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51.
Poster DL Kucklick JR Schantz MM Porter BJ Leigh SD Wise SA 《Analytical and bioanalytical chemistry》2003,375(2):223-241
The concentrations of a wide range of polychlorinated biphenyl congeners (PCBs) and chlorinated pesticides in a fish tissue Standard Reference Material (SRM) have been determined using multiple methods of analysis. This material, SRM 1946, Lake Superior Fish Tissue, was recently issued by the National Institute of Standards and Technology (NIST) and complements a suite of marine environmental natural-matrix SRMs that are currently available from NIST for the determination of organic contaminants such as aliphatic hydrocarbons, polycyclic aromatic hydrocarbons (PAHs), PCBs, and chlorinated pesticides. SRM 1946 is a fresh tissue homogenate (frozen) prepared from filleted adult lake trout (Salvelinus namaycush namaycush) collected from the Apostle Islands region of Lake Superior. SRM 1946 has certified and reference concentrations for PCB congeners, including the three non- ortho PCB congeners, and chlorinated pesticides. Certified concentrations are available for 30 PCB congeners and 15 chlorinated pesticides. Reference concentrations are available for 12 PCB congeners and 2 chlorinated pesticides. In addition, SRM 1946 is characterized for additional chemical constituents and properties: fatty acids, extractable fat, methylmercury, total mercury, selected trace elements, proximates, and caloric content. The characterization of chlorinated compounds is described in this paper with an emphasis on the approach used for the certification of the concentrations of PCB congeners and chlorinated pesticides. The PCB congener and chlorinated pesticide data are also compared to concentrations in other marine natural-matrix reference materials available from NIST (fish oil, mussel tissue, whale blubber, and a second fresh frozen fish tissue homogenate prepared from filleted adult lake trout collected from Lake Michigan) and from other organizations such as the National Research Council Canada (ground whole carp), the International Atomic Energy Agency (fish homogenate), and the European Commission Joint Research Centre [fish oils (cod and mackerel) and mussel tissue]. 相似文献
52.
Fisher DM Fenton RR Aldrich-Wright JR 《Chemical communications (Cambridge, England)》2008,(43):5613-5615
An in vivo study for determining the toxicity and efficacy of [Pt(S,S-dach)(phen)Cl(2).1.5H(2)O.0.5HCl (PHENSS) in female Specific Pathogen Free (SPF) Swiss nude mice bearing PC3 tumour xenografts revealed PHENSS to be non-toxic and effective in decreasing tumour growth. 相似文献
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3D bioprinting often involves human mesenchymal stem cells (hMSC) that are differentiated into the desired cells to replace body parts like ears. Scaffolds of crosslinked hydrogels offer structural support during differentiation. Different photoinitiators are used to make free radicals that photocrosslink these hydrogels; the more penetrating ultraviolet A1 (UVA1) (340–400 nm) wavelengths can be used because Irgacure 2959 only absorbs in the UV (100–400 nm) region. We questioned if the L929 mouse fibroblast cells used in the American Society for Testing Materials standard cytotoxicity assays (F895&F813) can predict the viability of hMSC after exposure to UVA1 radiation alone and in combination with Irgacure 2959 (0.05–0.5% w/v usual range). We exposed both cell types to a high dose of LED UVA1 (370 ± 5 nm; 788 kJ m?2) and side by side to increasing UVA1 doses from a glass‐filtered black light source combined with either 0.05% (w/v) or 0.5% (w/v) of Irgacure 2959 and monitored their viabilities using flow cytometry. We found UVA1 radiation alone killed ~50% of the hMSC cells compared to ~8% of the L929 cells and significantly more hMSC than L929 died after UVA1 with Irgacure 2959. Thus, L929 cannot be used to accurately predict the viability of hMSC after these specific 3D bioprinting conditions. 相似文献
56.
Tomáš Klejch Radek Pohl Zlatko Janeba Minghan Sun Dianne T. Keough Luke W. Guddat Dana Hocková 《Tetrahedron》2018,74(40):5886-5897
Hypoxanthine-guanine-xanthine phosphoribosyltransferase (HGXPRT) is a key enzyme of the purine salvage pathway and its activity is crucial for the survival of certain parasites e.g. Plasmodium falciparum (Pf). Acyclic nucleoside phosphonates (ANPs) containing either guanine or hypoxanthine as the purine base are inhibitors of this enzyme. In this part of a SAR study, these two naturally-occurring nucleobases attached to an acyclic moiety were replaced by allopurinol or favipiravir. Both allopurinol and favipiravir ANPs were prepared via Mitsunobu reaction. The alkylation of favipiravir was optimized to yield both N- and O- regioisomers but the N-regioisomers were unstable under deprotection conditions. Thus, only the ANPs containing the O-isomer of favipiravir and those containing allopurinol were evaluated as potential inhibitors of human HGPRT and PfHGXPRT. Two ANPs with allopurinol as the base have Ki values of 10?μM and 30?μM for PfHGXPRT but do not inhibit human HGPRT activity at concentrations of 100–150?μM. 相似文献
57.
