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1.
E. Schnell W. Kiesewetter Y. H. Kim E. Hayek 《Monatshefte für Chemie / Chemical Monthly》1971,102(5):1327-1336
Zusammenfassung Die für den Einbau in die Calciumphosphate der Knochensubstanz in Frage kommenden Strontiumphosphate wurden auf ihre Existenzbedingungen untersucht. Oktacalciumphosphat tauscht in verd. Lösungen einige Prozente des Calciums gegen Strontium aus. Obwohl der Struktur nach apatitartige Strontiumphosphate zwischen Sr/P=1.33 und 1.67 erhältlich sind, läßt sich ein röntgenoptisch reines Strontiumoktaphosphat nicht isolieren, jedoch ein solches mit kleinem Carbonatgehalt und — leicht — die den Calciumsalzen analogen Strontiumphosphatcarbonate verschiedener Zusammensetzung. Im Hydrothermalbereich (375o) sind je nach relativer Zusammensetzung des Strontiumphosphat-Systems SrHPO4, Sr2P2O7, Sr2(PO4)2 und Sr5(PO4)3OH stabil und gut kristallin erhältlich. Das Salz Sr6H3(PO4)5 läßt sich aus Lösungen von Strontiumphosphaten in Kohlensäure-Wasser, H2S-Wasser und in einem Barbiturat-Puffersystem rein darstellen.
Mit 2 Abbildungen
Herrn Prof. Dr. Dr. h. c.Hans Nowotny gewidmet. 相似文献
Ortho strontium phosphates
Strontium phosphates which possibly are being incorporated into the calcium phosphates of bony tissue were investigated. Octacalcium phosphate in dilute solutions exchanges a few percent of calcium against strontium. While strontium phosphates with apatite-like structures, and with ratios of Sr/P between 1.33 and 1.67 can be prepared, no pure strontium octaphosphate, as a distinctive X-ray phase can be isolated. Only preparations with small amounts of carbonate, as well as strontium phosphate carbonates analogous to the corresponding calcium salts can be obtained. At hydrothermal conditions (375o), the compounds SrHPO4, Sr2P2O7, Sr3(PO4)2 and Sr5(PO4)3OH are stable, and can be prepared in well cristallized form, depending on the relative composition of the strontium phosphate system. The salt Sr6H3(PO4)5 can be prepared in a pure state from solutions of strontium phosphates in aqueous solutions of carbonic acid, H2S and barbiturate buffer systems.
Mit 2 Abbildungen
Herrn Prof. Dr. Dr. h. c.Hans Nowotny gewidmet. 相似文献
2.
E. Schnell 《Monatshefte für Chemie / Chemical Monthly》1962,93(5):1136-1141
Zusammenfassung Die Verbindung SiF4·N(CH3)3 ist in Benzol löslich und daraus in nadelförmigen Kristallen erhältlich, während SiF4·2 N(CH3)3 als in Petroläther schwer löslicher Niederschlag gewonnen werden kann. IR-Spektren beider Verbindungen werden mitgeteilt.Mit 2 Abbildungen 相似文献
3.
In solid-state NMR, deuteron (2H) spectroscopy can be performed in full analogy to1H spectroscopy, including2H chemical-shift resolution and2H-X dipolar correlation schemes, when the NMR experiments are conducted in a “rotor-synchronized” fashion under fast magic-angle
spinning. Here, 2H-X NMR experiments of this type, including2H-15N and2H-1H chemical-shift correlations and distance measurements, are introduced and demonstrated on cytosine monohydrate, whose acidic
protons can readily be replaced by deuterons by recrystallization from D2O. In this way,2H NMR spectroscopy provides information complementary to1H NMR data, which is particularly useful for studying hydrogen bonds in supra- or biomolecular systems.
Electronic supplementary material Supplementary material is available in the online versionof this article atand is accessible for authorized users. 相似文献
4.
Multireference configuration interaction calculations are carried out for ground and excited states of dichloromethanol, Cl2CHOH, to investigate two important photofragmentation processes relevant to atmospheric chemistry. Five low-lying excited states (1(1)A", 2(1)A', 1(3)A", 2(3)A" and 1(3)A') in the energy range between 6.4 and 7.5 eV are found to be highly repulsive for C-Cl elongation, leading to ClCHOH (X2A) and Cl (X2P). Photodissociation along the C-O bond resulting in CHCl2 (X2A') and OH (X2II) has to overcome a barrier of about 0.5 eV because the low-lying excited states 1(1)A", 1(3)A' and 1(3)A" become repulsive only after the C-O bond is elongated by about 0.3 A. 相似文献
5.
