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951.
R. Stahlberg F. Steglich und M. Zieger 《Fresenius' Journal of Analytical Chemistry》1981,306(5):365-371
Zusammenfassung Die Charakterisierung von Isolaten differenziert behandelter Stähle erfordert die schnelle und genaue Bestimmung von Haupt- und Nebenbestandteilen aus Einwaagen im Milligrammbereich. Mit der Atomabsorptionsspektroskopie wurden die Elemente Fe (40–95 m-%) sowie Cr, Cu, Mn und Ni (0,05–10 m-%) aus einer Lösung (50–100 ml) durch Eichung mit geeigneten Standardstählen bestimmt.Die statistische Bewertung der Eisenbestimmung erfolgte am Beispiel der Analyse von Standardstählen und konkreten FexC-Isolaten. Die Ergebnisse wurden mit der klassisch-chemischen Isolatanalyse verglichen. Es wurden Reproduzierbarkeiten von s
r0,01 bei garantierter Richtigkeit im Konfidenzintervall erreicht. Voraussetzung dafür ist die Messung auf Fe-Linien geringerer Empfindlichkeit (373,7 nm bzw. 358,1 nm), wodurch weitere Verdünnungsschritte vermieden und das Signal-Rausch-Verhältnis verbessert werden.Bei der Cr-Bestimmung muß die spektrale Reinheit der Hohlkathodenlampe garantiert werden. Es wurde gezeigt, daß deutliche Mehrbefunde bei Lampen mit eisenhaltigem Trägermaterial bei Spaltbreiten > 0,2 nm und Messung auf
Cr=357,9 nm in Abhängigkeit vom Cr-Fe-Verhältnis auftreten. Als Ursache dafür wurde eine absorbierende Fe-Linie (358,1 nm) innerhalb der spektralen Bandbreite nachgewiesen.
On the accuracy of sequential determination of elements by AAS in electrochemically isolated structural constituents of differently treated steels
Summary The characterization of residues of differently treated steels requires the rapid and precise determination of principal and secondary components from mg sample weights. The elements Fe (40–95%-wt) and Cr, Cu, Mn, Ni (0.05–10% wt) were determined from one solution (50–100 ml) with calibration of suitable standard reference materials by atomic absorption spectroscopy.Precision and accuracy of the Fe-determination were studied at SRM and concrete FexC-residues and by comparison with classical chemical analysis. The precision was 1% with a guaranteed accuracy in the confidence interval. This was attained by using Fe-lines with lower sensitivity (373.7 nm or 358.1 nm) to eliminate the dilution and to increase the signal-to-noise ratio.For the determination of chromium, it is necessary to guarantee the spectral purity of the used hollow cathode lamp. It was shown that the Cr-response was too high in dependence on the Cr-Fe-ratio when using a hollow cathode lamp with ferruginous cathode material, a spectral bandpass of > 0.2 nm and the Cr-line Cr=357.9 nm. This was caused by an absorbing Feline (358.1 nm) in the used spectral bandpass.相似文献
952.
H. J. Rath 《Fresenius' Journal of Analytical Chemistry》1980,302(4):275-277
Zusammenfassung Die Metalle Chrom, Kupfer, Eisen und Nickel werden in reinem Boroxid mittels Atomabsorptionsspektroskopie erfaßt und kalibriert. Dazu wird B2O3 in verdünnter Salzsäure gelöst und die Metalle direkt analysiert. Die Nachweisgrenzen liegen zwischen 0,005 und 0,01 g/ml für diese Metalle. Bei den Messungen wurde eine systematische Signaldepression der Extinktionswerte festgestellt. Die Beeinflussung durch verschiedene B2O3-Konzentrationen wird diskutiert.
Determination of traces of Cr, Cu, Fe, Ni in boron oxide with atomic absorption spectroscopy
Summary The metals Cr, Cu, Fe and Ni are determined and calibrated in pure B2O3 with atomic absorption spectroscopy. B2O3 is dissolved in low-concentrated hydrochloric acid and the metals are analyzed directly. The detection limits are found to be in the range of 0.005 to 0.01 g/ml of these metals. The measurements showed a systematic signal depression of the absorbance values. The influence of different B2O3 concentrations is discussed.相似文献
953.
Zusammenfassung Das Verteilungsverhalten der oben genannten Di(trifluroäthyl)dithiocarbamato-Chelate zwischen wäßrigen Lösungen und Chloroform wird untersucht. Eine Anwendung zur gleichzeitigen gaschromatographischen Bestimmung von Blei und Wismut im ppm-Bereich (0,2–3 ppm) nach Ausschütteln aus wäßrigen Lösungen wird beschrieben (Säule: 5 % GE SE50 auf Gas Chrom Q; 180–240° C; 4°/min; Einspritzblock: 240° C).
Gas-chromatographic elemental analysis via di(trifluoroethyl)dithiocarbamatochelatesIV. Partition of the Di(trifluoroethyl)dithiocarbamates of Cu(II), Ni(II), Co(III), Fe(III), Bi(III), Pb(II) and Sb(III) between Aqueous Solutions and Chloroform-Extractive Simultaneous Determination of Lead and Bismuth by GLC
Summary The solvent extraction of the above di(trifluoroethyl)dithiocarbamatochelates with chloroform is investigated. An application for the simultaneous gas-chromatographic determination 0.2–3 ppm of lead and bismuth after extraction out of aqueous solutions is reported (column: 5% GE SE 50 on Gas Chrom Q; 180–240° C; 4°/min; injection block: 242°C).
