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1.
AIMS AND SCOPE     
The Journal of Bionic Engineering publishes original research papers and reviews on all aspects of bionic science and engineering including fundamental understandings of animals and plants for bionic engineering, such as locomotion and behaviors of animals, structures, composites, morphology and physical properties of plants and natural materials, applications of such understandings in engineering, technology and designs.  相似文献   

2.
One of the highest-ranking journals In biology with an Impact factor of 6.787! BioEssays Editor: Adam S. Wilkins, Cambridge, UK BioEssays offers readers in-depth review articles and serves as a resource for education and new ideas by exploring a wide range of biological topics. Researchers and teachers are presented with a unique tool for learning how findings in molecular, cellular,  相似文献   

3.
PartlissubdividedintotWollthofaed,Whichcomrisefluvial-lacustrinandfissure-cavemlahons'Fluvial-laCUStrinetritSdopoaitalinthelowerpartoftheriverchannels,basinsorplain;fissare-cavendbotSexPondonlyinthemountaintriin,wherePartIisabout5-8mmickandharsmammalfotalsSUchasbooridaefeen'etrp.indot.),MbonasP.,lycbotessineasis,cfMthechtai,FelissP-,Archhaplandna,Cervche,andColubdee'ItmaybeconsideredtobeearlyPleistocene'Partnismorethan2OInmick'ThefadesofPartIIcomrisealluvial-laCUStrineandfise-caved…  相似文献   

4.
The expression “universal base” is very often used to express hybridization properties and recognition patterns of nucleosides. Their behaviour in biological applications, however, is of great interest regarding, e.g., their incorporation by polymerases. The 4,6-difluorobenzimidazole and the 2,4-difluorobenzene nucleoside analogues have proven to be universal bases that do not discriminate between the four natural nucleobases in RNA duplexes. Therefore, we synthesized the corresponding triphosphates to evaluate their behavior in polymerase catalyzed reactions and to investigate their ability to serve as substrates for the T7 RNA polymerase.  相似文献   

5.
Novel D- and L-2′-azido-2′,3′-dideoxy-4′-thionucleosides were synthesized starting from L- and D-xylose via D- and L-4-thioarabitol derivative as key intermediates and evaluated for antiviral activity, respectively. When the final nucleosides were tested against HIV-1, HSV-1, HSV-2, and HCMV, they were found to be only active against HCMV without cytotoxicity up to 100 μg/ml.  相似文献   

6.
A series of novel, unusual type of acyclic phosphonate-based nucleotide analogues related to well-known antivirals (PMEA and HPMPA) was synthesized using easily available synthon. These compounds, which are distinguished for the presence of phosphonomethyl acetal linkage, form a group of derivatives that contribute to the understanding of structure-activity relationship within the area of acyclic nucleotide analogues.  相似文献   

7.
N4-Acetyl-1-(2, 3-di-O-acetyl-4-thio-β-D-arabinofuranosyl)cytosine (2) was synthesized in three steps from 1-(4-thio-β-D-arabinofuranosyl)cytosine (1). The reaction of this partially blocked 4′-thio-ara-C derivative 2 with 2-chloro-4H-1,3,2-benzodioxaphosphorin-4-one gave the 5′-phosphitylate derivative 3, which on reaction with pyrophosphate gave the 5′-nucleosidylcyclotriphosphite 4. Product 4 was then oxidized with iodine/pyridine/water and deblocked with concentrated ammonium hydroxide to provide the desired 4′-thio-ara-C-5′-triphosphate 5. This triphosphate 5 was converted to 4′-thio-ara-C -5′-monophosphate 6 by treatment with snake venom phosphodiesterase I. The details of the synthesis, purification, and characterization of both nucleotides are described.  相似文献   

