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1.
The behaviour of the oxinates of niobium, tantalum and associated metals in the infra-red region was studied and a method developed for the determination of niobium and tantalum. Vanadium caused no interference, but other heavy metals, such as molybdenum, manganese and cobalt, which interfered were removed by preliminary treatment when the method was applied to the determination of niobium and tantalum in steels. 相似文献
2.
Zusammenfassung Die Hemmung der katalytischen Jodwirkung auf die Redoxreaktion Cer(IV)-sulfat—arsenige Säure wird hinsichtlich ihrer Vorund Nachteile bei analytischer Anwendung untersucht. Brucinacetat gibt mit Ceriion in schwefelsaurer Lösung nachFischl eine quantitativ auswertbare Farbreaktion. Kritische Untersuchungen hierzu ergeben, daß die Lösungen zur vollen Entwicklung und Stabilität der orangeroten Farbe (Absorptionsmaximum 470 nm) mindestens 10 bis höchstens 12 Min. auf 105° zu erhitzen sind. Die Anwendung auf die Jodbestimmung im Blutserum nachSpitzy, Reese undSkrube bietet infolge methodischer Komplizierung keinen besonderen Vorteil.
Summary The inhibition of the catalytic action of iodine on the redox-reaction ceric sulphate—arsenious acid was investigated with regard to the advantages and disadvantages in its analytical application. Brucine acetate gives, according toFischl, a quantitative colour reaction with ceric ions in sulphuric acid. Critical investigations carried out show that the solution only develops a stable, orange-red colour (absorption maximum 470 nm) between 10 and 12 minutes heating. Application of this procedure to the determination of iodine in blood serum by the method ofSpitzy, Reese, andSkrube introduces complications and has, therefore, no special advantage.
Résumé Etude des avantages et des inconvénients de l'emploi en chimie analytique de l'inhibition de l'effet catalytique de l'iode sur la réaction d'oxydo-réduction cerium(IV)-sulfate—acide arsenieux. Avec les ions cériques l'acétate de brucine donne, en solution sulfurique, d'aprèsFischl, une réaction colorée susceptible d'être employée pour une détermination quantitative. Des recherches critiques ont montré que les solutions devaient être chauffées pendant au moins 10 min. et au plus 12 min. à 105° pour développer complètement la couleur rouge orangé et obtenir sa stabilité (maximum d'absorption à 470 nm). L'application à la détermination de l'iode dans le sérum sanguin d'aprèsSpitzy, Reese etSkrube n'offre aucun avantage particulier du fait de la complication de la méthode.相似文献
3.
The reduction of triphenyltin piperidyl dithiocarbamate in acetone has been investigated using d.c. polarography and cyclic
voltammetry. Polarographic reduction yielded four well-defined waves, two of which were diffusion-controlled and two of which
appear to represent adsorption processes. The cyclic voltammetric study yielded results in close agreement with the polarographic
data. Results appear to indicate the release of the dithiocarbamate moiety, followed by reduction to form the triphenyltin
radical, which undergoes dimerization, as well as reduction to the triphenyltin anion. For comparison, the polarographic reduction
of triphenyltinchloride was investigated. A mechanism similar to that proposed by earlier authors for the polarographic behaviour
of tributyltin oxide was found.
For convenience, the more commonly used terminology of piperidyl dithiocarbamate is used throughout the paper, in place of
(piperidine-1-carbodithioato) triphenyltin (IV). 相似文献
4.
We have performed parallel tempering Monte Carlo simulations using a simple continuum heteropolymer model for proteins. All 10 heteropolymer sequences which we have studied have shown first-order transitions at low temperature to ordered states dominated by single chain conformations. These results are in contrast with the theoretical predictions of the random energy model for heteropolymers, from which we would expect continuous transitions to glassy behavior at low temperatures. 相似文献
5.
6.
Nitrite reacts with dichromate quantitatively under suitable conditions of temperature and acid concentration. A linear relationship was found to exist between nitrite concentration and the absorbance at 580 nm of the chromium (III) species produced. This was used to determine the nitrite. The influence of a number of ions on the determination of nitrite was investigated; up to 100-fold excess nitrate has no influence on the determination of nitrite. 相似文献
7.
The infrared spectra of the 8-hydroxyquinolinates of molybdenum, vanadium and tungsten in the region 3–15 μ were investigated. It was found possible to determine the elements quantitatively, singly or in pairs, with an error of about 3%. Molybdenum was determined at 10.80 μ and 10.93 μ, vanadium at 10.50 μ, and tungsten at 10.61 μ or 10.90 μ. 相似文献
8.
We have used a flow calorimeter and a flow densimeter for measurements leading to apparent molar heat capacities and apparent molar volumes of dilute aqueous solutions of NaIO3, KMnO4, and MnCl2 at 25°C. These apparent molar quantities have been extrapolated to infinite dilution to obtain the corresponding standard state apparent and partial molar heat capacities and volumes. which have then been used for the calculation of conventional ionic heat capacities and volumes. 相似文献
9.
A spectrophotometric and a photometric titration method in a two-phase system for the determination of gold with ferroin is reported. Both methods are rapid and reproducible with an accuracy of ±1%. In the spectrophotometric determination Co2+, Cu2+, Ni2+ , Fe3+, Zn2+, Mn2+ and Cr3+ do not interfere with the determination of gold and Pt4+, Pd2+, Hg2+, Ir4+ and Os4+ can be tolerated up to a ratio of 1:1. The titrations can also be carried out in the presence of a number of diverse ions, e.g. Ni2+, Cu2+, Co2+, Fe3+, Zn2+, Cr3+, Mn2+, without interference; the platinum metals and Hg2+ cause interference but, by the use of the spectrophotometric procedure, this can be reduced. 相似文献
10.
Large Zero‐Field Splittings of the Ground Spin State Arising from Antisymmetric Exchange Effects in Heterometallic Triangles 下载免费PDF全文
Samantha A. Magee Dr. Stephen Sproules Dr. Anne‐Laure Barra Dr. Grigore A. Timco Nicholas F. Chilton Prof. David Collison Prof. Richard E. P. Winpenny Prof. Eric J. L. McInnes 《Angewandte Chemie (International ed. in English)》2014,53(21):5310-5313
[Ru2Mn(O)(O2CtBu)6(py)3] has an S=5/2 ground state with a very large zero‐field splitting (ZFS) of D=2.9 cm?1, as characterized by EPR spectroscopy at 4–330 GHz. This is far too large to be due to the MnII ion (D <0.2 cm?1), as shown from the {Fe2Mn} analogue, but can be modeled by antisymmetric exchange effects. 相似文献