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21.
Tam T. T. N. Nguyen Jesper Østergaard Stefan Stürup Bente Gammelgaard 《Analytical and bioanalytical chemistry》2013,405(6):1845-1854
A capillary electrophoresis inductively coupled plasma mass spectrometry method for separation of free cisplatin from liposome-encapsulated cisplatin and protein-bound cisplatin was developed. A liposomal formulation of cisplatin based on PEGylated liposomes was used as model drug formulation. The effect of human plasma matrix on the analysis of liposome-encapsulated cisplatin and intact cisplatin was studied. The presence of 1 % of dextran and 4 mM of sodium dodecyl sulfate in HEPES buffer was demonstrated to be effective in improving the separation of liposomes and cisplatin bound to proteins in plasma. A detection limit of 41 ng/mL of platinum and a precision of 2.1 % (for 10 μg/mL of cisplatin standard) were obtained. Simultaneous measurements of phosphorous and platinum allows the simultaneous monitoring of the liposomes, liposome-encapsulated cisplatin, free cisplatin and cisplatin bound to plasma constituents in plasma samples. It was demonstrated that this approach is suitable for studies of the stability of liposome formulations as leakage of active drug from the liposomes and subsequent binding to biomolecules in plasma can be monitored. This methodology has not been reported before and will improve characterization of liposomal drugs during drug development and in studies on kinetics. Figure
A method for distinguishing free cisplatin from liposome-encapsulated and protein-bound platinum in human plasma allows for studies of stability and kinetics of new drug formulations during drug development 相似文献
22.
A carotenoic acid was used to obtain a long-chain unsaturated lysophosphocholine. The carotenoid lysophosphocholine was synthesized by two methods. The first method resulted in mixtures of regioisomers for each step in the synthetic route. Homo- and heteronuclear 1D and 2D NMR methods were employed to elucidate the structures of the individual isomers and their intermediates. The pure regioisomer [1-(beta-apo-8'-carotenoyl)-2-lyso-glycero-3-phosphocholine] was obtained by a second method, but in low yield. The 1D 1H NMR subtraction spectrum of the mixture and the pure regioisomer was used to interpret the 1H shifts of the unsaturated acyl moieties. The 1H and 13C signals of the acyl chain show characteristic shifts depending on the positions of the choline and the acyl group attached to the glycerol backbone. Therefore, the unsaturated acyl chain signals have diagnostic values for the identification of isomers of unsaturated (lyso)phosphocholines. Chemical shifts and indirect coupling constants are reported for each of the major components of the mixtures. The methods used were 1D (1H, 13C and 31P) and 2D (H,H-COSY, HMBC, HSQC and HETCOR) NMR. 相似文献
23.
Gustav J. Wrmer Bente K. Hansen Johan Palmfeldt Thomas B. Poulsen 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(34):12044-12048
Cyclopropenes are an important new addition to the portfolio of functional groups that can be used for bioorthogonal couplings. The inert nature of these highly strained compounds in complex biological systems is almost counterintuitive given their established electrophilic properties in organic synthesis. Here we provide the first demonstration of a cyclopropene that is capable of direct conjugation to protein targets in cells and show that this compound preferentially alkylates the active site cysteine of glutathione S‐transferase omega‐1 (GSTO1). 相似文献
24.
E. A. J. M. Bente W. Hogervorst 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1989,14(2):119-128
The 5dnd and 5dng J=2, 3 and 4 as well as the 5dns J=2 autoionising series of barium have been studied with two-step pulsed laser excitations in an atomic beam. Dipole moments and the interactions with the 6s∈l continua were fitted starting from existing Multi-channel Quantum Defect Theory (MQDT) analyses. The interactions of the 5dnd J=4 and 2, and 5dns J=2 series with 6sεg J=4 and 6sεd J=2 continua could be analysed succesfully. 相似文献
25.
A basic bismuth(III) nitrate with the composition [Bi(6)O(4)(OH)(4)](0.5)[Bi(6)O(5)(OH)(3)](0.5)(NO(3))(5.5) formed in a slow crystal growth mode has an ordered crystal structure with the monoclinic space group P2(1) and lattice parameters a = 15.850(3), b = 14.986(3), c = 18.230(4) ?, β = 107.329(17)° and volume V = 4133.6 ?(3) (Henry et al. 2003). In a very fast crystal growth mode the complex ions disorder in another P2(1) cell with slightly different lattice parameters a = 15.8404(1), b = 15.1982(1), c = 18.3122(1) ?, β = 106.829(1)° and V = 4219.8 ?(3). This cell can be related to two smaller cells: a monoclinic C2/m cell with a = 13.7161(1), b = 15.1943(1), c = 10.2399(1) ?, β = 98.586(1)° and V = 2110.1 ?(3) and a trigonal R3 cell with a = 15.18650(6), c = 15.8416(1) ? (hexagonal setting) and V = 3164.1 ?(3). These smaller cells correspond to average structures and hence the X-ray data do not account for the difference in the structures of the two different complex ions. However, when analysing neutron powder diffraction data, it is possible to distinguish between the two complex ions using a trigonal R3 cell with a = 15.1865(1) and c = 15.8416(1) ? (hexagonal setting). In a Rietveld type structure model refinement with a total of 28 atom sites (4 Bi, 3 N, 15 O and 6 H), the composition of this sample is determined to be [Bi(6)O(4)(OH)(4)](0.54(1))[Bi(6)O(5)(OH)(3)](0.46(1))(NO(3))(5.54(1)). 相似文献
26.
