全文获取类型
收费全文 | 22346篇 |
免费 | 2029篇 |
国内免费 | 1097篇 |
专业分类
电工技术 | 1161篇 |
综合类 | 1244篇 |
化学工业 | 7061篇 |
金属工艺 | 1623篇 |
机械仪表 | 834篇 |
建筑科学 | 626篇 |
矿业工程 | 533篇 |
能源动力 | 2315篇 |
轻工业 | 2293篇 |
水利工程 | 128篇 |
石油天然气 | 929篇 |
武器工业 | 573篇 |
无线电 | 1230篇 |
一般工业技术 | 2770篇 |
冶金工业 | 1231篇 |
原子能技术 | 226篇 |
自动化技术 | 695篇 |
出版年
2024年 | 106篇 |
2023年 | 498篇 |
2022年 | 592篇 |
2021年 | 808篇 |
2020年 | 806篇 |
2019年 | 763篇 |
2018年 | 692篇 |
2017年 | 847篇 |
2016年 | 813篇 |
2015年 | 717篇 |
2014年 | 1135篇 |
2013年 | 1179篇 |
2012年 | 1345篇 |
2011年 | 1583篇 |
2010年 | 1260篇 |
2009年 | 1180篇 |
2008年 | 1086篇 |
2007年 | 1406篇 |
2006年 | 1312篇 |
2005年 | 1123篇 |
2004年 | 1071篇 |
2003年 | 878篇 |
2002年 | 824篇 |
2001年 | 644篇 |
2000年 | 582篇 |
1999年 | 435篇 |
1998年 | 334篇 |
1997年 | 285篇 |
1996年 | 209篇 |
1995年 | 188篇 |
1994年 | 170篇 |
1993年 | 105篇 |
1992年 | 117篇 |
1991年 | 84篇 |
1990年 | 63篇 |
1989年 | 47篇 |
1988年 | 50篇 |
1987年 | 27篇 |
1986年 | 16篇 |
1985年 | 21篇 |
1984年 | 20篇 |
1983年 | 9篇 |
1982年 | 14篇 |
1981年 | 4篇 |
1980年 | 7篇 |
1979年 | 7篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1973年 | 1篇 |
1951年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
Different operating regimes are considered for operation of an amperometric diffusion solid-state electrolyte cell for measuring
the volume fraction of oxygen. The design of an oxygen sensor is described. Experimental results confirm the efficiency of
the proposed diffusion solid-state electrolyte cell for measuring oxygen in the range of 98–100%.
Translated from Izmeritel’naya Tekhnika, No. 10, pp. 64–65, October, 2008. 相似文献
62.
通过室温固相法制备了不同元素掺杂的前驱体,并采用分步煅烧法获得了尖晶石型LiMn2O4和LiM0.2Mn1.8O4(M=Mg、Cd)相。采用XRD和FTIR技术就元素掺杂对产物晶格畸变、Mn—O键长和键能强度等微观结构参数和光谱频移现象进行分析。结果表明,不同元素掺杂导致产物产生不同程度的晶格畸变。Mg元素掺杂使晶格收缩,Mn(Ⅳ)—O和Mn(Ⅲ)—O键收缩和键能强度增加,对应吸收峰发生蓝移;Cd元素掺杂使晶格膨胀,Mn(Ⅳ)—O和Mn(Ⅲ)—O键增长和键能强度降低,对应吸收峰发生红移。 相似文献
63.
Runnan Yu Huifeng Yao Zhenyu Chen Jingmin Xin Ling Hong Ye Xu Yunfei Zu Wei Ma Jianhui Hou 《Advanced materials (Deerfield Beach, Fla.)》2019,31(18)
Fine‐tuning of the nanoscale morphologies of the active layers in polymer solar cells (PSCs) through various techniques plays a vital role in improving the photovoltaic performance. However, for emerging nonfullerene (NF) PSCs, the morphology optimization of the active‐layer films empirically follows the methods originally developed in fullerene‐based blends and lacks systematic studies. In this work, two solid additives with different volatilities, SA‐4 and SA‐7, are applied to investigate their influence on the morphologies and photovoltaic performances of NF‐PSCs. Although both solid additives effectively promote the molecular packing of the NF acceptors, due to the higher volatility of SA‐4, the devices processed with SA‐4 exhibit a power conversion efficiency of 13.5%, higher than that of the control devices, and the devices processed with SA‐7 exhibit poor performances. Through a series of detailed morphological analyses, it is found that the volatilization of SA‐4 after thermal annealing is beneficial for the self‐assembly packing of acceptors, while the residuals due to the incomplete volatilization of SA‐7 have a negative effect on the film morphology. The results delineate the feasibility of applying volatilizable solid additives and provide deeper insights into the working mechanism, establishing guidelines for further material design of solid additives. 相似文献
64.
