全文获取类型
收费全文 | 109151篇 |
免费 | 3220篇 |
国内免费 | 1507篇 |
专业分类
电工技术 | 2216篇 |
技术理论 | 3篇 |
综合类 | 3919篇 |
化学工业 | 15633篇 |
金属工艺 | 6470篇 |
机械仪表 | 4627篇 |
建筑科学 | 4459篇 |
矿业工程 | 1297篇 |
能源动力 | 1774篇 |
轻工业 | 5226篇 |
水利工程 | 1681篇 |
石油天然气 | 1781篇 |
武器工业 | 206篇 |
无线电 | 12211篇 |
一般工业技术 | 19458篇 |
冶金工业 | 3712篇 |
原子能技术 | 516篇 |
自动化技术 | 28689篇 |
出版年
2024年 | 94篇 |
2023年 | 423篇 |
2022年 | 700篇 |
2021年 | 1099篇 |
2020年 | 854篇 |
2019年 | 650篇 |
2018年 | 15086篇 |
2017年 | 14097篇 |
2016年 | 10611篇 |
2015年 | 1570篇 |
2014年 | 1404篇 |
2013年 | 1668篇 |
2012年 | 4732篇 |
2011年 | 11050篇 |
2010年 | 9816篇 |
2009年 | 6969篇 |
2008年 | 8129篇 |
2007年 | 9168篇 |
2006年 | 1493篇 |
2005年 | 2494篇 |
2004年 | 2007篇 |
2003年 | 1946篇 |
2002年 | 1325篇 |
2001年 | 725篇 |
2000年 | 898篇 |
1999年 | 795篇 |
1998年 | 671篇 |
1997年 | 519篇 |
1996年 | 544篇 |
1995年 | 395篇 |
1994年 | 329篇 |
1993年 | 257篇 |
1992年 | 218篇 |
1991年 | 155篇 |
1990年 | 86篇 |
1989年 | 88篇 |
1988年 | 78篇 |
1987年 | 38篇 |
1986年 | 33篇 |
1968年 | 43篇 |
1967年 | 33篇 |
1966年 | 42篇 |
1965年 | 44篇 |
1960年 | 30篇 |
1959年 | 35篇 |
1958年 | 37篇 |
1957年 | 36篇 |
1956年 | 34篇 |
1955年 | 63篇 |
1954年 | 68篇 |
排序方式: 共有10000条查询结果,搜索用时 531 毫秒
991.
The ablation in solid-propellant rocket nozzle is a coupling process resulted by chemistry, heat and mass transfer. Based on the heat and mass transfer theory, the aero-thermo-dynamic, and thermo-chemical kinetics, the thermal-chemical ablation model is established. Simulations are completed on the heat flow field and chemical ablation in the nozzle with different concentrations, frequency factors and activation energy of H2. The calculation results show that the concentration and the activation energy of H... 相似文献
992.
ESB通过服务中介者为服务交互双方提供中介服务.针对目前ESB中介实现机制中存在的耦合问题,论文提出了ESB服务中介框架ESB-SMF,对服务中介者的模型进行了改进,并对其运行机制进行阐述,最后给出了服务中介者的Java实现. 相似文献
993.
Summary Polypyrrole (PPy) composite films with different contents of Fe3O4 were prepared by in-situ polymerization of pyrrole in aqueous solutions. The dependence of dc current changes on the response
of the samples exposure to NH3 vapor has been investigated. The results shows the composite films are more stable than the pristine ones after being exposed
to NH3 vapor. Meanwhile, the response time was reduced with increasing the Fe3O4 content in the films. The results might be originated from the structural changes in the PPy films caused by the addition
of Fe3O4. 相似文献
994.
Peter A. Edwards Grant Striemer Dean C. Webster 《Journal of Coatings Technology and Research》2005,2(7):517-527
Glycidyl carbamate chemistry combines the excellent properties of polyurethanes with the crosslinking chemistry of epoxy resins.
Glycidyl carbamate functional oligomers were synthesized by the reaction of polyfunctional isocyanate oligomers and glycidol.
The oligomers were formulated into coatings with several amine functional crosslinkers at varying stoichiometric ratios and
cured at different temperatures. Properties such as solvent resistance, hardness, and impact resistance were dependent on
the composition and cure conditions. Most coatings had an excellent combination of properties. Studies were carried out to
determine the kinetics of the curing reaction of the glycidyl carbamate functional oligomers with multifunctional and model
amines. Detailed kinetic analysis of the curing reactions was also undertaken. The results indicated that the glycidyl carbamate
functional group is more reactive than a glycidyl ether group.
Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, on October 27–29, 2004, in Chicago,
IL. 相似文献
995.
日晷是科学与艺术的结合体.日晷造型日趋多样化,其晷面上的晷影计算更加复杂.根据天文学理论计算太阳高度角和方位角和阴影形成原理,计算日出至日落之间各时刻晷针在晷面上的阴影位置,得出各时刻线的位置.在VC++开发环境下采用OpenGL图形标准,设计并实现了通用日晷三维仿真系统.系统支持不同造型日晷的三维可视化模拟以及时刻线位置模拟数据的可视化分析,并以动画的形式逼真表达一个时段内晷影的运动过程.通过比较分析仿真值与实测值之间的关系,表明整个系统能比较客观地模拟晷影位置,为日晷个性化设计、城市造景规划、科学教研、科普教育提供一个直观、便捷的模拟分析辅助工具. 相似文献
996.
Jae-Wook Lee Kyung-June Hwang Wang-Geun Shim Kyung-Hee Park Hal-Bon Gu Kyu-Hyuk Kwun 《Korean Journal of Chemical Engineering》2007,24(5):847-850
Dye sensitized solar cells (DSSCs) have been receiving significant attention because they have many advantages compared to
conventional organic solar cells. It has been known that the photovoltaic characteristics of DSSC are highly dependent on
the adsorption properties of dyes on TiO2 films. To analyze the surface heterogeneity of TiO2 surfaces, single-phase anatase nanocrystallite titanium films were prepared by sol-gel method using the hydrolysis reaction
of titanium tetraisopropoxide under acidic condition and characterized by XRD, FE-SEM and BET analysis. The adsorption energy
distribution functions were calculated by the generalized nonlinear regularization method. It was found that the shape and
the intensity of the adsorption energy distribution curve determined were highly related with the physical properties (i.e.,
geometrical heterogeneity) and chemical characteristics (i.e., energetic heterogeneity) of nanocrystalline TiO2 for DSSC. 相似文献
997.
通用塑料在阳光作用下都会降解,添加稳定剂可成功地解决此问题。但是,在某些情况下普通的稳定剂不能满足这种要求,这就促进了新的反应型稳定剂的发展。低分子稳定剂的接枝可克服草取问题。研究反应型稳定剂是提高聚合物的耐热性和耐草取性的一种发展趋势。按反应性基团的不同,该类稳定剂可分为乙烯基型、丙烯酰基型和其他类型。文章综述了反应型稳定剂的合成和应用,还介绍了其中一些商业化的品种。 相似文献
998.
999.
Hyun Min Shim Joon Soo Lee Hong Yue Wang Seung Hak Choi Jeong Hoon Kim Hyung Taek Kim 《Korean Journal of Chemical Engineering》2007,24(3):537-541
The main purpose of the study was to develop a model using ASPEN and Excel simulation method to establish optimum CO2 separation process utilizing hollow fiber membrane modules to treat exhaust gas from LNG combustion. During the simulation,
optimum conditions of each CO2 separation scenario were determined while operating parameters of CO2 separation process were varied. The characteristics of hollow fibers membrane were assigned as 60 GPU of permeability and
25 of selectivity for the simulation. The simulation results illustrated that 4 stage connection of membrane module is required
in order to achieve over 99% of CO2 purity and 90% of recovery rate. The resulted optimum design and operation parameters throughout the simulation were also
correlated with the experimental data from the actual CO2 separation facility which has a capacity of 1,000 Nm3/day located in the Korea Research Institute of Chemical Technology. Throughout the simulation, the operating parameters of
minimum energy consumption were evaluated. Economic analysis of pilot scale of CO2 separation plant was done with the comparison of energy cost of CO2 recovery and equipment cost of the plant based on the simulation model.
This work was presented at the 6
th
Korea-China Workshop on Clean Energy Technology held at Busan, Korea, July 4–7, 2006. 相似文献
1000.
Commercial activated carbon (AC) was used as a support either in its original form or after various modifications, giving
diverse textural and surface chemical characteristics. The changes of these properties were monitored by N2 adsorption–desorption isotherms, temperature programmed desorption (TPD) and X-ray photoelectron spectroscopy (XPS). Ag catalysts
were prepared over the AC supports by a conventional wet impregnation method. The catalytic performances of supported Ag/AC
catalysts in the selective oxidation of CO in excess H2 were tested. The results indicate the textural and surface chemical characteristics are responsible for the different catalytic
performances. 相似文献