全文获取类型
收费全文 | 8700篇 |
免费 | 1582篇 |
国内免费 | 232篇 |
专业分类
电工技术 | 911篇 |
综合类 | 334篇 |
化学工业 | 2711篇 |
金属工艺 | 352篇 |
机械仪表 | 70篇 |
建筑科学 | 54篇 |
矿业工程 | 87篇 |
能源动力 | 980篇 |
轻工业 | 650篇 |
水利工程 | 5篇 |
石油天然气 | 141篇 |
武器工业 | 16篇 |
无线电 | 1478篇 |
一般工业技术 | 2457篇 |
冶金工业 | 187篇 |
原子能技术 | 26篇 |
自动化技术 | 55篇 |
出版年
2024年 | 73篇 |
2023年 | 799篇 |
2022年 | 261篇 |
2021年 | 571篇 |
2020年 | 665篇 |
2019年 | 601篇 |
2018年 | 527篇 |
2017年 | 527篇 |
2016年 | 459篇 |
2015年 | 368篇 |
2014年 | 422篇 |
2013年 | 376篇 |
2012年 | 425篇 |
2011年 | 614篇 |
2010年 | 421篇 |
2009年 | 384篇 |
2008年 | 353篇 |
2007年 | 490篇 |
2006年 | 356篇 |
2005年 | 330篇 |
2004年 | 297篇 |
2003年 | 220篇 |
2002年 | 212篇 |
2001年 | 122篇 |
2000年 | 114篇 |
1999年 | 125篇 |
1998年 | 79篇 |
1997年 | 70篇 |
1996年 | 61篇 |
1995年 | 34篇 |
1994年 | 37篇 |
1993年 | 16篇 |
1992年 | 17篇 |
1991年 | 11篇 |
1990年 | 7篇 |
1989年 | 11篇 |
1988年 | 9篇 |
1987年 | 8篇 |
1986年 | 4篇 |
1985年 | 1篇 |
1984年 | 14篇 |
1983年 | 5篇 |
1982年 | 2篇 |
1981年 | 2篇 |
1980年 | 3篇 |
1978年 | 1篇 |
1975年 | 1篇 |
1954年 | 1篇 |
1951年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
变化中的全球电解二氧化锰市场 总被引:2,自引:3,他引:2
在现今所有的锰化工产品中,电解二氧化锰已经成为最具重要意义的产品。文章简单介绍了电解二氧化锰的应用领域,对全球的电池和电解二氧化锰的市场进行了分析,并对世界和中国的电解二氧化锰市场走向和趋势进行了概括性总结。 相似文献
102.
利用共沉淀合成的锰镍氢氧化物前躯体,采用Si掺杂合成Li[Li0.15Mn0.575Ni0.275]1-xSixO2(0≤x≤4%)正极材料.用X射线衍射和扫描电镜对合成的粉末样品进行了表征,研究了材料的电化学性能.通过掺杂样品的晶胞参数及电化学性能研究发现:少量的Si4+掺杂可有效提高材料的循环性能;随掺杂量的增大,晶格畸变增大,半高宽变大;其中掺量x=1%的材料电化学性能最佳,4.2 V首次放电容量为146.7 mAh/g,经200次循环放电容量仍保持在135.7 mAh/g,容量保持率为92%. 相似文献
103.
本研究以纳米纤维素(CNF)为原料,经乙酰化、原位负载ZIF-67和浸渍电解液制备出一种新型ZIF-67@乙酰化纳米纤维素(ZIF-67@ACNF)锂离子电池隔膜,系统探讨了ZIF-67的粒径对隔膜结构及性能的影响。结果表明,当ZIF-67的粒径从0.46 μm(ZIF-674@ACNF隔膜)减小至0.25 μm(ZIF-678@ACNF隔膜)时,隔膜的孔隙率从74.2%减小至52.1%,离子电导率从0.75 mS/cm下降至0.22 mS/cm,界面电阻从112.5 Ω增加至1 115.7 Ω,锂离子迁移数从0.41减小至0.31,电化学稳定窗口从5.1 V减小至4.5 V。采用ZIF-674@ACNF隔膜组装电池,在室温、0.5 C的条件下进行电池充/放电测试,初始容量达到159.6 mAh/g,循环200圈后容量保持率达到90%。 相似文献
104.
Core–Shell Structure and Interaction Mechanism of γ‐MnO2 Coated Sulfur for Improved Lithium‐Sulfur Batteries 下载免费PDF全文
Lubin Ni Zhen Wu Gangjin Zhao Chunyu Sun Chuanqiang Zhou XiangXiang Gong Guowang Diao 《Small (Weinheim an der Bergstrasse, Germany)》2017,13(14)
Lithium‐sulfur batteries have attracted worldwide interest due to their high theoretical capacity of 1672 mAh g?1 and low cost. However, the practical applications are hampered by capacity decay, mainly attributed to the polysulfide shuttle. Here, the authors have fabricated a solid core–shell γ‐MnO2‐coated sulfur nanocomposite through the redox reaction between KMnO4 and MnSO4. The multifunctional MnO2 shell facilitates electron and Li+ transport as well as efficiently prevents polysulfide dissolution via physical confinement and chemical interaction. Moreover, the γ‐MnO2 crystallographic form also provides one‐dimensional (1D) tunnels for the Li+ incorporation to alleviate insoluble Li2S2/Li2S deposition at high discharge rate. More importantly, the MnO2 phase transformation to Mn3O4 occurs during the redox reaction between polysulfides and γ‐MnO2 is first thoroughly investigated. The S@γ‐MnO2 composite exhibits a good capacity retention of 82% after 300 cycles (0.5 C) and a fade rate of 0.07% per cycle over 600 cycles (1 C). The degradation mechanism can probably be elucidated that the decomposition of the surface Mn3O4 phase is the cause of polysulfide dissolution. The recent work thus sheds new light on the hitherto unknown surface interaction mechanism and the degradation mechanism of Li‐S cells. 相似文献
105.
