全文获取类型
收费全文 | 286篇 |
免费 | 4篇 |
国内免费 | 1篇 |
专业分类
系统科学 | 1篇 |
理论与方法论 | 10篇 |
现状及发展 | 93篇 |
研究方法 | 60篇 |
综合类 | 117篇 |
自然研究 | 10篇 |
出版年
2020年 | 3篇 |
2019年 | 1篇 |
2018年 | 8篇 |
2017年 | 6篇 |
2016年 | 7篇 |
2015年 | 10篇 |
2014年 | 1篇 |
2013年 | 7篇 |
2012年 | 20篇 |
2011年 | 22篇 |
2010年 | 10篇 |
2009年 | 4篇 |
2008年 | 26篇 |
2007年 | 19篇 |
2006年 | 25篇 |
2005年 | 18篇 |
2004年 | 13篇 |
2003年 | 13篇 |
2002年 | 9篇 |
2001年 | 7篇 |
2000年 | 5篇 |
1999年 | 1篇 |
1998年 | 5篇 |
1995年 | 2篇 |
1994年 | 1篇 |
1991年 | 1篇 |
1988年 | 3篇 |
1985年 | 2篇 |
1983年 | 1篇 |
1982年 | 3篇 |
1981年 | 2篇 |
1980年 | 1篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1977年 | 5篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1974年 | 3篇 |
1973年 | 2篇 |
1972年 | 4篇 |
1971年 | 2篇 |
1970年 | 3篇 |
1969年 | 6篇 |
1968年 | 1篇 |
1967年 | 1篇 |
1966年 | 1篇 |
1954年 | 1篇 |
排序方式: 共有291条查询结果,搜索用时 0 毫秒
171.
Stuart PE Nair RP Ellinghaus E Ding J Tejasvi T Gudjonsson JE Li Y Weidinger S Eberlein B Gieger C Wichmann HE Kunz M Ike R Krueger GG Bowcock AM Mrowietz U Lim HW Voorhees JJ Abecasis GR Weichenthal M Franke A Rahman P Gladman DD Elder JT 《Nature genetics》2010,42(11):1000-1004
We carried out a meta-analysis of two recent psoriasis genome-wide association studies with a combined discovery sample of 1,831 affected individuals (cases) and 2,546 controls. One hundred and two loci selected based on P value rankings were followed up in a three-stage replication study including 4,064 cases and 4,685 controls from Michigan, Toronto, Newfoundland and Germany. In the combined meta-analysis, we identified three new susceptibility loci, including one at NOS2 (rs4795067, combined P = 4 × 10?11), one at FBXL19 (rs10782001, combined P = 9 × 10?1?) and one near PSMA6-NFKBIA (rs12586317, combined P = 2 × 10??). All three loci were also associated with psoriatic arthritis (rs4795067, combined P = 1 × 10??; rs10782001, combined P = 4 × 10??; and rs12586317, combined P = 6 × 1??) and purely cutaneous psoriasis (rs4795067, combined P = 1 × 10??; rs10782001, combined P = 2 × 10??; and rs12586317, combined P = 1 × 10??). We also replicated a recently identified association signal near RNF114 (rs495337, combined P = 2 × 10??). 相似文献
172.
173.
Takeda Y Costa S Delamarre E Roncal C Leite de Oliveira R Squadrito ML Finisguerra V Deschoemaeker S Bruyère F Wenes M Hamm A Serneels J Magat J Bhattacharyya T Anisimov A Jordan BF Alitalo K Maxwell P Gallez B Zhuang ZW Saito Y Simons M De Palma M Mazzone M 《Nature》2011,479(7371):122-126
PHD2 serves as an oxygen sensor that rescues blood supply by regulating vessel formation and shape in case of oxygen shortage. However, it is unknown whether PHD2 can influence arteriogenesis. Here we studied the role of PHD2 in collateral artery growth by using hindlimb ischaemia as a model, a process that compensates for the lack of blood flow in case of major arterial occlusion. We show that Phd2 (also known as Egln1) haplodeficient (Phd2(+/-)) mice displayed preformed collateral arteries that preserved limb perfusion and prevented tissue necrosis in ischaemia. Improved arteriogenesis in Phd2(+/-) mice was due to an expansion of tissue-resident, M2-like macrophages and their increased release of arteriogenic factors, leading to enhanced smooth muscle cell (SMC) recruitment and growth. Both chronic and acute deletion of one Phd2 allele in macrophages was sufficient to skew their polarization towards a pro-arteriogenic phenotype. Mechanistically, collateral vessel preconditioning relied on the activation of canonical NF-κB pathway in Phd2(+/-) macrophages. These results unravel how PHD2 regulates arteriogenesis and artery homeostasis by controlling a specific differentiation state in macrophages and suggest new treatment options for ischaemic disorders. 相似文献
174.
