全文获取类型
收费全文 | 22965篇 |
免费 | 4649篇 |
国内免费 | 5727篇 |
专业分类
化学 | 16924篇 |
晶体学 | 730篇 |
力学 | 1430篇 |
综合类 | 494篇 |
数学 | 2985篇 |
物理学 | 10778篇 |
出版年
2024年 | 86篇 |
2023年 | 391篇 |
2022年 | 982篇 |
2021年 | 1030篇 |
2020年 | 1045篇 |
2019年 | 1055篇 |
2018年 | 939篇 |
2017年 | 1108篇 |
2016年 | 1080篇 |
2015年 | 1319篇 |
2014年 | 1615篇 |
2013年 | 2072篇 |
2012年 | 2163篇 |
2011年 | 2218篇 |
2010年 | 1823篇 |
2009年 | 1760篇 |
2008年 | 1980篇 |
2007年 | 1678篇 |
2006年 | 1552篇 |
2005年 | 1302篇 |
2004年 | 1006篇 |
2003年 | 766篇 |
2002年 | 672篇 |
2001年 | 657篇 |
2000年 | 663篇 |
1999年 | 428篇 |
1998年 | 243篇 |
1997年 | 194篇 |
1996年 | 208篇 |
1995年 | 155篇 |
1994年 | 138篇 |
1993年 | 149篇 |
1992年 | 118篇 |
1991年 | 116篇 |
1990年 | 81篇 |
1989年 | 103篇 |
1988年 | 65篇 |
1987年 | 54篇 |
1986年 | 57篇 |
1985年 | 49篇 |
1984年 | 39篇 |
1983年 | 44篇 |
1982年 | 36篇 |
1981年 | 19篇 |
1980年 | 21篇 |
1979年 | 14篇 |
1978年 | 9篇 |
1977年 | 7篇 |
1957年 | 5篇 |
1936年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
Song C Wang D Gu G Lin Y Yang J Chen L Fu X Hu Z 《Journal of colloid and interface science》2004,272(2):340-344
Silver-coated poly(methyl acrylic acid) (PSA) core-shell colloid particles were prepared by an in situ chemical reduction method. Crystalline silver/titania composite hollow spheres were obtained by coating the as-prepared PSA/silver particles with an amorphous titania layer and subsequently calcining in Ar atmosphere. SEM and TEM investigation indicated that the size of the as-prepared PSA/silver and PSA/silver/TiO(2) core-shell particles and silver/titania composite hollow particles was fairly uniform and the wall thickness of the hollow spheres was in the range of 40-80 nm. UV-vis absorption spectra were recorded to investigate their optical properties. 相似文献
82.
83.
84.
ZHANG Yifeng GUO Hong ZHANG Guangming YAN Xiuyun YIN Shougen ZHANG Zhengpu Institute of Taitai Pharmaceutical Co. Ltd Shengzhen China State Key Lab. of Functional Polymeric Materials for Adsorption Separation Institute of Polyme 《Chinese Journal of Reactive Polymers》2002,(1)
1. INTRODUCTION Fig.1 The Chemical Structure of Milupeinan As a new type of antibiotics Milupeinan, not only possesses antibacterial activities against a wide range of Gram-positive and Gram-negative bacteria, but also higgh stability under th… 相似文献
85.
Amide-water mixtures are studied by all-atom molecular dynamics (MD) simulations and the relative temperature-dependent NMR experiment. The weak C-H...O contacts are found in the amide-water systems theoretically and experimentally. The statistical results of the average numbers of hydrogen bonds indicate that the methyl groups in amide molecules represent different capabilities in forming the weak C-H...O contacts. The statistics also imply that the C-H...O contacts are more obvious in the amide-rich region than those in the water-rich region. The temperature-dependent NMR spectra are also adopted to investigate the weak C-H...O contacts in the amide-water systems. The relative chemical shifts of the methyl groups are in good agreement with the MD simulations. 相似文献
86.
CUI Wei HUANG Lei LI Wei WANG Li-ping 《高等学校化学研究》2006,22(2):236-238
Introduction S Adenosylmethionine(SAM)isabiologicallyac tivecompoundwidelydistributedinthebodytissues andfluids.Itisinvolvedinanumberofbiochemical reactions.Asamethylgroupdonor,itisimportantin transmethylationreactions,whichcontributestothe synthesesofsuc… 相似文献
87.
设计合成了一系列新的席合物3a~3p, 其结构经 1H NMR, IR, LC/MS确证. 用化合物对小鼠耳部巴豆油炎症影响的炎症模型测定化合物3a~3i的生物活性, 结果表明, 化合物3d, 3f, 3g可明显抑制巴豆油致小鼠耳部炎症. 其抑制率分别为19.5%, 27.6%, 16.1%. 相似文献
88.
应用分子动力学模拟了25 ℃和50 ℃时新型室温熔盐二(三氟甲基磺酸酰)亚胺锂[LiN(SO2CF3)2, LiTFSI]与尿素(摩尔比为1:3.6)体系的结构与动力学性质. 在两个温度下体系的微观结构基本相同, Li+的配位数约为5, 且都是与溶剂和阴离子中的氧原子发生配位. 对TFSI-的研究表明, 每个TFSI-只提供四个氧中的一个与Li+配位; 而且在Li+的配位层中, TFSI-具有顺、反和gauche 等不同的构象, 并且不同构象出现的几率会随着温度的改变而改变. 相似文献
89.
90.
Bitao Su Ke Wang Jie Bai Hongmei Mu Yongchun Tong Shixiong Min Shixiong She Ziqiang Lei 《Frontiers of Chemistry in China》2007,2(4):364-368
Fe3+-doped TiO2 composite nanoparticles with different doping amounts were successfully synthesized using sol-gel method and characterized
by X-ray diffraction (XRD), transmission electron microscopy (TEM) and ultravioletvisible spectroscopy (UV-Vis) diffuse reflectance
spectra (DRS). The photocatalytic degradation of methylene blue was used as a model reaction to evaluate the photocatalytic
activity of Fe3+/TiO2 nanoparticles under visible light irradiation. The influence of doping amount of Fe3+ (ω: 0.00%–3.00%) on photocatalytic activities of TiO2 was investigated. Results show that the size of Fe3+/TiO2 particles decreases with the increase of the amount of Fe3+ and their absorption spectra are broaden and absorption intensities are also increased. Doping Fe3+ can control the conversion of TiO2 from anatase to rutile. The doping amount of Fe3+ remarkably affects the activity of the catalyst, and the optimum efficiency occurs at about the doping amount of 0.3%. The
appropriate doping of Fe3+ can markedly increase the catalytic activity of TiO2 under visible light irradiation.
__________
Translated from Journal of Northwest Normal University (Natural Science), 2006, 42(6): 55–56 [译自: 西北师范大学学报(自然科学版)] 相似文献