全文获取类型
收费全文 | 9809篇 |
免费 | 934篇 |
国内免费 | 267篇 |
专业分类
电工技术 | 104篇 |
综合类 | 1129篇 |
化学工业 | 2276篇 |
金属工艺 | 132篇 |
机械仪表 | 243篇 |
建筑科学 | 3925篇 |
矿业工程 | 749篇 |
能源动力 | 100篇 |
轻工业 | 495篇 |
水利工程 | 155篇 |
石油天然气 | 481篇 |
武器工业 | 12篇 |
无线电 | 108篇 |
一般工业技术 | 485篇 |
冶金工业 | 222篇 |
原子能技术 | 131篇 |
自动化技术 | 263篇 |
出版年
2024年 | 12篇 |
2023年 | 99篇 |
2022年 | 193篇 |
2021年 | 275篇 |
2020年 | 257篇 |
2019年 | 229篇 |
2018年 | 202篇 |
2017年 | 279篇 |
2016年 | 305篇 |
2015年 | 302篇 |
2014年 | 563篇 |
2013年 | 638篇 |
2012年 | 789篇 |
2011年 | 798篇 |
2010年 | 543篇 |
2009年 | 566篇 |
2008年 | 516篇 |
2007年 | 625篇 |
2006年 | 568篇 |
2005年 | 495篇 |
2004年 | 398篇 |
2003年 | 352篇 |
2002年 | 289篇 |
2001年 | 269篇 |
2000年 | 224篇 |
1999年 | 190篇 |
1998年 | 152篇 |
1997年 | 255篇 |
1996年 | 109篇 |
1995年 | 102篇 |
1994年 | 66篇 |
1993年 | 57篇 |
1992年 | 64篇 |
1991年 | 45篇 |
1990年 | 38篇 |
1989年 | 40篇 |
1988年 | 36篇 |
1987年 | 20篇 |
1986年 | 10篇 |
1985年 | 4篇 |
1984年 | 5篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 15篇 |
1979年 | 7篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1963年 | 1篇 |
1951年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
《Geotextiles and Geomembranes》2022,50(3):535-544
Soil column is often investigated in the improvement of dredged slurries. Different from the smear zone, the soil column forms gradually and has extremely low permeability. This study presents an analytical solution for soil consolidation considering the increasing radius of the soil column and time-dependent discharge capacity. Based on the solution, the influence of the radius' increase on the consolidation behavior is found significant when the soil column has low permeability and large final radius, and the increase of formation time can lead to the increase of consolidation speed and final consolidation degree. 相似文献
2.
3.
Mahmoud Ghazavi Ahad Ehsani Yamchi Javad Nazari Afshar 《Geotextiles and Geomembranes》2018,46(3):312-318
In very soft soils, the bearing capacity of stone columns may not improve significantly due to very low confinement of the surrounding soil. Therefore, they may be reinforced with geosynthetics by using vertical encasement or horizontal layers. Very limited studies exist on horizontally reinforced stone columns (HRSCs). In this research, some large body laboratory tests have been performed on horizontally reinforced stone columns with diameters of 60, 80, and 100?mm and groups of stone columns with 60?mm diameter. Results show that the bearing capacity of stone columns increases by using horizontally reinforcing layers. Also, they reduce lateral bulging of stone columns by their frictional and interlocking effects with stone column aggregates. Finally, numerical analyses were carried out to study main affecting parameters on the bearing capacity of HRSCs. Numerical analysis results show that the bearing capacity increases considerably with increasing the number of horizontal layers and decreasing space between layers. 相似文献
4.
Xiang-feng KONG Xing-xing JIANG Sheng-guo XUE Ling HUANG William HARTLEY Chuan WU Xiao-fei LI 《中国有色金属学会会刊》2018,28(3):534-541
Bauxite residue, a highly saline solid waste produced from digestion of bauxite for alumina production, is hazardous to the environment and restricts vegetation establishment in bauxite residue disposal areas. A novel water leaching process proposed here was used to investigate the dynamic migration and vertical distribution of saline ions in bauxite residue. The results show that water leaching significantly reduced the salinity of bauxite residue, leaching both saline cations Na+, K+, Ca2+ and anions CO2?3, SO2?4, HCO?3. Na+ and K+ migrated from 40–50 to 20–30 cm of the column, presenting a high migration capacity. The migration capacity of Ca2+ was lower and accumulated at 30–40 cm of the column. CO2?3 initially distributed at 20–30 cm of the column, subsequently transported to 30–40 cm of the column, and finally returned to 20–30 cm of the column along with evaporation. SO2?4 was originally distributed at 40–50 cm, but finally migrated to 20–30 cm of the column. Nevertheless, HCO?3 remained at the bottom of the column, and its migratory was less affected by evaporation. 相似文献
5.
