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101.
Pepaj M Wilson SR Novotna K Lundanes E Greibrokk T 《Journal of chromatography. A》2006,1120(1-2):132-141
In the present work, an orthogonal two-dimensional (2D) capillary liquid chromatography (LC) method for fractionation and separation of proteins using wide range pH gradient ion exchange chromatography (IEC) in the first dimension and reversed phase (RP) in the second dimension, is demonstrated. In the first dimension a strong anion exchange (SAX) column subjected to a wide range (10.5-3.5) descending pH gradient was employed, while in the second dimension, a large pore (4,000 A) polystyrene-divinylbenzene (PS-DVB) RP analytical column was used for separation of the protein pH-fractions from the first dimension. The separation power of the off-line 2D method was demonstrated by fractionation and separation of human plasma proteins. Seventeen pH-fractions were manually collected and immediately separated in the second dimension using a column switching capillary RP-LC system. Totally, more than 200 protein peaks were observed in the RP chromatograms of the pH-fractions. On-line 2D analysis was performed for fractionation and separation of ten standard proteins. Two pH-fractions (basic and acidic) from the first dimension were trapped on PS-DVB RP trap columns prior to back-flushed elution onto the analytical RP column for fast separation of the proteins with UV/MS detection. 相似文献
102.
Cato Brede Elsa Lundanes Tyge Greibrokk Stig Pedersen-Bjergaard 《Journal of separation science》1998,21(12):633-639
Simultaneous element-selective detection of the halogens and carbon was accomplished with capillary gas chromatography coupled with microplasma mass spectrometry. The microplasma ion source was a radio frequency plasma contained inside the last 4–5 cm of the 0.32 mm i.d. fused silica capillary column. The ion source was located inside the high vacuum housing of the MS, and only the GC carrier gas (2.3 mL min−1 of helium) was used for plasma generation. Atomic ions were detected in the positive mode. Detection limits were in the low picogram area, and the selectivity to carbon ranged from 8×102 for fluorine to higher than 104 for the other halogens. By introduction of both hydrogen and oxygen as reagent gases, peak tailing was avoided by suppression of analyte reactions with the silica walls of the ion source. Special attention was given to the fluorine-selective detection due to an interfering background species at m/z 19, assumed to be H3O+ originating from the reagent gases. The background signal was minimized by careful control of the power level. 相似文献
103.
Innocenti G Puricelli L Piacente S Caniato R Filippini R Cappelletti EM 《Chemical & pharmaceutical bulletin》2002,50(6):844-846
A new arylnaphthalene lignan glycoside, patavine (1), together with five known lignans, justicidin B (2), diphyllin (3), tuberculatin (4), majidine (5), and arabelline (6) were isolated from shoot cultures of Haplophyllum patavinum. The structure of the new compound was elucidated by extensive one-dimensional (1D) and two-dimensional (2D) NMR experiments and mass spectrometry. The cytotoxicity of compounds 1, and 3-6 against LoVo human colon carcinoma cells was investigated. 相似文献
104.
105.
Paolo Costa Iris Trosien Miguel Fernandez‐Oliva Elsa Sanchez‐Garcia Wolfram Sander 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2015,127(9):2694-2698
The fluorenyl cation is a textbook example for a 4π antiaromatic cation. However, contrasting results have been published on how the annelated benzene rings compensate the destabilizing effect of the 4π antiaromatic five‐membered ring in its core. Whereas previous attempts to synthesize this cation in superacidic media resulted in undefined polymeric material only, we herein report that it can be generated and isolated in amorphous water ice at temperatures below 30 K by photolysis of diazofluorene. Under these conditions, the fluorenylidene is protonated by water to give the fluorenyl cation, which could be characterized spectroscopically. Its absorption in the visible‐light range matches that previously obtained by ultrafast absorption spectroscopy, and furthermore, its IR spectrum could be recorded. The IR bands in amorphous ice very nicely match predictions from DFT and DFT/MM calculations, suggesting the absence of strong interactions between the cation and surrounding water molecules. 相似文献
106.
107.
