全文获取类型
收费全文 | 922篇 |
免费 | 86篇 |
国内免费 | 23篇 |
专业分类
电工技术 | 1篇 |
综合类 | 53篇 |
化学工业 | 589篇 |
金属工艺 | 17篇 |
机械仪表 | 3篇 |
建筑科学 | 6篇 |
矿业工程 | 8篇 |
能源动力 | 9篇 |
轻工业 | 164篇 |
水利工程 | 1篇 |
石油天然气 | 86篇 |
武器工业 | 1篇 |
无线电 | 6篇 |
一般工业技术 | 78篇 |
冶金工业 | 2篇 |
原子能技术 | 2篇 |
自动化技术 | 5篇 |
出版年
2024年 | 1篇 |
2023年 | 10篇 |
2022年 | 13篇 |
2021年 | 29篇 |
2020年 | 29篇 |
2019年 | 20篇 |
2018年 | 10篇 |
2017年 | 44篇 |
2016年 | 40篇 |
2015年 | 28篇 |
2014年 | 46篇 |
2013年 | 66篇 |
2012年 | 75篇 |
2011年 | 56篇 |
2010年 | 40篇 |
2009年 | 52篇 |
2008年 | 41篇 |
2007年 | 55篇 |
2006年 | 67篇 |
2005年 | 47篇 |
2004年 | 43篇 |
2003年 | 39篇 |
2002年 | 28篇 |
2001年 | 13篇 |
2000年 | 21篇 |
1999年 | 17篇 |
1998年 | 19篇 |
1997年 | 14篇 |
1996年 | 19篇 |
1995年 | 14篇 |
1994年 | 7篇 |
1993年 | 5篇 |
1992年 | 8篇 |
1991年 | 1篇 |
1990年 | 5篇 |
1989年 | 3篇 |
1988年 | 2篇 |
1983年 | 1篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1951年 | 1篇 |
排序方式: 共有1031条查询结果,搜索用时 875 毫秒
1.
2.
Marina Hovjecki Zorana Miloradovic Vladislav Rac Predrag Pudja Jelena Miocinovic 《Journal of texture studies》2020,51(4):680-687
Acid gels and yoghurts were made from goat milk that was heated at 72°C/30 s, 85°C/5 min, and 95°C/5 min, followed by acidification with starter culture at 43C until pH 4.6. The rheological and textural properties of acid gels and yoghurts were analyzed using dynamic low amplitude oscillatory rheology and back extrusion texture analysis, respectively. The effect of goat milk heat treatment on the mean casein micelle diameter and protein profile was also determined by dynamic light scattering and SDS PAGE electrophoresis, respectively. The shortest gelation and fermentation time was recorded for yoghurt prepared from milk heated at 85°C/5 min. Also, the pH of gelation, the storage moduli (G′) and yield stress were higher for this yoghurt, compared with the other two. Textural properties of goat milk yoghurts such as firmness and consistency were strongly affected by milk heat treatment, and the highest values were recorded for yoghurt produced from milk preheated at 85°C/5 min, as well. The largest casein micelles were measured after 85°C/5 min treatment and their size decreased at higher temperature, despite higher denaturation of whey proteins at the most intense heat regime, indicating the structure changes that influence on the acid gelation. 相似文献
3.
Rational Design of Polymeric Hybrid Micelles with Highly Tunable Properties to Co‐Deliver MicroRNA‐34a and Vismodegib for Melanoma Therapy 下载免费PDF全文
Hanmei Li Yao Fu Ting Zhang Yanping Li Xiaoyu Hong Jiayu Jiang Tao Gong Zhirong Zhang Xun Sun 《Advanced functional materials》2015,25(48):7457-7469
A polymeric hybrid micelle (PHM) system with highly tunable properties is reported to co‐deliver small molecule and nucleic acid drugs for cancer therapy; this system is structurally simple and easy‐to‐fabricate. The PHM consists of two amphiphilic diblock copolymers, polycaprolactone‐polyethylenimine (PCL‐PEI) and polycaprolactone‐polyethyleneglycol (PCL‐PEG). PHMs are rationally designed with different physicochemical properties by simply adjusting the ratio of the two diblock copolymers and the near neutral PHM‐2 containing a low ratio of PCL‐PEI achieves the optimal balance between high tumor distribution and subsequent cellular uptake after intravenous injection. Encapsulating Hedgehog (Hh) pathway inhibitor vismodegib (VIS) and microRNA‐34a (miR‐34a) into PHM‐2 generates the VIS/PHM‐2/34a co‐delivery system. VIS/PHM‐2/34a shows synergistic anticancer efficacy in murine B16F10‐CD44+ cells, a highly metastatic tumor model of melanoma. VIS/PHM‐2/34a synergistically attenuates the expression of CD44, a vital receptor indicating the metastasis of melanoma. Intriguingly, inhibiting Hh pathway by VIS is accompanied by downregulation of CD44 expression, revealing that Hh signaling might be an upstream regulator of CD44 expression in melanoma. Thus, co‐delivery of miR‐34a and VIS demonstrates great potential in cancer therapy, and PHM offers a structurally simple and highly tunable platform for the co‐delivery of small molecule and nucleic acid drugs in tumor combination therapy. 相似文献
4.
