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1.
S Barcza 《Journal of computer-aided molecular design》1991,5(6):509-510
Unlike in other branches of science and technology, computer programs and algorithms are generally not fully disclosed. This leads to duplication of effort, and prevents building new knowledge rapidly on existing knowledge. To remedy this, effective patents on computer programs and algorithms should be granted. The community of authors and inventors, along with expert advice from patent attorneys, have to arrive at effective and equitable definitions of obviousness and novelty, so that the boundaries of protection on one side, and free progress on the other, can be defined. The same reasons exist for patenting and disclosing computer software knowledge as for chemistry, electrical and mechanical inventions. Patenting has protected inventors and assured progress for many decades successfully in these fields. 相似文献
2.
Quantitation of protein 3-D structure similarity is crucial in such fields as evolutionary studies, structural modeling and prediction of biological function. There are various approaches, many of which are tailored to specific problems. This review summarizes the recent developments in this field with particular interest in two main areas: i) improvements to and statistical interpretation of the root-man-square distance between equivalent atoms, rmsd; and ii) methods of protein structural classification based on geometrical features. Special attention is given to fast methods capable of analyzing large structural databases. 相似文献
3.
L. Barcza und L. Sommer 《Fresenius' Journal of Analytical Chemistry》1963,192(2):304-308
Zusammenfassung Bei dem Nachweis von Selen(IV) mit 3,3-Diaminobenzidin konnte man nach der Extraktion von Piazselenol mit Toluol bei pH 6,0–8,0 die Empfindlichkeit pD 7,3 erreichen. Die Reaktion ist aber auch bei dieser Ausführung nicht so selektiv, wie man bisher angenommen hat. Erst wenn das Selen als Selentetrabromid in Gegenwart von Brom in konzen-trierter Schwefelsäure vor dem Nachweis durch Destillation in einer einfachen Anlage abgetrennt worden ist, wird der Nachweis spezifisch. Die Reaktion ist dann zum Nachweis von Selen bis 2·10–5% in Pyriten und 5·10–7% in technischer Schwefelsäure geeignet.
Wir danken den Herren Professor Dr. E. Schulek und Professor Dr. A. Oka herzlich für Ihr Interesse an dieser Arbeit.
Beiträge zur Chemie des Selens und der Selenverbindungen. VIII. (VII. Mitt.: Acta chim. Acad. Sci. hung., im Druck.) 相似文献
Summary The sensitivity of the known reaction of selenium(IV) with 3,3-diaminobenzidine is pD 7,3, if piazselenole has been extracted by toluene at ph 6,0–8,0. This reaction is not so selective as it has been believed hitherto now. Yet it is specific after a preceding separation of selenium as selentetrabromide in the presence of bromine from conc. sulphuric acid according to a simple procedure. Using a microdestillation apparatus 2·10–5% of selenium in pyrites and 5·10–7% in technical sulphuric acid can be detected.
Wir danken den Herren Professor Dr. E. Schulek und Professor Dr. A. Oka herzlich für Ihr Interesse an dieser Arbeit.
Beiträge zur Chemie des Selens und der Selenverbindungen. VIII. (VII. Mitt.: Acta chim. Acad. Sci. hung., im Druck.) 相似文献
4.
L.N. Domelsmith K.N. Houk J.W. Timberlake Sandor Szilagyi 《Chemical physics letters》1977,48(3):471-476
The photoelectron spectrum of 3,3,4,4-tetramethyldiazetine (4-Me4) has been measured. By comparison with the previously reported photoelectron spectra of 3,3-dimethyldiazirine and 3,3,5,5-tetramethylpyrazoline, 4-Me4 has three resolved low energy ionization (8.87, 10.36, and 11.65 eV) with an anomalously low second ionization potential. MINDO/3-and ab initio STO-3G calculations on 3-, 4-, and 5-membered ring azo compounds (diazenes) have been carried out, and these allow definite conclusions about the order of n?, n+, and π ionization potentials to be made for the diazetine (n? < N+ < π) and for 3,3-dimethyldiazirine and 3,3,5,5-tetramethylpyrazoline(n? < π n+), in agreement with the predictions of Heilbronner. Ab initio STO-3G calculations on the nitrogen and alkyl fragments of the cyclic diazenes reveal the origin of ionization energy shifts with changes in ring size. 相似文献
5.
A large succinic acid (HOOC(CH2)2COOH) matrix containing 7 × 7 × 7 unit cells with guest oligonucleotide AGCAGCT was modeled with molecular dynamics simulation
for infrared matrix-assisted laser desorption ionization. We simulated the laser heating of the succinic acid (this data is
still missing from the literature) with λ=2.94 μm infrared laser pulses and compared it to ultraviolet excitation. We did
this in order to elucidate the cluster formation of succinic acid in the gas phase in itself and around the analyte. At this
wavelength, the laser energy is coupled into the matrix through the OH vibrations of the carboxyl groups. The most pronounced
difference we observed at 1,500 K simulation is that infrared heating generates about 10–15 more succinic acid molecules bound
to the analyte in noncovalent complex form than the ultraviolet mode, which generates about 2 molecules thus bound. We report
energy redistribution within the matrix between the host and guest species as well as other dynamical properties. The parameter
and topology data for succinic acid that we used are reported and ready for use in CHARMM computer code environment for simulation.
