全文获取类型
收费全文 | 3563篇 |
免费 | 569篇 |
国内免费 | 1960篇 |
专业分类
化学 | 4069篇 |
晶体学 | 192篇 |
力学 | 411篇 |
综合类 | 93篇 |
数学 | 157篇 |
物理学 | 1170篇 |
出版年
2024年 | 29篇 |
2023年 | 89篇 |
2022年 | 131篇 |
2021年 | 158篇 |
2020年 | 142篇 |
2019年 | 133篇 |
2018年 | 93篇 |
2017年 | 132篇 |
2016年 | 146篇 |
2015年 | 164篇 |
2014年 | 239篇 |
2013年 | 278篇 |
2012年 | 249篇 |
2011年 | 224篇 |
2010年 | 239篇 |
2009年 | 247篇 |
2008年 | 325篇 |
2007年 | 331篇 |
2006年 | 294篇 |
2005年 | 285篇 |
2004年 | 334篇 |
2003年 | 302篇 |
2002年 | 252篇 |
2001年 | 194篇 |
2000年 | 115篇 |
1999年 | 123篇 |
1998年 | 112篇 |
1997年 | 103篇 |
1996年 | 101篇 |
1995年 | 95篇 |
1994年 | 62篇 |
1993年 | 71篇 |
1992年 | 80篇 |
1991年 | 78篇 |
1990年 | 53篇 |
1989年 | 56篇 |
1988年 | 15篇 |
1987年 | 10篇 |
1986年 | 4篇 |
1985年 | 3篇 |
1983年 | 1篇 |
排序方式: 共有6092条查询结果,搜索用时 0 毫秒
21.
22.
23.
A simple shooting method dedicated to the design of multipump discrete Raman fibre amplifiers (RFAs) ispro posed and discussed in detail. A novel scheme to provide a good initial guess for backward lightwaves is also proposed to improve the efficiency and robustness of the method. Using the proposed method, a discrete RFA with four backward pumps and 93 signal channels is simulated for the maximum number of interaction waves considered simultaneously in the RFA design reported previously; to our best knowledge. The numerical simulation results show that the proposed method is fast and robust. It can be used in the design of RFAs with various configurations including co-, counter- and bi-directJonal-pump schemes to provide an actual modelling. 相似文献
24.
The self-mixing interference in dual-polarization microchip Nd: YA G lasers is demonstrated. Under optical feedback, the orthogonal polarization components of the laser would undergo antiphase intensity modulations; at high feedback level, the polarization switching appears. We also observe that the laser self-mixing sensitivity changes periodically with the frequency difference of orthogonal polarizations. An initial theoretical model is put out and agrees well with the experiments. The results are useful for self-mixing sensitivity enhancement and offer a new way of absolute distance measurement. 相似文献
25.
26.
High—Efficiency Organic Double—Quantum—Well Light—Emitting Devices Using 5,6,11,12—Tetraphenylnaphthacene Sub—monolayer as Potential Well
下载免费PDF全文
![点击此处可从《中国物理快报》网站下载免费的PDF全文](/ch/ext_images/free.gif)
XIEWen-Fa LIChuan-Nan LIUShi-Yong 《中国物理快报》2003,20(6):956-958
The double-quantum-well organic light-emitting devices of indium-tin-oxide (ITO)/NPB (50nm)/rubrene (0.05nm)/NPB (4nm)/rubrene (0.05nm)/Alq3 (50nm)/LiF (0.5nm)/Al were fabricated, in which N,N-bis-(1-naphthyl)-N,N‘-diphenyl-1,1‘-biphenyl-4,4‘‘‘‘‘‘‘‘-diamine (NPB) is used as a barrier potential or hole transport layer, tris (8-hydroxyquinoline) aluminium (Alq3) used as electron transport layer, and 5,6,11,12-tetraphenylnaphthacene (rubrene) as a potential well and emitter. The brightness can reach 18610cd/m^2 at 13V. The maximum electroluminescent efficiency of the device was 6.61cd/A at 7V, which was higher than that of common dope-type devices. In addition, the electroluminescence efficiency is relatively independent of the drive voltage in the range from 5 to 13V. 相似文献
27.
A Fully Vectorial Effective Index Method for Accurate Dispersion Calculation of Photonic Crystal Fibres
下载免费PDF全文
![点击此处可从《中国物理快报》网站下载免费的PDF全文](/ch/ext_images/free.gif)
A fully vectorial effective index method is developed for accurate dispersion calculation of photonic crystal fibres (PCFs). In order to improve the accuracy of the model, different values for the effective core radius are used when PCFs have different fibre parameters. The accuracy of our approach is demonstrated by comparing our results with other numerical and experimental results reported in literature. It is found that the accuracy of the fully vectorial effective index method is improved and our results agree well with accurate numerical results obtained by other methods as well as the previously reported experimental data. 相似文献
28.
新鲜猪肾匀浆后,经热处理、盐析、羟基磷灰石和DEAE-纤维素柱层析等纯化步骤,二胺氧化酶的收得率为23.9%,纯化倍数为425.该酶进行凝胶电泳后,经氨基黑、酶活性和NBT溶液染色分别得到相对应的蛋白质、酶活性及醌辅基谱带.该酶可与腐胺、尸胺、己二胺、组胺等底物作用,释放出H2O2,当底物为腐胺时,最适浓度为5mmolL-1,Km值为0.5mmolL-1,最适pH为7.0,最适温度为40°C.在非酶系统中,该酶可与NBT溶液反应,呈现紫色,并随时间延长而加深.经SDS板状不连续聚丙烯酰胺凝胶电泳,得该酶亚基分子量为8.3×104. 相似文献
29.
本文介绍了在HT-6B上使用的一套五道外差接收机系统,它用于该装置的ECE信号测量,该系统具有研究等离子体温度参数的时空演化能力,空间分辨可达0.5cm,时间分辨达50μs。它还具有沿装置小半径垂直中心弦力向观察ECE信号的能力。因而,可以配合逐点扫描纵场,使系统具有频谱测量的性能,且可用于研究低杂波驱动等离子体中高能电子的性质及其分布。 相似文献
30.
Cu(phen)22+与6-巯基嘌呤及DNA间的相互作用 总被引:3,自引:0,他引:3
在Tris-NaCl(pH=7.2)缓冲溶液中,应用伏安法、电子吸收光谱分析、溴化乙锭荧光分析、粘度测量和琼脂糖凝胶电泳等技术研究了Cu(phen)2^2+(phen=1,10-邻菲咯啉)与6-巯基嘌呤(6-MP)及DNA间的相互作用。结果表明,Cu(phen)2^2+与6-MP发生了明显的相互作用,其作用产物不仅与小牛胸腺DNA具有更强的相互作用,并且在H2O2和抗坏血酸存在下对质粒pBR322 DNA具有更强的断裂能力,与DNA的作用模式可能为部分插入模式。 相似文献