全文获取类型
收费全文 | 1088篇 |
免费 | 43篇 |
国内免费 | 36篇 |
专业分类
系统科学 | 20篇 |
丛书文集 | 2篇 |
教育与普及 | 3篇 |
理论与方法论 | 12篇 |
现状及发展 | 337篇 |
研究方法 | 134篇 |
综合类 | 631篇 |
自然研究 | 28篇 |
出版年
2021年 | 4篇 |
2020年 | 5篇 |
2019年 | 15篇 |
2018年 | 21篇 |
2017年 | 18篇 |
2016年 | 19篇 |
2015年 | 19篇 |
2014年 | 27篇 |
2013年 | 31篇 |
2012年 | 76篇 |
2011年 | 101篇 |
2010年 | 40篇 |
2009年 | 33篇 |
2008年 | 61篇 |
2007年 | 70篇 |
2006年 | 60篇 |
2005年 | 75篇 |
2004年 | 43篇 |
2003年 | 66篇 |
2002年 | 60篇 |
2001年 | 43篇 |
2000年 | 43篇 |
1999年 | 23篇 |
1996年 | 4篇 |
1992年 | 10篇 |
1991年 | 7篇 |
1990年 | 4篇 |
1989年 | 10篇 |
1988年 | 9篇 |
1987年 | 9篇 |
1986年 | 5篇 |
1985年 | 9篇 |
1982年 | 6篇 |
1981年 | 7篇 |
1980年 | 8篇 |
1979年 | 8篇 |
1978年 | 7篇 |
1977年 | 10篇 |
1976年 | 5篇 |
1975年 | 9篇 |
1974年 | 5篇 |
1973年 | 9篇 |
1972年 | 3篇 |
1971年 | 9篇 |
1970年 | 9篇 |
1969年 | 7篇 |
1968年 | 5篇 |
1967年 | 7篇 |
1966年 | 5篇 |
1965年 | 7篇 |
排序方式: 共有1167条查询结果,搜索用时 562 毫秒
281.
Shiu‐Sheng Chen 《Journal of forecasting》2005,24(6):453-464
This paper studies in‐sample and out‐of‐sample tests for Granger causality using Monte Carlo simulation. The results show that the out‐of‐sample tests may be more powerful than the in‐sample tests when discrete structural breaks appear in time series data. Further, an empirical example investigating Taiwan's investment–saving relationship shows that Taiwan's domestic savings may be helpful in predicting domestic investments. It further illustrates that a possible Granger causal relationship is detected by out‐of‐sample tests while the in‐sample test fails to reject the null of non‐causality. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
282.
A systematic RNAi screen identifies a critical role for mitochondria in C. elegans longevity 总被引:19,自引:0,他引:19
We report a systematic RNA interference (RNAi) screen of 5,690 Caenorhabditis elegans genes for gene inactivations that increase lifespan. We found that genes important for mitochondrial function stand out as a principal group of genes affecting C. elegans lifespan. A classical genetic screen identified a mutation in the mitochondrial leucyl-tRNA synthetase gene (lrs-2) that impaired mitochondrial function and was associated with longer-lifespan. The long-lived worms with impaired mitochondria had lower ATP content and oxygen consumption, but differential responses to free-radical and other stresses. These data suggest that the longer lifespan of C. elegans with compromised mitochrondria cannot simply be assigned to lower free radical production and suggest a more complex coupling of metabolism and longevity. 相似文献
283.
Reboul J Vaglio P Rual JF Lamesch P Martinez M Armstrong CM Li S Jacotot L Bertin N Janky R Moore T Hudson JR Hartley JL Brasch MA Vandenhaute J Boulton S Endress GA Jenna S Chevet E Papasotiropoulos V Tolias PP Ptacek J Snyder M Huang R Chance MR Lee H Doucette-Stamm L Hill DE Vidal M 《Nature genetics》2003,34(1):35-41
To verify the genome annotation and to create a resource to functionally characterize the proteome, we attempted to Gateway-clone all predicted protein-encoding open reading frames (ORFs), or the 'ORFeome,' of Caenorhabditis elegans. We successfully cloned approximately 12,000 ORFs (ORFeome 1.1), of which roughly 4,000 correspond to genes that are untouched by any cDNA or expressed-sequence tag (EST). More than 50% of predicted genes needed corrections in their intron-exon structures. Notably, approximately 11,000 C. elegans proteins can now be expressed under many conditions and characterized using various high-throughput strategies, including large-scale interactome mapping. We suggest that similar ORFeome projects will be valuable for other organisms, including humans. 相似文献
284.
