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排序方式: 共有8197条查询结果,搜索用时 15 毫秒
11.
H. Hofsäss H. Feldermann R. Merk M. Sebastian C. Ronning 《Applied Physics A: Materials Science & Processing》1998,66(2):153-181
T /nS of nT rearrangements and nS atoms in the spike volume as the crucial parameter characterizing the ability of a given ion–target combination to achieve
complete rearrangement of the spike volume. nT/nS>1 is the optimum condition for diamondlike film growth. For aC films the ion energy dependence of nT/nS agrees well with the measured sp3 bond fraction. For Ar+-ion-assisted deposition of aC we find nT/nS>1 above 50 eV with no pronounced ion energy dependence. Furthermore, our model predicts optimum conditions for the formation
of cubic boron nitride between 50 eV and 3 keV.
Accepted: 14 October 1997 相似文献
12.
D. V. Aleksanyan V. A. Kozlov I. L. Odinets P. V. Petrovskii T. A. Mastryukova 《Russian Chemical Bulletin》2007,56(5):1049-1052
Diethoxyphosphorylthioacetamide in the reaction with 2,3-dichloroquinoxaline acted as a thionating reagent, giving diethoxyphosphorylacetonitrile
and 2-chloro-3-[(3-chloro-2-quinoxalinyl)thio]quinoxaline. Reactions of phosphorylthioacetamides with N-methylquinoxalinium iodide in alcohol media in the presence of a base proceeded stereoselectively to afford cis-3-phosphoryl-1,3,3a,4,9,9a-hexahydro-2H-pyrrolo[2,3-b]quinoxaline-2-thiones.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1010–1013, May, 2007. 相似文献
13.
L. A. Sviridova G. A. Golubeva S. V. Shorunov 《Chemistry of Heterocyclic Compounds》2006,42(9):1185-1189
3-Nitromethylpyrazolidine reacts with derivatives of unsaturated acids and reducing agents with the formation of polyfunctional
compounds of the pyrazolidine nucleus.
__________
Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1365–1369, September, 2006. 相似文献
14.
Analysis of cyanobacterial toxins (anatoxin-a, cylindrospermopsin, microcystin-LR) by capillary electrophoresis 总被引:4,自引:0,他引:4
Capillary zone electrophoresis (CZE) and micellar electrokinetic chromatography (MEKC) were applied to the simultaneous separation of cyanobacterial toxins (anatoxin-a, microcystin-LR, cylindrospermopsin). The analytical performance data of both methods, optimized for the three toxins, were similar with a precision of migration times smaller than 0.8 RSD% and a detection limit in the range of 1-4 microg/mL, using spectrophotometric detection at 230 nm. Both methods were applied to an analysis of cyanotoxins in water bloom samples and crude cyanobacterial extracts. The results obtained indicate that, for complex matrices, the sequential application of CZE and MEKC is necessary. It is recommended to use both CE techniques for the analysis of the same sample in order to confirm the results by an orthogonal approach. 相似文献
15.
Branko Stanovnik Uroš Urleb Miha Tišler 《Monatshefte für Chemie / Chemical Monthly》1987,118(5):601-606
An unequivocal synthesis of 5-chloro-7-methyl- (8) and 7-methyl-1,2,4-triazolo[1,5-a]pyrimidine (10) from 2-amino-4-chloro-6-methylpyrimidine (5) through the corresponding amidine6 and formamide oxime7 was developed. It was unambigously shown by comparison of the chemical shifts and the magnitude of coupling constants that the compounds obtained by condensation of 3-amino-1,2,4-triazole (12) and ethyl acetoacetate (13) and some further transformations are isomeric 5-methyl substituted 1,2,4-triazolo[1,5-a]pyrimidines1,9, and11.
Eine eindeutige Synthese einiger substituierter 1,2,4-Triazolo[1,5-a]pyrimidine
Zusammenfassung Es wurde ein eindeutiger Syntheseweg für 5-Chlor-7-methyl- (8) und 7-Methyl-1,2,4-triazolo[1,5-a]pyrimidin (10) ausgehend von 2-Amino-4-chlor-6-methylpyrimidin (5) über das entsprechende Amidin6 und das Formamidoxim7 entwickelt. Durch Vergleich von chemischen Verschiebungen und Kopplungskonstanten konnte eindeutig gezeigt werden, daß die Verbindungen, die bei der Kondensation von 3-Amino-1,2,4-triazol (12) and Ethylacetoacetat (13), sowie einige weitere Transformationsprodukte, isomere 5-Methylsubstituierte 1,2,4-Triazolo[1,5-a]pyrimidine sind (1,9,11).相似文献
16.
