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81.
Gustavo Caetano-Anollés Brant J. Bassam 《Applied biochemistry and biotechnology》1993,42(2-3):189-200
DNA amplification fingerprinting (DAF) is a strategy for genetic typing and mapping that uses one or more very short (≥5 nt)
arbitrary oligonucleotides to direct the enzymatic amplification of discrete portions of a DNA template resulting in a spectrum
of products characteristic of the DNA starting material. Polymorphisms from simple banding patterns are useful as genetic
markers while more complex and informative patterns are suitable for DNA fingerprinting. The use of polyacrylamide gel electrophoresis
and silver staining can adequately resolve the spectrum of DAF products into detailed and reproducible patterns. 相似文献
82.
Use of Micellar-Enhanced Ultrafiltration at Low Surfactant Concentrations and with Anionic-Nonionic Surfactant Mixtures 总被引:1,自引:0,他引:1
Fillipi BR Brant LW Scamehorn JF Christian SD 《Journal of colloid and interface science》1999,213(1):68-80
Micellar-enhanced ultrafiltration is a separation technique which can be used to remove metal ions or dissolved organics from water. Metal ions bind to the surface of negatively charged micelles of an anionic surfactant while organic solutes tend to dissolve or solubilized within the micelles. The mixture is then forced through an ultrafiltration membrane with pore sizes small enough to block passage of the micelles and associated metal ions and/or dissolved organics. Monomeric or unassociated surfactant passes through the membrane and does not contribute to the separation. This paper considers advantages of addition of small concentrations of nonionic surfactant to an anionic surfactant; the resulting anionic-nonionic mixed micelles exhibit negative deviation from ideality of mixing which leads to a smaller fraction of the surfactant being present as monomer and a subsequently larger fraction present in the micellar form. The addition of nonionic surfactant improved the separation of divalent zinc substantially at total concentrations above the critical micelle concentration (cmc) of the anionic surfactant. Both zinc and tert-butylphenol (a nonionic organic solute) show unexpected rejection at surfactant concentrations moderately below the cmc, where micelles are absent. This is considered as due to a higher surfactant concentration in the gel layer adjacent to the membrane where micelles are present. Reduction of this rejection at lower transmembrane pressure drops supports this mechanism. Some rejection of zinc was observed in the absence of surfactant but not of tert-butylphenol, indicating an additional effect of membrane charge for ionic solutes. Copyright 1999 Academic Press. 相似文献
83.
Polyacetylene, (CH)x, has been doped with trimethyloxonium hexachloroantimonate, (CH3)3O+SbCl(1), in dichloromethane and acetonitrile. The maximally doped (CH)x films have moderate conductivities [σRT(CH2Cl2) = 10, σRT(CH3CN) = 0.7 Ω?1 cm?1]. Reactions between 1 and (CH)x CH2Cl2 or CH3CN were followed in situ by 1H nuclear magnetic resonance spectroscopy and x-band electron spin resonance spectroscopy. It was found that the reactions in the two solvents are different. In dichloromethane the dopant is SbCl5, which forms from the decomposition of 1, and doping proceeds by electron removal from (CH)x chains. Based on the ESR signal loss, an estimate can be made of the diffusion rate of SbCl5, into the (CH)x fibrils in CH2Cl2; it is found to be ca. 10?17 cm2/s. In acetonitrile the dopant appears to be either CH3CNCH, H+, CH, or a combination of one or more of these dopants. It is postulated that the CH3CNCH, CH, and/or H+ dopant covalently binds to the (CH)x chain. X-ray photoelectron spectra show that films doped with excess 1 in both solvents have approximately one SbCl per 33 CH units. 相似文献
84.
Fullerol cluster formation in aqueous solutions: implications for environmental release 总被引:4,自引:0,他引:4
Brant JA Labille J Robichaud CO Wiesner M 《Journal of colloid and interface science》2007,314(1):281-288
Here we report on the characteristics of fullerol in aqueous systems and examine those conditions that affect the physical state of fullerol in water. When dispersed in water fullerol forms polydisperse suspensions characterized by both small ( approximately 100 nm) and large associations (>500 nm). These clusters are charged with a point of zero net proton charge (PZNPC) of approximately pH 3. Though the size of fullerol clusters may be manipulated through changes in solution chemistry, principally pH, cluster formation cannot be entirely prevented through these means alone. The fullerol cluster structure is amorphous as revealed by X-ray diffraction analysis, which is in contrast to clusters of C(60) formed through dissolution in toluene and then introduced into water through sonication (SONnC(60)). The SONnC(60) clusters are crystalline with a structure similar to that of unreacted C(60) crystals. 相似文献
85.
