全文获取类型
收费全文 | 36106篇 |
免费 | 1434篇 |
国内免费 | 1118篇 |
专业分类
电工技术 | 1368篇 |
技术理论 | 1篇 |
综合类 | 1819篇 |
化学工业 | 6861篇 |
金属工艺 | 4190篇 |
机械仪表 | 1717篇 |
建筑科学 | 868篇 |
矿业工程 | 392篇 |
能源动力 | 1219篇 |
轻工业 | 1447篇 |
水利工程 | 109篇 |
石油天然气 | 698篇 |
武器工业 | 226篇 |
无线电 | 3886篇 |
一般工业技术 | 5576篇 |
冶金工业 | 760篇 |
原子能技术 | 620篇 |
自动化技术 | 6901篇 |
出版年
2024年 | 111篇 |
2023年 | 321篇 |
2022年 | 550篇 |
2021年 | 631篇 |
2020年 | 505篇 |
2019年 | 500篇 |
2018年 | 476篇 |
2017年 | 695篇 |
2016年 | 944篇 |
2015年 | 1193篇 |
2014年 | 1847篇 |
2013年 | 1754篇 |
2012年 | 1981篇 |
2011年 | 3486篇 |
2010年 | 2790篇 |
2009年 | 2967篇 |
2008年 | 2562篇 |
2007年 | 2661篇 |
2006年 | 2282篇 |
2005年 | 1979篇 |
2004年 | 1726篇 |
2003年 | 1725篇 |
2002年 | 1470篇 |
2001年 | 763篇 |
2000年 | 611篇 |
1999年 | 488篇 |
1998年 | 347篇 |
1997年 | 303篇 |
1996年 | 203篇 |
1995年 | 133篇 |
1994年 | 124篇 |
1993年 | 108篇 |
1992年 | 94篇 |
1991年 | 61篇 |
1990年 | 56篇 |
1989年 | 47篇 |
1988年 | 25篇 |
1987年 | 20篇 |
1986年 | 22篇 |
1985年 | 24篇 |
1984年 | 17篇 |
1983年 | 9篇 |
1982年 | 8篇 |
1981年 | 5篇 |
1980年 | 9篇 |
1979年 | 6篇 |
1977年 | 5篇 |
1959年 | 2篇 |
1957年 | 1篇 |
1951年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
101.
Lukas Babylon Fabian Schmitt Yannik Franke Tim Hubert Gunter P. Eckert 《International journal of molecular sciences》2022,23(15)
Increased amyloid beta (Aβ) levels and mitochondrial dysfunction (MD) in the human brain characterize Alzheimer disease (AD). Folic acid, magnesium and vitamin B6 are essential micro-nutrients that may provide neuroprotection. Bioenergetic parameters and amyloid precursor protein (APP) processing products were investigated in vitro in human neuroblastoma SH-SY5Y-APP695 cells, expressing neuronal APP, and in vivo, in the invertebrate Caenorhabditis elegans (CL2006 & GMC101) expressing muscular APP. Model organisms were incubated with either folic acid and magnesium-orotate (ID63) or folic acid, magnesium-orotate and vitamin B6 (ID64) in different concentrations. ID63 and ID64 reduced Aβ, soluble alpha APP (sAPPα), and lactate levels in SH-SY5Y-APP695 cells. The latter might be explained by enhanced expression of lactate dehydrogenase (LDHA). Micronutrient combinations had no effects on mitochondrial parameters in SH-SY5Y-APP695 cells. ID64 showed a significant life-prolonging effect in C. elegans CL2006. Incubation of GMC101 with ID63 significantly lowered Aβ aggregation. Both combinations significantly reduced paralysis and thus improved the phenotype in GMC101. Thus, the combinations of the tested biofactors are effective in pre-clinical models of AD by interfering with Aβ related pathways and glycolysis. 相似文献
102.
103.
