全文获取类型
收费全文 | 791篇 |
免费 | 62篇 |
国内免费 | 26篇 |
专业分类
电工技术 | 1篇 |
综合类 | 49篇 |
化学工业 | 235篇 |
金属工艺 | 3篇 |
机械仪表 | 21篇 |
建筑科学 | 232篇 |
矿业工程 | 4篇 |
能源动力 | 8篇 |
水利工程 | 4篇 |
石油天然气 | 292篇 |
一般工业技术 | 24篇 |
冶金工业 | 4篇 |
原子能技术 | 1篇 |
自动化技术 | 1篇 |
出版年
2024年 | 1篇 |
2023年 | 10篇 |
2022年 | 13篇 |
2021年 | 14篇 |
2020年 | 16篇 |
2019年 | 24篇 |
2018年 | 30篇 |
2017年 | 45篇 |
2016年 | 30篇 |
2015年 | 6篇 |
2014年 | 37篇 |
2013年 | 70篇 |
2012年 | 31篇 |
2011年 | 34篇 |
2010年 | 46篇 |
2009年 | 31篇 |
2008年 | 55篇 |
2007年 | 94篇 |
2006年 | 45篇 |
2005年 | 30篇 |
2004年 | 61篇 |
2003年 | 23篇 |
2002年 | 14篇 |
2001年 | 11篇 |
2000年 | 17篇 |
1999年 | 8篇 |
1998年 | 13篇 |
1997年 | 5篇 |
1996年 | 5篇 |
1995年 | 7篇 |
1994年 | 3篇 |
1993年 | 2篇 |
1992年 | 13篇 |
1991年 | 2篇 |
1990年 | 2篇 |
1989年 | 3篇 |
1988年 | 6篇 |
1987年 | 4篇 |
1985年 | 7篇 |
1984年 | 5篇 |
1983年 | 3篇 |
1982年 | 3篇 |
排序方式: 共有879条查询结果,搜索用时 0 毫秒
21.
采用裂解色谱(PY-GC-MS)、电子顺磁共振波谱(EPR)和红外光谱(FTIR)等技术手段,分析了Estonia油页岩中干酪根及其热解产物的结构特性,研究了不同温度下中间产物与最终产物的关联性.结果显示:油页岩热解符合干酪根热解为中间产物热沥青,热沥青再热解为页岩油、干馏气和半焦等产物反应路径,中间产物热沥青的生成趋... 相似文献
22.
Jungang Lu Jie Ma Li Wang Huanxu Zhang Xianli Zou Hui Han 《Petroleum Science and Technology》2016,34(5):464-470
Bitumen's influence on reservoir properties and hydrocarbon accumulation in Santai area was studied by experiment measures and geochemical evidences. The porosity and permeability of the sandstones containing bitumen increased significantly by dissolving experiments, implying that bitumen strongly influences the reservoir properties. The analysis reveals that there were two stages of hydrocarbon accumulation. In the first stage oil migrated into coarse-grained sandstone and then degraded to bitumen, which deteriorated the reservoir properties. The second stage oil had to migrate into fine-grained sandstones, or the residual pores of the bitumen-containing coarse-grained sandstone. Exploration in this area should avoid the bitumen distribution zone. 相似文献
23.
天津市和悦花园住宅小区一期高层工程屋面采用平坡结合的形式,坡屋面选用了永得维拉誖沥青波形瓦。该瓦自防水,抗风揭,且施工效率高,建筑装饰效果好。 相似文献
24.
Petroleum bitumen in the emulsified state is widely used as a binder in road and civil construction. Along with traditional quality parameters of bitumen emulsions the particle size is considered to be very important characteristic. The particle size of the dispersed phase affects the setting rate and viscosity of bitumen emulsions. The complete data on the particles size distribution can be obtained using such technical methods as light scattering and microscopy. In the study bitumen emulsions with three types of surfactants (cationic, nonionic, zwitterionic) have been prepared and their viscosity and decay index have been determined. The emulsions also have been studied with a microscope, as well as by the method of dynamic light scattering. The dynamics of particle size changes of the bitumen emulsions has been compared with the dynamics of the change in the basic parameters of the emulsions, such as viscosity and decay index, and the correlation between them has been found. Thus, using a modern laser and optical equipment, it is possible to estimate the quality of emulsions and, if necessary, to correct their composition. 相似文献
25.
