全文获取类型
收费全文 | 1156篇 |
免费 | 113篇 |
国内免费 | 98篇 |
专业分类
电工技术 | 199篇 |
综合类 | 75篇 |
化学工业 | 202篇 |
金属工艺 | 65篇 |
机械仪表 | 104篇 |
建筑科学 | 42篇 |
矿业工程 | 20篇 |
能源动力 | 44篇 |
轻工业 | 22篇 |
水利工程 | 11篇 |
石油天然气 | 137篇 |
武器工业 | 3篇 |
无线电 | 77篇 |
一般工业技术 | 61篇 |
冶金工业 | 101篇 |
原子能技术 | 3篇 |
自动化技术 | 201篇 |
出版年
2024年 | 4篇 |
2023年 | 23篇 |
2022年 | 103篇 |
2021年 | 88篇 |
2020年 | 27篇 |
2019年 | 32篇 |
2018年 | 19篇 |
2017年 | 33篇 |
2016年 | 38篇 |
2015年 | 40篇 |
2014年 | 67篇 |
2013年 | 73篇 |
2012年 | 69篇 |
2011年 | 74篇 |
2010年 | 69篇 |
2009年 | 65篇 |
2008年 | 58篇 |
2007年 | 59篇 |
2006年 | 58篇 |
2005年 | 59篇 |
2004年 | 41篇 |
2003年 | 38篇 |
2002年 | 35篇 |
2001年 | 35篇 |
2000年 | 29篇 |
1999年 | 13篇 |
1998年 | 22篇 |
1997年 | 27篇 |
1996年 | 26篇 |
1995年 | 13篇 |
1994年 | 12篇 |
1993年 | 3篇 |
1992年 | 4篇 |
1991年 | 1篇 |
1989年 | 3篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1961年 | 1篇 |
1958年 | 1篇 |
1955年 | 3篇 |
排序方式: 共有1367条查询结果,搜索用时 0 毫秒
31.
32.
Ka-Na Lin Kan Zhang Wei Zhao Shi-Ying Huang Hao Li 《International journal of molecular sciences》2022,23(3)
Insulin-like growth factor 1 (IGF-1) not only regulates neuronal function and development but also is neuroprotective in the setting of acute ischemic stroke. G-protein-coupled receptor 17 (GPR17) expression in brain tissue serves as an indicator of brain damage. As whether IGF-1 regulates GPR17 expression remains unknown, the aim of this study is to investigate how IGF-1 regulates GPR17 expression in vitro. Human neuroblastoma SK-N-SH cells were used. Lentivirus-mediated short hairpin RNA (shRNA) was constructed to mediate the silencing of FoxO1, while adenoviral vectors were used for its overexpression. Verification of the relevant signaling cascade was performed using a FoxO1 inhibitor (AS1842856), a phosphatidylinositol 3-kinase (PI3K) inhibitor (LY294002), and a GPR17 antagonist (cangrelor). Cell proliferation was analyzed using EdU staining; immunofluorescence staining was used to detect the expression and subcellular localization of FoxO1. Chromatin immunoprecipitation was used to analyze the binding of FoxO1 to the GPR17 promoter in SK-N-SH cells. The expression of FoxO1, GPR17, and protein kinase B (also known as Akt) mRNA and protein as well as the levels of FoxO1 and Akt phosphorylation were investigated in this study. IGF-1 was found to downregulate FoxO1 and GPR17 expression in SK-N-SH cells while promoting cell viability and proliferation. Inhibition of FoxO1 and antagonism of GPR17 were found to play a role similar to that of IGF-1. Silencing of FoxO1 by lentivirus-mediated shRNA resulted in the downregulation of FoxO1 and GPR17 expression. The overexpression of FoxO1 via adenoviral vectors resulted in the upregulation of FoxO1 and GPR17 expression. Blocking of PI3K signaling by LY294002 inhibited the effect of IGF-1 on GPR17 suppression. Results from chromatin immunoprecipitation revealed that IGF-1 promotes FoxO1 nuclear export and reduces FoxO1 binding to the GPR17 promoter in SK-N-SH cells. Here, we conclude that IGF-1 enhances cell viability and proliferation in SK-N-SH cells via the promotion of FoxO1 nuclear export and reduction of FoxO1 binding to the GPR17 promoter via PI3K/Akt signaling. Our findings suggest that the enhancement of IGF-1 signaling to antagonize GPR17 serves as a potential therapeutic strategy in the management of acute ischemic stroke. 相似文献
33.
