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41.
Triglycerides are a major component of many important biological entities such as lipoproteins and lipid droplets. This work focuses on two common triglycerides, tripalmitin and triolein, which have been simulated through atomistic molecular dynamics at temperatures of 310 and 350 K for 300-700 ns. In these systems, both structural and dynamical properties have been characterized, paying particular attention to understanding the packing of triglyceride molecules and their molecular conformations. Additionally, we study the liquid-to-crystalline phase transition of tripalmitin through a temperature quench from the high-temperature isotropic liquid phase to 310 K, corresponding to a polymorphic, crystalline-like phase. The transition is characterized in detail through density, average molecular shape, and, in particular, the relevant order parameter describing the transition. 相似文献
42.
Sørensen LM Nielsen KF Jacobsen T Koch AG Nielsen PV Frisvad JC 《Journal of chromatography. A》2008,1205(1-2):103-108
A method for determination of mycophenolic acid (MPA) in dry-cured ham, fermented sausage and liver paté is described. MPA was extracted from meat with bicarbonate-acetonitrile, further cleaned-up by mixed mode reversed phase-anion exchange and detected using a LC-MS system with electrospray ionisation-time-of-flight detection. The limit of detection was 4 microg/kg in sausage and 6 microg/kg in ham and paté. The method was successfully used for quantification of MPA in dry-cured ham and liver paté artificially inoculated with Penicillium brevicompactum. Levels ranged from 190 microg/kg in centre to 11 mg/kg in surface of ham and from 150 microg/kg in bottom to 14 mg/kg in surface of paté. 相似文献
43.
Micro fluid segment technique for screening and development studies on Danio rerio embryos 总被引:1,自引:0,他引:1
The applicability of micro fluid segments for studying the behaviour of multicellular systems, in particular embryonic development, has been investigated. It was found that eggs from the zebrafish Danio rerio can be introduced into micro fluid segments without serious damage by using perfluoromethyldecalin (PP9) as the carrier liquid and Teflon (PTFE) as the tube material. The development processes of fish embryos were observed over a time period of 80 hours, until hatching time. After five days, the fish larvae were brought out of the micro fluid segments and transferred into breeding reservoirs. Effects of the membrane-damaging anionic surfactant sodium dodecyl sulfate (SDS) alone and SDS with the addition of CuCl(2) (copper(II) chloride) were investigated. By analyzing different end points, we found inhibiting and also supporting effects on the development of the embryos. Low SDS concentrations with and without copper(II) ions were supportive, while higher SDS concentrations led to negative impacts on the development of the embryos. The results showed that automated micro screening processes with complex biological systems can be performed using microfluidic systems and are applicable for future toxicological and drug screening studies. 相似文献
44.
Differentiation of organically and conventionally produced milk by stable isotope and fatty acid analysis 总被引:2,自引:0,他引:2
Increasing sales of organic milk mean intensified tests for authenticity are required. In addition to comprehensive documentation,
analytical methods to identify organic milk, and thus to differentiate it from conventional milk, are needed for consumer
protection. Because the composition of milk is fundamentally dependent on the feeding of the cows, thirty-five samples from
both production systems in Germany, including farm and retail milk, were collected within 12 months, to reflect seasonal variation,
and appropriate properties were analysed. Fatty acid analysis enabled organic and conventional milk to be completely distinguished,
because of the higher α-linolenic acid (C18:3ω3) and eicosapentaenoic acid (C20:5ω3) content of the former. Organic milk fat
contained at least 0.56% C18:3ω3 whereas the maximum in conventional milk was 0.53%. Because of the parallel seasonal course
of the C18:3ω3 content of organic and conventional retail samples, however, time-resolved comparison at the five sampling
dates resulted in a clearer difference of 0.34 ± 0.06% on average. Analysis of stable carbon isotopes (δ13C) also enabled complete distinction of both types of milk; this can be explained by the different amounts of maize in the
feed. For conventional milk fat δ13C values were −26.6‰ or higher whereas for organic milk fat values were always lower, with a maximum of −28.0‰. The time-resolved
average difference was 4.5 ± 1.0‰. A strong negative correlation (r = −0.92) was found between C18:3ω3 and δ13C. Analysis of a larger number of samples is required to check the preliminary variation ranges obtained in this pilot study
and, probably, to adjust the limits. Stable isotopes of nitrogen (δ15N) or sulfur (δ34S) did not enable assignment of the origin of the milk; in cases of ambiguity, however, some trends observed might be useful
in combination with other properties.
Figure Correlation (r = −0.92) between δ13C value and C18:3ω3 content of milk fat from different production systems 相似文献
45.
Hydroxyl radical intermediates are trapped in calcined Cu/HY zeolites in the presence of oxygen and water. This suggests that hydrogen peroxide is formed in situ from oxygen. Br?nsted acids enhance the formation of the radicals. 相似文献
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Synthesis and Crystal Structures of DyPt8P2 and Mg10?xPt9P7 Single crystals of DyPt8P2 (a = 9.260(2), b = 4.005(1), c = 9.633(2) Å, β = 102.64(3)°) were grown by heating the elements in a melt of NaCl/KCl at 1100 °C. The phosphide crystallizes in a new type of structure (I2/m; Z = 2) which consists of fragments in the shape of a cubic close packing built up by three fourths of the platinum atoms. The Dy atoms are coordinated by twelve Pt and four P atoms forming a distorted hexagonal prism which is fourfold capped by Pt atoms. Needles of Mg10?xPt9P7 (a = 18.121(4), b = 23.316(5), c = 3.848(1) Å) were obtained by reaction of the elements in molten lead at 1000 °C. The main feature of the new type of structure (Pbam; Z = 4) is an oval ring of pentagonal prisms formed by each six Pt and four P atoms. The prisms are linked with each other via common faces and they are centered by Mg atoms. Another Mg atoms are located in holes of the three‐dimensional [Pt9P7] network. It is remarkable, that one of the ten different crystallographic sites of the Mg atoms is occupied incompletely inducing the composition Mg10?xPt9P7 with x = 0.86. 相似文献
50.
Yahav-Levi A Goldberg I Vigalok A Vedernikov AN 《Journal of the American Chemical Society》2008,130(2):724-731
The platinum(IV) complex trans-(dmpe)Pt(IV)(Ar)2I2 (2, dmpe = 1,2-dimethylphosphinoethane, Ar = 4-FC6H4) rapidly reacts, upon moderate heating in solution under ambient light, via two distinct pathways: isomerization to the corresponding cis-isomer (3) and Ar-I reductive elimination to give (dmpe)Pt(II)(Ar)I (4). Complex 3 undergoes, upon prolonged heating at high temperatures, an exclusive Ar-Ar reductive elimination reaction to give (dmpe)Pt(II)I2. Experimental and DFT studies showed that the 2-to-3 isomerization proceeds via three pathways: photochemical or thermal phosphine chelate opening and a mechanism involving cleavage of the Pt-I bond. The isomerization reaction is significantly slowed down but not stopped in the absence of light or in the presence of an excess of tetra-n-butylammonium iodide. On the other hand, the Ar-I reductive elimination from 2 proceeds via the Pt(delta+)-I(delta-) ion pairlike transition state. Use of the rigid dmpe analogue 1,2-dimethylphosphinobenzene (dmpbz) as the ligand shuts down the chelate ring-opening isomerization pathway and enables faster Ar-I reductive elimination thus making the latter reaction the major reaction route for the dmpbz supported trans-diiodo Pt(IV) complex 8. 相似文献