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221.
Empty fruit bunch (EFB), an underutilized waste product of oil palm processing, was studied as a substrate for the production of humic acids (HA) by a Trichoderma reesei strain by solid-state fermentation (SSF) in Raimbault columns. HA have attracted the attention of many investigators due to their applications in agriculture, industry, the environment, and biomedicine. Commercial HA are currently chemically extracted from peat and coal, which are nonrenewable carbon sources. Biotechnological processes are important for their sustainable and controlled production, with SSF being especially promising for mimicking the natural habitat of fungi. Trichoderma sporulation and HA production are related, and the results of this study showed that SSF stimulated fast sporulation. The productivity related to HA was much higher than that of the biomass, indicating an efficient utilization of EFB. These findings, added to the low cost of EFB, make SSF an attractive process for HA production. 相似文献
222.
223.
CO Hydrogenation on Cobalt‐Based Catalysts: Tin Poisoning Unravels CO in Hollow Sites as a Main Surface Intermediate
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Dr. Anaëlle Paredes‐Nunez Davide Lorito Dr. Laurence Burel Dr. Debora Motta‐Meira Dr. Giovanni Agostini Nolven Guilhaume Dr. Yves Schuurman Dr. Frederic Meunier 《Angewandte Chemie (International ed. in English)》2018,57(2):547-550
Site poisoning is a powerful method to unravel the nature of active sites or reaction intermediates. The nature of the intermediates involved in the hydrogenation of CO was unraveled by poisoning alumina‐supported cobalt catalysts with various concentrations of tin. The rate of formation of the main reaction products (methane and propylene) was found to be proportional to the concentration of multi‐bonded CO, likely located in hollow sites. The specific rate of decomposition of these species was sufficient to account for the formation of the main products. These hollow‐CO are proposed to be main reaction intermediates in the hydrogenation of CO under the reaction conditions used here, while linear CO are mostly spectators. 相似文献
224.
The effect of substituents on Si and N on t1/2 values in the addition of carbamoylsilanes to acrylonitrile was explored. After examination of steric and structural parameters, the best correlation was found to be that rates increased with a decrease in the ionization potential of the carbamoylsilane. 相似文献
225.
Garcia Nancy L. Motta Mariana R. 《Methodology and Computing in Applied Probability》2003,5(1):109-121
The objective of this work is to generate random samples of the unique stationary distribution associated to the stochastic model for grain storage in a finite bidimensional silo. The support of this measure is an unbounded and continuous state space and therefore a truncation was necessary to apply the CFTP perfect simulation scheme. The performance of the algorithm was measured by comparing the sample moments to the theoretical ones. 相似文献
226.
Dr. Wei Jiang Chengyi Xiao Linxiao Hao Prof. Zhaohui Wang Harald Ceymann Prof. Christoph Lambert Dr. Simone Di Motta Prof. Fabrizia Negri 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(22):6764-6775
The copper‐mediated Ullmann coupling of 1,7‐dibromoperylene bisimides afforded structurally perfect singly‐linked perylene bisimide (PBI) arrays, whilst the homo‐coupling of 1,12‐dibromoperylene bisimides gave doubly‐linked and triply‐linked diperylene bisimides. The interactions of three bay‐linked diperylene bisimides that differed in their linkage (singly, doubly, and triply) were investigated in their neutral and reduced forms (mono‐anion to tetra‐anion). UV/Vis absorption and fluorescence spectroscopy revealed different degrees of interaction, which was explained by exciton coupling and conjugation effects. The electrochemical properties and spectroelectrochemistry also showed quite‐different degrees of PBI interactions in the reduced mixed‐valence species, which was apparent by the observation of CT bands. The interpretation of the experimental findings was supported by spin‐restricted and ‐unrestricted DFT and time‐dependent TD‐DFT calculations with the long‐range‐corrected CAM‐B3LYP functional. Accordingly, the degree of interaction in both the neutral and reduced forms of the bay‐linked PBIs was qualitatively in the order doubly linked<singly linked?triply linked, owing to the different degrees of twisting and flexibility between the two PBIs moieties. Only triply linked diPBI showed completely delocalized wavefunctions over the entire π‐system. 相似文献
227.