Zenobi MC Luengo CV Avena MJ Rueda EH 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2008,70(2):270-276
An ATR-FIR study of the vibrational spectra of 1-hydroxyethane-1,1'-diphosphonic acid (HEDP), nitrilotris(methylenephosphonic acid) (NTMP) and N,N-bis(2-hydroxyethyl)aminomethylphosphonic acid (BHAMP) in aqueous solution is presented. The study was performed in the range of pH from 5 to 9, and bands assignments are given in the 2000-890 cm(-1) range. However, as phosphonates display bands due to the PO stretching vibration mainly in the 900-1200 cm(-1) range, the study is focused in this midinfrared region, which shows important changes as the pH changes, specially the nu(POH) at approximately 925 cm(-1) and nu(PO(3)(2-)) at approximately 970 cm(-1) vibrations. IR analyses give also evidences for the zwitterionic nature of BHAMP and NTMP in solution with a strong indication that the zwitterion in both compounds remains intact throughout the pH range investigated. The successive protonation steps with the decrease of pH were evidenced in the IR spectra of the three studied phosphonates. 相似文献
108.
Van Elslande E Guérineau V Thirioux V Richard G Richardin P Laprévote O Hussler G Walter P 《Analytical and bioanalytical chemistry》2008,390(7):1873-1879
Microsamples of pink cosmetic powders from the Greco–Roman period were analyzed using two complementary analytical approaches
for identification of the colouring agents (lake pigments originally manufactured from madder plants with an inert binder,
usually a metallic salt) present in the samples. The first technique was a methanolic acidic extraction of the archaeological
samples with an additional ethyl acetate extraction of the anthraquinone-type colouring agents which were identified using
high performance liquid chromatography coupled to electrospray ionization with high resolution mass spectrometry (LC–ESI–HRMS),
and the second was direct analysis of a microsample by laser desorption ionization–mass spectrometry (LDI–MS). The latter
technique is well suited when the quantity of samples is very low. This soft ionization technique enables the detection of
very small quantities of compounds using the combination of positive and negative-ion modes. It was also successfully applied
for the direct analysis of some laboratory-made reference compounds. However, the presence of lead in one of these ancient
samples induced a spectral suppression phenomenon. In this case and conditional on a sufficient quantity of available sample,
the former method is better adapted for the characterization of these anthraquinone-type molecules. This study also confirmed
that purpurin, munjistin, and pseudopurpurin are the principal colouring agents present in these ancient cosmetic powders
constituted from madder plants.
Presented at the Annual French National Symposium on Mass Spectrometry, Electrophoresis and Proteomics, 20–23 September 2007
in Pau, France. 相似文献
109.
Hyperbranched polyamidoamine as stabilizer for catalytically active nanoparticles in water 总被引:1,自引:0,他引:1
Marty JD Martinez-Aripe E Mingotaud AF Mingotaud C 《Journal of colloid and interface science》2008,326(1):51-54
Poly(amidoamine) hyperbranched polymers (HYPAM) were successfully used to synthesize platinum nanoparticles of ca. 1.8 nm and to stabilize these particles in water. Furthermore these hyperbranched-stabilized platinum nanoparticles proved to be effective and robust for hydrogenation reaction in water. 相似文献
110.
Cathrine Brecke Gundersen Liang Zhu Sofia Lindahl Shiyu Wang Steven Ray Wilson Elsa Lundanes 《Chromatographia》2017,80(9):1475-1481
Monoethanol (MEA)- and dimethyl (DMA)-nitramines are by-products of amine-based post-combustion CO2 capture (PCCC) processing, and are potentially carcinogenic. The compounds are challenging to measure, also with LC–tandem mass spectrometry (MS/MS), attributed to their high polarity and extreme proneness to matrix effects. In contrast to related methods, the MEA- and DMA-nitramines were simultaneously determined in aqueous soil extracts in less than 10 min using a 1 mm × 150 mm Atlantis® T3 (3 µm) C18 column. A mobile phase of water/methanol (90/10, v/v) and 2 mM acetic acid allowed for electrospray ionization (ESI) of both analytes [in contrast to the need for both ESI and atmospheric pressure chemical ionization (APCI) in related methods]. Polarity switching electrospray was required for the simultaneous detection of the analytes, and concentration limits of detection (LODs) in the aqueous soil extracts were ≤5.0 µg L?1 using an injection volume of 20 μL and no prior enrichment step. Matrix effects were compensated for using isotope-labelled internal standards, and satisfactory precision and linearity were obtained (within- and between-day precisions ≤19%, r 2 ≥ 0.995 for concentrations up to 500.0 µg L?1). To avoid signal decrease over time when measuring DMA-nitramine alone, the use of polarity switching was beneficial, in addition to frequent cleaning of the ion transfer capillary. The validated method can be used to determine nitramines in aqueous soil extracts, which is of importance as soil sorption is a determinant of the compounds’ environmental fate. 相似文献