全文获取类型
收费全文 | 87篇 |
免费 | 0篇 |
国内免费 | 5篇 |
专业分类
理论与方法论 | 4篇 |
现状及发展 | 15篇 |
研究方法 | 8篇 |
综合类 | 64篇 |
自然研究 | 1篇 |
出版年
2019年 | 2篇 |
2018年 | 2篇 |
2017年 | 2篇 |
2015年 | 1篇 |
2014年 | 1篇 |
2012年 | 4篇 |
2011年 | 5篇 |
2010年 | 4篇 |
2009年 | 2篇 |
2008年 | 4篇 |
2007年 | 6篇 |
2006年 | 6篇 |
2005年 | 3篇 |
2004年 | 3篇 |
2003年 | 1篇 |
2002年 | 2篇 |
2000年 | 32篇 |
1999年 | 1篇 |
1997年 | 3篇 |
1976年 | 1篇 |
1974年 | 2篇 |
1972年 | 1篇 |
1971年 | 1篇 |
1970年 | 2篇 |
1969年 | 1篇 |
排序方式: 共有92条查询结果,搜索用时 609 毫秒
81.
Roman Frigg 《Studies in history and philosophy of science》2003,34(3):613-632
The last decade and a half has seen an ardent development of self-organised criticality (SOC), a new approach to complex systems, which has become important in many domains of natural as well as social science, such as geology, biology, astronomy, and economics, to mention just a few. This has led many to adopt a generalist stance towards SOC, which is now repeatedly claimed to be a universal theory of complex behaviour. The aim of this paper is twofold. First, I provide a brief and non-technical introduction to SOC. Second, I critically discuss the various bold claims that have been made in connection with it. Throughout, I will adopt a rather sober attitude and argue that some people have been too readily carried away by fancy contentions. My overall conclusion will be that none of these bold claims can be maintained. Nevertheless, stripped of exaggerated expectations and daring assertions, many SOC models are interesting vehicles for promising scientific research. 相似文献
82.
83.
Schaffitzel C Oswald M Berger I Ishikawa T Abrahams JP Koerten HK Koning RI Ban N 《Nature》2006,444(7118):503-506
The prokaryotic signal recognition particle (SRP) targets membrane proteins into the inner membrane. It binds translating ribosomes and screens the emerging nascent chain for a hydrophobic signal sequence, such as the transmembrane helix of inner membrane proteins. If such a sequence emerges, the SRP binds tightly, allowing the SRP receptor to lock on. This assembly delivers the ribosome-nascent chain complex to the protein translocation machinery in the membrane. Using cryo-electron microscopy and single-particle reconstruction, we obtained a 16 A structure of the Escherichia coli SRP in complex with a translating E. coli ribosome containing a nascent chain with a transmembrane helix anchor. We also obtained structural information on the SRP bound to an empty E. coli ribosome. The latter might share characteristics with a scanning SRP complex, whereas the former represents the next step: the targeting complex ready for receptor binding. High-resolution structures of the bacterial ribosome and of the bacterial SRP components are available, and their fitting explains our electron microscopic density. The structures reveal the regions that are involved in complex formation, provide insight into the conformation of the SRP on the ribosome and indicate the conformational changes that accompany high-affinity SRP binding to ribosome nascent chain complexes upon recognition of the signal sequence. 相似文献
85.
在信息经济发展中,越来越需要复合性信息技术人才,根据目前信息产业发展进程中对人才方面的基本需要,提出走“产学研”相结合道路培养具有创新意识的信息技术人才的基本思路。 相似文献
86.
船舶锅炉水位模糊控制仿真 总被引:1,自引:1,他引:0
采用一种改进的模糊控制方法,实现锅炉水位控制。仿真实验表明,该控制系统的动态和稳态精度高,过渡过程时间短,对系统参数和结构不确定性具有很好的鲁棒性,采用输入无“零”挡的方案,有助于解决船舶在海上航行的“结构”不稳定问题。 相似文献
87.
在大量动静三轴试验的基础上,研究了水泥改良土试样的应力-应变关系,掺和比及围压等影响因素,以及临界动应力、累计塑性应变、弹性应变及回弹模量的变化规律,同时,还研究了水泥土的回弹模量和动弹性应变与振动次数的变化规律.试验结果表明:水泥土的应力-应变曲线呈软化型,存在明显的应力峰值点;动应力存在一个临界值,土体的变形分为衰减型、破坏型及临界型;水泥土的临界动应力是素土的两倍以上,随掺和比的增加而增长,但增长趋势变缓. 相似文献
88.
89.
90.
An inhomogeneous superconducting state, not yet conclusively identified, was predicted by Fulde and Ferrell and Larkin and Ovchinnikov (FFLO) to arise in superconductors with strong Pauli limiting, a consequence of the electrons' Zeeman (spin) energy in a magnetic field. Radovan et al. propose that the observed cascades of steps in magnetization of the heavy fermion superconductor CeCoIn5, within the recently discovered second low-temperature state, are due to transitions between Landau-level (LL) states with different m-quanta vortices, expected under certain conditions when the magnetic field is swept within the FFLO state. The authors then conclude that the observed steps in magnetization constitute a proof that the low-temperature state in CeCoIn5 is indeed an FFLO state. We argue that this interpretation of the observed steps in magnetization cannot be supported on either quantitative or qualitative grounds. 相似文献