Die Untersuchungen wurden in dankenswerter Weise durch Sachmittel der Deutschen Forschungsgemeinschaft und des Verbandes der Chemischen Industrie unterstützt. 相似文献
954.
A. Kaddouri R. Del Rosso C. Mazzocchia D. Fumagalli 《Journal of Thermal Analysis and Calorimetry》2001,63(1):267-277
Isothermal reduction under hydrogen of polymorphic NiMoO4 system has beenstudied at different temperatures using thermogravimetry. Evidences found by TG (oxygen depletion rate) have shown a dependence on lattice oxygen mobility and source due to the crystal structure and temperature.Relative to the undoped NiMoO4 phases, it has been found that the presence of K2O, CaO and P2O5 promoters simultaneously affects both the reduction rate and the oxygen source.Monolayer lattice oxygen mobility of undoped and doped NiMoO4 material was investigated by oxydehydrogenation of light alkanes performed by using a periodic flow micro-reactor. The alkane activity has been found to be linked to the reduction behaviour of the different undoped and doped NiMoO4 phases.This revised version was published online in November 2005 with corrections to the Cover Date. 相似文献
955.
首次采用催化气相沉积法(CVD),以异丙醇为溶剂将催化剂[Ni(NO3)2·6H2O]有效地分散在PAN-ACF较大的微孔上,使其成为积炭的活性位,从而将ACF的孔径调控在分子筛孔径效应范围内.以液氮为吸附质,测定了样品吸附等温线,采用H-K及DFT法计算孔结构,用XRD及SEM表征ACF的显微织构,并对该沉积过程进行了解释. 相似文献
956.
C.Otero Aren M. Pearroya Mentruit A. J. Lpez Lpez J. B. Parra 《Colloids and surfaces. A, Physicochemical and engineering aspects》2001,180(3):11725-258
The oxide spinel NiAl2O4 and spinel-type solid solutions Al2O3–NiAl2O4 (at Ni/Al=1:4, and Ni/Al=1:8) were prepared by controlled hydrolysis of mixed metal alkoxides, followed by calcination of the resulting gels. Powder X-ray diffraction showed that all samples prepared were single phase cubic materials having the spinel-type structure. The cubic lattice parameter, ao, was found to decrease gradually with increasing aluminium content of the mixed metal oxides. The specific surface area (determined by nitrogen adsorption at 77 K) was found to be in the range of 200–300 m2 g−1. The materials were found to be basically mesoporous, the most frequent pore radius being in the range 3.2–6.4 nm. IR spectroscopy of CO adsorbed at liquid nitrogen temperature gave a main band at 2186–2195 cm−1, which was assigned to the C---O stretching vibration of surface Al3+CO adducts where coordinatively unsaturated Al3+ ions act as Lewis acid centres. 相似文献
957.
Li Guang-She Li Li-Ping R. L. SmithJr. H. Inomata 《Journal of Molecular Structure》2001,560(1-3):87-93
The structural development of the NiFe2O4 nanocrystals dispersed in a silica matrix was followed by IR and EPR spectroscopies of the dried gel 10NiO–10Fe2O3–90SiO2 after heat treatment. The dried gel obtained at 200°C was amorphous, in which Fe3+ and Ni2+ ions were distributed in the pores of silica matrix. When the dried gel was heat treated at 400°C, NiFe2O4 clusters were partially formed, showing an enhanced interaction with the silica matrix. NiFe2O4 clusters were completely formed in silica matrix when the heat treatment was increased to 600°C, at which the interactions between the clusters and silica matrix reached a maximum. The formation reaction of NiFe2O4 clusters was accompanied by a rearrangement of the silica matrix network. Further increase of the heat treatment temperature to 800°C led to superparamagnetic single domain NiFe2O4 nanocrystals (ca. 4 nm) dispersed in the silica matrix with the elimination of the interactions between magnetic nanocrystals and silica matrix. 相似文献
958.
人工神经网络用于光度法同时测定铜钴镍 总被引:14,自引:0,他引:14
本文采用PAR-Cu,Co,Ni显色体系,应用人工神经网络原理,以Levenberg-MarguardtBP算法,对紫外吸收光谱严重重叠的三组分金属配合物体系进行含量测定。在452-552nm的范围内,以14个特征波长处的吸收值作为网络特征参数,并通过正交设计安排样本。网络仅训练781次即可达到要求,Cu,Co,Ni三者的平均回收率分别为99.99%,99.97%,测定结果的相对标准偏差分别为0.1%,0.2%,0.1%。实验表明,该方法与现有的算法相比具有训练速度快,预测结果准确度高等特点。该方法和光度法结合有望成为多组分分析的有效方法之一。 相似文献
959.
8-羟基喹啉(HQ)是在化学分析中常用的试剂, 它与铝离子形成的配合物(AlQ3)也是目前有机电致发光领域最引人注目的明星分子. 在化学工业中, 8-羟基喹啉是有效的稀土及过渡金属的萃取剂, 它同中心离子的配合强度随条件改变亦有很大变化. 我们在钇和镍离子共同存在的条件下得到了标题化合物, 并测得其单晶结构. 相似文献
960.
FANRui-qing ZHUDong-sheng MUYing LIGuang-hua SUQing NIJian-guo FENGShou-hua 《高等学校化学研究》2005,21(4):496-500
In the past decade, the imino-complexes based on late transition metal have received significantly increasing attention for their excellent performance in the olefin polymerization area since Brookhart et al. demonstrated that the Ni( Ⅱ ) complexes incorporating with sterically hindered α-diimine ligands could be used in the polymerization of ethylene to form high molecular weight polymers. 相似文献