全文获取类型
收费全文 | 208篇 |
免费 | 0篇 |
专业分类
系统科学 | 1篇 |
现状及发展 | 148篇 |
研究方法 | 7篇 |
综合类 | 52篇 |
出版年
2012年 | 8篇 |
2011年 | 7篇 |
2010年 | 3篇 |
2008年 | 3篇 |
2007年 | 6篇 |
2006年 | 5篇 |
2005年 | 2篇 |
2004年 | 6篇 |
2003年 | 4篇 |
2002年 | 7篇 |
1999年 | 2篇 |
1991年 | 2篇 |
1990年 | 3篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1986年 | 3篇 |
1985年 | 7篇 |
1984年 | 5篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1981年 | 5篇 |
1980年 | 4篇 |
1979年 | 3篇 |
1978年 | 5篇 |
1977年 | 6篇 |
1976年 | 5篇 |
1975年 | 3篇 |
1973年 | 8篇 |
1972年 | 7篇 |
1971年 | 10篇 |
1970年 | 3篇 |
1969年 | 6篇 |
1968年 | 3篇 |
1967年 | 7篇 |
1966年 | 6篇 |
1965年 | 6篇 |
1964年 | 2篇 |
1963年 | 3篇 |
1962年 | 5篇 |
1961年 | 4篇 |
1960年 | 2篇 |
1959年 | 1篇 |
1958年 | 4篇 |
1957年 | 3篇 |
1955年 | 2篇 |
1954年 | 2篇 |
1948年 | 1篇 |
1947年 | 1篇 |
1946年 | 1篇 |
1945年 | 4篇 |
排序方式: 共有208条查询结果,搜索用时 15 毫秒
1.
Dina C Meyre D Gallina S Durand E Körner A Jacobson P Carlsson LM Kiess W Vatin V Lecoeur C Delplanque J Vaillant E Pattou F Ruiz J Weill J Levy-Marchal C Horber F Potoczna N Hercberg S Le Stunff C Bougnères P Kovacs P Marre M Balkau B Cauchi S Chèvre JC Froguel P 《Nature genetics》2007,39(6):724-726
We identified a set of SNPs in the first intron of the FTO (fat mass and obesity associated) gene on chromosome 16q12.2 that is consistently strongly associated with early-onset and severe obesity in both adults and children of European ancestry with an experiment-wise P value of 1.67 x 10(-26) in 2,900 affected individuals and 5,100 controls. The at-risk haplotype yields a proportion of attributable risk of 22% for common obesity. We conclude that FTO contributes to human obesity and hence may be a target for subsequent functional analyses. 相似文献
2.
Radu I Vahaplar K Stamm C Kachel T Pontius N Dürr HA Ostler TA Barker J Evans RF Chantrell RW Tsukamoto A Itoh A Kirilyuk A Rasing T Kimel AV 《Nature》2011,472(7342):205-208
Ferromagnetic or antiferromagnetic spin ordering is governed by the exchange interaction, the strongest force in magnetism. Understanding spin dynamics in magnetic materials is an issue of crucial importance for progress in information processing and recording technology. Usually the dynamics are studied by observing the collective response of exchange-coupled spins, that is, spin resonances, after an external perturbation by a pulse of magnetic field, current or light. The periods of the corresponding resonances range from one nanosecond for ferromagnets down to one picosecond for antiferromagnets. However, virtually nothing is known about the behaviour of spins in a magnetic material after being excited on a timescale faster than that corresponding to the exchange interaction (10-100?fs), that is, in a non-adiabatic way. Here we use the element-specific technique X-ray magnetic circular dichroism to study spin reversal in GdFeCo that is optically excited on a timescale pertinent to the characteristic time of the exchange interaction between Gd and Fe spins. We unexpectedly find that the ultrafast spin reversal in this material, where spins are coupled antiferromagnetically, occurs by way of a transient ferromagnetic-like state. Following the optical excitation, the net magnetizations of the Gd and Fe sublattices rapidly collapse, switch their direction and rebuild their net magnetic moments at substantially different timescales; the net magnetic moment of the Gd sublattice is found to reverse within 1.5 picoseconds, which is substantially slower than the Fe reversal time of 300 femtoseconds. Consequently, a transient state characterized by a temporary parallel alignment of the net Gd and Fe moments emerges, despite their ground-state antiferromagnetic coupling. These surprising observations, supported by atomistic simulations, provide a concept for the possibility of manipulating magnetic order on the timescale of the exchange interaction. 相似文献
3.
4.
A coat subunit of Golgi-derived non-clathrin-coated vesicles with homology to the clathrin-coated vesicle coat protein beta-adaptin 总被引:76,自引:0,他引:76
T Serafini G Stenbeck A Brecht F Lottspeich L Orci J E Rothman F T Wieland 《Nature》1991,349(6306):215-220
Four high-molecular-weight proteins form the main subunits of the coat of Golgi-derived (non-clathrin) coated vesicles. One of these coat proteins, beta-COP, is identical to a Golgi-associated protein of relative mass 110,000 (110K) that shares homology with the adaptin proteins of clathrin-coated vesicles. This connection, and the comparable molecular weights of the coat proteins of Golgi-derived and clathrin-coated vesicles, indicates that they may be structurally related. The identification of beta-COP as the 110K protein explains the blocking of secretion by the drug brefeldin A. 相似文献
5.
