全文获取类型
收费全文 | 464381篇 |
免费 | 11007篇 |
国内免费 | 4148篇 |
专业分类
电工技术 | 11097篇 |
技术理论 | 2篇 |
综合类 | 4412篇 |
化学工业 | 69925篇 |
金属工艺 | 20007篇 |
机械仪表 | 17493篇 |
建筑科学 | 12962篇 |
矿业工程 | 4268篇 |
能源动力 | 13166篇 |
轻工业 | 32375篇 |
水利工程 | 5316篇 |
石油天然气 | 11770篇 |
武器工业 | 541篇 |
无线电 | 56596篇 |
一般工业技术 | 90314篇 |
冶金工业 | 77765篇 |
原子能技术 | 9797篇 |
自动化技术 | 41730篇 |
出版年
2022年 | 3972篇 |
2021年 | 6389篇 |
2020年 | 4848篇 |
2019年 | 5494篇 |
2018年 | 8332篇 |
2017年 | 8532篇 |
2016年 | 8776篇 |
2015年 | 6753篇 |
2014年 | 10110篇 |
2013年 | 23556篇 |
2012年 | 15404篇 |
2011年 | 19621篇 |
2010年 | 15754篇 |
2009年 | 17169篇 |
2008年 | 17370篇 |
2007年 | 17016篇 |
2006年 | 16003篇 |
2005年 | 14080篇 |
2004年 | 12565篇 |
2003年 | 12159篇 |
2002年 | 11383篇 |
2001年 | 11142篇 |
2000年 | 10651篇 |
1999年 | 11184篇 |
1998年 | 25763篇 |
1997年 | 17929篇 |
1996年 | 13899篇 |
1995年 | 10436篇 |
1994年 | 9167篇 |
1993年 | 8924篇 |
1992年 | 6467篇 |
1991年 | 6050篇 |
1990年 | 5924篇 |
1989年 | 5521篇 |
1988年 | 5216篇 |
1987年 | 4520篇 |
1986年 | 4389篇 |
1985年 | 4865篇 |
1984年 | 4449篇 |
1983年 | 4009篇 |
1982年 | 3680篇 |
1981年 | 3745篇 |
1980年 | 3448篇 |
1979年 | 3334篇 |
1978年 | 3341篇 |
1977年 | 3755篇 |
1976年 | 4860篇 |
1975年 | 2858篇 |
1974年 | 2665篇 |
1973年 | 2734篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
Blagoveshchenskii D. I. Kozlovskii V. N. Vasin S. A. 《Russian Engineering Research》2021,41(12):1255-1259
Russian Engineering Research - Digital tools for managing improvements in automobile production are developed. An operative tool provides warnings regarding the operational quality of the vehicles... 相似文献
22.
Abdulrahman S. Albidah 《Ceramics International》2021,47(11):14923-14943
The growth of demand for concrete raises concerns about the consumption of natural resources and ordinary Portland cement. Geopolymer composites show promise as a sustainable alternative for conventional cement concrete. Considering the wide range of potential geopolymer composites applications (including suitability for transportation infrastructure, underwater applications, repair and rehabilitation of structures as well as recent developments in 3D printing), the desired fresh and mechanical properties of the geopolymer composite may vary between applications: for example, rapid setting can be a merit for certain applications and a demerit for others. Therefore, the desired fresh and mechanical properties (e.g., workability, setting time, compressive strength, etc.) can be controlled for a given geopolymer source material through its partial substitution by natural or by-product materials. Recognizing the critical role of various replacement materials in enhancing the potential applications of geopolymer composites, the present review was undertaken to quantify and understand the effect of partial replacement by fly ash, metakaolin, kaolin, red mud, slag, ordinary Portland cement, and silica fume on the setting time, workability, compressive strength and flexural strength of various source materials addressed in the literature. The review also provides insights into research gaps in the field to promote future research. 相似文献
23.
Automation and Remote Control - We consider multicriteria minimax optimization problems with criteria in the form of the maxima of functionals given by the induced norms of linear operators taking... 相似文献
24.
Viktoria M. S. Kjær Loukas Ieremias Dr. Viktorija Daugvilaite Dr. Michael Lückmann Prof. Thomas M. Frimurer Prof. Trond Ulven Prof. Mette M. Rosenkilde Dr. Jon Våbenø 《ChemMedChem》2021,16(17):2623-2627
The G protein-coupled receptor GPR183/EBI2, which is activated by oxysterols, is a therapeutic target for inflammatory and metabolic diseases where both antagonists and agonists are of potential interest. Using the piperazine diamide core of the known GPR183 antagonist (E)-3-(4-bromophenyl)-1-(4-(4-methoxybenzoyl)piperazin-1-yl)prop-2-en-1-one (NIBR189) as starting point, we identified and sourced 79 structurally related compounds that were commercially available. In vitro screening of this compound collection using a Ca2+ mobilization assay resulted in the identification of 10 compounds with agonist properties. To enable establishment of initial structure-activity relationship trends, these were supplemented with five in-house compounds, two of which were also shown to be GPR183 agonists. Taken together, our findings suggest that the agonist activity of this compound series is dictated by the substitution pattern of one of the two distal phenyl rings, which functions as a molecular efficacy-switch. 相似文献
25.
Gladson S. Chrisben Prasad P. Siva Manickam Bhaskar 《Analog Integrated Circuits and Signal Processing》2021,109(3):571-583
Analog Integrated Circuits and Signal Processing - As the 5G era beckons in the world of communication and information technology, there is a surge in demand for battery-operated, mobile wireless... 相似文献
26.