65.
以过氧化苯甲酰(BPO)作引发剂,通过溶液接枝聚合法把苯乙烯/丙烯酸同时接枝到原硅酸钠改性的聚偏氟乙烯(PVDF)膜上,磺化后得到聚偏氟乙烯接枝苯乙烯/丙烯酸磺酸(PVDF-g-PS/ PASA)膜.FTIR分析表明:苯乙烯和丙烯酸接枝到PVDF膜上;环境的相对湿度在20%~80%范围内,对PVDF-g-PS/ PASA膜电导率的影响基本不变,并达到0.0198S·cm-1,40℃保水率达99%.将膜应用于CO传感器中,传感器电流响应信号与CO气体浓度具有较好的线性关系. 相似文献
66.
针对漳村煤矿综采工作面上隅角瓦斯浓度高的情况,用抽出式风机处理上隅角瓦斯,较好地解决了上隅角瓦斯频繁超限事故,实现了矿井的安全生产。 相似文献
67.
M. S. RAFIQUE M. KHALEEQ-UR-RAHMAN Shakoor MUNAZZA K. A. BHATTI 《等离子体科学和技术》2008,10(4):450-454
In this work, study of laser-induced ions is presented. The plasma was produced by focusing a Nd:YAG laser, with a wavelength of 1064 nm, a pulsed width of 9-14 ns, a power of 1.1 MW and energy of 10 mJ, on silver target in vacuum (10-3 Torr= 1.3332 Pa). The characteristics of ion streams were investigated by CR-39 detectors located at angles of 0°, 30°, 60° and 90° with respect to normal of the target. The distance between the silver target and each detector was 11 cm. The energy of silver ions was found ranging from 1.5 eV to 1.06E4 eV. There was a high concentration of ions with low energy as compared to those with high energy, showing the energy distribution amongst the ions. The flux of ions was maximum in the axial direction which was decreasing with the angle increase with respect to normal of the target, and finally became minimum in the radial direction. Hence the silver ions have shown anisotropic behaviour. 相似文献
68.
在PVC低发泡实心板挤出成型中,控制聚合物熔体的流动和发泡是保证产品质量的关键,重点介绍了生产工艺和原理,并分析了生产中的技术要点,提出了解决的办法。 相似文献
69.
70.
Yan-Ruide Li Yang Zhou Matthew Wilson Adam Kramer Ryan Hon Yichen Zhu Ying Fang Lili Yang 《International journal of molecular sciences》2022,23(14)
Invariant natural killer T (iNKT) cells have the capacity to mount potent anti-tumor reactivity and have therefore become a focus in the development of cell-based immunotherapy. iNKT cells attack tumor cells using multiple mechanisms with a high efficacy; however, their clinical application has been limited because of their low numbers in cancer patients and difficulties in infiltrating solid tumors. In this study, we aimed to overcome these critical limitations by using α-GalCer, a synthetic glycolipid ligand specifically activating iNKT cells, to recruit iNKT to solid tumors. By adoptively transferring human iNKT cells into tumor-bearing humanized NSG mice and administering a single dose of tumor-localized α-GalCer, we demonstrated the rapid recruitment of human iNKT cells into solid tumors in as little as one day and a significantly enhanced tumor killing ability. Using firefly luciferase-labeled iNKT cells, we monitored the tissue biodistribution and pharmacokinetics/pharmacodynamics (PK/PD) of human iNKT cells in tumor-bearing NSG mice. Collectively, these preclinical studies demonstrate the promise of an αGC-driven iNKT cell-based immunotherapy to target solid tumors with higher efficacy and precision. 相似文献