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81.
Mekenyan OG Dimitrov SD Pavlov TS Veith GD 《SAR and QSAR in environmental research》2005,16(1-2):103-133
This paper presents the framework of a QSAR-based decision support system which provides a rapid screening of potential hazards, classification of chemicals with respect to risk management thresholds, and estimation of missing data for the early stages of risk assessment. At the simplest level, the framework is designed to rank hundreds of chemicals according to their profile of persistence, bioaccumulation potential and toxicity often called the persistent organic pollutant (POP) profile or the PBT (persistent bioaccumulative toxicant) profile. The only input data are the chemical structure. The POPs framework enables decision makers to introduce the risk management thresholds used in the classification of chemicals under various authorities. Finally, the POPs framework advances hazard identification by integrating a metabolic simulator that generates metabolic map for each parent chemical. Both the parent chemicals and plausible metabolites are systematically evaluated for metabolic activation and POPs profile. 相似文献
82.
Preparation and Properties of Norbornyl Mercury Compounds Bis(1-norbornyl) and bis(2-norbornyl)mercury, 1- und 2-norbornylmercury chloride and 1-norbornylmercury i-butyl were synthesized and characterized by 13C-N.M.R. investigations and in case of bis(1-norbornyl) mercury also by the I.R. and mass spectrum. The 1J(199Hg? 13C) coupling constants of the 1-norbornyl compounds demonstrate the trans-influence of the norbornyl anion. 相似文献
83.
Structural models for glasses of the TeO2–MoO3 system are suggested. On the basis of X-ray and infrared spectral investigations, by comparing with known crystalline structures of TeO2, MoO3 and Te2MoO7(T2M), it is shown that the glasses from TeO2 to Te2MoO7 possess [TeO4] and [MoO5] groups as basic structural units. The latter are connected to form [Mo2O8] complexes. The glasses in the MoO3-rich compositional range are built up of [TeO3] and [MoO6] polyhedra. The glass-formation tendency is discussed in relation to the role of the free electron pair and the disruption of secondary and weak primary bonds in the crystals. 相似文献
84.
The kinetics of acetoxylation of cyclododecene and (E,E,E)-1,5,9-cyclododecatriene catalyzed by Pd(OAc)2 has been studied in glacial acetic acid solutions at 323–343 K and atmospheric pressure. The experimental data were described
by kinetic equations of the Michaelis-Menten type. 相似文献
85.
V. Dimitrov 《Physics of Particles and Nuclei Letters》2011,8(4):391-394
Initially, relational model of data has been specified by E. F. Codd with the naming conventions to the attributes called
“relationship”. It is something between relations and tables, i.e., between implementation and user view on data. In this
paper, ideas for “relationship” are formally specified in Z-notation. The last one is an ISO standard now. The purpose of this paper is to reinvestigate ideas behind the “relationships”
in a more formal way. This approach is useful for further research in extending relation model of data to capture multimedia
data and data streams, which are, usually, generated by different kinds of sensors. 相似文献
86.
The behavior of the Kozachenko–Leonenko estimates for the(differential) Shannon entropy is studied when the number of i.i.d. vector-valued observations tends to infinity. The asymptotic unbiasedness and L~2-consistency of the estimates are established. The conditions employed involve the analogues of the Hardy–Littlewood maximal function. It is shown that the results are valid in particular for the entropy estimation of any nondegenerate Gaussian vector. 相似文献
87.
Ivan E. Dimitrov Ravinder Reddy John S. Leigh 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2000,145(2):302
Intermolecular 129Xe–1H nuclear Overhauser effects and 129Xe longitudinal relaxation time measurements were used to demonstrate that the dipole–dipole coupling is the dominant relaxation mechanism for 129Xe in water, at room temperature. 129Xe–1H cross-relaxation rates were derived to be ςXeH 3.2 ± 0.3 × 10−3 s−1, independent of xenon pressure (in the range of 1–10 bar) and of the presence of oxygen. Corresponding xenon–proton internuclear distances were calculated to be 2.69 ± 0.12 Å. Using the magnitude of the dipole–dipole coupling and the spin density ratio between dissolved xenon and bulk water, it is estimated that 129Xe–1H spin polarization-induced nuclear Overhauser effects would yield little net proton signal enhancement in water. 相似文献
88.
The space and time change of the optical density of laser-produced microplasma is studied. A statistical model is proposed which allows its utilization for assessing plasma optical density at a constant, as well as at a changing laser radiation intensity. 相似文献
89.
The oxidation of metal sulphides and sulphide concentrates was studied by means of DTA, TG and DTG curves. The behaviour of
ZnS, CdS, GaS, Tl2S, Sb2S3 and Sb2S5 during thermal treatment in an oxidizing medium was investigated. The properties of these sulphides were compared and conclusions
were drawn about their probable oxidation reactions and the kind of end-products obtained. The characteristic temperatures
of the studied sulphides were determined on the basis of curves (DTA). The values obtained were used to compare the behaviour
of the sulphides during the oxidation process in a fluid bed. The results can be used to improve the technological and economic
indices in the industrial production of zinc.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
90.
Said El‐Kurdi Abdal‐Azim Al‐Terkawi Bernd M. Schmidt Anton Dimitrov Dr. Konrad Seppelt Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(2):595-599
WF6 reacts with phosphines R3P forming 1:1 compounds. With R=P(CH3)3 the coordination around the tungsten atom is capped trigonal prismatic, with R=P(CH3)2C6H5 the coordination is capped octahedral, as established by single‐crystal structure determinations: [(CH3)3P? WF6]: a=752.5(21), b=945.7(24), c=629.8(18) pm. β=110.36(13)°, space group Cm, Z=2; [(CH3)2(C6H5)P? WF6]: a=762.2(2), b=1123.5(2), c=2647.5(6) pm, space group Pbca, Z=8. [(CF3CH2)2N? WF5] reacts smoothly with P(C6H5)3 forming known P(C6H5)3(F)2 and [(CF3CH2)2N? WF4? P(C6H5)3], a stable, green, molecular species, identified among other methods with an crystal structure determination: a=914.9(1), b=956.0(1), c=1449.8(2) pm, α=7.642(4), β=81.648(3), γ=81.519°, space group P$\bar 1$ , Z=2. 相似文献