Dr. Thomas Le Bihan Dr. Cathryn H. S. Driver Dr. Thomas Ebenhan Dr. Nathalie Le Bris Dr. Jan Rijn Zeevaart Prof. Dr. Raphaël Tripier 《ChemMedChem》2021,16(5):809-821
An improved glucose-chelator-albumin bioconjugate (GluCAB) derivative, GluCAB-2Mal, has been synthesized and studied for in vivo 64Cu-PET/CT imaging in breast cancer mice models together with its first-generation analogue GluCAB-1Mal. The radioligand works on the principle of tumor targeting through the enhanced permeability and retention (EPR) effect with a supportive role played by glucose metabolism. [64Cu]Cu-GluCAB-2Mal (99 % RCP) exhibited high serum stability with immediate binding to serum proteins. In vivo experiments for comparison between tumor targeting of [64Cu]Cu-GluCAB-2Mal and previous-generation [64Cu]Cu-GluCAB-1Mal encompassed microPET/CT imaging and biodistribution analysis in an allograft E0771 breast cancer mouse model. Tumor uptake of [64Cu]Cu-GluCAB-2Mal was clearly evident with twice as much accumulation as compared to its predecessor and a tumor/muscle ratio of up to 5 after 24 h. Further comparison indicated a decrease in liver accumulation for [64Cu]Cu-Glu-CAB-2Mal. 相似文献
27.
Zhuchkov V. I. Nazansky S. L. Frolkova A. K. Ganina K. D. 《Theoretical Foundations of Chemical Engineering》2021,55(4):786-791
Theoretical Foundations of Chemical Engineering - Using gas–liquid chromatography, the activity coefficients upon the infinite dilution of the components of the reaction mixture for obtaining... 相似文献
28.
Chaozhong Sun Xiaoying Guo Rui Ji Changzheng Hu Laijun Liu Liang Fang Zhenxiang Cheng Nengneng Luo 《Ceramics International》2021,47(4):5038-5043
The triboelectric effect has recently demonstrated its great potential in environmental remediation and even new energy applications for triggering a number of catalytic reactions by utilizing trivial mechanical energy. In this study, Ba4Nd2Fe2Nb8O30 (BNFN) submicron powders were used to degrade organic dyes via the tribocatalytic effect. Under the frictional excitation of three PTFE stirring rods in a 5 mg/L RhB dye solution, BNFN demonstrates a high tribocatalytic degradation efficiency of 97% in 2 h. Hydroxyl radicals (?OH) and superoxide radicals (?O2-) were also detected during the catalysis process, which proves that triboelectric energy stimulates BNFN to generate electron-hole pairs. The tribocatalysis of tungsten bronze BNFN submicron powders provides a novel and efficient method for the degradation of wastewater dye by utilizing trivial mechanical energy. 相似文献
29.
Xiaojun Chen Hongyang Liu Dechao Hu Huaqing Liu Wenshi Ma 《Ceramics International》2021,47(17):23749-23761
With the blossom of information industry, electromagnetic wave technology shows increasingly potential in many fields. Nevertheless, the trouble caused by electromagnetic waves has also drawn extensive attention. For instance, electromagnetic pollution can threaten information safety in vital fields and the normal function of delicate electronic devices. Consequently, electromagnetic pollution and interference become an urgent issue that needs to be addressed. Carbon nanotubes (CNTs) have become a potential candidate to deal with these problems due to many advantages, such as high dielectric loss, remarkable thermodynamic stability, and low density. With the appearance of climbing demands, however, the carbon nanotubes combining various composites have shown greater prospects than the single CNTs in microwave absorbing materials. In this short review, recent advances in CNTs-based microwave absorbing materials were comprehensively discussed. Typically, we introduced the electromagnetic wave absorption mechanism of CNTs-based microwave absorbing materials and generalized the development of CNTs-based microwave absorbers, including CNTs-based magnetic metal composites, CNTs-based ferrite composites, and CNTs-based polymer composites. Ultimately, the growing trend and bottleneck of CNTs-based composites for microwave absorption were analyzed to provide some available ideas to more scientific workers. 相似文献
30.
Xiao-Mei Sha Li-Jun Zhang Wen-Mei Chen Guang-Yao Wang Jin-Lin Li Zi-Zi Hu Zong-Cai Tu 《International Journal of Food Science & Technology》2022,57(3):1573-1586
Thermal action in extraction process had effects on characteristic tryptic peptides identification and gelling properties of porcine gelatin. SDS-PAGE, HPLC-LTQ/Orbitrap high-resolution mass spectrometry, texture analyser and rheometer were used to evaluate collagen depolymerisation degree, characteristic tryptic peptides and gelling properties of gelatins prepared in various thermal actions. Results showed that with increasing temperature and time, depolymerisation degree enlarged, while gel strength, gelling and melting temperature decreased. Mass spectra showed that 47 and 49 common characteristic tryptic peptides were identified in gelatins extracted at 50 °C and 100 °C with various times, respectively. Moreover, 34 common characteristic tryptic peptides were identified in all gelatin samples. Further comparison between this work and our previous investigations yielded 20 common characteristic tryptic peptides, which stably exist in various thermal actions. These common characteristic tryptic peptides may be very helpful for the accurate authentication of porcine gelatin. 相似文献