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排序方式: 共有243条查询结果,搜索用时 351 毫秒
51.
Bodnar WM Blackburn RK Krise JM Moseley MA 《Journal of the American Society for Mass Spectrometry》2003,14(9):971-979
The goal of this work was to evaluate the improvement in proteome coverage of complex protein mixtures gained by analyzing samples using both LC/ESI/MS/MS and LC/MALDI/MS/MS. Parallel analyses of a single sample were accomplished by interfacing a Probot fractionation system with a nanoscale LC system. The Probot was configured to perform a post-column split such that a fraction (20%) of the column effluent was sent for on-line LC/ESI/MS/MS data acquisition, and the majority of the sample (80%) was mixed with a matrix solution and deposited onto the MALDI target plate. The split-flow approach takes advantage of the concentration sensitive nature of ESI and provides sufficient quantity of sample for MALDI/MS/MS. Hybrid quadrupole time-of-flight mass spectrometers were used to acquire LC/ESI/MS/MS data and LC/MALDI/MS/MS data from a tryptic digest of a preparation of mammalian mitochondrial ribosomes. The mass spectrometers were configured to operate in a data dependent acquisition mode in which precursor ions observed in MS survey scans are automatically selected for interrogation by MS/MS. This type of acquisition scheme maximizes the number of peptide fragmentation spectra obtained and is commonly referred to as shotgun analysis. While a significant degree of overlap (63%) was observed between the proteins identified in the LC/ESI/MS/MS and LC/MALDI/MS/MS data sets, both unique peptides and unique proteins were observed by each method. These results demonstrate that improved proteome coverage can be obtained using a combination of these ionization techniques. 相似文献
52.
Efficient pricing of commodity options with early-exercise under the Ornstein-Uhlenbeck process 总被引:1,自引:0,他引:1
We analyze the efficiency properties of a numerical pricing method based on Fourier-cosine expansions for early-exercise options. We focus on variants of Schwartz? model based on a mean reverting Ornstein-Uhlenbeck process, which is commonly used for modeling commodity prices. This process however does not possess favorable properties for the option pricing method of interest. We therefore propose an approximation of its characteristic function, so that the Fast Fourier Transform can be applied for highest efficiency. 相似文献
53.
Dr. Giulia Neri Dr. Giuliana Mion Dr. Andrea Pizzi Dr. Wanda Celentano Dr. Linda Chaabane Prof. Michele R. Chierotti Prof. Roberto Gobetto Dr. Min Li Prof. Piergiorgio Messa Dr. Floryan De Campo Prof. Francesco Cellesi Prof. Pierangelo Metrangolo Prof. Francesca Baldelli Bombelli 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(44):10057-10063
In the continuous search for multimodal systems with combined diagnostic and therapeutic functions, several efforts have been made to develop multifunctional drug delivery systems. In this work, through a covalent approach, a new class of fluorinated poly(lactic-co-glycolic acid) co-polymers (F-PLGA) were designed that contain an increasing number of magnetically equivalent fluorine atoms. In particular, two novel compounds, F3-PLGA and F9-PLGA, were synthesized and their chemical structure and thermal stability were analyzed by solution NMR, DSC, and TGA. The obtained F-PLGA compounds were proven to form in aqueous solution colloidal stable nanoparticles (NPs) displaying a strong 19F NMR signal. The fluorinated NPs also showed an enhanced ability to load hydrophobic drugs containing fluorine atoms compared to analogous pristine PLGA NPs. Preliminary in vitro studies showed high cell viability and the NP ability to intracellularly deliver and release a functioning drug. 相似文献
54.
Tomasz Wojciechowski Zbigniew Ochal Paweł Socha Łukasz Dobrzycki Wanda Ziemkowska 《应用有机金属化学》2020,34(12):e5961
t-Butyl derivatives play a significant role in the organometallic chemistry of group 13 metals. It was shown on the basis of reactions of t-Bu3Al·OEt2 with [p-RC6H4S(O)2C(H)2C(Ph) = O] (where R = CH3, Cl) β-keto sulfones that the structure of the reaction products depends on the purity of the aluminum compound used. In the reactions, in addition to the expected complexes [p-RC6H4S(O2)C(H) = C (Ph)-OAl(t-Bu)2] [where R = CH3 ( 2 ); R = Cl ( 4 )] possessing β-keto sulfone ligands, complexes with β-hydroxy sulfone ligands [p-RC6H4S(O2)C(H)2-C (Ph)-OAl(t-Bu)2] [where R = CH3 ( 1 ); R = Cl ( 3 )] were formed. Compounds 1 and 3 were the result of the hydroalumination reaction of the β-keto sulfone ligands with t-Bu2AlH, which is an impurity of t-Bu3Al. These compounds are obtained, for the first time, as intermediate products in the hydrogenation reaction of β-keto sulfones. In this work, during t-Bu3Al·OEt2 production t-Bu2AlH·OEt2 formed as a by-product. Re-examination of reaction conditions of AlCl3 with t-BuMgCl resulted in a control of the t-Bu2AlH·OEt2 by-product content in t-Bu3Al·OEt2. 相似文献
55.