Dianne R. Bond Luigi R. Nassimbeni Fumio Toda 《Journal of chemical crystallography》1989,19(5):847-859
The structures of the 12 molecular complexes oftrans-9,10-dihydroxy-9,10-diphenyl-9,10-dihydroanthracene with 4-methylcyclohexanone (1) and with 2-methylcyclohexanone (2) have been determined by X-ray crystallography. The crystal data are as follows: Compound (1):P22/c,a=8.838(2) Å,b=8.92(1) Å,c=20.879(8)=Å,=98.67(2)°,V=1627(2) Å3,Z=2 andR=0.062 for 2201 unique MoK reflections; Compound (2):P¯1,a=8.917(3) Å,b=9.900(2) Å,c=11.250(4) Å,a=68.72(2)°,=64.39(3)°, =74.86(2)°,V=828.1(5) Å3,Z=1 andR=0.098 for 2563 unique reflections. Both inclusion compounds exhibit O-HO=C hydrogen bonding interactions. The thermal properties of these compounds have been characterized by DTA and TGA thermograms. 相似文献
58.
Eric D. Bloch Wendy L. Queen Matthew R. Hudson Jarad A. Mason Dianne J. Xiao Leslie J. Murray Roxana Flacau Craig M. Brown Jeffrey R. Long 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2016,128(30):8747-8751
A chromium(II)‐based metal–organic framework Cr3[(Cr4Cl)3(BTT)8]2 (Cr‐BTT; BTT3−=1,3,5‐benzenetristetrazolate), featuring coordinatively unsaturated, redox‐active Cr2+ cation sites, was synthesized and investigated for potential applications in H2 storage and O2 production. Low‐pressure H2 adsorption and neutron powder diffraction experiments reveal moderately strong Cr–H2 interactions, in line with results from previously reported M‐BTT frameworks. Notably, gas adsorption measurements also reveal excellent O2/N2 selectivity with substantial O2 reversibility at room temperature, based on selective electron transfer to form CrIII superoxide moieties. Infrared spectroscopy and powder neutron diffraction experiments were used to confirm this mechanism of selective O2 binding. 相似文献
59.
The pentafluorooxotellurate compound ReO(2)(OTeF(5))(3) has been synthesized from the reaction of ReO(2)F(3) with B(OTeF(5))(3) and structurally characterized in solution by (19)F and (125)Te NMR spectroscopy and in the solid state by Raman spectroscopy. The NMR and vibrational spectroscopic findings are consistent with a trigonal bipyramidal arrangement in which the oxygen atoms and an OTeF(5) group occupy the equatorial plane. The (19)F and (125)Te NMR spectra show that the axial and equatorial OTeF(5) groups of ReO(2)(OTeF(5))(3) are fluxional and are consistent with intramolecular exchange by means of a pseudorotation. The Lewis acid behavior of ReO(2)(OTeF(5))(3) is demonstrated by reaction with OTeF(5)(-). The resulting cis-ReO(2)(OTeF(5))(4)(-) anion was characterized as the tetramethylammonium salt in solution by (19)F and (125)Te NMR spectroscopy and in the solid state by Raman spectroscopy and X-ray crystallography. The compound crystallizes in the triclinic system, space group P&onemacr;, with a = 13.175(7) ?, b = 13.811(5) ?, c = 15.38(1) ?, alpha = 72.36(5)(o), beta = 68.17(5)(o), gamma = 84.05(4)(o), V = 2476(2) ?(3), D(calc) = 3.345 g cm(-)(3), Z = 4, R = 0.0547. The coordination sphere about Re(VII) in cis-ReO(2)(OTeF(5))(4)(-) is a pseudooctahedron in which the Re-O double bond oxygens are cis to one another. 相似文献
60.
Ultraviolet radiation (UVR) exposure to internal tissues for diagnostic, therapeutic and cosmetic procedures has increased dramatically over the past decade. The greatest increase in UVR exposure of internal tissues occurs in the cosmetic industry where it is combined with oxidizing agents for teeth whitening, often in conjunction with indoor tanning. To address potential carcinogenic risks of these procedures, we analyzed the formation and repair of the DNA photoproducts associated with the signature mutations of UVR. Radioimmunoassay was used to quantify the induction and repair of cyclobutane pyrimidine dimers and pyrimidine(6-4)pyrimidone photoproducts in DNA purified from three reconstructed tissues, EpiDerm(TM) , EpiGingival(TM) and EpiOral(TM) . We observed comparable levels of DNA damage in all tissues immediately after UVR exposure. In contrast, repair was significantly reduced in both oral tissues compared with EpiDerm(TM) . Our data suggest that UVR exposure of oral tissues can result in accumulation of DNA damage and increase the risk for carcinoma and melanoma of the mouth. Because NER is a broad-spectrum defense against DNA damage caused by a variety of agents in addition to UVR, our data suggest that the relatively low NER efficiency observed in oral tissues may have wide-ranging consequences in this highly exposed environment. 相似文献