全文获取类型
收费全文 | 212篇 |
免费 | 9篇 |
国内免费 | 3篇 |
专业分类
化学 | 148篇 |
晶体学 | 1篇 |
力学 | 5篇 |
数学 | 26篇 |
物理学 | 44篇 |
出版年
2024年 | 1篇 |
2023年 | 6篇 |
2022年 | 3篇 |
2021年 | 4篇 |
2020年 | 14篇 |
2019年 | 8篇 |
2018年 | 8篇 |
2017年 | 2篇 |
2016年 | 5篇 |
2015年 | 6篇 |
2014年 | 8篇 |
2013年 | 13篇 |
2012年 | 14篇 |
2011年 | 17篇 |
2010年 | 9篇 |
2009年 | 6篇 |
2008年 | 14篇 |
2007年 | 13篇 |
2006年 | 13篇 |
2005年 | 10篇 |
2004年 | 7篇 |
2003年 | 4篇 |
2002年 | 6篇 |
2001年 | 2篇 |
2000年 | 4篇 |
1999年 | 3篇 |
1997年 | 1篇 |
1996年 | 2篇 |
1994年 | 2篇 |
1993年 | 1篇 |
1992年 | 2篇 |
1989年 | 1篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1970年 | 1篇 |
1937年 | 1篇 |
1934年 | 2篇 |
排序方式: 共有224条查询结果,搜索用时 15 毫秒
1.
A novel general-purpose interface-controller unit has been designed and applied in potentiometric analysis. The unit is operated by a personal microcomputer programmed in BASIC. The interface-controller permits direct reading of specific ion-electrodes and can activate, under program control, laboratory instruments such as motor-driven burettes. The interface-controller is expendable to 16 analogue input channels, 16 binary (logic) input lines and 16 control relays but requires only one microcomputer I/O port (a total of 9 I/O lines) to handle all operations. Analogue to digital conversion is realized by counting, with the microcomputer, the output frequency of an analogue-to-frequency converter. This inexpensive method is effective in rejecting interfering signals such as power-line interference. The system has been applied in potentiometric titration analysis for determining the apparent dissociation constants of carbonic acid in sea-water and Dead Sea brines, and for ammonia determination with a gas-sensing electrode. 相似文献
2.
A new approach to micropatterning is demonstrated. The approach is based on driving an electrochemical process at the solid-liquid interface through the formation of a flux of ions from a micropipet that is held in close proximity to the surface. The flux of ions is generated by the so-called potential assisted ion transfer at the interface between two immiscible electrolyte solutions (ITIES). As a model system, the local deposition of silver was examined. Specifically, a constant potential, which was applied to a micropipet filled with an aqueous solution of silver ions, caused the transfer of Ag(+) into the outer nitrobenzene (NB) solution that consisted of an electrolyte, tetrabutylammonium tetrakis[4-chlorophenyl]borate (TBATPBCl). To facilitate the transfer of silver ions a macrocyclic ligand, that is, dibenzo-24-crown-8 (DB24C8), was added to the organic phase. The Faradaic current of this micro-ITIES was used as a means of controlling the tip-surface distance in scanning electrochemical microscopy (SECM) and depositing silver microstructures on a gold substrate. 相似文献
3.
Eyal Jakobs Yael Hanein 《Colloids and surfaces. A, Physicochemical and engineering aspects》2006,290(1-3):33-40
A novel method for fabricating micrometer sized gel patterns is described. The presented method involves spin-coating a pre-gel solution on a surface that was chemically treated to modulate its surface energy, creating highly hydrophobic areas on a hydrophilic substrate. Following spin-coating, the gel solution self organizes on the hydrophilic sites. This method offers the advantages of high resolution, self-alignment to pre-patterned electrodes, and a simple straightforward fabrication process. Minimum feature size achieved was approximately 20 μm. The characteristic shrinking and swelling times of gel patterns were measured and found to be around 0.6 s for swelling and 2 s for shrinking (for a 60 μm diameter gel) in agreement with the reduced response time expected for scaled down gel patterns. These results suggest the suitability of these gel patterns as valves or actuators in microfluidic devices. Micron-size gel patterns were also incorporated into microfluidic channels thus demonstrating a new approach to create simple, affordable, microfluidic devices, which incorporate “smart” hydrogels as building elements in a simple fashion. 相似文献
4.
