全文获取类型
收费全文 | 2441篇 |
免费 | 141篇 |
国内免费 | 15篇 |
学科分类
工业技术 | 2597篇 |
出版年
2024年 | 4篇 |
2023年 | 54篇 |
2022年 | 88篇 |
2021年 | 117篇 |
2020年 | 115篇 |
2019年 | 109篇 |
2018年 | 134篇 |
2017年 | 101篇 |
2016年 | 144篇 |
2015年 | 73篇 |
2014年 | 100篇 |
2013年 | 142篇 |
2012年 | 119篇 |
2011年 | 137篇 |
2010年 | 114篇 |
2009年 | 112篇 |
2008年 | 75篇 |
2007年 | 98篇 |
2006年 | 67篇 |
2005年 | 54篇 |
2004年 | 52篇 |
2003年 | 51篇 |
2002年 | 45篇 |
2001年 | 37篇 |
2000年 | 34篇 |
1999年 | 36篇 |
1998年 | 65篇 |
1997年 | 53篇 |
1996年 | 34篇 |
1995年 | 27篇 |
1994年 | 27篇 |
1993年 | 36篇 |
1992年 | 24篇 |
1991年 | 12篇 |
1990年 | 16篇 |
1989年 | 9篇 |
1988年 | 8篇 |
1987年 | 4篇 |
1986年 | 11篇 |
1985年 | 10篇 |
1984年 | 9篇 |
1983年 | 4篇 |
1982年 | 6篇 |
1981年 | 2篇 |
1978年 | 2篇 |
1977年 | 10篇 |
1976年 | 3篇 |
1975年 | 4篇 |
1973年 | 2篇 |
1965年 | 1篇 |
排序方式: 共有2597条查询结果,搜索用时 15 毫秒
81.
82.
Toan Dinh Van Dau Canh‐Dung Tran Tuan‐Khoa Nguyen Hoang‐Phuong Phan Nam‐Trung Nguyen Dzung Viet Dao 《大分子材料与工程》2019,304(6)
Flexible multifunctional electronic devices are of high interest for a wide range of applications including thermal therapy and respiratory devices in medical treatment, safety equipment, and structural health monitoring systems. This paper reports a scalable and efficient strategy of manufacturing a polyacrylonitrile‐carbon nanotube‐polyacrylonitrile (PAN‐CNT‐PAN) robust flexible platform for multifunctional electronic devices including flexible heaters, temperature sensors, and flexible thermal flow sensors. The key advantages of this platform include low cost, porosity, mechanical robustness, and electrical stability under mechanical bending, enabling the development of fast‐response flexible heaters with a response time of ≈1.5 s and relaxation time of ≈1.7 s. The temperature‐sensing functionality is also investigated with a range of temperature coefficient of resistances from ?650 to ?900 ppm K?1. A flexible hot‐film sensing concept is successfully demonstrated using PAN‐CNT‐PAN with a high sensitivity of 340 mV (m s?1)?1. The sensitivity enhancement of 50% W?1 is also observed with increasing supply power. The low cost, porosity, versatile, and robust properties of the proposed platform will enable the development of multifunctional electronic devices for numerous applications such as flexible thermal management, temperature stabilization in industrial processing, temperature sensing, and flexible/wearable devices for human healthcare applications. 相似文献
83.
Anna Haliaková Anna Prnová Róbert Klement Dušan Galusek Wei-Hsing Tuan 《Ceramics International》2012,38(7):5543-5549
The paper deals with the synthesis and characterisation of binary aluminate glasses in the La2O3–Al2O3 system with Al2O3 contents changing between 74.6 and 86.9 mol% (48–65 wt.%), and of ternary glasses with 75.7 mol% Al2O3 doped with 1 mol% of Nd2O3 or Er2O3. Six binary and two ternary compositions were prepared. Flame synthesis facilitated the preparation of X-ray amorphous microspheres in the systems with 58 wt.% Al2O3, and with eutectic composition in the pseudobinary LaAlO3–LaAl11O18 system doped with Er. Other systems contained low fractions of crystalline LaAlO3 perovskite, regardless of the composition. The diameter of prepared microspheres ranged between 2 and 10 μm. They were transparent for visible light, as well as in the IR wavenumber range from 1300 to 4000 cm?1. 相似文献
84.
Sai Wang Bang‐Ke Luo Ying‐Jun Qin Lin‐Hui Su Simon D. Stewart Tuan‐Tuan Wang Jin‐Peng Tang Bai‐Dong He Jin‐Hua Zhang Hsing‐Juh Lin Yang Yang 《河流研究与利用》2020,36(7):1124-1136
Understanding the trophic discrimination (?13C and ?15N) between consumers and diets in fluvial systems remains difficult because of the variable food sources and complex predator–prey interactions from headwaters to the estuaries. Here, stable carbon (δ13C) and nitrogen (δ15N) isotopes in fish and invertebrates from a large subtropical river in southern China were determined to explore trophic discrimination in conjunction with a gut content analysis. The ?13C values showed significant differences (p < .05) among functional feeding groups, with fish, shrimp, and insect scrapers presenting higher ?13C values (1.20 ± 0.23‰ to 1.51 ± 0.31‰) than other groups. The ?15N values varied significantly between invertebrates (0.64 ± 0.17‰ of insect collector‐gatherers to 1.63 ± 0.36‰ of shrimp predators) and fish (1.98 ± 0.19‰ of detritivores to 2.71 ± 0.43‰ of crustaceavores) and exhibited an increasing tendency from primary to secondary consumers. A linear regression analysis revealed that the longitudinal changes in ?13C and ?15N were closely associated with the δ13C of periphyton, the δ15N of particulate organic matter (POM) in water, and the relative contribution (%) of periphyton and organic detritus to the diet composition of consumers. These results indicated that discrimination factors might not only be influenced by the isotope signatures of basal food sources but also downstream shifts in dominant food items utilized by consumers. In particular, trophic discrimination between periphyton– and detritus–based food chains, such as “epilithic diatoms–shrimp scrapers–crustaceavorous fish” and “POM–bivalves–molluscivorous fish,” displayed regionally specific patterns. When back‐calculating to the diet assimilation and trophic position in subtropical streams and rivers, we suggest using the basin‐scale ?13C value of 0.96 ± 0.26‰ for all consumers and ?15N values of 1.07 ± 0.32‰ for invertebrates and 2.38 ± 0.37‰ for fish. 相似文献
85.