8.
Our view of sperm competition is largely shaped by game-theoretic models based on external fertilizers. External fertilization is of particular interest as it is the ancestral mode of reproduction and as such, relevant to the evolution and maintenance of anisogamy (i.e., large eggs and tiny, numerous sperm). Current game-theoretic models have been invaluable in generating predictions of male responses to sperm competition in a range of internal fertilizers but these models are less relevant to marine broadcast spawners, the most common and archetypal external fertilizers. Broadcast spawners typically have incomplete fertilization due to sperm limitation and/or polyspermy (too many sperm), but the effects of incomplete (<100% fertilization rates) fertilization on game-theoretic predictions are unclear particular with regards to polyspermy. We show that incorporating the effects of sperm concentration on fertilization success changes the predictions of a classic game-theoretic model, dramatically reversing the relationship between sperm competition and the evolutionarily stable sperm release strategy. Furthermore, our results suggest that male and female broadcast spawners are likely to be in conflict at both ends of the sperm environment continuum rather than only in conditions of excess sperm as previously thought. Across the majority of the parameter space we explored, males release either too little to too much sperm for females to achieve complete fertilization. This conflict could result in a coevolutionary race that may have led to the evolution of internal fertilization in marine organisms.  相似文献   

9.
Choosing from whom to learn is an important element of social learning. It affects learner success and the profile of behaviors in the population. Because individuals often differ in their traits and capabilities, their benefits from different behaviors may also vary. Homophily, or assortment, the tendency of individuals to interact with other individuals with similar traits, is known to affect the spread of behaviors in humans. We introduce models to study the evolution of assortative social learning (ASL), where assorting on a trait acts as an individual‐specific mechanism for filtering relevant models from which to learn when that trait varies. We show that when the trait is polymorphic, ASL may maintain a stable behavioral polymorphism within a population (independently of coexistence with individual learning in a population). We explore the evolution of ASL when assortment is based on a nonheritable or partially heritable trait, and when ASL competes with different non‐ASL strategies: oblique (learning from the parental generation) and vertical (learning from the parent). We suggest that the tendency to assort may be advantageous in the context of social learning, and that ASL might be an important concept for the evolutionary theory of social learning.  相似文献   

10.
ABSTRACT

Computers are available that can store, synthesize and replay sounds using digital technology. I describe the major components of audio computers, the principles of digital sound acquisition and playback, and information and caveats for scientists interested in acquiring an audio computer system for their own use. A tutorial on analog filter application is also included as well as a diagnostic procedure and a buyer's check list.  相似文献   

11.
12.
Synthesis of Z and E ethenyl acyclonucleosides (6a-e and 7a-e) via Michael addition of nucleobases with the diethyl acetylenedicarboxylate is described. The structures of compounds have been confirmed by spectral data. New compounds were found to be inactive against DNA and RNA viruses.  相似文献   

13.
Reproductive and early life-history traits can be considered aspects of either offspring or maternal phenotype, and their evolution will therefore depend on selection operating through offspring and maternal components of fitness. Furthermore, selection at these levels may be antagonistic, with optimal offspring and maternal fitness occurring at different phenotypic values. We examined selection regimes on the correlated traits of birth weight, birth date, and litter size in Soay sheep (Ovis aries) using data from a long-term study of a free-living population on the archipelago of St. Kilda, Scotland. We tested the hypothesis that selective constraints on the evolution of the multivariate phenotype arise through antagonistic selection, either acting at offspring and maternal levels, or on correlated aspects of phenotype. All three traits were found to be under selection through variance in short-term and lifetime measures of fitness. Analysis of lifetime fitness revealed strong positive directional selection on birth weight and weaker selection for increased birth date at both levels. However, there was also evidence for stabilizing selection on these traits at the maternal level, with reduced fitness at high phenotypic values indicating lower phenotypic optima for mothers than for offspring. Additionally, antagonistic selection was found on litter size. From the offspring's point of view it is better to be born a singleton, whereas maternal fitness increases with average litter size. The decreased fitness of twins is caused by their reduced birth weight; therefore, this antagonistic selection likely results from trade-offs between litter size and birth weight that have different optimal resolutions with respect to offspring and maternal fitness. Our results highlight how selection regimes may vary depending on the assignment of reproductive and early life-history traits to either offspring or maternal phenotype.  相似文献   

