全文获取类型
收费全文 | 25192篇 |
免费 | 502篇 |
国内免费 | 859篇 |
专业分类
电工技术 | 819篇 |
综合类 | 614篇 |
化学工业 | 2543篇 |
金属工艺 | 905篇 |
机械仪表 | 1421篇 |
建筑科学 | 1697篇 |
矿业工程 | 1367篇 |
能源动力 | 213篇 |
轻工业 | 4538篇 |
水利工程 | 691篇 |
石油天然气 | 775篇 |
武器工业 | 195篇 |
无线电 | 1856篇 |
一般工业技术 | 6275篇 |
冶金工业 | 558篇 |
原子能技术 | 331篇 |
自动化技术 | 1755篇 |
出版年
2024年 | 72篇 |
2023年 | 201篇 |
2022年 | 193篇 |
2021年 | 192篇 |
2020年 | 168篇 |
2019年 | 232篇 |
2018年 | 304篇 |
2017年 | 125篇 |
2016年 | 138篇 |
2015年 | 191篇 |
2014年 | 403篇 |
2013年 | 318篇 |
2012年 | 2094篇 |
2011年 | 2609篇 |
2010年 | 769篇 |
2009年 | 513篇 |
2008年 | 1833篇 |
2007年 | 1739篇 |
2006年 | 1513篇 |
2005年 | 1306篇 |
2004年 | 1149篇 |
2003年 | 975篇 |
2002年 | 847篇 |
2001年 | 768篇 |
2000年 | 827篇 |
1999年 | 589篇 |
1998年 | 429篇 |
1997年 | 393篇 |
1996年 | 364篇 |
1995年 | 402篇 |
1994年 | 347篇 |
1993年 | 310篇 |
1992年 | 389篇 |
1991年 | 373篇 |
1990年 | 354篇 |
1989年 | 275篇 |
1988年 | 236篇 |
1987年 | 287篇 |
1986年 | 283篇 |
1985年 | 273篇 |
1984年 | 255篇 |
1983年 | 197篇 |
1982年 | 227篇 |
1981年 | 190篇 |
1980年 | 159篇 |
1979年 | 130篇 |
1978年 | 76篇 |
1965年 | 47篇 |
1964年 | 40篇 |
1956年 | 40篇 |
排序方式: 共有10000条查询结果,搜索用时 328 毫秒
1.
2.
3.
The separation of iron oxide from banded hematite jasper(BHJ) assaying 47.8% Fe, 25.6% Si O2 and 2.30%Al2O3 using selective magnetic coating was studied. Characterization studies of the low grade ore indicate that besides hematite and goethite,jasper, a microcrystalline form of quartzite, is the major impurity associated with this ore. Beneficiation by conventional magnetic separation technique could yield a magnetic concentrate containing 60.8% Fe with 51% Fe recovery. In order to enhance the recovery of the iron oxide minerals, fine magnetite, colloidal magnetite and oleate colloidal magnetite were used as the coating material. When subjected to magnetic separation, the coated ore produces an iron concentrate containing 60.2% Fe with an enhanced recovery of56%. The AFM studies indicate that the coagulation of hematite particles with the oleate colloidal magnetite facilitates the higher recovery of iron particles from the low grade BHJ iron ore under appropriate conditions. 相似文献
4.
John F.MOXNES Anne K.PRYTZ ?yvind FR?YLAND Stian SKRIUDALEN Steinar B?RVE Gard ?DEG?RDSTUEN 《兵工学报(英文版)》2015,(1):1-9
For the characterization of the behaviors of a metal material in events like expanding warheads, it is necessary to know its strength and ductility at high strain rates, around 104e105/s. The flyer plate impact testing produces the uniform stress and strain rates but the testing is expensive. The Taylor test is relatively inexpensive but produces non-uniform stress and strain fields, and the results are not so easily inferred for material modeling. In the split-Hopkinson bar(SHB), which may be used in compression, tension and torsion testing, the strain rates never exceeds 103/s. In the present work, we use the expanding ring test where the strain rate is 104e105/s. A streak camera is used to examine the expanding ring velocity, and a water tank is used to collect the fragments. The experimental results are compared with the numerical simulations using the hydrocodes AUTODYN, IMPETUS Afea and a regularized smooth particle(RSPH) software. The number of fragments increases with the increase in the expansion velocity of the rings. The number of fragments is similar to the experimental results. The RSPH software shows much the same results as the AUTODYN where the Lagrangian solver is used for the ring. The IMPETUS Afea solver shows a somewhat different fragmentation characteristic due to the node splitting algorithm that induces pronounced tensile splitting. 相似文献
5.
6.
7.
文章采用一种新颖方法对商用IP进行可靠性提升、完善,同时进行容错结构设计,建立了拥有自主知识产权的专用加固型标准单元库,构建了面向空间应用的SoC设计方法与流程,形成了面向空间电子系统的系统集成设计平台,用该技术实现了面向卫星等空间应用的32位嵌入式RISC处理器SoC芯片,获得了一次投片成功。 相似文献
8.
This paper presents an overview of our recent work on the use of soft lithography and two-phase fluid flow to form arrays of droplets. The crucial issues in the formation of stable arrays of droplets and alternating droplets of two sets of aqueous solutions include the geometry of the microchannels, the capillary number, and the water fraction of the system. Glass capillaries could be coupled to the PDMS microchannels and droplets could be transferred into glass capillaries for long-term storage. The arrays of droplets have been applied to screen the conditions for protein crystallization with microbatch and vapor diffusion techniques. 相似文献
9.
A.Molin K.GhanbariAhari B.Josiek J.Molint 《中国耐火材料》2003,12(4):7-10
Physical properties and microstructural evolution on firing of 3 types of bauxite based refractory bricks were carried out using techniques such as porosimetry,XRD and SEM.The groups differed from each other by progressive refining of the matrix or bond phase.It is revealed that such a refinement of the matrix can improve the high temperature properties of the bricks made from poor grade materials. 相似文献
10.
本文讨论一个PCI总线主控制器IP核的设计与验证,描述了该IP核的控制通路和数据通路设计、电路的功能仿真、综合以及验证等过程。结果表明,该IP核在功能和时序上符合PCI技术规范2.2版本,达到了预定的目标。 相似文献