全文获取类型
收费全文 | 944篇 |
免费 | 3篇 |
国内免费 | 4篇 |
专业分类
化学 | 682篇 |
晶体学 | 6篇 |
力学 | 16篇 |
综合类 | 8篇 |
数学 | 73篇 |
物理学 | 166篇 |
出版年
2023年 | 3篇 |
2022年 | 14篇 |
2021年 | 6篇 |
2020年 | 9篇 |
2019年 | 184篇 |
2018年 | 36篇 |
2017年 | 16篇 |
2016年 | 5篇 |
2015年 | 3篇 |
2014年 | 4篇 |
2013年 | 4篇 |
2012年 | 7篇 |
2011年 | 4篇 |
2010年 | 4篇 |
2009年 | 7篇 |
2008年 | 11篇 |
2007年 | 15篇 |
2006年 | 10篇 |
2005年 | 4篇 |
2004年 | 6篇 |
2003年 | 3篇 |
2002年 | 3篇 |
2001年 | 2篇 |
2000年 | 5篇 |
1999年 | 3篇 |
1998年 | 3篇 |
1997年 | 1篇 |
1996年 | 2篇 |
1995年 | 3篇 |
1994年 | 2篇 |
1986年 | 3篇 |
1985年 | 39篇 |
1984年 | 31篇 |
1983年 | 26篇 |
1982年 | 28篇 |
1981年 | 86篇 |
1980年 | 81篇 |
1979年 | 28篇 |
1978年 | 43篇 |
1977年 | 49篇 |
1976年 | 38篇 |
1975年 | 40篇 |
1974年 | 33篇 |
1973年 | 31篇 |
1968年 | 6篇 |
1962年 | 3篇 |
1958年 | 3篇 |
1957年 | 3篇 |
1955年 | 1篇 |
排序方式: 共有951条查询结果,搜索用时 0 毫秒
91.
I discuss the early work of Enrico Fermi (1901-1954) as a student in Pisa at the Scuola Normale
Superiore and at the University of Pisa (1918-1922), paying particular attention to the four papers
he published during those years and to his licenza and doctoral theses. 相似文献
92.
Roland Wittje 《Physics in Perspective (PIP)》2007,9(4):406-433
In the late 1940s and the 1950s, Norwegian nuclear scientists, engineers, and administrators were deeply split over their
nation’s goals, organization, politics, and tools for research in nuclear physics. One faction was determined to build a nuclear
reactor in Norway, while another fiercely opposed the reactor plans and focused on particle accelerators. The first faction
comprised scientific entrepreneurs and research technologists, the second academic scientists, most of whom began their research
careers in nuclear physics in the 1930s. To understand this conflict, I trace the development of nuclear research in Norway
from the early 1930s to the mid-1950s, placing it within an international context.
Roland Wittje is working on his habilitation thesis in the History of Science Unit at the University of Regensburg, Germany. 相似文献
93.
A block considered as a set of elements together with its adjacency matrix A is called a C-block if A is the adjacency matrix of a circuit. A balanced circuit design with parameters v, b, r, k, λ (briefly, BCD(v, k, λ)) is an arrangement of v elements into bC-blocks such that each C-block contains k elements, each element occurs in exactly rC-blocks and any two distinct elements are linked in exactly λ C-blocks.We investigate conditions for the existence of BCD and show, in particular, that if the block-size k ? 6 and the trivial necessary conditions are satisfied, then the corresponding BCD exists. 相似文献
94.
95.
A DMAP (4-dimethylaminopyridine) catalyzed cyclization of methyl 2-alkynylbenzimidates has been developed, which affords 3-methoxy-1-methyleneisoindoles with excellent Z-stereoselectivity under mild and transition-metal-free conditions. The (Z)-3-methoxy-1-methyleneisoindole products can be converted to corresponding 3-amino-1-methyleneisoindoles, 3-methoxy-isoindoles, 3-methyleneisoindolinones and isoindolinones with high efficiency. 相似文献
96.
Berberine chloride (1) upon treatment with NaOAc-Ac2O yields naphthalene derivatives 4 and 5 In like fashion, 8 gives naphthalene 10; isoquinoline methiodide leads to β-naphthyl acetate; and 12 provides 14. The reaction has been extended to the 3-carbonyl pyridinium series where 3-acetylpyridine methiodide and 3-pyridinecarboxaldehyde methiodide furnish lactones 16 and 17, respectively. All these transformations proceed by initial nucleophilic attack of the acetic anhydride anion on the immonium carbon atom. 相似文献
97.
论述了教学研究的重要性和复杂性。提出撰写教学研究论文应符合先进性、创新性、实证性、示范性和发展性等原则。介绍了教学研究涉及的主要领域,研究的主要内容和方法,对如何开展各领域教学研究并撰写高水平的教学研究论文进行了讨论并给出了示例。 相似文献
98.
99.
100.
Dieter Hoffmann 《Physics in Perspective (PIP)》2000,2(4):426-445
A guided tour of significant sides pertaining to the history of physics is conducted around the area of the Technische Universit?t
and the Physikalisch-Technische Reichsanstalt in Berlin-Charlottenburg, of the Institutes of the former Kaiser Wilhelm Society
in Berlin-Dahlem, as well as to some points of interest in the area of Potsdam. 相似文献