Changes of the rheological properties of hyaluronic acid (sodium-magnesium salt) solutions after exposure to UV radiation
indicate a vigorous decrease in their viscosity, but its still strong shear rate dependence. Whereas the presence of the singlet
oxygen sensitizer (anthracene-1-sulphonic acid) brings about a loss of shear dependence; the studied solutions show newtonian
behavior. 相似文献
17.
In this paper the Agmon-Miranda maximum principle for solutions of strongly elliptic differential equations Lu = 0 in a bounded domain G with a conical point is considered. Necessary and sufficient conditions for the validity of this principle are given both for smooth solutions of the equation Lu = 0 in G and for the generalized solution of the problem Lu = 0 in G, D
k
v
u = gk on G (k = 0,...,m-1). It will be shown that for every elliptic operator L of order 2m > 2 there exists such a cone in n (n4) that the Agmon-Miranda maximum principle fails in this cone. 相似文献
18.
This work describes the use of a dual-standard analysis approach termed the time-average ratio (TAR) in affinity capillary electrophoresis (ACE) to estimate binding constants of receptors to ligands. In this form of analysis the TAR is the migration time of the receptor divided by the average of the sum of the migration times of two non-interacting standards. This change in TAR as a function of the concentration of ligand yields a value for the binding constant. This concept is demonstrated using three model systems: carbonic anhydrase B (CAB, EC 4.2.1.1) and arylsulfonamides, vancomycin (Van) and ristocetin (Rist) from Streptomyces orientalis and Nocardia lurida, respectively, and d-Ala- d-Ala terminus peptides. Three ACE techniques are used to examine the three systems: standard ACE, flow-through partial-filling ACE (FTPFACE), and on-column derivatization coupled to ACE. The findings described here demonstrate that ACE data analyzed using the TAR form of analysis yield binding constants between receptors and ligands comparable to those estimated using other ACE forms of analysis. A comparison to three other forms of analysis is described. 相似文献
19.
Bin-Long Sun Ying-Ying Wang Sen Yang Min-Ting Tu Ying-Ying Shao Yi Hua Yi Zhou Cheng-Xia Tan 《Molecules (Basel, Switzerland)》2022,27(12)
To develop new compounds with high activity, broad spectrum and low-toxicity, 17 benzamides substituted with quinoline-linked 1,2,4-oxadiazole were designed using the splicing principle of active substructures and were synthesized. The biological activities were evaluated against 10 fungi, indicating that some of the synthetic compounds showed excellent fungicidal activities. For example, at 50 mg/L, the inhibitory activity of 13p (3-Cl-4-Cl substituted, 86.1%) against Sclerotinia sclerotiorum was superior to that of quinoxyfen (77.8%), and the inhibitory activity of 13f (3-CF3 substituted, 77.8%) was comparable to that of quinoxyfen. The fungicidal activities of 13f and 13p to Sclerotinia sclerotiorum were better than that of quinoxyfen (14.19 mg/L), with EC50 of 6.67 mg/L and 5.17 mg/L, respectively. Furthermore, the acute toxicity of 13p was 19.42 mg/L, classifying it as a low-toxic compound. 相似文献
20.
自1921年成立至今中国共产党已经走过了一百年的辉煌历程。以人民为中心、为人民谋利益、与时俱进地解决中国人民的生存和发展(即民生)问题是中国共产党人的初心使命和矢志不渝的追求。社会政策作为国家解决民生问题的制度化举措自中国共产党成立以来一直受到关注和重视,但在中国革命、建设和改革等不同历史时期党对社会政策角色的运用会根据时代的特点、具体国情的变化、解决民生方针策略的需要做出调整和改变。建党百年来中国共产党解决民生问题按路径划分大致经历了三个阶段,在不同阶段党对社会政策角色的运用会发生相应的变化:党的成立至新中国成立前系党为解决民生问题创造政治前提阶段,社会政策被作为政治动员的重要手段(1921−1949);新中国成立至1978年系党为解决民生问题创造经济前提(基础)阶段,社会政策依附经济体制,服务于经济发展(1949−1978);改革开放以来系党在中国特色社会主义市场经济条件下为解决效率与公平的矛盾不断加大保障和改善民生的力度、民生事业不断取得新的进步阶段,社会政策相对独立发展,其地位和作用不断强化(1978年至今)。建党百年来党对社会政策的探索提供了丰富的经验和启示,对其加以科学总结具有重要的理论和现实意义。 相似文献