全文获取类型
收费全文 | 10904篇 |
免费 | 59篇 |
国内免费 | 105篇 |
专业分类
系统科学 | 240篇 |
丛书文集 | 679篇 |
教育与普及 | 569篇 |
理论与方法论 | 29篇 |
现状及发展 | 897篇 |
研究方法 | 1232篇 |
综合类 | 7413篇 |
自然研究 | 9篇 |
出版年
2017年 | 14篇 |
2016年 | 11篇 |
2015年 | 17篇 |
2014年 | 28篇 |
2013年 | 24篇 |
2012年 | 686篇 |
2011年 | 771篇 |
2010年 | 208篇 |
2009年 | 108篇 |
2008年 | 817篇 |
2007年 | 808篇 |
2006年 | 844篇 |
2005年 | 909篇 |
2004年 | 771篇 |
2003年 | 694篇 |
2002年 | 572篇 |
2001年 | 418篇 |
2000年 | 609篇 |
1999年 | 188篇 |
1998年 | 52篇 |
1997年 | 32篇 |
1996年 | 36篇 |
1995年 | 25篇 |
1994年 | 42篇 |
1993年 | 37篇 |
1992年 | 40篇 |
1991年 | 51篇 |
1990年 | 49篇 |
1989年 | 65篇 |
1988年 | 53篇 |
1987年 | 50篇 |
1986年 | 61篇 |
1985年 | 60篇 |
1984年 | 65篇 |
1983年 | 46篇 |
1982年 | 71篇 |
1981年 | 53篇 |
1980年 | 38篇 |
1979年 | 42篇 |
1972年 | 12篇 |
1971年 | 31篇 |
1970年 | 62篇 |
1966年 | 13篇 |
1959年 | 176篇 |
1958年 | 314篇 |
1957年 | 220篇 |
1956年 | 204篇 |
1955年 | 179篇 |
1954年 | 234篇 |
1948年 | 60篇 |
排序方式: 共有10000条查询结果,搜索用时 187 毫秒
291.
Short-term migration, that is stays of less than 12 months, has received particular attention recently from both national and local level users of population statistics. This interest is part of the wider interest shown in increasing levels of long-term migration statistics in recent years. This article is an initial assessment by ONS of the potential to produce short-term migration estimates for England and Wales, and the challenges faced in doing so. Central to these challenges is the question of how short-term migration should be defined. In addition, illustrative estimates of short-term migration based on the International Passenger Survey (IPS) are provided. These illustrative estimates, along with associated standard errors, are provided at both national and regional levels using a number of definitional bases. 相似文献
292.
It is important that migration is measured accurately, for example to inform population estimates and projections. However, current sources of information present challenges in producing robust estimates of emigration from Great Britain. This article reports on work carried out by the Office for National Statistics to investigate the potential for using administrative data sources to contribute to the measurement of emigration. 相似文献
293.
Komen JC Distelmaier F Koopman WJ Wanders RJ Smeitink J Willems PH 《Cellular and molecular life sciences : CMLS》2007,64(24):3271-3281
Refsum disease is a rare, inherited neurodegenerative disorder characterized by accumulation of the dietary branched-chain
fatty acid phytanic acid in plasma and tissues caused by a defect in the alphaoxidation pathway. The accumulation of phytanic
acid is believed to be the main pathophysiological cause of the disease. However, the exact mechanism(s) by which phytanic
acid exerts its toxicity have not been resolved. In this study, the effect of phytanic acid on mitochondrial respiration was
investigated. The results show that in digitonin-permeabilized fibroblasts, phytanic acid decreases ATP synthesis, whereas
substrate oxidation per se is not affected. Importantly, studies in intact fibroblasts revealed that phytanic acid decreases both the mitochondrial
membrane potential and NAD(P)H autofluorescence. Taken together, the results described here show that unesterified phytanic
acid exerts its toxic effect mainly through its protonophoric action, at least in human skin fibroblasts.
Received 4 August 2007; received after revision 26 September 2007; accepted 10 October 2007
J. C. Komen, F. Distelmaier: These authors contributed equally to this work. 相似文献
294.
295.
296.
297.
RNA polymerase is poised for activation across the genome 总被引:2,自引:0,他引:2
Muse GW Gilchrist DA Nechaev S Shah R Parker JS Grissom SF Zeitlinger J Adelman K 《Nature genetics》2007,39(12):1507-1511
298.
299.
Houlden H Johnson J Gardner-Thorpe C Lashley T Hernandez D Worth P Singleton AB Hilton DA Holton J Revesz T Davis MB Giunti P Giunti P Wood NW 《Nature genetics》2007,39(12):1434-1436
The microtubule-associated protein tau (encoded by MAPT) and several tau kinases have been implicated in neurodegeneration, but only MAPT has a proven role in disease. We identified mutations in the gene encoding tau tubulin kinase 2 (TTBK2) as the cause of spinocerebellar ataxia type 11. Affected brain tissue showed substantial cerebellar degeneration and tau deposition. These data suggest that TTBK2 is important in the tau cascade and in spinocerebellar degeneration. 相似文献
300.