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BACKGROUND: The PubMed database contains nearly 15 million references from more than 4,800 biomedical journals. In general, authors of scientific articles are addressed by their last name and forename initial. DISCUSSION: In general, names can be too common and not unique enough to be search criteria. Today, Ph.D. students, other researchers and women publish scientific work. A person may not only have one name but several names and publish under each name. A Unique Scientist ID could help to address people in peer-to-peer (P2P) networks. As a starting point, perhaps PubMed could generate and manage such a scientist ID. SUMMARY: A Unique Scientist ID would improve knowledge management in science. Unfortunately in some of the publications, and then within the online databases, only one letter abbreviates the author's forename. A common name with only one initial could retrieve pertinent citations, but include many false drops (retrieval matching searched criteria but indisputably irrelevant).  相似文献   

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A search of the genomic sequences of the thermophilic microorganisms Aquifex aeolicus, Archaeoglobus fulgidus, Methanobacterium thermoautotrophicum, and Methanococcus jannaschii for the first seven enzymes (aroG, B, D, E, K, A, and C ) involved in the shikimic acid biosynthetic pathway reveal two key enzymes are missing. The first enzyme in the pathway, 3-deoxy-d-arabino-heptulosonic acid 7-phosphate synthase (aroG) and the second enzyme in the pathway, 5-dehydroquinic acid synthase (aroB) are "missing." The remaining five genes for the shikimate pathway in these organism are present and are similar to the corresponding Escherichia coli genes. The genomic sequences of the thermophiles Pyrococcus abyssi and Thermotoga maritima contain the aroG and aroB genes. Several fungi such as Aspergillus fumigatus, Aspergillus nidulans, Saccharomyces cerevisiae, Schizosaccharomyces pombe, Pneumocystis carinii f. sp. carinii, and Neurospora crassa contain the gene aroM, a pentafunctional enzyme whose overall activity is equivalent to the combined catalytic activities of proteins expressed by aroB, D, E, K, and A genes. Two of these fungi also lack an aroG gene. A discussion of potential reasons for these missing enzymes is presented.  相似文献   

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Studies of cranial differences between modern humans and Neandertals have identified several characteristics for which the two groups differ in their mean values, the proportional relationships with other traits, or both. However, the limited number of fairly complete Neandertals has hindered investigations into patterns of integration – covariance and correlation among traits – in this fossil group. Here, we use multiple approaches specifically designed to deal with fragmentary fossils to test if metric cranial traits in Neandertals fit modern human patterns of integration. Based on 37 traits collected from a sample of 2524 modern humans from Howells’ data set and 20 Neandertals, we show that overall patterns of cranial integration are significantly different between Neandertals and modern humans. However, at the same time, Neandertals are consistent with a modern human pattern of integration for more than three-quarters of the traits. Additionally, the differences between the predicted and actual values for the deviating traits are rather small, indicating that the differences in integration are subtle. Traits for which Neandertals deviate from modern human integration patterns tend to be found in regions where Neandertals and modern humans are known to also differ in their mean values. We conclude that the evolution of patterns of cranial integration is a cause for caution but also presents an opportunity for understanding cranial differences between modern humans and Neandertals.  相似文献   

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Do Unique Proteins Exist in Taste Buds?   总被引:2,自引:1,他引:1  
Proteins in papillae on the bovine tongue were analyzed by semi-micro, polyacrylamide gel electrophoresis. All the proteins in the papillae with taste buds were observed to be common to proteins in the surrounding epithelium without taste buds. The protein band which was reported to form a weak complex with compounds called sweet by man was also found in all parts of the tongue epithelium. The receptor molecules for chemical stimuli may be distributed in all the cells of the tongue epithelium or the content of receptor molecules in taste bud papillae may be extremely low.  相似文献   

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Are the Tastes of Polycose and Monosodium Glutamate Unique?   总被引:2,自引:2,他引:0  
To study whether Polycose and monosodium L-glutamate (L-MSG)have unique tastes differing from the traditional four basictastes, chemosensory profiles were established for Polycose,L-MSG and a group of related compounds (sucrose, maltose, monosodiumD-glutamate (D-MSG), sodium chloride, calcium chloride). Flavourswere assessed using whole-mouth tests in human subjects withnose open or clamped to reduce olfactory input. Polycose (amixture of glucose-based oligosaccharides) had a flavor consistingof an olfactory component and a maltose-like taste. L-MSG andD-MSG profiles differed from each other, and from NaCl and CaCl2.L-MSG had a lower threshold and a higher frequency of ‘other’tastes than the D form. The data do not support a ‘polysaccharide’taste, but suggest a chiral receptor site for ‘umami’taste. Chem. Senses 21: 341–347, 1996.  相似文献   

