全文获取类型
收费全文 | 167篇 |
免费 | 12篇 |
国内免费 | 122篇 |
专业分类
化学 | 287篇 |
晶体学 | 2篇 |
综合类 | 3篇 |
物理学 | 9篇 |
出版年
2023年 | 2篇 |
2022年 | 9篇 |
2021年 | 33篇 |
2020年 | 11篇 |
2019年 | 4篇 |
2018年 | 3篇 |
2017年 | 9篇 |
2016年 | 8篇 |
2015年 | 9篇 |
2014年 | 10篇 |
2013年 | 10篇 |
2012年 | 22篇 |
2011年 | 8篇 |
2010年 | 2篇 |
2009年 | 13篇 |
2008年 | 16篇 |
2007年 | 8篇 |
2006年 | 20篇 |
2005年 | 19篇 |
2004年 | 12篇 |
2003年 | 16篇 |
2002年 | 7篇 |
2001年 | 11篇 |
2000年 | 8篇 |
1999年 | 3篇 |
1998年 | 7篇 |
1997年 | 5篇 |
1996年 | 8篇 |
1995年 | 3篇 |
1994年 | 4篇 |
1993年 | 1篇 |
排序方式: 共有301条查询结果,搜索用时 15 毫秒
91.
研究了在四氢呋喃溶液中,C60^2-负离子与1,2-二溴丁二酸钠的反应,制得水溶性的衍生物,通过FD-MS.^1HNMR,FT—IR,UV-vis等多种波谱技术对衍生物结构进行了表征,认为该反应为高选择性加成反应;通过衍生物的生物活性实验,证明该衍生物对正常细胞无毒副作用,而对大肠杆菌生长有抑制作用,在5,10μL浓度下表现出对肝癌细胞生长具有弱的抑制作用,证明该衍生物在抑制真菌生长药物和治疗肿瘤药物方面有潜在的应用价值. 相似文献
92.
93.
94.
95.
N-含硒壳聚糖衍生物的合成、表征及其生物活性 总被引:6,自引:0,他引:6
通过壳聚糖分子上的-NH2基与三种有机硒化合物邻甲硒基苯甲硒基苯甲酸对硝基苯酚酯、2-(4-苯甲酸甲酯基)-1,2-苯并异硒唑-3(2H)酮和硒代二乙酸反应,使有机硒分子片接枝到高分子壳聚糖上,合成了三种新的N-含硒壳聚糖衍生物。经元素分析,IR和UV分析表征了其结构。实验结果表明,N-含硒壳聚糖衍生物与预期结构相符。初步动物实验表明其具有一定的生物活性;抗脂质活性和抗肿瘤活性。 相似文献
96.
Klaudia Masztalerz Adam Figiel Anna Michalska-Ciechanowska Aneta Wojdyo Paulina Nowicka Krzysztof Lech 《Molecules (Basel, Switzerland)》2020,25(22)
Osmotic dehydration (OD) performed in concentrated fruit juices used as osmotic solution (OS) comes with some limitations resulting from the material cell structure and is not entirely recognized at the moment. Filtration of the juice could provide some insight into the phenomena occurring throughout the OD. Therefore, the main aim of the study was to recognize the mechanism of selective penetration during OD and evaluate the effect of filtration on physical and chemical properties of osmo-dehydrated material. For this purpose, OD of pumpkin in non-filtrated and filtrated (filters 0.2, 0.45, 0.8, 1.2, 3, 5 and 8 μm) concentrated chokeberry juice was carried out in the study. Moreover, scanning electron microscope (SEM) images were provided. Total phenolic content (TPC) and antioxidant capacity measured by Ferric Reducing Antioxidant Potential (FRAP) and Trolox Equivalent Antioxidant Capacity (TEAC ABTS) of OS and the material were determined. It was found that even though filtration of osmotic solution had a moderate influence on the mass transfer, it greatly affected the chemical composition of dehydrated material. The best option, considering both chemical and physical properties of the dehydrated material, is the use of non-filtrated solution. However, when shorter time of OD is considered, much better results are obtained for filtrated solutions. 相似文献
97.
Shean-Yeaw Ng Chin-Soon Phan Takahiro Ishii Takashi Kamada Toshiyuki Hamada Charles Santhanaraju Vairappan 《Molecules (Basel, Switzerland)》2020,25(22)
Members of the marine soft coral genus Xenia are rich in a diversity of diterpenes. A total of 199 terpenes consisting of 14 sesquiterpenes, 180 diterpenes, and 5 steroids have been reported to date. Xenicane diterpenes were reported to be the most common chemical skeleton biosynthesized by members of this genus. Most of the literature reported the chemical diversity of Xenia collected from the coral reefs in the South China Sea and the coastal waters of Taiwan. Although there was a brief review on the terpenoids of Xenia in 2015, the present review is a comprehensive overview of the structural diversity of secondary metabolites isolated from soft coral genus Xenia and their potent biological activity as reported between 1977 to 2019. 相似文献
98.
以2-氨基-5-巯基-1,3,4-噻二唑和氯乙酸乙酯为原料,水相快速合成中间体(5-氨基-1,3,4-噻二唑-2-基)硫乙酸乙酯,该中间体再与芳氧乙酰氯反应,高产率得到6种目标化合物[5-(芳氧乙酰氨基)-1,3,4-噻二唑-2-基]硫乙酸乙酯(5a-5f)。所有这些化合物都经过了红外、元素分析以及核磁共振氢谱的表征。采用离体平皿法对目标化合物进行了除草活性试验,部分化合物显示出良好的除草活性,而小麦对其耐受。 相似文献
99.
100.