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101.
Kamali Saeed Häggström Lennart Ronneteg Sabina Berger Rolf 《Hyperfine Interactions》2004,156(1-4):315-319
Hyperfine Interactions - The quasi two-dimensional antiferromagnetic compound TlCo2Se2 has been studied by 57Fe Mössbauer spectroscopy. Small single crystals have been made with 2% Fe doping.... 相似文献
102.
Francesco Altomare Sabina Milella Graziana Musceo 《Journal of Evolution Equations》2011,11(4):771-792
Of concern are multiplicative perturbations of the Laplacian acting on weighted spaces of continuous functions on
\mathbbRN, N 3 1{{\mathbb{R}}^{N},\; N\geq1} . It is proved that such differential operators, defined on their maximal domains, are pre-generators of positive quasicontractive
C
0-semigroups of operators that fulfill the Feller property. Accordingly, these semigroups are associated with a suitable probability
transition function and hence with a Markov process on
\mathbbRN{{\mathbb{R}}^{N}} . An approximation formula for these semigroups is also stated in terms of iterates of integral operators that generalize
the classical Gauss-Weierstrass operators. Some applications of such approximation formula are finally shown concerning both
the semigroups and the associated Markov processes. 相似文献
103.
The dissociation constants of rutin in aqueous-methanol medium (6040 v/v), the values of which are pK1=–2.92±0.06, pK2=6.72±0.11, pK3=8.26±0.05, pK4=12.57±0.09, were estimated by using the spectrophotometric method. They were ascribed to the dissociation of protonated oxygen atom at position 1 and then to hydroxyl groups at positions 7, 4', 5, respectively. Resonance structures of H3L– ion of rutin were suggested and, by using them, the greater dissociability of the hydroxyl group at position 7 in relation to the –OH group at position 4' was explained. 相似文献
104.
Tubaro F Barbangelo F Toniolo R Di Narda F Susmel S Bontempelli G 《Annali di chimica》2002,92(3):289-299
The release of heavy metals from uncovered and nickel-covered brass pumps has been evaluated by ICP-MS analysis in both simple ultrapure water and 3% acetic acid solution (mimic of neutral and acid edible liquids, respectively), following a procedure similar to that recommended by the National Sanitation Foundation (NSF) International, Test Procedure P203. The results found highlight that the main release regards zinc, copper and lead, i.e. the three major metals present in brass alloys. The first contact of brass surfaces with the extraction solvent leads to an extensive Pb release which is comparable with that observed for Cu and Zn. Subsequent washings reduce markedly the Pb release, thus rising in evidence a progressive surface passivation. In particular, the Pb release found after four repeated washings turns out to approach the limit set by both Italian and USA governments for liquids used for food purposes when determined in neutral media, while it remains quite higher when evaluated in acid media. Release analyses conducted on nickel-covered brass pumps point out that the Niploy nickel coating process is very effective for brass surface protection, in that the Pb release is reduced of about three orders of magnitude, but a Ni release exceeding the relevant permitted level is in this case observed. 相似文献
105.
Methyl salicylate (MeS) is used as a chemical warfare agent simulant to test chemical protective garments and other individual personal protective gear. The accurate and real-time detection of this analyte is advantageous for various testing regimes. This paper reports the results of MeS vapor exposures on polymer-filled capacitance-based sensors at temperatures ranging from 15 °C to 50 °C under dry and humid conditions. Multiple capacitors were arranged in an array on a silicon chip each having a different sorptive polymer. The sensors used parallel-plate electrode geometry to measure the dielectric permittivity changes of each polymer when exposed to water and MeS vapor. Of the four polymers tested against MeS, the optimal polymer displayed near or sub-parts-per-million detection limits at 35 °C (0–80%RH). 相似文献
106.
107.
Naeem A. Virk Aziz-ur- Rehman Muhammad A. Abbasi Sabahat Z. Siddiqui Javed Iqbal Shahid Rasool Shafi U. Khan Thet T. Htar Hira Khalid Sabina J. Laulloo Syed A. Ali Shah 《Journal of heterocyclic chemistry》2020,57(3):1387-1402
The current study was aimed for the study of piperidine-based triazole compounds for their biological potential against various enzymes. A novel library of compounds, 9a-r , having piperidine, 1,2,4-triazole, and propanamides was synthesized through consecutive steps including the formation of sulfonamide, hydrazide, 1,2,4-triazole, and thio-ether. Initially, 4-methoxybenzenesulfonyl chloride ( 1 ) and ethyl isonipecotate ( 2 ) were utilized to develop ethyl 1-(4-methoxyphenylsulfonyl)-4-piperidinecarboxylate ( 3 ). The product 3 was converted into respective hydrazide ( 4 ) which was further cyclized into 1,2,4-triazole ( 5 ) nucleus. A series of propanamides, 8a-r , were synthesized from different amines, 6a-r . These electrophiles, 8a-r , were reacted with compound 5 under conventional and microwave-assisted protocols to acquire the library of hybrids, 9a-r . The structural confirmations were availed by 1H-NMR, 13C-NMR, and IR techniques. The whole series was evaluated for biological potential against acetylcholinesterase (AChE) and α-glucosidase enzymes. The biological evaluation ranges low to high in potential for different compounds based on the structural variations of synthesized compounds. Almost all the compounds remained active against both the enzymes except a few ones. The bovine serum albumin (BSA) binding study demonstrated the flow of drug in the body, and the docking study explained the interactions responsible for active behavior of synthesized compounds. 相似文献
108.
109.
The conformation of single molecules of dialkyl poly para phenylene ethynylenes (PPEs), electro-active polymers, is studied in solutions using molecular dynamics simulations. The conformation of conjugated polymers affects their electro-optical properties and therefore is critical to their current and potential uses, though only limited theoretical knowledge is available regarding the factors that control their configuration. The present study investigates the affects of molecular parameters including molecular weight of the polymer and chemical structure of the side chains of PPEs in different solvents on the conformation of the polymers. The PPEs are modeled atomistically where the solvents are modeled both implicitly and explicitly. The study finds that PPEs assume extended configuration which is affected by the length of the polymer backbone and the nature and length of substituting side chains. While the polymer remains extended, local dynamics is retained and no long range correlations are observed within the backbone. The results are compared with scattering experiments. 相似文献
110.
Mayer M Lang PT Gerber S Madrid PB Pinto IG Guy RK James TL 《Chemistry & biology》2006,13(9):993-1000
We have synthesized a series of phenothiazine derivatives, which were used to test the structure-activity relationship of binding to HIV-1 TAR RNA. Variations from our initial compound, 2-acetylphenothiazine, focused on two moieties: ring substitutions and n-alkyl substitutions. Binding characteristics were ascertained via NMR, principally by saturation transfer difference spectra of the ligand and imino proton resonance shifts of the RNA. Both ring and alkyl substitutions manifested NMR changes upon binding. In general, the active site, while somewhat flexible, has regions that can be capitalized for increased binding through van der Waals interactions and others that can be optimized for solubility in subsequent stages of development. However, binding can be nontrivially enhanced several-fold through optimization of van der Waals and hydrophilic sites of the scaffold. 相似文献