全文获取类型
收费全文 | 4432篇 |
免费 | 198篇 |
国内免费 | 947篇 |
专业分类
化学 | 2388篇 |
晶体学 | 5篇 |
力学 | 350篇 |
综合类 | 46篇 |
数学 | 924篇 |
物理学 | 1864篇 |
出版年
2021年 | 1篇 |
2020年 | 1篇 |
2016年 | 6篇 |
2015年 | 6篇 |
2014年 | 14篇 |
2013年 | 49篇 |
2012年 | 58篇 |
2011年 | 1079篇 |
2010年 | 533篇 |
2009年 | 556篇 |
2008年 | 82篇 |
2007年 | 86篇 |
2006年 | 123篇 |
2005年 | 195篇 |
2004年 | 907篇 |
2003年 | 555篇 |
2002年 | 398篇 |
2001年 | 187篇 |
2000年 | 99篇 |
1999年 | 85篇 |
1998年 | 78篇 |
1997年 | 53篇 |
1996年 | 35篇 |
1995年 | 32篇 |
1994年 | 34篇 |
1993年 | 104篇 |
1992年 | 72篇 |
1991年 | 35篇 |
1990年 | 42篇 |
1989年 | 43篇 |
1988年 | 25篇 |
1986年 | 2篇 |
1985年 | 1篇 |
1984年 | 1篇 |
排序方式: 共有5577条查询结果,搜索用时 15 毫秒
821.
HOU A-li MENG Qing-fan AN Jin-shuang ZHU Kai FENG Yun TENG Li-rong College of Life Science Jilin University Changchun P. R. China 《高等学校化学研究》2008,24(5):584-587
The crude polysaccharide was obtained by means of the decolorization of porphyrized Cordyceps minlitaris stroma with organic solvent, extraction with hot water, precipitation in 80% ethanol, and protein removal with the Sevag method. After purification with Sephadex G-75, two of its components, CMP-1 and CMP-2, were obtained. Through the assay of gel chromatography and polarimetry, CMP-1 was identified as pure polysaccharide. The results demonstrated that CMP-1 had favorable oxidation resistance activity, which could scavenge not only oxygen-free radicals in the self-oxidation system of pyrogallic acid, but also the hydroxide-free radicals in the Fenton system. The study focused on the effects of low, medium, and high dosages of CMP-1 in rat blood serum on the proliferation of glomerular mesangial cells in vitro. Through MTT Colorimetric analysis, the activities were compared among the blank control group and the Niaoduqing positive control group CMP-1 and CMP-2. The results shows that CMP-1 was able to inhibit the proliferation of rat glomerular mesangial cells effectively. Therefore, CMP-1, one component of polysaccharides of Cordyceps minlitaris, was certainly a potential remedy for hyperplastic glomerular nephritis, whose antioxidant activity could slow down the process of chronic renal failure(CRF) to some extent. 相似文献
822.
Kai An Yao Na Wang Jing Yue Zhuang Zheng Biao Yang Hai Yan Ni Quan Xu Cheng Sun Shu Ping Bi 《中国化学快报》2007,18(7):857-860
In this paper, differential pulse voltammetry (DPV) was applied to study the effects of aluminum Al(Ⅲ) on the lactate dehydrogenase (LDH) activity. Michaelis–Menten constant (KmN ADH) and maximum velocity (vmax) in the enzyme promoting catalytic reaction of "pyruvate(Pyr) NADH H LDDHlactate NAD " under different conditions by monitoring DPV reduction current of NAD were reported. 相似文献
823.
824.
825.
826.
827.
采用FFT方法和增益介质近腔镜簿层处理法研究了非稳腔下具有非均匀流动介质的高功率气体激光器的光束特性和光束质量,证实了该方法在小扰动、低放大率、低增益器件的腔型中是适用的。 相似文献
828.
829.
Supported by the Ministry of Posts Telecommunications the National Natural Science Foundation of China.QI Jiang CHI Nan ZHENG Yuan CHEN Shuqiang GUAN Kejian 《Chinese Journal of Lasers》2000,9(6):488-492
1 Introduction IntheWDMnetwork ,thedesirablefeaturesofanall opticalwavelengthconverterincludepolarizationinsensitivity ,transparencetomodulationformatandbit rate ,fulltunability ,acceptableoutputSNRovertheentirerangeofthewavelengthsusedinthenetwork[1] .Wave… 相似文献
830.