全文获取类型
收费全文 | 543篇 |
免费 | 171篇 |
国内免费 | 6篇 |
专业分类
电工技术 | 7篇 |
综合类 | 19篇 |
化学工业 | 595篇 |
金属工艺 | 3篇 |
机械仪表 | 1篇 |
矿业工程 | 4篇 |
能源动力 | 2篇 |
轻工业 | 12篇 |
石油天然气 | 1篇 |
无线电 | 35篇 |
一般工业技术 | 21篇 |
冶金工业 | 2篇 |
原子能技术 | 4篇 |
自动化技术 | 14篇 |
出版年
2023年 | 8篇 |
2022年 | 13篇 |
2021年 | 32篇 |
2020年 | 10篇 |
2019年 | 6篇 |
2018年 | 20篇 |
2017年 | 8篇 |
2016年 | 14篇 |
2015年 | 9篇 |
2014年 | 31篇 |
2013年 | 28篇 |
2012年 | 28篇 |
2011年 | 39篇 |
2010年 | 40篇 |
2009年 | 66篇 |
2008年 | 28篇 |
2007年 | 52篇 |
2006年 | 55篇 |
2005年 | 23篇 |
2004年 | 22篇 |
2003年 | 25篇 |
2002年 | 40篇 |
2001年 | 24篇 |
2000年 | 18篇 |
1999年 | 13篇 |
1998年 | 19篇 |
1997年 | 12篇 |
1996年 | 4篇 |
1995年 | 12篇 |
1994年 | 14篇 |
1993年 | 2篇 |
1992年 | 3篇 |
1990年 | 2篇 |
排序方式: 共有720条查询结果,搜索用时 15 毫秒
1.
2.
改性膨润土对天然橡胶的力学性能影响研究 总被引:3,自引:0,他引:3
本文讨论了改性膨润土对天然橡胶的力学性能的影响,并同未改性膨润土及白炭黑作了比较。用X光衍射仪和红外光谱分析了膨润土改性前后的结构变化。 相似文献
3.
Fiqri D. Khaidizar Yasumasa Bessho Yasukazu Nakahata 《International journal of molecular sciences》2021,22(7)
Aging is a phenomenon underlined by complex molecular and biochemical changes that occur over time. One of the metabolites that is gaining strong research interest is nicotinamide adenine dinucleotide, NAD+, whose cellular level has been shown to decrease with age in various tissues of model animals and humans. Administration of NAD+ precursors, nicotinamide mononucleotide (NMN) and nicotinamide riboside (NR), to supplement NAD+ production through the NAD+ salvage pathway has been demonstrated to slow down aging processes in mice. Therefore, NAD+ is a critical metabolite now understood to mitigate age-related tissue function decline and prevent age-related diseases in aging animals. In human clinical trials, administration of NAD+ precursors to the elderly is being used to address systemic age-associated physiological decline. Among NAD+ biosynthesis pathways in mammals, the NAD+ salvage pathway is the dominant pathway in most of tissues, and NAMPT is the rate limiting enzyme of this pathway. However, only a few activators of NAMPT, which are supposed to increase NAD+, have been developed so far. In this review, we will focus on the importance of NAD+ and the possible application of an activator of NAMPT to promote successive aging. 相似文献
4.
Shuzhen Liu Guoyan An Qing Cao Tong Li Xinyu Jia Lei Lei 《International journal of molecular sciences》2021,22(11)
Increasing numbers of miRNAs have been observed as oncogenes or tumor suppressors in colorectal cancer (CRC). It was recently reported that hsa-miR-106b-5p (miR-106b) promoted CRC cell migration and invasion. However, there were also studies showing contradictory results. Therefore, in the present study, we further explore the role of miR-106b and its downstream networks in the carcinogenesis of CRC. We observed that the expression of miR-106b is significantly increased in Pan-Cancer and CRC tissues compared with normal tissues from The Cancer Genome Atlas (TCGA) database. Furthermore, we used Transwell, Cell Counting Kit-8, and colony formation assays to clarify that miR-106b promotes the migratory, invasive, and proliferative abilities of CRC cells. For the first time, we systematically screened the target mRNAs and lncRNAs of miR-106b using TCGA database and the bioinformatics algorithms. Dual-luciferase reporter assay confirmed that NR2F2-AS1 and PLEKHO2 are the direct targets of miR-106b. Furthermore, NR2F2-AS1 acts as a competing endogenous RNA (ceRNA) to regulate PLEKHO2 expression by sponging miR-106b. The results of Gene set enrichment analysis (GSEA) and Western blot indicated that they play important roles in CRC progression by regulating MAPK pathway. Thus, miR-106b/NR2F2-AS1/PLEKHO2/MAPK signaling axis may suggest the potential usage in CRC treatment. 相似文献
5.
蒙脱土接枝插层改性胶乳与天然胶乳热降解动力学的研究 总被引:1,自引:0,他引:1
采用胶乳接枝插层法制备了蒙脱土接枝插层改性胶乳;采用热重分析法对天然胶乳(NRL)和蒙脱土接枝插层改性胶乳进行了等速升温热降解动力学研究。结果表明。NRL和蒙脱土接枝插层改性胶乳在氮气中的热降解过程相似。2者的热降解率(C)不受升温速率的影响;NRL和蒙脱土接枝插层改性胶乳的平衡起始降解温度相近,而后者的平衡最大降解率开始温度和终止温度均高于前者;NRL的反应级数为2.4,表观反应活化能为218kJ/mol,而蒙脱土接枝插层改性胶乳的反应级数为1.8,表观反应活化能为151.7kJ/mol。 相似文献
6.
7.
8.
9.
10.
恒粘天然橡胶理化性能的研究 总被引:2,自引:0,他引:2
用粘度稳定剂处理天然橡胶鲜胶乳和湿杂胶,研究了粘度稳定剂种类及处理方法对橡胶的P0、PRI、MV、氮含量和加速贮存硬化值(△P)等的影响。结果表明,鲜胶乳所制得的恒粘胶经加速贮存后的△P≤1个塑性值,门尼粘度值变化量(△MV)≤3个门尼值。其它性能虽有变化,但均能达到天然生胶标准的要求。自然凝固制得的恒粘胶的P0、PRI和MV相对较高,氮含量相对较低。粘度稳定剂延长了鲜胶乳的凝固时间。粘度稳定剂处理后的杂胶,△P和△MV减少,但恒粘效果不及鲜胶乳制得的恒粘胶。 相似文献