全文获取类型
收费全文 | 50268篇 |
免费 | 4350篇 |
国内免费 | 2062篇 |
专业分类
电工技术 | 852篇 |
技术理论 | 1篇 |
综合类 | 3341篇 |
化学工业 | 12026篇 |
金属工艺 | 1503篇 |
机械仪表 | 2572篇 |
建筑科学 | 3244篇 |
矿业工程 | 4509篇 |
能源动力 | 1703篇 |
轻工业 | 3978篇 |
水利工程 | 642篇 |
石油天然气 | 12230篇 |
武器工业 | 483篇 |
无线电 | 987篇 |
一般工业技术 | 3221篇 |
冶金工业 | 1334篇 |
原子能技术 | 453篇 |
自动化技术 | 3601篇 |
出版年
2024年 | 764篇 |
2023年 | 744篇 |
2022年 | 1179篇 |
2021年 | 1354篇 |
2020年 | 1281篇 |
2019年 | 1057篇 |
2018年 | 1013篇 |
2017年 | 1328篇 |
2016年 | 1629篇 |
2015年 | 1693篇 |
2014年 | 2637篇 |
2013年 | 2744篇 |
2012年 | 3424篇 |
2011年 | 3711篇 |
2010年 | 2595篇 |
2009年 | 2562篇 |
2008年 | 2323篇 |
2007年 | 3185篇 |
2006年 | 3198篇 |
2005年 | 2983篇 |
2004年 | 2528篇 |
2003年 | 2269篇 |
2002年 | 1950篇 |
2001年 | 1689篇 |
2000年 | 1411篇 |
1999年 | 1194篇 |
1998年 | 949篇 |
1997年 | 689篇 |
1996年 | 630篇 |
1995年 | 576篇 |
1994年 | 405篇 |
1993年 | 237篇 |
1992年 | 182篇 |
1991年 | 148篇 |
1990年 | 132篇 |
1989年 | 85篇 |
1988年 | 45篇 |
1987年 | 39篇 |
1986年 | 33篇 |
1985年 | 9篇 |
1984年 | 16篇 |
1983年 | 7篇 |
1982年 | 5篇 |
1981年 | 17篇 |
1980年 | 10篇 |
1979年 | 4篇 |
1977年 | 2篇 |
1959年 | 5篇 |
1957年 | 1篇 |
1951年 | 6篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
Aleksey Prizov Elena Tchetina Ilya Eremin Nikolay Zagorodniy Andrey Pulin Evgeniy Belyak Evgeniy Goncharov Konstantin Kotenko Ivan Smyshlyaev Svetlana Glukhova Aleksandr Lila 《International journal of molecular sciences》2022,23(21)
Functional outcomes and synovial fluid (SF) cytokine concentrations in response to platelet-rich plasma (PRP) or stromal vascular fraction (SVF) post-treatments following open wedge high tibial osteotomy (HTO) in 20 patients with knee osteoarthritis (OA) were examined. Six weeks after surgery, the knees of 10 patients were injected with autologous PRP (PRP subgroup), while another 10 patients were injected with autologous SVF (SVF subgroup) and monitored for 1.5 years. Pain assessment (VAS score) and functional activity (KOOS, KSS, Outerbridge, and Koshino scores) were applied. PRP subgroup performed better compared with the SVF subgroup according to KOOS, KSS, and VAS scores, while the SVF subgroup demonstrated better results according to Outerbridge and Koshino testing and produced more pronounced cartilage regeneration in the medial condyle and slowed down cartilage destruction in its lateral counterpart. SF was collected before and one week after PRP or SVF injections and tested for concentrations of 41 cytokines (Multiplex Assay). In the PRP subgroup, a significant decrease in IL-6 and CXCL10 synovial concentrations was accompanied by an increase in IL-15, sCD40L, and PDGF-AB/BB amounts. The SVF subgroup demonstrated a significant decrease in synovial TNFα, FLT-3L, MIP-1β, RANTES, and VEGF concentrations while SF concentrations of MCP-1 and FGF2 increased. Both post-treatments have a potential for increased tissue regeneration, presumably due to the downregulation of inflammation and augmentation of synovial growth factor concentrations. 相似文献
32.