E. Schnell 《Monatshefte für Chemie / Chemical Monthly》1963,94(4):703-713
Zusammenfassung Die Intensität der K-Strahlung von 27 Verbindungen der Elemente S, P. Si und Al wird mit der Intensität der K-Strahlung verglichen. Sie ist abhängig vom jeweiligen Element, von dessen Oxydationsstufe und vom Verbindungspartner. Für die Sauerstoffverbindungen ist die mit steigender Oxydationsstufe zunehmende Intensität des langwelligen Satelliten K' charakteristisch.Mit 4 Abbildungen 相似文献
6.
Solid-state 2H NMR spectroscopy is a well-established and versatile method to study molecular orientation and dynamics in selectively deuterated samples. Herein, we introduce a 2D 2H double-quantum (DQ) NMR experiment performed under fast magic-angle spinning with a slight offset of the magic angle (OMAS). The experiment combines 2H chemical-shift resolution with DQ-filtered quasistatic 2H line shapes. In this way, it is possible to separate 2H resonances and to independently determine 2H quadrupole couplings at multiple sites. While 2H chemical shifts are resolved in the 2H DQ dimension, the quadrupole parameters can be obtained from characteristic line shapes which are reintroduced in the second dimension by the magic-angle offset. The 2D 2H DQ OMAS experiment is demonstrated on L-histidine which was deuterated at multiple sites by recrystallisation from D2O. 相似文献
7.
High-performance thin-layer chromatographic (HPTLC) analysis of non UV-active phospholipids in biological matrixes is a common method for separation, detection, and quantitation. Liposomes containing new alkylphosphocholines and analogues with enhanced cytostatic activity had been prepared. The liposomal formulations were designed to enable the intravenous application of the alkylphosphocholines and analogues and to reduce dose-limiting toxicities observed after oral administration. For quality control the liposomes were analyzed by HPTLC for content of 1,2-dipalmitoyl-sn-glycero-3-phosphoglycerol (DPPG), cholesterol, alkylphosphocholines, and analogues and their related compounds (main degradation products). Due to the differences in lipophily of the compounds, different mobile phases were necessary to achieve separation. Automated Multiple Development was used to reduce the number of plates and to improve the selectivity and the capacity of the chromatographic system to separate the described alkylphosphocholines and analogues from DPPG and 1,2-dipalmitoyl-sn-glycero-3-phosphocholine in one chromatographic system. 相似文献
8.
Zusammenfassung Der Spitzenentladungsdetektor wird bei gaschromatographischen Trennungen mit Stickstoff als Trägergas angewendet. Bei Verwendung der positiven Korona muß der reine Stickstoff mit 0,5–3 Vol% Sauerstoff dotiert werden, um eine empfindliche Anzeige organischer Substanzen zu erzielen. Bei Verwendung als Funkendetektor mit negativer Spitze ist der Detektor hochempfindlich und kann als halogenspezifisch bezeichnet werden.
Herrn Prof. Dr. E. Hayek zum 70. Geburtstag gewidmet. 相似文献
The point discharge detector with nitrogen as carrier gas in gas chromatography
Summary The point discharge is employed in gas chromatographic separations with nitrogen as carrier gas. When the positive corona is employed the pure nitrogen must be enriched with 0.5–3 volume percent of oxygen in order to attain a sensitive indication of organic substances. When a spark detector with negative points is used, the detector is highly sensitive and can be characterized as halogenspecific.
Herrn Prof. Dr. E. Hayek zum 70. Geburtstag gewidmet. 相似文献
9.
10.
Srgio R. Domingos Kvin Martin Narcis Avarvari Melanie Schnell 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(33):11379-11383
We report on the one‐ and two‐water clusters of [4]helicene, the smallest polycyclic aromatic hydrocarbon with a helical sense, which were captured in the gas phase using high‐resolution rotational spectroscopy. The structures of the complexes are unambiguously revealed using microwave spectra of isotopically enriched species. In the one‐water cluster, the apparent splitting pattern is consistent with a tunneling motion that encompasses an exchange of strongly and weakly bonded water hydrogens. This motion is “locked” in the two‐water cluster. The relevant intermolecular contacts, symmetry, and aromaticity effects are unveiled for the microsolvated chiral topologies. These observations entail the first glance at the structures and internal dynamics of the water binding motifs of a chiral polycyclic aromatic hydrocarbon. 相似文献