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排序方式: 共有124条查询结果,搜索用时 15 毫秒
41.
Tadashi Yamaguchi Fumie Yamazaki Tasuku Ito 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(4):m213-m214
(1,4,7‐Trithiacyclononane)silver trifluoromethanesulfonate crystallizes in a tetrameric form from nitromethane, to give the title compound, [Ag4(C6H12S3)4](CF3SO3)4·2CH3NO2. The complex cation consists of four [AgL]+ units (L is 1,4,7‐trithiacyclononane), with four Ag—S—Ag bridges forming a cyclic tetramer. The almost planar Ag4S4 ring takes an octagonal form. 相似文献
42.
Urano Y Kamiya M Kanda K Ueno T Hirose K Nagano T 《Journal of the American Chemical Society》2005,127(13):4888-4894
Fluorescence imaging is the most powerful technique currently available for continuous observation of dynamic intracellular processes in living cells. Suitable fluorescence probes are naturally of critical importance for fluorescence imaging, but only a very limited range of biomolecules can currently be visualized because of the lack of flexible design strategies for fluorescence probes. At present, design is largely empirical. Here we show that the carboxylic group of traditional fluorescein dyes, formerly considered indispensable, has been replaced with other substituents, affording various kinds of new fluoresceins. Further, by breaking out of the traditional structure of fluorescein, we developed the first and totally rational design strategy for novel fluorescence probes based on a strict photochemical basis. The value of this approach is exemplified by its application to develop a novel, highly sensitive, and membrane-permeable fluorescence probe for beta-galactosidase, which is the most widely used reporter enzyme. 相似文献
43.
44.
Konno T Haneishi K Hirotsu M Yamaguchi T Ito T Yoshimura T 《Journal of the American Chemical Society》2003,125(31):9244-9245
Treatment of fac(S)-[Rh(aet)3] (aet = 2-aminoethanethiolate) with aqueous HBF4 in air led to the protonation at coordinated thiolato groups to give a rhodium(III) dimer, [{Rh(aet)2(Haet)}{Rh(aet)(Haet)2}](BF4)3 ([1](BF4)3). On the other hand, similar treatment of fac(Se)-[Rh(aes)3] (aes = 2-aminoethaneselenolate) produced a dinuclear rhodium(III) complex, [Rh2(selenocystamine)3](BF4)6 ([2](BF4)6), because of the autoxidation of coordinated selenolato groups by air. The crystal structures of [1](BF4)3, DeltaDelta-[1](BF4)3, and [2](BF4)6 were determined by X-ray crystallography. In [1]3+ two RhIII octahedrons are connected through a strong triple thiol-thiolate S-H...S hydrogen bond, while two RhIII octahedrons are directly joined by a triple diselenide bond in [2]6+. The cyclic voltammetry indicated that in acidic media the RhIII center in fac(Se)-[Rh(aes)3] is more easily oxidized to RhIV than that in fac(S)-[Rh(aet)3], which is responsible for the formation of coordinated diselenide bonds. 相似文献
45.
46.
Sakai K Ishigami E Konno Y Kajiwara T Ito T 《Journal of the American Chemical Society》2002,124(41):12088-12089
The first/second examples of partially oxidized 1-D platinum chain compounds consisting of cationic dimer units have been obtained from electro-oxidation of an aqueous solution containing cis-[Pt(NH3)2(OH2)2]2+ and acetate/propionate. The analytical and crystallographic studies reveal the mixed-valency of Pt(2.2+)infinity. The XPS confirms the presence of both Pt(II) and Pt(III). The solid-state physical measurements reveal that they are diamagnetic semiconductors and display a fairly broad, low-energy absorption band in the range of 500-3200 nm. 相似文献
47.
Sasakura K Hanaoka K Shibuya N Mikami Y Kimura Y Komatsu T Ueno T Terai T Kimura H Nagano T 《Journal of the American Chemical Society》2011,133(45):18003-18005
Hydrogen sulfide (H(2)S) has recently been identified as a biological response modifier. Here, we report the design and synthesis of a novel fluorescence probe for H(2)S, HSip-1, utilizing azamacrocyclic copper(II) ion complex chemistry to control the fluorescence. HSip-1 showed high selectivity and high sensitivity for H(2)S, and its potential for biological applications was confirmed by employing it for fluorescence imaging of H(2)S in live cells. 相似文献
48.
Koichi Inoue Nuntawat Prayoonhan Haruhito Tsutsui Tasuku Sakamoto Maiko Nishimura Toshimasa Toyo'oka 《Journal of separation science》2013,36(8):1356-1361
Dichlorprop is available for agricultural use as a chiral pesticide. In this study, the stereoselective determination of dichlorprop enantiomers in tea samples such as green, black, jasmine, and oolong was developed by ultra performance LC with fluorescence spectrometry after covalent chiral derivatization. The separation was achieved on an Acquity BEH C18 column with the mobile phase consisting of 0.1% formic acid in acetonitrile/water at a flow rate of 0.4 mL/min. In the covalent chiral derivatization using (S)‐(+)‐4‐(N,N‐dimethylaminosulfonyl)‐7‐(3‐aminopyrrolidin‐1‐yl)‐2,1,3‐benzoxadiazole, the peak resolution between the S and R‐dichlorprop enantiomers was 2.6. LODs and LOQs values were 10 and 50 ng/mL standard solution. The linearity of the calibration curves yielded the coefficients (r2 > 0.99, ranging from 0.05 to 5 μg/mL) of determination of each of the dichlorprop enantiomers. SPE extraction was used for the sample preparation of dichlorprop in various tea samples. Recoveries were in the range of 82.4–97.6% with associated precision values (within‐day: 82.4–95.8%, n = 6, and between‐day: 83.7–97.6% for 3 days) for repeatability and reproducibility. Based on this result, our method has been proven to be highly efficient and suitable for the routine assay of dichlorprop enantiomers in various tea samples. We propose that the ultra performance LC assay after covalent chiral derivatization would be the renewed tools in the era of chiral stationary platform for chiral pesticide residues in foods. 相似文献
49.
Coprecipitation with gallium hydroxide is studied for the preconcentration of trace metals in sea water before multi-element analysis by inductively-coupled plasma/atomic emission spectrometry. Gallium precipitates at pH 9 only when magnesium is present. Optimum conditions are established for multi-element preconcentration and removal of matrix elements. The method is almost free from contamination because of the use of highly pure gallium meetal and only a small amount of sodium hydroxide for pH adjustment. Spectral interferences from gallium are negligible and a concentratioin factor of more than 200 can be obtained. Detection limits range from a few ng l?1 to 150 ng l? for Al, Co, Cr, Fe, La, Mn, Ni, Ti, V, Zn, Y and Pb. Artificial and natural sea-water samples can be analyzed with adequate precision. 相似文献
50.
In this paper, simple and consistent open boundary conditions are presented for the numerical simulation of viscous incompressible laminar flows. The present approach is based on an arbitrary Lagrangian-Eulerian particle method using upwind interpolation. Three kinds of inlet/outlet boundary conditions are proposed for particle methods, a pressure specified inlet/outlet condition, a velocity profile specified inlet/outlet condition, and a fully developed flow outlet condition. These inlet/outlet conditions are realized by using boundary particles and modification to the physical value such as velocity. Poiseuille flows, flows over a backward-facing step, and flows in a T-shape branch are calculated. The results are compared with those of mesh-based methods such as the finite volume method. The method presented herein exhibits accuracy and numerical stability. 相似文献