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Electroencephalographic (EEG) recordings from 19 scalp recording sites were used to differentiate among two posited unique forms of mediation, concentration and mindfulness, and a normal relaxation control condition. Analyzes of all traditional frequency bandwidth data (i.e., delta 1–3 Hz; theta, 4–7 Hz; alpha, 8–12 Hz; beta 1, 13–25 Hz; beta 2, 26–32 Hz) showed strong mean amplitude frequency differences between the two meditation conditions and relaxation over numerous cortical sites. Furthermore, significant differences were obtained between concentration and mindfulness states at all bandwidths. Taken together, our results suggest that concentration and mindfulness meditations may be unique forms of consciousness and are not merely degrees of a state of relaxation.  相似文献   

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Research concerning various types of auctions, such as English auctions, Dutch auctions, highest-price sealed-bid auctions, and second-price sealed-bid auctions, is always a topic of considerable interest in interdisciplinary fields. The type of auction, known as a lowest unique bid auction (LUBA), has also attracted significant attention. Various models have been proposed, but they often fail to explain satisfactorily the real bid-distribution characteristics. This paper discusses LUBA bid-distribution characteristics, including the inverted-J shape and the exponential decrease in the upper region. The authors note that this type of distribution, which initially increases and later decreases, cannot be derived from the symmetric Nash equilibrium framework based on perfect information that has previously been used. A novel optimization model based on non-perfect information is presented. The kernel of this model is the premise that agents make decisions to achieve maximum profit based on imaginary information or assumptions regarding the behavior of others.  相似文献   

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All students of xylem structure–function relations need to be familiar with the work of Sherwin Carlquist. He studies xylem through the lens of the comparative method, which uses the appearance of similar anatomical features under similar conditions of natural selection to infer function. “Function” in biology implies adaptation; maximally supported adaptation inferences require experimental and comparative xylem scientists to work with one another. Engaging with comparative inferences of xylem function will, more likely sooner rather than later, bring one to the work of Sherwin Carlquist. To mark his 90th birthday, I highlight just a few examples of his extraordinarily perceptive and general comparative insights. One is “Carlquist’s Law”, the pervasive tendency for vessels to be solitary when background cells are conductive. I cover his pioneering of “ecological” wood anatomy, viewing xylem variation as reflecting the effects of selection across climate and habit variation. Another is the embolism vulnerability–conduit diameter relationship, one of the most widely invoked structure–function relationships in xylem biology. I discuss the inferential richness within the notion of Carlquistian paedomorphosis, including detailed functional inferences regarding ray cell orientation. My final example comes from his very recent work offering the first satisfactory hypothesis accounting for the geographical and histological distribution of scalariform perforation plates as an adaptation, including “Carlquist’s Ratchet”, why scalariform plates are adaptive but do not re-evolve once lost. This extraordinarily rich production over six decades is filled with comparative inferences that should keep students of xylem function busy testing for decades to come.  相似文献   

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This paper investigated the role of acetylcholine (ACh) in physiological regulation of amylase secretion in avian exocrine pancreas. In the isolated duck pancreatic acini, ACh dose dependently stimulated amylase secretion, with a maximal effective concentration at 10 μM. The cAMP-mobilizing compounds forskolin, vasoactive intestinal peptide (VIP)/pituitary adenylate cyclase activating peptide (PACAP) receptor (VPAC) agonists PACAP-38 and PACAP-27 had no effect on the dose–response curve. ACh dose dependently induced increases in cytosolic Ca2+ concentration ([Ca2+] c ), with increasing concentrations transforming oscillations into plateau increases. Forskolin (10 μM), PACAP-38 (1 nM), PACAP-27 (1 nM), or VIP (10 nM) alone did not stimulate [Ca2+] c increase; neither did they modulate ACh-induced oscillations, nor made ACh low concentration effective. These data indicate that ACh-stimulated zymogen secretion in duck pancreatic acinar cells is not subject to modulation from the cAMP signaling pathway; whereas it has been widely reported in the rodents that ACh-stimulated exocrine pancreatic secretion is significantly enhanced by cAMP-mobilizing agents. This makes the duck exocrine pancreas unique in that cholinergic stimulus-secretion coupling is not subject to cAMP regulation.  相似文献   