Layane Lenardon Leonardo Zanchetti Meneghini Rodrigo Barcellos Hoff Tanara Magalhães Campos Motta Tânia Mara Pizzolato Marco Flôres Ferrão 《Analytical letters》2017,50(13):2068-2077
Milk adulteration is a concern in many countries, including Brazil. There are many compounds used as adulterants, including cheese whey, a by-product of cheese. Recently, we have developed a proteomic-like technique for separation and characterization of caseinomacropeptide using liquid chromatography coupled to mass spectrometry with electrospray ionization. Caseinomacropeptide is important because it can be used as marker when cheese whey adulteration is performed in bovine milk. Furthermore, it is difficult to establish reference values for caseinomacropeptide levels because of the variation of milk composition. The aim of this study was to verify the average value for caseinomacropeptide present in bovine raw milk collected by Federal Inspection Service from five regions of Brazil (north, northwest, west central, south, southeast). Survey sampling was divided into two stages: first one, a data set 1 (regional sampling) was collected only from the south during a year. This data sampling was used to estimate the data set 2 (national sampling). A largest extreme value was suggested as a model for caseinomacropeptide distributions for national sampling. The data set showed 2.52?mg?L?1 as the mean and 4.80?mg?L?1 for the standard deviation based on a sampling size of 170?units collected across Brazil. The findings are useful to understand the presence of caseinomacropeptide, especially when no adulteration or the absence of good practices is present. 相似文献
228.
Lucia Zetta Enrica Alberti Tiziano Motta Maurizio Canetti Fabio Bertini 《Journal of polymer science. Part A, Polymer chemistry》2007,45(20):4635-4646
Butadiene‐isoprene copolymerization with the system V(acac)3‐MAO was examined. Crystalline or amorphous copolymers were obtained depending on isoprene content. Both butadiene and isoprene units exhibit a trans‐1,4 structure and are statistically distributed along the polymer chain. Polymer microstructure, comonomer composition, and distribution along the polymer chain were determined by 13C and 1H NMR analysis. The thermal and X‐ray behaviors of the copolymers were also investigated and compared with results from solid‐state 13C NMR experiments. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4635–4646, 2007 相似文献
229.
P.M.A. de Farias B.S. Santos F.D. Menezes A.G. Brasil Jr. R. Ferreira M.A. Motta A.G. Castro-Neto A.A.S. Vieira D.C.N. Silva A. Fontes C.L. Cesar 《Applied Physics A: Materials Science & Processing》2007,89(4):957-961
Fluorescent semiconductor nanocrystals in quantum confinement regime (quantum dots) present several well-known features which
make them very useful tools for biological labeling purposes. Low photobleaching rates, high chemical stability and active
surface allowing conjugation to living cells explain the success of this labeling procedure over the commonly used fluorescent
dyes. In this paper we report the results obtained with highly fluorescent core–shell CdTe–CdS (diameter=3–7 nm) colloidal
nanocrystals synthesized in aqueous medium and conjugated to glucose molecules. The conjugated nanocrystals were incubated
with living yeast cells, in order to investigate their glucose up-take activity in real time, by confocal microscopy analysis.
PACS 87.83.+a; 61.46.Hk; 81.07.Ta 相似文献
230.
Cristiano Ruch Werneck Guimares Joaquim Delphino Da Motta Neto Ricardo Bicca De Alencastro 《International journal of quantum chemistry》1998,70(6):1145-1157
Higher plants use the protein phytochrome as a photosensor. In physiological temperatures phytochrome exists in two forms: Pr and Pfr. The chromophore of phytochrome is an open-chain tetrapyrrole. On the pathway from Pr to Pfr four intermediates (Lumi-R, Meta-Ra, Meta-Rb, and Meta-Rc) can be distinguished, while only two (Lumi-F and Meta-F) can be seen on the way back from Pfr to Pr. We have used the x-ray structure of the C-Phycocyanin protein Fremyella diplosiphon bacteria as a template to build a model (∼200 atoms) that includes only the chromophore and five amino acids of the phytochrome (Arg316–Cys321–His322–Leu323–Gln324) around it. Using the existing experimental evidences, we have proposed a three-dimensional (3D) structure for Pr, Pfr, and intermediates and a mechanism for the photoisomerization as well. Structures were fully optimized using AM1 (Unichem package on a Cray J90-NACAD). Using the INDO/S method of Zerner and co-workers, we calculated the absorption spectra of the model compounds and compared them with the experimental data. The oscillator strength ratio is an indicator of the chomophore conformation in biliproteins. The calculated spectra reproduces well the spectra of the phytochrome (Pr, Pfr, and intermediates) except for the lower energy band. This result is attributed to the small number of amino acids in the models. The calculated ratios (fVIS/fUV−fosc of visible band over fosc of UV band and f2/f1−fosc of second absorption band over fosc of first absorption band) for the models match very well the experimental ratios obtained for the phytochrome (Pr, Pfr, and intermediates). This supports the proposed mechanism for the photoisomerization process. © 1998 John Wiley & Sons, Inc. Int J Quant Chem 70: 1145–1157, 1998 相似文献