全文获取类型
收费全文 | 115篇 |
免费 | 0篇 |
专业分类
系统科学 | 1篇 |
理论与方法论 | 2篇 |
现状及发展 | 59篇 |
研究方法 | 14篇 |
综合类 | 39篇 |
出版年
2018年 | 2篇 |
2017年 | 1篇 |
2015年 | 1篇 |
2013年 | 1篇 |
2012年 | 6篇 |
2011年 | 8篇 |
2009年 | 2篇 |
2008年 | 6篇 |
2007年 | 1篇 |
2006年 | 3篇 |
2005年 | 5篇 |
2004年 | 4篇 |
2003年 | 3篇 |
2002年 | 5篇 |
2001年 | 4篇 |
2000年 | 1篇 |
1999年 | 1篇 |
1992年 | 4篇 |
1991年 | 1篇 |
1990年 | 2篇 |
1987年 | 3篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1979年 | 4篇 |
1978年 | 2篇 |
1975年 | 6篇 |
1974年 | 11篇 |
1973年 | 4篇 |
1972年 | 2篇 |
1970年 | 3篇 |
1969年 | 5篇 |
1968年 | 2篇 |
1966年 | 3篇 |
1962年 | 1篇 |
1960年 | 1篇 |
1957年 | 1篇 |
1956年 | 1篇 |
1954年 | 2篇 |
排序方式: 共有115条查询结果,搜索用时 78 毫秒
11.
12.
Head JW Neukum G Jaumann R Hiesinger H Hauber E Carr M Masson P Foing B Hoffmann H Kreslavsky M Werner S Milkovich S van Gasselt S;HRSC Co-Investigator Team 《Nature》2005,434(7031):346-351
Images from the Mars Express HRSC (High-Resolution Stereo Camera) of debris aprons at the base of massifs in eastern Hellas reveal numerous concentrically ridged lobate and pitted features and related evidence of extremely ice-rich glacier-like viscous flow and sublimation. Together with new evidence for recent ice-rich rock glaciers at the base of the Olympus Mons scarp superposed on larger Late Amazonian debris-covered piedmont glaciers, we interpret these deposits as evidence for geologically recent and recurring glacial activity in tropical and mid-latitude regions of Mars during periods of increased spin-axis obliquity when polar ice was mobilized and redeposited in microenvironments at lower latitudes. The data indicate that abundant residual ice probably remains in these deposits and that these records of geologically recent climate changes are accessible to future automated and human surface exploration. 相似文献
13.
Poulet F Bibring JP Mustard JF Gendrin A Mangold N Langevin Y Arvidson RE Gondet B Gomez C Berthé M Erard S Forni O Manaud N Poulleau G Soufflot A Combes M Drossart P Encrenaz T Fouchet T Melchiorri R Bellucci G Altieri F Formisano V Fonti S Capaccioni F Cerroni P Coradini A Korablev O Kottsov V Ignatiev N Titov D Zasova L Pinet P Schmitt B Sotin C Hauber E Hoffmann H Jaumann R Keller U Forget F;Omega Team 《Nature》2005,438(7068):623-627
The recent identification of large deposits of sulphates by remote sensing and in situ observations has been considered evidence of the past presence of liquid water on Mars. Here we report the unambiguous detection of diverse phyllosilicates, a family of aqueous alteration products, on the basis of observations by the OMEGA imaging spectrometer on board the Mars Express spacecraft. These minerals are mainly associated with Noachian outcrops, which is consistent with an early active hydrological system, sustaining the long-term contact of igneous minerals with liquid water. We infer that the two main families of hydrated alteration products detected-phyllosilicates and sulphates--result from different formation processes. These occurred during two distinct climatic episodes: an early Noachian Mars, resulting in the formation of hydrated silicates, followed by a more acidic environment, in which sulphates formed. 相似文献
14.
15.
Melatonin stimulates growth of brown adipose tissue 总被引:4,自引:0,他引:4
16.
Orton GS Yanamandra-Fisher PA Fisher BM Friedson AJ Parrish PD Nelson JF Bauermeister AS Fletcher L Gezari DY Varosi F Tokunaga AT Caldwell J Baines KH Hora JL Ressler ME Fujiyoshi T Fuse T Hagopian H Martin TZ Bergstralh JT Howett C Hoffmann WF Deutsch LK Van Cleve JE Noe E Adams JD Kassis M Tollestrup E 《Nature》2008,453(7192):196-199
Observations of oscillations of temperature and wind in planetary atmospheres provide a means of generalizing models for atmospheric dynamics in a diverse set of planets in the Solar System and elsewhere. An equatorial oscillation similar to one in the Earth's atmosphere has been discovered in Jupiter. Here we report the existence of similar oscillations in Saturn's atmosphere, from an analysis of over two decades of spatially resolved observations of its 7.8-microm methane and 12.2-microm ethane stratospheric emissions, where we compare zonal-mean stratospheric brightness temperatures at planetographic latitudes of 3.6 degrees and 15.5 degrees in both the northern and the southern hemispheres. These results support the interpretation of vertical and meridional variability of temperatures in Saturn's stratosphere as a manifestation of a wave phenomenon similar to that on the Earth and in Jupiter. The period of this oscillation is 14.8 +/- 1.2 terrestrial years, roughly half of Saturn's year, suggesting the influence of seasonal forcing, as is the case with the Earth's semi-annual oscillation. 相似文献
17.
