全文获取类型
收费全文 | 904篇 |
免费 | 50篇 |
国内免费 | 5篇 |
专业分类
化学 | 706篇 |
晶体学 | 5篇 |
力学 | 14篇 |
数学 | 82篇 |
物理学 | 152篇 |
出版年
2023年 | 6篇 |
2022年 | 12篇 |
2021年 | 22篇 |
2020年 | 24篇 |
2019年 | 27篇 |
2018年 | 17篇 |
2017年 | 11篇 |
2016年 | 30篇 |
2015年 | 26篇 |
2014年 | 24篇 |
2013年 | 45篇 |
2012年 | 52篇 |
2011年 | 73篇 |
2010年 | 39篇 |
2009年 | 28篇 |
2008年 | 58篇 |
2007年 | 45篇 |
2006年 | 56篇 |
2005年 | 55篇 |
2004年 | 56篇 |
2003年 | 58篇 |
2002年 | 42篇 |
2001年 | 9篇 |
2000年 | 9篇 |
1999年 | 5篇 |
1998年 | 8篇 |
1997年 | 7篇 |
1996年 | 7篇 |
1994年 | 5篇 |
1993年 | 2篇 |
1992年 | 3篇 |
1991年 | 4篇 |
1990年 | 7篇 |
1989年 | 3篇 |
1988年 | 7篇 |
1987年 | 4篇 |
1986年 | 3篇 |
1985年 | 6篇 |
1984年 | 12篇 |
1982年 | 9篇 |
1981年 | 5篇 |
1980年 | 2篇 |
1979年 | 7篇 |
1976年 | 3篇 |
1974年 | 2篇 |
1973年 | 5篇 |
1971年 | 3篇 |
1970年 | 4篇 |
1969年 | 3篇 |
1968年 | 3篇 |
排序方式: 共有959条查询结果,搜索用时 31 毫秒
101.
Dr. Hiroshi Haruki 《Mathematische Zeitschrift》1968,104(5):358-363
102.
103.
Masayasu Tasaka Satoshi Tamura Naoto Takemura Keisuke Morimoto 《Journal of membrane science》1982,12(2):169-182
Electroosmosis and streaming potential measurements were carried out across charged membranes made of collodion and sulfonated polystyrene. Experiments were confined to the range where linear flux/force relationships hold. Saxén's relationship holds between electroosmosis and streaming potential; for porous charged membranes these exhibit an approximate inverse proportionality to ionic mobility at the limit of low electrolyte concentration. Both tend towards zero at the limit of high electrolyte concentration. 相似文献
104.
105.
The addition of arylboronic acids 1 to azodicarboxylates 2 in the presence of a catalytic amount of a copper salt under mild reaction conditions gives aryl-substituted hydrazines 3 in high yields. The reaction is tolerant of a wide variety of functional groups. 相似文献
106.
The B1A1 state of SiH2 and SiD2 was observed by the optical-optical double resonance technique for the first time. The electronic band origin of the B state of SiD2 was determined to be 27 214.11 cm(-1). A very clear exclusive behavior depending on the even/odd value of the bending vibrational quantum number was observed in the spectra, representing a quasilinear behavior of the B state. The barrier height to linearity was estimated to be approximately 125 cm(-1) by the quasilinear analysis of the bending vibrational level structure of SiD2. 相似文献
107.
The first measurements of magnetization hysteresis loops on a diluted single crystal of [(Pc)2Ho]-.TBA+ (Pc = phthalocyaninato, TBA = tetrabutylammonium) in the subkelvin temperature range are reported. Characteristic staircase-like structure was observed, indicating the occurrence of the quantum tunneling of magnetization (QTM), which is a characteristic feature of SMMs. The quantum process in the new lanthanide SMMs is due to resonant quantum tunneling between entangled states of the electronic and nuclear spin systems, which is an essentially different mechanism from those of the known transition-metal-cluster SMMs. Evidence of the two-body quantum process was also observed for the first time in lanthanide complex systems. 相似文献
108.
Oshita M Yamashita K Tobisu M Chatani N 《Journal of the American Chemical Society》2005,127(2):761-766
The GaCl(3)-catalyzed [4+1] cycloaddition reactions of alpha,beta-unsaturated ketones with isocyanides leading to lactone derivatives are described. While some other Lewis acids also show catalytic activity, GaCl(3) was the most efficient catalyst. The reaction is significantly affected by the structure of both the isocyanides and the alpha,beta-unsaturated ketones. Aromatic isocyanides, especially sterically demanding ones and those bearing an electron-withdrawing group, can be used, but aliphatic isocyanides cannot. The bulkiness of substituents at the beta-position of acyclic alpha,beta-unsaturated ketones is an important factor for the reaction to proceed efficiently. Generally, the more the bulky substituent, the higher is the yield. The reaction of alpha,beta-unsaturated ketones bearing geminal substituents at the beta-position gave the corresponding products in high yields. In monosubstituted derivatives, the yields are relatively low. However, substrates having a bulky substituent, such as a tert-Bu group, at the beta-position give high yields. Bulkiness is also required in cyclic alpha,beta-unsaturated ketones, but the effect is small. In alkyl vinyl ketones, the reactivity decreased with the steric bulk of the alkyl group. In aryl vinyl ketones, the presence of an electron-donating group on the aromatic ring decreases the reactivity. The success of the catalysis can be attributed to the low affinity of GaCl(3) toward heteroatoms, compared with usual Lewis acids. 相似文献
109.
110.