全文获取类型
收费全文 | 486668篇 |
免费 | 5360篇 |
国内免费 | 1408篇 |
专业分类
电工技术 | 9234篇 |
综合类 | 398篇 |
化学工业 | 68909篇 |
金属工艺 | 22081篇 |
机械仪表 | 17405篇 |
建筑科学 | 11555篇 |
矿业工程 | 2735篇 |
能源动力 | 12096篇 |
轻工业 | 36308篇 |
水利工程 | 5114篇 |
石油天然气 | 7979篇 |
武器工业 | 25篇 |
无线电 | 59169篇 |
一般工业技术 | 99620篇 |
冶金工业 | 86469篇 |
原子能技术 | 10259篇 |
自动化技术 | 44080篇 |
出版年
2021年 | 3530篇 |
2020年 | 2578篇 |
2019年 | 3261篇 |
2018年 | 12584篇 |
2017年 | 13138篇 |
2016年 | 9837篇 |
2015年 | 4266篇 |
2014年 | 6607篇 |
2013年 | 19184篇 |
2012年 | 12701篇 |
2011年 | 21550篇 |
2010年 | 18344篇 |
2009年 | 19101篇 |
2008年 | 19351篇 |
2007年 | 21072篇 |
2006年 | 12121篇 |
2005年 | 13974篇 |
2004年 | 12181篇 |
2003年 | 12011篇 |
2002年 | 10358篇 |
2001年 | 10437篇 |
2000年 | 9928篇 |
1999年 | 10420篇 |
1998年 | 26409篇 |
1997年 | 18526篇 |
1996年 | 14383篇 |
1995年 | 10607篇 |
1994年 | 9585篇 |
1993年 | 9402篇 |
1992年 | 6869篇 |
1991年 | 6626篇 |
1990年 | 6324篇 |
1989年 | 6203篇 |
1988年 | 6012篇 |
1987年 | 5066篇 |
1986年 | 4956篇 |
1985年 | 5560篇 |
1984年 | 5104篇 |
1983年 | 4897篇 |
1982年 | 4469篇 |
1981年 | 4490篇 |
1980年 | 4273篇 |
1979年 | 4191篇 |
1978年 | 3997篇 |
1977年 | 4736篇 |
1976年 | 6478篇 |
1975年 | 3438篇 |
1974年 | 3316篇 |
1973年 | 3276篇 |
1972年 | 2766篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
Multimedia Tools and Applications - Mammograms are the images used by radiologists to diagnose breast cancer. Breast cancer is one of the most common cancers in women. The early detection of breast... 相似文献
4.
Vijay Singh Sharanagat Prabhat K. Nema Lochan Singh Ankur Kumar 《International Journal of Food Science & Technology》2022,57(3):1654-1665
The effect of microwave roasting parameters (300, 450 and 600 W; 5, 10 and 15 min) on acrylamide content in sorghum grain was determined using High Pressure Liquid Chromatography (HPLC)-photo diode array (PDA) detector coupled with C-18 column. Samples roasted at 300 and 450 W did not possess acrylamide, whereas 600 W (15 min) favoured formation of 2740.19 µg/kg of acrylamide, levels far exceeding the defined European Union (EU) limits. The chronic daily intake (CDI) for acrylamide through consumption of such grain flour was 3.25–9.5-fold higher to Joint FAO/WHO Expert Committee on Food Additives (JECFA) defined high exposure limits. The margin of exposure (MOE) values ranged from 4.3 to 12.76 and from 11.07 to 32.27 for neoplastic and neurological effects, respectively, demonstrating high exposure and serious health concerns associated with dietary intake of this toxicant. This study assesses the risk for the Indian population and highlights the importance of optimising process parameters for food product to minimise such exposure risks. 相似文献
5.
6.
F.T. Munna Vidhya Selvanathan K. Sobayel Ghulam Muhammad Nilofar Asim Nowshad Amin Kamaruzzaman Sopian Md. Akhtaruzzaman 《Ceramics International》2021,47(8):11003-11009
In this study, dilute chemical bath deposition technique has been used to deposit CdZnS thin films on soda-lime glass substrates. The structural, morphological, optoelectronic properties of as-grown films have been investigated as a function of different Zn2+ precursor concentrations. The X-ray diffractogram of CdS thin-film reveals a peak corresponding to (002) plane with wurtzite structure, and the peak shift has been observed with the increase of the Zn2+ concentration upon formation of CdZnS thin film. From morphological studies, it has been revealed that the diluted chemical bath deposition technique provides homogeneous distribution of film on the substrate even at a lower concentration of Zn2+. Optical characterization has shown that the transparency of the film is influenced by Zn2+ concentration and when the Zn2+ concentration is varied from 0 M to 0.0256 M, bandgap values of resulting films range from 2.42 eV to 3.90 eV while. Furthermore, electrical properties have shown that with increasing zinc concentration the resistivity of the film increases. Finally, numerical simulation validates and suggests that CdZnS buffer layer with composition of 0.0032 M Zn2+ concentration would be a promising candidate in CIGS solar cell. 相似文献
7.
Prof. Andrea Baier Dr. Anne Kokel Dr. William Horton Ewa Gizińska Dr. Garima Pandey Prof. Ryszard Szyszka Prof. Béla Török Prof. Marianna Török 《ChemMedChem》2021,16(12):1927-1932
A set of novel hydrazone derivatives were synthesized and analyzed for their biological activities. The compounds were tested for their inhibitory effect on the phosphorylating activity of the protein kinase CK2, and their antioxidant activity was also determined in three commonly used assays. The hydrazones were evaluated for their radical scavenging against the DPPH, ABTS and peroxyl radicals. Several compounds have been identified as good antioxidants as well as potent protein kinase CK2 inhibitors. Most hydrazones containing a 4-N(CH3)2 residue or perfluorinated phenyl rings showed high activity in the radical-scavenging assays and possess nanomolar IC50 values in the kinase assays. 相似文献
8.
Wireless Personal Communications - Despite its various benefits, the Mobile Ad-hoc Network (MANET) has a number of obstacles due to its mobility, unstable topology, energy efficiency, and other... 相似文献
9.
Seredin P. V. Radam Ali Obaid Goloshchapov D. L. Len’shin A. S. Buylov N. S. Barkov K. A. Nesterov D. N. Mizerov A. M. Timoshnev S. N. Nikitina E. V. Arsentyev I. N. Sharafidinov Sh. Kukushkin S. A. Kasatkin I. A. 《Semiconductors》2022,56(4):253-258
Semiconductors - Abstract—In our work, we carry out a structural-spectroscopic study of AlGaN/GaN epitaxial layers grown by molecular-beam epitaxy with nitrogen-plasma activation on a hybrid... 相似文献
10.
Boltar K. O. Burlakov I. D. Iakovleva N. I. Vlasov P. V. Lazarev P. S. 《Journal of Communications Technology and Electronics》2022,67(9):1175-1184
Journal of Communications Technology and Electronics - In recent years, there has been a rapid improvement in photonics products due to the use of multilayer heterostructures grown on the basis of... 相似文献