全文获取类型
收费全文 | 284篇 |
免费 | 33篇 |
国内免费 | 71篇 |
专业分类
化学 | 244篇 |
晶体学 | 8篇 |
力学 | 65篇 |
综合类 | 3篇 |
数学 | 12篇 |
物理学 | 56篇 |
出版年
2023年 | 7篇 |
2022年 | 6篇 |
2021年 | 16篇 |
2020年 | 15篇 |
2019年 | 11篇 |
2018年 | 5篇 |
2017年 | 14篇 |
2016年 | 15篇 |
2015年 | 14篇 |
2014年 | 22篇 |
2013年 | 26篇 |
2012年 | 18篇 |
2011年 | 27篇 |
2010年 | 9篇 |
2009年 | 16篇 |
2008年 | 8篇 |
2007年 | 16篇 |
2006年 | 11篇 |
2005年 | 11篇 |
2004年 | 21篇 |
2003年 | 8篇 |
2002年 | 8篇 |
2001年 | 6篇 |
2000年 | 16篇 |
1999年 | 7篇 |
1998年 | 7篇 |
1997年 | 8篇 |
1996年 | 6篇 |
1995年 | 3篇 |
1994年 | 7篇 |
1993年 | 5篇 |
1992年 | 3篇 |
1991年 | 4篇 |
1989年 | 4篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1985年 | 3篇 |
1984年 | 1篇 |
1979年 | 1篇 |
1977年 | 1篇 |
排序方式: 共有388条查询结果,搜索用时 31 毫秒
261.
Yi Xu Wenfeng Yang Ting Sun Longshao Li Qingru Tang 《Journal of Macromolecular Science: Physics》2013,52(7):516-526
The effects of different curing pressures on the structure and properties of bisphenol A type epoxy adhesive film (METLBOND 1515-4, Cytec Industries Inc. Germany) were investigated by differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), dynamic mechanical analysis (DMA), nano-indentation analysis, and tensile testing. When the curing pressure was increased from 0?MPa to 0.5?MPa FTIR showed that more rigid carbonyl groups were found in the polymers. In addition, the microscopic and macroscopic mechanical properties of the cured adhesive films were improved. Nano-indentation analysis showed that the elastic modulus of the cured product increased significantly, from 2.92?GPa to 3.49?GPa. However, the tensile tests showed that the breaking-elongation increased only slightly, from 3.10% to 3.73%, when the curing pressure was increased from 0?MPa to 0.5?MPa. DMA results showed that the crosslinking densities of the cured epoxy films were improved by the increased curing pressure. These results indicated that a higher modulus of the cured product could be gained by increasing the curing pressure appropriately. 相似文献
262.
Herein, we introduce the fabrication of a micro-perforated elastomeric poly(dimethylsiloxane) (PDMS) mask and employ it for
spatially defined surface modification. To fabricate the micro-perforated PDMS mask, high-aspect-ratio micro-pillar arrays
having millimeter scale height were first fabricated via direct photopolymerization using a thiol–ene-based UV-curable adhesive.
Square pillars (500 × 500 μm) and 200 μm circular pillars with 5 and 12.5 in the aspect ratios, respectively, were successfully
fabricated with high pattern fidelity, reaching 2.5mm in height. Next, using the micro-pillar-array platform as a master mold,
PDMS prepolymer was cast and polymerized to form an elastomeric PDMS mask having micro-perforation arrays. Alternating hydrophilic
and hydrophobic surfaces were successfully obtained by oxidizing PDMS-covered Si wafer with corona discharge. Spatially defined
chemical functionalities obtained by selective oxidation and subsequent silanization were clearly distinguished via colorimetric
detection methods employing ninhydrin and toluidine reagents. The micro-perforated elastomeric PDMS mask enables selective
modification of a surface without utilizing photoreactive chemicals and a photomask.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
263.
Application of temperature modulated dilatometry (TM DIL) to investigation on degradation of the adhesion between ceramic
films and the substrate is presented. Layers of titanium nitride deposited by plasma assisted physical vapour deposition (PA
PVD) methods on the Armco iron substrates were tested. This paper shows that the TM DIL method is helpful in determining the
usefulness of the titanium nitride covering of the cutting tools and machine parts.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
264.
B. Jancovici 《Journal of statistical physics》1977,17(5):357-370
The short-range behavior of the pair correlation function in a dense onecomponent plasma (jellium) is investigated. As an intermediate step, the short-range behavior of the classical pair correlation function is obtained. Actually, although the temperature and the density are assumed to be such that the thermodynamic properties are almost classical, quantum mechanics (tunnel effect) always dominates the pair correlation function at short distances. The quantum pair correlation function is calculated by treating the many-body quantum effects by a perturbation theory, and by using a semiclassical approximation based on path integrals. The results are applied to the computation of the nuclear reaction rate in dense stellar matter (pycnonuclear reactions).Laboratoire associé au Centre National de la Recherche Scientifique. 相似文献
265.
