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排序方式: 共有312条查询结果,搜索用时 15 毫秒
11.
Lipid and fatty acyl composition of rat brain capillary endothelia isolated by a new technique 总被引:7,自引:0,他引:7
A method is described for the isolation of pure capillary endothelia from rat brain and the phospholipid composition of these
cells is reported. This method is rapid and requires only a small amount of starting material. It involves: (a) tissue disruption
by high speed homogenization, (b) separation of the capillary endothelia from other brain structures using sucrose gradients,
and (c) a final purification using a glass bead column. Choline and ethanolamine phosphoglycerides were found to be the predominant
lipid classes of these cells amounting to 31.9% and 24.4%, respectively, of total phospholipids. The choline phosphoglycerides
consisted almost exclusively of 1,2-diacyl glycerophosphorylcholine, whereas the ethanolamine phosphoglycerides consisted
of approximately equal amounts of 1,2-diacyl and 1-alk-l’-enyl-2-acyl glycerophosphorylethanolamine. The composition of the
constituent fatty acids of both choline and ethanolamine phosphoglycerides and the alk-1-enyl composition of ethanolamine
phosphoglycerides is reported. Saturated fatty acids accounted for 45% of the total fatty acids in choline phosphoglycerides
and for 53% in ethanolamine phosphoglycerides. Arachidonic acid accounted for approximately 48% of the total fatty acids in
alk-1-enyl ethanolamine phosphoglyceride. 相似文献
12.
13.
Cyanogenic glycosides (CNGs) act as feeding or oviposition deterrents and are toxic after enzymatic hydrolysis, thus negatively affecting herbivore performance. While most studies on CNGs focus on leaf herbivores, here we examined seeds from natural populations of Phaseolus lunatus in Mexico. The predominant CNGs, linamarin and lotaustralin, were quantified for each population by using ultra-high pressure liquid chromatography-mass spectrometry. We also examined whether there was a correlation between the concentration of CNGs and the performance of the Mexican bean beetle, Zabrotes subfasciatus, on seeds from each population. The concentrations of CNGs in the seeds were relatively high compared to the leaves and were significantly variable among populations. Surprisingly, this had little effect on the performance of the bruchid beetles. Zabrotes subfasciatus can tolerate high concentrations of CNGs, most likely because of the limited β-glucosidase activity in the seeds. Seed herbivory does not appear to liberate hydrogen cyanide due to the low water content in the seed. This study illustrates the importance of quantifying the natural variation and activity of toxic compounds in order to make relevant biological inferences about their role in defense against herbivores. 相似文献
14.
Benítez B Archile A Rangel L Bracho M Hernández M Márquez E 《Archivos latinoamericanos de nutrición》2002,52(3):307-312
The purpose of this research was to evaluate the nutritional quality and acceptability of a meat product formulated with mechanically deboned poultry meat (40%), bovine plasma (40%) and bovine red cells (3%) as major ingredients. Proteins, fat, humidity and ash were determined by AOAC procedure, iron and calcium by Atomic Absorption Spectrometry and essential amino acids by HPLC. Biological evaluation was performed using digestibility and PER procedures. To evaluate the acceptability (flavor, color and odor) of the product were used 277 children. Results indicated that 100 g of the formulated meat product contain 10.7 g of proteins, 4.4 g of fat, 68.6 g of humidity, 2.9 g of ash, 4.9 mg of iron, 46.6 mg of calcium. Essential amino acids are above the FAO requirements for a highly nutritional protein digestibility (92.4%) and PER (2.18). Acceptability was 91.3% for flavor, 81.2% for color and 92.4% for odor. The high nutritional quality and acceptability along with the low cost make this meat product suitable for government social programs. 相似文献
15.
Pun BK Wu SY Seigneur C Seinfeld JH Griffin RJ Pandis SN 《Environmental science & technology》2003,37(16):3647-3661
The formation of secondary organic aerosols (SOA) is simulated for the Nashville/western Tennessee domain using three recent SOA modules incorporated into the three-dimensional air quality model, CMAQ. The Odum/Griffin et al. and CMU/STI modules represent SOA absorptive partitioning into a mixture of primary and secondary particulate organic compounds (OC), with some differences in the formulation of the absorption process and the selection of SOA species and their precursors. Empirical representations based on measured laboratory SOA yields are used for condensable organic products in both these modules. The AEC module simulates SOA absorption into organic and aqueous particulate phases, and a representation based on an explicit gas-phase mechanism is used in the AEC module. Predicted SOA concentrations can vary by a factor of 10 or more. In general, the gas-phase mechanistic approach predicts a higher yield of SOA than those based on laboratory yields. There exist some differences in the two empirical modules despite their similar basis on experimental data. All three modules predict a dominance of SOA of biogenic origin as compared to SOA of anthropogenic origin. The causes for differences among the three SOA modules include the representation of terpenes, the mechanistic versus empirical representation of SOA-forming reactions, the identities of SOA, and the parameters used in the gas/particle partitioning calculations. Two sensitivity studies show that formation of water-soluble SOA and temperature dependence may be areas of key uncertainties affecting current models. 相似文献
16.
