全文获取类型
收费全文 | 54649篇 |
免费 | 4720篇 |
国内免费 | 2143篇 |
专业分类
电工技术 | 2877篇 |
技术理论 | 7篇 |
综合类 | 3226篇 |
化学工业 | 9445篇 |
金属工艺 | 3113篇 |
机械仪表 | 3501篇 |
建筑科学 | 3634篇 |
矿业工程 | 1593篇 |
能源动力 | 1737篇 |
轻工业 | 3547篇 |
水利工程 | 790篇 |
石油天然气 | 3156篇 |
武器工业 | 463篇 |
无线电 | 6663篇 |
一般工业技术 | 7327篇 |
冶金工业 | 2808篇 |
原子能技术 | 746篇 |
自动化技术 | 6879篇 |
出版年
2024年 | 265篇 |
2023年 | 977篇 |
2022年 | 1637篇 |
2021年 | 2333篇 |
2020年 | 1735篇 |
2019年 | 1480篇 |
2018年 | 1696篇 |
2017年 | 1917篇 |
2016年 | 1758篇 |
2015年 | 2201篇 |
2014年 | 2869篇 |
2013年 | 3460篇 |
2012年 | 3597篇 |
2011年 | 3919篇 |
2010年 | 3256篇 |
2009年 | 3133篇 |
2008年 | 3077篇 |
2007年 | 2900篇 |
2006年 | 2786篇 |
2005年 | 2378篇 |
2004年 | 1710篇 |
2003年 | 1458篇 |
2002年 | 1459篇 |
2001年 | 1239篇 |
2000年 | 1254篇 |
1999年 | 1247篇 |
1998年 | 1100篇 |
1997年 | 912篇 |
1996年 | 838篇 |
1995年 | 648篇 |
1994年 | 548篇 |
1993年 | 357篇 |
1992年 | 298篇 |
1991年 | 222篇 |
1990年 | 193篇 |
1989年 | 154篇 |
1988年 | 125篇 |
1987年 | 75篇 |
1986年 | 82篇 |
1985年 | 43篇 |
1984年 | 32篇 |
1983年 | 32篇 |
1982年 | 28篇 |
1981年 | 17篇 |
1980年 | 11篇 |
1979年 | 8篇 |
1977年 | 10篇 |
1976年 | 13篇 |
1973年 | 5篇 |
1970年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
Journal of Computer Science and Technology - DOACROSS loops are significant parts in many important scientific and engineering applications, which are generally exploited pipeline/wave-front... 相似文献
22.
Shibo Lv Yuyang Miao Dr. Dapeng Liu Prof. Fengling Song 《Chembiochem : a European journal of chemical biology》2020,21(15):2098-2110
Photothermal therapy (PTT) has attracted great attention due to its noninvasive and effective use against cancer. Various photothermal agents (PTAs) including organic and inorganic PTAs have been developed in the last decades. Organic PTAs based on small-molecule dyes exhibit great potential for future clinical applications considering their good biocompatibility and easy chemical modification or functionalization. In this review, we discuss the recent progress of organic PTAs based on small-molecule dyes for enhanced PTT. We summarize the strategies to improve the light penetration of PTAs, methods to enhance their photothermal conversion efficiency, how to optimize PTAs’ delivery into deep tumors, and how to resist photobleaching under repeated laser irradiation. We hope that this review can rouse the interest of researchers in the field of PTAs based on small-molecule dyes and help them to fabricate next-generation PTAs for noninvasive cancer therapy. 相似文献
23.
24.
Thermal barrier coatings (TBCs) produced by electron beam physical vapor deposition (EB-PVD) or plasma spray (PS) usually suffer from molten calcium-magnesium-alumino-silicate (CMAS) attack. In this study, columnar structured YSZ coatings were fabricated by plasma spray physical vapor deposition (PS-PVD). The coatings were CMAS-infiltrated at 1250?°C for short terms (1, 5, 30?min). The wetting and spreading dynamics of CMAS melt on the coating surface was in-situ investigated using a heating microscope. The results indicate that the spreading evolution of CMAS melt can be described in terms of two stages with varied time intervals and spreading velocities. Besides, the PS-PVD columnar coating (~100?μm thick) was fully penetrated by CMAS melt within 1?min. After the CMAS attack for 30?min, the original feathered-YSZ grains (tetragonal phase) in both PS-PVD and EB-PVD coatings were replaced by globular shaped monoclinic ZrO2 grains in the interaction regions. 相似文献
25.
