全文获取类型
收费全文 | 23338篇 |
免费 | 2692篇 |
国内免费 | 687篇 |
专业分类
电工技术 | 576篇 |
技术理论 | 1篇 |
综合类 | 1437篇 |
化学工业 | 3408篇 |
金属工艺 | 3661篇 |
机械仪表 | 588篇 |
建筑科学 | 931篇 |
矿业工程 | 5504篇 |
能源动力 | 474篇 |
轻工业 | 652篇 |
水利工程 | 105篇 |
石油天然气 | 292篇 |
武器工业 | 47篇 |
无线电 | 290篇 |
一般工业技术 | 1453篇 |
冶金工业 | 6945篇 |
原子能技术 | 147篇 |
自动化技术 | 206篇 |
出版年
2024年 | 31篇 |
2023年 | 253篇 |
2022年 | 561篇 |
2021年 | 742篇 |
2020年 | 785篇 |
2019年 | 654篇 |
2018年 | 585篇 |
2017年 | 683篇 |
2016年 | 960篇 |
2015年 | 856篇 |
2014年 | 1406篇 |
2013年 | 1407篇 |
2012年 | 1641篇 |
2011年 | 1740篇 |
2010年 | 1247篇 |
2009年 | 1139篇 |
2008年 | 898篇 |
2007年 | 1304篇 |
2006年 | 1215篇 |
2005年 | 1058篇 |
2004年 | 982篇 |
2003年 | 920篇 |
2002年 | 843篇 |
2001年 | 754篇 |
2000年 | 676篇 |
1999年 | 556篇 |
1998年 | 455篇 |
1997年 | 409篇 |
1996年 | 372篇 |
1995年 | 358篇 |
1994年 | 270篇 |
1993年 | 191篇 |
1992年 | 186篇 |
1991年 | 116篇 |
1990年 | 119篇 |
1989年 | 105篇 |
1988年 | 76篇 |
1987年 | 42篇 |
1986年 | 25篇 |
1985年 | 20篇 |
1984年 | 20篇 |
1983年 | 5篇 |
1982年 | 17篇 |
1981年 | 14篇 |
1980年 | 5篇 |
1978年 | 3篇 |
1977年 | 3篇 |
1976年 | 2篇 |
1974年 | 3篇 |
1951年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
《Advanced Powder Technology》2022,33(11):103833
Eliminating the gold preg-robbing effect of carbonaceous matter in carbonaceous gold ores is crucial for gold leaching. In this study, suspension oxidation roasting was proposed to accelerate the decarbonization of carbonaceous gold ore. The characteristics of oxidation reaction process and gas release were analyzed by TG-DTA-FTIR. The phase transformation and microstructure evolution of samples during roasting were analyzed by XRD, SEM and BET. The results show that the gold preg-robbing effect was eliminated after the gasification of carbonaceous matter, and the CaO generated by decomposition of carbonates can effectively capture the SO2. After roasting for 75 min at 650 °C in a 20% O2 atmosphere, the total carbon removal rate reached 99.42%, the distribution of exposed gold increased from 28.85% to 77.10% and the gold leaching efficiency increased from 4.55% to 84.83%. In addition, about 70% sulfur was mainly fixed in the roasted products in the form of sulfate. Therefore, the suspension oxidation roasting process is an efficient and clean pretreatment method for carbonaceous gold ores. 相似文献
2.
3.
《Ceramics International》2022,48(8):10506-10515
The search for materials and methods capable of reducing human impacts on the environment is of utmost importance nowadays. This study's primary purpose was to analyze the technical feasibility of ceramic composites production utilizing Fundão Dam's Iron Ore Tailings (IOT), Blast Furnace Slag (BFS) from charcoal, and Foundry Sand (FS) as partial substitutes for the traditional raw materials – sand and clay – for application in building industry materials. The composites were molded in rectangular specimens and fired at temperatures of 900, 950, 1000, 1050, and 1200 °C. The developed materials were analyzed and characterized by X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), Thermogravimetry (TGA), and Differential Thermal Analysis (DTA). The obtained materials had flexural strength modulus of up to 12.19 MPa, water absorption ranging from 2 to 22%, linear shrinkage ranging from 0.02 to 6.50%, and apparent density ranging from 2.03 to 1.63 g/cm3. The study of the internal structure formation process revealed the formation of amorphous structures in the composites. The results demonstrated that these waste materials may be jointly used in construction materials, contributing to the reduction of natural resource extraction, besides enabling their correct disposal, minimizing environmental impacts, and improving the life quality of the surrounding communities. 相似文献
4.
《International Journal of Hydrogen Energy》2022,47(69):29925-29944
Lithium iron phosphate battery (LIPB) is the key equipment of battery energy storage system (BESS), which plays a major role in promoting the economic and stable operation of microgrid. Based on the advancement of LIPB technology and efficient consumption of renewable energy, two power supply planning strategies and the china certified emission reduction (CCER) model are proposed respectively. Based on it, the multi-objective planning optimization model with economic benefits, environmental benefits and power supply stability as the objective function is established for the first time, and the Newton Weighted Sum Frisch method (NWSFA) solution model is adopted. In the planning process, rain flow counting method is used to research the life of BESS, which improves the accuracy of energy storage annual cost calculation. A park in northern China is taken as a case study to demonstrate the application of this model. The simulation results show that the annual economic operating cost of BESS is decreased by 18.81%, the energy supply reliability is increased by 0.15%, and the optimal electricity price adjustment ratio of the system is 15%. 相似文献
5.
