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891.
O. Schmitz-Dumont H. Fendel M. Hassanein Helga Weissenfeld 《Monatshefte für Chemie / Chemical Monthly》1966,97(6):1660-1695
Zusammenfassung Um die Beziehungen zwischen der Lichtabsorption des zweiwertigen Kupfers nach isomorphem Einbau in ein oxidisches Wirtsgitter und dessen Konstitution aufzufinden, wurde Cu2+ in oktaedrischer (Cu
x
Mg
1–x
TiO3, Cu
x
Cd
1–x
TiO3, Cu
x
Mg
1–x
CaSiO4, Cu
x
Mg
1–x
CaGeO4, Cu
x
Mg
2–x
SiO4, Cu
x
Mg
2–x
GeO4) und tetraedrischer Koordination (Cu
x
Zn2–x
SiO4, Cu
x
Mg
1–x
Cr2O4) spektralphotometrisch untersucht. Die Farbkurven besitzen mindestens 2 Absorptionsbanden (Kristallfeldbanden) im längerwelligen und eine oft gut ausgeprägte Elektronenübergangsbande (charge transfer) im kürzerwelligen Spektralbereich. In einigen Fällen ist noch eine zweite Elektronenübergangsbande als Schulter zu erkennen. Es wurden auch Cu-haltige 2,3- und 2,4-Spinelle spektralphotometrisch untersucht (Cu
x
Mg
1–x
Al2O4, Cu
x
Mg
1–x
Ga2O4, Cu
x
Cd
y
Zn
1–x–y
Al2O4, Cu
x
Mg
2–x
SnO4, Cu
x
Mg
2–x
TiO4, Cu
x
Zn
1–x
MgTiO4, Cu
x
Mg
1–x
Cd
y
TiO4). Es zeigte sich, daß Cu2+ immer auf Tetraeder- und Oktaederlücken verteilt ist. Eine Aufweitung des Wirtsgitters durch isomorphen Einbau größerer Kationen bewirkt nicht immer eine IR-Verschiebung der Banden, sondern in einigen Fällen (Spinellphasen) auch eine UV-Verschiebung. Eine Sonderstellung nimmt das ägyptisch-Blau CuCaSi4O10 ein, da hier das Cu2+ von 4 O2– in planarer Anordnung umgeben ist. Die Farbkurve weist 3 Maxima auf im Einklang mit der Kristallfeldtheorie.
Mit 20 Abbildungen 相似文献
In order to find out relations between the lightabsorption of bivalent copper isomorphously incorporated into an oxidic host lattice and the constitution of this lattice, the spectrum of Cu2+ has been investigated in octahedral (Cu x Mg1–x TiO3, Cu x Cd 1–x TiO3, Cu x Mg 1–x CaSiO4, Cu x Mg 1–x CaGeO4, Cu x Mg 2–x SiO4, Cu x Mg 2–x GeO4) and tetrahedral coordination (Cu x Zn 2–x SiO4, Cu x Mg 1–x Cr2O4). The colour curves show at least 2 absorption bands within the region of longer wave length and a charge transfer band often well developed in the range of shorter wavelength. In some cases also a second charge transfer band becomes conspicuous as a shoulder. Copper containing 2,3- and 2,4-spinels have been also investigated (Cu x Mg 1–x Al2O4, Cu x Mg 1–x Ga2O4, Cu x Cd y Zn 1–x–y Al2O4, Cu x Mg 2–x SnO4, Cu x Mg 2–x TiO4, Cu x Zn 1–x MgTiO4, Cu x Mg 1–x Cd y Zn 1–y TiO4). From the colour curve one can infer that Cu2+ occupies in the spinels always tetrahedral as well as octahedral interstices. A widening of the lattice does not effect always a shifting of the absorption bands towards IR but in some cases (spinel phases) also the inverse shifting will occur. An exceptional case represents the egyptian blue CuCaSi4O10 since in this lattice the Cu2+ are surrounded by four O2– in a coplanar arrangement. The colour curve shows three absorption bands in agreement with the crystal field theory.
Mit 20 Abbildungen 相似文献
892.
The solubility of precipitated Cd(OH)2 was determined at 25°C in 1 M NaClO4, as a function of pH and of the ammonia content of the solutions. Formation constants were obtained for the following hydroxo, ammine and hydroxo-ammine complexes: CdOH+, Cd(OH)2, Cd(OH), CdNH, Cd(NH3), Cd(NH3), Cd(NH3) and Cd(OH)2NH3. The solubility product of the hydroxide was also calculated. The presence of polynuclear species was investigated by titrimetric determinations of the hydrogen ion concentration at constant metal concentration. 相似文献
893.
Using a new mathematical treatment, the nature and stability constants of the simple and mixed complex-species of copper(II) with hydroxyde and ammonia as ligands have been determined. The solubility curves of CuO in heterogeneous equilibrium have been identified in function of pH only and in function of pH and pNH3tot at 25° and unit ionic strength (NaClO4). The predominent species in the relatively dilute system limited by the ionic strength are [Cu2+], [Cu(OH)2], [Cu(OH)], [Cu(OH)], [Cu(NH3)], [Cu(NH3)], [Cu(NH3)], [Cu(NH3) (OH)+], [Cu(NH3)3(OH)+] and [Cu(NH3)2(OH)2]. 相似文献
894.
James O. Jensen 《Journal of Molecular Structure》2004,686(1-3):165-172
The normal mode frequencies and corresponding vibrational assignments of phosphirane in are examined theoretically using the GAUSSIAN 98 set of quantum chemistry codes. All normal modes were successfully assigned to one of nine types of motion (C–C stretch, P–C stretch C–H stretch, P–H stretch, CH2 scissors, CH2 wag, CH2 rock, CH2 twist, and P–H wag) predicted by a group theoretical analysis. Comparing the vibrational frequencies with IR and Raman spectra available in the literature, a set of scaling factors are derived. Predicted infrared and Raman intensities are reported. 相似文献
895.