Robert T. Stibrany Patrick Brant 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(5):644-645
In the title compound, [(CH3)2(C7H7)NH][(C6F5)3B(OH)] or C9H14N+·C18HBF15O?, the distorted tetrahedral borate anions are strongly hydrogen bonded to the substituted ammonium cations. The N?O separation in the N—H?O hydrogen bond is 2.728 (3) Å. 相似文献
86.
Characterizing the impact of preparation method on fullerene cluster structure and chemistry 总被引:2,自引:0,他引:2
Brant JA Labille J Bottero JY Wiesner MR 《Langmuir : the ACS journal of surfaces and colloids》2006,22(8):3878-3885
We examined the physical and chemical characteristics of colloidal dispersions of fullerene materials (nC60) produced through several solvent exchange processes and through extended mixing in water only. The nC60 produced via the different methods were unique from each other with respect to size, morphology, charge, and hydrophobicity. The greatest dissimilarities were observed between the nC60 produced by extended mixing in water alone and the nC60 produced by solvent exchange processes. The role of the respective solvents in determining the characteristics of the various nC60 were attributed to differences in the solvent-C60 interactions and the presence of the solvent as a residual in the nC60 structure, indicating the significance of the solvent properties in determining the ultimate characteristics of the colloidal fullerene. Thus, fullerene C60 that may become mobilized through natural processes (agitation in water) may behave in dramatically different ways than those produced through more artificial means. These results highlight the difficulties in generalizing nC60 properties, particularly as they vary in potential toxicity considerations. 相似文献
87.
Dr. Sabrina Heng Dr. Xiaozhou Zhang Dr. Jinxin Pei Dr. Alaknanda Adwal Dr. Philipp Reineck Prof. Brant C. Gibson Prof. Mark R. Hutchinson Prof. Andrew D. Abell 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(3):854-862
A new spiropyran-based stimuli-responsive delivery system is fabricated. It encapsulates and then releases an extraneous compound in response to elevated levels of Zn2+, a critical factor in cell apoptosis. A C12-alkyl substituent on the spiropyran promotes self-assembly into a micelle-like nanocarrier in aqueous media, with nanoprecipitation and encapsulation of added payload. Zn2+ binding occurs to an appended bis(2-pyridylmethyl)amine group at biologically relevant micromolar concentration. This leads to switching of the spiropyran (SP) isomer to the strongly fluorescent ring opened merocyanine-Zn2+ (MC-Zn2+) complex, with associated expansion of the nanocarriers to release the encapsulated payload. Payload release is demonstrated in solution and in HEK293 cells by encapsulation of a blue fluorophore, 7-hydroxycoumarin, and monitoring its release using fluorescence spectroscopy and microscopy. Furthermore, the use of the nanocarriers to deliver a caspase inhibitor, Azure B, into apoptotic cells in response to an elevated Zn2+ concentration is demonstrated. This then inhibits intracellular caspase activity, as evidenced by confocal microscopy and in real-time by time-lapsed microscopy. Finally, the nanocarriers are shown to release an encapsulated proteasome inhibitor ( 5 ) in Zn2+-treated breast carcinoma cell line models. This then inhibits intracellular proteasome and induces cytotoxicity to the carcinoma cells. 相似文献
88.
Prof. Ralf I. Kaiser Dr. Surajit Maity Dr. Brant M. Jones 《Angewandte Chemie (International ed. in English)》2015,54(1):195-200
Contemporary mechanisms for the spontaneous formation of glycerol have not been able to explain its existence on early Earth. The exogenous origin and delivery of organic molecules to early Earth presents an alternative route to their terrestrial in situ formation since biorelevant molecules like amino acids, carboxylic acids, and alkylphosphonic acids have been recovered from carbonaceous chondrites. Reported herein is the first in situ identification of glycerol, the key building block of all cellular membranes, formed by exposure of methanol‐based — interstellar model ices to ionizing radiation in the form of energetic electrons. These results provide compelling evidence that the radiation‐induced formation of glycerol in low‐temperature interstellar model ices is facile. Synthesized on interstellar grains and eventually incorporated into the “building material” of solar systems, biorelevant molecules such as glycerol could have been dispensed to habitable planets such as early Earth by comets and meteorites. 相似文献
89.
Alfred Basiner Carlotto von Rentelen Brant und Arthur Zander 《Fresenius' Journal of Analytical Chemistry》1882,21(1):617-621
Ohne Zusammenfassung 相似文献
90.
Martelli C Olivero P Canning J Groothoff N Gibson B Huntington S 《Optics letters》2007,32(11):1575-1577
A focused ion beam is used to mill side holes in air-silica structured fibers. By way of example, side holes are introduced in two types of air-structured fiber, (1) a photonic crystal four-ring fiber and (2) a six-hole single-ring step-index structured fiber. 相似文献