全文获取类型
收费全文 | 85836篇 |
免费 | 9720篇 |
国内免费 | 4566篇 |
专业分类
电工技术 | 6316篇 |
技术理论 | 1篇 |
综合类 | 6521篇 |
化学工业 | 13043篇 |
金属工艺 | 5381篇 |
机械仪表 | 6135篇 |
建筑科学 | 7013篇 |
矿业工程 | 2995篇 |
能源动力 | 2358篇 |
轻工业 | 5668篇 |
水利工程 | 1825篇 |
石油天然气 | 4451篇 |
武器工业 | 879篇 |
无线电 | 10534篇 |
一般工业技术 | 9523篇 |
冶金工业 | 3645篇 |
原子能技术 | 1079篇 |
自动化技术 | 12755篇 |
出版年
2025年 | 7篇 |
2024年 | 1130篇 |
2023年 | 1480篇 |
2022年 | 2757篇 |
2021年 | 3656篇 |
2020年 | 2849篇 |
2019年 | 2197篇 |
2018年 | 2432篇 |
2017年 | 2777篇 |
2016年 | 2584篇 |
2015年 | 3836篇 |
2014年 | 4567篇 |
2013年 | 5432篇 |
2012年 | 6131篇 |
2011年 | 6528篇 |
2010年 | 6040篇 |
2009年 | 5999篇 |
2008年 | 5728篇 |
2007年 | 5578篇 |
2006年 | 5095篇 |
2005年 | 4357篇 |
2004年 | 2924篇 |
2003年 | 2435篇 |
2002年 | 2277篇 |
2001年 | 1992篇 |
2000年 | 1689篇 |
1999年 | 1620篇 |
1998年 | 1087篇 |
1997年 | 969篇 |
1996年 | 844篇 |
1995年 | 689篇 |
1994年 | 563篇 |
1993年 | 413篇 |
1992年 | 320篇 |
1991年 | 255篇 |
1990年 | 208篇 |
1989年 | 178篇 |
1988年 | 136篇 |
1987年 | 87篇 |
1986年 | 75篇 |
1985年 | 34篇 |
1984年 | 34篇 |
1983年 | 13篇 |
1982年 | 24篇 |
1981年 | 15篇 |
1980年 | 20篇 |
1979年 | 8篇 |
1978年 | 8篇 |
1976年 | 7篇 |
1951年 | 12篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
71.
Yourong Feng Qi Chen Sien Yee Lau Bridget W. Tsai Katie Groom Carolyn J. Barrett Lawrence W. Chamley 《International journal of molecular sciences》2022,23(21)
Placental extracellular vesicles (EVs) have increasingly been recognized as a major mediator of feto-maternal communication. However, the cellular and molecular mechanisms of the uptake of placental EVs by recipient cells are still not well-understood. We previously reported that placental EVs target a limited number of organs in vivo. In the current study, we investigated the mechanisms underlying the uptake of placental EVs into target cells. Placental EVs were derived from explant cultures of normal or preeclamptic placentae. The mechanisms underlying the uptake of placental EVs were elucidated, using the phagocytosis or endocytosis inhibitor, trypsin-treatment or integrin-blocking peptides. The endothelial cell activation was studied using the monocyte adhesion assay after the preeclamptic EVs exposure, with and/or without treatment with the integrin blocking peptide, YIGSR. The cellular mechanism of the uptake of the placental EVs was time, concentration and energy-dependent and both the phagocytosis and endocytosis were involved in this process. Additionally, proteins on the surface of the placental EVs, including integrins, were involved in the EV uptake process. Furthermore, inhibiting the uptake of preeclamptic EVs with YIGSR, reduced the endothelial cell activation. The interaction between the placental EVs and the recipient cells is mediated by integrins, and the cellular uptake is mediated by a combination of both phagocytosis and endocytosis. 相似文献
72.