27.
Springborg J Nielsen B Olsen CE Søtofte I 《Journal of the American Chemical Society》2002,124(18):5084-5090
The reaction of the inside protonated form of the tricyclic amine 1,4,8,12-tetraazatricyclo[6.6.3.2(4,12)]nonadecane (1) with iron(III) affords the inside monoprotonated form of the corresponding imine 4,8,12-triaza-1-azoniatricyclo[6.6.3.2(4,12)]nonadec-1(15)-ene (2), which was isolated as the tetrabromozincate salt (2a) in a yield of 78%. The crystal structure of 2a has been solved by X-ray diffraction at T = 120 K. In the imine cation the acidic hydrogen atom and the lone pairs of the nitrogen atoms are oriented toward the inside of the cavity. The acidic hydrogen atom is bound to a nitrogen atom belonging to the triazacyclononane entity. The imine double bond is situated between the N-atom of the triazacyclononane entity and the C-atom belonging to one of the three trimethylene bridges. The imine 2 is stable in acidic solution and the inside coordinated proton is very robust in acidic solution. In basic solution the imine reacts fast to give a quantitative formation of the inside protonated form of the hemiaminal 1,4,8,12-tetraazatricyclo[6.6.3.2(4,12)]nonadecan-5-ol (3). The equilibrium constant K(im) = [3][H(+)]/[2] was determined at three different temperatures from potentiometric measurements, which gave K(im) = 1.57(1) x 10(-5) M at 25 degrees C, Delta S degrees = -83(1) J mol(-1) K(-)(1),and Delta H degrees = 2.6(3) kJ mol(-1) at I = 1.0 M (NaCl). The inside coordinated proton in 3 is labile in basic solution and the rate for NH/ND exchange was determined by (1)H NMR at three different temperatures. The reaction followed the expression k(obs) = k(ex)[OD(-)] with k(ex) = 0.0978(30) dm(3) mol(-1) s(-1) at 25 degrees C, Delta S(++) = 87(4) J mol(-1) K(-1), and Delta H(++) = 104.9(11) kJ mol(-1) at I = 1.0 M (NaCl). The exchange rate is more than 5 x 10(6) times faster than that of the parent saturated cage 1. This extreme enhancement of reactivity is explained by an intramolecular proton transfer reaction mediated by hydroxy and oxy groups flipping in and out of the cavity, which mechanistically has resemblance to the transport of ions in a biological system. 相似文献
28.
Catalytic Asymmetric [4+2]‐Cycloadditions Using Tropolones: Developments,Scope, Transformations,and Bioactivity 下载免费PDF全文
Niels Hammer Dr. Jeremy D. Erickson Dr. Vibeke H. Lauridsen Joakim B. Jakobsen Bente K. Hansen Kristian M. Jacobsen Prof. Dr. Thomas B. Poulsen Prof. Dr. Karl Anker Jørgensen 《Angewandte Chemie (International ed. in English)》2018,57(40):13216-13220
An organocatalyzed asymmetric [4+2]‐cycloaddition between tropolones and electron‐deficient dienophiles is presented. Complex and biologically interesting dihydrohomobarrelenone scaffolds are formed through a Diels–Alder reaction utilizing bifunctional Brønsted‐base catalysis, affording the corresponding bridged bicyclic cycloadducts in up to quantitative yields with good enantio‐ (up to 92 % ee) and diastereoselectivity (up to >20:1 d.r.). The synthetic value of the obtained products is explored by downstream transformations, including photoisomerizations, and their biological relevancy by in vivo testing in MCF‐7 cancer cells. 相似文献
29.
D. J. McAdoo P. F. Bente M. L. Gross F. W. McLafferty 《Journal of mass spectrometry : JMS》1974,9(5):525-535
Major factors which determine the distribution of internal energy of a primary product ion A+, P(E)A+, at formation are delineated in terms of the quasi-equilibrium theory and a variety of experimental evidence is offered to support these conclusions. These major factors include: the P(E) of the molecular ion, the rate constants as a function of energy, κ(E), for M+·→A+ + N0 and for competing reactions of M+·, and the partitioning of excess internal energy between A+ and N0. The ‘fluctuation effect’ on this partitioning makes P(E)A+ relatively insensitive to many structural and energy changes. 相似文献
30.
Gammelgaard B Gabel-Jensen C Stürup S Hansen HR 《Analytical and bioanalytical chemistry》2008,390(7):1691-1706
The aim of this paper is to give an overview of analytical data on the identification of selenium compounds in biological
samples with relevance for selenium metabolism. Only studies applying the combination of element-specific inductively coupled
plasma mass spectrometry as well as molecular electrospray mass spectrometry detection have been included. Hence, selenium
compounds are only considered identified if molecular mass spectra obtained by analysis of the authentic biological sample
have been provided. Selenium compounds identified in selenium-accumulating plants and yeast are included, as extracts from
such plants and yeast have been widely used for examination of the cancer-preventive effect of selenium in cell lines, animal
models and human intervention trials. Hence, these selenium compounds are available for absorption and further metabolism.
Identification of selenium metabolites in simulated gastric and intestinal juice, intestinal epithelial tissue, liver and
urine is described. Hence, selenium metabolites identified in relation to absorption, metabolism and excretion are included. 相似文献