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711.
712.
Izabela Agata Malinowska 《Monatshefte für Mathematik》2013,171(2):205-216
Berkovich investigated the following concept: a subgroup H of a finite group G is called an NR-subgroup (Normal Restriction) if whenever ${K \trianglelefteq H}$ , then ${K^G \cap H = K}$ , where K G is the normal closure of K in G. Bianchi, Gillio Berta Mauri, Herzog and Verardi proved a characterization of soluble T-groups by means of ${\mathcal{H}}$ -subgroups: a subgroup H of G is said to be an ${\mathcal{H}}$ -subgroup of G if ${H^g \cap N_G(H) \leq H}$ for all ${g \in G}$ . In this article we give new characterizations of finite soluble PST-groups in terms of NR-subgroups or ${\mathcal{H}}$ -subgroups. We will show that they are different from the ones given by Ballester-Bolinches, Esteban-Romero and Pedraza-Aguilera. Robinson established the structure of minimal non-PST-groups. We give the classification of groups all of whose second maximal subgroups (of even order) are soluble PST-groups. 相似文献
713.
Jacek Szczepkowski Patryk Jasik Anna Grochola Włodzimierz Jastrzȩbski Józef E. Sienkiewicz Paweł Kowalczyk 《The European physical journal. Special topics》2013,222(9):2329-2333
The 41Σ+ state of LiCs molecule is observed experimentally for the first time. The inverted perturbation approach (IPA) method is used to derive the potential energy curve of the state from the measured spectra. The experiment is accompanied by theoretical calculations of adiabatic potentials for excited states in LiCs including 41Σ+, performed with the MOLPRO program package. The irregular shape of the 41Σ+ state potential predicted by theory is confirmed in the experiment. 相似文献
714.
Mlynarski J Rakiel B Stodulski M Suszczyńska A Frelek J 《Chemistry (Weinheim an der Bergstrasse, Germany)》2006,12(31):8158-8167
The asymmetric aldol-Tishchenko reaction of aromatic aldehydes with aliphatic and aromatic ketones has been developed as an efficient strategy for the synthesis of anti-1,3-diols in good yield with high diastereocontrol and good levels of enantioselectivity. This domino-type reaction is catalyzed by a chiral ytterbium complex that promotes both the aldol reaction through enolization of the carbonyl compound and the Evans-Tishchenko reduction of the aldol intermediate. The stereochemistry of the resulting diols is also investigated and finally proved by using CD techniques. 相似文献
715.
Juskowiak B Galezowska E Zawadzka A Gluszynska A Takenaka S 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2006,64(4):835-843
Results of the steady-state fluorescence, anisotropy and FRET measurements of G-quadruplex formation in the presence of selected cations (Li(+), Na(+), K(+), NEt(4)(+) and Mg(2+)) are reported. Three different fluorescent oligonucleotides with human telomeric sequence labeled with fluorescein (FAM) and tetramethylrhodamine (TAMRA) were investigated: a dual-labeled 21-mer denoted as PSO (Potassium Sensing Oligonucleotide) and two 5'- and 3'- single-labeled probes, FAM-21 and 21-TAMRA, respectively. The fluorescence signal of FAM-21 increased significantly for all systems and the fluorescence enhancement was comparable in magnitude for monovalent cations but it was more pronounced for Mg(2+) cation. This phenomenon was attributed to the protolytic equilibria of FAM affected by the variation in ionic strength. On the other hand, fluorescence of TAMRA was enhanced selectively by Na(I) cation that was explained by the dequenching of TAMRA emission originated from the peculiarity of the basket-type structure of Na(I)-quadruplex. Anisotropy of FAM-21 (but not 21-TAMRA) appeared to be sensitive to the G-quadruplex formation, showing significant increase with an increase in cation concentration and indicating some restrictions in rotational depolarization of FAM. FRET experiments revealed that all tested cations caused quenching of FAM fluorescence in PSO, but only Na(+) and K(+) ions produced sensitized emission of TAMRA acceptor. Higher FRET efficiency observed in the presence of sodium ion was attributed to the specific spectral factor and steric interactions in the basket-type Na(I)-quadruplex. 相似文献
716.
