全文获取类型
收费全文 | 32850篇 |
免费 | 3822篇 |
国内免费 | 2473篇 |
专业分类
电工技术 | 1861篇 |
技术理论 | 1篇 |
综合类 | 2344篇 |
化学工业 | 7050篇 |
金属工艺 | 4106篇 |
机械仪表 | 1287篇 |
建筑科学 | 1299篇 |
矿业工程 | 742篇 |
能源动力 | 1286篇 |
轻工业 | 2230篇 |
水利工程 | 553篇 |
石油天然气 | 1474篇 |
武器工业 | 441篇 |
无线电 | 3279篇 |
一般工业技术 | 5348篇 |
冶金工业 | 1779篇 |
原子能技术 | 1865篇 |
自动化技术 | 2200篇 |
出版年
2024年 | 72篇 |
2023年 | 779篇 |
2022年 | 1019篇 |
2021年 | 1330篇 |
2020年 | 1350篇 |
2019年 | 1245篇 |
2018年 | 1246篇 |
2017年 | 1383篇 |
2016年 | 1389篇 |
2015年 | 1298篇 |
2014年 | 1760篇 |
2013年 | 2226篇 |
2012年 | 2108篇 |
2011年 | 2428篇 |
2010年 | 1769篇 |
2009年 | 1800篇 |
2008年 | 1752篇 |
2007年 | 2158篇 |
2006年 | 1876篇 |
2005年 | 1609篇 |
2004年 | 1437篇 |
2003年 | 1166篇 |
2002年 | 879篇 |
2001年 | 809篇 |
2000年 | 652篇 |
1999年 | 590篇 |
1998年 | 454篇 |
1997年 | 440篇 |
1996年 | 382篇 |
1995年 | 288篇 |
1994年 | 256篇 |
1993年 | 218篇 |
1992年 | 180篇 |
1991年 | 154篇 |
1990年 | 128篇 |
1989年 | 120篇 |
1988年 | 81篇 |
1987年 | 46篇 |
1986年 | 42篇 |
1985年 | 45篇 |
1984年 | 35篇 |
1983年 | 25篇 |
1982年 | 44篇 |
1981年 | 25篇 |
1980年 | 6篇 |
1979年 | 10篇 |
1978年 | 7篇 |
1977年 | 5篇 |
1976年 | 5篇 |
1951年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
聚醚醚酮及其复合材料的摩擦学研究进展 总被引:11,自引:0,他引:11
评述了聚醚醚酮(PEEK)及其复合材料的摩擦磨损性能,在滑动过程中形成的摩擦转移膜以及磨屑的研究,总结了聚合物基复合材料摩擦学研究的一般方法及规律,介绍了关于用PEEK复合材料制造的轴承,齿轮等进行的摩擦学研究,以及等离子体表面处理和颗粒增强对PEEK及其复合材料摩擦学性能的影响。 相似文献
92.
93.
Using the focal mechanisms of earthquakes taken place from 1950 to 1996, the type and direction of principal strains were established, which made it possible to determine the volume stress-strain state of the south-east flank of the Baikal rift zone on the basis of the inverse problem solution. The variations in the stress-strain fields and spatial distribution of the stored potential energy density were found by the displacements of the daylight surface points in Tunkinsk geodetic proving ground in 1975 - 1986. 相似文献
94.
应用统计控制图法,选用平均值——标准差、平均值——极差控制图法,控制24^#坝粘土填筑干密度值及施工偶然异常波动,早期提出警报,以保证土坝的施工质量。 相似文献
95.
Novel polyurethane insulating coatings were prepared from the reaction of glycerin‐terminated polyurethane prepolymers (GPUPs) and a blocked isocyanate curing agent (BIC). The GPUPs were prepared from the reaction of one equivalent of polycaprolactone polyol (CAPA 210) with an excess amount of 4,4′‐methylene bis(phenyl isocyanate) (MDI) and subsequent reaction of the NCO‐terminated polyurethane with glycerin. The BIC was prepared from the reaction of trimethylol propane (TMP), toluene diisocyanate (TDI) and N‐methylaniline (NMA). The polyols and curing agent were characterized by conventional methods while the curing condition was optimized via gel content measurements. The curing kinetics of the polyurethane coating were investigated and the kinetic parameters derived. The crosslink densities of the samples were determined via the equilibrium swelling method, using the Flory–Rehner equation. The relationships between the crosslink density and the electrical, physical, mechanical and dynamic mechanical properties of the coatings were also studied. Copyright © 2005 Society of Chemical Industry 相似文献
96.
