全文获取类型
收费全文 | 275篇 |
免费 | 50篇 |
国内免费 | 39篇 |
专业分类
化学 | 226篇 |
晶体学 | 5篇 |
力学 | 39篇 |
综合类 | 1篇 |
数学 | 4篇 |
物理学 | 89篇 |
出版年
2024年 | 1篇 |
2023年 | 1篇 |
2022年 | 13篇 |
2021年 | 13篇 |
2020年 | 13篇 |
2019年 | 13篇 |
2018年 | 23篇 |
2017年 | 19篇 |
2016年 | 21篇 |
2015年 | 12篇 |
2014年 | 16篇 |
2013年 | 39篇 |
2012年 | 18篇 |
2011年 | 19篇 |
2010年 | 13篇 |
2009年 | 11篇 |
2008年 | 17篇 |
2007年 | 12篇 |
2006年 | 9篇 |
2005年 | 13篇 |
2004年 | 12篇 |
2003年 | 13篇 |
2002年 | 4篇 |
2001年 | 6篇 |
2000年 | 10篇 |
1999年 | 1篇 |
1998年 | 3篇 |
1997年 | 4篇 |
1996年 | 4篇 |
1994年 | 5篇 |
1990年 | 1篇 |
1985年 | 1篇 |
1983年 | 1篇 |
1980年 | 2篇 |
1979年 | 1篇 |
排序方式: 共有364条查询结果,搜索用时 656 毫秒
111.
通过在有机硅烷中掺杂微纳米级尺度的SiO2颗粒,利用硅烷的水解和聚合成功地制备了1种具有优异耐磨性能和稳定性的超疏水材料.通过该方法所制备的超疏水材料不仅具有良好的耐磨性,而且其超疏水性能可在一定条件下通过表面的磨损得到增强或恢复.该超疏水材料在较苛刻的环境下仍能保持良好的化学稳定性.扫描电镜分析表明贯穿于整个材料且构成材料厚度的微纳米聚合物复合层是赋予该超疏水材料耐磨损性能的主要原因. 相似文献
112.
润湿性是反映储层中油水分布状况的一个重要表征参数,因此研究储层岩石的润湿性对原油开采有着重要的意义. 扩散弛豫二维谱可展示扩散系数与弛豫时间的相关性,并可以对油水的弛豫时间、扩散系数分别进行研究,与核磁共振一维弛豫谱相比极大地提高了区分油水的能力. 该文首先通过多组实验验证扩散-弛豫二维谱可以很好地观测到油水共存状态下玻璃珠表面的润湿性,继而通过对3组人造岩心表面润湿性的测量,获得了人造岩心表面润湿性的信息,解决了此时单独用一维弛豫谱方法难以区分油水的问题. 利用二维谱观察岩石润湿性的研究对油田提高采收率的研究有较大的参考价值. 相似文献
113.
114.
采用分子动力学方法研究了流体在非对称浸润性粗糙纳米通道内的流动与传热过程,分析了两侧壁面浸润性不对称对流体速度滑移和温度阶跃的影响,以及非对称浸润性组合对流体内部热量传递的影响.研究结果表明,纳米通道主流区域的流体速度在外力作用下呈抛物线分布,但是纳米通道上下壁面浸润性不对称导致速度分布不呈中心对称,同时通道壁面的纳米结构也会限制流体的流动.流体在流动过程中产生黏性耗散,使流体温度升高.增强冷壁面的疏水性对近热壁面区域的流体速度几乎没有影响,滑移速度和滑移长度基本不变,始终为锁定边界,但是会导致近冷壁面区域的流体速度逐渐增大,对应的滑移速度和滑移长度随之增大.此时,近冷壁面区域的流体温度逐渐超过近热壁面区域的流体温度,流体出现反转温度分布,流体内部热流逆向传递.随着两侧壁面浸润性不对称程度增加,流体反转温度分布更加明显. 相似文献
115.
纳米流动系统具有高效、经济等优势,在众多领域具有广泛的应用前景.因该类系统具有极高的表面积体积比,致使界面滑移效应对流动具有显著影响.本文采用分子动力学方法以两无限大平行非对称壁面组成的Poiseuille流动为对象,分析了壁面粗糙度与润湿性变化对通道内流体流动的影响.对于不同结构类型的壁面,需要通过水动力位置来确定固液界面位置,准确计算固液界面位置有助于更好地分析界面滑移效应.研究结果表明,上下壁面不对称会引起通道内流场参数分布的不对称,壁面粗糙度及润湿性的变化会影响近壁面附近流体原子的流动特性,由于壁面凹槽的存在,粗糙壁面附近的数密度分布低于光滑壁面一侧.壁面粗糙度及润湿性的变化会影响固液界面位置,肋高变化及壁面润湿性对通道中速度分布影响较大,界面滑移速度及滑移长度随肋高和润湿性的增大而减小;肋间距变化对通道内流体流动影响较小,界面滑移速度和滑移长度基本保持恒定. 相似文献
116.
