全文获取类型
收费全文 | 23093篇 |
免费 | 2073篇 |
国内免费 | 1148篇 |
专业分类
电工技术 | 927篇 |
综合类 | 2398篇 |
化学工业 | 1918篇 |
金属工艺 | 351篇 |
机械仪表 | 470篇 |
建筑科学 | 11597篇 |
矿业工程 | 1304篇 |
能源动力 | 544篇 |
轻工业 | 1004篇 |
水利工程 | 1063篇 |
石油天然气 | 629篇 |
武器工业 | 64篇 |
无线电 | 645篇 |
一般工业技术 | 1388篇 |
冶金工业 | 641篇 |
原子能技术 | 119篇 |
自动化技术 | 1252篇 |
出版年
2024年 | 79篇 |
2023年 | 263篇 |
2022年 | 453篇 |
2021年 | 576篇 |
2020年 | 566篇 |
2019年 | 508篇 |
2018年 | 472篇 |
2017年 | 558篇 |
2016年 | 572篇 |
2015年 | 724篇 |
2014年 | 1579篇 |
2013年 | 1145篇 |
2012年 | 1601篇 |
2011年 | 1680篇 |
2010年 | 1562篇 |
2009年 | 1641篇 |
2008年 | 1488篇 |
2007年 | 1852篇 |
2006年 | 1622篇 |
2005年 | 1365篇 |
2004年 | 1076篇 |
2003年 | 942篇 |
2002年 | 793篇 |
2001年 | 673篇 |
2000年 | 590篇 |
1999年 | 447篇 |
1998年 | 339篇 |
1997年 | 304篇 |
1996年 | 224篇 |
1995年 | 162篇 |
1994年 | 123篇 |
1993年 | 71篇 |
1992年 | 73篇 |
1991年 | 38篇 |
1990年 | 42篇 |
1989年 | 28篇 |
1988年 | 15篇 |
1987年 | 17篇 |
1986年 | 8篇 |
1985年 | 3篇 |
1984年 | 5篇 |
1983年 | 3篇 |
1981年 | 1篇 |
1980年 | 7篇 |
1979年 | 15篇 |
1966年 | 1篇 |
1964年 | 1篇 |
1962年 | 1篇 |
1959年 | 1篇 |
1951年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
11.
Dong Yuancheng Duan Yongsheng Zou Shiying Wang Jian Ye Xingbin Yang Jianxin 《中国炼油与石油化工》2006,(3):27-32
1 Introduction With the successful completion of the construction of the China-Kazakhstan oil pipeline the refinery at Dushanzi Pet- rochemical Company will process the Kazakhstan-Russian mixed crude at full steam starting 2007. The high sulfur, nitro- gen and heavy metals contents in the Kazakhstan-Russian mixed crude would have a serious impact on the secondary processing units of the Dushanzi refinery, in particular on the distillate hydrocracking unit, which mainly operates on vacuum g… 相似文献
12.
双排桩门架—锚杆新型组合支护体系的应用研究 总被引:1,自引:0,他引:1
本文分析了双排桩门架支护结构的受力机理。针对工程实际进行变形分析,提出增设锚杆形成锚杆———双排桩门架式组合支护体系的方法,并与监测数据对比、验证。 相似文献
13.
14.
15.
16.
粉喷桩处理软弱地基在祁临高速公路的应用 总被引:1,自引:1,他引:0
结合工程实例,介绍了粉喷桩的所属类型,粉喷桩对软弱地基加固的原因,所适应土质及加固特点,阐述了祁临十八合同段的粉喷桩施工过程及施工中应注意的若干问题,得出粉喷桩处理不良地基效果良好。 相似文献
17.
A mixed mode digital/analog special purpose VLSI hardware implementation of an associative memory with neural architecture is presented. The memory concept is based on a matrix architecture with binary storage elements holding the connection weights. To enhance the processing speed analog circuit techniques are applied to implement the algorithm for the association. To keep the memory density as high as possible two design strategies are considered. First, the number of transistors per storage element is kept to a minimum. In this paper a circuit technique that uses a single 6-transistor cell for weight storage and analog signal processing is proposed. Second, the device precision has been chosen to a moderate level to save area as much as possible. Since device mismatch limits the performance of analog circuits, the impact of device precision on the circuit performance is explicitly discussed. It is shown that the device precision limits the number of rows activated in parallel. Since the input vector as well as the output vector are considered to be sparsely coded it is concluded, that even for large matrices the proposed circuit technique is appropriate and ultra large scale integration with a large number of connection weights is feasible. 相似文献
18.
G. M. Kulikov S. V. Plotnikova 《International journal for numerical methods in engineering》2002,55(10):1167-1183
The precise representation of rigid body motions in the displacement patterns of curved Timoshenko–Mindlin (TM) shell elements is considered. This consideration requires the development of the strain–displacement relationships of the TM shell theory with regard to their consistency with the rigid body motions. For this purpose a refined TM theory of multilayered anisotropic shells is elaborated. The effects of transverse shear deformation and bending‐extension coupling are included. The fundamental unknowns consist of five displacements and eight strains of the face surfaces of the shell, and eight stress resultants. On the basis of this theory the simple and efficient mixed models are developed. The elemental arrays are derived using the Hu–Washizu mixed variational principle. Numerical results are presented to demonstrate the high accuracy and effectiveness of the developed 4‐node shell elements and to compare their performance with other finite elements reported in the literature. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
19.
柔性桩沉降可靠性的简化分析公式 总被引:1,自引:1,他引:0
本文提出了结合分层的剪切位移法、摄动法和随机场理论来计算柔性桩沉降可靠度的简化方法,并用随机有限元和蒙特卡洛模拟法对此简化模型的精度进行了对比分析,分析结果表明该方法计算简便,精度较高。通过算例发现,在土的变形模量为小变异的情况下,其概率模型对桩的沉降可靠度影响不明显,因此其概率模型可近似采用正态分布;在土的变形模量为大变异的情况下,其概率模型对桩的沉降可靠度影响非常明显,在选择概率模型时要慎重。对于土的变形模量服从对数正态分布的情况,采用将其当量正态化后的中心点法即使在参数大变异的情况下也可以获得理想的计算精度。 相似文献
20.
TeMxMo1.7O mixed oxides (M = V and/or Nb; x = 0-1.7) have been prepared by calcination of the corresponding salts at 600 °C in an atmosphere of N2. A new crystalline phase, with a Te/V/Mo atomic ratio of 1/0.2-1.5/1.7, has been isolated and characterised by XRD and IR spectroscopy. This phase is observed in the TeVMo or TeVNbMo mixed oxide but not in the TeNbMo mixed oxide. The new crystalline phase shows an XRD pattern similar to Sb4Mo10O31 and probably corresponds to the M1 phase recently proposed by Aouine et al. (Chem. Commun. 1180, 2001) to be present in the active and selective MoVTeNbO catalysts. Although these catalysts present a very low activity in the propane oxidation, they are active and selective in the oxidation of propene to acrolein and/or acrylic acid. However, the product distribution depends on the catalyst composition. Acrolein or acrylic acid can be selectively obtained from propene on Nb-free or Nb-containing TeVMo catalysts, respectively. The presence of both V and Nb, in addition to Mo and Te, appears to be important in the formation of acrylic acid from propene. 相似文献