Franjo Banovic Sandrin Schulze Mobarak Abu Mraheil Torsten Hain Trinad Chakraborty Vronique Orian-Rousseau Selina Moroniak Christel Weiss Hiroshi Ishikawa Horst Schroten Rüdiger Adam Christian Schwerk 《International journal of molecular sciences》2022,23(21)
The human central nervous system (CNS) is separated from the blood by distinct cellular barriers, including the blood–brain barrier (BBB) and the blood–cerebrospinal fluid (CFS) barrier (BCSFB). Whereas at the center of the BBB are the endothelial cells of the brain capillaries, the BCSFB is formed by the epithelium of the choroid plexus. Invasion of cells of either the BBB or the BCSFB is a potential first step during CNS entry by the Gram-positive bacterium Listeria monocytogenes (Lm). Lm possesses several virulence factors mediating host cell entry, such as the internalin protein family—including internalin (InlA), which binds E-cadherin (Ecad) on the surface of target cells, and internalin B (InlB)—interacting with the host cell receptor tyrosine kinase Met. A further family member is internalin (InlF), which targets the intermediate filament protein vimentin. Whereas InlF has been shown to play a role during brain invasion at the BBB, its function during infection at the BCSFB is not known. We use human brain microvascular endothelial cells (HBMEC) and human choroid plexus epithelial papilloma (HIBCPP) cells to investigate the roles of InlF and vimentin during CNS invasion by Lm. Whereas HBMEC present intracellular and surface vimentin (besides Met), HIBCPP cells do not express vimentin (except Met and Ecad). Treatment with the surface vimentin modulator withaferin A (WitA) inhibited invasion of Lm into HBMEC, but not HIBCPP cells. Invasion of Lm into HBMEC and HIBCPP cells is, however, independent of InlF, since a deletion mutant of Lm lacking InlF did not display reduced invasion rates. 相似文献
33.
Chang-Gun Lee Do-Wan Kim Jeonghyun Kim Laxmi Prasad Uprety Kang-Il Oh Shivani Singh Jisu Yoo Hyun-Seok Jin Tae Hyun Choi Eunkuk Park Seon-Yong Jeong 《International journal of molecular sciences》2022,23(22)
Osteoporosis is a disease caused by impaired bone remodeling that is especially prevalent in elderly and postmenopausal women. Although numerous chemical agents have been developed to prevent osteoporosis, arguments remain regarding their side effects. Here, we demonstrated the effects of loganin, a single bioactive compound isolated from Cornus officinalis, on osteoblast and osteoclast differentiation in vitro and on ovariectomy (OVX)-induced osteoporosis in mice in vivo. Loganin treatment increased the differentiation of mouse preosteoblast cells into osteoblasts and suppressed osteoclast differentiation in primary monocytes by regulating the mRNA expression levels of differentiation markers. Similar results were obtained in an osteoblast–osteoclast co-culture system, which showed that loganin enhanced alkaline phosphatase (ALP) activity and reduced TRAP activity. In in vivo experiments, the oral administration of loganin prevented the OVX-induced loss of bone mineral density (BMD) and microstructure in mice and improved bone parameters. In addition, loganin significantly increased the serum OPG/RANKL ratio and promoted osteogenic activity during bone remodeling. Our findings suggest that loganin could be used as an alternative treatment to protect against osteoporosis. 相似文献
34.