Different authors investigated the effects of geometric and energetic heterogeneities on adsorption and on carbon characterization methods. In most theoretical studies carbon structure is modeled as parallel infinite graphite walls that form ideal slit-shaped pores of the fixed widths. In the literature there is the lack of systematic studies showing the influence of pore structural and Lennard-Jones (LJ) potential parameters on the pore-size distribution functions. Moreover, the parameters characterizing the properties of the adsorbed phase and the heterogeneity of the adsorbent surface should be taken into account. The Nguyen and Do method with proposed by us ASA algorithm, were utilized for the assessment of the porosity from the series of almost few thousands numerically generated local adsorption isotherms. The values of the mentioned-above parameters are varied over the wide range (ca. +/-20%) of the reference ones. Different types of the theoretical and experimental adsorption isotherms (nitrogen at 77 K) were taken into account as the global ones. They were related to the mechanism of the primary, secondary or mixed micropore filling. The variations in some above-mentioned parameters have significant effects only for PSDs (and for average pore widths) corresponding to the primary micropore filling mechanism. On the other hand, for the process of the secondary micropore filling, the influence of these parameters (without the BET coefficient for adsorption on a "flat" surface, c(s,B)) is rather insignificant. Nevertheless the differences between local and global adsorption isotherms (in the whole range of relative pressures) the absence of micropores having pore half width equal to ca. 1 nm on PSDs was observed for studied adsorbate-adsorbent systems with exceptions of the strictly microporous adsorbents and/or the low values of c(s,B). Comparison of the experimental data with the generated theoretical isosteric enthalpy of adsorption indicates that the phenomenal uptake observed from experiment can be explained in terms of the reasonable solid-fluid interaction parameters. Therefore, we varied the heterogeneity of the adsorbent surface via the strength and the range of the solid-fluid potential and the parameter c(s,B) in order to reproduce the experimental data of enthalpy of adsorption. Note that similar procedure was applied by Wang and Johnson to reproduce some hydrogen adsorption data measured for carbon nanofibres. The analysis of the obtained results shows that the selection of the values of the parameters of the intermolecular interactions and the quantities characterizing the properties of the adsorbed phase and the heterogeneity of the adsorbent walls for molecular simulations should be made with care and the influence of possible errors should be considered. 相似文献
717.
The long range potential of the B 1Pi state in NaRb has been investigated by observation of rovibrational levels that it supports, including the high lying ones, with the technique of polarization labeling spectroscopy. This has allowed us to characterize the potential energy curve up to 1.9 cm(-1) from the dissociation limit. The highest observed rovibrational level v=49, J=10 has the outer turning point at R=16.48 A. 相似文献
718.
Michalska A 《Analytical and bioanalytical chemistry》2006,384(2):391-406
All-solid-state ion-selective electrodes that use a conducting polymer as the ion-to-electron transducer have emerged as one
of the most promising classes of all-solid-state potentiometric sensors in recent years. This is largely because it has many
analytical advantages, including high response stability, which is unique in the field of internal-solution-free ion-selective
electrodes. This paper reviews the considerable progress that has been made in this area of sensing in recent years, in terms
of detection limits, selectivity coefficients and novel construction methods. 相似文献
719.
Agata Siwek Monika Wujec Maria Dobosz Irena Wawrzycka‐Gorczyca 《Heteroatom Chemistry》2010,21(7):521-532
On a four series of 1‐azolil‐4‐aryl/alkyl‐thiosemicabazides, a study on the influence of azole moiety on the capability for intramolecular cyclization and its direction was carried out. It was found that for 4‐aryl/alkyl‐thiosemicabazides with triazole, imidazole, or pyrrole moiety at N‐1 nitrogen atom possible products were only s‐triazoles, both in alkaline and acidic medium. Successful dehydrocyclization of 1‐azolil‐4‐aryl/alkyl‐thiosemicarbazides leading to a thiadiazole has been documented only for a series of 1‐(4‐methyl‐1,2,3‐thiadiazol‐5‐yl‐carbonyl)‐4‐aryl/alkyl‐thiosemicarbazides. It can be speculative that the determination of pKa value of oxygen atom of 1‐azolil‐4‐aryl/alkyl‐thiosemicarbazide can be a very valuable parameter in the prediction of the possibility of dehydrocyclization to form thiadiazole. © 2010 Wiley Periodicals, Inc. Heteroatom Chem 21:521–532, 2010; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.20643 相似文献
720.