全文获取类型
收费全文 | 145篇 |
免费 | 1篇 |
专业分类
系统科学 | 3篇 |
理论与方法论 | 1篇 |
现状及发展 | 37篇 |
研究方法 | 29篇 |
综合类 | 65篇 |
自然研究 | 11篇 |
出版年
2022年 | 1篇 |
2019年 | 1篇 |
2018年 | 2篇 |
2017年 | 3篇 |
2016年 | 4篇 |
2015年 | 2篇 |
2013年 | 2篇 |
2012年 | 11篇 |
2011年 | 24篇 |
2010年 | 1篇 |
2008年 | 8篇 |
2007年 | 13篇 |
2006年 | 11篇 |
2005年 | 7篇 |
2004年 | 11篇 |
2003年 | 12篇 |
2002年 | 12篇 |
1999年 | 1篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1982年 | 1篇 |
1981年 | 3篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 2篇 |
1976年 | 3篇 |
1971年 | 1篇 |
1970年 | 2篇 |
1968年 | 2篇 |
1967年 | 1篇 |
排序方式: 共有146条查询结果,搜索用时 15 毫秒
1.
During the long eighteenth century, boundaries between theology and natural philosophy, between imaginary and factual travel narratives, between fiction and social commentary, were far more fluid than they are today. To explore these relationships, this paper links Mary Shelley’s Frankenstein—a book often hailed as the first science fiction novel—to two earlier works which are now less well known: Edmond Halley’s article about terrestrial magnetism, in which he suggested that God had created inhabited illuminated cavities inside the earth; and a satirical fantasy voyage written by the Danish author Ludvig Holberg, but published anonymously as Niels Klim’s journey to the underground and immediately translated into many languages. Attention is focussed on how the ambiguous presentation of these and other texts blurs any straightforward classification of genres. The aim of examining these writers together is not to search for direct mappings from one project to another, but instead to introduce Holberg’s unfamiliar yet important book and also to cast new light on Frankenstein, one of England’s most famous works of literature. 相似文献
2.
Patricia M. Kralik Beng T. Ho H. R. Matthews 《Cellular and molecular life sciences : CMLS》1976,32(6):723-725
Summary
9 (10 mg/kg, i.p.) administered to mice immediately after withdrawal from a 3-day exposure to ethanol vapor was found to intensify withdrawal reactions. No effect was seen when
9 was administered chronically during the exposure to ethanol. 相似文献
3.
Patricia A. Burrowes María Celeste Martes Mónica Torres-Ríos Ana V. Longo 《Journal of Natural History》2017,51(11-12):643-656
Pathogen-mediated changes in host behaviour can result from hosts altering their habitat preferences. Although infection risk with pathogenic fungus Batrachochytrium dendrobatidis in amphibians is associated with environments favouring its growth, the relationship with microhabitat use has not been examined. Here, we aim to determine if microhabitats used by frogs during their nocturnal activity predict B. dendrobatidis prevalence and infection intensity. Our focal host, Eleutherodactylus coqui, is a habitat generalist that uses multiple habitats from the forest floor to the canopy. We analysed data on B. dendrobatidis occurrence in 157 adults and 122 juveniles at El Yunque National forest in Puerto Rico. We categorized each individual’s nocturnal microhabitat as forest floor, curled palm fronds in the floor, arboreal bromeliads and foliage or tree trunks 50 cm to 2.5 m above ground. We found that frogs on the forest floor had the greatest B. dendrobatidis prevalence (73%), compared with those active in vegetation above ground (55%). Overall, the probability of B. dendrobatidis infection in frogs using microhabitats on the forest floor was twice as great as for those on arboreal substrates. Differences in B. dendrobatidis prevalence and intensity in E. coqui may be explained by specific abiotic conditions of microenvironments (temperature and humidity) affecting both pathogen and host, and by the age-specific ecological requirements of hosts. Adults were found to be most active in microhabitats where individuals had lower infection burdens, suggesting pathogen-modulated habitat choice. This work has important implications for the evolutionary dynamics of enzootic diseases and provides data that may inform potential mitigation strategies against a generalist amphibian pathogen. 相似文献
4.
5.
Ultracold atoms trapped by light offer robust quantum coherence and controllability, providing an attractive system for quantum information processing and for the simulation of complex problems in condensed matter physics. Many quantum information processing schemes require the manipulation and deterministic entanglement of individual qubits; this would typically be accomplished using controlled, state-dependent, coherent interactions among qubits. Recent experiments have made progress towards this goal by demonstrating entanglement among an ensemble of atoms confined in an optical lattice. Until now, however, there has been no demonstration of a key operation: controlled entanglement between atoms in isolated pairs. Here we use an optical lattice of double-well potentials to isolate and manipulate arrays of paired (87)Rb atoms, inducing controlled entangling interactions within each pair. Our experiment realizes proposals to use controlled exchange coupling in a system of neutral atoms. Although 87Rb atoms have nearly state-independent interactions, when we force two atoms into the same physical location, the wavefunction exchange symmetry of these identical bosons leads to state-dependent dynamics. We observe repeated interchange of spin between atoms occupying different vibrational levels, with a coherence time of more than ten milliseconds. This observation demonstrates the essential component of a neutral atom quantum SWAP gate (which interchanges the state of two qubits). Its 'half-implementation', the root SWAP gate, is entangling, and together with single-qubit rotations it forms a set of universal gates for quantum computation. 相似文献
6.
