全文获取类型
收费全文 | 3323篇 |
免费 | 339篇 |
国内免费 | 194篇 |
专业分类
电工技术 | 199篇 |
综合类 | 204篇 |
化学工业 | 484篇 |
金属工艺 | 267篇 |
机械仪表 | 161篇 |
建筑科学 | 312篇 |
矿业工程 | 95篇 |
能源动力 | 88篇 |
轻工业 | 289篇 |
水利工程 | 56篇 |
石油天然气 | 204篇 |
武器工业 | 17篇 |
无线电 | 341篇 |
一般工业技术 | 453篇 |
冶金工业 | 227篇 |
原子能技术 | 32篇 |
自动化技术 | 427篇 |
出版年
2024年 | 14篇 |
2023年 | 66篇 |
2022年 | 93篇 |
2021年 | 148篇 |
2020年 | 92篇 |
2019年 | 100篇 |
2018年 | 108篇 |
2017年 | 146篇 |
2016年 | 104篇 |
2015年 | 120篇 |
2014年 | 165篇 |
2013年 | 220篇 |
2012年 | 220篇 |
2011年 | 239篇 |
2010年 | 188篇 |
2009年 | 181篇 |
2008年 | 155篇 |
2007年 | 162篇 |
2006年 | 174篇 |
2005年 | 146篇 |
2004年 | 97篇 |
2003年 | 105篇 |
2002年 | 134篇 |
2001年 | 99篇 |
2000年 | 91篇 |
1999年 | 78篇 |
1998年 | 76篇 |
1997年 | 68篇 |
1996年 | 54篇 |
1995年 | 50篇 |
1994年 | 37篇 |
1993年 | 36篇 |
1992年 | 24篇 |
1991年 | 11篇 |
1990年 | 14篇 |
1989年 | 9篇 |
1988年 | 8篇 |
1987年 | 4篇 |
1986年 | 7篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1977年 | 1篇 |
1976年 | 2篇 |
1975年 | 1篇 |
1973年 | 1篇 |
1943年 | 2篇 |
1935年 | 1篇 |
1934年 | 1篇 |
排序方式: 共有3856条查询结果,搜索用时 15 毫秒
1.
Wenshu Chen Jiajun Gu Yongping Du Fang Song Fanxing Bu Jinghan Li Yang Yuan Ruichun Luo Qinglei Liu Di Zhang 《Advanced functional materials》2020,30(25)
Large‐scale production of hydrogen from water‐alkali electrolyzers is impeded by the sluggish kinetics of hydrogen evolution reaction (HER) electrocatalysts. The hybridization of an acid‐active HER catalyst with a cocatalyst at the nanoscale helps boost HER kinetics in alkaline media. Here, it is demonstrated that 1T–MoS2 nanosheet edges (instead of basal planes) decorated by metal hydroxides form highly active / heterostructures, which significantly enhance HER performance in alkaline media. Featured with rich / sites, the fabricated 1T–MoS2 QS/Ni(OH)2 hybrid (quantum sized 1T–MoS2 sheets decorated with Ni(OH)2 via interface engineering) only requires overpotentials of 57 and 112 mV to drive HER current densities of 10 and 100 mA cm?2, respectively, and has a low Tafel slope of 30 mV dec?1 in 1 m KOH. So far, this is the best performance for MoS2‐based electrocatalysts and the 1T–MoS2 QS/Ni(OH)2 hybrid is among the best‐performing non‐Pt alkaline HER electrocatalysts known. The HER process is durable for 100 h at current densities up to 500 mA cm?2. This work not only provides an active, cost‐effective, and robust alkaline HER electrocatalyst, but also demonstrates a design strategy for preparing high‐performance catalysts based on edge‐rich 2D quantum sheets for other catalytic reactions. 相似文献
2.
3.
Weigang Liang Beibei Wang Guofeng Shen Suzhen Cao Bertrand Mcswain Ning Qin Liyun Zhao Dongmei Yu Jicheng Gong Shanshan Zhao Yawei Zhang Xiaoli Duan 《Indoor air》2020,30(2):264-274
Stunting adversely affects physical and mental outcomes of children. It has not been examined whether household air pollution from solid fuel combustion is a risk factor for stunting in children. In a total of 41,439 children aged 6-17 across China, height was measured using a unified protocol. Multivariable linear regression models and logistic regression models were used to assess the associations of solid fuel use for cooking/heating with stunting in children. Adjusted for covariates, cooking/heating with solid fuel was significantly associated with a lower z-score for height for age and sex (β = −0.21 [−0.32 to −0.09] and −0.17 [−0.31 to −0.03], respectively) and an increased risk of stunting with an estimated ORs of 1.34 [1.07~1.68] and 1.37 [1.02~1.83], respectively. The risk of stunting associated with solid fuel use was statistically significant in high-age children. And the effect was greater on girls than on boys, though the difference was not statistically significant. Our study suggested that Chinese children living in households using solid fuel had a significantly higher risk of stunting than those living in households using cleaner fuel. 相似文献
4.
5.
6.
7.
火焰喷涂是激光熔覆前合金粉末的预置方法之一。本文在实验的基础上,探讨了工艺过程,并讨论了影响质量的因素。 相似文献
8.
9.
辽河油田石化总厂为提高从辽河原油生产重交通道路沥青的质量,对所用的辽河原油中的低凝点环烷基原油经过分储、分输、分炼,对减压蒸馏塔进行改造,控制减压拔出率,对直馏沥青进行轻度氧化,使90号重交通道路沥青中沥青质的含量大于10%,蜡含量小于2%,质量达到了国际先进水平。 相似文献
10.
A Nu?ez C De la Roza ML Rodrigo-Angulo W Bu?o F Reinoso-Suárez 《Canadian Metallurgical Quarterly》1997,754(1-2):1-11
This study analyses the relationship between the use of rotating instruments, the production of a smear layer and the presence of alterations to enamel microstructures. The rotating instruments used were carbide (8-12 blade) and diamond tipped (30-15 m) cutters. Cavities were made in extracted teeth. Subsequently, half the sample was analysed using the rugosimeter before and after the application of ortophosphoric acid at 35% for 15 and the other half suing a Scansion Electronic microscope (SEM). The results obtained showed on the one hand that carbide cutters leave a smoother surfacer than diamond tipped cutters, and on the other that the smear layer is eliminated better by carbide cutters compared to diamond tipped cutters. Moreover, there are no major traumatic-type alterations at the level of the enamel affecting the microstructure after the use of carbide cutters. 相似文献