Sanghee Lee Theresa R. Mendoza Danielle N. Burner Michelle T. Muldong Christina C. N. Wu Catalina Arreola-Villanueva Abril Zuniga Olga Greenburg William Y. Zhu Jamillah Murtadha Evodie Koutouan Naomi Pineda Hao Pham Sung-Gu Kang Hyun Tae Kim Gabriel Pineda Kathleen M. Lennon Nicholas A. Cacalano Catriona H. M. Jamieson Christopher J. Kane Anna A. Kulidjian Terry Gaasterland Christina A. M. Jamieson 《International journal of molecular sciences》2022,23(6)
86.
Hoang V. Le Phuong T. Pham Ly T. Le Anh D. Nguyen Ngoc Quang Tran Phong D. Tran 《International Journal of Hydrogen Energy》2021,46(44):22852-22863
WO3 is a potential material candidate for construction of photoanode for solar driven water splitting. In this work, μm-thick porous WO3 photoanode is prepared by depositing a stable ink made of WO3 nanoparticles and Aristoflex velvet polymer in water using the doctor blade technique, followed by a sintering in air. The nature of WO3 nanoparticles, its loading mass on F-doped tin oxide electrode as well as sintering temperature are examined in order to optimize the photocatalytic activity of the resultant WO3 photoanode. The operation of WO3 photoanode is investigated by varying the light illumination direction and light incident intensity as well as changing the nature of the electrolyte. Dissolved tungsten in electrolyte is quantified by ICP-MS providing insights into the influences of electrolyte nature and operating conditions to the corrosion of WO3. It is proposed that the H2O2 and OH. radical generated as by-products of the photo-driven water oxidation on the photoanode surface are harmful species that accelerate the dissolution of WO3. 相似文献
87.
Minh-Tuan Pham Laurent Briançon Daniel Dias Abdelkader Abdelouhab 《Geotextiles and Geomembranes》2018,46(5):611-624
Geosynthetic-reinforced soils constitute an interesting solution for bridging cavities. Many methods have been developed to analyze the stability of soil-geosynthetic-cavity systems, but none of them is able to take into account all the complexities of these mechanisms. Many researchers have assumed mechanisms developed in the reinforced granular platform when cavities appear, such as load transfer and expansion of materials. However, they are not fully understood because many factors can influence the design, such as the cavity opening processes, the type, and the density of the soil.In this study, a new laboratory apparatus is developed to simulate two different cavity opening procedures (trapdoor and progressive opening) for different geometric configurations. A series of tests is conducted for three granular soils with two different geosynthetic sheets. By measuring the shape of the surface soil settlement and the geosynthetic deflection, the expansion coefficient is calculated. A novel tactile pressure sensor is used to observe the load transfer during the cavity opening. The experimental data are analyzed and the influence of the experimental conditions (geometric and soil properties and the opening procedure) are also discussed. Correspondingly, elicited findings can be used to propose recommendations to improve the existing design methods. 相似文献
88.
Phan Huy Hoang Anh Tuan Hoang Nguyen Hoang Chung Le Quang Dien Xuan Phuong Nguyen Xuan Duong Pham 《Energy Sources, Part A: Recovery, Utilization, and Environmental Effects》2018,40(3):312-319
In this study, new and efficient sorbent with density 0.2 g/cm3 was fabricated by incorporating rice straw into polyurethane matrix to get an open cell structure material with high oil uptake capacity. The influences of various important factors such as amount of adding rice straw, size of rice straw particles, and adsorption time on oil adsorption capacity of new sorbent material were investigated. The results showed that the oil absorption rate occurred fast in first 15–30 min, then slowed down and reached saturation level after about 2 h of treatment. Oil adsorption capacity of the new sorbent material was relatively high, up to 12.0 g/g. In comparison with pristine polyurethane or lignocellulosic materials, the new sorbents had higher oil adsorption capacity. Some characteristics of the as-obtained sorbent, such as surface shapes and porosity, were also studied by SEM analysis. 相似文献
89.
Pham Thanh Hue 《西部皮革》2018,(16)
越南太原省大慈县文安乡位于三岛国家公园管理处,社区居民生活困难,收入低,所以目前森林资源侵害状况依然存在。其中,25-50岁的群人对森林资源的影响最大,50岁以上和16岁以下的群人对森林资源的影响较小。人们对森林资源的影响是:伐木,狩猎动物,收集柴火,收集蔬菜,收集竹笋、药用植物。统计结果表明,天然林中具有18种树木经常被开发利用,常用木柴12种,药用29种,食用17种。7种动物经常被猎食。这些影响使得森林结构相当大改变,生物多样性减少,森林结构破坏。造成这种情况的主要原因是人们意识不高,缺乏工作机会,缺乏耕种土地,农业生产没有满足用户的需求。因此,必要有有关部门的协调在违法森林法的处理,为人民改善物质和精神生活,教育宣传和提高执法的认识 相似文献
90.
Wireless Personal Communications - Cognitive radio networks (CRNs) have a shortcoming in that attackers can increase their ability to disturb secondary users (SUs). This paper focuses on jamming... 相似文献