Karem Arriaza Constanza Cuevas Eduardo Pena Patricia Siques Julio Brito 《International journal of molecular sciences》2022,23(13)
Hypobaric hypoxia is a condition that occurs at high altitudes (>2500 m) where the partial pressure of gases, particularly oxygen (PO2), decreases. This condition triggers several physiological and molecular responses. One of the principal responses is pulmonary vascular contraction, which seeks to optimize gas exchange under this condition, known as hypoxic pulmonary vasoconstriction (HPV); however, when this physiological response is exacerbated, it contributes to the development of high-altitude pulmonary hypertension (HAPH). Increased levels of zinc (Zn2+) and oxidative stress (known as the “ROS hypothesis”) have been demonstrated in the vasoconstriction process. Therefore, the aim of this review is to determine the relationship between molecular pathways associated with altered Zn2+ levels and oxidative stress in HPV in hypobaric hypoxic conditions. The results indicate an increased level of Zn2+, which is related to increasing mitochondrial ROS (mtROS), alterations in nitric oxide (NO), metallothionein (MT), zinc-regulated, iron-regulated transporter-like protein (ZIP), and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase-induced protein kinase C epsilon (PKCε) activation in the development of HPV. In conclusion, there is an association between elevated Zn2+ levels and oxidative stress in HPV under different models of hypoxia, which contribute to understanding the molecular mechanism involved in HPV to prevent the development of HAPH. 相似文献
104.
105.
Minami Yamauchi Toshihiro Sato Ayana Otake Masaki Kumondai Yu Sato Masafumi Kikuchi Masamitsu Maekawa Hiroaki Yamaguchi Takaaki Abe Nariyasu Mano 《International journal of molecular sciences》2022,23(15)
Patients with liver diseases not only experience the adverse effects of liver-metabolized drugs, but also the unexpected adverse effects of renally excreted drugs. Bile acids alter the expression of renal drug transporters, however, the direct effects of bile acids on drug transport remain unknown. Renal drug transporter organic anion-transporting polypeptide 4C1 (OATP4C1) was reported to be inhibited by chenodeoxycholic acid. Therefore, we predicted that the inhibition of OATP4C1-mediated transport by bile acids might be a potential mechanism for the altered pharmacokinetics of renally excreted drugs. We screened 45 types of bile acids and calculated the IC50, Ki values, and bile acid–drug interaction (BDI) indices of bile acids whose inhibitory effect on OATP4C1 was >50%. From the screening results, lithocholic acid (LCA), glycine-conjugated lithocholic acid (GLCA), and taurine-conjugated lithocholic acid (TLCA) were newly identified as inhibitors of OATP4C1. Since the BDI index of LCA was 0.278, LCA is likely to inhibit OATP4C1-mediated transport in clinical settings. Our findings suggest that dose adjustment of renally excreted drugs may be required in patients with renal failure as well as in patients with hepatic failure. We believe that our findings provide essential information for drug development and safe drug treatment in clinics. 相似文献
106.
航管设备二次雷达捕获的目标数据A模式与C模式混杂,且每次扫描、询问某一确定目标的过程中需要对目标进行多次询问,导致数据量大大增加,后端数据处理压力增大.为解决上述问题,论文提出一种目标数据处理方案,首先对接收到的A、C模式数据进行点迹合并,再对批号数据与无批号数据分流处理,通过点迹关联、滤波跟踪、航迹管理等综合处理输出目标数据.试验结果表明该设计方案可实现目标航迹快速起始,并且在目标高机动、断续、交叉等复杂情况下能连续、稳定输出数据,具有较好实用价值. 相似文献
107.
本文通过分析信管专业学生在学习"C语言"与"数据结构"过程中存在的问题,提出了将两门课程进行整合的教学模式。 相似文献
108.
结合嵌入式实时操作系统VxWorks实现某测控系统的实际应用,以其中的TCP通信为例,讨论了在VxWorks下实现C/S通信的关键技术。 相似文献
109.
110.