全文获取类型
收费全文 | 212篇 |
免费 | 6篇 |
国内免费 | 1篇 |
专业分类
化学 | 164篇 |
力学 | 2篇 |
数学 | 17篇 |
物理学 | 36篇 |
出版年
2021年 | 2篇 |
2020年 | 2篇 |
2016年 | 4篇 |
2015年 | 3篇 |
2014年 | 7篇 |
2013年 | 13篇 |
2012年 | 7篇 |
2011年 | 12篇 |
2010年 | 10篇 |
2009年 | 8篇 |
2008年 | 13篇 |
2007年 | 12篇 |
2006年 | 15篇 |
2005年 | 8篇 |
2004年 | 14篇 |
2003年 | 8篇 |
2002年 | 8篇 |
2001年 | 2篇 |
1999年 | 2篇 |
1998年 | 2篇 |
1997年 | 3篇 |
1995年 | 2篇 |
1993年 | 3篇 |
1991年 | 3篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 4篇 |
1984年 | 3篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1980年 | 5篇 |
1979年 | 4篇 |
1978年 | 1篇 |
1977年 | 5篇 |
1976年 | 2篇 |
1975年 | 1篇 |
1974年 | 3篇 |
1973年 | 1篇 |
1969年 | 1篇 |
1937年 | 1篇 |
1934年 | 1篇 |
1925年 | 1篇 |
1923年 | 2篇 |
1920年 | 2篇 |
1908年 | 2篇 |
1907年 | 1篇 |
1893年 | 1篇 |
排序方式: 共有219条查询结果,搜索用时 15 毫秒
181.
182.
183.
Electrochemical Behaviour of HOPG and CVD‐Grown Graphene Electrodes Modified with Thick Anthraquinone Films by Diazonium Reduction
下载免费PDF全文
![点击此处可从《Electroanalysis》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Elo Kibena Margus Marandi Väino Sammelselg Kaido Tammeveski Bjarke B. E. Jensen Anders B. Mortensen Mie Lillethorup Mikkel Kongsfelt Steen U. Pedersen Kim Daasbjerg 《Electroanalysis》2014,26(12):2619-2630
Highly oriented pyrolytic graphite (HOPG) and graphene grown on Ni (Ni‐Gra) or Cu (Cu‐Gra) by chemical vapour deposition were modified with thick anthraquinone (AQ) films (7?60 nm) by redox grafting of the pertinent diazonium salt. Glassy carbon (GC) electrodes were used for comparison. The AQ‐modified GC electrodes showed excellent blocking properties towards the Fe(CN)63?/4? redox probe, although it was noted that in the case of Ni‐Gra and Cu‐Gra, the blocking ability depended strongly on the underlying substrate. Oxygen reduction studies revealed good electrocatalytic activity of AQ‐modified HOPG, Ni‐Gra, and Cu‐Gra, compared with the bare electrodes. 相似文献
184.
Mie KodaniAyumi Takamori Kazuo TakimiyaYoshio Aso Tetsuo Otsubo 《Journal of solid state chemistry》2002,168(2):582-589
Seven conductive radical cation salts based on MDSe-TSF (methylenediselenotetraselenafulvalene) have been synthesized by electrocrystallization in the presence of Cl−, Br−, I3−, I2Br−, PF6−, ClO4−, and Cu(NCS)2− counter anions. The crystal appearances of these salts fairly depend on the anions employed. X-ray crystallographic analyses have revealed that the PF6 and ClO4 salts in the shape of brown thin plates adopt the θ-type structures characterized by the herringbone arrangement of donor stacks, whereas the Cl and Br salts in the shape of black thick plates favor the κ-type structures with the orthogonal arrangement of donor dimers. Regardless of different crystal appearances or crystal packing patterns, all these salts show high conductivity (>102 S cm−1) at room temperature and retain metallic properties down to 4.2 K. Of them, the Br salt shows a weak but distinct diamagnetic shielding signal below 4 K in the dc magnetization measurement under zero-field-cooled (ZFC) condition, suggesting a sign of superconductivity. The band calculations of both PF6 and Br salts demonstrate closed Fermi surfaces indicative of two-dimensional molecular conductors. 相似文献
185.
Dr. Mie Andersen Dr. Andrew J. Medford Prof. Jens K. Nørskov Prof. Dr. Karsten Reuter 《Angewandte Chemie (International ed. in English)》2016,55(17):5210-5214
Bifunctional coupling of two different catalytic site types has often been invoked to explain experimentally observed enhanced catalytic activities. We scrutinize such claims with generic scaling‐relation‐based microkinetic models that allow exploration of the theoretical limits for such a bifunctional gain for several model reactions. For sites at transition‐metal surfaces, the universality of the scaling relations between adsorption energies largely prevents any improvements through bifunctionality. Only the consideration of systems that involve the combination of different materials, such as metal particles on oxide supports, offers hope for significant bifunctional gains. 相似文献
186.
