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221.
The content of total polyphenols, flavonoids and coumarins in the aerial parts of pineapple weed (Chamomilla suaveolens (Pursh) Rydb.), growing wild in Estonia, was determined chromato-spectrophotometrically, and individual polyphenols were quantified using HPLC-DAD-MS/MS. The total content of polyphenols was rather similar in flowers (9.1-11.5%) and in whole aerial parts (8.4-10.9%) of pineapple weed. The upper one-third (1/3) and upper two-thirds (2/3) of the aerial parts contained more flavonoids (0.15 - 0.20%) than the flowers (0.12%). The content of coumarins showed no significant difference between the flowers and the upper 1/3 and 2/3 of the aerial parts. The main polyphenols in the flowers were dicaffeoylquinic acids (202-380 mkg/mL), chlorogenic acids (75-185 mkg/mL), and ferulic acid glycoside (61-124 mkg/mL). Also found were quercetin galactoside, apigenin acetylglucoside, malonylapigenin glucoside, as well as luteolin, quercetin and apigenin glycosides. 相似文献
222.
Hermi F. Brito Jukka Hassinen Jorma Hölsä Högne Jungner Taneli Laamanen Mika Lastusaari Marja Malkamäki Janne Niittykoski Pavel Novák Lucas C. V. Rodrigues 《Journal of Thermal Analysis and Calorimetry》2011,105(2):657-662
The details of the mechanism of persistent luminescence were probed by investigating the trap level structure of Sr2MgSi2O7:Eu2+,R3+ materials (R: Y, La-Lu, excluding Pm and Eu) with thermoluminescence (TL) measurements and Density Functional Theory (DFT)
calculations. The TL results indicated that the shallowest traps for each Sr2MgSi2O7:Eu2+,R3+ material above room temperature were always ca. 0.7 eV corresponding to a strong TL maximum at ca. 90 °C. This main trap
energy was only slightly modified by the different co-dopants, which, in contrast, had a significant effect on the depths
of the deeper traps. The combined results of the trap level energies obtained from the experimental data and DFT calculations
suggest that the main trap responsible for the persistent luminescence of the Sr2MgSi2O7:Eu2+,R3+ materials is created by charge compensation lattice defects, identified tentatively as oxygen vacancies, induced by the R3+ co-dopants. 相似文献
223.
Janne Gröhn 《Bulletin des Sciences Mathématiques》2011,(5):475
The iterative method of successive approximations, originally introduced by Émile Picard in 1890, is a basic tool for proving the existence of solutions of initial value problems regarding ordinary first order differential equations. In the present paper, it is shown that this method can be modified to get estimates for the growth of solutions of linear differential equations of the typef(k)+Ak−1(z)f(k−1)+?+A1(z)f′+A0(z)f=0 with analytic coefficients. A short comparison to the growth results in the literature, obtained by means of different methods, is also given. It turns out that many known results can be proved by applying Picard?s successive approximations in an effective way. Self-contained considerations are carried out in the complex plane and in the unit disc, and some remarks about solutions of real linear differential equations are made. 相似文献
224.
On a fixed Riemann surface (M 0, g 0) with N Euclidean ends and genus g, we show that, under a topological condition, the scattering matrix S V (λ) at frequency λ > 0 for the operator Δ+V determines the potential V if \({V\in C^{1,\alpha}(M_0)\cap e^{-\gamma d(\cdot,z_0)^j}L^\infty(M_0)}\) for all γ > 0 and for some \({j\in\{1,2\}}\) , where d(z, z 0) denotes the distance from z to a fixed point \({z_0\in M_0}\) . The topological condition is given by \({N\geq \max(2g+1,2)}\) for j = 1 and by N ≥ g + 1 if j = 2. In \({\mathbb {R}^2}\) this implies that the operator S V (λ) determines any C 1, α potential V such that \({V(z)=O(e^{-\gamma|z|^2})}\) for all γ > 0. 相似文献
225.
