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651.
652.
Lead oxide hydrate mentioned in the earlier literature with several formulas between PbO · H2O and PbO · 0.33 H2O has been synthesized and investigated by high resolution X-ray powder methods, thermogravimetry and infrared spectroscopy. The unit cell was found from 62 powder reflections to be tetragonal with a = 8.009 ± 0.003 Å, c = 9.312 ± 0.005 Å, Z = 12 [PbO · 0.33 H2O]. These data were confirmed by WEISSENBERG and Precession photographs of single crystals grown as a corrosion product on metallic lead. The space group is D–P4/mnc or C–P4 nc. Thermogravimetric measurements, corrected for a slight content of superficially bound carbon dioxide detected by infrared spectroscopy, lead to the most probable formula 3 PbO · H2O or PbO · 0.33 H2O. As infrared spectra show the presence of a HOH deformation vibration, the compound is considered to be an oxide hydrate and not an oxide hydroxide of lead. 相似文献
653.
Trofimov B. A. Malysheva S. F. Gusarova N. K. Tatarinova A. A. Henkelmann J. 《Russian Journal of Organic Chemistry》2003,39(9):1356-1357
Russian Journal of Organic Chemistry - 相似文献
654.
Frogs are known to obtain some of their nutrients (e.g., glucose and sodium) through their skin. However, no studies have been made of the possible absorption of transition metals, which exist in most river water at low-ppb (w/w) levels. Therefore, this research was undertaken to evaluate the use of ion chromatography for such an investigation. Solutions of copper and zinc (20 ppb in each) were chosen for use in a small-scale screening study. Ten live frogs were each placed in individual baths for approximately 50 h. Of interest were the net changes in the concentrations of the metals. These differences were the result of any absorption and/or excretion processes that took place. A Dionex IonPac CS5 column was used to analyze this simulated river water, both before and after frogs had been placed in the solution. Included in this paper are: (1) methodology and calculation formulas; (2) precautions needed to ensure sample integrity; (3) statistical analyses, which indicated that ion chromatography is an accurate, precise technique for quantifying Cu and Zn in these samples; and (4) screening-study results, which were used to test the null hypothesis that frogs do not absorb copper and zinc either onto or through their skin. 相似文献
655.
An immobiline DryStrip application method enabling high-capacity two-dimensional gel electrophoresis 总被引:5,自引:0,他引:5
Sabounchi-Schütt F Aström J Olsson I Eklund A Grunewald J Bjellqvist B 《Electrophoresis》2000,21(17):3649-3656
In the field of proteomics the need to detect low-abundance cellular components, such as regulatory proteins, is of critical importance. Two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) is one of the most commonly used separation tools for these biological investigations. In this paper we report an alternative micropreparative 2-D PAGE sample application method, called the "paper bridge loading" method. This method makes it possible to apply a larger sample volume to commercially available immobilized pH gradient (IPG) strips. The Vh products required for focusing are only marginally longer than those used in analytical experiments. The method was compared to traditional cup loading and in-gel rehydration. With 18 cm long narrow-range Immobiline DryStrip pH 4.5-5.5, the "paper bridge" method allowed the application of 10 mg human plasma proteins compared to 3 mg with traditional loading methods. The corresponding figures using Escherichia coli sample was found to be 6 mg and less than 2 mg, respectively. The paper bridge method also showed the best results in terms of spot resolution and separation of high molecular weight proteins. 相似文献
656.
657.
658.
659.
Zusammenfassung Eine einfache Methode zur Bestimmung von Acetessigester (I) und -Aceto--butyrolacton (II) nebeneinander beruht auf der sauren Hydrolyse, bei der aus I Aceton und CO2, aus II ebenfalls CO2 sowie Acetopropanol gebildet werden. Der Gehalt an I ergibt sich aus der Bestimmung von Aceton, die maßanalytisch mit Hilfe von Hydroxylaminhydrochlorid durchgeführt wird und für den durch Acetopropanol verursachten geringen Fehler korrigiert werden muß. Durch gravimetrische Bestimmung des CO2 ergibt sich die Summe I+II und aus der Differenz der Gehalt an II.
Summary A simple procedure for the determination of ethyl acetoacetate (I) and -aceto--butyrolactone (II) in presence of each other is based on hydrolysis in acid medium, whereby I yields acetone and CO2, II acetopropanol and CO2. The amount of I results from the determination of acetone performed volumetrically by means of hydroxylamine hydrochloride, a minor correction being required for the slight error caused by acetopropanol. CO2, corresponding to the sum I+II, is determined gravimetrically. The amount of II is calculated from the difference.相似文献
660.
A technique for following the hydrolysis of pyromellitic acid dianhydride (PMDA) by differential thermal analysis (DTA) is described. On exposure of PMDA to moisture, an endothennic peak is initiated between 190 and 200 degrees . As the degree of hydrolysis increases, this peak becomes more intense and shifts to higher temperatures. The formation of pyromellitic acid (PMA) during the hydrolysis of PMDA can be determined qualitatively by DTA. 相似文献