Jacky Lu Kathryn P. Haley Jamisha D. Francis Miriam A. Guevara Ryan S. Doster Kelly M. Craft Rebecca E. Moore Schuyler A. Chambers Alberto G. Delgado Maria Blanca Piazuelo Steven M. Damo Dr. Steven D. Townsend Dr. Jennifer A. Gaddy 《Chembiochem : a European journal of chemical biology》2021,22(18):2783-2790
Chronic infection with Helicobacter pylori increases risk of gastric diseases including gastric cancer. Despite development of a robust immune response, H. pylori persists in the gastric niche. Progression of gastric inflammation to serious disease outcomes is associated with infection with H. pylori strains which encode the cag Type IV Secretion System (cag T4SS). The cag T4SS is responsible for translocating the oncogenic protein CagA into host cells and inducing pro-inflammatory and carcinogenic signaling cascades. Our previous work demonstrated that nutrient iron modulates the activity of the T4SS and biogenesis of T4SS pili. In response to H. pylori infection, the host produces a variety of antimicrobial molecules, including the iron-binding glycoprotein, lactoferrin. Our work shows that apo-lactoferrin exerts antimicrobial activity against H. pylori under iron-limited conditions, while holo-lactoferrin enhances bacterial growth. Culturing H. pylori in the presence of holo-lactoferrin prior to co-culture with gastric epithelial cells, results in repression of the cag T4SS activity. Concomitantly, a decrease in biogenesis of cag T4SS pili at the host-pathogen interface was observed under these culture conditions by high-resolution electron microscopy analyses. Taken together, these results indicate that acquisition of alternate sources of nutrient iron plays a role in regulating the pro-inflammatory activity of a bacterial secretion system and present novel therapeutic targets for the treatment of H. pylori-related disease. 相似文献
6.
《Ceramics International》2022,48(9):12014-12027
The formed deposits wear out of refractory wall linings in the rotary kiln and may cause production disturbances. This study describes the chemical composition and mineralogical phase components at the deposit/refractory interface in the rotary kiln for fluxed iron ore pellets production. The main phases of refractory bricks are corundum and mullite, while the deposits mainly contain hematite and silicates. The main phases in the deposit/refractory brick contact zone are hematite, anorthite (CaAl2Si2O8), mullite, corundum, and silicates. Moreover, the hematite phases in the deposit/brick interface averagely contain 6.98 wt% Al and 1.38 wt% Ti. The silicates in the contact zone contain higher aluminium content and lower iron content than the silicates in the deposits. Finally, the thermodynamic analysis indicates that the main phases in the deposits can react with the refractory to form Al2Fe2O6, CaAl2Si2O8, feldspar, and liquid phases lead to the degradation of bricks in the kiln during the iron ore pellets production. 相似文献
7.
对金品位为1.55 g/t的氧化矿采用非氰药剂进行浸金的工艺流程,考察了磨矿细度、药剂DZC浓度和浸出时间对金浸出率的影响。确定该金矿适宜的非氰浸出条件:磨矿细度-74μm含量占69.90%、石灰用量4 000g/t、矿浆液固比为2∶1、浸出药剂DZC浓度0.08%、浸出时间8 h,可获得金的浸出率为93.33%的良好指标。表明该氧化金矿在常温常压下,采用非氰浸出工艺是可行的。 相似文献
8.
9.
铁山头铜矿床处于铜陵矿集区的中东部,属于扬子陆块下扬子凹陷中的铜陵隆起。矿床位于凤凰山矿田北侧,成矿潜力较大。综合研究分析认为:①接触交代作用使得岩体接触带及附近变质形成矽卡岩矿化带;②区内凤凰山岩体(花岗闪长岩)系成矿母岩;③矿体主要赋存于花岗闪长岩与三叠系下统南陵湖组石灰岩接触带上;④矿床成因类型为高—中温热液交代矽卡岩型矿床。 相似文献
10.
以球形氰乙基木质素为原料通过液相还原法制备球形木质素负载纳米零价铁材料(LSAC-Fe),用于去除饮用水中微量的溴酸盐。采用场发射扫描电子显微镜(FESEM)、X射线衍射仪(XRD)、X射线光电子能谱仪(XPS)、氮气吸附法(BET)等对其结构进行表征,并探究了不同条件下LSAC-Fe对BrO-3的吸附效果及其热力学吸附和去除机理。研究表明,纳米零价铁可较为均匀地负载在球形木质素上,并且LSAC-Fe具有很高的表面活性;BrO-3的去除率随着初始溶液pH值的升高而降低,随着BrO-3初始溶液质量浓度的增加而降低;LSAC-Fe对BrO-3的吸附过程为吸热过程,升温可促进LSAC-Fe对BrO-3的吸附。 相似文献