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1.
Marius Rebek Josef Schurz Walter Stöger Wolfgang Popp 《Monatshefte für Chemie / Chemical Monthly》1969,100(2):532-539
Zusammenfassung Die vorliegende Arbeit stellt eine Beschreibung von Experimenten dar, die die Erhöhung der Pfropfbereitschaft von trägen Komponenten durch Beimischung von aktiveren zum Ziele hatten.Das Trägermolekül war in allen Fällen Cellulose in Form von hochgradig gereinigtem Zellstoff. Durch die Verwendung von Mischsystemen aus Styrol und Methylmethacrylat gelang es, das trägere Styrol in bedeutend größerer Menge auf die Cellulose aufzupfropfen, als es bei Abwesenheit des aktiven Methylmethacrylats der Fall war.
Nach einem Vortrag, den der erstgenannte der Autoren im Rahmen der Arbeitstagung des Vereins Österreichischer Chemiker am 27. September 1968 in Wien gehalten hat. 相似文献
Grafting Polymerization of Cellulose with Two Vinyl Monomers
This paper describes experiments to increase the grafting of cellulose with components of poor reactivity by mixing them with highly reactive ones. A highly purified wood pulp was used as backbone. Using combinations of styrene and methyl methacrylate it was possible to graft considerably higher amounts of the poorly reacting styrene than in the absence of the highly reactive methyl methacrylate.
Nach einem Vortrag, den der erstgenannte der Autoren im Rahmen der Arbeitstagung des Vereins Österreichischer Chemiker am 27. September 1968 in Wien gehalten hat. 相似文献
2.
K. Lederer R. Hammel J. Schurz K. -H. Janzon 《Monatshefte für Chemie / Chemical Monthly》1972,103(5):1299-1314
Zusammenfassung Es werden die mittleren Dimensionen der Teilchen dreier Kieselsäuresole mit derRKWS und demE. M. bestimmt. Entgegen der Angabe anderer Autoren ergibt sich dabei bei Berücksichtigung der Teilchengrößenverteilung nahezu völlige Übereinstimmung beider Methoden.RKWS undE. M. ergeben angenähert auch die gleiche mittlere Schwankung
m
der Teilchendurchmesser. Die mit derRKWS bestimmte spezifische Oberfläche ist stets größer als die aus der N2-Adsorption bestimmte, und zwar nimmt der relative Unterschied mit dem mittleren Teilchendurchmesser zu. Die mit derRKWS bestimmte innere Hydratation liegt bei 0,15–0,26 g H2O/g SiO2.
Mit 8 Abbildungen
Herrn Professor Dr. Dr. h. c.Otto Kratky zum 70. Geburtstag mit den herzlichsten Glückwünschen gewidmet. 相似文献
Characterization of silica sols by means of X-ray small angle scattering, electron microscopy and nitrogen adsorption
X-ray small angle scattering and electron microscopy are used to determine average dimensions of particles in three silica sols. In contradiction to findings of other authors, a nearly complete agreement of both methods is found if the particle size distribution is taken into account. Identical average variations m of the particle diameters are obtained for both methods. The inner surface determined by means of the X-ray small angle scattering is in all cases larger than that obtained from N2-adsorption, the difference increasing with average particle diameter. The inner hydration determined by means of the X-ray small angle scattering lies at 0.15–0.26 g H2O/g SiO2.
Mit 8 Abbildungen
Herrn Professor Dr. Dr. h. c.Otto Kratky zum 70. Geburtstag mit den herzlichsten Glückwünschen gewidmet. 相似文献
3.
The importance of the rheological behaviour of solutions of macromolecules is briefly evaluated. The viscosity of the solutions depends on concentration, shear rate and time of shear, this relation being determined by the structure of the dissolved molecules. In dilute solutions shear dependence of viscosity is very frequently caused by the preferential orientation of anisotropic molecules. In such a case the particle dimensions can be calculated from the true limiting viscosity number, an anisotropy factor, the rotational diffusion constant and the effective particle density. These numbers can be derived from the flow curve, which has been extrapolated to zero concentration. It is necessary to measure the flow curve at shear gradients, which are sufficiently low to allow for an extrapolation to vanishing shear rate. By comparing the experimental flow curve with a choice of theoretical ones, the rotational diffusion constant and the anisotropy factor (axial ratio) can be found. From the limiting viscosity number and the axial ratio, the particle density can be calculated. 相似文献
4.
Reaction of Na2O2NN' [H2O2NN' = (2-C5H4N)CH2N[2-HO-3,5-C6H2(t)Bu2]2] with M(BH4)3(THF)3 afforded the dimeric, rare-earth borohydride compounds [M(O2NN')(mu-BH4)(THF)n]2 [M = Y(III), n = 0.5 (1-Y); M = NdIII, n = 1 (1-Nd); M = SmIII, n = 0 (1-Sm)]. For comparison the chloride analogues [M(O2NN')(mu-Cl)(THF)n]2 (2-M; M = La(III) or Sm(III), n = 0; M = Nd(III), n = 1) and the corresponding pyridine adducts [M(O2NN')(mu-X)(py)]2 [X = BH4 (3-M) or Cl (4-M); M = La(III), Nd(III), or Sm(III)] were prepared and structurally characterized for 4-La. Compounds 1-M initiated the ring-opening polymerization of epsilon-caprolactone. The best molecular weight control (suppression of chain transfer) for all three monomers was found for the samarium system 1-Sm. The most effective heterotactic enrichment (Pr) in the polymerization of rac-lactide was found for 1-Y (P(r) = 87%). Compound 1-Nd catalyzed the block copolymerization of epsilon-caprolactone and L- and rac-lactide provided that epsilon-caprolactone was added first. Attempted block polymerization by the addition of L-lactide first, or random copolymerization of a ca. 1:1 mixture of epsilon-caprolactone and L-lactide, gave only a poly(L-lactide) homopolymer. 相似文献
5.
