite graphs, whose structure is determined by a binary number.
The work for this research was supported by the Max Kade Foundation. 相似文献
15.
Single-step methods for the generation of patterned surfaces on hydrogels are presented. Poly(vinyl alcohol) films covalently bonded on glass cover slips and commercially available hydrogel-coated polystyrene plates were used as cell-repellent surfaces. Cell-adhesive domains were created by spotting dilute solutions of sodium hypochlorite onto the surfaces. Alternatively, domains supporting cell attachment were created by exposure to UV light from a xenon excimer lamp, employing a contact mask. Rat skeletal myoblast cells, HEK 293 human embryonic kidney cells and Caco-2 colon carcinoma cells adhered and spread exclusively on modified areas. The surfaces are durable for weeks under cell culture conditions and re-usable after removal of the cells by trypsin treatment. Arrays of adhesive spots seeded with cells at a low density permitted dynamic monitoring of cell proliferation. Selected colonies can be harvested from the surfaces by means of local trypsination. Thus, these techniques may provide useful tools for the isolation of clonal cell populations. Additionally, we demonstrate the possibility of surface-mediated gene delivery from the micro patterns. We show that DNA, complexed with a lipid reagent, can be adsorbed on modified poly(vinyl alcohol) coatings, resulting in spatially controlled adhesion and reverse transfection of HEK 293 cells. 相似文献
16.
Milena Hering 《Journal of Algebra》2010,323(4):1012-1017
We give a criterion for the section ring of an ample line bundle to be Koszul in terms of multigraded regularity. We discuss applications to adjoint bundles on toric varieties as well as to polytopal semigroup rings. 相似文献
17.
M. Haisch P. Hering W. Fuss W. Fabinski 《Isotopes in environmental and health studies》2013,49(2-3):247-251
We present a nondispersive infrared spectrometer (NDIRS) for the measurement of the 13CO2/12CO2-ratio in breath samples. A commercial NDIR spectrometer for CO2 concentration measurements in industrial process control was modified using two separate optical channels for the 13CO2 and 12CO2 detection. Cross interference due to overlapping absorption lines of both isotopic gases was successfully eliminated. The sensitivity of this device is ± 0.4‰ of the 13CO2/12CO2-ratio in a range of 2.5 to 5% of total CO2. This is sufficient for biomedical applications. Our spectrometer is small in size, cheap and simple to operate and thus a true alternative to isotope ratio mass spectrometers (IRMS). Several biomedical applications with breath samples were demonstrated and were compared in very good agreement with IRMS. 相似文献
18.
Dr. Christian Hering‐Junghans Max Thomas Dr. Alexander Villinger Prof. Dr. Axel Schulz 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(18):6713-6717
This work describes the synthesis and full characterization of elusive chloropnictenium ion salts of the type [RAr*N(SiMe)ECl][A] (RAr*=2,6‐(CHPh2)‐4‐R‐C6H2, R=Me, tBu; E=Sb, Bi; A?=GaCl4, Al(OCH(CF3)2)4). In these species the cation is significantly stabilized by weak arene interactions to flanking phenyl groups of the RAr* moiety. In this context the bonding situation has been studied by computational means and the reactivity towards the Lewis base 4‐dimethylaminopyridine (dmap) was investigated. 相似文献
19.
H. Sabana T. Fritsch M. Boyomo Onana O. Bouba P. Hering M. Mürtz 《Applied physics. B, Lasers and optics》2009,96(2-3):535-544
We describe a technique of simultaneous detection of 14NO and 15NO by means of Faraday Modulation Spectroscopy (FAMOS) based on a cw distributed feedback quantum cascade laser (QCL) operating near 5.4 μm. FAMOS is a spectroscopic method for selective, sensitive, and time-resolved detection of free radical molecules such as NO, in the mid-infrared spectral region. The selected spectral lines are the Q (1.5) for 15NO located at 1842.76 cm?1 and the P (9.5) for 14NO located at 1842.93 cm?1. The detection limit (1σ) of 6 ppb $/\sqrt{\mathrm{Hz}}$ for 15NO and 62 ppb $/\sqrt{\mathrm{Hz}}$ for 14NO has been achieved. The simultaneous detection was performed using a fast laser frequency switching between the two isotopologues with a time resolution of 2 s. The isotope ratio (δ 15N) has been determined with a precision (1σ) of 0.52‰ at 800-s averaging time for 100 ppm NO-gas with a time resolution of 2 s. δ 15N is determined after NO release from nitrite by chemical reduction with potassium iodine. 相似文献
20.
We report on spectroscopic real-time analysis of ethane traces in exhaled human breath. Ethane is considered the most important
volatile marker of free-radical induced lipid peroxidation and cell damage in the human body. Our measurements were carried
out by means of mid-infrared cavity leak-out spectroscopy in the 3 μm region, a cw variant of cavity ring-down spectroscopy.
The spectrometer is based on a CO overtone laser with tunable microwave sidebands. The resulting system proved to be an unique
tool with high sensitivity and selectivity for rapid and precise breath testing. With a 5 s integration time, we achieved
a detection limit on the order of 100 parts per trillion ethane in human breath. Thus, sample preconcentration is unnecessary.
Time-resolved monitoring of the decaying ethane fraction in breath after smoking a cigarette is demonstrated.
Received: 13 March 2001 / Published online: 9 May 2001 相似文献