全文获取类型
收费全文 | 9201篇 |
免费 | 938篇 |
国内免费 | 209篇 |
专业分类
电工技术 | 671篇 |
综合类 | 301篇 |
化学工业 | 1779篇 |
金属工艺 | 357篇 |
机械仪表 | 608篇 |
建筑科学 | 777篇 |
矿业工程 | 386篇 |
能源动力 | 308篇 |
轻工业 | 741篇 |
水利工程 | 137篇 |
石油天然气 | 452篇 |
武器工业 | 33篇 |
无线电 | 882篇 |
一般工业技术 | 1232篇 |
冶金工业 | 355篇 |
原子能技术 | 42篇 |
自动化技术 | 1287篇 |
出版年
2024年 | 78篇 |
2023年 | 255篇 |
2022年 | 359篇 |
2021年 | 570篇 |
2020年 | 418篇 |
2019年 | 387篇 |
2018年 | 444篇 |
2017年 | 446篇 |
2016年 | 352篇 |
2015年 | 450篇 |
2014年 | 632篇 |
2013年 | 722篇 |
2012年 | 803篇 |
2011年 | 800篇 |
2010年 | 695篇 |
2009年 | 590篇 |
2008年 | 526篇 |
2007年 | 461篇 |
2006年 | 499篇 |
2005年 | 372篇 |
2004年 | 174篇 |
2003年 | 119篇 |
2002年 | 69篇 |
2001年 | 27篇 |
2000年 | 32篇 |
1999年 | 20篇 |
1998年 | 8篇 |
1997年 | 5篇 |
1996年 | 8篇 |
1995年 | 8篇 |
1994年 | 4篇 |
1993年 | 3篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1983年 | 1篇 |
1980年 | 1篇 |
1979年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
处理传输故障的关键是故障的准确定位。为了达到这个目标,需要在维护时清楚故障定位的原则、排查故障的可能原因,掌握一种高效的手段或方法来迅速处理可能遇到的各种故障。 相似文献
102.
103.
Zhaoyue Wang Bo Yi Mandi Wu Dong Lv Ming-Liang He Meijin Liu Xi Yao 《Advanced functional materials》2021,31(34):2102888
Surface-deposited pathogens are sources for the spread of infectious diseases. Protecting public facilities with a replaceable or recyclable antifouling coating is a promising approach to control pathogen transmission. However, most antifouling coatings are less effective in preventing pathogen-contained respiratory droplets because these tiny droplets are difficult to repel, and the deposited pathogens can remain viable from hours to days. Inspired by mucus, an antimicrobial supramolecular organogel for the control of microdroplet-mediated pathogen spread is developed. The developed organogel coating harvests a couple of unique features including localized molecular control-release, readily damage healing, and persistent fouling-release properties, which are preferential for antifouling coating. Microdroplets deposited on the organogel surfaces will be spontaneously wrapped with a thin liquid layer, and will therefore be disinfected rapidly due to a mechanism of spatially enhanced release of bactericidal molecules. Furthermore, the persistent fouling-release and damage-healing properties will significantly extend the life-span of the coating, making it promising for diverse applications. 相似文献
104.
Sichen Gu Si-Wei Zhang Junwei Han Yaqian Deng Chong Luo Guangmin Zhou Yanbing He Guodan Wei Feiyu Kang Wei Lv Quan-Hong Yang 《Advanced functional materials》2021,31(28):2102128
Lithium metal anodes (LMAs) are promising for next-generation batteries but have poor compatibility with the widely used carbonate-based electrolytes, which is a major reason for their severe dendrite growth and low Coulombic efficiency (CE). A nitrate additive to the electrolyte is an effective solution, but its low solubility in carbonates is a problem that can be solved using a crown ether, as reported. A rubidium nitrate additive coordinated with 18-crown-6 crown ether stabilizes the LMA in a carbonate electrolyte. The coordination promotes the dissolution of NO3− ions and helps form a dense solid electrolyte interface that is Li3N-rich which guides uniform Li deposition. In addition, the Rb (18-crown-6)+ complexes are adsorbed on the dendrite tips, shielding them from Li deposition on the dendrite tips. A high CE of 97.1% is achieved with a capacity of 1 mAh cm−2 in a half cell, much higher than when using the additive-free electrolyte (92.2%). Such an additive is very compatible with a nickel-rich ternary cathode at a high voltage, and the assembled full battery with a cathode material loading up to 10 mg cm−2 shows an average CE of 99.8% over 200 cycles, indicating a potential for practical use. 相似文献
105.