Blanchard Ray; Steiner Betty W.; Clemmensen Leonard H. 《Canadian Metallurgical Quarterly》1985,53(3):295
Conducted 2 studies of gender dysphoria and postoperative adjustment by transsexuals. Study 1 examined the relation of gender reorientation (approximation of the status of the opposite biological sex) to psychological adjustment in gender dysphorics. Three S groups (75 heterosexual males, mean age 36.7 yrs; 85 homosexual males, mean age 29.8 yrs; and 103 biological females, mean age 27.4 yrs) were studied in multiple regression analyses, with psychological symptoms as criteria and measures of 3 roughly sequential components of gender reorientation (role changes, document changes, and physical changes), age, and education as predictors. Psychological complaints correlated negatively with the earliest phase of reorientation for females and with the later phases for males. Age and education bore little relation to current symptoms. Results suggest that psychological improvement accompanies gender reorientation in both male and female gender dysphorics; the greatest degree of improvement is seen earlier in the process for females. Ss in Study 2 were postoperative transsexuals (32 homosexual males, mean age 33.2 yrs; 9 heterosexual males, mean age 47.7 yrs; and 38 biological females, mean age 32.6 yrs) at least 1 yr after surgery. Follow-up rate was 77.5% for all Ss meeting the 1-yr criterion. Satisfaction with surgery was high, and psychosocial adjustment was acceptable for the majority. Results of both studies support the rationale for clinical intervention in aid of gender reorientation in selected cases. (18 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
17.
Rui Wang Betty Salzberg David Lomet 《The VLDB Journal The International Journal on Very Large Data Bases》2011,20(3):347-370
Providing enterprises with reliable and available Web-based application programs is a challenge. Applications are traditionally
spread over multiple nodes, from user (client), to middle tier servers, to back end transaction systems, e.g. databases. It
has proven very difficult to ensure that these applications persist across system crashes so that “exactly once” execution
is produced, always important and sometimes essential, e.g., in the financial area. Our system provides a framework for exactly
once execution of multi-tier Web applications, built on a commercially available Web infrastructure. Its capabilities include
low logging overhead, recovery isolation (independence), and consistency between mid-tier and transactional back end. Good
application performance is enabled via persistent shared state in the middle tier while providing for private session state
as well. Our extensive experiments confirm both the desired properties and the good performance. 相似文献
18.
Sylvia Chan Yannis Chan Giulia Foscari Alain Fouraux Alexander Giarlis Ekaterina Golovatyuk Inge Goudsmit Ravi Kamisetti Michael Kokora Barend Koolhaas Janice Kwok Katja Lam Michelle Lam Jedidiah Lau Miranda Lee Brigitta Lenz Brendan McGetrick Betty Ng Stephan Petermann Roberto Requejo Benny Tam 《城市环境设计》2014,(6):70-73
正OMA发展西九文化区,必须面对一项挑战:将一个盛载政府极大抱负,以及持分者多元利益的超大型多用途项目,转化成一个既有趣又严肃、既有规划又允许即兴、既中国化又国际化的文化区。这个文化区规模庞大,但不失亲密融洽的感觉;富地标性,但十分谦和;容易理解,却能带来惊喜。为避免造成过分冲击,OMA采纳了一种每个香港市民都熟悉的建筑类型作为方案的发展 相似文献
19.
Presents an obituary for Robert Bruce Ammons. Ammons was a researcher, professor, and founder of Perceptual and Motor Skills and Psychological Reports. He dedicated his life to encouraging scientific originality. He was a licensed clinician, a fellow of the American Association for the Advancement of Science, Sigma Xi, and several divisions of the American Psychological Association (Experimental Psychology, Experimental Analysis of Behavior, Clinical Psychology, and History of Psychology), and he was a member of more than 30 national and international professional organizations. He held numerous offices in the Montana Psychological Association from 1958 to 1985, including being the president and secretary of the Montana Psychological Association's Internal Certification Board. His teaching centered on the history of psychology as a modern science, the psychology of the scientist, techniques of research strategy and theory construction, child development, and aesthetics. Ammons passed away in 1999. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
20.