Antonio C. Fabretti Giancarlo Franchini Wanda Malavasi Giorgio Peyronel 《Polyhedron》1985,4(6):989-992
Some palladium(II) halide complexes with 2,5-dimethyl- (DTZ), 2-amino- (ATZ), 2-amino-5-methyl- (MATZ), 2-ethylamino- (EATZ) and 2-mercapto-5-methyl-1,3,4-thiadiazole (MTTZ) have been prepared and studied: PdX2 · 2L (L = DTZ, ATZ, MATZ : X = Cl, Br, I; L = EATZ: X = Br, I; L = MTTZ: X = I), PdCl2 · 2.5EATZ, PdCl2 · 3MTTZ, PdBr2 · 1.5MTTZ and PdX2 · L (L = DTZ, ATZ, MATZ, EATZ: X = Cl, Br; L = MTTZ: X = Cl(H2O), Br). In the PdX2 · 2L, PdCl2 · 2.5EATZ and PdCl2 · 3MTTZ complexes the palladium ions are cis-(2X, 2L)-coordinated, the coordination sites being Nring for DTZ, NR2 for ATZ, MATZ, EATZ and C = S for MTTZ. PdBr2 · 1.5MTTZ may be formulated as cis[PdBr2-2L] · [PdBr2 · L]. In the PdX2 · L complexes the ligand very likely acts as bidentate by using a ring-nitrogen atom as the second coordination site. 相似文献
56.
The dependence of the electron charge distribution in alkali halides on the lattice constant is examined. It is found that in the case of NaCl the non-rigid behavior of the electron charge density calculated from first principles can be well understood if one starts from the free-ion functions and takes into account the mutual overlap between them. The relevance of our results for the structural properties of alkali halides is pointed out in connection with recent ab-initio calculations. 相似文献
57.
Wanda?M.?Aylward Peter?G.?PickupEmail author 《Journal of Solid State Electrochemistry》2004,8(10):742-747
Sulfonated ormosil hydrogels (~80% water) were prepared using tetramethyl orthosilicate as a silica precursor and 2(4-chlorosulfonylphenyl)ethyltrichlorosilane to provide sulfonate functionality for ion-exchange and ion conductivity. Ruthenium(III) hexamine was used as a redox probe in electrochemical studies performed on porous carbon fibre paper electrodes impregnated with the gel. The gel-modified electrodes extracted Ru(NH3)63+ from solutions in 0.1 M CF3CO2Na(aq) with a partition coefficient of ~36, and with ~100% of the sulfonate sites being accessible for ion exchange. The Ru(NH3)63+/2+ couple exhibited reversible and facile electrochemistry in the gel, with a Ru(NH3)62+ diffusion coefficient of 4.9×10–8 cm2 s–1 determined by chronoamperometry. This is an order of magnitude higher than the mobility of this complex in Nafion. The hydrogel-modified electrodes were stable for days, and could be repeatedly loaded with Ru(NH3)63+.Special Issue to celebrate the 70th birthday of Professor Zbigniew Galus 相似文献
58.
Zurowska B Mroziński J Julve M Lloret F Maslejova A Sawka-Dobrowolska W 《Inorganic chemistry》2002,41(7):1771-1777
Thiocyanatonickel(II) and thiocyanatocobalt(II) complexes of the composition Ni(NCS)(2)(HIm)(2) (1) and Co(NCS)(2)(HIm)(2) (2), where HIm = imidazole, were prepared and studied. In particular, the crystal structure of Ni(NCS)(2)(HIm)(2) was determined by X-ray methods. This compound crystallizes in the monoclinic system, space group P2(1)/n, with a = 7.720(1) A, b = 5.557(1) A, c = 13.774(3) A, beta = 102.54(3) degrees, and Z = 2. Its structure consists of a one-dimensional polymeric chain in which nickel(II) ions are bridged by two thiocyanate groups bonding in an end-to-end fashion in a trans arrangement. The Ni...Ni distance is 5.557(1) A. The crystal packing is determined by the intermolecular hydrogen bonds and ring-stacking interactions. From their X-ray powder-diffraction patterns and IR spectra, the complexes 1 and 2 were found to be mutually isomorphous. The coordination compounds were identified and characterized using elemental analysis, magnetic measurements, and infrared and ligand-field spectra. Both complexes are first examples of ferromagnetically coupled one-dimensional polymeric compounds with double end-to-end thiocyanate bridges. The magnetic properties of the title compounds were investigated over the 1.9-290 K temperature range. The compounds exhibit long-range magnetic ordering with T(c) equal to 5.0 and 5.5 K for 1 and 2, respectively. Their isothermal magnetization was also studied. The magnetostructural properties of the nickel(II) compound obtained are discussed and compared to those of other double end-to-end thiocyanate-bridged nickel(II) complexes. 相似文献
59.
Summary The 1,3-dipolar cycloaddition reactions of 4,6-diazaphenanthrene 6-phenacylide formed in situ from the appropriate quaternary bromide in basic medium were investigated; as dipolarophiles acrylonitrile, ethyl acrylate,n-butyl acrylate and diethyl maleate were used.
1,3-Dipolare Cycloadditionsreaktionen von 4,6-Diazaphenanthren-6-phenacylid
Zusammenfassung Es wurden die 1,3-dipolaren Cycloadditionen von 4,6-Diazaphenanthren-6-phenacylid untersucht, welches in situ aus dem entsprechenden quaternären Bromid in Gegenwart von Alkali dargestellt wurde. Als Dipolarophile wurden Acrylnitril, Ethylacrylat,n-Buthylacrylat und Diethylmaleat eingesetzt.相似文献
60.