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排序方式: 共有1103条查询结果,搜索用时 15 毫秒
91.
Sam Schellens Cynthia Lenaerts María del Rocío Prez Baca Dorien Cools Paulien Peeters Elisabeth Marchal Jozef Vanden Broeck 《International journal of molecular sciences》2022,23(16)
Ecdysteroids are widely investigated for their role during the molting cascade in insects; however, they are also involved in the development of the female reproductive system. Ecdysteroids are synthesized from cholesterol, which is further converted via a series of enzymatic steps into the main molting hormone, 20-hydoxyecdysone. Most of these biosynthetic conversion steps involve the activity of cytochrome P450 (CYP) hydroxylases, which are encoded by the Halloween genes. Three of these genes, spook (spo), phantom (phm) and shade (shd), were previously characterized in the desert locust, Schistocerca gregaria. Based on recent sequencing data, we have now identified the sequences of disembodied (dib) and shadow (sad), for which we also analyzed spatiotemporal expression profiles using qRT-PCR. Furthermore, we investigated the possible role(s) of five different Halloween genes in the oogenesis process by means of RNA interference mediated knockdown experiments. Our results showed that depleting the expression of SchgrSpo, SchgrSad and SchgrShd had a significant impact on oocyte development, oviposition and hatching of the eggs. Moreover, the shape of the growing oocytes, as well as the deposited eggs, was very drastically altered by the experimental treatments. Consequently, it can be proposed that these three enzymes play an important role in oogenesis. 相似文献
92.
93.
The use of bovine rumen protein (raw and extruded) as a replacement for extruded soy protein concentrate in three meat products (pork sausage, chicken hamburger, and kibbe) was investigated. Similarity between rumen and soy protein meat products was assessed using triangle tests and sensory acceptability evaluated by consumer panelists using a nine-point hedonic scale. The addition of raw rumen protein was detected in all meat product types tested, while extruded rumen protein was only detected in kibbe. The addition of raw rumen protein decreased the acceptability of pork sausage aroma and flavor, but improved kibbe appearance, texture and overall acceptability. The addition of extruded rumen protein reduced the acceptability of chicken hamburger texture, but improved pork sausage flavor. Replacement of soy protein by bovine rumen protein is feasible based upon sensory results, but depended upon its form and the type of meat product to which it was added. 相似文献
94.
Multicentric Castleman''s disease in HIV infection: a clinical and pathological study of 20 patients
E Oksenhendler M Duarte J Soulier P Cacoub Y Welker J Cadranel D Cazals-Hatem B Autran JP Clauvel M Raphael 《Canadian Metallurgical Quarterly》1996,10(1):61-67
Techniques of transcatheter device placement for treatment of pediatric congenital heart disease have developed substantially since their introduction 20 years ago. Patent ductus arteriosus occlusion can be accomplished by umbrella deployment or coil placement. Intracardiac defects can be closed with umbrella or buttoned devices. Stenoses of vessels or conduits that are only temporarily relieved with balloon dilation can be effectively expanded with intravascular stents. Recent procedural modifications have been introduced in an attempt to minimize the size of the delivery sheath and reduce complications that can arise from device embolization. Transcatheter device placement can be an important adjunct to surgery for correction or palliation of congenital heart lesions. 相似文献
95.
The major objective of the present study was to examine whether approach versus avoidance commitment to one's intimate relationship was differentially predictive of relationship quality parameters in the long run. In the 1st testing period, 134 participants (67 romantic couples) answered questions about approach- versus avoidance-related measures. Commitment and relationship quality parameters such as satisfaction and emotions depending on the partner's presence were assessed in all 3 testing periods. The proposed distinction between an approach and an avoidance type of commitment was validated through correlations with other approach- versus avoidance-related measures. Longitudinal analyses revealed that approach commitment predicted relationship quality parameters positively, whereas avoidance commitment predicted them negatively. The results are discussed in terms of the benefit of an approach-avoidance-based conceptualization of commitment. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
96.