26.
Multimedia Tools and Applications - In Wyner-Ziv (WZ) video coding, decoder side information (SI) takes a key role in a WZ video codec among other building blocks. In this paper, we review the... 相似文献
27.
Longzhi Li Xiaowei Jiang Zhiguo Bian Jianwei Wang Fumao Wang Zhanlong Song 《Drying Technology》2019,37(2):173-185
Microwave lignite drying with assistance of biomass-derived char was addressed and effect of bio-char on drying rate and energy consumption was investigated in this work. Effective diffusion coefficient and activation energy for the drying process were also analyzed. The results indicated the drying process was largely dependent on the variation of sample temperature. Bio-char originated from pine wood was most favorable for lignite drying, considering its better promoting effect and advanced security. There existed an optimal bio-char addition ratio for drying process at different power. The corresponding optimal ratio was 10% at 231?W and 15% at 385?W, at which the biggest drying rate and the least energy consumption were reached. It was compared lignite drying initiated at 385?W was better for energy conservation. Effective diffusivity was improved and activation energy was simultaneously reduced, with the addition of bio-char. The minimum activation energy was 15.54?W?·?g?1, which was gained at bio-char addition ratio of 10%. The results revealed the effect of bio-char on depressing activation energy could rival that of metal-based additives. The drying process with assistance of microwave and bio-char could present technical and economical benefits on lignite upgrading. 相似文献
28.
Min-Kyung Kang Soo-Il Kim Su Yeon Oh Woojin Na Young-Hee Kang 《International journal of molecular sciences》2020,21(22)
Podocyte injury inevitably results in leakage of proteins from the glomerular filter and is vital in the pathogenesis of diabetic nephropathy (DN). The underlying mechanisms of podocyte injury facilitate finding of new therapeutic targets for DN treatment and prevention. Tangeretin is an O-polymethoxylated flavone present in citrus peels with anti-inflammatory and antioxidant properties. This study investigated the renoprotective effects of tangeretin on epithelial-to-mesenchymal transition-mediated podocyte injury and fibrosis through oxidative stress and hypoxia caused by hyperglycemia. Mouse podocytes were incubated in media containing 33 mM glucose in the absence and presence of 1–20 μM tangeretin for up to 6 days. The in vivo animal model employed db/db mice orally administrated with 10 mg/kg tangeretin for 8 weeks. Non-toxic tangeretin inhibited glucose-induced expression of the mesenchymal markers of N-cadherin and α-smooth muscle actin in podocytes. However, the reduced induction of the epithelial markers of E-cadherin and P-cadherin was restored by tangeretin in diabetic podocytes. Further, tangeretin enhanced the expression of the podocyte slit diaphragm proteins of nephrin and podocin down-regulated by glucose stimulation. The transmission electron microscopic images revealed that foot process effacement and loss of podocytes occurred in diabetic mouse glomeruli. However, oral administration of 10 mg/kg tangeretin reduced urine albumin excretion and improved foot process effacement of diabetic podocytes through inhibiting loss of slit junction and adherenes junction proteins. Glucose enhanced ROS production and HIF-1α induction in podocytes, leading to induction of oxidative stress and hypoxia. Similarly, in diabetic glomeruli reactive oxygen species (ROS) production and HIF-1α induction were observed. Furthermore, hypoxia-evoking cobalt chloride induced epithelial-to-mesenchymal transition (EMT) process and loss of slit diaphragm proteins and junction proteins in podocytes, which was inhibited by treating submicromolar tangeretin. Collectively, these results demonstrate that tangeretin inhibited podocyte injury and fibrosis through blocking podocyte EMT caused by glucose-induced oxidative stress and hypoxia. 相似文献
29.
30.