全文获取类型
收费全文 | 90篇 |
免费 | 1篇 |
国内免费 | 3篇 |
专业分类
化学 | 63篇 |
数学 | 21篇 |
物理学 | 10篇 |
出版年
2022年 | 1篇 |
2018年 | 1篇 |
2015年 | 1篇 |
2014年 | 2篇 |
2013年 | 6篇 |
2012年 | 5篇 |
2011年 | 10篇 |
2010年 | 1篇 |
2009年 | 1篇 |
2008年 | 4篇 |
2007年 | 3篇 |
2006年 | 8篇 |
2005年 | 8篇 |
2004年 | 5篇 |
2003年 | 5篇 |
2002年 | 2篇 |
2001年 | 2篇 |
2000年 | 7篇 |
1999年 | 1篇 |
1997年 | 2篇 |
1994年 | 1篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1988年 | 1篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 3篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1980年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1963年 | 1篇 |
1962年 | 1篇 |
排序方式: 共有94条查询结果,搜索用时 15 毫秒
41.
Neil D. Feasey Nigel J. Forrow Graeme Hogarth Selby A.R. Knox Kirsty A. Macpherson Michael J. Morris A. Guy Orpen 《Journal of organometallic chemistry》1984,267(3):c41-c44
UV irradiation of [Ru2(CO)4(η-C5H5)2] yields the tri- and tetra-ruthenium complexes [Ru2(CO)4(η-C5H5){η-C5H4Ru(CO)2(η-C5H5)}] and [Ru4(CO)6(μ3-C5H4)2(η-C5H5)2]. The μ3-C5H4 ligand in the latter has been characterised through an X-ray diffraction study on [Ru4(CO)5{P(OMe)3}(μ3-C5H4)2(η-C5H5)2]. 相似文献
42.
Paul A. Liddell John P. Sumida Alisdair N. Macpherson Lori Noss Gilbert R. Seely Kristine N. Clark Ana L. Moore Thomas A. Moore Devens Gust 《Photochemistry and photobiology》1994,60(6):537-541
Abstract Porphyrin-C60 dyads in which the two chromophores are linked by a bicyclic bridge have been synthesized using the Diels-Alder reaction. The porphyin singlet lifetimes of both the zinc (Pzn -C60 ) and free base (P-C60 ) dyads, determined by time-resolved fluorescence measurements, are ≦17 ps in toluene. This substantial quenching is due to singlet-singlet energy transfer to C60 The lifetime of Pzn-1 C60 is -5 ps in toluene, whereas the singlet lifetime of an appropriate C60 model compound is 1.2 ns. This quenching is attributed to electron transfer to yield Pzn bull; +-C60 bull; -. In toluene, P-1 C60 is unquenched; the lack of electron transfer is due to unfavorable thermodynamics. In this solvent, a transient state with an absorption maximum at 700 ran and a lifetime of-10 μs was detected using transient absorption methods. This state was quenched by oxygen, and is assigned to the C60 triplet. In the more polar benzonitrile, P-1 C60 underoes photoinduced electron transfer to give P• + -C60 bull; -. The electron transfer rate constant is −2 × 1011 s−1 . 相似文献
43.
Aullón G Bernhardt PV Bozoglian F Font-Bardía M Macpherson BP Martínez M Rodríguez C Solans X 《Inorganic chemistry》2006,45(21):8551-8562
We have investigated the isomeric distribution and rearrangement of complexes of the type [CoXLn]2+,3+ (where X = Cl-, OH-, H2O, and Ln represents a pentadentate 13-, 14-, and 15-membered tetra-aza or diaza-dithia (N4 or N2S2) macrocycle bearing a pendant primary amine). The preparative procedures for chloro complexes produced almost exclusively kinetically preferred cis isomers (where the pendant primary amine is cis to the chloro ligand) that can be separated by careful cation-exchange chromatography. For L13 and L14 the so-called cis-V isomer is isolated as the kinetic product, and for L15 the cis-VI form (an N-based diastereomer) is the preferred, while for the L14(S) complex both cis-V and trans-I forms are obtained. All these complexes rearrange to form stable trans isomers in which the pendent primary amine is trans to the monodentate aqua or hydroxo ligand, depending on pH and the workup procedure. In total 11 different complexes have been studied. From these, two different trans isomers of [CoClL14(S)]2+ have been characterized crystallographically for the first time in addition to a new structure of cis-V-[CoClL14(S)]2+; all were isolated as their chloride perchlorate salts. Two additional isomers have been identified and characterized by NMR as reaction intermediates. The remaining seven forms correspond to the complexes already known, produced in preparative procedures. The kinetic, thermal, and baric activation parameters for all the isomerization reactions have been determined and involve large activation enthalpies and positive volumes of activation. Activation entropies indicate a very important degree of hydrogen bonding in the reactivity of the complexes, confirmed by density functional theory studies on the stability of the different isomeric forms. The isomerization processes are not simple and even some unstable intermediates have been detected and characterized as part of the above-mentioned 11 forms of the complexes. A common reaction mechanism for the isomerization reactions has been proposed for all the complexes derived from the observed kinetic and solution behavior. 相似文献
44.
