全文获取类型
收费全文 | 351篇 |
免费 | 12篇 |
国内免费 | 5篇 |
专业分类
化学 | 53篇 |
晶体学 | 1篇 |
力学 | 10篇 |
数学 | 54篇 |
物理学 | 67篇 |
综合类 | 183篇 |
出版年
2024年 | 1篇 |
2023年 | 5篇 |
2022年 | 1篇 |
2021年 | 4篇 |
2020年 | 1篇 |
2019年 | 3篇 |
2018年 | 3篇 |
2017年 | 3篇 |
2016年 | 4篇 |
2015年 | 5篇 |
2014年 | 11篇 |
2013年 | 30篇 |
2012年 | 16篇 |
2011年 | 19篇 |
2010年 | 21篇 |
2009年 | 25篇 |
2008年 | 14篇 |
2007年 | 20篇 |
2006年 | 22篇 |
2005年 | 21篇 |
2004年 | 18篇 |
2003年 | 12篇 |
2002年 | 8篇 |
2001年 | 20篇 |
2000年 | 6篇 |
1999年 | 6篇 |
1998年 | 10篇 |
1997年 | 11篇 |
1996年 | 4篇 |
1995年 | 8篇 |
1994年 | 3篇 |
1993年 | 6篇 |
1992年 | 6篇 |
1991年 | 8篇 |
1990年 | 1篇 |
1989年 | 3篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1980年 | 1篇 |
1976年 | 1篇 |
排序方式: 共有368条查询结果,搜索用时 15 毫秒
361.
362.
S. -D. Cheng Y. Zhou C. H. Kam Y. L. Lam Y. C. Chan W. X. Que W. S. Gan 《Fiber and Integrated Optics》2001,20(1):45-52
Thin films of lithium tantalate have been derived on SiO2/Si substrate by sol-gel method. The sol is prepared by mixing LiOC2H5 and Ta(OC2H5)5. The film is deposited by spincoating and annealing at 600°C. The film is characterized by means of X-ray diffraction, atomic force microscopy,and the m-line technique.The experimental results show that the film has crystallized into the pure trigonal phase and it is microsopically continuous and uniform. The crystalline size ranges from about 33nm to 96nm. The refractive index of the film is measured to be 1.84 at the wavelength of 633nm and the film is found to support several guiding modes at this wavelength. 相似文献
363.
每球得分制对中国男排技战术发展的影响 总被引:1,自引:0,他引:1
排球竞赛规则的每次修改 ,对排球技战术的发展产生深远的影响 .每球得分制的实行 ,无疑也会促进排球技战术的创新和提高 .本文分析了每球得分制对排球技战术中一攻及防守反击的成功率、发球的攻击性与稳定性以及攻防的均衡性等方面所提出的新要求 ,找出了中国男排目前与这种新要求之间尚存的差距以及为赶超世界强队应采取的对策 相似文献
364.
《Arabian Journal of Chemistry》2023,16(4):104565
This paper aims to propose a multicriteria decision analysis (MCDA) method to evaluate and select solvent in a dispersive liquid-liquid microextraction (DLLME) approach. The DLLME is applied to the determination of itraconazole and hydroxy itraconazole in plasma by high performance liquid chromatography with fluorescence detection (HPLC-FLD). To achieve this goal, extraction efficiency, chromatographic resolution, and greenness of solvent were identified as the three indicators in MCDA. Then, Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) was employed to evaluate and select the solvent. Weight assignment was set up by integrating the subjective scoring from experienced analysts and the objective approach using Shannon’s entropy weight method. Under chosen parameters (extraction solvent: 1-decanol 40 μL, dispersing solvent: methanol 400 μL), the method was validated satisfactorily and applied successfully to the analysis of itraconazole and hydroxy itraconazole in real human plasma samples. The results show that the comprehensive weighted TOPSIS analysis is a promising tool to choose experimental conditions toward an integrative goal. It can provide analysts with a decision making reference to maintain a balance between the analytical performance and eco-friendliness. 相似文献
365.
季建华 《西昌学院学报(自然科学版)》2001,(2)
电视编辑是电视节目制作中的一个重要环节,它影响着电视节目的质量。本文介绍常见的几种编辑系统配置和两种编辑模式以及电视编辑的技巧和基本原则。 相似文献
366.
草地围栏配套技术是在天然草地急剧退化的前提下开展起来的,是对天然草地实施改良培育的一种行之有效的方法。木里县通过草地围栏配套技术的实施,已取得了显著的经济、社会、生态效益。 相似文献
367.
Jing Zhang Zhiwei Shi Ke Liu Qiyuan Shi Liang Yi Junjie Wang Dr. Lingya Peng Prof. Taihong Liu Prof. Miao Ma Prof. Yu Fang 《Angewandte Chemie (International ed. in English)》2023,62(52):e202314996
Condensed films of functional luminophores dominated by the magnitude and dimensionality of the intermolecular interactions play important roles in sensing performance. However, controlling the molecular assembly and regulating photophysical properties remain challenging. In this study, a new luminophore, ortho-PBI-Au, was synthesized by anchoring a cyclometalated alkynyl-gold(III) unit at the ortho-position of perylene bisimide. An unprecedented T-type packing model driven by weak Au-π interaction and Au−H bonds was observed, laying foundation for striking properties of the luminophore. Controlled assembly of ortho-PBI-Au at the air-water interface, realized using the classical Langmuir–Schaeffer technique, afforded the obtained luminescent films with different packing structures. With an optimized film, sensitive, selective, and rapid detection of a hazardous new psychoactive substance, phenylethylamine (PEA), was achieved. The detection limit, response time, and recovery time were <4 ppb, <1 s, and <5 s, respectively, surpassing the performance of the PEA sensors known thus far. The relationship between the characters of films and the sensing performance was systematically examined by grey relational analysis (GRA). The present study suggests that designing novel molecular aggregation with definite adlayer structure is a crucial strategy to enhance the sensing performance, which could be favorable for the film-based fluorescent sensors. 相似文献
368.
夏明忠 《西昌学院学报(自然科学版)》2000,(3)
采用轮回选择法,以西昌大白豆×昆明白皮豆培育出蚕豆新品种“凉胡6号”(代号91—6)。经1992~1995年参加西昌、会理、会东的区域试验和生产示范种植,表现出耐肥、耐旱、抗倒,抗病性优于对照品种,产量较高.三年分别较对照增产13.65%、21.8%和14.9%,生产试验增产15%以上,生产示范增产17.04%。该品种结荚分布均匀.分枝较多,结荚结实较多,籽粒蛋白质和总糖含量较高。2000年7月6日通过四川省农作物品种审定委员会第四届三次会议审定合格,命名为“凉胡6号”。 相似文献