Recent advances in androgen receptor action 总被引:17,自引:0,他引:17
285.
Maneuf YP Gonzalez MI Sutton KS Chung FZ Pinnock RD Lee K 《Cellular and molecular life sciences : CMLS》2003,60(4):742-750
Gabapentin was originally designed as an anti-convulsant gamma-aminobutyric acid (GABA) mimetic capable of crossing the blood-brain barrier. In the present review we show that although gabapentin is not a GABA mimetic, it has great utility as an add-on therapy for epilepsy and as a first-line treatment for neuropathic pain. We summarise the studies that have been performed which demonstrate that gabapentin appears to interact with a novel binding site expressed at high density within the central nervous system (CNS), namely the alpha2delta voltage-dependent calcium channel subunit. The review continues by examining the effects of gabapentin on calcium channel function and neurotransmitter release before, in the latter part of the review, summarising the more recently discovered actions of gabapentin in relation to intracellular signalling. 相似文献
286.
287.
288.
Defects in whirlin,a PDZ domain molecule involved in stereocilia elongation,cause deafness in the whirler mouse and families with DFNB31 总被引:22,自引:0,他引:22
Mburu P Mustapha M Varela A Weil D El-Amraoui A Holme RH Rump A Hardisty RE Blanchard S Coimbra RS Perfettini I Parkinson N Mallon AM Glenister P Rogers MJ Paige AJ Moir L Clay J Rosenthal A Liu XZ Blanco G Steel KP Petit C Brown SD 《Nature genetics》2003,34(4):421-428
The whirler mouse mutant (wi) does not respond to sound stimuli, and detailed ultrastructural analysis of sensory hair cells in the organ of Corti of the inner ear indicates that the whirler gene encodes a protein involved in the elongation and maintenance of stereocilia in both inner hair cells (IHCs) and outer hair cells (OHCs). BAC-mediated transgene correction of the mouse phenotype and mutation analysis identified the causative gene as encoding a novel PDZ protein called whirlin. The gene encoding whirlin also underlies the human autosomal recessive deafness locus DFNB31. In the mouse cochlea, whirlin is expressed in the sensory IHC and OHC stereocilia. Our findings suggest that this novel PDZ domain-containing molecule acts as an organizer of submembranous molecular complexes that control the coordinated actin polymerization and membrane growth of stereocilia. 相似文献
289.
Parkhill J Sebaihia M Preston A Murphy LD Thomson N Harris DE Holden MT Churcher CM Bentley SD Mungall KL Cerdeño-Tárraga AM Temple L James K Harris B Quail MA Achtman M Atkin R Baker S Basham D Bason N Cherevach I Chillingworth T Collins M Cronin A Davis P Doggett J Feltwell T Goble A Hamlin N Hauser H Holroyd S Jagels K Leather S Moule S Norberczak H O'Neil S Ormond D Price C Rabbinowitsch E Rutter S Sanders M Saunders D Seeger K Sharp S Simmonds M Skelton J Squares R Squares S Stevens K 《Nature genetics》2003,35(1):32-40
Bordetella pertussis, Bordetella parapertussis and Bordetella bronchiseptica are closely related Gram-negative beta-proteobacteria that colonize the respiratory tracts of mammals. B. pertussis is a strict human pathogen of recent evolutionary origin and is the primary etiologic agent of whooping cough. B. parapertussis can also cause whooping cough, and B. bronchiseptica causes chronic respiratory infections in a wide range of animals. We sequenced the genomes of B. bronchiseptica RB50 (5,338,400 bp; 5,007 predicted genes), B. parapertussis 12822 (4,773,551 bp; 4,404 genes) and B. pertussis Tohama I (4,086,186 bp; 3,816 genes). Our analysis indicates that B. parapertussis and B. pertussis are independent derivatives of B. bronchiseptica-like ancestors. During the evolution of these two host-restricted species there was large-scale gene loss and inactivation; host adaptation seems to be a consequence of loss, not gain, of function, and differences in virulence may be related to loss of regulatory or control functions. 相似文献
290.