全文获取类型
收费全文 | 1830篇 |
免费 | 71篇 |
国内免费 | 15篇 |
专业分类
化学 | 1401篇 |
晶体学 | 10篇 |
力学 | 43篇 |
综合类 | 1篇 |
数学 | 147篇 |
物理学 | 314篇 |
出版年
2022年 | 22篇 |
2021年 | 20篇 |
2020年 | 31篇 |
2019年 | 26篇 |
2018年 | 30篇 |
2017年 | 25篇 |
2016年 | 56篇 |
2015年 | 50篇 |
2014年 | 48篇 |
2013年 | 83篇 |
2012年 | 119篇 |
2011年 | 90篇 |
2010年 | 73篇 |
2009年 | 59篇 |
2008年 | 122篇 |
2007年 | 113篇 |
2006年 | 116篇 |
2005年 | 124篇 |
2004年 | 93篇 |
2003年 | 75篇 |
2002年 | 70篇 |
2001年 | 29篇 |
2000年 | 24篇 |
1999年 | 27篇 |
1998年 | 22篇 |
1997年 | 11篇 |
1996年 | 20篇 |
1995年 | 18篇 |
1994年 | 6篇 |
1993年 | 10篇 |
1992年 | 8篇 |
1991年 | 12篇 |
1988年 | 13篇 |
1987年 | 8篇 |
1985年 | 21篇 |
1984年 | 20篇 |
1982年 | 22篇 |
1981年 | 15篇 |
1980年 | 16篇 |
1979年 | 28篇 |
1978年 | 14篇 |
1977年 | 18篇 |
1976年 | 16篇 |
1975年 | 14篇 |
1974年 | 8篇 |
1972年 | 7篇 |
1970年 | 9篇 |
1969年 | 9篇 |
1967年 | 7篇 |
1966年 | 6篇 |
排序方式: 共有1916条查询结果,搜索用时 15 毫秒
121.
Hironao SajikiAkira Yamada Kanoko YasunagaTakashi Tsunoda Mumen F.A. AmerKosaku Hirota 《Tetrahedron letters》2003,44(10):2179-2181
A novel chemical modification was achieved at the 5-position of 2′,3′-O-isopropylideneuridine (6) in a one-pot procedure and a remarkable effect of the base on the progress of the reaction was found. 相似文献
122.
In this paper, we establish existence results for positive solutions for the (n−1,1) three-point boundary value problems consisting of the equation
123.
BRST resolution is studied for the principally graded Wakimoto module of
recently found in math.QA/0005203. The submodule structure is completely determined and irreducible representations can be obtained as the zero-th cohomology group. 相似文献
124.
Effects of organic modifiers on the size-controlled synthesis of hydroxyapatite nanorods 总被引:1,自引:0,他引:1
Aili Wang Dong Liu Yuji Wada Yiqing Xu Xiaonong Cheng 《Applied Surface Science》2007,253(6):3311-3316
Size-controlled synthesis of hydroxyapatite nanorods were carried out by chemical precipitation method using polyethylene glycol (MW 600), Tween 20, trisodium citrate, and d-sorbitol as organic modifiers and starting from calcium nitrate, phosphoric acid, and ammonia solution. The influence of the organic modifiers on the sizes of the resultant HAP nanorods was investigated under different synthesis temperatures. It was found that polyethylene glycol was beneficial to the formation of HAP nanorods with a larger aspect ratio (average length/average diameter) at high synthesis temperature, Tween 20 and trisodium citrate favored the formation of small-sized HAP nanorods, and d-sorbitol helped the formation of HAP nanorods with long length at low synthesis temperatures. 相似文献
125.
126.
Low-velocity pneumatic conveying in horizontal pipe for coarse particles and fine powders 总被引:3,自引:0,他引:3
First,the characteristics of low-velocity conveying of particles having different hardness are experimentally investigated in a horizontal pipeline in terms of flow pattern and pressure drop to show that the slug flow can be classified into two types depending on the settling of particles along the pipeline,and the period is small for slug flow without the settled layer,which is called solitary slug flow.The pressure drop for soft particles is shown to be larger than that for hard particles.Then,experimental results are presented on horizontal fluidized-bed conveying of fine powders to show that air release from the top surface of the conveying channel is an important factor for high mass flow rate of particles. 相似文献
127.
128.
129.
130.
Yoichi Tanaka Yuji Taniguchi Daisaku Tanaka Masatoshi Toyoda Hideshi Ishii Teruo Tanabe Yasuko Terada Shinjiro Hayakawa Jun Kawai 《Analytical sciences》2005,21(7):839-843
The Kosa (yellow sand) aerosol affects the global environment as well as human health because it migrates from the interior of China to other areas, absorbing various atmospheric elements. Investigation into individual Kosa aerosol particles, which are submicroscopic to several tens of micrometers in diameter, is required to resolving the issue. We installed a scanning electron microscope (SEM) equipped with an energy dispersive X-ray spectrometer (EDX) on a synchrotron radiation (SR) beam line and introduced the SR beam into the SEM chamber for combinatorial application of SEM-EDX and SR X-ray fluorescence (SR-XRF) spectrometry to individual particles. It should be noted that detailed topographic observation by SEM and sensitive elemental analysis by SR-XRF, both crucial for individual particle measurement but which previously had to be carried out separately, were jointly performed inside the SEM chamber in this setup. Here, we show that SR-XRF results, in conjunction with SEM images, contributed toward resolving individual particle dispositions. Atmospheric sulfur primarily adheres to calcium in the aerosol particles and the particle surface roughens as a consequence of the chemical reaction between the two elements. 相似文献