全文获取类型
收费全文 | 75篇 |
免费 | 17篇 |
国内免费 | 29篇 |
专业分类
化学 | 62篇 |
数学 | 28篇 |
物理学 | 31篇 |
出版年
2023年 | 1篇 |
2022年 | 3篇 |
2021年 | 2篇 |
2020年 | 1篇 |
2019年 | 1篇 |
2018年 | 1篇 |
2016年 | 3篇 |
2015年 | 5篇 |
2014年 | 4篇 |
2013年 | 12篇 |
2012年 | 9篇 |
2011年 | 10篇 |
2010年 | 7篇 |
2009年 | 8篇 |
2008年 | 11篇 |
2007年 | 4篇 |
2006年 | 4篇 |
2005年 | 6篇 |
2004年 | 2篇 |
2003年 | 8篇 |
2002年 | 3篇 |
2001年 | 1篇 |
2000年 | 2篇 |
1999年 | 4篇 |
1997年 | 1篇 |
1996年 | 3篇 |
1993年 | 2篇 |
1992年 | 1篇 |
1988年 | 1篇 |
1981年 | 1篇 |
排序方式: 共有121条查询结果,搜索用时 15 毫秒
61.
Chattarin Ruchawapol Man Yuan Si-Min Wang Wen-Wei Fu Hong-Xi Xu 《Molecules (Basel, Switzerland)》2021,26(20)
Herpesviruses establish long-term latent infection for the life of the host and are known to cause numerous diseases. The prevalence of viral infection is significantly increased and causes a worldwide challenge in terms of health issues due to drug resistance. Prolonged treatment with conventional antiviral drugs is more likely to develop drug-resistant strains due to mutations of thymidine nucleoside kinase or DNA polymerase. Hence, the development of alternative treatments is clearly required. Natural products and their derivatives have played a significant role in treating herpesvirus infection rather than nucleoside analogs in drug-resistant strains with minimal undesirable effects and different mechanisms of action. Numerous plants, animals, fungi, and bacteria-derived compounds have been proved to be efficient and safe for treating human herpesvirus infection. This review covers the natural antiherpetic agents with the chemical structural class of alkaloids, flavonoids, terpenoids, polyphenols, anthraquinones, anthracyclines, and miscellaneous compounds, and their antiviral mechanisms have been summarized. This review would be helpful to get a better grasp of anti-herpesvirus activity of natural products and their derivatives, and to evaluate the feasibility of natural compounds as an alternative therapy against herpesvirus infections in humans. 相似文献
63.
通过溶胶-凝胶法与半连续种子乳液聚合法相结合,以正硅酸乙酯(TEOS)制备的纳米SiO2为核,以甲基丙烯酸甲酯(MMA)、丙烯酸丁酯(BA)和甲基丙烯酸三氟乙酯(3FMA)的共聚物P(MMA/BA/3FMA)为壳,合成了SiO2@P(MMA/BA/3FMA)核-壳结构纳米复合粒子.为防止纳米SiO2的团聚,提高其与共聚物的结合力,用乙烯基三甲氧基硅烷(VTMS)对纳米SiO2进行改性.通过红外光谱、透射电子显微镜、动态激光散射粒度仪、静态接触角测试仪、X射线光电子能谱分析和热重分析等表征了乳液结构及膜性能.结果表明,获得的复合纳米粒子呈现粒径分布为40~50 nm的核-壳结构球型颗粒.由于含氟官能团的迁移使得氟元素在膜-空气界面富集,有效降低了膜的表面自由能.当3FMA质量分数达到25%时,膜表面自由能达到最低值(23.13 mN/m).随着3FMA含量的增加,共聚物初始热分解温度由350℃提高到390℃. 相似文献
64.
65.
Zang GL Sheng GP Li WW Tong ZH Zeng RJ Shi C Yu HQ 《Physical chemistry chemical physics : PCCP》2012,14(6):1978-1984
Urine pretreatment has attracted increasing interest as it is able to relieve the nitrogen and phosphorus overloading problems in municipal wastewater treatment plants. In this study, an integrated process, which combines magnesium ammonium phosphate (MAP) precipitation with a microbial fuel cell (MFC), is proposed for the recovery of a slow-release fertilizer and electricity from urine. In such a two-step process, both nitrogen and phosphorus are recovered through the MAP process, and organic matters in the urine are converted into electricity in the MFCs. With this integrated process, when the phosphorus recovery is maximized without a dose of PO(4)(3-)-P in the MAP precipitation process, removal efficiencies for PO(4)(3)-P and NH(4)(+)-N of 94.6% and 28.6%, respectively, were achieved with a chemical oxygen demand (COD) of 64.9% accompanied by a power output of 2.6 W m(-3). Whereas removal efficiencies for PO(4)(3)-P and NH(4)(+)-N of 42.6% and 40%, respectively, and a COD of 62.4% and power density of 0.9 W m(-3) were obtained if simultaneous recovery of phosphorus and nitrogen was required through dosing with 620 mg L(-1) of PO(4)(3-)-P in the MAP process. This work provides a new sustainable approach for the efficient and cost-effective treatment of urine with the recovery of energy and resources. 相似文献
66.
Fifteen examples are disclosed of efficient In(III)-catalyzed six-membered ring closure leading to bi-, tri-, and tetracyclic products. 相似文献
67.
合成了2个共轭二茂铁席夫碱配合物,用元素分析、红外光谱、紫外光谱、核磁共振等对它们进行了表征及电化学性质 研究,并用X射线衍射测定了它们的晶体结构。配合物1存在反演中心,其晶体属单斜晶系,P21/c空间群。晶体学数据为:a=1.148 5(2) nm,b=0.857 75(17) nm,c=1.194 4(2) nm,β=99.980(5)°,V=1.158 8(4) nm3,Z=2,μ=1.499 mm-1,Dc=1.562 g·cm-3,R1=0.068 9,wR2=0.128 0。 相似文献
68.
69.
Meloxicam is a new non-steroid anti-inflammatory drug (NSAID). In contrast to other NSAIDs currently available,such as piroxicam, tenidap and indomethacin, it appears to have greater inhibitory activity against the inducible isoform of cyclo-oxygenase (COX-2), which is implicated in the inflammatory response,than against the constitutive isoform (COX-1). 相似文献
70.
This paper summarizes the 10th National Undergraduate Chemistry Laboratory Tournament, analyzes the problems existing in current experiment teaching which are reflected in the tournament, and gives some reform suggestions on the basic contents of experiment teaching and the standardization of experiment operation. 相似文献