全文获取类型
收费全文 | 231566篇 |
免费 | 17629篇 |
国内免费 | 9124篇 |
专业分类
电工技术 | 12474篇 |
技术理论 | 24篇 |
综合类 | 14146篇 |
化学工业 | 39288篇 |
金属工艺 | 13172篇 |
机械仪表 | 14582篇 |
建筑科学 | 17685篇 |
矿业工程 | 7503篇 |
能源动力 | 6495篇 |
轻工业 | 13648篇 |
水利工程 | 3616篇 |
石油天然气 | 16622篇 |
武器工业 | 1647篇 |
无线电 | 25356篇 |
一般工业技术 | 27934篇 |
冶金工业 | 13238篇 |
原子能技术 | 2258篇 |
自动化技术 | 28631篇 |
出版年
2024年 | 998篇 |
2023年 | 3825篇 |
2022年 | 6526篇 |
2021年 | 9158篇 |
2020年 | 7133篇 |
2019年 | 6065篇 |
2018年 | 6816篇 |
2017年 | 7618篇 |
2016年 | 6827篇 |
2015年 | 8934篇 |
2014年 | 11363篇 |
2013年 | 13465篇 |
2012年 | 14399篇 |
2011年 | 15711篇 |
2010年 | 13608篇 |
2009年 | 12883篇 |
2008年 | 12518篇 |
2007年 | 12031篇 |
2006年 | 12486篇 |
2005年 | 10882篇 |
2004年 | 7350篇 |
2003年 | 6306篇 |
2002年 | 5531篇 |
2001年 | 4928篇 |
2000年 | 5469篇 |
1999年 | 6473篇 |
1998年 | 5461篇 |
1997年 | 4480篇 |
1996年 | 4201篇 |
1995年 | 3511篇 |
1994年 | 2819篇 |
1993年 | 1976篇 |
1992年 | 1541篇 |
1991年 | 1229篇 |
1990年 | 942篇 |
1989年 | 746篇 |
1988年 | 540篇 |
1987年 | 339篇 |
1986年 | 281篇 |
1985年 | 200篇 |
1984年 | 141篇 |
1983年 | 115篇 |
1982年 | 128篇 |
1981年 | 100篇 |
1980年 | 72篇 |
1979年 | 38篇 |
1978年 | 26篇 |
1977年 | 21篇 |
1976年 | 35篇 |
1973年 | 14篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
Dr. Xicheng Liu Mingxiao Shao Congcong Liang Jinghang Guo Guangxuan Wang Xiang-Ai Yuan Zhihong Jing Laijin Tian Prof. Dr. Zhe Liu 《Chembiochem : a European journal of chemical biology》2021,22(3):557-564
A series of half-sandwich structural iridium(III) phenanthroline (Phen) complexes with halide ions (Cl−, Br−, I−) and pyridine leaving groups ([(η5-CpX)Ir(Phen)Z](PF6)n, Cpx: electron-rich cyclopentadienyl group, Z: leaving group) have been prepared. Target complexes, especially the Cpxbiph (biphenyl-substituted cyclopentadienyl)-based one, showed favourable anticancer activity against human lung cancer (A549) cells; the best one ( Ir8 ) was almost five times that of cisplatin under the same conditions. Compared with complexes involving halide ion leaving groups, the pyridine-based one did not display hydrolysis but effectively caused lysosomal damage, leading to accumulation in the cytosol, inducing an increase in the level of intracellular reactive oxygen species and apoptosis; this indicated an anticancer mechanism of oxidation. Additionally, these complexes could bind to serum albumin through a static quenching mechanism. The data highlight the potential value of half-sandwich iridium(III) phenanthroline complexes as anticancer drugs. 相似文献
992.