RRN Sailaja 《Polymer International》2005,54(12):1589-1598
Lignin was graft copolymerized with methyl methacrylate using manganic pyrophosphate as initiator. This modified lignin was then blended (up to 50 wt%) with low density polyethylene (LDPE) using a small quantity of poly[ethylene‐co‐(glycidyl methacrylate)] (PEGMA) compatibilizer. The mechanical properties of the blend were substantially improved by using modified lignin in contrast to untreated lignin. Differential scanning calorimetry studies showed loss of crystallinity of the LDPE phase owing to the interaction between the blend components. Thermogravimetric analysis showed higher thermal stability of modified lignin in the domain of blend processing. This suggested that there is scope for useful utilization of lignin, which could also lead to the development of eco‐friendly products. Copyright © 2005 Society of Chemical Industry 相似文献
97.
高压脉冲放电处理含氰废水的影响因素探讨 总被引:6,自引:0,他引:6
焦化废水中含有大量的氰化物,必须采取有效措施进行去除,传统去除方法运行成本高、操作复杂。提出了用高压毫微秒脉冲产生的非平衡等离子体处理含氰废水的方法,对其影响因素pH值、放电时间、气流量、放电条件等进行了大量的实验研究,结果表明:溶液初始pH值为9.09,放电2 h,放电电压46 kV时氰化物的去除率最高可达93.2%,氰化物质量浓度可降至0.26 mg/L。实验对比了放电与不放电氰化物的去除效果:相同条件下放电后氰化物的去除率大大提高,为焦化废水中氰化物的去除提出了一种新的方法。 相似文献
98.
A self‐consistent texture model is implemented in the finite‐element code ABAQUS/Explicit®. Hardening of the slip systems is described by evolution laws for dislocation densities, and the Bauschinger effect is included. With these ingredients the cold rolling of an IF‐steel is simulated and the evolution of texture and anisotropy is examined. The use of the dislocation based hardening law is found to have a significant effect on the evolution of the anisotropic yield surface, but only very little influence on the texture. Furthermore, the hardening model is used to investigate the evolution of dislocation densities in differently oriented grains during plane strain compression. It is found that the dislocation density varies greatly depending on orientation, an observation which can help to explain the orientation dependence of recrystallization. 相似文献
99.
Gasification of polyethylene (PE) pellet was studied using atmospheric argon-steam plasma generated by microwave discharge and the feasibility of the process was examined. The experimental results showed that additional steam to argon plasma promoted the weight decrease of PE and enhanced the production of H2, CO, CO2 and CH4. The results confirmed that the treatment of plastics with the steam plasma was effective to obtain synthesis gas. 相似文献
100.
Tb3+,Mn2+作为激活剂的PDP绿色荧光粉的研究 总被引:1,自引:1,他引:0
分别介绍了以Mn^2+和Tb^3+作为激活中心的PDP用硅酸盐体系、铝酸盐体系、硼酸盐体系和磷酸盐等体系绿色荧光粉的研究现状。在以Mn^2+作为发光中心的绿粉中,目前研究主要集中在通过调整Mn^2+的离子浓度、添加其他杂质,探索使用新的基质材料,或是使用不同的合成技术等方法来改进其余辉时间过长、易时效劣化以及形貌上的不足。在以Tb^3+作为激活中心的绿粉中,为了获取在真空紫外激发条件下高的发光效率,则主要围绕寻找在VUV区域内有强吸收的基质和能够有效进行能量传递的稀土敏化剂,以及利用量子剪裁效应来使得荧光粉发光量子效率大于1等方面进行。 相似文献