全文获取类型
收费全文 | 45375篇 |
免费 | 3320篇 |
国内免费 | 1907篇 |
专业分类
电工技术 | 2593篇 |
技术理论 | 3篇 |
综合类 | 3547篇 |
化学工业 | 7283篇 |
金属工艺 | 2604篇 |
机械仪表 | 3098篇 |
建筑科学 | 3052篇 |
矿业工程 | 1072篇 |
能源动力 | 1337篇 |
轻工业 | 3981篇 |
水利工程 | 927篇 |
石油天然气 | 1729篇 |
武器工业 | 433篇 |
无线电 | 4874篇 |
一般工业技术 | 5084篇 |
冶金工业 | 2062篇 |
原子能技术 | 497篇 |
自动化技术 | 6426篇 |
出版年
2024年 | 76篇 |
2023年 | 383篇 |
2022年 | 936篇 |
2021年 | 1350篇 |
2020年 | 1055篇 |
2019年 | 893篇 |
2018年 | 1009篇 |
2017年 | 1141篇 |
2016年 | 1171篇 |
2015年 | 1706篇 |
2014年 | 2256篇 |
2013年 | 2815篇 |
2012年 | 3283篇 |
2011年 | 3587篇 |
2010年 | 3339篇 |
2009年 | 3276篇 |
2008年 | 3227篇 |
2007年 | 3043篇 |
2006年 | 2909篇 |
2005年 | 2443篇 |
2004年 | 1833篇 |
2003年 | 1413篇 |
2002年 | 1416篇 |
2001年 | 1267篇 |
2000年 | 898篇 |
1999年 | 767篇 |
1998年 | 624篇 |
1997年 | 507篇 |
1996年 | 430篇 |
1995年 | 303篇 |
1994年 | 258篇 |
1993年 | 213篇 |
1992年 | 140篇 |
1991年 | 129篇 |
1990年 | 82篇 |
1989年 | 84篇 |
1988年 | 69篇 |
1987年 | 49篇 |
1986年 | 29篇 |
1985年 | 35篇 |
1984年 | 22篇 |
1983年 | 24篇 |
1982年 | 10篇 |
1981年 | 11篇 |
1980年 | 20篇 |
1979年 | 7篇 |
1978年 | 11篇 |
1977年 | 9篇 |
1976年 | 12篇 |
1974年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 9 毫秒
991.
992.
Won‐Gwang Lim Changshin Jo Ara Cho Jongkook Hwang Seongseop Kim Jeong Woo Han Jinwoo Lee 《Advanced materials (Deerfield Beach, Fla.)》2019,31(3)
Porous architectures are important in determining the performance of lithium–sulfur batteries (LSBs). Among them, multiscale porous architecutures are highly desired to tackle the limitations of single‐sized porous architectures, and to combine the advantages of different pore scales. Although a few carbonaceous materials with multiscale porosity are employed in LSBs, their nonpolar surface properties cause the severe dissolution of lithium polysulfides (LiPSs). In this context, multiscale porous structure design of noncarbonaceous materials is highly required, but has not been exploited in LSBs yet because of the absence of a facile method to control the multiscale porous inorganic materials. Here, a hierarchically porous titanium nitride (h‐TiN) is reported as a multifunctional sulfur host, integrating the advantages of multiscale porous architectures with intrinsic surface properties of TiN to achieve high‐rate and long‐life LSBs. The macropores accommodate the high amount of sulfur, facilitate the electrolyte penetration and transportation of Li+ ions, while the mesopores effectively prevent the LiPS dissolution. TiN strongly adsorbs LiPS, mitigates the shuttle effect, and promotes the redox kinetics. Therefore, h‐TiN/S shows a reversible capacity of 557 mA h g?1 even after 1000 cycles at 5 C rate with only 0.016% of capacity decay per cycle. 相似文献
993.
994.
995.
996.
以乳清蛋白与玉米油为原料,采用高压均质技术制备水包油型(O/W)乳液。探究乳清蛋白浓度(0.45%~3.60%)、离子强度(250 mmol/L Na Cl)对乳清蛋白乳液界面特性及其物理稳定性和氧化稳定性的影响。结果表明:随着乳清蛋白浓度的增加,乳液的粒径、乳析指数、过氧化值(POV)和丙二醛生成物(TBARS)都呈现降低的趋势,而乳液的界面蛋白浓度、电位随着蛋白浓度的增加而增加。乳液中加入250 mmol/L Na Cl能够增加乳液的粒径、乳析指数、界面蛋白含量、电位值、POV和TBARS值。上述结果表明乳液界面蛋白浓度增多,乳液的物理稳定性和氧化稳定性得到增强,而乳液中加入Na Cl后能够减弱乳液的物理稳定性和氧化稳定性。 相似文献
997.
