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131.
Vesna Nikolić Dušica Ilić Ljubiša Nikolić Mihajlo Stanković Milorad Cakić Ljiljana Stanojević Agneš Kapor Mirjana Popsavin 《Central European Journal of Chemistry》2010,8(4):744-749
The inclusion complex β-cyclodextrin:nifedipin was prepared in solid state by coprecipitation with 1:1 mol ratio. The structure
of the obtained complex and nifedipin was characterized by use of X-ray diffraction (XR), infrared spectroscopy (FTIR), nuclear
magnetic resonance (NMR), and differential scanning calorimetry (DSC) methods. The photodegradation of nifedipin and the β-cyclodextrin:nifedipin
inclusion complex in solid state was monitored under natural daylight by infrared spectroscopy, whereby the free nifedipin
degraded four to five times faster than the complexed nifedipin. The photodegradation products of both free and complexed
nifedipin, formed during irradiation at 350 nm (with corresponding energy flux of 18 W m−2) were monitored by liquid chromatography during various time intervals. The speed of formation of nitroso- and nitro-phenyl
derivatives by nifedipin irradiation was significantly higher than those of complexed nifedipin irradiation, which indicates
its increased photostability in the inclusion complex. The effect on this property is significant because it contributes both
to the improvement of the therapeutic effect of nifedipin and to the safer application thereof.
相似文献
132.
Ivana Kovačević Mirjana Popsavin Marko V. Rodić Vesna Kojić Velimir Popsavin 《Tetrahedron letters》2019,60(9):684-687
A new asymmetric synthesis of the naturally occurring styryl lactone cardiobutanolide and two novel analogues have been achieved starting from d-xylose. The key steps of the synthesis included an initial zinc mediated reductive THF-ring opening, stereoselective olefination and Sharpless asymmetric dihydroxylation. It was shown that cardiobutanolide (1) exhibits promising in vitro antitumour properties against certain human neoplastic cell lines. It was more potent than the commercial anticancer agent doxorubicin against three cell lines (K562, HL-60 and Raji). 相似文献
133.
134.
Vancik H Simunic-Meznaric V Mestrovic E Halasz I 《The Journal of organic chemistry》2004,69(14):4829-4834
Thermal dimerization of nitroso compounds in the solid state was investigated by using para-substituted nitrosobenzenes as model compounds. A mechanism that includes the interplay of topochemical reaction trajectories and phase transfer was proposed on the basis of FT-IR spectroscopic kinetics, time-resolved powder diffraction, and low-temperature X-ray structure determination. From shapes of the kinetic curves analyzed on the basis of the Avrami model, it was found that phase transfer could be triggered by a dimerization reaction of para-substituted nitrosobenzene to azodioxide, which, in turn, can be caused by different packing factors such as disorder in the starting nitroso monomer crystals. Since the represented model can be extended to a broad series of compounds, we propose it as a general method for investigations of solid-state reaction mechanisms. 相似文献
135.
Jelena S. Nikolic Vesna P. Stankov Jovanovic Marija V. Dimitrijevic Dragan J. Cvetkovic Ljiljana P. Stanojevic Ljubisa B. Nikolic 《International journal of environmental analytical chemistry》2017,97(2):112-123
Dichloromethane soil samples extracts were prepared using Soxhlet extraction technique, and after clean-up step, gas chromatography-mass spectrometry analysis of 16 priority polycyclic aromatic hydrocarbons (PAHs) was carried out. A comparison of dispersive solid-phase extraction (dSPE) and column chromatography (cC), as clean-up techniques, was evaluated. Six different sorbents (silica, diatomaceous earth, primary–secondary amine, C18, clinoptilolite and florisil) were tested as dispersive clean-up sorbents versus activated silica and alumina for cC. Best results for three concentration levels among dSPE were obtained using diatomaceous earth, with recovery values in the range of 75–112% for 13 of 16 analysed compounds, while cC recoveries were in the range of 75–111% for all analysed PAHs. Analysis of 12 soil samples from urban area of Ni? (Serbia) singled out acenaphthene as the most abundant compound. 相似文献
136.
Adsorption of mycotoxins by organozeolites 总被引:3,自引:0,他引:3
Daković A Tomasević-Canović M Dondur V Rottinghaus GE Medaković V Zarić S 《Colloids and surfaces. B, Biointerfaces》2005,46(1):20-25
Adsorption of zearalenone (ZEN), ochratoxin A (OCHRA) and aflatoxin B1 (AFB1) on natural zeolite, clinoptilolite, modified with different amounts of octadecyldimethylbenzyl ammonium (ODMBA) ions was investigated. Results showed that adsorption of hydrophobic ionizable ZEN on unmodified zeolite tuff was very low and that adsorption on organozeolites increased with increasing hydrophobicity of the zeolitic surface. The adsorption was independent of the form of ZEN in solution and the solution pH, indicating that hydrophobic interactions with ODMBA are responsible for ZEN adsorption. Adsorption of low polar ionizable OCHRA on organozeolites also increased with increasing hydrophobicity of the zeolitic surface, however, OCHRA showed moderate adsorption on unmodified zeolitic tuff at pH 3. OCHRA adsorption on unmodified zeolite as well as on lower surface coverage of organozeolite was dependent on the form of OCHRA in solution; there was a decrease of adsorption at high pH, where OCHRA is in the anionic form. It indicated that at acidic pH, low surface coverage allows some combination of hydrophobic interaction with ODMBA and interactions with the surface of the zeolite. At higher surface coverage, the OCHRA adsorption was higher and practically independent of pH, indicating that the hydrophobic interactions of OCHRA with ODMBA are responsible for its adsorption. Nonionizable low polar AFB1 had a high affinity for the unmodified zeolitic tuff and the adsorption of AFB1 was greatly reduced for organozeolites, indicating that AFB1 does not have high tendency for hydrophobic interactions with ODMBA. pH dependence of AFB1 adsorption, while AFB1 has the same form at all pHs, demonstrated that the surface modification of the zeolite depends on pH and that these modifications have influence on its adsorption. The calculated dipole moments of neutral mycotoxin molecules: AFB1-9.5D, OCHRA-6.9D and ZEN-2.2D are in qualitative agreement with adsorption experimental data. 相似文献
137.
