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511.
Wojciech Swisterski Adam Wróblewski Michał Życzkowski 《International Journal of Non》1983,18(4):287-296
Optimality of geometrically non-linear eccentrically compressed columns of uniform strength in creep conditions is investigated. A third-order theory with siretehability of axis taken into account is employed. Norton's non-linear creep law and Kachanov's hypothesis of brittle creeprupture is used and an I-column of uniform strength for a given life-time is numerically evaluated. Then this column is. found to be non-optimal and a futher parametrical optimization is performed under the constraint of constant volume of the constant volume of the column. The life-time of the optimal column is considerably increased. 相似文献
512.
K. Rykaczewski I. S. Grant R. Kirchner O. Klepper V. T. Koslowsky P. O. Larsson E. Nolte G. Nyman E. Roeckl D. Schardt L. Spanier P. Tidemand-Petersson E. F. Zganjar J. Żylicz 《Zeitschrift für Physik A Hadrons and Nuclei》1985,322(2):263-270
Using the40Ca(4.2 MeV/u) +60Ni reaction and on-line mass separation, the decay properties of 46 96 Pd50 were reinvestigated. From a comparison of experimental and theoreticalβ +/(EC +β +) probability ratios, theQ EC value was deduced to be 3,450 ± 150 keV. The strength was determined for four 0+→1+ Gamow-Teller beta transitions and found to be quenched as compared to predictions of the single-particle shell model. For96Pd and94Ru the sources of this quenching are discussed. 相似文献
513.
W. Żmijewska 《Journal of Radioanalytical and Nuclear Chemistry》1980,58(1-2):367-371
A method of the determination of molybdenum in biological materials by neutron activation is described. The method is based
on the γ-spectrometric measurement of99mTc after radiochemical separation of the latter by substoichiometric extraction with tetraphenylarsonium chloride using rhenium
as inactive carrier. The method has been tested with reference materials. 相似文献
514.
P. Żenczykowski 《International Journal of Theoretical Physics》1990,29(12):1327-1334
It is pointed out that in the naive quark model the weak-interaction-induced parity-violating coupling of transverse photons to the nucleon does not vanish atq
2=0. The presence of this nonvanishing anomalous parity-violatingNN couplingg
ais a direct consequence of thecomposite nature of hadrons: gauge invariance requires the vanishing ofg
aonly if the nucleon can be described by a Dirac spinor depending on asingle spacetime point. Nonvanishing ofg
ain the quark model makes precise measurements of weak radiative hyperon decays particularly important.On leave of absence from the Department of Theoretical Physics, Institute of Nuclear Physics, Cracow, Poland. 相似文献
515.
Dietmar Heidrich Dietmar Volkmann Bronisz.xl;law Żurawski 《Chemical physics letters》1981,80(1):60-63
The deprotonation energy of a (H3Si)O-H group as a simplified structural element of silica gel and aluminosilicates is estimated from ab initio calculations on H2O, CH30H and SiH30H to be near 1475 kJ/mol. Results of the effect of Lewis acids on the Brønsted acidity of SiOH are given. 相似文献
516.
W. Żabiński I. Wacławska C. Paluszkiewicz 《Journal of Thermal Analysis and Calorimetry》1996,46(5):1437-1447
The thermal decomposition of vesuvianite was studied by means of thermal, FTIR and X-ray methods. It was found that two structural forms of vesuvianite, a high-temperature (disordered) and a low-temperature (ordered) one, differ distinctly in the mechanism of their decomposition (dehydroxylation). Dehydroxylation of low vesuvianites begins at lower temperatures (ca. 900°C), and the strong endothermic peak with maximum at ca. 1020°C is usually followed by an exothermic peak. Dehydroxylation of high vesuvianites begins at ca. 1000°C, and the OTA curve usually displays two endothermic peaks not followed by an exothermic effect. The crystallization products of vesuvianite are grossular, gehlenite and anorthite. Vesuvianite melts in the temperature range 1100–1200°C.The authors thank Mr. A. Gawel for kindly recording the X-ray powder diffractograms. This study was supported by KBN grant No 6 P201 018 04. 相似文献
517.
Heats of solution of acetonitrile, solvated or hydrated perchlorates, Mn(ClO4)2·6AN, Co(ClO4)2·6AN, Ni(ClO4)2·6AN, Cu(ClO4)2·4AN, Cu(ClO4)2·6H2O, Zn(ClO4)2·6AN, and Zn(ClO4)2·6H2O have been determined in NMF, DMF, DMA, and water. Complete or almost complete exchange of AN and water molecules in amides is inferred from the visible spectra determinations. The heats of transfer of perchlorate anion from water to DMA and NMF have been obtained from separately determined heats of solution of NaBPh4, AsPH4Cl·H2O, NaClO4, NaCl, and SiPh4 in the respective solvents. The heats of transfer of cations from water to amides have been determined from the above data and the heats of solvation of cations using literature data for the heats of hydration. 相似文献
518.
