全文获取类型
收费全文 | 402824篇 |
免费 | 5348篇 |
国内免费 | 1349篇 |
专业分类
电工技术 | 7569篇 |
综合类 | 314篇 |
化学工业 | 59534篇 |
金属工艺 | 16426篇 |
机械仪表 | 13491篇 |
建筑科学 | 8354篇 |
矿业工程 | 2154篇 |
能源动力 | 11531篇 |
轻工业 | 28482篇 |
水利工程 | 4263篇 |
石油天然气 | 7913篇 |
武器工业 | 17篇 |
无线电 | 49224篇 |
一般工业技术 | 82989篇 |
冶金工业 | 74967篇 |
原子能技术 | 9185篇 |
自动化技术 | 33108篇 |
出版年
2022年 | 2296篇 |
2021年 | 3880篇 |
2020年 | 2941篇 |
2019年 | 3796篇 |
2018年 | 6481篇 |
2017年 | 6473篇 |
2016年 | 6918篇 |
2015年 | 4317篇 |
2014年 | 7136篇 |
2013年 | 20038篇 |
2012年 | 11412篇 |
2011年 | 15267篇 |
2010年 | 12148篇 |
2009年 | 13721篇 |
2008年 | 14052篇 |
2007年 | 13816篇 |
2006年 | 12418篇 |
2005年 | 11113篇 |
2004年 | 10508篇 |
2003年 | 10420篇 |
2002年 | 9832篇 |
2001年 | 9739篇 |
2000年 | 9137篇 |
1999年 | 9525篇 |
1998年 | 24336篇 |
1997年 | 16715篇 |
1996年 | 12799篇 |
1995年 | 9517篇 |
1994年 | 8368篇 |
1993年 | 8380篇 |
1992年 | 6056篇 |
1991年 | 5695篇 |
1990年 | 5681篇 |
1989年 | 5319篇 |
1988年 | 5045篇 |
1987年 | 4421篇 |
1986年 | 4300篇 |
1985年 | 4812篇 |
1984年 | 4421篇 |
1983年 | 3995篇 |
1982年 | 3656篇 |
1981年 | 3729篇 |
1980年 | 3429篇 |
1979年 | 3326篇 |
1978年 | 3334篇 |
1977年 | 3751篇 |
1976年 | 4847篇 |
1975年 | 2850篇 |
1974年 | 2664篇 |
1973年 | 2731篇 |
排序方式: 共有10000条查询结果,搜索用时 140 毫秒
41.
Hideaki Kaneto Tomohiko Kimura Atsushi Obata Masashi Shimoda Kohei Kaku 《International journal of molecular sciences》2021,22(5)
While there are various kinds of drugs for type 2 diabetes mellitus at present, in this review article, we focus on metformin which is an insulin sensitizer and is often used as a first-choice drug worldwide. Metformin mainly activates adenosine monophosphate-activated protein kinase (AMPK) in the liver which leads to suppression of fatty acid synthesis and gluconeogenesis. Metformin activates AMPK in skeletal muscle as well, which increases translocation of glucose transporter 4 to the cell membrane and thereby increases glucose uptake. Further, metformin suppresses glucagon signaling in the liver by suppressing adenylate cyclase which leads to suppression of gluconeogenesis. In addition, metformin reduces autophagy failure observed in pancreatic β-cells under diabetic conditions. Furthermore, it is known that metformin alters the gut microbiome and facilitates the transport of glucose from the circulation into excrement. It is also known that metformin reduces food intake and lowers body weight by increasing circulating levels of the peptide hormone growth/differentiation factor 15 (GDF15). Furthermore, much attention has been drawn to the fact that the frequency of various cancers is lower in subjects taking metformin. Metformin suppresses the mechanistic target of rapamycin (mTOR) by activating AMPK in pre-neoplastic cells, which leads to suppression of cell growth and an increase in apoptosis in pre-neoplastic cells. It has been shown recently that metformin consumption potentially influences the mortality in patients with type 2 diabetes mellitus and coronavirus infectious disease (COVID-19). Taken together, metformin is an old drug, but multifaceted mechanisms of action of metformin have been unraveled one after another in its long history. 相似文献
42.
Golubev N. V. Ignat’eva E. S. Maurus A. A. Ziyatdinova M. Z. Lopatina E. V. Lorenzi R. Paleari A. Sigaev V. N. 《Glass and Ceramics》2021,77(11-12):415-418
Glass and Ceramics - The influence of Al2O3 as an additive and the heat-treatment regime on the luminescence spectra of gallate glass-ceramics was investigated. It is shown that its luminescence... 相似文献
43.
Ava Kwong Cecilia Y. S. Ho Vivian Y. Shin Chun Hang Au Tsun Leung Chan Edmond S. K. Ma 《International journal of molecular sciences》2021,22(2)
The germline carrier of the BRCA1 pathogenic mutation has been well proven to confer an increased risk of breast and ovarian cancer. Despite BRCA1 biallelic pathogenic mutations being extremely rare, they have been reported to be embryonically lethal or to cause Fanconi anemia (FA). Here we describe a patient who was a 48-year-old female identified with biallelic pathogenic mutations of the BRCA1 gene, with no or very subtle FA-features. She was diagnosed with ovarian cancer and breast cancer at the ages of 43 and 44 and had a strong family history of breast and gynecological cancers. 相似文献
44.
Klimis?S.?NtalianisEmail author Anastasios?D.?Doulamis Nikolaos?D.?Doulamis Nikos?E.?Mastorakis Athanasios?S.?Drigas 《Journal of Signal Processing Systems》2015,80(2):153-161
In this paper, we present a novel memory access reduction scheme (MARS) for two-dimension fast cosine transform (2-D FCT). It targets programmable DSPs with high memory-access latency. It reduces the number of memory accesses by: 1) reducing the number of weighting factors and 2) combining butterflies in vector-radix 2-D FCT pruning diagram from two stages to one stage with an efficient structure. Hardware platform based on general purpose processor is used to verify the effectiveness of the proposed method for vector-radix 2-D FCT pruning implementation. Experimental results validate the benefits of the proposed method with reduced memory access, less clock cycle and fewer memory space compared with the conventional implementation. 相似文献
45.
46.
47.
48.
Fermanelli Carla S. Galarza Emilce D. Pierella Liliana B. Renzini María S. Saux Clara 《Topics in Catalysis》2019,62(12-16):918-930
Topics in Catalysis - In this work, a simple thermal-catalytic system was used to valorize peanut shells (Arachis hypogaea), the residual biomass from the peanut industry. To accomplish this... 相似文献
49.
Gomes A. C. S. A. Costa L. C. Brito D. C. Frana R. J. Marques Mnica R. C. 《Polymer Bulletin》2020,77(4):1969-1981
Polymer Bulletin - In this study, we synthesized a new ion-imprinted polymer (IIP) based on introduction of amidoxime groups in acrylonitrile, complexation with Cd2+ ions and polymerization with... 相似文献
50.
Bankov S. E. Vesnik M. V. Kravchenko V. F. 《Journal of Communications Technology and Electronics》2020,65(4):398-405
Journal of Communications Technology and Electronics - Abstract—The article presents a rigorous numerical solution, using the Wiener–Hopf method, to the problem of plane wave... 相似文献