通过对某 1 2 5mL摩托车用四冲程发动机的近场噪声测量和频率跟踪分析 ,得到了发动机各部位的近场噪声频谱特性 ,因而可以识别和分离发动机噪声源 ,并提出应注意的问题和改进方向。 相似文献
34.
35.
36.
Leonid Churilov Audur Fridriksdottir Mahsa Keshtkaran Ian Mosley Andrew Flitman Helen M. Dewey 《Computers & Operations Research》2013
Stroke is the third most common cause of death and the sixth most common cause of disability worldwide. Treating acute ischemic stroke with thrombolytic therapy within 4.5 hours from symptom onset is effective in improving patient outcomes. The time from stroke onset to arrival to hospital has been identified as the single most important issue in determining patients' eligibility for stroke thrombolysis. There is a need for simultaneous systemic evaluation of multi-factorial interventions in pre-hospital acute care systems, aimed at increasing patients' eligibility for stroke thrombolysis. In this paper an OR solution is proposed in the form of a simulation model that provides clear measure of the relative benefit of alternative potential interventions, demonstrating how OR modeling can be used for providing decision support in pre-hospital stroke care operations and contributing to health OR literature. 相似文献
37.
38.
中国书画的计算机虚拟绘制概述 总被引:1,自引:0,他引:1
综述了中国书画的计算机模拟绘制方法,讨论了中国书画的特点和建模、绘制方面的要求.把绘制方法分为2D,3D毛笔模型以及基于参数化曲线的纯几何图形学方法,对其中的典型算法进行了分析和比较.最后,对今后中国书画的计算机模拟绘制的研究重点进行了展望. 相似文献
39.
Yuchen Zhang Naijun Dong Huanle Hong Jingxuan Qi Shibo Zhang Jiao Wang 《International journal of molecular sciences》2022,23(5)
Due to aging of the world’s population, stroke has become increasingly prevalent, leading to a rise in socioeconomic burden. In the recent past, stroke research and treatment have become key scientific issues that need urgent solutions, with a sharp focus on stem cell transplantation, which is known to treat neurodegenerative diseases related to traumatic brain injuries, such as stroke. Indeed, stem cell therapy has brought hope to many stroke patients, both in animal and clinical trials. Mesenchymal stem cells (MSCs) are most commonly utilized in biological medical research, due to their pluripotency and universality. MSCs are often obtained from adipose tissue and bone marrow, and transplanted via intravenous injection. Therefore, this review will discuss the therapeutic mechanisms of MSCs and extracellular vehicles (EVs) secreted by MSCs for stroke, such as in attenuating inflammation through immunomodulation, releasing trophic factors to promote therapeutic effects, inducing angiogenesis, promoting neurogenesis, reducing the infarct volume, and replacing damaged cells. 相似文献
40.
Tingting Gu Jesper Just Katrine Tang Stenz Yan Yan Peter Sieljacks Jakob Wang Thomas Skjaerlund Groennebaek Jesper Emil Jakobsgaard Emil Rindom Jon Herskind Anders Gravholt Thomas Ravn Lassen Mathias Jrgensen Rikke Bk Eugenio Gutirrez-Jimnez Nina Kerting Iversen Peter Mondrup Rasmussen Jens Randel Nyengaard Malene Mller Jrgensen Frank de Paoli Hans Erik Btker Jrgen Kjems Kristian Vissing Kim Ryun Drasbek 《International journal of molecular sciences》2022,23(6)
Ischemic conditioning and exercise have been suggested for protecting against brain ischemia-reperfusion injury. However, the endogenous protective mechanisms stimulated by these interventions remain unclear. Here, in a comprehensive translational study, we investigated the protective role of extracellular vesicles (EVs) released after remote ischemic conditioning (RIC), blood flow restricted resistance exercise (BFRRE), or high-load resistance exercise (HLRE). Blood samples were collected from human participants before and at serial time points after intervention. RIC and BFRRE plasma EVs released early after stimulation improved viability of endothelial cells subjected to oxygen-glucose deprivation. Furthermore, post-RIC EVs accumulated in the ischemic area of a stroke mouse model, and a mean decrease in infarct volume was observed for post-RIC EVs, although not reaching statistical significance. Thus, circulating EVs induced by RIC and BFRRE can mediate protection, but the in vivo and translational effects of conditioned EVs require further experimental verification. 相似文献