全文获取类型
收费全文 | 11823篇 |
免费 | 749篇 |
国内免费 | 261篇 |
专业分类
电工技术 | 30篇 |
综合类 | 618篇 |
化学工业 | 6698篇 |
金属工艺 | 127篇 |
机械仪表 | 101篇 |
建筑科学 | 409篇 |
矿业工程 | 314篇 |
能源动力 | 64篇 |
轻工业 | 1748篇 |
水利工程 | 17篇 |
石油天然气 | 932篇 |
武器工业 | 39篇 |
无线电 | 63篇 |
一般工业技术 | 1452篇 |
冶金工业 | 140篇 |
原子能技术 | 47篇 |
自动化技术 | 34篇 |
出版年
2024年 | 43篇 |
2023年 | 103篇 |
2022年 | 190篇 |
2021年 | 217篇 |
2020年 | 202篇 |
2019年 | 234篇 |
2018年 | 222篇 |
2017年 | 278篇 |
2016年 | 263篇 |
2015年 | 277篇 |
2014年 | 490篇 |
2013年 | 620篇 |
2012年 | 771篇 |
2011年 | 811篇 |
2010年 | 641篇 |
2009年 | 622篇 |
2008年 | 561篇 |
2007年 | 737篇 |
2006年 | 858篇 |
2005年 | 709篇 |
2004年 | 666篇 |
2003年 | 551篇 |
2002年 | 437篇 |
2001年 | 391篇 |
2000年 | 368篇 |
1999年 | 336篇 |
1998年 | 283篇 |
1997年 | 218篇 |
1996年 | 133篇 |
1995年 | 139篇 |
1994年 | 117篇 |
1993年 | 100篇 |
1992年 | 76篇 |
1991年 | 50篇 |
1990年 | 30篇 |
1989年 | 38篇 |
1988年 | 8篇 |
1987年 | 10篇 |
1986年 | 4篇 |
1985年 | 6篇 |
1984年 | 8篇 |
1983年 | 2篇 |
1982年 | 4篇 |
1981年 | 1篇 |
1980年 | 5篇 |
1978年 | 1篇 |
1951年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 62 毫秒
191.
聚氨酯预聚体——可聚合乳化剂用于MMA乳液聚合动力学及聚合稳定性研究 总被引:1,自引:0,他引:1
将合成的聚氨酯预聚体可聚合乳化剂(APUA)用于甲基丙烯酸甲酯(MMA)乳液聚合体系中,研究了不同引发剂体系和乳化剂对聚合体系的聚合稳定性和动力学影响,并与SDS乳化剂进行了对照。结果显示,用油溶性引发剂(AIBN)和水溶性引发剂(K2S2O8)都能引发该体系的聚合反应,而且聚合速率和转化率都相当高。用AIBN作引发剂时,APUA和SDS两种乳化所对应的动力学曲线不同,但APUA比SDS的聚合速率大得多,其分别类似于微乳液聚合(miniemulsion)和微悬浮聚合(microsuspention),且聚合过程中会产生一定的凝胶。当乳化剂APUA用量适合时,凝胶量极少,聚合体系是稳定的;而当用K2S2O8作引发剂时,两乳化剂对应动力学曲线相似,聚合过程不产生凝胶。但当引发剂用量较大并以APUA作乳化剂时,在聚合过程中会出现全部粒子突然粗化现象,而以SDS作乳化剂没有出现这一现象。 相似文献
192.
Valter Castelvetro Cinzia De Vita Giacomo Giannini Simone Giaiacopi 《应用聚合物科学杂志》2006,102(4):3083-3094
The evolution of the main colloidal parameters in the seeded starved‐feed semi‐continuous emulsion polymerization of butyl methacrylate (BMA) was investigated, with the main purpose of assessing the effectiveness of the semi‐empirical relationship S = K · SS · ΔA/AS as a tool to define the surfactant/monomer feed ratio (∝ K) best suited to achieve a target particle size. In particular, the effect of the type and amount of surfactant [i.e., anionic, sodium dodecyl sulfate (SDS), or nonionic, Brij 58P] added during the semi‐continuous stage was considered. Coagulum formation was never observed under the adopted experimental conditions. To detect the occurrence of secondary nucleation or particle aggregation, or both, the particle size and number of particles, the surface tension and the particle surface coverage ratio were correlated. The best results were obtained with SDS and 0.8 ≤ K ≤ 3. In fact, under the selected experimental conditions, only with SDS did the number of particles remain nearly constant throughout the polymerization at the value defined by the seed latex; the particle size distribution was highly monodisperse, and the final particle diameter closely matched the calculated one (~ 120 nm). The above semi‐empirical relationship based on the adjustable parameter K was validated by running test polymerizations aimed at lattices with well‐defined particle size. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3083–3094, 2006 相似文献
193.