为了提升深海养殖大黄鱼玻璃态保藏工艺,寻找适宜的大分子添加剂组合配方,并提高其玻璃态转变温度(Tg),通过添加不同浓度和不同种类的添加剂,以Tg为指标,使用Box-Benhnken试验设计和响应面分析法对添加剂进行优化组合。结果表明,最优组合设计:质量分数0.2%乳酸钠,4.0%海藻糖,4.0%麦芽糊精,0.3%柠檬酸钠。该组合条件下,样品Tg实际值可提升至-53.31℃。扫描电镜结果显示,添加组内部结构紧密、表面平整、无明显空洞,而空白组有较多的空洞,组织比较松散,说明大分子添加剂与样品内组织发生交联作用,可以有效地提升其Tg。 相似文献
998.
Walid M. Daoush Byung K. Lim Dong H. Nam Soon H. Hong 《Journal of Experimental Nanoscience》2014,9(6):588-596
Carbon nanotube/silver (CNT/Ag) nanocomposites include CNT volume fraction up to 10?vol.% were prepared by chemical reduction in solution followed by spark plasma sintering. Multiwalled CNTs underwent surface modifications by acid treatments, the Fourier transform infrared spectroscopy data indicated several functional groups loaded on the CNT surface by acid functionalisation. The acid-treated CNTs were sensitised and activated. Silver was deposited on the surface of the activated CNTs by chemical reduction of alkaline silver nitrate solution at room temperature. The microstructures of the prepared CNT/Ag nanocomposite powders were investigated by high-resolution scanning electron microscopy (HRSEM), transmission electron microscopy and X-ray powder diffraction analysis. The results indicated that the produced CNT/Ag nanocomposite powders have coated type morphology. The produced CNT/Ag nanocomposite powders were sintered by spark plasma sintering. It was observed from the microstructure investigations of the sintered materials by HRSEM that the CNTs were distributed in the silver matrix with good homogeneity. The hardness and the tensile properties of the produced CNT/Ag nanocomposites were measured. By increasing the volume fraction of CNTs in the silver matrix, the hardness values increased but the elongation values of the prepared CNT/Ag nanocomposites decreased. In addition, the tensile strength was increased by increasing the CNTs volume fraction up to 7.5?vol.%, but the sample composed of 10?vol.% CNT/Ag was fractured before yielding. 相似文献
999.
用Triton X-100/正己醇/环己烷/水四元反相微乳液体系制备了纳米羟基磷灰石(HA)粉体,确定了影响制备过程的最佳pH值和煅烧温度等工艺条件.x-射线衍射仪、TEM、SEM对羟基磷灰石的颗粒进行表征和分析表明:颗粒分散均匀,呈杆状,a轴尺寸为20~40nm左右,c轴尺寸为60~80nm,此方法可以有效地控制和改变HAP的分散性和粒度大小. 相似文献
1000.
Fan Cao Qianqian Wu Wunan Li Sheng Wang Lingmei Kong Jianhua Zhang Xiaoyu Zhang Hongbo Li Weihong Hua Andrey L. Rogach Xuyong Yang 《Small (Weinheim an der Bergstrasse, Germany)》2023,19(16):2207260
Solution-processed perovskite-based light-emitting diodes (PeLEDs) are promising candidates for low-cost, large-area displays, while severe deterioration of the perovskite light-emitting layer occurs during deposition of electron transport layers from solution in an issue. Herein, core/shell ZnO/ZnS nanoparticles as a solution-processed electron transport layer in PeLED based on quasi-2D PEA2Csn−1PbnBr3n+1 (PEA = phenylethylammonium) perovskite are employed. The deposition of ZnS shell mitigates trap states on ZnO core by anchoring sulfur to oxygen vacancies, and at the same time removes residual hydroxyl groups, which helps to suppress the interfacial trap-assisted non-radiative recombination and the deprotonation reaction between the perovskite layer and ZnO. The core/shell ZnO/ZnS nanoparticles show comparably high electron mobility to pristine ZnO nanoparticles, combined with the reduced energy barrier between the electron transport layer and the perovskite layer, improving the charge injection balance in PeLEDs. As a result, the optimized PeLEDs employing core/shell ZnO/ZnS nanoparticles as a solution-processed electron transport layer exhibit high peak luminance reaching 32 400 cd m−2, external quantum efficiency of 10.3%, and 20-fold extended longevity as compared to the devices utilizing ZnO nanoparticles, which represents one of the highest overall performances for solution-processed PeLEDs. 相似文献