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1.
Heavy ion irradiation in the electronic stopping power region induces macroscopic dimensional change in metallic glasses and introduces magnetic anisotropy in some magnetic materials. The present work is on the irradiation study of ferromagnetic metallic glasses, where both dimensional change and modification of magnetic anisotropy are expected. Magnetic anisotropy was measured using Mössbauer spectroscopy of virgin and irradiated Fe40Ni40B20 and Fe40Ni38Mo4B18 metallic glass ribbons. 90 MeV 127I beam was used for the irradiations. Irradiation doses were 5×1013 and 7.5×1013 ions/cm2. The relative intensity ratios D 23 of the second and third lines of the Mössbauer spectra were measured to determine the magnetic anisotropy. The virgin samples of both the materials display in-plane magnetic anisotropy, i.e., the spins are oriented parallel to the ribbon plane. Irradiation is found to cause reduction in magnetic anisotropy. Near-complete randomization of magnetic moments is observed at high irradiation doses. Correlation is found between the residual stresses introduced by ion irradiation and the change in magnetic anisotropy. 相似文献
2.
Lisa M. Jones Hao Zhang Weidong Cui Sandeep Kumar Justin B. Sperry James A. Carroll Michael L. Gross 《Journal of the American Society for Mass Spectrometry》2013,24(6):835-845
As therapeutic monoclonal antibodies (mAbs) become a major focus in biotechnology and a source of the next-generation drugs, new analytical methods or combination methods are needed for monitoring changes in higher order structure and effects of post-translational modifications. The complexity of these molecules and their vulnerability to structural change provide a serious challenge. We describe here the use of complementary mass spectrometry methods that not only characterize mutant mAbs but also may provide a general framework for characterizing higher order structure of other protein therapeutics and biosimilars. To frame the challenge, we selected members of the IgG2 subclass that have distinct disulfide isomeric structures as a model to evaluate an overall approach that uses ion mobility, top-down MS sequencing, and protein footprinting in the form of fast photochemical oxidation of proteins (FPOP). These three methods are rapid, sensitive, respond to subtle changes in conformation of Cys?→?Ser mutants of an IgG2, each representing a single disulfide isoform, and may be used in series to probe higher order structure. The outcome suggests that this approach of using various methods in combination can assist the development and quality control of protein therapeutics. 相似文献
3.
Phenolic compounds extracted from extra virgin olive oil have attracted considerable recent attention. One of the components, (-)-oleocanthal (1), an inhibitor of the COX-1 and COX-2 enzymes, possesses similar potency as the NSAID ibuprofen. In this, a full account, we disclose the first- and now second-generation syntheses of both enantiomers of the oleocanthals, as well as the first synthesis of the closely related (-)-deacetoxy-oleuropein aglycone and a series of related analogues for structure activity studies. To demonstrate the utility of the second-generation synthesis, multigram quantities of (-)-oleocanthal were prepared in 10 steps (14% overall yield) from commercially available D-lyxose. 相似文献
4.
A series of triazole analogues of the nanaomycin family of antibiotics have been prepared using a ‘click’ dipolar cycloaddition of a naphthalene azide to various alkynes, followed by oxidation to the desired pyranonaphthoquinones. 相似文献
5.
W.C. Sperry G.A. Beer M.S. Dixit S.K. Kim J.A. MacDonald G.R. Mason A. Olin R.M. Pearce C. Sabev C. Wiegand 《Physics letters. [Part B]》1979,86(1):29-30
The intensity per stopped π?of|Δn|=2 pionic X-rays are observed to have larger variations with atomic number Z than do the |Δn|=1. The 6–4 intensity has a well-defined maximum at Z=34 with a FWHM of ΔZ ~10. 相似文献
6.
In subnormal glow discharge under d.c. excitation at different pressure in a varying transverse magnetic field (0 to 30 G)
some measurements have been carried out for various initial average tube currents. The voltage across the discharge increases
and average tube current and residual current decreases in the magnetic field. With the help of Beckman’s expression [4] for
the axial field and the electron density distribution in a transverse magnetic field the observed variation of current and
voltage can be satisfactorily explained. The variation of axial electric field with transverse magnetic field can be represented
to a fair degree of accuracy by the derived equation. The behaviour of residual current with magnetic field has been observed
in these oscillations. 相似文献
7.
An electrochemical furan annulation strategy has been developed for the synthesis of seven-membered rings. Key to the success of the annulation is the placement of a gem-dialkyl group in the tether. Voltammetric studies indicate that this effect lowers the oxidation potential by approximately 110 mV. 相似文献
8.
9.
In a quest to develop an effective, scalable synthesis of (+)-spongistatin 1 ( 1), we devised a concise, third-generation scalable synthesis of (+)- 7, the requisite F-ring tetrahydropyran aldehyde, employing a proline-catalyzed cross-aldol reaction. Subsequent elaboration to (+)-EF Wittig salt (+)- 3, followed by union with advanced ABCD aldehyde (-)- 4, macrolactonization and global deprotection permitted access to >1.0 g of totally synthetic (+)-spongistatin 1 ( 1). 相似文献
10.
Sperry JB Wilcox JM Gross ML 《Journal of the American Society for Mass Spectrometry》2008,19(6):887-890
The use of mass spectrometry to study protein-ligand interactions is expanding into more complex systems including protein-DNA interactions. The excess amount of a model DNA or, more typically, an oligodeoxynucleotide (ODN), needed to study such interactions in an amide hydrogen-deuterium (H/D) exchange experiment, for example, causes serious signal suppression in the protein analysis. We describe here a modification of the traditional H/D exchange protocol whereby we utilize a strong anion exchange column to rapidly remove the ODN from solution before MS analysis. We showed the successful incorporation of such a column in a study of two protein-ODN systems: (1) the DNA-binding domain of human telomeric repeat binding factor 2 with a telomeric oligodeoxynucleotide and (2) thrombin with the thrombin-binding aptamer. The approach gave no appreciable difference in back-exchange compared to a method in which no strong anion exchange (SAX) is used. 相似文献