全文获取类型
收费全文 | 9997篇 |
免费 | 274篇 |
国内免费 | 45篇 |
专业分类
化学 | 7291篇 |
晶体学 | 124篇 |
力学 | 173篇 |
数学 | 733篇 |
物理学 | 1995篇 |
出版年
2022年 | 78篇 |
2021年 | 79篇 |
2020年 | 116篇 |
2019年 | 140篇 |
2018年 | 88篇 |
2017年 | 69篇 |
2016年 | 158篇 |
2015年 | 167篇 |
2014年 | 205篇 |
2013年 | 505篇 |
2012年 | 508篇 |
2011年 | 572篇 |
2010年 | 315篇 |
2009年 | 328篇 |
2008年 | 580篇 |
2007年 | 615篇 |
2006年 | 621篇 |
2005年 | 522篇 |
2004年 | 437篇 |
2003年 | 417篇 |
2002年 | 409篇 |
2001年 | 183篇 |
2000年 | 187篇 |
1999年 | 144篇 |
1998年 | 94篇 |
1997年 | 126篇 |
1996年 | 147篇 |
1995年 | 91篇 |
1994年 | 96篇 |
1993年 | 98篇 |
1992年 | 114篇 |
1991年 | 93篇 |
1990年 | 77篇 |
1989年 | 73篇 |
1988年 | 98篇 |
1987年 | 86篇 |
1986年 | 88篇 |
1985年 | 146篇 |
1984年 | 150篇 |
1983年 | 69篇 |
1982年 | 126篇 |
1981年 | 115篇 |
1980年 | 113篇 |
1979年 | 115篇 |
1978年 | 103篇 |
1977年 | 97篇 |
1976年 | 85篇 |
1975年 | 72篇 |
1974年 | 74篇 |
1973年 | 88篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
The regional cerebral blood flow (CBF) was determined on seventeen patients with brain tumors. Ring type single photon emission CT (SPECT) was used following intravenous injection of 133Xe. Case materials included eleven meningiomas and six malignant gliomas. Evaluation was performed with emphasis on the following points; Correlation of the flow data within tumors to the angiographic tumor stains, Influence of tumors on the cerebral blood flow of the normal brain tissue, Correlation between degree of peripheral edema and the flow data of the affected hemispheres. There was significant correlation between flow data within tumors and angiographic tumor stains in meningiomas. Influence of tumors on cerebral blood flow of the normal tissue was greater in meningiomas than in gliomas. There was negative correlation between the degree of peripheral edema and the flow data of the affected hemisphere. It has been concluded that the measurement of CBF in brain tumors is a valuable method in evaluation of brain tumors. 相似文献
92.
93.
94.
Enhancement of electronic excitation energy transfer in the colloidal crystals of colloidal silica suspensions doped with fluorescent dyes 总被引:1,自引:0,他引:1
Kiyoshi Shibata Hiroshi Kimura Akira Tsuchida Tsuneo Okubo 《Colloid and polymer science》2006,285(2):127-133
The efficiency of electronic excitation energy transfer from photo-excited rhodamine 110 (Rh110, energy donor) to rhodamine B (RhB, energy acceptor) in an exhaustively deionized colloidal silica suspension has been studied. This colloidal suspension shows Bragg reflection due to the formation of colloidal crystals and the Bragg-peak wavelength is controllable by the volume fraction of the silica spheres. When the Bragg-peak wavelength matches with the fluorescence band of Rh110, a depletion was observed in the Rh110 fluorescence spectrum. This means the fluorescence of Rh110 is partially trapped due to the Bragg reflection inside the crystal lattice. In the coexistence of RhB, the enhancement of RhB fluorescence intensity was observed. These facts clearly indicate the trapped photon energy of Rh110 is efficiently transferred to RhB within the colloidal crystals. The quantitative measurements showed that the enhancement of the transfer efficiency is 20% (or slightly more) in the present experimental conditions. 相似文献
95.
Production of submicron-size monodisperse polymer particles having aldehyde groups by seeded aldol condensation polymerization 总被引:2,自引:0,他引:2
Submicron-size monodisperse polystyrene/polyglutaraldehyde composite particles having aldehyde groups at the surfaces were produced by seeded aldol condensation polymerization of glutaraldehyde in the presence of polystyrene particles prepared by emulsifier-free emulsion polymerization. This technique is expected to be useful for the production of size-controlled polymer particles having aldehyde groups.Part CXXXVI of the series Studies on Suspension and Emulsion 相似文献
96.
Jiann-Kuan Luo Kazufumi Takahashi J. Dew Mckenney Raymond N. Castle Milton L. Lee 《Journal of heterocyclic chemistry》1989,26(6):1845-1848
The synthesis of 2-naphthyl 2′-dibenzothienyl ether, 1-(1′-naphthyl)-2-(4″-acridinyl)ethane and a series of naphthylethyldibenzothiophenes is reported. 相似文献
97.
98.
Kinetics of chemiluminescence reactions of 2-methyl-6-phenylimidazo[1,2-a]pyrazin-3(7H)-one (1c, Cypridina luciferin analogue) and substituent effects of the 6-aryl group of derivatives 1 strongly suggest that the rate-determining step is a single electron transfer from an anion derived from 1 to a triplet molecular oxygen (O2) in the oxygenation process. 相似文献
99.
100.