14.
Protecting confidentiality is an essential value in all human relationships, no less in medical practice and research.(1) Doctor-patient and researcher-participant relationships are built on trust and on the understanding those patients' secrets will not be disclosed.(2) However, this confidentiality can be breached in some situations where it is necessary to meet a strong conflicting duty.(3) Confidentiality, in a general sense, has received much interest in Islamic resources including the Qur'an, Sunnah and juristic writings. However, medical and research confidentiality have not been explored deeply. There are few fatwas about the issue, despite an increased effort by both individuals and Islamic medical organizations to use these institutional fatwas in their research. Infringements on confidentiality make up a significant portion of institutional fatwas, yet they have never been thoroughly investigated. Moreover, the efforts of organizations and authors in this regard still require further exploration, especially on the issue of research confidentiality. In this article, we explore medical and research confidentiality and potential conflicts with this practice as a result of fatwas released by international, regional, and national Islamic Sunni juristic councils. We discuss how these fatwas affect research and publication by Muslim doctors, researchers, and Islamic medical organizations. We argue that more specialized fatwas are needed to clarify Islamic juristic views about medical and research confidentiality, especially the circumstances in which infringements on this confidentiality are justified.  相似文献   

15.
16.
1. The variation of the experimental values (R (ω)), (C (ω)) of the resistance and capacity of blood for increasing frequencies is approximately represented by the equation: See PDF for Equation in which R o and C o are the resistance and capacity of the blood at low frequency and See PDF for Equation is the resistance of the blood at infinite frequency. Formulæ (1) and (2) are derived by considering the blood as equivalent to the system shown in the diagram (a) of Fig. 1. 2. By the application of formula (1) to our experimental data the value of R(∞) can be extrapolated with high accuracy. R(∞) represents the resistance) which would have been obtained at low frequency, if the membranes around the corpuscles could have been removed. 3. The specific resistance of the corpuscle interior can be calculated by equation (5), using experimental values for R(∞), for the volume concentration of the blood and for the specific resistance of the serum. 4. The specific resistance of the interior of the red corpuscle of the calf is found to be 3.5 ± 10 per cent times the specific resistance of the serum.  相似文献   

17.
A suitably protected 4-C-hydroxymethyl-arabino-pentofuranose was prepared and condensed with the following nucleobases: uracil, 5-fluorouracil and thymine. The corresponding cytosine and 5-fluorocytosine derivatives have also been obtained respectively from the uracil and 5-fluorouracil nucleosides. Separation of the anomeric mixtures followed by deprotection afforded the target compounds that were found to be non-cytotoxic to CCRF-CEM leukemia cells.  相似文献   

18.
A great deal of folklore, superstition and emotional reaction is attached to the common cold, but established objective information is quite limited. The evidence concerning etiology, epidemiology, physiology, prevention and treatment of the common cold is briefly summarized and critically evaluated. There is disappointing lack of real progress in any of these aspects of the common cold problem.  相似文献   

19.
Repellent and oviposition deterrent activities of the essential oil from Mikania micrantha and five volatile compounds including limonene, a-terpinene, linalool, B-caryophylene and verbenone on the diamondback moth (DBM), Plutella xylostella, was investigated in door and in net-house. The results showed that the essential oil of the M. micrantha had significant repellant effect (at flow 100-180 mL/min) and oviposition deterrent activity at dose 1020 uL/seedling for the DBM. In five volatile compounds, a-terpinene, limonene and linalool had significant effect on repellent and oviposition deterrent of the DBM moths, but verbenone and B-caryophylene, no significantly effect was observed in repellent and oviposition deterrent.  相似文献   

20.
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