194.
195.
丙烯酸改性聚氨酯的合成与性能的研究 总被引:4,自引:0,他引:4
采用聚丙烯酸酯与聚氨酯共混、以水性聚氯酯为种子乳液进行丙烯酸种子乳液聚合以及水性聚氨酯与丙烯酸接枝共聚3种方法分别得到丙烯酸改性水性聚氯酯,通过激光散射粒径仪测定乳胶粒的粒径、乳胶膜的透明性、傅里叶变换红外光谱(FTIR)结构分析以及扫描电镜(SEM)对乳胶膜结构和表面形貌进行分析。结果表明:采用种子乳液聚合反应和接枝反应所得到的丙烯酸改性水性聚氯酯乳液乳胶粒粒径比水性聚氨酯的粒径显增大,表现出良好的相容性;由种子乳液聚合和接枝聚合制备的丙烯酸改性水性聚氯酯胶膜中颗粒与颗粒之间结合紧密,表面光亮、透明。 相似文献
196.
197.
采用半连续乳液聚合的方法合成聚醋酸乙烯乳液。通过对乳液的粒子形态、压缩剪切强度、粘度、冻融稳定性的分析,讨论了不同性质的聚乙烯醇作为保护胶体,对聚醋酸乙烯乳液胶粘剂性能的影响。 相似文献
198.
Bhuvanesh Gupta Jns Hilborn Christopher Plummer Isabelle Bisson Peter Frey 《应用聚合物科学杂志》2002,85(9):1874-1880
Graft polymerization of acrylic acid onto plasma‐treated poly(ethylene terephthalate) (PET) films was used to prepare surfaces suitable for collagen immobilization by dip‐coating. Such surfaces could be used as matrices for smooth muscle cell cultures in tissue engineering. Contact angle measurements showed that plasma‐treated and grafted PET films undergo considerable surface reorganization during storage under ambient conditions. However, after collagen immobilization the contact angle remained relatively stable. The amount of collagen initially attached to the film surface increased with increasing poly(acrylic acid) graft density, but subsequent washing in water led to significant collagen loss. This loss could nevertheless be substantially reduced by thermal crosslinking of the collagen in the range 110–130 °C. Atomic force microscopy (AFM) observations suggested that the washed crosslinked collagen has a very similar structure to that of the un‐crosslinked collagen. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1874–1880, 2002 相似文献
199.
200.
Nutthakan Pongrakananon Nathaporn Somrang Worakanya Visitsart Pitt Supaphol Manit Nithitanakul Brian P. Grady 《应用聚合物科学杂志》2004,91(4):2216-2222
The effect of methyl acrylate content in ethylene–methyl acrylate–acrylic acid (E–MA–AA) terpolymers and acrylic acid content in ethylene–acrylic acid (E–AA) copolymers was investigated in blends of these two materials. The E–MA–AA terpolymer with 8 mol % methyl acrylate was not miscible with any E–AA material no matter what the AA content, whereas the terpolymer with only about 2 mol % methyl acrylate was miscible, at least to some extent, with the E–AA copolymer at high acrylic acid contents. Evidence supporting this conclusion derived from gloss, differential scanning calorimetry testing, and dynamic mechanical measurements. For the E–AA polymer material with the highest acid content, there was a synergistic effect for some properties at low added amounts of E–MA–AA copolymer; the tensile strength and hardness were 10% higher than values for the E–AA copolymer, even though the E–AA copolymer was much stiffer. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2216–2222, 2004 相似文献