二氧化氯处理含氰废水处理工艺浅析 总被引:1,自引:1,他引:0
用二步氯化氧化法处理含氰废水,各种氯化氧化剂比较选择的结果表明二氧化氯具有一系列优点。通过具体工程实例介绍二氧化氯处理含氰废水工艺流程设计、工艺参数、自动控制运行参数等。 相似文献
73.
Ruizhe Huang Caiqin Gao Yongqian Shi Libi Fu Yuezhan Feng Wei Shui 《International journal of molecular sciences》2022,23(21)
As a universal polymer material, polystyrene (PS) is widely applied in electrical devices and construction. Thus, it is necessary to improve the flame retardancy and electromagnetic shielding properties of PS material. In this work, PS/silicon-wrapped ammonium polyphosphate/Inorganic acid-treated multi-walled carbon nanotubes composites (PS/SiAPP/aMWCNT, abbreviated as PAC) were prepared via methods of filtration-induced assembly and hot-pressing. Morphology and structure characterization demonstrated that SiAPP and aMWCNT had good dispersion in PS and excellent compatibility with the PS matrix. Thermogravimetric analysis revealed that the addition of aMWCNT to PS improved its thermal stability and carbon-forming characteristics. The peak heat release rate, the peak carbon monoxide production rate, and the peak smoke production rate of the PAC10 composite decreased by 53.7%, 41.9%, and 45.5%, respectively, while its electromagnetic shielding effectiveness reached 12 dB. These enhancements were attributed to the reason that SiAPP and aMWCNT synergistically catalyzed the char generation and SiAPP produced free radical scavengers and numbers of incombustible gases, which could decrease the oxygen concentration and retard the combustion reaction. Therefore, the assembled PS/SiAPP/aMWCNT system provides a new pathway to improve the flame retardant and electromagnetic shielding properties of PS. 相似文献
74.
Ling Ding Yuning Yang Qin Lu Dongfeng Qu Parthasarathy Chandrakesan Hailan Feng Hong Chen Xuzheng Chen Zhuhui Liao Jian Du Zhiyun Cao Nathaniel Weygant 《International journal of molecular sciences》2022,23(21)
Colorectal cancer (CRC) is a major source of morbidity and mortality, characterized by intratumoral heterogeneity and the presence of cancer stem cells (CSCs). Bufalin has potent activity against many tumors, but studies of its effect on CRC stemness are limited. We explored bufalin’s function and mechanism using CRC patient-derived organoids (PDOs) and cell lines. In CRC cells, bufalin prevented nuclear translocation of β-catenin and down-regulated CSC markers (CD44, CD133, LGR5), pluripotency factors, and epithelial–mesenchymal transition (EMT) markers (N-Cadherin, Slug, ZEB1). Functionally, bufalin inhibited CRC spheroid formation, aldehyde dehydrogenase activity, migration, and invasion. Network analysis identified a C-Kit/Slug signaling axis accounting for bufalin’s anti-stemness activity. Bufalin treatment significantly downregulated C-Kit, as predicted. Furthermore, overexpression of C-Kit induced Slug expression, spheroid formation, and bufalin resistance. Similarly, overexpression of Slug resulted in increased expression of C-Kit and identical functional effects, demonstrating a pro-stemness feedback loop. For further study, we established PDOs from diagnostic colonoscopy. Bufalin differentially inhibited PDO growth and proliferation, induced apoptosis, restored E-cadherin, and downregulated CSC markers CD133 and C-Myc, dependent on C-Kit/Slug. These findings suggest that the C-Kit/Slug axis plays a pivotal role in regulating CRC stemness, and reveal that targeting this axis can inhibit CRC growth and progression. 相似文献
75.
76.
通过不同的工艺路线制备了各向异性柔性黏结NdFeB磁体,并且分析了影响各向异性柔性黏结NdFeB磁体的因素。试验结果表明,通过溶解造粒和脉冲磁化以及磁场压延等工艺能够显著提高磁体的磁性能。 相似文献
77.