Osman Dayan Muharrem Diner Bekir etinkaya Namk
zdemir Orhan Büyükgüngr 《Acta Crystallographica. Section C, Structural Chemistry》2006,62(8):m346-m348
The title complex, di‐μ‐chloro‐bis[chloro(η6‐p‐cymene)ruthenium(II)]–9H‐carbazole (1/2), [Ru2Cl4(C10H14)2]·2C12H9N, is composed of one [RuCl2(η6‐p‐cymene)]2 and two 9H‐carbazole molecules. There are one‐half of a dinuclear complex and one 9H‐carbazole molecule per asymmetric unit. In the dinuclear complex, each of the two crystallographically equivalent Ru atoms is in a pseudo‐tetrahedral environment, coordinated by a terminal Cl atom, two bridging Cl atoms and the aromatic hydrocarbon, which is linked in a η6 manner; the Ru⋯Ru separation is 3.688 (3) Å. The title complex has a crystallographic centre of symmetry located at the mid‐point of the Ru⋯Ru line. Intermolecular N—H⋯Cl and π–π stacking interactions are observed. These interactions form a four‐pointed star‐shaped ring and one‐dimensional linear chains of edge‐fused rings running parallel to the [100] direction, which stabilize the crystal packing. 相似文献
5.
Yael Diskin‐Posner Goutam Kumar Patra Israel Goldberg 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(6):m344-m346
The title compound, [5,10,15,20‐meso‐tetrakis(4‐hydroxyphenyl)porphyrinato‐κ4N]zinc(II) tris(dibenzo‐24‐crown‐8) methanol tetrasolvate, [Zn(C44H28N4O4)]·3C24H32O8·4CH4O, was synthesized and its molecular structure precisely characterized by low‐temperature single‐crystal analysis. All the components are involved in hydrogen bonding with each other, thus forming an extensively hydrogen‐bonded supramolecular lattice. The functionalized porphyrin moiety coordinates both equatorially and axially to the neighboring species. 相似文献
6.
7.
8.
Qiu-Cheng Chen Dr. Natalia Fridman Dr. Yael Diskin-Posner Prof. Dr. Zeev Gross 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(43):9481-9485
Palladium complexes of corrole and sapphyrin were prepared in high yield and fully characterized. The corrole provides a tetradentate/trianionic square planar coordination sphere for PdII, charge balanced by pyridinium. Both one and two PdII ions may be accommodated by the pentapyrrolic skeleton of the sapphyrin, and in each case the macrocycle acts as bidentate/monoanionic ligand and the inner-sphere square planar geometry is completed by allyl anions coordinated in an η3 fashion. NMR spectroscopy and X-ray crystallography data analyses uncovered the presence of interesting stereoisomers due to the flexibility of the ally ligands and also the pyrrole ring(s) that is/are not involved in metal binding. 相似文献
9.
Diğdem Erdener Çıralı Osman Dayan 《Phosphorus, sulfur, and silicon and the related elements》2013,188(7):1100-1107
10.
Dr. Ori Gidron Dr. Yael Diskin‐Posner Prof. Michael Bendikov 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(39):13140-13150
The extent of charge delocalization and of conjugation in oligofurans and oligothiophenes was studied by using mixed valence systems comprising oligofurans and oligothiophenes capped at both ends by ferrocenyl redox units. Using electrochemical, spectral, and computational tools, we find strong charge delocalization in ferrocene‐capped oligofurans which was stronger than in the corresponding oligothiophene systems. Spectroscopic studies suggest that the electronic coupling integral (Hab) is roughly 30–50 % greater for oligofuran‐bridged systems, indicating better energy matching between ferrocene units and oligofurans. The distance decay constant (damping factor), β, is similar for oligofurans (0.066 A?1) and oligothiophenes (0.070 A?1), which suggests a similar extent of delocalization in the bridge, despite the higher HOMO–LUMO gap in oligofurans. Computational studies indicate a slightly larger extent of delocalization in furan‐bridged systems compared with thiophene‐bridged systems, which is consistent with oligofurans being significantly more rigid and less aromatic than oligothiophenes. High charge delocalization in oligofurans, combined with the previously reported strong fluorescence, high mobility, and high rigidity of oligofuran‐based materials makes them attractive candidates for organic electronic applications. 相似文献