J. Żurakowska-Orszagh K. Mirowski H. Wilczura 《Journal of Thermal Analysis and Calorimetry》1981,21(1):27-34
The thermal properties of complexes of N-tert-butylacrylamide and N-tert-amylacrylamide with ZnCl2, ZnBr2, CdCl2 and CdBr2 have been studied in air and in argon by TG and DTA. The decomposition proceeds in two steps with evolution of simple, low molecular weight gaseous products. The use of various heating rates revealed an additional exothermic DTA peak for complexes with zinc and cadmium chlorides corresponding to a solid state polymerization reaction which was confirmed by IR spectral analysis. This effect was not observed for corresponding complexes of zinc and cadmium bromides, which show much lower thermal stability.
Zusammenfassung Die thermischen Eigenschaften der Komplexe von N-Tertbutylacrylamid und N-Tertamylacrylamid mit ZnCl2, ZnBr2, CdCl2 und CdBr2 wurden in Luft und in Argon durch TG und DTA studiert. Die Zersetzung verläuft in zwei Stufen unter Entwicklung einfacher gasförmiger Produkte niedriges Molekulargewichts. Der Einsatz verschiedener Aufheizgeschwindigkeiten zeigte für Komplexe mit Zink- und Cadmiumchloriden einen zusätzlichen DTA Peak, der Festphasen-Polymerisationsreaktion entsprechend, welche durch IR-Spektralanalyse bestätigt wurde. Dieser Effekt wurde bei den entsprechenden Komplexen der Zink- und Cadmiumbromide, welche eine viel geringere Thermostabilität besitzen, nicht beobachtet.
Résumé On a étudié, par TG et ATD, dans l'air et l'argon, les propriétés thermiques des complexes du N-tertbutyl-acrylamide et du N-tétramylacrylamide avec ZnCl2, ZnBr2, CdCl2 et CdBr2. La décomposition s'effectue en deux étapes, avec dégagement de produits gazeux simples de faible poids moléculaire. L'application de différentes vitesses de chauffage a révélé, pour les complexes des chlorures de zinc et de cadmium, un pic exothermique additionnel en ATD qui correspond à la réaction de polymérisation dans l'état solide et qui a été confirmé par spectrométrie infrarouge. On n'a pas observé cet effet dans le cas des complexes correspondants des bromures de zinc et cadmium dont la stabilité thermique est bien plus faible.
N- - N- ZnCl2, ZnBr2, CdCl2 CdBr2. , . . , . , .相似文献
519.
W. Żmijewska 《Journal of Radioanalytical and Nuclear Chemistry》1972,10(2):187-196
A method has been developed for the substoichiometric separation of Cr(VI) by extraction with tri-n-octylamine solution in
benzene from 0.1M H2SO4 solution. The method has been applied to the determination of chromium in silicon and aluminium by the neutron activation
method. 相似文献
520.
Metalloproteases utilize their active site divalent metal ions to generate a nucleophilic water/hydroxide. For methionine aminopeptidases (MetAPs), the exact location of this nucleophile, as well as of the substrate, with respect to the active site metal ion is unknown. In order to address this issue, we have examined the catalytically competent Fe(II)-loaded form of PfMetAP-II ([Fe(PfMetAP-II)]) in the absence and presence of both nitric oxide (NO) and the substrate-analogue inhibitor butaneboronic acid (BuBA) by kinetic and spectroscopic (EPR, UV-vis) methods. NO binds to [Fe(PfMetAP-II)] with a Kd of 200 microM forming an {FeNO}7 complex. UV-vis spectra of the resulting [Fe(PfMetAP-II)]-NO complex indicate that the Fe(II) ion is six coordinate. These data suggest that NO binding occurs without displacing the bound aquo/hydroxo moiety in [Fe(PfMetAP-II)]. On the basis of EPR spectra, the resulting Fe-NO complex is best described as NO- (S = 1) antiferromagnetically coupled to a high-spin Fe(III) ion (S = 5/2). The addition of BuBA to [Fe(PfMetAP-II)]-NO displaces the coordinated water molecule forming a six-coordinate adduct. EPR data also indicate that an interaction between the bound NO- and BuBA occurs forming a complex that mimics an intermediate step between the Michaelis complex and the tetrahedral transition-state. 相似文献