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251.
252.
LL Handley R Azcón Ruiz Lozano JM CM Scrimgeour 《Rapid communications in mass spectrometry : RCM》1999,13(13):1320-1324
It has long been evident that plant (15)N chiefly reflects the processes which fractionate (15)N/(14)N rather than the (15)N of plant N source(s). It has emerged recently that one of the most important fractionating processes contributing to the whole plant (15)N is the presence/absence, type or species of mycorrhiza, especially when interacting with nutrient deficiency. Ecto- and ericoid mycorrhizas are frequently associated with (15)N-depleted foliar (15)N, commonly as low as -12 per thousand. As shown by the present study, plants having no mycorrhiza, or those infected with various species of arbuscular mycorrhiza (AM)-forming fungi, interact with varying concentrations of soil nitrogen [N] and moisture to enrich plant (15)N by as much as 3.5 per thousand. Hence the lack of a mycorrhiza, or variation in the species of AM-forming fungal associations, can account for about 25% of the usually reported variations of foliar (15)N found in field situations and do so by (15)N enrichment rather than depletion. Copyright 1999 John Wiley & Sons, Ltd. 相似文献
253.
E. Abad J. Ortega Y. J. Dappe F. Flores 《Applied Physics A: Materials Science & Processing》2009,95(1):119-124
A local orbital DFT-approach combined with a “scissor”-operator is used to obtain the Charge Neutrality Level and the screening
parameter in the benzene/Au(111) and C60/Au(111) interfaces. The “pillow” dipole and interface Fermi level are also calculated. The total dipole induced across the
interface is compared with the experimental evidences: while the agreement for C60/Au(111) is excellent, for benzene/Au(111), some discrepancies appear that are discussed in the light of other models. 相似文献
254.
Somayeh Soleimani‐Amiri Zinatossadat Hossaini Maryam Arabkhazaeli Hossein Karami Saeid Afshari Sharif Abad 《中国化学会会志》2019,66(4):438-445
In this paper, we report the synthesis of pyrimido[2,1‐a] isoquinoline and pyrimido[1,2‐a]quinoline derivatives in high yields from the reaction of isoquinoline or quinoline, activated acetylenic compounds, and amides in the presence of ZnO nanorods (ZnO‐NRs) as catalyst under solvent‐free conditions at room temperature. ZnO‐NRs show good improvement in the yield of the product and significant reusability. Also, the antioxidant activities of the some of the newly synthesized compounds were carried out by 1,1‐diphenyl‐2‐picrylhydrazyl (PDDH) radical trapping and ferric ion reducing potential tests and compared with those of the synthetic antioxidants 2‐tert‐butylhydroquinone (TBHQ) and butylated hydroxytoluene (BHT). These compounds do not show good DPPH radical scavenging but display good ferric ion reducing power. 相似文献
255.
During a study on iodocyclocarbamation reactions of 2-styryl-4-piperidones, a novel ring contraction was observed. Iodocyclocarbamation of 2-styryl-4-piperidone 3 gave the bicyclic carbamate 4. Reduction of 4 under free-radical conditions effected a stereoselective ring contraction to provide oxazolidinone 6. A three-electron-three-center mechanism is proposed. 相似文献
256.
A two-dimensional Cellular Automata model is proposed to simulate the exit dynamics of occupant evacuation. Concerning the exit width and the door separation, we put forward some useful standpoints: (1) exit width should be bigger than a critical value, and the door separation should be neither too small nor too big; (2) for single-exit door, with the increase of exit width, the flux per unit width will decrease but the total flux will always increase; (3) the total flux of the exit is an increasing nonlinear function of the exit width; (4) the optimal value of the door separation does not vary with the value of exit width; (5) the layout of exits should be symmetry. Those results are helpful in performance-based design of building. 相似文献
257.
258.
259.
We describe a simple method to measure the top quark mass in the
channel that may be useful in Run II of D? detector. The method is validated by applying it to the Run Ib eμ data. 相似文献
260.
JM Chatterjee M Saha Sarkar S Bhattacharya P Banerjee S Sarkar RP Singh S Murulithar RK Bhowmik 《Pramana》2001,57(1):165-169
High-spin states of 95,97Mo (Z=42, N=53,55) nuclei have been investigated through 82Se(18O, xn) reaction at Eb=60 MeV. The level scheme in 95Mo has been observed upto ≏ 10 MeV in the present experiment. The level structure shows mainly single particle character.
In 97Mo, the ground state level sequence has been extended to ≏ 4.5 MeV while the previous information had been up to 2.4 MeV.
A negative parity band built on 1437 keV (11/2−) excited state has been extended to 5.5 MeV. The structure seems to show a coexistence of single particle and collective
modes of excitation. Properties of both the nuclei have been compared with shell model calculations using OXBASH. 相似文献