Wenbo Su Yuetian Liu Huohai Yang Jian Pi Rukuan Chai Changyong Li 《Journal of Dispersion Science and Technology》2019,40(5):695-706
There is not a consistent view about the mechanism of wettability alteration during low salinity water flooding. This paper highlights extensive wettability studies to investigate the wettability alteration on mineralogically different carbonates. Contact angle measurements were conducted to characterize wettability changes quantitatively. The results clearly revealed that wettability of carbonate rock surfaces can be altered to a more water-wet condition by lowering water salinity. The trend of the maximum change of contact angle (MCCA) variation with dolomite/calcite content in the rock is fairly linear under the same salinity, which demonstrates that carbonate minerals can affect rock wettability in a way. Also, the higher calcite content in the rock, the greater MCCA, i.e. the stronger effect of LSWF. Besides, the sensitivity of rock wettability to minerals is different under different salinity conditions. When the salinity is in the range of 2384.6?~?4769.2?mg/L, rock wettability is most sensitive to minerals. The analysis of the effect of ion composition showed that the effect of Ca2+ on wettability alteration is greater than that of Mg2+ at room temperature, and with the increase of the content of calcite in the rock, the effect of Ca2+ is more pronounced than that of Mg2+. 相似文献
117.
118.
Quinn A. Besford Simon Schubotz Soosang Chae Aye B.
zdabak Sert Alessia C. G. Weiss Günter K. Auernhammer Petra Uhlmann Jos Paulo S. Farinha Andreas Fery 《Molecules (Basel, Switzerland)》2022,27(9)
Molecular permeability through polymer brush chains is implicated in surface lubrication, wettability, and solute capture and release. Probing molecular transport through polymer brushes can reveal information on the polymer nanostructure, with a permeability that is dependent on chain conformation and grafting density. Herein, we introduce a brush system to study the molecular transport of fluorophores from an aqueous droplet into the external “dry” polymer brush with the vapour phase above. The brushes consist of a random copolymer of N-isopropylacrylamide and a Förster resonance energy transfer (FRET) donor-labelled monomer, forming ultrathin brush architectures of about 35 nm in solvated height. Aqueous droplets containing a separate FRET acceptor are placed onto the surfaces, with FRET monitored spatially around the 3-phase contact line. FRET is used to monitor the transport from the droplet to the outside brush, and the changing internal distributions with time as the droplets prepare to recede. This reveals information on the dynamics and distances involved in the molecular transport of the FRET acceptor towards and away from the droplet contact line, which are strongly dependent on the relative humidity of the system. We anticipate our system to be extremely useful for studying lubrication dynamics and surface droplet wettability processes. 相似文献
119.
Rui Zhang Zi-jing Zhao Xu Mao Xu-yang Zhu You-feng Cai Heng Wang 《Journal of Dispersion Science and Technology》2018,39(4):571-577
In order to effectively remove the oil-based drilling that remains on the wall of a well and improve the quality of well cementation, flushing fluid must be used to clean it. Due to its excellent flushing effect, microemulsion flushing fluid has been a hot area of research in recent years; the application, however, is limited because of its poor resistance to temperature. In this paper, for the purpose of enhancing the temperature resistance of microemulsion flushing fluid, a new type of comb-shaped trimeric nonionic surfactants N,N-bis(2-stearamidoethyl) stearamide was synthesized, and an anionic–nonionic surfactants composite oil-in-water microemulsion flushing fluid (ANC-MEFF in short) to flush the oil-based drilling was formed. Studies have shown that it has a good flushing effect on oil-based drilling between 20 and 160°C, and its flushing efficiency can reach 93% or even higher. Compared with the CW210L organic phosphorus flushing fluid (Number 1 in short), the flushing efficiency increased by about 20?~?40%, while the microemulsion flushing fluid formed by OP-10 (Number 2 in short) increased by 30% in high temperature, with the application temperature ranging from 20?~?60 to 20?~?160°C, respectively. Additionally, it was found that the microemulsion flushing fluid can make the borehole wall and casing wall change from “oil-wet” into “water-wet”, which is conducive to promoting the quality of cementation between the first and second interfaces intuitively. 相似文献
120.
Novel dual-responsive superhydrophobic hybrid materials,ZnO/SAMs(self-assembled monolayers)of ionic liquids(ILs)with different counter-anions(I-,BF4-,PF6-and Tf2N-),were synthesized and characterized.ZnO nanoparticles were first deposited on glass surfaces to produce roughness.Next,SAMs of fluorinated-alkyl-3-(3-triethoxysilylpropyl)-4,5-dihydro-imidazoliumiodide(abb.[C8Ftespim]I)were grafted onto these surfaces via-Si-O-covalent bonds using self-assembly technique.The Iion could be subsequently exchanged with BF4-,PF6-or Tf2N-through a simple aqueous anion-exchange reaction.The ZnO/ILs hybrid layers were characterized by atomic-force microscopy(AFM),scanning-electron microscopy(SEM)and X-ray photoelectron spectroscopy(XPS).Their wettability was estimated through the measurements of static and dynamic contact angles(CAs).Compared to corresponding films of ZnO/[C8Ftespim]I with CAs 140.7°±2.0°,films of ZnO/[C8Ftespim]PF6 and ZnO/[C8Ftespim]Tf2N showed CAs with 154.0°±2.0°and 152.0°±2.0°,respectively that remained for a long time.This result suggests that anion-exchange can afford superhydrophobic materials.In addition,the wettability of ZnO/[C8Ftespim]X hybrid layers can be reversibly switched by altering ultraviolet(UV)irradiation and dark storage,which shows a photo-induced reversible switch of wettability.The synergistic action of ZnO nanoparticles and SAMs of ILs produced light-anion dual-responsive superhydrophobic materials with ideal stability. 相似文献