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961.
Cold acclimation of Lolium L. and Zoysia Willd. Grass cultivars significantly increased regrowth of cryopreserved meristems. One wk of cold acclimation improved recovery following cryopreservation but extended acclimation (4-8 wk) resulted in the best regrowth. Cold acclimation also significantly increased the dehydration tolerance of both Zoysia and Lolium meristems. Lolium apices cold acclimated for 4 wk produced 60-100% regrowth following cryopreservation by slow freezing or encapsulation-dehydration. Cold-acclimated Zoysia had greater than 60% regrowth following encapsulation-dehydration when beads were dehydrated to less than 22% water content. Non-acclimated meristems of both genera had little or no regrowth. Thawed meristems grew quickly without callus formation and the plantlets produced were transplanted to pots in the greenhouse after 4 to 6 wk. Samples of each cultivar were stored in liquid nitrogen as part of the U.S. National Plant Germplasm System. 相似文献
962.
Sola IR Chang BY Santamaria J Malinovsky VS Krause JL 《Physical review letters》2000,85(20):4241-4244
In this Letter we describe a method for population transfer using intense, ultrafast laser pulses. The selectivity is accomplished by careful shaping of light-induced potentials (LIPs). Creation and control of the LIPs is accomplished by choosing pairs of pulses with proper frequency detunings and time delays. As an example, selective population transfer is demonstrated for a three-state model of the sodium dimer. 相似文献
963.
We consider the Kaluza-Klein (KK) scenario in which only gravity exists in the bulk. Without the assumption of symmetric connection, the presence of brane fermions induces torsion. The result is a universal axial contact interaction that dominates those induced by KK gravitons. This enhancement arises from a large spin density on the brane. Using a global fit to Z-pole observables, we find the 3sigma bound on the scale of quantum gravity to be 28 TeV for n = 2. If Dirac or light sterile neutrinos are present, the data from SN1987A increase the bound to sqrt[n] M(S)>/=210 TeV. 相似文献
964.
965.
966.
J. Ren P. C. W. Fung C. Chang G. X. Shen G. Lu F. H. Y. Chan K. J. Liu J. Shen 《Applied magnetic resonance》2007,32(3):243-255
Electron paramagnetic resonance (EPR) spin trapping technology is a sensitive and unambiguous method for detection of nitric
oxide (NO). Due to the short lifetime, NO must be trapped before EPR measurement. There are two EPR spin trapping techniques
used currently, including the detections of EPR signals of diethyldithiocarbamate-iron-nitric oxide (DETC2-Fe2+-NO) and nitrosyl hemoglobin (HbNO). In this study, we firstly investigated the kinetics of the EPR signal of DETC2-Fe2+-NO in normal and ischemia-reperfused kidneys. In normal rat kidneys, the signal of DETC2-Fe2+-NO was found at 5 min after the spin trappers Fe2+/DETC were administrated, the peak concentration was at 15 min and the period with relatively stable signal intensity was
at the time range from 15 to 70 min. In the ischemia-reperfused rat kidneys, the signal of DETC2-Fe2+-NO was increased at 30 min of ischemia and decreased at 60 min of ischemia after the occlusion of renal artery (corresponding
to the time course of 60 and 90 min after Fe2+/DETC injection respectively). We then investigated the EPR signal of HbNO in blood. No characteristic HbNO signal was found
in the rats of the sham control and 30 min of ischemia. An HbNO signal occurred in the rats exposed to 60 min of ischemia
and it became pronounced with increased duration of reperfusion. The signal intensity reached a plateau at 150 min of reperfusion.
The results suggest that the DETC2-Fe2+-NO signal can be only suitable for the NO measurement in the short-term ischemia-reperfusion model, whereas the HbNO signal
can be applied to represent NO in the relatively long-term ischemia-reperfusion model. In addition, NG-nitro-L-arginine (L-NAME) and allopurinol were used to identify the source of NO. By detecting the HbNO signal, we demonstrated
that the activation of xanthine oxidase is an important source of NO formation at the long-term period of ischemia and reperfusion.
Authors' address: Jiangang Shen, School of Chinese Medicine, University of Hong Kong, 10 Sassoon Road, Hong Kong SAR, China 相似文献
967.
Gun Sang Jeon Chia-Chen Chang Jainendra K. Jain 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,55(3):271-282
We review and extend the composite fermion theory for semiconductor quantum dots in high magnetic fields. The mean-field model
of composite fermions is unsatisfactory for the qualitative physics at high angular momenta.
Extensive numerical calculations demonstrate that the microscopic CF theory,
which incorporates interactions between composite fermions, provides an excellent qualitative and quantitative account
of the quantum dot ground state down to the largest angular momenta studied,
and allows systematic improvements by inclusion of mixing between composite
fermion Landau levels (called Λ levels). 相似文献
968.
测量了氢气离子转动分辨的真空紫外脉冲场电离光电子谱.涵盖了15.30?18.09 eV能量范围内的H2+(X2§+g , v+=0?18,N+=0?5)?H2(X1§+g , v00=0, J00=0?4)的电离跃迁. 通过基于Buckingham-Orr-Sichel(BOS)模型的光谱拟合和对氢气离子振动带H2+(X2§+g ,v+=0?18)的转动光谱的分析, 发现实验上只观察到对应于¢N=N+-J00=0,§2的转动跃迁. 振动量子数v+ 越高,¢N=0的转动跃迁越占主导地位, 而转动谱线强度受邻 相似文献
969.
W.Y. Zhang C.H. Chiu L.C. Zhang K. Biswas H. Ehrenberg W.C. Chang J. Eckert 《Journal of magnetism and magnetic materials》2007
The effect of refractory element addition on phase transformation, crystallization behavior and magnetic properties of Pr8.5Fe81.5B10 (addition-free) and Pr8.5Fe81.5M2B10 (M=V, Cr, Nb, Zr, Ti) ribbons has been investigated. The annealed addition-free ribbon as well as the samples with V or Cr additions are mainly composed of the metastable Pr2Fe23B3 phase, whereas annealed ribbons with Nb, Zr or Ti additions primarily consist of Pr2Fe14B and a minor amount of Fe3B/boride. The complete suppression of the metastable Pr2Fe23B3 phase due to Nb, Zr or Ti additions leads to a significant enhancement of the magnetic properties. For example, the remanence, the coercivity and the energy product are remarkably increased from 2.5 kG, 0.4 kOe and 0.2 MG Oe for the addition-free material to 9.2 kG, 4.7 kOe and 7.6 MG Oe for the specimens with Nb addition. The successful elimination of the metastable Pr2Fe23B3 phase is believed to profit from two factors: (a) Nb, Zr or Ti atoms substitute the Pr site, comparatively increase the Pr content, and thus inhibit the nucleation of Pr-lean Pr2Fe23B3 phases, and (b) the formation of Nb, Zr, or Ti borides consumes some part of B, which hinders the generation of the B-rich Pr2Fe23B3 phase. 相似文献
970.
Composite coating of Ni-Co/Al2O3 was deposited in Ce2(SO4)3 containing electrolyte by pulse reverse current (PRC) method. The effect of Ce2(SO4)3 in electrolyte on morphology, microstructure, composition, micro-hardness and residual macrostress of composite coating was investigated. The results indicates that with addition of Ce2(SO4)3 in electrolyte, the composite coating becomes uniform, compact and possesses finer grains, the composite content of Al2O3 is enhanced, the micro-hardness of composite coating is improved, while the residual macrostress is decreased. 相似文献