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Does the photosynthetic light‐acclimation need change in leaf anatomy?   总被引:23,自引:3,他引:20  
There is a strong correlation between leaf thickness and the light‐saturated rate of photosynthesis per unit leaf area (Pmax). However, when leaves are exposed to higher light intensities after maturation, Pmax often increases without increasing leaf thickness. To elucidate the mechanism with which mature leaves increase Pmax, the change in anatomical and physiological characteristics of mature leaves of Chenopodium album, which was transferred from low to high light condition, were examined. When compared with leaves subjected to low light continuously (LL leaves), the leaves transferred from low to high light (LH leaves) significantly increased Pmax. The transfer also increased the area of chloroplasts facing the intercellular space (Sc) and maintained a strong correlation between Pmax and Sc. The mesophyll cells of LL leaves had open spaces along cell walls where chloroplasts were absent, which enabled the leaves to increase Pmax when they were exposed to high light (LH). However, the LH leaves were not thick enough to allow further increase in Pmax to the level in HH leaves. Thus leaf thickness determines an upper limit of Pmax of leaves subjected to a change from low to high light conditions. Shade leaves would only increase Pmax when they have open space to accommodate chloroplasts which elongate after light conditions improve.  相似文献   

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Arkadiusz Sołtysiak 《HOMO》2012,63(2):110-113
Dental caries is an infectious disease caused by oral acidophilic bacteria feeding on fermentable sugars, e.g. Streptococcus mutans. The frequency of dental caries in Neandertals was very low. This was usually explained as the result of a low-sugar diet. Recent research, however, revealed some regional differences between European and Near Eastern Neandertals, with the latter consuming considerable amounts of plants including highly cariogenic dates. This discovery, compared with the results of research on genetic diversity of S. mutans, may suggest that this species, and perhaps other most virulent species, were absent in the oral flora of Neandertals.  相似文献   

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The hypocotyl of viviparous seedlings of mangrove Rhizophoraceae (tribe Rhizophoreae) has a common suite of anatomical features but a range of anatomical structures that may be diagnostic at the generic or even specific level. This information is summarized in the form of a dichotomous key. A common and previously unreported anatomical feature is the presence of tension wood fibres developed eccentrically in secondary xylem at the distal pole of seedlings grown in both artificial and natural conditions. These fibres are apparently the source of the mechanism whereby an initially horizontal seedling becomes erected rapidly once it is rooted distally, even though this appears to be achieved at a considerable mechanical disadvantage. The morphological result is a distinct 'hook' at the distal end of the established seedling. This mechanism allows rapid erection of a horizontally stranded seedling, such that the plumule is raised, snorkel-like, above immediate tidal influence. This may be necessary, since gas exchange through the surface of the seedling is not possible via the thick, cutinized and stomata-free epidermis of the hypocotyl. We suggest that the need to produce an elongated propagule, with this self-erecting capability favours the evolution of vivipary in these plants because it permits the earliest development of the plumule in air rather than water. The suitability of mangrove seedlings for further experimental and anatomical study is emphasized. The study also exemplifies how anatomy can be placed in a dynamic context.  相似文献   

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Tena Thau 《Bioethics》2020,34(7):638-644
In fascinating recent work, some philosophers have argued that it would be morally permissible and prudentially rational to sign up for cryonics—if you can afford the price tag of the procedure. In this paper I ask: why not share the elixir of extended life with everyone? Should governments financially support, positively encourage, or even require people to undergo cryonics? From a general principle of beneficence, I construct a formal argument for cryonics promotion policies. I consider the objection that a subset of these policies would violate autonomy, but I argue that—to the contrary—considerations of autonomy weigh in their favour. I then consider objections based on cost and population, but argue that neither is fatal. Finally, I raise the objection that I believe poses the most serious challenge: that those who revive the cryonically preserved might inflict suffering upon them.  相似文献   

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So far, no compelling scientific evidence has been found to suggest that the consumption of transgenic or genetically modified (GM) plants by animals or humans is more likely to cause harm than is the consumption of their conventional counterparts. Despite this lack of scientific evidence, the economic prospects for GM plants are probably limited in the short term and there is public opposition to the technology. Now is a good time to address several issues concerning GM plants, including the potential for transgenes to migrate from GM plants to gut microbes or to animal or human tissues, the consequences of consuming GM crops, either as fresh plants or as silage, and the problems caused by current legislation on GM labelling and beyond.  相似文献   

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