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51.
Tara Sinclair Herman O. Stekler Hans Christian Muller‐Droge 《Journal of forecasting》2016,35(6):493-503
In this paper we explore methodologies appropriate for evaluating a forecasting competition when the participants predict a number of variables that may be related to each other and are judged for a single period. Typically, forecasting competitions are judged on a variable‐by‐variable basis, but a multivariate analysis is required to determine how each competitor performed overall. We use three different multivariate tests to determine an overall winner for a forecasting competition for the German economy across 25 different institutions for a single time period using a vector of eight key economic variables. We find that neglecting the cross‐variable relationships greatly alters the outcome of the forecasting competition. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
52.
Exercise-induced BCL2-regulated autophagy is required for muscle glucose homeostasis 总被引:3,自引:0,他引:3
He C Bassik MC Moresi V Sun K Wei Y Zou Z An Z Loh J Fisher J Sun Q Korsmeyer S Packer M May HI Hill JA Virgin HW Gilpin C Xiao G Bassel-Duby R Scherer PE Levine B 《Nature》2012,481(7382):511-515
Exercise has beneficial effects on human health, including protection against metabolic disorders such as diabetes. However, the cellular mechanisms underlying these effects are incompletely understood. The lysosomal degradation pathway, autophagy, is an intracellular recycling system that functions during basal conditions in organelle and protein quality control. During stress, increased levels of autophagy permit cells to adapt to changing nutritional and energy demands through protein catabolism. Moreover, in animal models, autophagy protects against diseases such as cancer, neurodegenerative disorders, infections, inflammatory diseases, ageing and insulin resistance. Here we show that acute exercise induces autophagy in skeletal and cardiac muscle of fed mice. To investigate the role of exercise-mediated autophagy in vivo, we generated mutant mice that show normal levels of basal autophagy but are deficient in stimulus (exercise- or starvation)-induced autophagy. These mice (termed BCL2 AAA mice) contain knock-in mutations in BCL2 phosphorylation sites (Thr69Ala, Ser70Ala and Ser84Ala) that prevent stimulus-induced disruption of the BCL2-beclin-1 complex and autophagy activation. BCL2 AAA mice show decreased endurance and altered glucose metabolism during acute exercise, as well as impaired chronic exercise-mediated protection against high-fat-diet-induced glucose intolerance. Thus, exercise induces autophagy, BCL2 is a crucial regulator of exercise- (and starvation)-induced autophagy in vivo, and autophagy induction may contribute to the beneficial metabolic effects of exercise. 相似文献
53.
There are large amounts of heavy alpha-emitters in nuclear waste and nuclear materials inventories stored in various sites around the world. These include plutonium and minor actinides such as americium and curium. In preparation for geological disposal there is consensus that actinides that have been separated from spent nuclear fuel should be immobilized within mineral-based ceramics rather than glass because of their superior aqueous durability and lower risk of accidental criticality. However, in the long term, the alpha-decay taking place in these ceramics will severely disrupt their crystalline structure and reduce their durability. A fundamental property in predicting cumulative radiation damage is the number of atoms permanently displaced per alpha-decay. At present, this number is estimated to be 1,000-2,000 atoms/alpha in zircon. Here we report nuclear magnetic resonance, spin-counting experiments that measure close to 5,000 atoms/alpha in radiation-damaged natural zircons. New radiological nuclear magnetic resonance measurements on highly radioactive, 239Pu zircon show damage similar to that caused by 238U and 232Th in mineral zircons at the same dose, indicating no significant effect of half-life or loading levels (dose rate). On the basis of these measurements, the initially crystalline structure of a 10 weight per cent 239Pu zircon would be amorphous after only 1,400 years in a geological repository (desired immobilization timescales are of the order of 250,000 years). These measurements establish a basis for assessing the long-term structural durability of actinide-containing ceramics in terms of an atomistic understanding of the fundamental damage event. 相似文献
54.
Summary Adult Monarch butterflies injected with3H-juvenile hormone (JH) showed a significant increase in haemolymph JH metabolites after a 40 min flight compared to unflown controls. In addition, haemolymph enzymatic JH metabolism was shown to increase with thoracic temperature increases previously shown to be associated with flight.We thank Paul Cherubini for supplying California Monarchs, Dr L.I. Gilbert for his helpful suggestions, Jeanne Whitaker for secretarial assistance, and Henry Lessman for aid in insect culture. 相似文献
55.
本文提出了一种确定Jacob?—Cowperthwaite—Zwisler状态方程单组分当量分子阱深?和σ的改进方法。此法用调整爆炸产物比热比的方法代替降低化学能方法,从而使确定单组分当量值的方法得到了显著改进。奥克托金炸药爆炸产物的单组分当量值已被精确地求得,并与TIGER编码的结果取得一致。这种单组分当量JCZ方程首先被用于燃烧转爆轰模型研究。它对奥克托金炸药的C—J特性给出了足够精确的预测。 相似文献
56.
Summary The monarch butterfly loses sensitivity to the posteclosion diuretic hormone of this species within 12 h of eclosion. This de-sensitization can be accelerated by exposure to the diuretic hormone, and decelerated by both hormone deficiency and reduced temperature. 相似文献
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Plant degradation: a nematode expansin acting on plants 总被引:3,自引:0,他引:3
Qin L Kudla U Roze EH Goverse A Popeijus H Nieuwland J Overmars H Jones JT Schots A Smant G Bakker J Helder J 《Nature》2004,427(6969):30
Expansin proteins, which have so far been identified only in plants, rapidly induce extension of plant cell walls by weakening the non-covalent interactions that help to maintain their integrity. Here we show that an animal, the plant-parasitic roundworm Globodera rostochiensis, can also produce a functional expansin, which it uses to loosen cell walls when invading its host plant. As this nematode is known to be able to disrupt covalent bonds in plant cell walls, its accompanying ability to loosen non-covalent bonds challenges the prevailing view that animals are genetically poorly equipped to degrade plant cell walls. 相似文献