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141.
De Souza D de Toledo RA Galli A Salazar-Banda GR Silva MR Garbellini GS Mazo LH Avaca LA Machado SA 《Analytical and bioanalytical chemistry》2007,387(6):2245-2253
The use of a copper solid amalgam electrode (CuSAE) for the analytical determination of triazine herbicides (atrazine and
ametryne) instead of the conventional hanging mercury drop electrode (HMDE) is reported. The results obtained using electroanalytical
methods utilizing each of these electrodes were also compared with those provided by the HPLC technique. The results indicated
that the CuSAE electrode can be used to detect the herbicides studied, since the detection limits reached using the electrode
(3.06 μg L−1 and 3.78 μg L−1 for atrazine and ametryne, respectively) are lower than the maximum values permitted by CONAMA (Brazilian National Council
for the Environment) for wastewaters (50 μg L−1) and by the US EPA (Environmental Protection Agency of the United States) in natural water samples (10.00 μg L−1). An electroanalytical methodology employing CuSAE and square wave voltammetry (SWV) was successfully applied to the determination
of atrazine and ametryne in natural water samples, yielding good recoveries (70.30%–79.40%). This indicates that the CuSAE
provides a convenient substitute for the HMDE, particularly since the CuSAE minimizes the toxic waste residues produced by
the use of mercury in HDME-based analyses. 相似文献
142.
Bateman KP Castro-Perez J Wrona M Shockcor JP Yu K Oballa R Nicoll-Griffith DA 《Rapid communications in mass spectrometry : RCM》2007,21(9):1485-1496
Metabolite identification studies involve the detection and structural characterization of the biotransformation products of drug candidates. These experiments are necessary throughout the drug discovery and development process. The use of high-resolution chromatography and high-resolution mass spectrometry together with data processing using mass defect filtering is described for in vitro and in vivo metabolite identification studies. Data collection was done using UPLC coupled with an orthogonal hybrid quadrupole time-of-flight mass spectrometer. This experimental approach enabled the use of MS(E) data collection (where E represents collision energy) which has previously been shown to be a powerful approach for metabolite identification studies. Post-acquisition processing with a prototype mass defect filtering program was used to eliminate endogenous interferences in the study samples, greatly enhancing the discovery of metabolites. The ease of this approach is illustrated by results showing the detection and structural characterization of metabolites in plasma from a preclinical rat pharmacokinetic study. 相似文献
143.
144.
Renata Toplak Jurij Svete Branko Stanovnik Simona Goli Grdadolnik 《Journal of heterocyclic chemistry》1999,36(1):225-235
Methyl 2-(benzyloxycarbonyl)aimno-3-dimemylaminopropenoate ( 2 ) was prepared from methyl N-(benzyloxycarbonyl)glycinate ( 1 ) and t-butoxybis(dimethylamino)methane, and used as a reagent for preparation of substituted 3-(benzyloxycarbonyl)amino-4H-quinolizin-4-ones 5 and 6 , ?2H-pyran-2-ones 17–19 , ?2H-1-benzopyran-2-ones 28–31 , and -naphthopyrans 32–35 , ?2H-pyrano[3,2-c]pyridine-2,5-dione 46 , -pyrano-[4,3-b]pyran-2,5-dione 47 , -pyrano[3,2-c]benzopyran-2,5-dione 48 , -pyrano[2,3-c]pyrazol-6-ones 49 and 50 , -pyrano[2,3-d]pyrirnidin-7-ones 51 and 52 derivatives. In the reaction of 2 with 1,3-diketones trisubsti tuted pyrroles 14–16 were formed. Selective removal of benzyloxycarbonyl group was achieved by cat alytic transfer hydrogenation with Pd/C in the presence of cyclohexene to afford free 3-amino compounds 7 , 8 , 20 , 36–38 and 53–57 in yields better than 80%. 相似文献
145.
