全文获取类型
收费全文 | 20810篇 |
免费 | 2412篇 |
国内免费 | 935篇 |
专业分类
电工技术 | 1878篇 |
技术理论 | 1篇 |
综合类 | 1850篇 |
化学工业 | 1755篇 |
金属工艺 | 1461篇 |
机械仪表 | 2119篇 |
建筑科学 | 2607篇 |
矿业工程 | 721篇 |
能源动力 | 787篇 |
轻工业 | 1832篇 |
水利工程 | 492篇 |
石油天然气 | 901篇 |
武器工业 | 316篇 |
无线电 | 1304篇 |
一般工业技术 | 2509篇 |
冶金工业 | 1804篇 |
原子能技术 | 171篇 |
自动化技术 | 1649篇 |
出版年
2024年 | 558篇 |
2023年 | 545篇 |
2022年 | 815篇 |
2021年 | 873篇 |
2020年 | 810篇 |
2019年 | 590篇 |
2018年 | 566篇 |
2017年 | 691篇 |
2016年 | 764篇 |
2015年 | 753篇 |
2014年 | 1242篇 |
2013年 | 1209篇 |
2012年 | 1280篇 |
2011年 | 1492篇 |
2010年 | 1126篇 |
2009年 | 1135篇 |
2008年 | 1022篇 |
2007年 | 1200篇 |
2006年 | 1167篇 |
2005年 | 1062篇 |
2004年 | 891篇 |
2003年 | 780篇 |
2002年 | 688篇 |
2001年 | 596篇 |
2000年 | 443篇 |
1999年 | 374篇 |
1998年 | 270篇 |
1997年 | 260篇 |
1996年 | 225篇 |
1995年 | 159篇 |
1994年 | 131篇 |
1993年 | 94篇 |
1992年 | 57篇 |
1991年 | 47篇 |
1990年 | 42篇 |
1989年 | 37篇 |
1988年 | 29篇 |
1987年 | 22篇 |
1986年 | 13篇 |
1985年 | 12篇 |
1984年 | 12篇 |
1983年 | 14篇 |
1982年 | 9篇 |
1981年 | 5篇 |
1980年 | 8篇 |
1979年 | 4篇 |
1965年 | 4篇 |
1964年 | 5篇 |
1963年 | 3篇 |
1959年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
992.
993.
994.
结合新疆某大型渠道长距离冬季非冰盖输水发电运行实践,摸清冰情、冰害及对输水产生的影响,分析研究冬季输水存在的问题,探索冰期输水安全措施,确保渠道工程安全和冰期输水安全,为今后的冬季输水管理提供参考。 相似文献
995.
996.
运行多年的水工钢闸门都不同程度存在锈蚀现象,严重的锈蚀会导致水工钢闸门构件强度的降低,影响钢闸门的运行安全.如何对既有水工钢闸门进行合理鉴定,并估算其剩余寿命和可靠性是一个值得探讨的课题.主要采用数理统计理论的方法,结合工程实践,探索水工钢闸门结构在不同锈蚀条件下的剩余寿命估算方法,分析既有(包括超期服役)水工钢闸门剩余寿命的可靠性. 相似文献
997.
998.
Many new speciality polymers have been developed in the last few years. In this paper polymeric stabilizers (antioxidants, flame retardants and ultraviolet stabilizers) will be discussed. Polymeric antioxidants of the hindered-phenol type, copolymers of 2,6-ditertiarybutyl-4-vinyl(or isopropenyl)phenol with styrene, methyl methacrylate, or more importantly butadiene or isoprene have been prepared; hydrogenation of the latter copolymers gave copolymers of the two polymerizable phenolic antioxidants with ethylene or ethylene/propylene. The polymeric antioxidants have been blended with diene polymers and selected polyolefins and have improved the long-term oxidative stability of these polymers. Polymeric flame retardants have been prepared by copolymerizing styrene and/or acrylonitrile with acrylates and methacrylates of aliphatic bromine-containing alcohols or bromine-containing phenols. Polymers with polymer-bound flame retardants have a higher limiting oxygen index compared with the original polymer. A new class of polymerizable ultraviolet stabilizers has also been developed; these stabilizers are styryl, α-methylstyryl, acryloyl and methacryloyl derivatives of 2(2-hydroxyphenyl)2H-benzotriazoles. These monomers have been copolymerized with styrene, acrylates and methacrylates. 2(2-Hydroxyphenyl)2H-benzotriazoles substituted in the 4 position of the benzotriazole ring with hydroxyl, acetoxy or carboxyl groups suitable for incorporation into polyesters, polycarbonates, polyamides and epoxy resins have also been synthesized. All 2(2-hydroxyphenyl)2H-benzotriazole ultraviolet absorbers and the polymers into which they are incorporated have high light absorbency with γmax between 330 and 350 nm and extinction coefficients in some cases as high as 4.5 × 104 1 mol?1 cm?1. 相似文献
999.
David M. Barbano 《Journal of dairy science》2017,100(12):9894-9902
During the first 100 years of the Journal of Dairy Science, dairy foods and dairy production dairy scientists have partnered to publish new data and research results that have fostered the development of new knowledge. This knowledge has been the underpinning of both the commercial development of the fluid milk processing industry and regulations and marketing policies for the benefit of dairy farmers, processors, and consumers. During the first 50 years, most of the focus was on producing and delivering high-quality raw milk to factories and improving the shelf life of pasteurized fluid milk. During the second 50 years, raw milk quality was further improved through the use of milk quality payment incentives. Due to changing demographics and lifestyle, whole fluid milk consumption declined and processing technologies were developed to increase the range of fluid milk products (skim and low-fat milks, flavored milks, lactose-reduced milk, long-shelf-life milks, and milks with higher protein and calcium contents) offered to the consumer. In addition, technology to produce specialty high-protein sports beverages was developed, which expanded the milk-based beverage offerings to the consumer. 相似文献
1000.