Alexandra Roos Costantino Creton Mikhail B. Novikov Mikhail M. Feldstein 《Journal of Polymer Science.Polymer Physics》2002,40(20):2395-2409
The adhesive properties of blends of high molecular weight poly(vinyl pyrrolidone) (PVP) and low molecular weight poly(ethylene glycol) (PEG) were systematically investigated with a probe test and correlated with their viscoelastic properties. The material parameters that were varied were the PEG content (31–41 wt %) and the hydration rate. The 36% PEG showed the best balance of properties for a pressure‐sensitive adhesive. At low debonding rates, the debonding took place through the formation of a fibrillar structure, whereas at high debonding rates, the debonding was brittle. This transition was attributed to the breakage and reformation of hydrogen bonds between PVP units and OH groups on PEG during the large strain of the polymer chains in elongation. This transition was observed, albeit shifted in frequency, for all three compositions, and the characteristic relaxation times of the hydrogen‐bonded network were estimated. A comparison between the tack properties of the adhesives and their linear viscoelastic properties showed a very strong decoupling between the small‐strain and large‐strain properties of the adhesive, which was indicative of a pronounced deviation from rubber elasticity in the behavior of the blends. This deviation, also seen during tensile tests, was attributed to the peculiar phase behavior of the blends. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 2395–2409, 2002 相似文献
266.
267.
Two new devices were developed to provide accurate measurements of both the contact area and the tack strength of pressure-sensitive adhesives (PSAs). The first one is the "mechano-optical tack tester" (MOTT), which was designed to apply controlled contact pressure by means of a quartz prism probe, for determined contact times, onto the surfaces of PSA samples. The contact area is measured by the reflection of light at the quartz probe surface, which is in contact with the adhesive. The second device is an "acoustic contact tester" (ACT) that measures the tack strength and the contact area between a silicate glass and an adhesive by the reflection of an acoustic wave. Two ultrasonic sensors of different acoustic wavelengths have been built in order to study the scaling effects of the contact kinetics between an adhesive and the probe. MOTT and ACT experiments on a commercial PSA show that the contact area is the main parameter that governs the tack properties of the PSA. The experiments and the modeling point out that the contact area depends on the compression stress, the roughness, the thickness, and the Young's modulus of the PSA. However, comparison of contact kinetics from MOTT and ACT experiments show that the contact area is a subjective parameter that depends on the wavelength of the reflected beam used for its measurement. 相似文献
268.
文中讨论了聚合物环境响应的多样性,此响应性可借表面改性和形成多组分聚合物以结构参数而有效地控制。响应性与生物医学材料的血液相容性及既适合极性又可用于非极性基材的粘合剂的智能特性相关。 相似文献
269.
L. G. Suttorp 《Journal of statistical physics》1992,66(5-6):1343-1357
The correlations of the electric potential fluctuations in a classical one-component plasma are studied for large distances between the observation points. The two-point correlation function for these fluctuations is known to decay slowly for large distances, even if exponential clustering holds for the charge correlation functions. In this paper the asymptotic behavior of the generalk-point electric potential correlation functions is analyzed. Each of these correlation functions can be split into a reducible part, which is given by a sum of products of lower-order correlation functions, and a remaining irreducible part. It is shown, on the basis of an exponential clustering hypothesis for the charge correlation functions, that for allk3 the irreducible parts of the electric potential correlation functions decay faster than any inverse power of the distance, if one or more of the observation points move far away from the others. Hence, the two-point electric potential correlation function is the only one with a slow algebraic decay. The same statement holds for the correlation functions of the electric field fluctuations. 相似文献
270.
The Scanning Kelvin Probe is introduced as a real time non-destructive in situ technique for the detection of de-adhesion at adhesive/metal oxide interfaces. Iron substrates and an epoxy adhesive served as model systems. Iron surfaces were coated with ultra-thin organosilane plasma polymer films from a microwave discharge and 3-(trimethoxysilyl)-propylamine films from dilute water based solutions. Surface and film characterisation was done by means of atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and infrared reflection absorption spectroscopy (IRRAS). The effect of these interfacial films on the stability of the adhesive/metal joint was studied in corrosive environments. The Scanning Kelvin Probe allows the measurement of electrode potentials at buried polymer/metal interfaces with a spatial resolution of about 100 m. The electrode potential characterises the reactivity of the interface. Moreover, by the variation of the oxygen partial pressure in the measurement chamber, local anodes and cathodes underneath the polymer can be distinguished. The kinetics of electrochemical de-adhesion can be effectively slowed down by thin 3-(trimethoxysilyl)-propylamine films at the interface. The effect of the adhesion promoter can be further improved when a thin SiOx layer, which inhibits electron transfer reactions, and is deposited on the iron surface prior to coating with the adhesion promoter.This paper is dedicated to Mike Owen on occasion of his winning the DeBruyn medal, the first silicon chemist to do so. 相似文献