A defined range of guard cell calcium oscillation parameters encodes stomatal movements. 总被引:59,自引:0,他引:59
G J Allen S P Chu C L Harrington K Schumacher T Hoffmann Y Y Tang E Grill J I Schroeder 《Nature》2001,411(6841):1053-1057
Oscillations in cytosolic calcium concentration ([Ca2+]cyt) are central regulators of signal transduction cascades, although the roles of individual [Ca2+]cyt oscillation parameters in regulating downstream physiological responses remain largely unknown. In plants, guard cells integrate environmental and endogenous signals to regulate the aperture of stomatal pores and [Ca2+]cyt oscillations are a fundamental component of stomatal closure. Here we systematically vary [Ca2+]cyt oscillation parameters in Arabidopsis guard cells using a 'calcium clamp' and show that [Ca2+]cyt controls stomatal closure by two mechanisms. Short-term 'calcium-reactive' closure occurred rapidly when [Ca2+]cyt was elevated, whereas the degree of long-term steady-state closure was 'calcium programmed' by [Ca2+]cyt oscillations within a defined range of frequency, transient number, duration and amplitude. Furthermore, in guard cells of the gca2 mutant, [Ca2+]cyt oscillations induced by abscisic acid and extracellular calcium had increased frequencies and reduced transient duration, and steady-state stomatal closure was abolished. Experimentally imposing [Ca2+]cyt oscillations with parameters that elicited closure in the wild type restored long-term closure in gca2 stomata. These data show that a defined window of guard cell [Ca2+]cyt oscillation parameters programs changes in steady-state stomatal aperture. 相似文献
18.
Chasman DI Schürks M Anttila V de Vries B Schminke U Launer LJ Terwindt GM van den Maagdenberg AM Fendrich K Völzke H Ernst F Griffiths LR Buring JE Kallela M Freilinger T Kubisch C Ridker PM Palotie A Ferrari MD Hoffmann W Zee RY Kurth T 《Nature genetics》2011,43(7):695-698
Migraine is a common, heterogeneous and heritable neurological disorder. Its pathophysiology is incompletely understood, and its genetic influences at the population level are unknown. In a population-based genome-wide analysis including 5,122 migraineurs and 18,108 non-migraineurs, rs2651899 (1p36.32, PRDM16), rs10166942 (2q37.1, TRPM8) and rs11172113 (12q13.3, LRP1) were among the top seven associations (P < 5 × 10(-6)) with migraine. These SNPs were significant in a meta-analysis among three replication cohorts and met genome-wide significance in a meta-analysis combining the discovery and replication cohorts (rs2651899, odds ratio (OR) = 1.11, P = 3.8 × 10(-9); rs10166942, OR = 0.85, P = 5.5 × 10(-12); and rs11172113, OR = 0.90, P = 4.3 × 10(-9)). The associations at rs2651899 and rs10166942 were specific for migraine compared with non-migraine headache. None of the three SNP associations was preferential for migraine with aura or without aura, nor were any associations specific for migraine features. TRPM8 has been the focus of neuropathic pain models, whereas LRP1 modulates neuronal glutamate signaling, plausibly linking both genes to migraine pathophysiology. 相似文献
19.
Dobbins SE Broderick P Melin B Feychting M Johansen C Andersson U Brännström T Schramm J Olver B Lloyd A Ma YP Hosking FJ Lönn S Ahlbom A Henriksson R Schoemaker MJ Hepworth SJ Hoffmann P Mühleisen TW Nöthen MM Moebus S Eisele L Kosteljanetz M Muir K Swerdlow A Simon M Houlston RS 《Nature genetics》2011,43(9):825-827
To identify susceptibility loci for meningioma, we conducted a genome-wide association study of 859 affected individuals (cases) and 704 controls with validation in two independent sample sets totaling 774 cases and 1,764 controls. We identified a new susceptibility locus for meningioma at 10p12.31 (MLLT10, rs11012732, odds ratio = 1.46, P(combined) = 1.88 × 10(-14)). This finding advances our understanding of the genetic basis of meningioma development. 相似文献
20.
Crystal structure of TFIID TATA-box binding protein. 总被引:48,自引:0,他引:48
D B Nikolov S H Hu J Lin A Gasch A Hoffmann M Horikoshi N H Chua R G Roeder S K Burley 《Nature》1992,360(6399):40-46