Species richness, structural diversity and species composition in meadows created by visitors of a botanical garden in Switzerland 总被引:3,自引:0,他引:3
Biodiversity is an increasingly important criterion in designing ecological compensation areas and urban green areas. However, little is known about how important biodiversity is to the general public. This paper presents the results of two complementary studies investigating the meadow preferences of visitors to a botanical garden in Switzerland. In the first study, 152 people were asked to create their own favourite meadow patch by selecting 25 out of 779 local wild plants (54 species) that were displayed in flowerpots. In the second study, 143 people were asked with the help of a written questionnaire to imagine a bare piece of land the size of 100 m × 100 m close to their place of living and mentally create the meadow of their dreams. In both cases, study participants assembled meadows that were species-rich and rich in structural diversity (expressed by plant height and leaf forms). Moreover, they explicitly stated diversity as their main assemblage criterion. Although study participants favoured plants with large or colourful flowers, only a third of all plants in the meadows created with real plants were flowering and in people's imagined meadows grasses were frequently included, indicating that people like diverse meadows consisting of a green matrix with some colourful flowers. 相似文献
97.
Probability of infancy problems for space launch vehicles 总被引:3,自引:1,他引:2
Seth D. Guikema M. Elisabeth Pat-Cornell 《Reliability Engineering & System Safety》2005,87(3):303-314
This paper addresses the treatment of ‘infancy problems’ in the reliability analysis of space launch systems. To that effect, we analyze the probability of failure of launch vehicles in their first five launches. We present methods and results based on a combination of Bayesian probability and frequentist statistics designed to estimate the system's reliability before the realization of a large number of launches. We show that while both approaches are beneficial, the Bayesian method is particularly useful when the experience base is small (i.e. for a new rocket). We define reliability as the probability of success based on a binary failure/no failure event. We conclude that the mean failure rates appear to be higher in the first and second flights (≈1/3 and 1/4, respectively) than in subsequent ones (third, fourth and fifth), and Bayesian methods do suggest that there is indeed some difference in launch risk over the first five launches. Yet, based on a classical frequentist analysis, we find that for these first few flights, the differences in the mean failure rates over successive launches or over successive generations of vehicles, are not statistically significant (i.e. do not meet a 95% confidence level). This is true because the frequentist analysis is based on a fixed confidence level (here: 95%), whereas the Bayesian one allows more flexibility in the conclusions based on a full probability density distribution of the failure rate and therefore, permits better interpretation of the information contained in a small sample. The approach also gives more insight into the considerable uncertainty in failure rate estimates based on small sample sizes. 相似文献
98.
99.
Influence of avocado oil processing on the nature of some unsaponifiable constituents 总被引:2,自引:0,他引:2
M. Farines J. Soulier A. Rancurel M. G. Montaudoin L. Leborgne 《Journal of the American Oil Chemists' Society》1995,72(4):473-476
The unsaponifiable part of avocado pear oil, after heating during extraction and processing, contains an abundant fraction
that has never been found in the unsaponifiable part of usual vegetable oils nor in cold-pressed avocado oil. Nine components
were detected. Eight of them could be identified through chromatographic fractionations and spectroscopic analysis, mainly
by mass spectrometry and proton nuclear magnetic resonance. These products are characterized by a homogeneous structure. A
furyl nucleus is substituted in position 2 by an aliphatic, mono- or polyunsaturated chain. The chainlength varies from 13
to 17 carbon atoms. The carbon number is always odd. The significance of these components in the biological effects of avocado
oil unsaponifiables is still being studied. 相似文献
100.
Elisabeth Paté-Cornell 《Fire Technology》1995,31(2):99-119
The offshore oil platform Piper Alpha was destroyed in July 1988 by a catastrophic fire. The causes of the accident included a combination of technical and organizational factors. In this paper, I describe the accident, its chronology, and the dependencies involved. I then examine some of the human errors that led to the disaster and their organizational roots, such as economic pressures, the permit-to-work system, and the inadequacy of regulatory oversight in the United Kingdom at the time of the accident. Risk-reduction measures can be costly, however, and priorities must be set based on costs and benefits. To this end, I describe a probabilistic risk analysis model that can be used to assess the benefits of different fire safety measures, focusing on reinforcing the emergency water pumps. 相似文献