Hosseini M Grau JS Sørensen KK Søtofte I Tanner D Murray A Tønder JE 《Organic & biomolecular chemistry》2007,5(14):2207-2210
The pyrrolidine-2,4-diones have been identified as a convenient starting point for the synthesis of peptide analogues. Herein we describe an optimized two-step reductive amination procedure, which provides a small library of pyrrolidinone-containing dipeptide analogues in high yield and excellent diastereoselectivity. 相似文献
226.
Janne Kauhanen 《Journal of Mathematical Analysis and Applications》2006,315(2):656-665
Let f∈W1,1(Ω,Rn) be a homeomorphism of finite distortion K. It is known that if K1/(n−1)∈L1(Ω), then the Jacobian Jf of f is positive almost everywhere in Ω. We will show that this integrability assumption on K is sharp in any Orlicz-scale: if α is increasing function (satisfying minor technical assumptions) such that limt→∞α(t)=∞, then there exists f such that K1/(n−1)/α(K)∈L1(Ω) and Jf vanishes in a set of positive measure. 相似文献
227.
Abstract The epidithiopiperazinedione structure I, a common functionality in the natural products of the gliotoxin-sporidesmin class of compounds is believed to be responsible for the antiviral activity which this class possesses. 相似文献
228.
Dan Peters Anna-Britta Hrnfeldt Salo Gronowitz 《Journal of heterocyclic chemistry》1991,28(6):1613-1617
Some Pd-catalyzed coupling reactions have been evaluated for the synthesis of 5-substituted cytosines. A large number of 5-arylcytosines were prepared in good yields by using 2,4-O,N-bis-trimethylsilyl-5-iodocytosine with various aryl tin compounds. The use of trimethylsilyl groups proved to be essential for the reaction, attempted coupling of 5-iodocytosine and 2-trimethylstannylthiazole was not successful. One convenient alternative, which unfortunately was not successful, would have been to reverse the coupling functionalities and couple commercial arylhalides with 5-trimethylstannyl- or 5-tributylstannyl-derivatives or the corresponding 2,4-O,N-bis-trialkylsilylcytosines. 相似文献
229.
J. Salo R. Lappalainen A. Anttila 《Applied Physics A: Materials Science & Processing》1995,61(4):353-355
The carbon plasma ion energies produced by the pulsed filtered arc-discharge method have been measured as a function of the anode-cathode voltage. The energies were determined by using the electro-optical time-of-flight method. The highest anode-cathode voltage was 5 kV and yielded the energy of 140 eV for the plasma ions. In addition, it was demonstrated that a rather slight change of the parameters in the arc-discharge method has a strong effect on the plasma ion energies and the properties of the diamond-like coatings prepared. 相似文献
230.
Mikko Ritala Timo Asikainen Markku Leskel Janne Jokinen Reijo Lappalainen Mikko Utriainen Lauri Niinist Eero Ristolainen 《Applied Surface Science》1997,120(3-4):199-212
The reasons for the improvements gained by using intermediate zinc pulses in atomic layer epitaxy growth of TiN and NbN films were examined by a comprehensive characterization and comparison of films prepared from TiCl4 or NbCl5 and NH3 with and without zinc. The characterization techniques used comprise time-of-flight elastic recoil detection analysis, secondary ion mass spectrometry, Rutherford backscattering spectrometry, nuclear resonance broadening, proton backscattering spectrometry, deuteron induced reactions, proton induced X-ray emission, atomic force microscopy, scanning electron microscopy, X-ray diffraction, and Hall effect and reflectance measurements. The effect of zinc was found to be manifold: both compositional and structural changes were observed. In the case of TiN the major improvement gained by using zinc was significantly decreased oxygen contamination whereas a marked increase of grain size was the dominant effect observed with NbN. A clear correlation between the compositional and structural changes and the improvements of the electrical properties was established. 相似文献