International Consortium for Blood Pressure Genome-Wide Association Studies Ehret GB Munroe PB Rice KM Bochud M Johnson AD Chasman DI Smith AV Tobin MD Verwoert GC Hwang SJ Pihur V Vollenweider P O'Reilly PF Amin N Bragg-Gresham JL Teumer A Glazer NL Launer L Zhao JH Aulchenko Y Heath S Sõber S Parsa A Luan J Arora P Dehghan A Zhang F Lucas G Hicks AA Jackson AU Peden JF Tanaka T Wild SH Rudan I Igl W Milaneschi Y Parker AN Fava C Chambers JC Fox ER Kumari M Go MJ van der Harst P Kao WH 《Nature》2011,478(7367):103-109
Blood pressure is a heritable trait influenced by several biological pathways and responsive to environmental stimuli. Over one billion people worldwide have hypertension (≥140?mm?Hg systolic blood pressure or ≥90?mm?Hg diastolic blood pressure). Even small increments in blood pressure are associated with an increased risk of cardiovascular events. This genome-wide association study of systolic and diastolic blood pressure, which used a multi-stage design in 200,000 individuals of European descent, identified sixteen novel loci: six of these loci contain genes previously known or suspected to regulate blood pressure (GUCY1A3-GUCY1B3, NPR3-C5orf23, ADM, FURIN-FES, GOSR2, GNAS-EDN3); the other ten provide new clues to blood pressure physiology. A genetic risk score based on 29 genome-wide significant variants was associated with hypertension, left ventricular wall thickness, stroke and coronary artery disease, but not kidney disease or kidney function. We also observed associations with blood pressure in East Asian, South Asian and African ancestry individuals. Our findings provide new insights into the genetics and biology of blood pressure, and suggest potential novel therapeutic pathways for cardiovascular disease prevention. 相似文献
7.
8.
9.
Diego Reginensi Patricia Carulla Sara Nocentini Oscar Seira Abel Torres-Espín Andreu Matamoros-Angles Rosalina Gavín María Teresa Moreno-Flores Francisco Wandosell Josep Samitier Xavier Trepat Xavier Navarro José Antonio del Río 《Cellular and molecular life sciences : CMLS》2015,72(14):2719-2737
Olfactory ensheathing cell (OEC) transplantation emerged some years ago as a promising therapeutic strategy to repair injured spinal cord. However, inhibitory molecules are present for long periods of time in lesioned spinal cord, inhibiting both OEC migration and axonal regrowth. Two families of these molecules, chondroitin sulphate proteoglycans (CSPG) and myelin-derived inhibitors (MAIs), are able to trigger inhibitory responses in lesioned axons. Mounting evidence suggests that OEC migration is inhibited by myelin. Here we demonstrate that OEC migration is largely inhibited by CSPGs and that inhibition can be overcome by the bacterial enzyme Chondroitinase ABC. In parallel, we have generated a stable OEC cell line overexpressing the Nogo receptor (NgR) ectodomain to reduce MAI-associated inhibition in vitro and in vivo. Results indicate that engineered cells migrate longer distances than unmodified OECs over myelin or oligodendrocyte-myelin glycoprotein (OMgp)-coated substrates. In addition, they also show improved migration in lesioned spinal cord. Our results provide new insights toward the improvement of the mechanisms of action and optimization of OEC-based cell therapy for spinal cord lesion. 相似文献
10.
Purdue MP Johansson M Zelenika D Toro JR Scelo G Moore LE Prokhortchouk E Wu X Kiemeney LA Gaborieau V Jacobs KB Chow WH Zaridze D Matveev V Lubinski J Trubicka J Szeszenia-Dabrowska N Lissowska J Rudnai P Fabianova E Bucur A Bencko V Foretova L Janout V Boffetta P Colt JS Davis FG Schwartz KL Banks RE Selby PJ Harnden P Berg CD Hsing AW Grubb RL Boeing H Vineis P Clavel-Chapelon F Palli D Tumino R Krogh V Panico S Duell EJ Quirós JR Sanchez MJ Navarro C Ardanaz E Dorronsoro M Khaw KT Allen NE 《Nature genetics》2011,43(1):60-65