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41.
《Electroanalysis》2006,18(10):971-975
The highly sensitive voltammetric detection of the 2,3‐dimethyl‐2,3‐dinitrobutane (DMNB), a required additive to commercial plastic explosives, is described. The protocol relies on a fast square‐wave voltammetric measurement of the DMNB explosive taggant at an unmodified carbon fiber electrode using a phosphate buffer (pH 7.0) solution. Different solutions and working electrodes were evaluated. Under the optimal conditions, a linear response is observed over the 300–3000 μg/L DMNB concentration range examined, with a detection limit of 60 μg/L. A highly stable response, with a relative standard deviation (RSD) of 2.6%, is observed for 30 repetitive measurements. Such electrochemical approach offers great promise for a simple, rapid, sensitive and inexpensive field screening of plastic explosives. Preliminary data illustrate the utility of electrochemical detection for electrophoretic microchips for the simultaneous measurements of DMNB, cyclotrimethylenetrinitramine (RDX) and pentaerythritoltetranitrate (PETN). 相似文献
42.
The effectiveness of applying a pulsed corona discharge to the destruction of olfactory pollution in air was investigated.
This paper presents a comparative study of the decomposition of three representative sulfide compounds in diluted concentrations:
hydrogen sulfide (H2S), dimethyl sulfide (DMS), and ethanethiol (C2H5SH), which could be completely removed when a sufficient but reasonable energy density was deposited in the gas. DMS showed
the lowest energy cost (around 30 eV/molecules); C2H5SH and H2S had an EC of respectively 45 eV and 115 eV. The efficiency of the non-thermal plasma process increased with decreasing the
initial concentration of sulfide compounds, while the energy yield remained almost unchanged. SO2 was the only identified byproduct of H2S decomposition, but the sulfur balance suggests the formation of undetected SO3. The byproducts analyzed during the degradation of DMS and C2H5SH enabled to propose a reaction mechanism, starting with radical attack and breaking of C–S bonds. 相似文献
43.
《Analytical letters》2012,45(12):2003-2011
It is difficult to determine sulfur-containing volatile organic compounds in the atmosphere because of their reactivity. Primary off-line techniques may suffer losses of analytes during the transportation from field to laboratory and sample preparation. In this study, a novel method was developed to directly measure dimethyl sulfide at parts-per-billion concentration levels in the atmosphere using vacuum ultraviolet single photon ionization time-of-flight mass spectrometry. This technique offers continuous sampling at a response rate of one measurement per second, or cumulative measurements over longer time periods. Laboratory prepared samples of different concentrations of dimethyl sulfide in pure nitrogen gas were analyzed at several sampling frequencies. Good precision was achieved using sampling periods of at least 60 seconds with a relative standard deviation of less than 25%. The detection limit for dimethyl sulfide was below the 3 ppb olfactory threshold. These results demonstrate that single photon ionization time-of-flight mass spectrometry is a valuable tool for rapid, real-time measurements of sulfur-containing organic compounds in the air. 相似文献
44.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(39):12068-12072
The development of a new decarboxylative cross‐coupling method that affords terminal and substituted alkynes from various carboxylic acids is described using both nickel‐ and iron‐based catalysts. The use of N‐hydroxytetrachlorophthalimide (TCNHPI) esters is crucial to the success of the transformation, and the reaction is amenable to in situ carboxylic acid activation. Additionally, an inexpensive, commercially available alkyne source is employed in this formal homologation process that serves as a surrogate for other well‐established alkyne syntheses. The reaction is operationally simple and broad in scope while providing succinct and scalable avenues to previously reported synthetic intermediates. 相似文献
45.
《Comptes Rendus Chimie》2016,19(5):556-565
A smectogen liquid crystal based on benzoate units has been synthesized and structurally characterized by FTIR and 1H NMR spectroscopy. Besides, its structure and supramolecular arrangement in the crystalline state was demonstrated by single crystal X-ray diffraction measurements. The thermotropic behaviour, monitored by differential scanning calorimetry and polarized light microscopy, consists in the formation of an enantiotropic smectic mesophase with a direct first order transition from the isotropic to smectic mesophase, and with its thermal stability range superposed on human body temperature. The smectogen liquid crystal has moderate wettability – suitable for biocompatible materials and presents good antipathogenic activity against gram positive and gram negative bacteria and fungus.All these properties recommend the understudied liquid crystal to be used in biochemical and biological applications. 相似文献
46.
47.
Jeffrey Trautmann Alirica I. Suarez Pakamas Tongcharoensirikul Gregory W. Muth Charles M. Thompson 《Phosphorus, sulfur, and silicon and the related elements》2013,188(2):471-477
Dimethyl thiophosphite reacts with aliphatic aldehydes and ketones, Michael acceptors, and N-benzyl imines to afford excellent yields of f -hydroxy phosphonothionates, g -substituted phosphonothionates and f -amino phosphonothionates, respectively. Dealkylation of f -amino phosphonothionates affords N-benzyl f -amino phosphonothioic acids. Dimethyl thiophosphite reacts with electrophiles at a significantly greater rate than dimethyl phosphite. 相似文献
48.
Purnanand P. D. Shakya Shefali Saxena M. Sharma Basant Lal 《Phosphorus, sulfur, and silicon and the related elements》2013,188(5):1093-1099
Based on 31 P NMR studies of thionyl chloride reaction with dialkyl alkylphosphonothionates, a method for preparation of alkylphosphonic dichloride has been investigated. A mechanism via intermediacy of ester chloride is suggested. 相似文献
49.
Issa Yavari Mansoureh Aghazadeh Mohsen Tafazzoli 《Phosphorus, sulfur, and silicon and the related elements》2013,188(5):1101-1107
Ethyl 2-arylamino-2-oxo-acetates undergo a complex reaction with dimethyl acetylenedicarboxylate in the presence of triphenylphosphine to produce dimethyl 1-aryl-4-ethoxy-5-oxo-4,5-dihydro-1 H -pyrrole-2,3-dicarboxylates in good yields. Dynamic NMR study of dimethyl 1-(2-methylphenyl)-4-ethoxy-5-oxo-4,5-dihydro-1 H -pyrrole-2,3-dicarboxylate shows a fairly high energy barrier ( j G p = 53.2 kJmol m 1 ) for rotation around the N-aryl single bond, which leads to an observable atropisomerism. 相似文献
50.
R. HekmatShoar S. Souri F. Faridbod 《Phosphorus, sulfur, and silicon and the related elements》2013,188(7):1457-1461
An efficient process that converts 2-hydroxybenzaldehyde and their derivetives to chromene derivatives via intramolecular Wittig reaction is described. 相似文献