全文获取类型
收费全文 | 17283篇 |
免费 | 1516篇 |
国内免费 | 848篇 |
专业分类
电工技术 | 845篇 |
技术理论 | 1篇 |
综合类 | 882篇 |
化学工业 | 2789篇 |
金属工艺 | 1011篇 |
机械仪表 | 877篇 |
建筑科学 | 1080篇 |
矿业工程 | 298篇 |
能源动力 | 528篇 |
轻工业 | 1746篇 |
水利工程 | 342篇 |
石油天然气 | 559篇 |
武器工业 | 106篇 |
无线电 | 1745篇 |
一般工业技术 | 2312篇 |
冶金工业 | 1884篇 |
原子能技术 | 175篇 |
自动化技术 | 2467篇 |
出版年
2024年 | 104篇 |
2023年 | 320篇 |
2022年 | 754篇 |
2021年 | 968篇 |
2020年 | 654篇 |
2019年 | 511篇 |
2018年 | 563篇 |
2017年 | 659篇 |
2016年 | 576篇 |
2015年 | 724篇 |
2014年 | 951篇 |
2013年 | 1094篇 |
2012年 | 1178篇 |
2011年 | 1270篇 |
2010年 | 1044篇 |
2009年 | 1000篇 |
2008年 | 924篇 |
2007年 | 842篇 |
2006年 | 766篇 |
2005年 | 609篇 |
2004年 | 435篇 |
2003年 | 363篇 |
2002年 | 343篇 |
2001年 | 313篇 |
2000年 | 249篇 |
1999年 | 253篇 |
1998年 | 505篇 |
1997年 | 382篇 |
1996年 | 261篇 |
1995年 | 170篇 |
1994年 | 136篇 |
1993年 | 133篇 |
1992年 | 58篇 |
1991年 | 41篇 |
1990年 | 55篇 |
1989年 | 41篇 |
1988年 | 33篇 |
1987年 | 33篇 |
1986年 | 24篇 |
1985年 | 33篇 |
1984年 | 26篇 |
1983年 | 22篇 |
1982年 | 19篇 |
1981年 | 41篇 |
1980年 | 23篇 |
1979年 | 16篇 |
1978年 | 16篇 |
1977年 | 31篇 |
1976年 | 32篇 |
1975年 | 13篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
原油标准体积管结蜡造成的后果及解决方法 总被引:1,自引:0,他引:1
徐涤 《天津城市建设学院学报》2000,6(1):53-55
探讨了原油动态计量中标准体积管结蜡所引起的误差、原因分析和经济损失,提出了解决问题的办法。 相似文献
72.
针对高速列车焊接构架用钢的性能要求,设计了一种低成本的Mn-Cu微合金低碳钢,并对该实验钢的连续冷却转变规律以及冷却工艺对组织演变的影响进行了研究.结果表明,实验钢在较宽的冷速范围(1~30℃/s)内均可以获得先共析铁素体和中温相变组织.冷却速度和卷取温度对最终组织形态和细化有着重要影响,轧制结束后立即加速冷却至500~600℃,再缓冷,可以获得以细小准多边形铁素体、针状铁素体和粒状贝氏体为主的混合组织.经实验室控轧控冷验证了具有该组织形态的12 mm中厚钢板屈服强度可达540 MPa,同时拥有良好的塑性和低温韧性. 相似文献
73.
A three-step cooling pattern on the runout table(ROT)was conducted for the hot rolled TRIP steel.Microstructural evolution during thermomechanical controlled processing(TMCP)was investigated.Processing condition of controlled cooling on a ROT in the laboratory rolling mill was discussed.The results indicated that the microstructure containing polygonal ferrite,granular bainite and a significant amount of the stable retained austenite can be obtained through three-step cooling on the ROT after hot rolling.TMCP led to ferrite grain refinement.Controlled cooling after hot rolling resulted in the stability of the remaining austenite and a satisfactory TRIP effect.Excellent mechanical properties were obtained through TMCP for the hot rolled TRIP steel. 相似文献
74.
Karina Gonzlez-García Armando Lpez-Martínez Juan Manuel Velzquez-Enríquez Cecilia Zertuche-Martínez Gabriela Carrasco-Torres Luis Manuel Snchez-Navarro Saúl Villa-Trevio Rafael Baltirrez-Hoyos Vernica Rocío Vsquez-Garzn 《International journal of molecular sciences》2022,23(14)
Idiopathic pulmonary fibrosis (IPF) is a chronic lung disease characterized by parenchymal scarring, leading progressively to alveolar architecture distortion, respiratory failure, and eventually death. Currently, there is no effective treatment for IPF. Previously, 3′5-dimaleamylbenzoic acid (3′5-DMBA), a maleimide, demonstrated pro-apoptotic, anti-inflammatory, and anti-cancer properties; however, its potential therapeutic effects on IPF have not been addressed. Bleomycin (BLM) 100 U/kg was administered to CD1 mice through an osmotic minipump. After fourteen days of BLM administration, 3′5-DMBA (6 mg/kg or 10 mg/kg) and its vehicle carboxymethylcellulose (CMC) were administered intragastrically every two days until day 26. On day 28, all mice were euthanized. The 3′5-DMBA effect was assessed by histological and immunohistochemical staining, as well as by RT-qPCR. The redox status on lung tissue was evaluated by determining the glutathione content and the GSH/GSSG ratio. 3′5-DMBA treatment re-established typical lung histological features and decreased the expression of BLM-induced fibrotic markers: collagen, α-SMA, and TGF-β1. Furthermore, 3′5-DMBA significantly reduced the expression of genes involved in fibrogenesis. In addition, it decreased reduced glutathione and increased oxidized glutathione content without promoting oxidative damage to lipids, as evidenced by the decrease in the lipid peroxidation marker 4-HNE. Therefore, 3′5-DMBA may be a promising candidate for IPF treatment. 相似文献
75.