Weiyan He Xia Guo Xiaobing Zhao Jinrong Liu 《International Journal of Applied Ceramic Technology》2021,18(3):880-888
Nanopowders of pure zirconia have been synthesized using citric acid (CA)-assisted lamellar liquid crystal template method. The microstructure of the zirconia powder prepared at the different mole ratios of CA to zirconium oxynitrate (ZN) was characterized by FT-IR, X-ray diffraction (XRD), laser particle size analyzer, Raman spectroscopy, and scanning electron microscope (SEM) methods. The phase structure of the sodium dodecyl sulfate (SDS)/C10H21OH/H2O system before and after adding mixing solution CA and ZN was determined by POM (Polarizing Optical Microscope). The results show that lamellar structure of the SDS/C10H21OH/H2O system after adding mixing solution CA and ZN is stable. The presence of CA inhibits agglomeration and growth of zirconia particle. The crystallite size of zirconia powders decreases and agglomerates lowly with addition of CA. Fourier transform infrared spectrometry (FI-IR) analyses reveal that the structure of chelating organic complex is maintained in zirconia structure at high-temperature calcination to cause oxygen vacancies which stabilizes the tetragonal phase of zirconia. The zirconia powders remained the single metastable tetragonal phase at the molar ratios of CA to ZN ranging from 1:3 to 5:1. The crystallite size of zirconia with spherical morphology varied from 32.2 to 20.1 nm with the increase of the molar ratio of CA to ZN in the range of 1:3 to 5:1. 相似文献
993.
Wenlong Zheng Xiao Chen Chunyang Liu Shiping Ren Li Zhang 《International Journal of Applied Ceramic Technology》2021,18(4):1244-1254
Silica-based ceramic cores are extensively used in investment casting process, during which they must exhibit sufficient flexural strength and deformation resistance. In this study, micro-sized mullite was used as an additive to silica-based ceramic cores to optimize their high temperature properties. To investigate the effects of micro-sized mullite on cristobalite crystallization, mechanical and thermal properties of silica-based ceramic cores, ceramic cores with different amounts of micro-sized mullite were fabricated. The XRD results showed that additional micro-sized mullite diminished the crystallization of cristobalite at high temperatures, primarily caused by the mullite related compressive stresses on the surface regions of fused silica particles. Three-point bending tests and SEM results showed that micro-sized mullite had a more significant effect on the flexural strength of ceramic cores compared with conventional additives. Particularly, the fracture mechanism of silica-based ceramic cores had been changed from intergranular fracture into a mixed fracture consisting of both intergranular and transgranular fracture. The mechanical and thermal properties of ceramic cores were all reduced slightly as the mullite content exceed 4.6 wt%. Hence, to optimize the properties of silica-based ceramic cores, the micro-sized mullite content should not exceed 4.6 wt%. 相似文献
994.
Yin Ruitong Zhang Shaoshuai Xu Yueyang Xue Jianming Bi Jiaqian Liu Ruijiang 《Journal of Inorganic and Organometallic Polymers and Materials》2021,31(8):3584-3594
Journal of Inorganic and Organometallic Polymers and Materials - Magnetic CoxCu(1–x)Fe2O4 nanoparticles were prepared via an alcohol solution of nitrate combustion and calcination process.... 相似文献
995.
Sajjad Muhammad Asif Sana Ullah Guan Linlin Jiao Yangjing Jiang Yuhan Zhang Linlin Wen Jia Zhang Shuyu Lin Yuting Zhang Shuangshuang Ding Zhiwei Ren Yang Zhou Xiaowei Hu Wanbiao Liu Zhu 《Journal of Inorganic and Organometallic Polymers and Materials》2021,31(11):4440-4441
Journal of Inorganic and Organometallic Polymers and Materials - The original version of this article unfortunately contained mistakes. In line 9 of the abstract, 5% should read as 2%. The... 相似文献
996.
国家自然科学基金对学科发展具有扶持、引导作用, 其资助情况能反映出学科发展态势、研究前沿和热点。以2010—2019年国家自然科学基金对盐湖研究的资助项目数据为分析对象, 利用EXCEL、R Studio、VOSviewer等软件对资助年度、资助金额、依托单位、资助类别、项目名称、关键词等内容进行统计分析, 揭示了国家自然科学基金对盐湖基础研究的资助力度、趋势、研究团队分布, 发现当前盐湖热点研究方向包括盐湖相化学与溶液化学、盐湖资源分离与利用技术、盐湖资源综合利用技术、盐湖成盐规律与机制、盐湖锂资源利用技术、盐湖化学性质研究。 相似文献
997.
998.
999.