Caffau E Bonifacio P François P Sbordone L Monaco L Spite M Spite F Ludwig HG Cayrel R Zaggia S Hammer F Randich S Molaro P Hill V 《Nature》2011,477(7362):67-69
The early Universe had a chemical composition consisting of hydrogen, helium and traces of lithium; almost all other elements were subsequently created in stars and supernovae. The mass fraction of elements more massive than helium, Z, is known as 'metallicity'. A number of very metal-poor stars has been found, some of which have a low iron abundance but are rich in carbon, nitrogen and oxygen. For theoretical reasons and because of an observed absence of stars with Z?1.5?×?10(-5), it has been suggested that low-mass stars cannot form from the primitive interstellar medium until it has been enriched above a critical value of Z, estimated to lie in the range 1.5?×?10(-8) to 1.5?×?10(-6) (ref. 8), although competing theories claiming the contrary do exist. (We use 'low-mass' here to mean a stellar mass of less than 0.8 solar masses, the stars that survive to the present day.) Here we report the chemical composition of a star in the Galactic halo with a very low Z (≤?6.9?×?10(-7), which is 4.5?×?10(-5) times that of the Sun) and a chemical pattern typical of classical extremely metal-poor stars--that is, without enrichment of carbon, nitrogen and oxygen. This shows that low-mass stars can be formed at very low metallicity, that is, below the critical value of Z. Lithium is not detected, suggesting a low-metallicity extension of the previously observed trend in lithium depletion. Such lithium depletion implies that the stellar material must have experienced temperatures above two million kelvin in its history, given that this is necessary to destroy lithium. 相似文献
175.
176.
177.
178.
Bernard Colin François Dubeau Hussein Khreibani Jules de Tibeiro 《Journal of Classification》2013,30(3):453-473
Based on the notion of mutual information between the components of a random vector, we construct, for data reduction reasons, an optimal quantization of the support of its probability measure. More precisely, we propose a simultaneous discretization of the whole set of the components of the random vector which takes into account, as much as possible, the stochastic dependence between them. Examples are presented. 相似文献
179.
Fran?ois Bavaud 《Journal of Classification》2011,28(3):297-314
The class of Schoenberg transformations, embedding Euclidean distances into higher dimensional Euclidean spaces, is presented, and derived from theorems on positive definite and conditionally negative definite matrices. Original results on the arc lengths, angles and curvature of the transformations are proposed, and visualized on artificial data sets by classical multidimensional scaling. A distance-based discriminant algorithm and a robust multidimensional centroid estimate illustrate the theory, closely connected to the Gaussian kernels of Machine Learning. 相似文献
180.
Rosy El Ramy Najat Magroun Nadia Messadecq Laurent R. Gauthier François D. Boussin Ullas Kolthur-Seetharam Valérie Schreiber Michael W. McBurney Paolo Sassone-Corsi Françoise Dantzer 《Cellular and molecular life sciences : CMLS》2009,66(19):3219-3234
Poly(ADP-ribose) polymerase-1 (Parp-1) and the protein deacetylase SirT1 are two of the most effective NAD+-consuming enzymes in the cell with key functions in genome integrity and chromatin-based pathways. Here, we examined the
in vivo crosstalk between both proteins. We observed that the double disruption of both genes in mice tends to increase late
post-natal lethality before weaning consistent with important roles of both proteins in genome integrity during mouse development.
We identified increased spontaneous telomeric abnormalities associated with decreased cell growth in the absence of either
SirT1 or SirT1 and Parp-1 in mouse cells. In contrast, the additional disruption of Parp-1 rescued the abnormal pericentric
heterochromatin, the nucleolar disorganization and the mitotic defects observed in SirT1-deficient cells. Together, these
findings are in favor of key functions of both proteins in cellular response to DNA damage and in the modulation of histone
modifications associated with constitutive heterochromatin integrity. 相似文献