In this paper we develop a structure theory for transitive permutationgroups definable in o-minimal structures. We fix an o-minimalstructure M, a group G definable in M, and a set and a faithfultransitive action of G on definable in M, and talk of the permutationgroup (G, ). Often, we are concerned with definably primitivepermutation groups (G, ); this means that there is no propernon-trivial definable G-invariant equivalence relation on ,so definable primitivity is equivalent to a point stabiliserG being a maximal definable subgroup of G. Of course, sinceany group definable in an o-minimal structure has the descendingchain condition on definable subgroups [23] we expect many questionson definable transitive permutation groups to reduce to questionson definably primitive ones. Recall that a group G definable in an o-minimal structure issaid to be connected if there is no proper definable subgroupof finite index. In some places, if G is a group definable inM we must distinguish between definability in the full ambientstructure M and G-definability, which means definability inthe pure group G:= (G, .); for example, G is G-definably connectedmeans that G does not contain proper subgroups of finite indexwhich are definable in the group structure. By definable, wealways mean definability in M. In some situations, when thereis a field R definable in M, we say a set is R-semialgebraic,meaning that it is definable in (R, +, .). We call a permutationgroup (G, ) R-semialgebraic if G, and the action of G on canall be defined in the pure field structure of a real closedfield R. If R is clear from the context, we also just writesemialgebraic. 相似文献
45.
Yi‐Chieh Chen Robert J. Young Julie V. Macpherson Neil R. Wilson 《Journal of Raman spectroscopy : JRS》2011,42(6):1255-1262
We report on investigations upon a surface‐enhanced Raman scattering (SERS) substrate produced from a two‐dimensional single‐walled carbon nanotube (SWNT) network decorated with Ag nanoparticles. Using the strong and unique Raman spectrum of SWNTs as a reference, the SWNT/Ag nanostructure can be considered to provide two regions: one with an ultrasensitive SERS response for single‐molecule SERS (SMSERS) study; and another with uniform SERS enhancement over an area of several square millimeters for general SERS measurements. We report the appearance of an anomalous Raman feature at around 2180 cm−1 in the high‐sensitivity region which exhibits the characteristics of SMSERS. The SERS performance of the uniform area was characterized using pyridine vapor adsorbed onto the substrate. The presence of the SWNT/Ag nanostructure enhanced the Raman intensity by over seven orders of magnitude, a factor comparable to or exceeding that obtained on SERS substrates reported by other groups. The results indicate great potential to produce highly sensitive, uniform SERS substrates via further fine‐tuning of the nanostructure. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
46.
Electrochemical impedance spectroscopy at single-walled carbon nanotube network ultramicroelectrodes
Ioana Dumitrescu Patrick R. Unwin Julie V. Macpherson 《Electrochemistry communications》2009,11(11):2081-2084
Electrochemical impedance spectroscopy (EIS), coupled with chemical vapour deposition (CVD) grown single-walled carbon nanotube (SWNT) network disk-shaped ultramicroelectrodes (UMEs), gives stable, very well-defined and highly reproducible EIS responses for electrolysis of a simple outer sphere redox couple (FcTMA+/2+). The resulting EIS data can be fitted accurately using a simple electrical circuit model, enabling information on double-layer capacitance, diffusion coefficient of the electroactive species and the rate constant of ET (k0) to be extracted in a single EIS experiment. These values are replicated for a range of mediator concentrations and UME sizes (in the range 25–100 μm diameter) demonstrating the robustness of the method. These initial studies bode well for impedance based electroanalysis using SWNT network UMEs. 相似文献
47.
Gollapalli DR Macpherson IS Liechti G Gorla SK Goldberg JB Hedstrom L 《Chemistry & biology》2010,17(10):1084-1091
The protozoan parasite Cryptosporidium parvum is a major cause of gastrointestinal disease; no effective drug therapy exists to treat this infection. Curiously, C. parvum IMPDH (CpIMPDH) is most closely related to prokaryotic IMPDHs, suggesting that the parasite obtained its IMPDH gene via horizontal transfer. We previously identified inhibitors of CpIMPDH that do not inhibit human IMPDHs. Here, we show that these compounds also inhibit IMPDHs from Helicobacter pylori, Borrelia burgdorferi, and Streptococcus pyogenes, but not from Escherichia coli. Residues Ala165 and Tyr358 comprise a structural motif that defines susceptible enzymes. Importantly, a second-generation CpIMPDH inhibitor has bacteriocidal activity on H. pylori but not E. coli. We propose that CpIMPDH-targeted inhibitors can be developed into a new class of antibiotics that will spare some commensal bacteria. 相似文献
48.
Miller TS Ebejer N Güell AG Macpherson JV Unwin PR 《Chemical communications (Cambridge, England)》2012,48(60):7435-7437
The electrochemical properties of the closed ends and sidewalls of pristine carbon nanotube forests are investigated directly using a nanopipet electrochemical cell. Both are shown to promote fast electron transfer, without any activation or processing of the carbon nanotube material required, in contrast to the current model in the literature. 相似文献
49.
50.
It is shown that if (M, <, ?) is an o-minimal structure such that (M, <) is a dense total order and ? is a parameter-definable partial order on M, then ? has an extension to a definable total order. 相似文献