Proton beam is useful to target tumor tissue sparing normal cells by allowing precise dose only into tumor cells. However, the cellular and molecular mechanisms by which proton beam induces tumor cell death are still undefined. We irradiated three different tumor cells (LLC, HepG2, and Molt-4) with low energy proton beam (35 MeV) with spread out Bragg peak (SOBP) in vitro, and investigated cell death by MTT or CCK-8 assay at 24 h after irradiation. LLC and HepG2 cells were sensitive to proton beam at over 10 Gy to induce apoptosis whereas Molt-4 showed rather low sensitivity. Relative biological effectiveness (RBE) values for the death rate relative to gamma-ray were ranged from 1.1 to 2.3 in LLC and HepG2 but from 0.3 to 0.7 in Molt-4 at 11 d after irradiation by colony formation assay. The typical apoptotic nuclear DNA morphological pattern was observed by staining with 4'-6-diamidino-2-phenylindole (DAPI). Tiny fragmented DNA was observed in HepG2 but not in Molt-4 by the treatment of proton in apoptotic DNA fragment assay. By FACS analysis after stained with FITC-Annexin-V, early as well as median apoptotic fractions were clearly increased by proton treatment. Proton beam-irradiated tumor cells induced a cleavage of poly (ADP-ribose) polymerase-1 (PARP-1) and procaspases-3 and -9. Activity of caspases was highly enhanced after proton beam irradiation. Reactive oxygen species (ROS) were significantly increased and N-acetyl cysteine pretreatment restored the apoptotic cell death induced by proton beam. Furthermore, p38 and JNK but not ERK were activated by proton and dominant negative mutants of p38 and JNK revived proton-induced apoptosis, suggesting that p38 and JNK pathway may be activated through ROS to activate apoptosis. In conclusion, our data clearly showed that single treatment of low energy proton beam with SOBP increased ROS and induced cell death of solid tumor cells (LLC and HepG2) in an apoptotic cell death program by the induction of caspases activities. 相似文献
187.
Povilas?Mie?inskas Konstantinas?Leinartas Virginija?Uksien? Eimutis?JuzeliūnasEmail author 《Journal of Solid State Electrochemistry》2007,11(7):909-913
The study demonstrated a possibility to sense the activity of microorganisms on metals in situ under atmosphere conditions
using a quartz crystal microbalance (QCM) as a sensitive mass change detector. Other innovative aspects of the QCM application
include long-term monitoring (over month), taking count of the influence of atmospheric pressure and application of Al-glued
foil electrodes. The research subject was aluminium colonisation by Aspergillus niger Tiegh., a filamentous ascomycete fungus. The difference between the QCM data for abiotic and biotic samples reflected microbiological
activity, which resulted in exponential mass gain during exposure. The increase in mass was due to various phenomena, i.e.
development of biomass, secretion of metabolites, water uptake by the colony and microbially induced corrosion. The glued
foil method demonstrated a possibility to expand the scope of the QCM studies from evaporated, sputtered or electroplated
materials to those, from which thin foils may be produced.
Dedicated to Professor Dr. Algirdas Vaškelis on the occasion of his 70th birthday. 相似文献
188.
189.
Satoshi Yamazaki Kenji Ohoyama Masaki Ichihara Yutaka Ueda 《Journal of solid state chemistry》2010,183(7):1496-1503
V4O9: A missing link of Wadsley phases has been successfully synthesized by using sulfur as a reducing agent at a low temperature and its structure has been determined by combining electron, X-ray and neutron diffractions. V4O9 has an orthorhombic Cmcm structure and the lattice parameters are a=10.356(2) Å, b=8.174(1) Å and c=16.559(3) Å at room temperature. The structure is composed of shared edges and corners of three types of polyhedra; a VO6 distorted octahedron, a VO5 pyramid and a VO4 tetrahedron. The structure of V4O9 is very similar to that of vanadyl pyrophosphate (VO)2P2O7 which has PO4 tetrahedra instead of VO4 tetrahedra. This indicates that V4O9 is a salt of pyro-ion [V2O7]4-; (VO)2V2O7. The magnetic properties of V4O9 have been investigated by magnetic susceptibility, high-field magnetization and inelastic neutron scattering measurements. V4O9 is a quantum spin system with a spin-gapped ground state. The excitation gap between the singlet ground state and the excited triplet state is approximately 73 K. The magnetic susceptibility behavior suggests that V4O9 is a spin-1/2 dimer system with significant interdimer interactions, as opposed to (VO)2P2O7, which is an alternating spin-1/2 chain system. This difference is thought to be due to the fact that VO4-mediated interactions are considerably weaker than PO4-mediated interactions. 相似文献
190.
David M. Hodgson Matthew L. Jones Andrew R. Cowley Osamu Ichihara 《Tetrahedron》2009,65(37):7825-6337
Additions of alkyl or aryl Grignard reagents, or pyridin-3-yl-lithiums or lithium alkoxides, to exo-5,6-epoxy-7-(tert-butoxycarbonyl)-2-tosyl-7-azabicyclo[2.2.1]hept-2-ene lead to 7-substituted-1-tosyl-3-azatricyclo[2.2.1.02,6]heptan-5-ols. Radical deoxygenations of 7-alkyl-1-tosyl-3-azatricyclo[2.2.1.02,6]heptan-5-ols give 7-alkyl-4-tosyl-2-azabicyclo[2.2.1]hept-5-enes, whereas 7-aryl-1-tosyl-3-azatricyclo[2.2.1.02,6]heptan-5-ols give 2-(arylmethyl)-5-tosyl-1,2-dihydropyridines. 相似文献