Milomir O. Simovic Michael J. Falabella Tuan D. Le Jurandir J. DalleLucca Yansong Li 《International journal of molecular sciences》2022,23(21)
Preclinical and clinical studies have shown that traumatic hemorrhage (TH) induces early complement cascade activation, leading to inflammation-associated multiple-organ dysfunction syndrome (MODS). Several previous studies have demonstrated the beneficial effects of complement inhibition in anesthetized (unconscious) animal models of hemorrhage. Anesthetic agents profoundly affect the immune response, microcirculation response, and coagulation patterns and thereby may confound the TH research data acquired. However, no studies have addressed the effect of complement inhibition on inflammation-driven MODS in a conscious model of hemorrhage. This study investigated whether early administration of decay-accelerating factor (CD55/DAF, a complement C3/C5 inhibitor) alleviates hemorrhage-induced organ damage and how DAF modulates hemorrhage-induced organ damage. DAF was administered to unanesthetized male Sprague Dawley rats subjected to pressure-controlled hemorrhage followed by a prolonged (4 h) hypotensive resuscitation with or without lactated Ringer’s (LR). We assessed DAF effects on organ protection, tissue levels of complement synthesis and activation, T lymphocyte infiltration, fluid resuscitation requirements, and metabolic acidosis. Hemorrhage with (HR) or without (H) LR resuscitation resulted in significantly increased C3, C5a, and C5b-9 deposition in the lung and intestinal tissues. HR rats had significantly higher tissue levels of complement activation/deposition (particularly C5a and C5b-9 in the lung tissues), a higher but not significant amount of C3 and C5b-9 pulmonary microvascular deposition, and relatively severe injury in the lung and intestinal tissues compared to H rats. DAF treatment significantly reduced tissue C5b-9 formation and C3 deposition in the H or HR rats and decreased tissue levels of C5a and C3 mRNA in the HR rats. This treatment prevented the injury of these organs, improved metabolic acidosis, reduced fluid resuscitation requirements, and decreased T-cell infiltration in lung tissues. These findings suggest that DAF has the potential as an organ-protective adjuvant treatment for TH during prolonged damage control resuscitation. 相似文献
35.
Lorenzo Moretti Davide Bizzoca Alessandro Geronimo Francesco Luca Moretti Edoardo Monaco Giuseppe Solarino Biagio Moretti 《International journal of molecular sciences》2022,23(17)
Osteoarthritis (OA) is a joint degenerative disease that most affects old age. The study of proteomics in synovial fluid (SF) has the task of providing additional elements to diagnose and predict the progress of OA. This review aims to identify the most significant biomarkers in the study of OA and to stimulate their routine use. Some of the major components of the ECM, such as proteoglycan aggrecan and decorin, were found considerably reduced in OA. Some biomarkers have proved useful for staging the temporality of OA: Periostin was found to be increased in early OA, while CRTA1 and MMPs were found to be increased in late OA. In its natural attempt at tissue regeneration, Collagen III was found to be increased in early OA while decreased in late OA. Some molecules studied in other areas, such as ZHX3 (oncological marker), LYVE1, and VEGF (lymph and angiogenesis markers), also have been found to be altered in OA. It also has been recorded that alteration of the hormonal pathway, using a dosage of PPAR-γ and RETN, can influence the evolution of OA. IL-1, one of the most investigated biomarkers in OA-SF, is not as reliable as a target of OA in recent studies. The study of biomarkers in SF appears to be, in combination with the clinical and radiological aspects, an additional weapon to address the diagnosis and staging of OA. Therefore, it can guide us more appropriately towards the indication of arthroplasty in patients with OA. 相似文献
36.
Tomohiro Fujii Jun Nishikawa Soichiro Fukuda Naoto Kubota Junzo Nojima Koichi Fujisawa Ryo Ogawa Atsushi Goto Koichi Hamabe Shinichi Hashimoto Aung Phyo Wai Hisashi Iizasa Hironori Yoshiyama Kohei Sakai Yutaka Suehiro Takahiro Yamasaki Taro Takami 《International journal of molecular sciences》2022,23(18)
DNA methylation of both viral and host DNA is one of the major mechanisms involved in the development of Epstein–Barr virus-associated gastric carcinoma (EBVaGC); thus, epigenetic treatment using demethylating agents would seem to be promising. We have verified the effect of , which was discovered by screening for demethylating agents. MC180295 inhibited cell growth of the EBVaGC cell lines YCCEL1 and SNU719 in a dose-dependent manner. In a cell cycle analysis, growth arrest and apoptosis were observed in both YCCEL1 and SNU719 cells treated with MC180295. MKN28 cells infected with EBV were sensitive to MC180295 and showed more significant inhibition of cell growth compared to controls without EBV infection. Serial analysis of gene expression analysis showed the expression of genes belonging to the role of BRCA1 in DNA damage response and cell cycle control chromosomal replication to be significantly reduced after MC180295 treatment. We confirmed with quantitative PCR that the expression levels of BRCA2, FANCM, RAD51, TOP2A, and CDC45 were significantly decreased by MC180295. LMP1 and BZLF1 are EBV genes with expression that is epigenetically regulated, and MC180295 could up-regulate their expression. In conclusion, MC180295 inhibited the growth of EBVaGC cells by suppressing DNA repair and the cell cycle. MC180295相似文献
37.
