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81.
W. Sterzel E. -J. Zehnder und E. Rodek 《Fresenius' Journal of Analytical Chemistry》1976,282(1):37-41
Zusammenfassung Durch Symmetrieerniedrigung der Carbonationen an der Oberfläche von Calcitpräparaten wird die infrarotverbotene symmetrische Valenzschwingung aktiviert.Aus der Intensität dieser Infrarotabsorption kann auf die Oberflächenentwicklung geschlossen werden. Am Beispiel von Cadmiumcarbonat wird durch Vergleich dieser Messungen mit röntgenographischen Methoden der Teilchengrößenbestimmung und BET-Messungen der spezifischen Oberflächen gezeigt, daß die Methode geeignet ist, schnelle Oberflächenbestimmungen durchzuführen.Wir. danken der Deutschen Forschungsgemeinschaft und dem-Verband der Chemischen Industrie für die Förderung dieser Arbeit. 相似文献
82.
Safoklov B. B. Atovmyan E. G. Nikonova L. A. Tkachev V. V. Aldoshin S. M. 《Russian Chemical Bulletin》2002,51(12):2224-2229
Pyrrole-2-carbaldehyde isonicotinoylhydrazone (1) and its hydrate [1·H2O] (2) were studied by single-crystal X-ray diffraction analysis. The introduction of the pyrrole substituent into N"-substituted isonicotinic hydrazide (INH) causes the intramolecular redistribution of the electron density compared to those in INHs studied earlier, which increases the basicity of the hydrazone nitrogen atom (N") involved in intermolecular hydrogen bonding. This effect has not been observed in the structures of N"-substituted INHs and benzhydrazides studied previously. Intermolecular hydrogen bonds play a decisive role in the formation of the crystal structures of 1 and 2. 相似文献
83.
A compound of the formula Fe3Mg2Mo2V3O20 has been obtained as a result of a reaction between FeVO4 and MgMoO4 taken at a molar ratio of 3:2. This compound crystallises in the monoclinic system and its unit cell parameters are the following:
a=0.6971 nm, b=0.9055 nm,c=1.2542 nm, g=102.00°, Z=2.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
84.
Esko Taskinen 《Structural chemistry》2002,13(1):61-71
Selected group frequencies of the IR spectra of a number of 2-substituted 4-methylene-1,3-dioxolanes (a) and their endocyclic isomers, 2-substituted 4-methyl-1,3-dioxoles (b), have been studied to establish their usefulness as a measure of the strength of p– conjugation in the O—C=C moieties of the title compounds. In the exo compounds (a), the C=C stretching frequencies C=C and the in-phase, out-of-plane bending (wagging) frequencies CH2
w of the =CH2 group were found to be linearly related, besides to each other, also to the electron-donating character of the substituents and the 13C NMR chemical shift of the C atom of the exocyclic CH2 group. This suggests that the two IR group frequencies of the exo isomers are linearly related to the strength of p– conjugation in the O—C=C moiety. The C=C stretching absorption of the exo compounds in the 1600–1700 cm–1 region appeared as a doublet, shown to arise from Fermi resonance of the C=C fundamental with the CH2
w overtone. The C=C frequencies of the endo compounds support some previous findings of an unexpected strength of p– conjugation in the 2-alkoxy derivatives. Finally, DFT calculations at the B3LYP/6-31G* level of theory are shown to give accurate predictions of the effect of 2-substituents on the group frequencies. 相似文献
85.
I. I. Chuev S. M. Aldoshin E. G. Atovmyan D. B. Frolov A. N. Utenyshev 《Russian Chemical Bulletin》1996,45(4):851-855
N-Thenylidene- andN-(o-nitrobenzylidene)hydrazides of isonicotinic acid have been studied by X-ray structural analysis and IR spectroscopy. In the crystalline state, these molecules are linked through intermolecular N—H ... Npy hydrogen bonds. Carbonyl groups are not involved in intermolecular hydrogen bonds. However, it was found that the C=O group participates in an attractive interaction with the sulfur atom of the thiophene group. The energy of this interaction is comparable with the energies of intermolecular C=O ... H—N hydrogen bonds in amides.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 896–900, April, 1996. 相似文献
86.
The thermal decomposition of Co(NO3)2·6H2O (1) as well as that one of NO[Co(NO3)3] (Co(NO3)2·N2O4) (2) was followed by thermogravimetric (TG) measurements, X-ray recording and Raman and IR spectra. The stepwise decomposition reactions of 1 and 2 leading to anhydrous cobalt(II)nitrate (3) were established. In N2 atmosphere, cobalt oxides are finally formed whereas in H2/N2 (10% H2) cobalt metal is produced. Rapid heating of cobalt(II)nitrate hexahydrate causes melting (formation of a hydrate melt) and therefore side reactions in the hydrate melt by incoupled reactions and evolution/evaporation of different species as, e.g., HNO3, NO2, etc. In case of larger amounts in dense packing in the sample container, the formation of oxo(hydoxo)nitrates is possible at higher temperature. For 2, its thermal decomposition to 3 was followed and its decomposition mechanism is proposed. 相似文献
87.
A new complex of europium(II) with ethylenediaminetetraacetic acid was obtained by electrochemical reduction. The compound is composed of polymeric chains, guanidinium cations and water molecules. The Eu2+ cation is eight‐coordinate (two nitrogen atoms and six carboxylate oxygen atoms), and contrary to europium(III) complexes with edta, does not contain water molecules in the first coordination sphere. Relationships between the coordination mode and IR as well as UV–Vis spectra are discussed. 相似文献
88.
The v(OH) frequency shifts of phenol and the vR resonance components of these shifts in the IR spectra of phenol H-complexes with ethylene derivatives containing various substituents including organosilicon, organogermanium, and organotin groups have been studied. The relationship between v and vR and the values that characterize the influence of substituents on the effective charges of the double bonded carbon atoms was established; the latter values have been calculated previously usingab initio quantum chemical methods. The effective charges for the compounds with organoelemental substituents have been calculated. It has been elucidated that of the two types of possible interactions, charge controlled and orbital controlled, occurring in the formation of a complex of a hard acid, phenol, with the studied ethylene derivatives, the former is predominant.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1383–1387, August, 1993. 相似文献
89.
90.
Capacitive micromachined ultrasonic transducers (CMUTs) bring the fabrication technology of standard integrated circuits into the field of ultrasound medical imaging. This unique property, combined with the inherent advantages of CMUTs in terms of increased bandwidth and suitability for new imaging modalities and high frequency applications, have indicated these devices as new generation arrays for acoustic imaging. The advances in microfabrication have made possible to fabricate, in few years, silicon-based electrostatic transducers competing in performance with the piezoelectric transducers. This paper summarizes the fabrication, design, modeling, and characterization of 1D CMUT linear arrays for medical imaging, established in our laboratories during the past 3 years. Although the viability of our CMUT technology for applications in diagnostic echographic imaging is demonstrated, the whole process from silicon die to final probe is not fully mature yet for successful practical applications. 相似文献