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1.
聚烯烃催化剂硅胶载体的制备和表征 总被引:3,自引:0,他引:3
采用并流共沉淀法制备了适用于聚烯烃催化剂的硅胶载体,为减少颗粒的聚集,在制备过程中添加一种表面活性剂。利用透射电子显微镜(TEM)、比表面积测定(BET)和X射线粉末衍射(XRD)法对制备的硅胶载体进行了表征;考察了在制备硅胶载体过程中原料硅酸钠溶液的浓度、溶液pH以及焙烧温度对产物硅胶载体的物理性能的影响。实验结果表明,硅酸钠溶液的浓度影响硅胶的初始粒子的大小,溶液pH直接影响硅酸钠的水解速率,焙烧温度影响硅胶的孔结构和比表面积。当硅酸钠溶液的浓度为0.2mol/L、溶液pH为8-9、反应温度为70℃、焙烧温度为700℃时,硅胶载体的BET比表面积为242.22m2/g、最可几孔径为16.45 nm、堆密度为0.492 1g/mL,与进口硅胶(Silica Gel 955)的物理性能相近。 相似文献
2.
聚烯烃/纳米SiO2复合材料研究进展 总被引:4,自引:0,他引:4
论述了纳米SiO2的表面处理方法、复合材料的制备技术及其力学和光学性能。表明纳米SiO2分散于聚烯烃(PP、HDPE)中,可以提高基体的韧性、强度和模量。以纳米SiO2作为填料的聚乙烯棚膜,呈现优良的红外线吸收性能和可见光透过性能。为此,纳米SiO2可作为一种聚乙烯农膜的新型保温剂。 相似文献
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In this work, a ternary blend of polyolefin elastomer (POE), lauric acid (LA), and poly(ε-caprolactone) (PCL) with triple-shape memory effect (triple-SME) is reported. LA and PCL exhibit distinct thermal transitions and construct two reversible switching networks capable of fixing and releasing different temporary shapes under a mild condition. The ternary blend shows excellent triple-shape memory properties and good toughness. Besides, the permanent shape can be reconfigured by a simple thermal treatment. These particular features make the novel blend a competitive candidate for diverse applications. And the creative combination of crystalline small molecule and semicrystalline polymer expands the freedom for producing triple-shape memory polymers (triple-SMPs). 相似文献
6.
简述了大分子表面改性剂添加到聚烯烃基体中时接触介质的诱导作用和聚烯烃基体结晶的异质排斥作用及其相对分子质量、链节的柔顺性和与基体的相容性对其表面富集的影响。提出大分子表面改性剂设计合成的基本原则:化学结构和使用环境相匹配、憎水基功能团和亲水基功能团相适应、使用效率和功能持久性相平衡。介绍了大分子表面改性剂合成的主要方法。 相似文献
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Migration kinetics of straight-chain oligomers and antioxidants from several polyolefins at different temperatures into various solvents have been studied by radioactive tracer techniques. Anhydrous ethanol appears to be a well suited food-oil or liquid-fat simulant for extracting different types of migrants from polyolefins. Pure and mixed triglycerides are also good oil or fat simulants, but the triglycerides offer no simpler analytical procedures than the use of oil or fat themselves. n-Octanol may also be considered as a reasonable oil or fat simulant; however, its action depends somewhat on the choice of migrants. The accelerating action of n-heptane over that of oil or simulants is quantitatively demonstrated. The accelerating effects are greater for migration systems with lower diffusion coefficients. The diffusion coefficients for migration into n-heptane are about 20 times greater than the diffusion coefficients into ethanol or oil for otherwise identical migration systems yielding diffusion coefficients of about 10?7 cm2s?1 into oil or ethanol. For systems yielding diffusion coefficients into oil or ethanol of about 10?12 cm2s?1, the corresponding diffusion coefficients into n-heptane are about 1000 times greater. The molecular weight distributions (MWDs) of the n-heptane and ethanol extracts of polyolefins have been analysed. n-Heptane can not only accelerate the migration of the individual migrant but also remove oligomer species that are slightly soluble or present at low levels in the oil or simulant extracts. 相似文献
9.
用轻质CaCO3填充新型聚烯烃弹性体POE,研究了填充体系的力学性能和流变性能随CaCO3含量变化的规律.发现随CaCO3填充量增加至40份,体系拉伸强度下降,拉断伸长率变化不大,冲击回弹性下降,邵氏硬度上升.POE8150/CaCO3的拉伸强度、邵氏硬度比POE8003/CaCO3小,前者的拉断伸长率、冲击回弹性大于后者.POE8150/CaCO3的流动曲线表明体系的整体流动性较好,可以较快地剪切速率挤出,CaCO3的加入使流动性变差. 相似文献
10.
Yurun Yang Yongmin Huang Yonglin Chen Dening Wang Honglai Liu Chunpu Hu 《应用聚合物科学杂志》2004,91(5):2984-2991
A series of polyurethane (PU) films made from toluene diisocyanate (TDI), 1,4‐butanediol (BDO), and hydroxyl‐terminated polybutadiene (HTPB), hydroxyl terminated polybutadiene/styrene (HTBS), or hydroxyl terminated polybutadiene/acrylonitrile (HTBN) was synthesized by solution polymerization. The absorption of benzene vapor was found mainly in the soft phase. The equilibrium adsorption (M∞) was reduced with increasing hard segment content for all the PUs. The values of M∞ were in the sequence of HTBN‐PUs > HTBS‐PUs > HTPB‐PUs, which could be explained by the different interaction parameters between soft segments and benzene. The HTBN‐PU film showed the lowest degree of phase segregation and had more hard segments intermixed in the soft phase, restricting the movement of soft segments, and therefore resulted to non‐Fickian behavior, while the HTPB‐PU is antithetical. FTIR and atomic force microscopy were utilized to identify the hydrogen bonding behavior and morphology change of the PU films before and after the absorption of benzene vapor. The tensile strength of the HTBN‐PUs showed a greater decrease than that of HTBS‐PUs and HTPB‐PUs after absorbing benzene vapor. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2984–2991, 2004 相似文献