Carosena Meola Giovanni Maria Carlomagno Antonino Squillace Umberto Prisco Renata Erica Morace 《Macromolecular Symposia》2005,228(1):273-286
The aim of this study was a non-destructive evaluation of composites through their behaviour under thermal stimulation. Such behaviour was monitored by infrared thermography. Several specimens were fabricated involving: glass/epoxy with inclusion of foreign materials; carbon/epoxy with backdrilled holes; carbon/epoxy with impact damage; Glare® failed in bearing way. The obtained results prove that infrared thermography is capable of detecting the materials inhomogeneities and/or damage listed above. In particular, lock-in thermography is capable of supplying useful information about: the distribution of the adhesive thickness in composite structures; the distribution of the paint thickness; the behaviour under load of aluminium layers and glass fibres in Glare®. 相似文献
146.
147.
A model of air coolers with a family of movable Tamman's test tubes, installed in a laboratory chamber furnace, crucible furnace and tube furnace, which allows regulation and simultaneous crystallization of several substances at different temperature gradients and crystallization rate intervals, for obtaining crystals are presented. 相似文献
148.
Micha W. Wieczorek Wiesaw R. Majzner Renata Kaczmarek Janina Baraniak Wojciech J. Stec 《Heteroatom Chemistry》1998,9(2):271-279
Two isomeric pairs of compounds, cis- and trans-2-morpholino-2-thiono-4-methyl-1,3,2-dioxaphosphinane ( 1A + 1B ) and 2-morpholino-2-oxo-4-methyl-1,3,2-dioxaphosphinane ( 2A + 2B ) were obtained and separated into the pure compounds by silica gel chromatography. Attempts at crystallization afforded 1A , 1B , and 2B . Each crystalline isomer was studied by the X-ray technique, and each crystal and molecular structures assigned. These studies revealed that 1B and 2B have exocyclic 4-CH3 and sulfur (for 1B ) or 4-CH3 and oxygen (for 2B ) in the diequatorial position (cis-geometry), while compound 1A possesses the 4-CH3 group in equatorial position while sulfur is in an axial position (trans-geometry). For all the examined compounds, all the basic geometrical parameters, such as bond lengths, bond and torsion angles, and the deformation of a chair conformation of the six-membered heterocyclic rings, have been established. Such unambiguous assignment of cis-trans geometry in both pairs of 1 and 2 allowed us to confirm the stereoretentive PS → PO conversion by means of OXONE® and the stereoinvertive mechanism of formic-acid catalyzed hydrolysis of phosphorothiomorpholidates. © 1998 John Wiley & Sons, Inc. Heteroatom Chem 9:271–279, 1998 相似文献
149.
Luca Banfi Andrea Basso Chiara Lambruschini Lisa Moni Renata Riva 《Chemical science》2021,12(47):15445
This perspective aims at celebrating the 100th anniversary of the discovery of the Passerini three component reaction. After being nearly neglected for many years, now this reaction has become quite popular, thanks to the achievements of the last 30 years, which have revealed several chances of exploitation in organic synthesis. Though not being comprehensive, this review means to show the various ways that have been used in order to expand the utility of the Passerini reaction. Post-MCR transformations to give heterocycles or peptidomimetics, variants through single component replacement, stereochemical issues, and applications in total syntheses will be especially covered.This perspective aims at celebrating the 100th anniversary of the discovery of the Passerini three component reaction. 相似文献
150.
Stanislav Šabata Jiří Hetflejš Renata Rychtáriková Gabriela Kuncová Kamil Lang Pavel Kubát 《Chemical Papers》2009,63(4):438-444
Three tetracationic porphyrins differing in the position of charged nitrogen atoms on the peripheral substituents — 5,10,15,20-tetrakis(N-methylpyridinium-4-yl)porphyrin (TMPyP4), 5,10,15,20-tetrakis(N-methylpyridinium-2-yl)porphyrin (TMPyP2), 5,10,15,20-tetrakis(4-trimethylammoniophenyl) porphyrin (TMAPP), and hydrophobic 5,10,15,20-tetraphenylporphyrin (TPP), were immobilized by adsorption
and encapsulation in poly(hydroxymethylsiloxane) (PHOMS). The so prepared porphyrin-PHOMS composites were characterized by
porosimetry, scanning electron microscopy, fluorescence and diffuse reflectance UV-VIS spectroscopy. It was found that porphyrins
are immobilized in the PHOMS matrix in the free base monomer form Their irradiation produced singlet oxygen O2(1Δg) with the lifetime of 10–30 μs. 相似文献