为了避免和减轻由过大隔震层位移引起的损害,对基础隔震框架结构装设调频液柱阻尼器(tuned liquid column damper,简称TLCD)后混合系统的减振效果进行研究。建立了单层和多层混合控制系统在地震作用下的运动方程,采用TLCD-结构体系转化为调频质量阻尼器(tuned mass damper,简称TMD)-结构体系的等效方法,利用TMD参数优化公式,得到单个TLCD初始设计参数,并采用状态空间方程得到多个TLCD最优设计参数。通过对某8层基础隔震结构进行模拟,证明了该理论设计方法的合理性。该混合结构不仅可以减小隔震层位移和加速度,而且对上部结构位移和加速度反应都能更有效的控制。 相似文献
6.
Bin Guo Huimin Wang Danan Lan Xiaomin Pang Yiming Li Haiyan Liu Hongyuan Yan Ligai Bai 《应用聚合物科学杂志》2019,136(25):47683
Three temperature-sensitive monolithic columns were prepared by atom transfer radical polymerization and oxidation–reduction method using the initiator systems of CCl4/FeCl2, BPO/DMA, and APS/TEMED, respectively. The three monoliths were characterized by scanning electron microscopy, nitrogen adsorption, and thermogravimetric analysis. The obtained monolithic columns were used as on-line solid phase extraction sorbent coupled with high-performance liquid chromatography for the enrichment of β-sitosterol. By comparing some influencing factors on the adsorption, the optimum temperature-sensitive monolithic column which was initiated by CCl4/FeCl2 was selected for enrichment of β-sitosterol from plant oil. The maximum adsorption capacity of the monolith for β-sitosterol was 10.0031 mg/g. The limit of detection and limit of quantitation were 0.039 and 0.13 mg/mL, respectively. The recovery was in the range of 90.21–98.26%. The results showed that the monolith had better selectivity for β-sitosterol and could be used for enrichment of β-sitosterol in food samples. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47683. 相似文献
7.
Mass transfer parameters are necessary for the design of absorption and desorption processes in packed columns. To determine the effective interfacial area and liquid side mass transfer parameters, CO2 absorption and desorption are frequently used. Reliable analytics for concentration determination are essential to obtain correct results. In this work two methods of CO2 liquid phase analysis are compared: first, the back titration of unreacted NaOH after prior precipitation of the bound CO2; secondly, the inorganic carbon analysis with a commercial inorganic carbon analyzer. 相似文献
8.
Stone columns, which are frequently employed to stabilize the liquefiable soil, are susceptible to accumulation of soil particles. The progressive accumulation of the soil particles causes clogging of the stone column which decreases its drainage capacity. The stone column can be encased with geotextile to sustain its long term drainage function. The encasement prevents the movement of the soil particles into the stone pores. In the present paper, a mathematical model is presented to assess the filtration performance of the geotextile encasement to prevent the clogging. The filtration capacity of the geotextile is related to its maximum pore size, porosity and soil characteristics. It is observed that the encased stone column dissipates the excess pore pressure at a faster rate compared to the stone column without encasement. The peak maximum excess pore water pressure (Umax) is not significantly affected due to selection of the opening size of the geotextiles for single earthquake. However, the opening size can significantly affect the peak Umax value for multiple earthquakes. Depending on the capture coefficient of the stone column, the clogging can be fully prevented for higher hydraulic gradient if geotextile with maximum opening size in between D10 to D5 is used as encasement. 相似文献
9.
进行了圆柱振动台试验,对模型的加速度反应数据进行获取。试验表明,随着地震的加速度峰值的不断增加,圆柱顶部加速度极值不断增加。柱顶的加速度响应有着增大的趋势,且极值比输入的加速度的极值有一定的放大。 相似文献
10.