Paige V. Hinton Katelyn J. Genoud James O. Early Fergal J. OBrien Oran D. Kennedy 《International journal of molecular sciences》2022,23(16)
Bone cells, in particular osteoblasts, are capable of communication with each other during bone growth and homeostasis. More recently it has become clear that they also communicate with other cell-types; including chondrocytes in articular cartilage. One way that this process is facilitated is by interstitial fluid movement within the pericellular and extracellular matrices. This stimulus is also an important mechanical signal in skeletal tissues, and is known to generate shear stresses at the micron-scale (known as fluid flow shear stresses (FFSS)). The primary aim of this study was to develop and characterize an in vitro bone–cartilage crosstalk system, to examine the effect of FFSS on these cell types. Specifically, we evaluated the response of osteoblasts and chondrocytes to FFSS and the effect of FFSS-induced soluble factors from the former, on the latter. This system will ultimately be used to help us understand the role of subchondral bone damage in articular cartilage degeneration. We also carried out a comparison of responses between cell lines and primary murine cells in this work. Our findings demonstrate that primary cells produce a more reliable and reproducible response to FFSS. Furthermore we found that at lower magnitudes , direct FFSS produces anabolic responses in both chondrocytes and osteoblasts, whereas higher levels produce more catabolic responses. Finally we show that exposure to osteoblast-derived factors in conditioned media experiments produced similarly catabolic changes in primary chondrocytes. 相似文献
38.
河南某金矿具有嵌布关系复杂、氧化率高、泥化严重等特点,属于复杂难选泥质高氧化型金矿,选矿厂浮选指标不理想。为提高此类矿石的选矿回收率,开展了详细的实验研究,实验研究结果表明:采用单一浸出工艺和预氧化+浸出工艺均很难获得理想的浸出指标,Au浸出率仅为77.46%、80.28%;采用焙烧+浸出工艺可显著提高浸出指标,Au浸出率为93.66%,但技术经济性较差;采用浮选+浸出工艺可获得较为理想的指标,Au总回收率为94.25%,且工艺流程可操作性强。因此,浮选+浸出工艺对此类矿石具有较好的适应性,不仅可回收高度弥散分布在硫化物和脉石矿物中的超细微粒级金,而且粗粒级颗粒金也得到较好的回收。本研究为矿山企业的生产实践提供了重要借鉴。 相似文献
39.
煤层瓦斯测压下向钻孔积水会导致测压不准,研究既能排水又不影响测压进程和测压结果的装置是下向钻孔测压亟待解决的难题。设计了自动排水装置,利用弹性膜实时感知排水时机, 实现了自动化排水;试验研究了弹性膜弹性参数,确定膜的最佳厚度为0.3~1.0 mm;基于气体压力差与毛细作用力原理,推算了最优排水区间;在此基础上研制出一种煤层瓦斯测压下向钻孔自动排水实验装置并开展排水试验。试验结果表明:在测压气室气压为0.152×105 Pa,排水管管径为15 mm,毛细管内径为0.2 mm、数量为950根时,排水速度为0.444 3 cm3/s,该装置可以实现连续缓慢排水。
相似文献40.
针对煤矿井下钻孔作业场景特点,分别选取了基于煤岩图像特征和基于钻进参数反馈的识别方法。为了提高煤岩界面识别准确性,对前述的2种识别方法采用深度学习模型实现了2种异构信息的耦合识别。耦合识别模型基于神经网络模型构建,以CNN卷积神经网络为基础,扩展得到深度残差神经网络模型,其结构主要由骨干网络、颈部网络、头部网络3个部分构成。通过数据库模型训练,得到最终识别方法。通过在煤矿井下进行现场钻孔试验,验证了识别方法的准确性,其中煤岩界面识别准确率达92%。
相似文献