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排序方式: 共有196条查询结果,搜索用时 15 毫秒
111.
Dietmar Lenko Sandra Schlögl Rebecca Kramer Wolfgang Kern Raimund Schaller Armin Holzner 《Macromolecular Symposia》2012,311(1):9-17
Summary: The present work is focused on the characterization of the surface properties and the mechanical properties of chlorinated polyisoprene films. Cross-linked polyisoprene films were treated with acidified hypochlorite solution and the influence of the chlorination time on the surface properties was determined by spectroscopic techniques including FT-IR spectroscopy and X-ray photoelectron spectroscopy (XPS). The surface morphology was investigated by scanning electron microscopy (SEM), optical microscopy and contact angle measurements. In addition, the effect of the chlorination time on the tensile strength and ageing stability of natural rubber latex gloves was investigated. 相似文献
112.
The contractile ability of active materials relies on the interplay of force-exerting and force-bearing structures. However, the complexity of interactions and limited parameter control of many model systems are major obstacles in advancing our understanding of the underlying fundamental principles. To shed light on these principles we introduce and analyse a minimal reconstituted system, consisting of highly concentrated actin filaments that are crosslinked by α-actinin and actively transported in the two-dimensional geometry of a motility assay. This minimal system actively compacts and evolves into highly compact fibres that exceed the length of the individual filaments by two orders of magnitude. We identify the interplay between active transport and crosslinking to be responsible for the observed active compaction. This enables us to control the structure and the length scale of active compaction. 相似文献
113.
R. Leitsmann O. B?hm Ph. Pl?nitz C. Radehaus M. Schaller M. Schreiber 《Surface science》2010,604(19-20):1808-1812
We report ab initio investigations for the adsorption mechanisms of fluorocarbon polymers at ultra low-k (ULK) surfaces. As prototypical example we study a C2F4-molecule adsorbed at a passivated SiO2:CH3(001) surface. The calculated adsorption energies between 1.37 and 1.95 eV imply a chemisorption bonding mechanism. The detailed analysis of all investigated structures provides a simple rule to make a rough estimate of the stability of adsorbed fluorocarbon polymers. In addition, an adsorption pathway is proposed and used to suggest a possible adsorption mechanism, triggered by an electron transfer between the ULK surface and the C2F4 molecule. 相似文献
114.
We analyze distributions of exciton populations in PbSe nanocrystal (NC) ensembles as a function of excitation wavelength. For photon energies that result in carrier multiplication, these distributions are non-Poissonian and are characterized by two dominant exciton multiplicities that are determined by the ratio of photon energy to NC energy gap. For certain photon energies, we produce photoexcited NC ensembles with a nearly pure single multiplicity that can be tuned from 1 to 7. This result can find applications ranging from lasing and nonlinear optics to photovoltaics and photocatalysis. 相似文献
115.
The focus of this review is on current developments in monolithic stationary phases for the fast analysis of inorganic ions and other small molecules in ion chromatography (IC) and capillary electrochromatography (CEC), concentrating in particular on the properties of organic (polymer) monolithic materials in comparison to inorganic (silica-based) monoliths. The applicability of these materials for fast IC is discussed in the context of recent publications, including the range of synthesis and modification procedures described. While commercial monolithic silica columns already show promising results on current IC instrumentation, polymer-based monolithic stationary phases are currently predominantly used in the capillary format on modified micro-IC systems. However, they are beginning to find application in IC particularly under high pH conditions, with the potential to replace their particle-packed counterparts. 相似文献
116.
Synthesis, NMR Spectra and Structure of [(CH3)2Ga{μ‐P(H)Si(CH3)3}2Ga(CH3)2{μ‐P(Si(CH3)3)2}Ga(CH3)2] The title compound has been prepared in good yield by the reaction of [Me2GaOMe]3 (Me = CH3) with HP(SiMe3)2 in toluene (ratio 1 : 1,1) and purified by crystallization from pentane or toluene, respectively. This organogallium compound forms (Ga–P)3 ring skeletons with one Ga–P(SiMe3)2–Ga and two Ga–P(H)SiMe3–Ga bridges and crystallizes in the monoclinic space group C2/c. The known homologous Al‐compound is isotypic, both (MIII–P)3 heterocycles have twist‐conformations, the ligands of the monophosphane bridges have trans arrangements. 相似文献
117.
Ohne Zusammenfassung 相似文献
118.
Johannes K. Schaller Christo G. Stojanoff 《Particle & Particle Systems Characterization》1996,13(3):196-204
A Diesel spray injected into a high-pressure test chamber was investigated with two different holographic techniques. The usual off-axis recording geometry was used to investigate the very early beginning of the injection. Double pulsing of the recording laser facilitated velocity measurements. By using two different reference angles for the two recording the two images can be separated upon reconstruction of the holograms. Thus superior image quality could be achieved. Processes leading to jet formation could be identified: the spray tip is periodically axially decelerated and radially accelerated. Consequently, liquid moves at the tip off axis. The spray consists of fast central region surrounded by a slower outer jet region. The outer jet region exhibits periodic droplet concentration fluctuations which are interpreted as a result of the periodic processes at the spray tip. Some high concentration regions in the outer jet region were investigated using a dark-field holographic technique. This technique permits single droplet velocity measurements and local droplet concentration determination at extremely high droplet concentrations. The most important result of these investigations is that no correlation between the local droplet concentration and the droplet velocity could be found. 相似文献
119.
S. Tresch R. Jacot-Guillarmod F. Mulhauser L.A. Schaller L. Schellenberg H. Schneuwly Y.-A. Thalmann A. Werthmüller 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1998,2(2):93-97
The present status of research of muon transfer from the ground state of muonic protium to 4He is reviewed. The analysis of a recent measurement in a triple gas mixture of H2+4He+Ne at 15 bar and room temperature is presented and the result is compared to the existing experimental and theoretical
rates. The average muon transfer rate from protium to 4He determined from all lifetime measurements is .
Received: 22 January 1998 / Revised: 4 March 1998 / Accepted: 31 March 1998 相似文献
120.
Werthmüller A. Adamczak A. Jacot-Guillarmod R. Mulhauser F. Piller C. Schaller L. A. Schellenberg L. Schneuwly H. Thalmann Y. -A. Tresch S. 《Hyperfine Interactions》1996,101(1):271-275
To investigate the energy dependence of muon transfer to oxygen, we performed measurements in gaseous mixtures of hydrogen and oxygen. The time distributions of the muonic oxygen X-rays showed the same structure as the one observed earlier in H2+SO2 mixtures. In the delayed part of these distributions, one can distinguish a short-time and a long-time component. From the latter, we deduced the transfer rates from thermalized muonic protium, respectively deuterium, to oxygen. The short-time component can be interpreted as being due to muon transfer from epithermal muonic hydrogen atoms. The time parameters are characteristic for the deceleration process as well as for energy-dependent transfer rates. With results of recent research on the formation and the thermalization of muonic hydrogen, we performed Monte Carlo simulations in order to test the hypothesis of an energy-dependent transfer rate. 相似文献