Pratik Nayak 《International Journal of Pavement Engineering》2017,18(7):595-607
Recycling of highway materials is an effort to preserve the natural environment, reduce waste and provide a cost-effective way for construction of highways. The reclaimed asphalt pavement (RAP) contains stiffened binder caused by loss of volatile materials and oxidation. Hence, the addition of high amount of the RAP to asphalt mix may make it prone to fatigue failure. Due to this reason, addition of RAP to asphalt mixture in substantial amount has been a challenge so far. Therefore, ‘rejuvenators’ which are supposed to restore chemical and physical properties of the aged asphalts are used effectively in asphalt mixture. In this study, two locally available oils, i.e. pongamia oil (locally known as Karanja oil) derived from the seeds of Pongamia pinnata and a composite rejuvenator made of castor oil and coke oven gas condensate have been explored for rejuvenating the aged binder. The rheological properties of aged binder and rejuvenated binders were studied using a dynamic shear rheometer. From the various rheological tests conducted, it was found that certain proportion of pongamia oil as well as composite castor oil was able to impart desirable rutting as well as fatigue performance for the rejuvenated binder samples. The thermal analysis carried out using thermogravimetric analysis ensured adequate thermal stability for the binder specimens treated with these oils. In terms of binder performances, it was found that these oils could be considered as suitable rejuvenators for effectively restoring properties of the aged binder. Performance studies on RAP mixes may be extended for recommending these two oils as rejuvenators for hot mix pavement recycling. 相似文献
26.
天津滨海新区临港热源厂一混凝土烟道因烟气腐蚀,造成烟道严重渗漏。经试验,SSE-C301喷涂速凝橡胶沥青防腐涂膜对该烟道内的腐蚀成分有很好的抵抗作用,因而被选做主要维修材料。速凝橡胶沥青涂料通过1.5 MPa以上的喷涂压力,完全覆盖了该烟道内墙面砌块接缝,从而保证了在未进行抹灰找平的砌块墙体上施工防腐涂层的质量;涂料3~5 s内速凝固化的特点,确保了侧面喷涂不发生流淌,从而也使侧面涂膜的成膜质量和厚度的均匀性得到了保障。 相似文献
27.
G. P. Kayukova А. V. Vakhin S. M. Petrov S. A. Sitnov 《Petroleum Science and Technology》2017,35(16):1680-1686
This work is devoted to studying the possibility of producing bitumen for road construction by using vacuum residue >420°C of heavy oil of the Ashal'chinskoe field in and natural asphaltite Spiridonovskoe field from Permian deposits in Tatarstan. The effect of natural asphaltite as a solid disperse phase element on the structural and group composition of the residual heavy oil product and its malacometrical qualities (penetration, extensibility, softening point, resistance to aging and adhesion) is revealed. The production of samples of compounded bitumen production was carried out by introducing the required amount of the shredded asphaltite to deasphaltizat vacuum residue of heavy oil and heating their mixture to 220°С with vigorous stirring. Changes in the composition and physical and chemical properties of deasphalting the residual heavy oil product, associated with the amount of injected asphaltite, showed the possibility of production of modified bitumen with better adhesion properties that correspond to road bitumen. 相似文献
28.
29.
30.
转相法低温丁苯胶乳改性乳化沥青的制备 总被引:1,自引:0,他引:1
采用转相法低温制得了性能良好的丁苯胶乳改性乳化沥青,研究了乳化剂等对沥青乳液稳定性的影响,并讨论了改性沥青的部分性能。结果表明,使用质量分数为2.8%的十六烷基三甲基氯化铵/烷基聚氧乙烯基双季铵盐/聚氧化乙烯烷基醚(质量比1∶1∶3)复合乳化剂,沥青乳液的稳定性能满足T0655—1993标准的要求;Ca2 、NH4 的浓度分别小于1.44,2.34mmol/L时对乳液的稳定性影响不大;当丁苯胶乳与沥青乳液质量比为1∶8时,试样的黏结强度、拉伸强度、扯断伸长率分别达到0.21MPa、0.34MPa、210%,性能达到JC/T408—1996标准的要求。 相似文献