通过溶胶-凝胶烧结法制备了LiFePO4/graphene锂离子电池复合正极材料。采用X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)、循环伏安(CV)以及各种电化学检测技术对合成材料的结构、形貌进行了表征。LiFePO4/graphene复合材料的表面上和其中的LiFePO4微小颗粒之间都有石墨烯,说明石墨烯与LiFePO4已很好地融合在一起,形成了具有三维空间结构的立体导电网络,大大地提高了复合材料的电子导电性能及减少了电荷转移电阻,从而充分发挥了活性材料的全部潜力。电化学测量表明LiFePO4/graphene的电化学性能比LiFePO4/C更好。LiFePO4/graphene具有较高的比容量和优良的大倍率性能,在0.1和5C电流充放时,LiFePO4/graphene的比容量分别为163.81和101.57 mAh/g,而LiFePO4/C仅为146.05和54.67mAh/g。LiFePO4/graphene也具有优良循环性能,0.5C循环100次,容量保持率为98.48%。 相似文献
106.
107.
108.
“Wiring” Fe‐Nx‐Embedded Porous Carbon Framework onto 1D Nanotubes for Efficient Oxygen Reduction Reaction in Alkaline and Acidic Media 下载免费PDF全文
This study presents a novel metal‐organic‐framework‐engaged synthesis route based on porous tellurium nanotubes as a sacrificial template for hierarchically porous 1D carbon nanotubes. Furthermore, an ultrathin Fe‐ion‐containing polydopamine layer has been introduced to generate highly effective FeNxC active sites into the carbon framework and to induce a high degree of graphitization. The synergistic effects between the hierarchically porous 1D carbon structure and the embedded FeNxC active sites in the carbon framework manifest in superior catalytic activity toward oxygen reduction reaction (ORR) compared to Pt/C catalyst in both alkaline and acidic media. A rechargeable zinc‐air battery assembled in a decoupled configuration with the nonprecious pCNT@Fe@GL/CNF ORR electrode and Ni‐Fe LDH/NiF oxygen evolution reaction (OER) electrode exhibits charge–discharge overpotentials similar to the counterparts of Pt/C ORR electrode and IrO2 OER electrode. 相似文献
109.
Haegyeom Kim Dong‐Hwa Seo Jae Chul Kim Shou‐Hang Bo Lei Liu Tan Shi Gerbrand Ceder 《Advanced materials (Deerfield Beach, Fla.)》2017,29(37)
Novel and low‐cost batteries are of considerable interest for application in large‐scale energy storage systems, for which the cost per cycle becomes critical. Here, this study proposes K0.5MnO2 as a potential cathode material for K‐ion batteries as an alternative to Li technology. K0.5MnO2 has a P3‐type layered structure and delivers a reversible specific capacity of ≈100 mAh g?1 with good capacity retention. In situ X‐ray diffraction analysis reveals that the material undergoes a reversible phase transition upon K extraction and insertion. In addition, first‐principles calculations indicate that this phase transition is driven by the relative phase stability of different oxygen stackings with respect to the K content. 相似文献
110.
3D Interconnected and Multiwalled Carbon@MoS2@Carbon Hollow Nanocables as Outstanding Anodes for Na‐Ion Batteries 下载免费PDF全文
Yan Wang Qunting Qu Guangchao Li Tian Gao Feng Qian Jie Shao Weijie Liu Qiang Shi Honghe Zheng 《Small (Weinheim an der Bergstrasse, Germany)》2016,12(43):6033-6041
Currently, the specific capacity and cycling performance of various MoS2/carbon‐based anode materials for Na‐ion storage are far from satisfactory due to the insufficient structural stability of the electrode, incomplete protection of MoS2 by carbon, difficult access of electrolyte to the electrode interior, as well as inactivity of the adopted carbon matrix. To address these issues, this work presents the rational design and synthesis of 3D interconnected and hollow nanocables composed of multiwalled carbon@MoS2@carbon. In this architecture, (i) the 3D nanoweb‐like structure brings about excellent mechanical property of the electrode, (ii) the ultrathin MoS2 nanosheets are sandwiched between and doubly protected by two layers of porous carbon, (iii) the hollow structure of the primary nanofibers facilitates the access of electrolyte to the electrode interior, (iv) the porous and nitrogen‐doping properties of the two carbon materials lead to synergistic Na‐storage of carbon and MoS2. As a result, this hybrid material as the anode material of Na‐ion battery exhibits fast charge‐transfer reaction, high utilization efficiency, and ultrastability. Outstanding reversible capacity (1045 mAh g?1), excellent rate behavior (817 mAh g?1 at 7000 mA g?1), and good cycling performance (747 mAh g?1 after 200 cycles at 700 mA g?1) are obtained. 相似文献