全文获取类型
收费全文 | 269299篇 |
免费 | 5144篇 |
国内免费 | 1353篇 |
专业分类
电工技术 | 4751篇 |
综合类 | 744篇 |
化学工业 | 40441篇 |
金属工艺 | 8659篇 |
机械仪表 | 7921篇 |
建筑科学 | 7561篇 |
矿业工程 | 720篇 |
能源动力 | 7739篇 |
轻工业 | 30379篇 |
水利工程 | 2340篇 |
石油天然气 | 2012篇 |
武器工业 | 32篇 |
无线电 | 35434篇 |
一般工业技术 | 48504篇 |
冶金工业 | 49308篇 |
原子能技术 | 3500篇 |
自动化技术 | 25751篇 |
出版年
2022年 | 1351篇 |
2021年 | 2236篇 |
2020年 | 1598篇 |
2019年 | 1973篇 |
2018年 | 2919篇 |
2017年 | 2910篇 |
2016年 | 3236篇 |
2015年 | 2497篇 |
2014年 | 4131篇 |
2013年 | 12812篇 |
2012年 | 7435篇 |
2011年 | 10508篇 |
2010年 | 8084篇 |
2009年 | 9113篇 |
2008年 | 9620篇 |
2007年 | 9637篇 |
2006年 | 8890篇 |
2005年 | 8002篇 |
2004年 | 7815篇 |
2003年 | 7934篇 |
2002年 | 7682篇 |
2001年 | 7967篇 |
2000年 | 6845篇 |
1999年 | 7260篇 |
1998年 | 17399篇 |
1997年 | 12033篇 |
1996年 | 9077篇 |
1995年 | 6881篇 |
1994年 | 5956篇 |
1993年 | 5847篇 |
1992年 | 4150篇 |
1991年 | 3889篇 |
1990年 | 3657篇 |
1989年 | 3478篇 |
1988年 | 3388篇 |
1987年 | 2676篇 |
1986年 | 2579篇 |
1985年 | 3282篇 |
1984年 | 2868篇 |
1983年 | 2631篇 |
1982年 | 2417篇 |
1981年 | 2471篇 |
1980年 | 2279篇 |
1979年 | 2094篇 |
1978年 | 1920篇 |
1977年 | 2257篇 |
1976年 | 2897篇 |
1975年 | 1630篇 |
1974年 | 1516篇 |
1973年 | 1601篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
Tuladhar Sanira Alsadoon Abeer Prasad P. W. C. Ali Akbas Ezaldeen Alrubaie Ahmad 《Multimedia Tools and Applications》2022,81(17):23845-23865
Multimedia Tools and Applications - Gastrointestinal stromal tumor is one of the critical tumors that doctors do not suggest to get frequent endoscopy, so there is a need for a diagnosis system... 相似文献
22.
Deborah Oliveira De Fusco Leonardo Lucas Madaleno Vanildo Luiz Del Bianchi Aline da Silva Bernardo Rafael Roberto Assis Gustavo Henrique de Almeida Teixeira 《International Journal of Food Science & Technology》2019,54(7):2416-2424
Alcohol-free beer with isotonic properties is getting more popular and its production can be carried out by different production strategies; however, interrupted fermentation is still a challenge. Therefore, the objective of this study was to develop a low-alcohol isotonic beer (<0.5% v/v) by interrupted fermentation. Moreover, the major objective is to compare the developed product to commercial beverages (sports drinks, ‘Pilsen' regular beer, alcohol-free beers and low-alcohol isotonic beer). The beverages were evaluated based on pH, alcohol content (% v/v), total titratable acidity (mEq L−1), osmolality (mOsmol kg−1), bitterness International Bitterness Units, colour European Brewery Convention, total phenolic compounds (mg L−1 gallic acid), reducing and total sugars (%) and Na and K contents (mg L−1). The developed low-alcohol isotonic beer presented characteristics similar to sports drinks, with the advantage of being richer in phenolic compounds and suitable osmolality. Despite salts were added in its formulation, the grades attributed to all beers employed in the sensory evaluation, as well as the purchase intention did not present significant differences. 相似文献
23.
Norfariza Jamaluddin David C. Stuckey Arbakariya B. Ariff 《Critical reviews in food science and nutrition》2018,58(14):2453-2465
ABSTRACTBacteriocin is a proteinaceous biomolecule produced by bacteria (both Gram-positive and Gram-negative) that exhibits antimicrobial activity against closely related species, and food-borne pathogens. It has recently gained importance and attracted the attention of several researchers looking to produce it from various substrates and bacterial strains. This ushers in a new era of food preservation where the use of bacteriocin in food products will be an alternative to chemical preservatives, and heat treatment which are understood to cause unwanted side effects, and reduce sensory and nutritional quality. However, this new market depends on the success of novel downstream separation schemes from various types of crude feedstocks which are both effective and economic. This review focuses on the downstream separation of bacteriocin from various sources using both conventional and novel techniques. Finally, recommendations for future interesting areas of research that need to be pursued are highlighted. 相似文献
24.
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
25.
Kathryn C. Sole John Parker Peter M. Cole Michael B. Mooiman 《Mineral Processing and Extractive Metallurgy Review》2019,40(3):194-206
The price of cobalt has increased by some 450% in the past two years, mainly due to increasing demand for lithium–ion batteries. With an official 2017 production of 64 kt, the Democratic Republic of Congo produces more than half of the world’s cobalt. African Copperbelt operations have traditionally focused on copper production; however, it has now become imperative to also consider cobalt recovery from these ores. A plethora of processing routes is possible. Most hydrometallurgical flowsheets recover cobalt from the raffinate of the low-grade copper solvent-extraction circuit. Downstream purification processes include sequential precipitation with a variety of reagents, solvent extraction, and ion exchange. Product choices include hydroxide, carbonate, sulfate, and metal cathode. This study assesses technical and economic advantages and limitations of various approaches to the hydrometallurgical processing of cobalt in an African context. 相似文献
26.
Michael A. Clegg Prof. Nicholas C. O. Tomkinson Dr. Rab K. Prinjha Dr. Philip G. Humphreys 《ChemMedChem》2019,14(4):362-385
The bromodomain and extra terminal (BET) family of bromodomain-containing proteins (BCPs) have been the subject of extensive research over the past decade, resulting in a plethora of high-quality chemical probes for their tandem bromodomains. In turn, these chemical probes have helped reveal the profound biological role of the BET bromodomains and their role in disease, ultimately leading to a number of molecules in active clinical development. However, the BET subfamily represents just 8/61 of the known human bromodomains, and attention has now expanded to the biological role of the remaining 53 non-BET bromodomains. Rapid growth of this research area has been accompanied by a greater understanding of the requirements for an effective bromodomain chemical probe and has led to a number of new non-BET bromodomain chemical probes being developed. Advances since December 2015 are discussed, highlighting the strengths/caveats of each molecule, and the value they add toward validating the non-BET bromodomains as tractable therapeutic targets. 相似文献
27.
Photonic Network Communications - Optical packet switching is a prominent technology proposing not only a reduction in the energy consumption by the elimination of numerous... 相似文献
28.
29.
30.