在酸性体系中采用阴极扫描伏安和计时电流等电化学测试方法,研究添加十二烷基硫酸钠(SDS)对铜电沉积过程的影响机理。结果表明:SDS的添加使沉积电位正移,降低了阴极极化。SDS浓度低于临界胶束浓度1g/L时,铜的成核弛豫时间延长,形核速率降低。SDS浓度高于临界胶束浓度时,形成SDS球状胶束,铜的成核弛豫时间减少,形核速率加快。铜晶核形成过程符合Scharitker?Hill 三维成核/生长机制,当SDS为1g/L时,在-0.2V的低过电位区,铜结晶按渐进成核方式进行,在-0.23--0.28V的高过电位区,铜结晶按瞬时成核方式进行。而当SDS为0.5g/L时,铜在-0.2V--0.25V的低电位区和在-0.28V的高电位区均符合渐进成核。 相似文献
5.
运用自制的可视化实验设备,进行了表面活性剂吐温(T40,1×10-3mol/L;T40,2×10-3mol/L;T40/T80(1∶1),1×10-3mol/L)在瓦斯水合过程中的影响研究,结合煤层高压注水中添加表面活性剂R1-89的现场研究,分析了表面活性剂在瓦斯水合3阶段的主要作用.认为在煤层注水阶段表面活性剂的加入降低了液体表面张力和注水压力,使注水速度加快,煤体得到均匀润湿;在水合物诱导阶段表面活性剂的胶束化增加了瓦斯气体的溶解度,促进了气体在溶液中过饱和,推动了水合物晶核生长,缩短了诱导时间;在水合物生长阶段,表面活性剂胶束对溶于其中的气体分子和吸附于其周围的水分子的束缚作用,相当于降低了体系的温度,改变了水合物生成热力学条件. 相似文献
6.
7.
Leqi Cui Ketinun Kittipongpittaya D. Julian McClements Eric A. Decker 《Journal of the American Oil Chemists' Society》2014,91(11):1931-1937
Phospholipids are important minor components in edible oil that play a role in lipid oxidation. Surface active phospholipids have an intermediate hydrophilic–lipophilic balance value, which allows them to form association colloids such as reverse micelles in bulk oil. These association colloids can influence lipid oxidation since they create lipid–water interfaces where prooxidants and antioxidants can interact with triacylglycerols. In this study, we examined the formation of reverse micelles in a stripped oil system by dioleoyl phosphoethanolamine (DOPE) and the effect of these physical structures on lipid oxidation kinetics. The critical micelle concentration (CMC) of DOPE was approximately 200 µmol/kg oil at 45 °C. Oxidation kinetics studies showed that DOPE was prooxidative when it was above its CMC (400 and 1,000 µM), reducing the lag phase from 14 days (control) to 8 days. The addition of combinations of DOPE and dioleoyl phosphocholine (DOPC) resulted in formation of mixed micelles with a CMC of 80 µmol/kg oil at 45 °C. These mixed micelles were also prooxidative when concentrations (100 and 500 µM) were above the CMC, decreasing the lag phase from 14 to 8 days. These findings provide a better understanding of the role of phospholipids in lipid oxidation of edible oil and could contribute to better antioxidant solutions. 相似文献
8.
Ketinun Kittipongpittaya Atikorn Panya Leqi Cui David Julian McClements Eric Andrew Decker 《Journal of the American Oil Chemists' Society》2014,91(11):1955-1965
Association colloids formed by surface active minor components play an important role in the oxidative stability of bulk oils. To imitate the formation of nanostructures in refined oils, multiple surface active minor components including phospholipids, free fatty acids, diacylglycerols and sterols were added to stripped corn oil. The critical micelle concentration (CMC) of the mixed components was determined. The impact of mixed minor components at below and above their CMC on oxidative stability of bulk oil and on antioxidant activity of α-tocopherol and Trolox was investigated. The CMC of the mixed surface active components in bulk oil was 20 µmol/kg oil in the presence of 383 ± 2 ppm of water. 1,2-Dioleoyl-sn-glycero-3-phosphocholine (DOPC) played an important role on the formation of association colloids since it was the most important component in forming the association colloids as confirmed by CMC and fluorescence probe studies. The association colloids formed by the mixed components showed prooxidative activity in bulk oil as determined by monitoring the formation of lipid hydroperoxide and hexanal. The activity of α-tocopherol or Trolox was not changed by mixed components association colloids. These results suggest that association colloids both physically and chemically impacted the oxidative stability and activity of antioxidants in bulk oil. 相似文献
9.
10.
Louis P. Jackson Ralph Andrade Ian Pleasent Brian P. Grady 《Journal of surfactants and detergents》2014,17(5):911-917
Aqueous solutions of sodium tetradecanoate (S14C) and sodium dodecanoate (S12C) were used to evaluate complicated precipitation phenomena and to monitor the effects of bulk pH adjustments on surface tension and critical micelle concentrations (CMC) determination from surface tension plots. Limited solubilities of pure sodium n-alkyl carboxylates in solution near the CMC have been reported previously many times. In this study, precipitation encountered with solutions prepared from vender-supplied S12C was eliminated through additional purification. As sodium alkyl carboxylates discussed in the literature are commonly used as received from the manufacture without additional purification, the wide range of reported CMC values as well as precipitation near the CMC for S12C are also likely due to impurities. However, complete solubility for S14C solution concentrations near the reported CMC values was not obtained through additional purification of purchased material. Hence, some CMC values reported in the literature for S14C should be reconsidered, as discontinuities in the slope of surface tension versus concentration plots are likely caused by the formation of a precipitate not micelle aggregation. In addition and in agreement with other studies, solution pH adjustments revealed a minimum surface tension for maximum solubility near the pK a value for S14C. 相似文献