全文获取类型
收费全文 | 30030篇 |
免费 | 1369篇 |
国内免费 | 132篇 |
专业分类
电工技术 | 490篇 |
综合类 | 235篇 |
化学工业 | 5111篇 |
金属工艺 | 799篇 |
机械仪表 | 671篇 |
建筑科学 | 806篇 |
矿业工程 | 152篇 |
能源动力 | 506篇 |
轻工业 | 4048篇 |
水利工程 | 217篇 |
石油天然气 | 136篇 |
武器工业 | 10篇 |
无线电 | 1610篇 |
一般工业技术 | 5461篇 |
冶金工业 | 7476篇 |
原子能技术 | 173篇 |
自动化技术 | 3630篇 |
出版年
2023年 | 309篇 |
2022年 | 276篇 |
2021年 | 628篇 |
2020年 | 517篇 |
2019年 | 448篇 |
2018年 | 919篇 |
2017年 | 830篇 |
2016年 | 917篇 |
2015年 | 821篇 |
2014年 | 958篇 |
2013年 | 1799篇 |
2012年 | 1378篇 |
2011年 | 1412篇 |
2010年 | 1188篇 |
2009年 | 1133篇 |
2008年 | 1280篇 |
2007年 | 1197篇 |
2006年 | 844篇 |
2005年 | 711篇 |
2004年 | 507篇 |
2003年 | 487篇 |
2002年 | 436篇 |
2001年 | 348篇 |
2000年 | 338篇 |
1999年 | 458篇 |
1998年 | 2308篇 |
1997年 | 1401篇 |
1996年 | 999篇 |
1995年 | 588篇 |
1994年 | 488篇 |
1993年 | 449篇 |
1992年 | 185篇 |
1991年 | 181篇 |
1990年 | 160篇 |
1989年 | 160篇 |
1988年 | 149篇 |
1987年 | 166篇 |
1986年 | 141篇 |
1985年 | 221篇 |
1984年 | 189篇 |
1983年 | 166篇 |
1982年 | 140篇 |
1981年 | 180篇 |
1980年 | 173篇 |
1979年 | 128篇 |
1978年 | 108篇 |
1977年 | 230篇 |
1976年 | 491篇 |
1975年 | 91篇 |
1973年 | 119篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
993.
Züliyet. Adigüzel Mustafa Anik 《Protection of Metals and Physical Chemistry of Surfaces》2018,54(2):316-324
Nickel (Ni)–Tungsten (W) alloys were electrodeposited galvanostatically (at–10 mA cm–2) on copper substrate with 3 different W contents under the controlled hydrodynamic conditions and then the anodic dissolution behaviors of the alloys were observed by potentiodynamic polarization and electrochemical quartz crystal microbalance (EQCM) techniques. While the structure of the electrodeposited Ni–W alloy with low W content (15.90% W) was crystalline, that of the alloy with high W content (50.80% W) was nano-crystalline according to X-ray diffraction patterns. The increase in the W content of the electrodeposited Ni–W alloy resulted decrease at pH 3 and increase at pH 7 and 12.5 in the anodic currents of the alloy. The pH dependent dissolutions caused electrodeposited alloy surface to have W—enrichment at pH 3 and Ni—enrichment at pH 7 and 12.5. These observations indicated that the selective dissolution of Ni or W was the main mechanism in the anodic dissolution of the electrodeposited Ni–W alloys. The EQCM experiments conducted at pH 7 supported the presence of the selective dissolution mechanism that the anodic dissolution potential of W was 0.42 V lower than that of Ni in the electrodeposited Ni–W alloys. 相似文献
994.
Minds and Machines - In this paper, we show that reproducibility is a severe problem that concerns simulation models. The reproducibility problem challenges the concept of numerical solution and... 相似文献
995.
Software and Systems Modeling - Engineers commonly use paper and whiteboards to sketch and discuss ideas in early phases of requirements elicitation and software modeling. These physical media... 相似文献
996.
In this paper, we analyse a systematically designed and easily tunable backstepping-based boundary control concept for a gantry crane with heavy chain and payload. The corresponding closed-loop system is formulated as an abstract evolution equation in an appropriate Hilbert space. Non-restrictive conditions for the controller coefficients are derived, under which the solutions are described by a C0-semi-group of contractions, and are asymptotically stable. Moreover, by applying Huang's theorem we can finally even show that under these conditions the controller renders the closed-loop system exponentially stable. 相似文献
997.
Thi Ngoc Trang Tran Müslüm Atas Alexander Felfernig Martin Stettinger 《Journal of Intelligent Information Systems》2018,50(3):501-526
Recently, food recommender systems have received increasing attention due to their relevance for healthy living. Most existing studies on the food domain focus on recommendations that suggest proper food items for individual users on the basis of considering their preferences or health problems. These systems also provide functionalities to keep track of nutritional consumption as well as to persuade users to change their eating behavior in positive ways. Also, group recommendation functionalities are very useful in the food domain, especially when a group of users wants to have a dinner together at home or have a birthday party in a restaurant. Such scenarios create many challenges for food recommender systems since the preferences of all group members have to be taken into account in an adequate fashion. In this paper, we present an overview of recommendation techniques for individuals and groups in the healthy food domain. In addition, we analyze the existing state-of-the-art in food recommender systems and discuss research challenges related to the development of future food recommendation technologies. 相似文献
998.
999.
F. Schnaid D. Winter A.E.F. Silva D. Alexiew V. Küster 《Geotextiles and Geomembranes》2017,45(3):227-236
Geosynthetic Encased Sand Columns (GEC) have been frequently adopted in geo-engineering practice to improve bearing capacity, reduce settlements and accelerate consolidation in saturated soft cohesive ground (e.g. Alexiew et al, 2005; Alexiew et al., 2012; Raithel et al, 2005). The present paper extends these early views by introducing the use of columns to reduce the magnitude of horizontal earth pressures acting on structures adjacent to compaction fills. The monitoring program of a full-scale bridge abutment on soft soil supported by GECs and geogrid reinforced system is described, where field performance is monitored with pressure cells, electrical piezometers, inclinometers and settlement plates. Analytical and numerical analyses have been performed to help on interpreting experimental measurements. The collected database is interpreted to demonstrate that GEC can reduce by up to 50% the horizontal earth pressure over bridge border foundation piles when compared to values predicted for unreinforced ground and demonstrate that the work conformed to acceptable limits of behavior. 相似文献
1000.
Industrial production systems and industrially manufactured products are constantly evolving due to technical innovations and customers’ demands. Therefore, ensuring an optimized co-evolution of both becomes an important yet challenging task. Approaches for model-based systems engineering have been widely investigated and have already had significant impact on industrial practice. However, existing model-based approaches mostly are focusing on particular aspects of a production system and do not provide a holistic approach for optimizing automated production systems, their deployment, and their co-evolution with the product. As a first step towards this direction, this contribution proposes the combination of an engineering approach for aPS based on systems modeling language with models and techniques for deployment of software and hardware to cyber-physical system architectures, which have been investigated in the field of computer science, and motivates the possibilities of a combined approach. 相似文献