Hans-Jörg Jacobasch Günther Bauböck Josef Schurz 《Monatshefte für Chemie / Chemical Monthly》1986,117(10):1133-1144
An apparatus for the determination of zetapotential is described, which allows measurement of both streaming potential and streaming current as well as electroosmosis with one and the same fiber diaphragm with various electrodes (calomel, Ag/AgCl, palladium). Measurements with glass fibers, fibers of polyacrylonitrile and of polyester, and with cellulose pulp show that identical values for the electrokinetic parameters are obtained independent of voltage applied during electroosmosis resp. pressure difference during streaming measurements. This allows the conclusion that the zetapotential in dilute electrolyte solution is here an unequivocally determinable figure.
Herrn Prof. Dr.R. C. Schulz mit den herzlichsten Glückwünschen zum 65. Geburtstag gewidmet. 相似文献
6.
Behaviour of water-soluble dinuclear rhodium complexes in the hydroformylation reaction of oct-1-ene
The biphasic hydroformylation reaction of oct-1-ene, has been investigated by using the water-soluble dinuclear complex [Rh2(μ-StBu)2(CO)2(TPPTS)2] as precursor. Addition of ethanol as a cosolvent dramatically improved the yields but the good regioselectivity in linear aldehyde observed for neat oct-1-ene—water systems (97%) decreased to 83% (for 22% ethanol w/w). It is shown that the dinuclear framework cannot be maintained, that the mononuclear complex [RhH(CO)(TPPTS)3] is formed, and that thiol and significant amounts of [Rh2(μ-StBu)2(CO)4] move into the organic phase. This reaction from the dinuclear species requires the simultaneous presence of water and carbon monoxide. Introduction of the water-soluble thiol HS(CH2)3NMe2 in the bridging positions affords the complex [Rh2(μ-S(CH 2)3NHMe2)2(CO)2(TPPTS)2]Cl2 which can be kept in the aqueous hase but has a low level of catalytic activity. 相似文献
7.
Changes of the rheological properties of hyaluronic acid (sodium-magnesium salt) solutions after exposure to UV radiation
indicate a vigorous decrease in their viscosity, but its still strong shear rate dependence. Whereas the presence of the singlet
oxygen sensitizer (anthracene-1-sulphonic acid) brings about a loss of shear dependence; the studied solutions show newtonian
behavior. 相似文献
8.
Thermal silazane cleavage of dichloroboryldisilylamines (SiClmMe3?m)N(SiMe3)(BCl2) (1: m = 1; 2: m = 2) at 196 °C leads to the borazine derivates [(SiClmMe3?m)NB(ClnMe1?n)]3 (3: m = 1, n = 0.185; 4: m = 2, n = 0.111) characterized by NMR and IR spectroscopy and mass spectrometry. Single‐crystal X‐ray diffraction structure analyses reveal (BN)3 units with unusual twisted boat conformations in both compounds. Additionally, more detailed studies are done to clear up the function of the by‐products (SiClmMe3?m)N(SiClMe2)(BClMe) formed during the cyclization step leading to asymmetrically boron substituted borazine derivatives. The single‐source precursors 3 and 4 were cross‐linked with methylamine producing polymers 3P and 4P, which were transformed into black amorphous materials with ceramic yields of 20.8 % and 50.3 %, respectively. Ceramic 4C (Si1.00B0.98 N2.55 C1.37O0.05) was further investigated by 11B and 29Si magic angle spinning (MAS) NMR spectroscopy. A combined study of high‐temperature TG analyses and X‐ray powder diffraction analyses confirms the thermal stability of 4C up to 1670 °C. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
9.
Fanny Danton Dr. Mohamed Othman Dr. Ata Martin Lawson Dr. Ján Moncol Dr. Alina Ghinet Prof. Benoît Rigo Prof. Adam Daïch 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(24):6113-6118
An efficient domino transformation using a phenyliodine(III) diacetate (PIDA)/I2 combination towards Morin 1,4-thiazine compounds has been developed starting from N,S-acetals. The latter leads to “one-step” regioselective methylene insertion without the need for traditional sulfoxide intermediates in good yields. The reaction involves easily accessible N,S-acetals obtained from cost-effective basic ketones and cysteamine as starting materials. This process ultimately leads to 1,4-thiazines related to natural product and fused derivatives necessary for further QSAR study. 相似文献
10.
Josef Schurz Gayyur Erk Walter Schempp Volker Ribitsch 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(13-14):1673-1692
Polymers with electrically charged groups exhibit a zeta potential when in contact with electrolyte solutions in water. This can be measured with solid polymers as fibers, foils, or granulates. The method of streaming potential/streaming current allows the determination of the carboxyl content of cellulose grafted with poly-(acrylic acid). Since zeta-potential measurements concern the surface of the sample, the method yields information on the type of grafting; i.e., whether it takes place mainly on the surface or throughout the bulk. By measuring the pH dependence of the zeta potential it is possible to obtain the pK value of the charged groups. The significance of zeta potential as an analytical tool is emphasized. 相似文献