6.
7.
H. Eaulstich M. Bloching S. Zobeley Th Wieland 《Cellular and molecular life sciences : CMLS》1973,29(10):1230-1232
Zusammenfassung Die Cottoneffekte der Amanitine konnten dem Indolteil bzw. den Amidgruppen des Molekühls zugeordnet werden. Das untoxische Amanullin besitzt die gleiche Konformation wie die toxischen Peptide, das untoxische Aldoamanitin dagegen eine andere. Die absolute Konfiguration der Sulfoxidgruppe der Amatoxine ist identisch mit der des toxischen Phalloidinsulfoxids.
Part 43 of the series: Components of the green deathcap toadstoolAmanita phalloides. Part 42:F. Fahrenholz, H. Faulstich andTh. Wieland, Liebigs Annln Chem.743, 83 (1971).
Acknowledgment. The authors wish to express their gratitude toDr. A. Buku for preparation of methyl--aldoamanitin. 相似文献
Part 43 of the series: Components of the green deathcap toadstoolAmanita phalloides. Part 42:F. Fahrenholz, H. Faulstich andTh. Wieland, Liebigs Annln Chem.743, 83 (1971).
Acknowledgment. The authors wish to express their gratitude toDr. A. Buku for preparation of methyl--aldoamanitin. 相似文献
8.
van Boekel R Min M Leinert Ch Waters LB Richichi A Chesneau O Dominik C Jaffe W Dutrey A Graser U Henning T de Jong J Köhler R de Koter A Lopez B Malbet F Morel S Paresce F Perrin G Preibisch T Przygodda F Schöller M Wittkowski M 《Nature》2004,432(7016):479-482
Our Solar System was formed from a cloud of gas and dust. Most of the dust mass is contained in amorphous silicates, yet crystalline silicates are abundant throughout the Solar System, reflecting the thermal and chemical alteration of solids during planet formation. (Even primitive bodies such as comets contain crystalline silicates.) Little is known about the evolution of the dust that forms Earth-like planets. Here we report spatially resolved detections and compositional analyses of these building blocks in the innermost two astronomical units of three proto-planetary disks. We find the dust in these regions to be highly crystallized, more so than any other dust observed in young stars until now. In addition, the outer region of one star has equal amounts of pyroxene and olivine, whereas the inner regions are dominated by olivine. The spectral shape of the inner-disk spectra shows surprising similarity with Solar System comets. Radial-mixing models naturally explain this resemblance as well as the gradient in chemical composition. Our observations imply that silicates crystallize before any terrestrial planets are formed, consistent with the composition of meteorites in the Solar System. 相似文献
9.
Tschöp M Castañeda TR Joost HG Thöne-Reineke C Ortmann S Klaus S Hagan MM Chandler PC Oswald KD Benoit SC Seeley RJ Kinzig KP Moran TH Beck-sickinger AG Koglin N Rodgers RJ Blundell JE Ishii Y Beattie AH Holch P Allison DB Raun K Madsen K Wulff BS Stidsen CE Birringer M Kreuzer OJ Schindler M Arndt K Rudolf K Mark M Deng XY Whitcomb DC Halem H Taylor J Dong J Datta R Culler M Craney S Flora D Smiley D Heiman ML Withcomb DC 《Nature》2004,430(6996):1 p following 165; discussion 2 p following 165
Batterham et al. report that the gut peptide hormone PYY3-36 decreases food intake and body-weight gain in rodents, a discovery that has been heralded as potentially offering a new therapy for obesity. However, we have been unable to replicate their results. Although the reasons for this discrepancy remain undetermined, an effective anti-obesity drug ultimately must produce its effects across a range of situations. The fact that the findings of Batterham et al. cannot easily be replicated calls into question the potential value of an anti-obesity approach that is based on administration of PYY3-36. 相似文献
10.
Novel aspects and new roles for the serine protease plasmin 总被引:5,自引:0,他引:5
The serine protease plasmin is distributed throughout the human body in the form of the zymogen plasminogen. The plasminogen activation system is mostly recognized for its fibrinolytic activity but is also upregulated in chronic inflammatory diseases, including atherosclerosis and arthritis. Plasmin can bind to a variety of cells, including monocytes, through low-affinity binding sites and triggers aggregation of neutrophils, platelet degranulation and arachidonate release from endothelial cells. In monocytes, plasmin elicits full-scale proinflammatory activation, including lipid mediator release, chemotaxis and cytokine expression, as well as induction of other proinflammatory genes. The effects of plasmin are specific, require the active catalytic center and can be antagonized by lysine analogues, implying binding of the plasmin molecule to the cell membrane through its lysine binding sites. In view of the upregulation of the fibrinolytic genes in chronic inflammatory diseases, cell activation by plasmin is likely to play a major pathophysiological role, a view that is further supported by data from transgenic mice.Received 9 September 2003; received after revision 4 October 2003; accepted 13 October 2003 相似文献