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排序方式: 共有7786条查询结果,搜索用时 31 毫秒
81.
J. H. Kim J. H. Park J. H. Kim T. V. Cao T. Y. Lee H. J. Ban K. Yang H. G. Kim P. B. Ha Y. H. Kim 《中南工业大学学报(英文版)》2009,16(4):621-628
A power management unit (PMU) chip supplying dual panel supply voltage, which has a low electro-magnetic interference (EMI)
characteristic and is favorable for miniaturization, is designed. A two-phase charge pump circuit using external pumping capacitor
increases its pumping current and works out the charge-loss problem by using bulk-potential biasing circuit. A low-power start-up
circuit is also proposed to reduce the power consumption of the band-gap reference voltage generator. And the ring oscillator
used in the ELVSS power circuit is designed with logic devices by supplying the logic power supply to reduce the layout area.
The PMU chip is designed with MagnaChip’s 0.25 μm high-voltage process. The driving currents of ELVDD and ELVSS are more than
50 mA when a SPICE simulation is done. 相似文献
82.
HAN Zuo-zhen YANG Ren-chao FAN Ai-ping CHEN Qing-chun SHAO Yun-tang 《中国矿业大学学报(英文版)》2009,19(1):102-107
Oil reservoirs with secondary bottom water in Ng33 members (in Guantao formation, Paleogene system) of Lin2-6 fault block in Huimin depression (Bohai Bay Basin) have entered the late stage of ultra-high water-containing-exploitation. Oil exploita-tion from vertical wells is becoming more and more inefficient. The reservoir type, with water displacing oil and the remaining oil distribution are specifically studied in order to improve the efficiency of the recovery ratio. An integrated scheme for adjusting horizontal wells has been designed and the key technique of the scheme optimized. The study shows that: 1) the positive rhythm of fluvial depositional features is the internal cause of the flooding of oil reservoirs while water injection, injection-production patterns and accumulative petroleum production are the external causes; 2) oil-water driving patterns have transferred from edge water ad-vancing to bottom-water-coning; distribution of the remaining oil mainly concentrates in the upper rhythm and top of the middle rhythm in Ng33 members; 3) a great deal of remaining oil is enriched in high positions of faults, in axes of tiny structures, in stagna-tion areas among water-injection wells and oil-wells and in tectonic saddle areas with sparse wells. Compared with vertical wells, horizontal wells have advantages such as high recovery, high off-take potential, high critical output, large controlling areas and long time of bottom-water breakthrough. 相似文献
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分析讨论了造型设计的基本概念、美学法则在电子通信设备的具体运用以及电子通信设备具体的造型设计方法,举出了造型设计实例。 相似文献
85.
Ultralight X-type lattice sandwich structure (I): Concept,fabrication and experimental characterization 总被引:1,自引:1,他引:0
ZHANG QianCheng HAN YunJie CHEN ChangQing & LU TianJian State Key Laboratory for Mechanical Behavior of Materials School of Material Science Engineering Xi’an Jiaotong University Xi’an China MOE Key Laboratory for Strength Vibration School of Aerospace Department of Engineering Mechanics AML Tsinghua University Beijing 《中国科学E辑(英文版)》2009,52(8):2147-2154
A new type of ultra-lightweight metallic lattice structure (named as the X-type structure) is reported. This periodic structure
was formed by two groups of staggered struts in the traditional pyramid structure, and fabricated by folding expanded metal
sheet along rows of offset nodes and then brazing the folded structure (as the core) with top and bottom facesheets to form
sandwich panels. The out-of-plane compressive and shear properties of the X-type lattice sandwich structure were investigated
experimentally and compared to those of the sandwich having a pyramidal truss core. It is found that the formation of the
2-dimensional staggered nodes can effectively make the X-type structure more resistant to inelastic and plastic buckling under
both compression and shear loading than the pyramidal lattice truss. Obtained results show that the compressive and shear
peak strengths of the X-type lattice structure are about 30% higher than those of the pyramidal lattice truss having the same
relative density.
Supported by the National Basic Research Program of China (“973” Project) (Grant No. 2006CB601202), the National Natural Science
Foundation of China (Grant Nos. 10632060,10825210), the National “111” Project of China (Grant No. B06024) and the National
High-Tech Research and Development Program of China (“863” Project) (Grant No. 2006AA03Z519) 相似文献
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Coal is a crucial feedstock for South Africa’s unique synfuels and petrochemicals industry and used by Sasol as a feedstock to produce synthesis gas via the Sasol-Lurgi Fixed Bed Dry Bottom (FBDB) gasification process. The ash fusion temperature (AFT) gives detail information on the suitability of a coal source for gasification purposes, and specifically to which extent ash agglomeration or clinkering is likely to occur within the gasifier. Ash clinkering inside the gasifier can cause channel burning and unstable operation.Sasol-Lurgi FBDB gasifiers are currently operated with the philosophy of adding an excess of steam to the process to control the H2/CO ratio of the syngas produced, but indirectly also to control the maximum gasifier temperature below the AFT of the coal. An opportunity exists to increase the AFT of the coal fed to the gasifiers by adding AFT increasing minerals to the coal blend before it is fed into the gasification process. For the aim of this study a South African coal source was investigated, as being used by the gasification operations in Secunda.With the specific aim of this study, to increase the AFT, the determination of the AFT of the coal blends where acidic components such as silica (SiO2), alumina (Al2O3) and titania (TiO2) were added was conducted. The Al2O3 had the biggest and most significant effect on the AFT with the least addition to the coal blend. The effect of SiO2 and TiO2 were very similar, but the effect was much smaller and further Al2O3 was needed to increase the AFT to a similar AFT level in comparison to the SiO2 used. Kaolinite, roof and floor components (containing mainly Al2O3 and SiO2) were also added, also showing an increase in the AFT with up to 4 mass% addition. Another observation was that the AFT was non-additive (not a linear weighted calculated average) and not the weighted average AFT as was expected for the other coal properties such as the ash content, for example. The ash slagging characteristics is a non-additive property of individual coal sources in the blend and therefore difficult to predict.In general it can be concluded that the unique opportunity exists to increase the AFT, was tested, proven and mechanistically outlined in this study on the coal source fed to the Sasol-Lurgi FBDB gasifiers. The AFT can be increased to >1350 °C by adding AFT increasing minerals or species to the coal blend before it is fed into the gasification process. By increasing the AFT, the direct effect will be that steam consumption can be decreased, which in turn will improve carbon utilization. 相似文献
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