Feng Zhang Kumar Ganesan Yan Li Jianping Chen 《International journal of molecular sciences》2022,23(17)
Potential drug toxicities and drug interactions of redundant compounds of plant complexes may cause unexpected clinical responses or even severe adverse events. On the other hand, super-additivity of drug interactions between natural products and synthetic drugs may be utilized to gain better performance in disease management. Although without enough datasets for prediction model training, based on the SwissSimilarity and PubChem platforms, for the first time, a feasible workflow of prediction of both toxicity and drug interaction of plant complexes was built in this study. The optimal similarity score threshold for toxicity prediction of this system is 0.6171, based on an analysis of 20 different herbal medicines. From the PubChem database, 31 different sections of toxicity information such as “Acute Effects”, “NIOSH Toxicity Data”, “Interactions”, “Hepatotoxicity”, “Carcinogenicity”, “Symptoms”, and “Human Toxicity Values” sections have been retrieved, with dozens of active compounds predicted to exert potential toxicities. In Spatholobus suberectus Dunn (SSD), there are 9 out of 24 active compounds predicted to play synergistic effects on cancer management with various drugs or factors. The synergism between SSD, luteolin and docetaxel in the management of triple-negative breast cancer was proved by the combination index assay, synergy score detection assay, and xenograft model. 相似文献
78.
Dilini Singappuli-Arachchige Shuren Feng Lijun Wang Pierre E. Palo Samuel O. Shobade Michelle Thomas Marit Nilsen-Hamilton 《International journal of molecular sciences》2022,23(18)
Magnetosomes of magnetotactic bacteria consist of magnetic nanocrystals with defined morphologies enclosed in vesicles originated from cytoplasmic membrane invaginations. Although many proteins are involved in creating magnetosomes, a single magnetosome protein, Mms6 from Magnetospirillum magneticum strain AMB-1, can direct the crystallization of magnetite nanoparticles in vitro. The in vivo role of Mms6 in magnetosome formation is debated, and the observation that Mms6 binds Fe3+ more tightly than Fe2+ raises the question of how, in a magnetosome environment dominated by Fe3+, Mms6 promotes the crystallization of magnetite, which contains both Fe3+ and Fe2+. Here we show that Mms6 is a ferric reductase that reduces Fe3+ to Fe2+ using NADH and FAD as electron donor and cofactor, respectively. Reductase activity is elevated when Mms6 is integrated into either liposomes or bicelles. Analysis of Mms6 mutants suggests that the C-terminal domain binds iron and the N-terminal domain contains the catalytic site. Although Mms6 forms multimers that involve C-terminal and N-terminal domain interactions, a fusion protein with ubiquitin remains a monomer and displays reductase activity, which suggests that the catalytic site is fully in the monomer. However, the quaternary structure of Mms6 appears to alter the iron binding characteristics of the C-terminal domain. These results are consistent with a hypothesis that Mms6, a membrane protein, promotes the formation of magnetite in vivo by a mechanism that involves reducing iron. 相似文献
79.
总结了基于数据驱动的故障诊断技术理论、方法及其在航天器上的应用现状,指出其面临的挑战并提出一种解决方案。将基于数据驱动的故障诊断方法按照技术发展顺序分为基于传统机器学习的方法、基于深度学习的方法以及基于迁移学习的方法。基于传统机器学习的方法需要大量的人工参与和丰富的专家经验,在小样本数据上有着优异的性能,但不适合处理大数据。在大数据背景下,重点介绍了卷积神经网络、循环神经网络、深度自编码器以及深度信念网络的基本概念以及原理,对其在航天器故障诊断领域的研究现状进行了阐述和总结。针对深度学习严重依赖于带标签数据这一问题,介绍了基于迁移学习的故障诊断技术,并提出适应航天器应用的场景,为数据驱动的故障诊断技术工程应用提供了一种方法和思路。 相似文献
80.