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11.
A sensitive, selective, precise and stability-indicating high-performance thin-layer chromatographic method of analysis of nevirapine both as a bulk drug and in formulations was developed and validated. The solvent system consisted of toluene-carbon tetrachloride-methanol-acetone-ammonia (3.5:3.5:2.0:1.0:0.05, v/v/v/v/v). Densitometric analysis of nevirapine was carried out in the absorbance mode at 289nm. This system was found to give compact spots for nevirapine (R(f) value of 0.44+/-0.02). Nevirapine was subjected to acid and alkali hydrolysis, oxidation, dry heat and wet heat treatment and photodegradation. The drug undergoes degradation under acidic, basic conditions and oxidation. Also the degraded products were well resolved from the pure drug with significantly different R(f) values. Linearity was found to be in the range of 30-1000ng/spot with significantly high value of correlation coefficient. The linear regression analysis data for the calibration plots showed good linear relationship with r(2)=0.998+/-0.002 in the working concentration range of 300ng/spot to 1000ng/spot. The mean value of slope and intercept were 0.073+/-0.005 and 36.78+/-1.50, respectively. The method was validated for precision, robustness and recovery. The limit of detection and quantitation were 5 and 10ng/spot, respectively. As the method could effectively separate the drug from its degradation products, it can be employed as a stability indicating one. Moreover, the proposed HPTLC method was utilized to investigate the kinetics of acid degradation process. Arrhenius plot was constructed and activation energy was calculated. 相似文献
12.
Hans-Achim Kaul Dieter Greissinger Michael Luksza Wolfgang Malisch 《Journal of organometallic chemistry》1982,228(2):C29-C35
The reaction of Cp(CO)2FeEMe2 (E As, Sb, Bi) with Me3P, Et3P, Me2PhP and (MeO)3P leads to a CO/R3P exchange and formation of the chiral derivatives Cp(CO)(R3P)FeEMe2. Cp(CO)[(MeO)3P]FeEMe2 rearranges already at room temperature to Cp(CO)[(Me3E]FeP(O)(OMe)2 which is transformed by (MeO)3P to Cp(CO)[(MeO)3P]FeP(O)(OMe)2. The high nucleophilicity of the new organometallic Lewis bases is established by the easy conversion of Cp(CO)(Me3P)FeSbMe2 to [Cp(CO)(Me3P)Fe(SbMe3)]I with MeI, or to [Cp(CO)(Me3P)FeSbMe2Fe(CO)LCp]Hal (L CO, Hal Cl; L Me3P, Hal Br) with Cp(CO)LFe-Hal, respectively. The new compounds are characterized by spectroscopy and elementary analyses. 相似文献
13.
I. A. Martynova D. M. Tsymbarenko A. A. Kamenev S. N. Mudretsova A. N. Streletsky A. L. Vasiliev N. P. Kuzmina A. R. Kaul 《Russian Chemical Bulletin》2013,62(6):1454-1458
A series of (Y(AcO)3·4H2O—Q—Solv) solutions (Q is monoethanolamine (MEA), diethanolamine (DEA), en, dien; Solv = MeOH, EtOH, PriOH, BuOH) was studied to choose the metal-organic precursor for surface smoothing treatment of metallic tapes by chemical deposition of nanocrystalline yttria films. Based on the results of viscosity, wetting angle, and thermal stability measurements, a solution (Y(AcO)3·4H2O—dien—PriOH) was proposed as a new metal-organic precursor. After chemical deposition of nanocrystalline yttria films about 300 nm thick on a Hastelloy C-276 metallic tape the surface roughness was reduced by a factor of 11 (from 9.0 to 0.8 nm on a surface area of 5×5 μm2). 相似文献
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V. K. Gupta S. K. Badval I. K. Daftari G. L. Kaul L. K. Mangotra N. K. Rao S. K. Sharma Gian Singh Y. Prakash 《Zeitschrift fur Physik C Particles and Fields》1981,10(1):29-36
The shower particle multiplicity (〈n s 〉) in thep-nucleus interactions for different targets, in the incident energy range of ~6–500 GeV has been studied. The variation of multiplicity parameters with target mass (A) or with number of interactions that the incident hadron suffers inside the nucleus (v A ) and with the changed particle multiplicity inp-p interactions (〈n ch〉) has been examined in the light of the various models of multiparticle production. The present analysis favours the hydrodynamical model though some other models can not be conclusively ruled out. 相似文献
17.
K. H. Althoff M. Gies O. Kaul K. Königsmann D. Menze W. Meyer T. Miczaika E. Roderburg W. Schwille 《Zeitschrift fur Physik C Particles and Fields》1979,1(3):257-258
We report the measurement of the differential cross section of the reaction γ +p→π0 +p at a photon energy of 1.4 GeV and pion c.m. angles between 60 and 175 degrees. The angular distribution confirms the simple quark model prediction of a pure magnetic excitation of theF 37 (1950) resonance. 相似文献
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19.
A. I. Abramovich O. Yu. Gorbenko A. R. Kaul L. I. Koroleva A. V. Michurin 《Physics of the Solid State》2004,46(9):1711-1716
Magnetic, elastic, magnetoelastic, transport, and magnetotransport properties of the Eu0.55Sr0.45MnO3 ceramics have been studied. A break was detected in the temperature dependence of electrical resistivity ρ(T) near the temperature of the magnetic phase transformation (41 K), with the material remaining an insulator down to the lowest measurement temperature reached (ρ=106 Ω cm at 4.2 K). In the interval 4.2≤T≤50 K, the isotherms of the magnetization, volume magnetostriction, and ρ were observed to undergo jumps at the critical field HC1, which decreases with increasing T. For 50≤T≤120 K, the jumps in the above curves persist, but the pattern of the curves changes and HC1 grows with increasing T. The magnetoresistance Δρ/ρ = (ρ H ?ρH=0)/ρ H is positive for H<HC1 and passes through a maximum at 41 K, where Δρ/ρ = 6%. For H>HC1, the magnetoresistance is negative, passes through a minimum near 41 K, and reaches a colossal value of 3×105 % at H=45 kOe. The volume magnetostriction is negative and attains a giant value of 4.5×10?4atH=45 kOe. The observed properties are assigned to the existence of three phases in Eu0.55Sr0.45MnO3, namely, a ferromagnetic (FM) phase, in which carriers are concentrated because of the gain in s-d exchange energy, and two antiferromagnetic (AFM) phases of the A and CE types. Their fractional volumes at low temperatures were estimated to be as follows: ~3% of the sample volume is occupied by the FM phase; ~67%, by the CE-type AFM phase; and ~30%, by the A-type AFM phase. 相似文献
20.
Phosphoric acid plant wastewater containing fluoride, phosphate and chemical oxygen demand etc., was treated using electrooxidation and electroflocculation methods. A maximum of 82% F- and 22.7% COD were removed using Ti/Pt(5c) under electrooxidative conditions. Electrooxidation with respect to F- removal is found mass-transfer limited, and removals below 5-6 mg/L F- are not achievable. Electroflocculation using Al anode resulted in better removal of F-, COD and PO4(3-). The various results obtained are discussed in this paper. 相似文献