Boris Pejin Giuseppina Tommonaro Miodrag Glumac Dimitar Jakimov Vesna Kojic 《Natural product research》2018,32(5):616-620
This study aimed to screen in vitro antitumour activity of the redox couple avarol/avarone against the human malignant glioma cell line U-251 MG for the first time. Compared both with avarol and positive controls used (temozolomide and doxorubicin), avarone was found to be the most active compound with IC50 value below 1 μM (IC50 0.68 ± 0.04 μM, 96 h). Considerable less DNA damage in the cells treated with avarol and avarone vs. doxorubicin (105 & 123% vs. 299%, respectively; untreated U-251 MG cells were used as a control, 100%), coupled with no sign of cytotoxicity against the normal human foetal lung fibroblast MRC-5 cells (IC50 > 100 μM), has actually pointed out the importance of this marine sesquiterpenoid quinone structure as a promising lead compound in development of novel brain chemotherapeutics. 相似文献
138.
Jelena S. Nikolić Violeta D. Mitić Vesna P. Stankov Jovanović Marija V. Dimitrijević Marija D. Ilić Strahinja R. Simonović 《Analytical letters》2018,51(7):1087-1107
Polycyclic aromatic hydrocarbons (PAHs) represent priority contaminants, and the development of fast, reliable and accurate methods for their determination is of essential importance. The soil is a part of the environment which easily accumulates PAHs, making them available for transport to the air and water over long time periods and by plants through the food chain to humans. The aim of present study was to introduce a novel sorbent to the quick, easy, cheap, effective, rugged, and safe technique for soil sample preparation for the determination of 16 European Union priority PAHs by gas chromatography–mass spectrometry. Two solvent systems, 2:1 (v/v) hexane:acetone and ethyl acetate, were investigated in combination with five clean-up sorbents [Primary secondary amine (PSA), C18, florisil, clinoptilolite, and diatomaceous earth] in this study. The highest overall recovery of the method was achieved by the combination of hexane:acetone with clinoptilolite (recoveries of 70–110%) with limits of detection in the range of 0.60–1.53?µg?kg?1. The analysis of 20 soil samples from Ni?, Serbia resulted in the identification of 11 samples with concentration greater than the values prescribed by law. The ratios of phenanthrene/anthracene and fluoranthene/pyrene were used to elucidate the origin of the PAHs as pyrolytic. 相似文献
139.
The dynamic mechanical behaviour of high impact polystyrene (PS-HI), styrene/butadiene/styrene block copolymer (SBS) and PS-HI + SBS blends were investigated. Dynamic mechanical analysis (DMA) was performed in the temperature range −100°C to 100°C. The primary viscoelastic functions were determined. The copolymers PS-HI and SBS as well as PS-HI+SBS blends were investigated in creep-fatigue regime and relaxation at temperatures 25, 30, 35, 40 and 45°C. Dynamic mechanical behavior of PS-HI, SBS and PS-HI + SBS blends depends on the copolymer and blends composition, the hard phase content, time and temperature. With the decrement of the hard phase PS concentration, the loss tangent of the soft phase increases while the loss tangent of the hard phase and the storage modulus decrease. All samples have a single Tg of the hard phase and a single Tg of the soft phase. The glass transition temperatures decrease as the content of the PS phase decreases. At the constant load the creep values increase and those of creep modulus decrease over a period of time, for all examined samples. These effects are more pronounced in samples with lower content of hard phase and at higher temperatures. The time-temperature correspondence principle was applied to create master curves for the reference temperature 25°C for the creep modulus of PS-HI, SBS and PS-HI + SBS blends on a time scale far outside of the range measured by DMA experiments. These results enable us to predict the useful life of our copolymers and their blends in a wide range of time and temperature. 相似文献
140.
Zora Popovi Gordana Pavlovi
eljka Soldin Livio Racan Vesna Trali‐Kulenovi 《Acta Crystallographica. Section C, Structural Chemistry》2003,59(1):m4-m6
The title complex, [ZnCl2(C7H6N2S)2], contains a Zn centre with a distorted tetrahedral coordination sphere, involving two Cl− ligands and two endocyclic N atoms from the thiazole moiety [Zn—Cl = 2.2284 (7) and 2.2236 (7) Å, and Zn—N = 2.081 (2) and 2.041 (2) Å]. The interplanar angle between the two ligands is 79.32 (6)°. The amino groups participate in intermolecular N—H⋯Cl hydrogen bonds, with N⋯Cl distances in the range 3.463 (2)–3.519 (2) Å. 相似文献