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71.
We report the synthesis of biomass‐derived functionalized aromatic chemicals from furfural, a building block nowadays available in large scale from low‐cost biomass. The scientific strategy relies on a Diels–Alder/aromatization sequence. By controlling the rate of each step, it was possible to produce exclusively the meta aromatic isomer. In particular, through this route, we describe the synthesis of renewably sourced meta‐xylylenediamine (MXD). Transposition of this work to other furfural‐derived chemicals is also discussed and reveals that functionalized biomass‐derived aromatics (benzaldehyde, benzylamine, etc.) can be potentially produced, according to this route.  相似文献   
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73.
A method was developed for the simultaneous determination of selenomethionine (SeMet) and selenocysteine (SeCys) in meat (chicken and lamb muscles) and different offal tissues (heart, liver, kidney). The analytical procedure was based on the protein extraction with urea under reducing conditions (dithiothreitol), derivatization of SeCys and SeMet by carbamidomethylation with iodoacetamide (IAM) followed by quantitative proteolysis. The mixture of the derivatized Se-amino acids was purified by size-exclusion liquid chromatography (LC) and analysed by ion-paring reversed-phase HPLC–inductively coupled plasma mass spectroscopy (ICP MS). The quantification of SeCys and SeMet was carried out by the method of standard additions. 77SeMet was used to control the SeMet derivatization efficiency and recovery. The method was validated by the determination of the Se mass balance. The Se-amino acids accounted for 91 ± 8% of the total selenium (mean of 95 samples of seven tissues analysed over a period of 18 months). The method was applied to the discrimination of the contribution of selenoproteins (containing SeCys) and other Se-containing proteins (containing SeMet) in tissues of animals during supplementation studies (dose–effect and tolerance).  相似文献   
74.
Dirubidium divanadyl phyllooctasilicate, Rb2(VO)2[Si8O19], is the first known anhydrous diphyllosilicate containing VIV. The structure consists of silicate double layers which are separated by [V2O8]8− dimers and is related to that of the compounds A2Cu2[Si8O19] (A = Rb or Cs), although the title compound crystallizes in a noncentrosymmetric orthorhombic space group. The silicate double layers contain four tetrahedrally coordinated Si sites in general positions and 12 O sites, nine in general positions and the other three on mirror planes. The vanadyl dimers have two square‐pyramidally coordinated V sites (site symmetry m). There are two different 10‐ and 12‐fold coordinated Rb sites with site symmetry m, one of which is a split position located between the dimers in the interlayer space, while the other is in a channel within the silicate layer.  相似文献   
75.
The molecular mechanisms underlying odorant detection have been investigated using the chip based SPR technique by focusing on the dynamic interactions between transmembrane Olfactory Receptor OR1740, odorant ligands and soluble Odorant-Binding Protein (OBP-1F). The OR1740 present in the lipid bilayer of nanosomes derived from transformed yeasts specifically bound OBP-1F. The receptor preferential odorant ligand helional released bound OBP-1F from the OR-OBP complex, while unrelated odorants failed to do so. OBP-1F modified the functional OR1740 dose-response to helional, from a bell-shaped to a saturation curve, thus preserving OR activity at high ligand concentration. This unravels an active role for OBPs in olfaction, in addition to passive transport or a scavenger role. This sensorchip technology was applied to assessing native OBP-1F in a biological sample: rat olfactory mucus also displayed significant binding to OR1740 nanosomes, and the addition of helional yielded the dissociation of mucus OBP from the receptor.  相似文献   
76.
A novel approach for chitosan oligosaccharide (COS) separation by immobilized metal affinity chromatography (IMAC) based on the differences in the interactions of chelated copper (II) ions with various COS (dimers, trimers, tetramers) is described. Polyhydroxylic chromatographic supports (agarose CL-6B and silica) were functionalized with various chelating functions such as iminodiacetate (IDA), carboxymethyl-aspartate (CM-Asp) and tris(carboxymethyl)ethylenediamine (TED). The COS retention capacities of the columns were between 2 and 6 mg/cm(3), depending on the chelating group. The COS were separated and/or enriched up to 95% for dimer and trimer and 90% for the tetramer, with yields of 60-95%.  相似文献   
77.
The preparation of symmetric 2,2′‐dimethoxy‐10,10′‐biacridinyl‐9,9′‐dione atropisomers were obtained by the oxidative coupling of 9(10H)‐acridinone with 1,3‐dibromo‐5,5‐dimethyl‐imidazolidine‐2,4‐dione  相似文献   
78.
79.
The traceable and accurate measurement of biogas impurities is essential in order to robustly assess compliance with the specifications for biomethane being developed by CEN/TC408. An essential part of any procedure aiming to determinate the content of impurities is the sampling and the transfer of the sample to the laboratory. Key issues are the suitability of the sample container and minimising the losses of impurities during the sampling and analysis process. In this paper, we review the state-of-the-art in biogas sampling with the focus on trace impurities. Most of the vessel suitability studies reviewed focused on raw biogas. Many parameters need to be studied when assessing the suitability of vessels for sampling and storage, among them, permeation through the walls, leaks through the valves or physical leaks, sorption losses and adsorption effects to the vessel walls, chemical reactions and the expected initial concentration level. The majority of these studies looked at siloxanes, for which sampling bags, canisters, impingers and sorbents have been reported to be fit-for-purpose in most cases, albeit with some limitations. We conclude that the optimum method requires a combination of different vessels to cover the wide range of impurities commonly found in biogas, which have a wide range of boiling points, polarities, water solubilities, and reactivities. The effects from all the parts of the sampling line must be considered and precautions must be undertaken to minimize these effects. More practical suitability tests, preferably using traceable reference gas mixtures, are needed to understand the influence of the containers and the sampling line on sample properties and to reduce the uncertainty of the measurement.  相似文献   
80.
The densities and heat capacities of solutions of phosphoric acid, 0.05 to 1 mol kg-1, were measured using flow vibrating tube densitometry and differential Picker-type calorimetry at temperatures up to 623 K and at pressures up to 28 MPa. The standard molar volumes and heat capacities of molecular H3PO4(aq) were obtained, via the apparent molar properties corrected for partial dissociation, by extrapolation to infinite dilution. The data on standard derivative properties were correlated simultaneously with the dissociation constants of phosphoric acid from the literature using the theoretically founded SOCW model. This made it possible to describe the standard thermodynamic properties, particularly the standard chemical potential, of both molecular and ionized phosphoric acid at temperatures up to at least 623 K and at pressures up to 200 MPa. This representation allows one to easily calculate the first-degree dissociation constant of H3PO4(aq). The performance of the SOCW model was compared with the other approaches for calculating the high-temperature dissociation constant of the phosphoric acid. Using the standard derivative properties, sensitively reflecting the interactions between the solute and the solvent, the high-temperature behavior of H3PO4(aq) is compared with that of other weak acids.  相似文献   
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