全文获取类型
收费全文 | 1067965篇 |
免费 | 13882篇 |
国内免费 | 2703篇 |
专业分类
电工技术 | 19535篇 |
综合类 | 915篇 |
化学工业 | 160854篇 |
金属工艺 | 45282篇 |
机械仪表 | 33434篇 |
建筑科学 | 24970篇 |
矿业工程 | 7149篇 |
能源动力 | 28137篇 |
轻工业 | 80366篇 |
水利工程 | 12438篇 |
石油天然气 | 22744篇 |
武器工业 | 62篇 |
无线电 | 119189篇 |
一般工业技术 | 217863篇 |
冶金工业 | 191758篇 |
原子能技术 | 23941篇 |
自动化技术 | 95913篇 |
出版年
2021年 | 9568篇 |
2020年 | 7315篇 |
2019年 | 9071篇 |
2018年 | 17797篇 |
2017年 | 17797篇 |
2016年 | 17923篇 |
2015年 | 10732篇 |
2014年 | 17813篇 |
2013年 | 48612篇 |
2012年 | 28405篇 |
2011年 | 40088篇 |
2010年 | 32477篇 |
2009年 | 35756篇 |
2008年 | 36834篇 |
2007年 | 36973篇 |
2006年 | 30079篇 |
2005年 | 27805篇 |
2004年 | 26546篇 |
2003年 | 26361篇 |
2002年 | 24838篇 |
2001年 | 24275篇 |
2000年 | 23031篇 |
1999年 | 23550篇 |
1998年 | 57639篇 |
1997年 | 40946篇 |
1996年 | 31848篇 |
1995年 | 24138篇 |
1994年 | 21716篇 |
1993年 | 21404篇 |
1992年 | 15827篇 |
1991年 | 15203篇 |
1990年 | 15029篇 |
1989年 | 14417篇 |
1988年 | 13824篇 |
1987年 | 12456篇 |
1986年 | 12068篇 |
1985年 | 13634篇 |
1984年 | 12433篇 |
1983年 | 11729篇 |
1982年 | 10759篇 |
1981年 | 10930篇 |
1980年 | 10467篇 |
1979年 | 10433篇 |
1978年 | 10179篇 |
1977年 | 11734篇 |
1976年 | 15036篇 |
1975年 | 8994篇 |
1974年 | 8797篇 |
1973年 | 8826篇 |
1972年 | 7606篇 |
排序方式: 共有10000条查询结果,搜索用时 12 毫秒
111.
The corrosion mechanisms of T24, T92, VM12, and AISI 304 steels are studied under the influence of NaCl–KCl, NaCl–Na2SO4, and KCl–K2SO4 salt mixtures in a dry air atmosphere at 650°C for 15 days. NaCl–KCl was the most aggressive deposit and AISI 304 stainless steel exhibited the highest corrosion resistance. There was no relation between the Cr content of the ferritic steels and their corrosion resistance in NaCl–KCl. In contrast, the resistance of high-Cr steels was better when exposed to NaCl–Na2SO4 and KCl–K2SO4. The high-Cr and the low-Cr steels were more susceptible to NaCl–Na2SO4 and to KCl–K2SO4, respectively. 相似文献
112.
113.
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
114.
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
115.
Catalysis Letters - A new zirconium based carbonaceous solid acid catalyst Zr@CC-PA with both Lewis and Bronsted acidic sites was prepared by simultaneous carbonization and phosphonation of glucose... 相似文献
116.
Ivashchuk O. A. Ivashchuk O. D. Fedorov V. I. Shtana A. I. 《Russian Engineering Research》2020,40(11):970-972
Russian Engineering Research - Models based on regression analysis for predicting the operational efficiency of high-pressure roller crushers are considered. A systematized and structured... 相似文献
117.
Popov N. N. Presnyakov D. V. Lar’kin V. F. 《Journal of Machinery Manufacture and Reliability》2020,49(3):232-236
Journal of Machinery Manufacture and Reliability - A device based on smart alloys has been designed for use in machine building items, in particular, in nuclear engineering, for preventing... 相似文献
118.
Bakirov Zh. B. Tanirbergenova A. A. 《Journal of Machinery Manufacture and Reliability》2020,49(3):263-271
Journal of Machinery Manufacture and Reliability - The problem of calculating the reliability and fatigue life of machine parts by the fatigue failure under random changes in the actual and limit... 相似文献
119.
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
120.