Revised: 12 October 2001 / Accepted: 27 February 2002 / Published online: 13 June 2002 相似文献
6.
Aacute;gnes Buvári-Barcza Antal Csámpai Lajos Barcza 《Journal of inclusion phenomena and macrocyclic chemistry》2002,42(3-4):209-212
Two guests reacting with cyclodextrins (CDs) may form ternary complexes, in addition to the common competition of 1:1 complexes. One of the guests can really be included into the cavity of the CD, while the second guest molecule is either inserted close to the first one or attached to the outer surface of the supramolecule by H-bonding. There is a further possibility when the included guest bears a substituent outside the cavity and the second guest can interact with it. The properties of the ternary species formed are highly influenced by the solely (or primarily) included guest. The changes are attributed to the altered properties of the hydrophilic domain of the CD. The phenomena can be proved by NMR data obtained for some binary systems of -CD inclusion complexes and acetic acid and by the stability constants of the ternary complexes formed. Allosteric effects as well as coenzyme/apoenzyme/substrate interactions could be well modelled by these types of CD complexes. 相似文献
7.
Productive proton pumping by bacteriorhodopsin requires that, after the all-trans to 13-cis photoisomerization of the retinal chromophore, the photocycle proceeds with proton transfer and not with thermal back-isomerization. The question of how the protein controls these events in the active site is addressed here using quantum mechanical/molecular mechanical reaction-path calculations. The results indicate that, while retinal twisting significantly contributes to lowering the barrier for the thermal cis-trans back-isomerization, the rate-limiting barrier for this isomerization is still 5-6 kcal/mol larger than that for the first proton-transfer step. In this way, the retinal twisting is finely tuned so as to store energy to drive the subsequent photocycle while preventing wasteful back-isomerization. 相似文献
8.
János Gyimesi Éva Szökő Kálmán Magyar Lajos Barcza 《Journal of inclusion phenomena and macrocyclic chemistry》1996,25(1-3):253-256
Binding constants of the optical isomers of Deprenyl® (selegiline) and its potential metabolites with (2,6-di-O-methyl)--cyclodextrin were determined using electrophoretic mobility data gained from separations performed by capillary electrophoresis, and absorbancies obtained from spectrophotometric experiments. To calculate equilibrium constants l: l complex formation have been assumed. The comparison of the equilibrium constants calculated from different methods shows similar values in their order of magnitude. Their difference may probably be explained by the different media of the measurements. The effect of the structure of compounds on chiral discrimination were also elucidated. 相似文献
9.
The reliability of measurement results is essential for forming a common database of a laboratory network, because a well-maintained and consistent database is the crucial point of countrywide monitoring. Reference materials are important tools in realizing some aspects of quality assurance; they are especially useful in harmonizing work within the network. Among usual types of reference materials in radio analytics solutions, matrix reference materials and some special reference objects are used. All classes of reference materials should be used depending on the purpose of the demonstration of quality, even in-house reference materials. Interlaboratory measurement comparison and performance evaluation programs play important quality assurance role in radio analytical laboratories. Fortunately, nowadays, the main task is to determine a very low radioactivity concentration in the environment; therefore, pre-concentration is necessary. Generally, the radionuclide bearing natural materials collected from sites where there had been sufficient time for natural processes to redistribute various chemically different species of radionuclides are more reliable reference materials than spiked materials—the main difference is the chemical bounding which is crucial from the point of view of the bioavailability. The need of reference material is summarized according to the intended use, like quality control, measurement validation, and instrument calibration. 相似文献
10.
The effect of cationic and anionic surfactants, as well as cationic and anionic polyelectrolytes (PE), their binary mixtures on the electrokinetic potential of monodisperse carboxylated polystyrene (PS) particles as a function of the reagents dose, pH, the charge density (CD) of polymers, the surfactant/PE and binary PE mixture composition, and sequence of components addition to the suspension has been studied. It has been shown that addition of increasing amount of anionic surfactant/polyelectrolytes increases the absolute value of the negative zeta-potential of PS particles; this increase is stronger the CD of the PE and pH of the system are higher. Adsorption of cationic surfactant/polyelectrolytes leads to a significant decrease in the negative ζ-potential and to overcharging the particles; changes in the ζ-potential are more pronounced for PE samples with higher CD and for suspensions with lower pH values. In mixtures of cationic and anionic PE, in a wide range of mixture composition, the ζ-potential of particles is determined by the adsorbed amount of the anionic polymer independently of the CD of PEs and the sequence of addition of the mixture components. The isoelectric point of the surface is reached at the adsorbed amount of positive charges of PE that is approximately equal to the surface CD of particles. The laws observed were explained by features of macromolecules conformation in adsorbed mixed PE layers. Considerations about the role of coulombic and non-coulombic forces in the mechanism of anionic/cationic PE adsorption are presented. 相似文献