C. Kelbch R. Koch S. Hagmann K. Ullmann H. Schmidt-Böcking C. O. Reinhold D. R. Schultz R. E. Olson G. Kraft 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1992,22(4):713-721
Double differential cross sections for the emission of Delta-electrons have been measured in fast uranium-rare gas collisions. The well-known Binary Encounter peak reveals unexpected structures for certain observation angles and its intensity increases towards smaller angles, which is in contradiction to results and scaling laws obtained by experiments with light ion impact. The observed dependencies are fairly well described by recent calculations in the framework of IA and CTMC. From systematic experimental as well as theoretical studies we can derive that the potential of the partially stripped projectile ion gives rise to rainbow and glory scattering of the target electron in the field of the projectile. The rainbow scattering is observed in the laboratory frame as pronounced interference structures, whereas the glory scattering is responsible for the steep increase of the cross sections for binary-encounter electrons towards small laboratory ejection angles. The observed effects have a dramatic influence on the commonq 2 scaling laws derived from experiments with light ions. Furthermore, since the binary-encounter electrons ejected at forward angles have approximately twice the projectile velocity, these new phenomena have an important influence on the electronic stopping power of heavy ions and therefore have to be taken into account for the investigation of radiation damage by these ions e.g. in biological matter. 相似文献
896.
T. P. Fischer S. Shuttleworth P. A. O’Day 《Analytical and bioanalytical chemistry》1998,362(5):457-464
The accurate measurement of ultra-trace concentrations of rare metals and platinum group elements in volcanic fluids is complicated by interferences, complex matrices, and preferential element partitioning. We analyzed condensed, high-temperature magmatic fluids collected from Kudryavy volcano (Kurile Islands, Russia) for Be, B, Rb, Sr, Mo, Ru, Rh, Pd, Cd, W, Re, Pt, Pb, Bi, and U using ICP-MS. The samples had three different matrices: 5 mol L–1 sodium hydroxide (NaOH, pH = 11), gas condensates of sulfuric acid (H2SO4, pH = 0), and solid elemental sulfur. Interferences and suppression/enhancement effects were investigated using standards in concentrated NaOH and H2SO4 solutions to determine adequate dilution for sample analyses, which then required very low levels of element detection (< 1 μg L–1 for most elements). Depending on the field sampling technique of volcanic gas vents, our results show significant differences in concentrations of some trace elements due to the precipitation of solid sulfur during gas condensation and variations in element volatility as a function of temperature. 相似文献
897.
O. V. Sizova A. I. Panin V. I. Baranovskii N. V. Ivanova 《Journal of Structural Chemistry》1996,37(2):181-191
Semiempirical INDO-E/S+RCIP calculations of the electronic structures of the ground and excited states of the pyrazine (pz)
molecule and [Ru(NH3)5pz]q (q=+1, +2, +3) complexes were performed to analyze the dependence of the calculation results on the active MO space and configuration
basis set. Recommendations for the construction of the {Фk} basis sets and formation of the {ϕk} sets are given.
St. Petersburg State University. Translated fromZhurnal Struktumoi Khimii, Vol. 37, No. 2, pp. 206–219, March–April, 1996.
Translated by I. Izvekova 相似文献
898.
5-Aminolevulinic acid (ALA)-supported fluorescence endoscopy of the urinary bladder results in a detection rate of bladder cancer superior to that of white light endoscopy. The different accumulation of the metabolite protoporphyrin IX (PPIX) in tumor cells after ALA instillation is poorly understood; however, it is crucial to optimize diagnosis and potential phototherapy. For systematic analysis of cell-type specific PPIX accumulation and metabolism two human bladder carcinoma cell lines (RT4 and J82), a normal urothelial cell line (UROtsa), and a fibroblast cell line (N1) were chosen, and grown in two different growth states to model important tissue components of the urinary bladder, i.e. tumor, normal epithelium and stroma. To quantitate PPIX content, fluorescence intensities measured by flow cytometry were matched with cellular PPIX extraction values, and related to relative ferrochelatase activity, cellular iron content, number of transferrin receptors per cell and porphobilinogen deaminase (PBGD) activity. For in vitro experiments, the initial correlation of relative flow cytometric and spectrometric measurements of PPIX provides a calibration curve for consequent flow cytometric PPIX quantification. Lower fluorescence of normal cells could be explained by significant differences of ferrochelatase activity and iron content in comparison to tumor cells. However, the content of iron was not related to transferrin receptor content. PBGD activity seemed to play a minor role for the differential accumulation of PPIX in urothelial cells. In conclusion, the in vitro culture of urothelial cells and fibroblasts indicates that the most important metabolic step for PPIX accumulation in the urinary bladder is the transition from PPIX to heme. Further investigation of PPIX metabolism does support the validation of photodynamic diagnosis, and might also lead the way to a highly specific tumor related molecule. 相似文献
899.
Gaile A. A. Zalishchevskii G. D. Semenov L. V. Khadartsev A. Ch. Varshavskii O. M. Fedyanin N. P. 《Russian Journal of Applied Chemistry》2004,77(4):566-570
Five-step countercurrent extraction of aromatic hydrocarbons from hydrofined diesel fraction with the 2-methoxyethanol-water-pentane extraction system was studied. The process was performed on a rotary-disk extractor. 相似文献
900.
Adsorption of formaldehyde from an aqueous medium on acid-treated clayey minerals was studied under conditions of natural convection and under stirring of the solution. 相似文献