为了推进细石混凝土泵的国产化,在保证产品性能的前提下,降低其电气系统的生产成本,采用以国产信捷PLC(Programmable Logic Controller)为主的控制元件对细石混凝土泵电气系统进行了设计。在保证细石混凝土泵使用稳定性的同时,降低了其电气系统的制造成本,提高了适用性。所设计电气系统经菏泽永安机械制造有限公司检验使用,实际应用情况良好。 相似文献
106.
Since the successful release of the IEEE 802.15.4 standard, a great convenience is offered to applications in low-power and low-rate wireless sensor networks (WSNs) which almost touch upon all aspects in our surrounding circumstances. For time-critical applications, we use a modified Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) mechanism called Linear Increase Backoff (LIB) to enhance the performance of packet delay, but not compromise the metrics of energy efficiency and throughput. An accurate and comprehensive Markov model is used to analyze the characteristics of our LIB scheme predicting packet delay, energy consumption and throughput of unsaturated, unacknowledged IEEE 802.15.4 networks in which the unsaturated state is dependent on the traffic condition rather than the depiction by a predetermined length. Simulation results are consistent with the predictions of this model. We also compare the performance of LIB with that of several mechanisms according to the optimal parameters selected from operating point, and find that packet delay is obviously superior to that of other schemes, while energy efficiency and throughput are superior to others for large number of nodes and high traffic arrivals. 相似文献
107.
108.
109.
110.
Baoliang Lv Zhenyu Liu Hong Tian Yao Xu Dong Wu Yuhan Sun 《Advanced functional materials》2010,20(22):3987-3996
Despite significant advances in iron oxide nanoparticles, it is still a challenge to synthesize regular polyhedral single‐crystalline α‐Fe2O3 particles because the surface energies of several low‐index planes are fairly similar. In the work presented here, well‐dispersed and single‐crystalline dodecahedral and octodecahedral α‐Fe2O3 particles are synthesized by a facile hydrothermal method with the aid of F? anions. The crystalline structure of the polyhedral particles is disclosed by various characterization techniques. The dodecahedral particles are of hexagonal bipyramidal shape and enclosed by twelve equivalent (101) planes. The octodecahedral particles are formed by adding six equivalent (111) planes on the two tips of a dodecahedral particle, that is, they are enclosed by twelve (101) planes and six (111) planes. The existence of F? anions plays a crucial role in the control of polyhedral particle shape. The function of F? anions in the shape formation of the polyhedral particles is proposed as follows: 1) A high concentration of exposed Fe3+ cations induces preferential adsorption of F? anions on the (100) plane and leads to the slowest growth along the [100] direction. When the concentration of F? anions is higher than 24 mM , a stable speed ratio of growth along the [001] and [100] directions results in the exposure of (101) planes. 2) With a lower concentration of F? anions, six symmetrical (111) planes with low concentration of exposed Fe3+ cations are present at the tops of a dodecahedral particle to form an octodecahedron. Furthermore, the dodecahedral and octodecahedral α‐Fe2O3 particles show much stronger magnetism than the previously reported α‐Fe2O3 nanostructures, having coercivities of 4986 Oe and 6512 Oe, respectively. Such high coercivities are attributed to a large local magnetic anisotropy, which might be induced by the polyhedron with equivalent crystallographic planes and/or the presence of F? anions. 相似文献