全文获取类型
收费全文 | 3436篇 |
免费 | 195篇 |
国内免费 | 63篇 |
专业分类
系统科学 | 205篇 |
丛书文集 | 149篇 |
教育与普及 | 16篇 |
理论与方法论 | 27篇 |
现状及发展 | 140篇 |
综合类 | 3157篇 |
出版年
2024年 | 1篇 |
2022年 | 10篇 |
2021年 | 18篇 |
2020年 | 14篇 |
2019年 | 9篇 |
2018年 | 17篇 |
2017年 | 17篇 |
2016年 | 15篇 |
2015年 | 31篇 |
2014年 | 726篇 |
2013年 | 498篇 |
2012年 | 389篇 |
2011年 | 419篇 |
2010年 | 435篇 |
2009年 | 441篇 |
2008年 | 397篇 |
2007年 | 37篇 |
2006年 | 15篇 |
2005年 | 23篇 |
2004年 | 16篇 |
2003年 | 11篇 |
2002年 | 16篇 |
2001年 | 19篇 |
2000年 | 10篇 |
1999年 | 5篇 |
1998年 | 10篇 |
1997年 | 11篇 |
1996年 | 13篇 |
1995年 | 10篇 |
1994年 | 8篇 |
1993年 | 4篇 |
1992年 | 4篇 |
1991年 | 11篇 |
1990年 | 7篇 |
1989年 | 9篇 |
1988年 | 8篇 |
1987年 | 6篇 |
1985年 | 4篇 |
排序方式: 共有3694条查询结果,搜索用时 15 毫秒
1.
‘Holographic’ relations between theories have become an important theme in quantum gravity research. These relations entail that a theory without gravity is equivalent to a gravitational theory with an extra spatial dimension. The idea of holography was first proposed in 1993 by Gerard ׳t Hooft on the basis of his studies of evaporating black holes. Soon afterwards the holographic ‘AdS/CFT’ duality was introduced, which since has been intensively studied in the string theory community and beyond. Recently, Erik Verlinde has proposed that even Newton׳s law of gravitation can be related holographically to the ‘thermodynamics of information’ on screens. We discuss these scenarios, with special attention to the status of the holographic relation in them and to the question of whether they make gravity and spacetime emergent. We conclude that only Verlinde׳s scheme straightforwardly instantiates emergence. However, assuming a non-standard interpretation of AdS/CFT may create room for the emergence of spacetime and gravity there as well. 相似文献
2.
Meir Hemmo Orly Shenker 《Studies in History and Philosophy of Science Part B: Studies in History and Philosophy of Modern Physics》2005,36(4):389
In a previous paper [Hemmo, M & Shenker, O (2003). Quantum decoherence and the approach to equilibrium I. Philosophy of Science, 70, 330–358] we discussed a recent proposal by Albert [(2000). Time and chance. Cambridge, MA: Harvard University Press. Chapter 7] to recover thermodynamics on a purely dynamical basis, using the quantum theory of the collapse of the quantum state of [Ghirardi, G, Rimini, A and Weber, T., (1986). Unified dynamics for microscopic and macroscopic systems. Physical Review, D 34, 470–479]. We proposed an alternative way to explain thermodynamics within no collapse interpretations of quantum mechanics. In this paper some difficulties faced by both approaches are discussed and solved: the spin echo experiments, and the problem of extremely light gases. In these contexts, we point out several ways in which the above quantum mechanical approaches as well as some other classical approaches to the foundations of statistical mechanics may be distinguished experimentally. 相似文献
3.
Science Letters: A synthetic Toll-like receptor 2 ligand decreases allergic immune responses in a mouse rhinitis model sensitized to mite allergen 下载免费PDF全文
It has been proposed that activation of Toll-like receptors (TLRs) plays crucial roles in the polarization of adaptive immune responses. A synthetic Toll-like receptor 2 (TLR2) ligand, Pam3CSK4, has been reported to modulate the balance of Th1/Th2 responses. We evaluated the modulation effect of Pam3CSK4 on allergic immune response in a mouse rhinitis model sensitized to house dust mite allergen (HDM). Mice were sensitized and challenged with Dermatophagoidesfarinae allergen (Der f), and then the allergic mice were treated by Pam3CSK4. Nasal allergic symptoms and eosinophils were scored. Der f-specific cytokine responses were examined in the splenocytes and bronchoalveolar lavage fluid (BALF). Serum level of total IgE was also detected. After establishing a mouse allergic rhinitis model with HDM, we have showed that Pam3CSK4 treatment not only ameliorated the nasal allergic symptoms remarkably but also decreased the eosinophils and total inflammation cells in BALF significantly. Analysis of cytokine profile found that IFN-7 released from either BALF or stimulated splenocytes increased markedly in Pam3CSK4-treated mice, while IL-13 decreased significantly. Moreover, serum level of total IgE was significantly lower in Pam3CSK4-treated mice than in the untreated. Thus, in an allergic rhinitis mouse model developed with HDM, Pam3CSK4 was shown to exhibit an antiallergic effect, indicating its potential application in allergic diseases. 相似文献
4.
5.
6.
蔡香民 《阜阳师范学院学报(自然科学版)》2002,19(1):62-65
本文较系统地介绍了有关原子结构方面的一些基础理论,由定性到定量,并应用量子力学知识描绘了原子结构状态。 相似文献
7.
从量子力学、真空、大数假说、磁单极子诸方面,阐述了坎拉克的治学思想和研究方法的特点及其对当代物理学所做出的重大贡献. 相似文献
8.
从日本人的“ラち”、“そと”意识角度出发,通过对川端康成、志贺直哉的几部小说进行分析统计,探讨日语在描写过去的事件中,插入“内时态‘る’形”的条件和原因。分析发现当作者为了使作品更生动,或是作者与作品中人物产生“同感”时,或是表达作者的主观思想、评论时,往往发生时态的转换。 相似文献
9.
利用量子么正变换引起拓扑项的可移性,求出了一维无限深运动边界方势阱在压缩变换中出现的微扰项在一级近似下对Berry相因子的贡献。 相似文献
10.
R.E. Kastner 《Studies in History and Philosophy of Science Part B: Studies in History and Philosophy of Modern Physics》2005,36(4):649-658
A modified version of Young's experiment by Shahriar Afshar demonstrates that, prior to what appears to be a “which-way” measurement, an interference pattern exists. Afshar has claimed that this result constitutes a violation of the Principle of Complementarity. This paper discusses the implications of this experiment and considers how Cramer's Transactional Interpretation easily accommodates the result. It is also shown that the Afshar experiment is analogous in key respects to a spin one-half particle prepared as “spin up along x”, subjected to a nondestructive confirmation of that preparation, and post-selected in a specific state of spin along z. The terminology “which-way” or “which-slit” is critiqued; it is argued that this usage by both Afshar and his critics is misleading and has contributed to confusion surrounding the interpretation of the experiment. Nevertheless, it is concluded that Bohr would have had no more problem accounting for the Afshar result than he would in accounting for the aforementioned pre- and post-selection spin experiment, in which the particle's preparation state is confirmed by a nondestructive measurement prior to post-selection. In addition, some new inferences about the interpretation of delayed choice experiments are drawn from the analysis. 相似文献