Agnese Filippello Stefania Di Mauro Alessandra Scamporrino Sebastiano Alfio Torrisi Gian Marco Leggio Antonino Di Pino Roberto Scicali Maurizio Di Marco Roberta Malaguarnera Francesco Purrello Salvatore Piro 《International journal of molecular sciences》2022,23(14)
Intestinal cell dysfunctions involved in obesity and associated diabetes could be correlated with impaired intestinal cell development. To date, the molecular mechanisms underlying these dysfunctions have been poorly investigated because of the lack of a good model for studying obesity. The main aim of this study was to investigate the effects of lipotoxicity on intestinal cell differentiation in small intestinal organoid platforms, which are used to analyze the regulation of cell differentiation. Mouse intestinal organoids were grown in the presence/absence of high palmitate concentrations (0.5 mM) for 48 h to simulate lipotoxicity. Palmitate treatment altered the expression of markers involved in the differentiation of enterocytes and goblet cells in the early (Hes1) and late (Muc2) phases of their development, respectively, and it modified enterocytes and goblet cell numbers. Furthermore, the expression of enteroendocrine cell progenitors (Ngn3) and I cells (CCK) markers was also impaired, as well as CCK-positive cell numbers and CCK secretion. Our data indicate, for the first time, that lipotoxicity simultaneously influences the differentiation of specific intestinal cell types in the gut: enterocytes, goblet cells and CCK cells. Through this study, we identified novel targets associated with molecular mechanisms affected by lipotoxicity that could be important for obesity and diabetes therapy. 相似文献
76.
结合江苏油田导向钻井技术现场试验中采用的三种典型的滑动导向钻具组合,在计算复合钻井导向力的基础上,探讨了两个主要因素对复合钻井导向力的影响规律,理论计算结果与现场试验结果基本吻合,通过设计钻具组合的结构和施工参数,可以提高井眼轨迹控制精度。 相似文献
77.
78.
改进自适应中值滤波的图像去噪 总被引:1,自引:0,他引:1
传统自适应中值滤波的最大最小窗口尺寸固定,并且其最大最小窗口相差较大时,运算时间较长,去噪效果并小一定最佳。本文针对传统自适应中值滤波算法的不足,提出了改进自适应中值滤波算法,首先根据椒盐噪声的分布特点,从单幅含椒盐噪声图像中估算出椒盐噪声的浓度,并分析噪声浓度与自适应中值滤波窗口尺寸之间的关系,建立它们之间的函数关系一其次根据噪声浓度确定自适应中值滤波的最大最小窗口尺寸,最后对图像进行自适应中值滤波:实验结果表明本文算法运算时间随着噪声浓度的变化而变化,而且从PSNR角度来看本文去噪效果比传统自适应中值滤波效果较好。 相似文献
79.
Mariantonia Logozzi Rossella Di Raimo Davide Mizzoni Stefano Fais 《International journal of molecular sciences》2022,23(9)
Research in science and medicine is witnessing a massive increases in literature concerning extracellular vesicles (EVs). From a morphological point of view, EVs include extracellular vesicles of a micro and nano sizes. However, this simplistic classification does not consider both the source of EVs, including the cells and the species from which Evs are obtained, and the microenvironmental condition during EV production. These two factors are of crucial importance for the potential use of Evs as therapeutic agents. In fact, the choice of the most suitable Evs for drug delivery remains an open debate, inasmuch as the use of Evs of human origin may have at least two major problems: (i) autologous Evs from a patient may deliver dangerous molecules; and (ii) the production of EVs is also limited to cell factory conditions for large-scale industrial use. Recent literature, while limited to only a few papers, when compared to the papers on the use of human EVs, suggests that plant-derived nanovesicles (PDNV) may represent a valuable tool for extensive use in health care. 相似文献
80.
Valentina Masola Mario Bonomini Silvio Borrelli Lorenzo Di Liberato Luigi Vecchi Maurizio Onisto Giovanni Gambaro Roberto Palumbo Arduino Arduini 《International journal of molecular sciences》2022,23(9)
Peritoneal dialysis (PD) is an efficient renal replacement therapy for patients with end-stage renal disease. Even if it ensures an outcome equivalent to hemodialysis and a better quality of life, in the long-term, PD is associated with the development of peritoneal fibrosis and the consequents patient morbidity and PD technique failure. This unfavorable effect is mostly due to the bio-incompatibility of PD solution (mainly based on high glucose concentration). In the present review, we described the mechanisms and the signaling pathway that governs peritoneal fibrosis, epithelial to mesenchymal transition of mesothelial cells, and angiogenesis. Lastly, we summarize the present and future strategies for developing more biocompatible PD solutions. 相似文献