全文获取类型
收费全文 | 37189篇 |
免费 | 3904篇 |
国内免费 | 2149篇 |
专业分类
电工技术 | 2404篇 |
技术理论 | 3篇 |
综合类 | 3176篇 |
化学工业 | 6021篇 |
金属工艺 | 2144篇 |
机械仪表 | 2390篇 |
建筑科学 | 2764篇 |
矿业工程 | 1340篇 |
能源动力 | 1128篇 |
轻工业 | 2870篇 |
水利工程 | 743篇 |
石油天然气 | 1605篇 |
武器工业 | 296篇 |
无线电 | 4271篇 |
一般工业技术 | 4511篇 |
冶金工业 | 1802篇 |
原子能技术 | 466篇 |
自动化技术 | 5308篇 |
出版年
2024年 | 161篇 |
2023年 | 599篇 |
2022年 | 1055篇 |
2021年 | 1489篇 |
2020年 | 1148篇 |
2019年 | 1033篇 |
2018年 | 1110篇 |
2017年 | 1221篇 |
2016年 | 1145篇 |
2015年 | 1552篇 |
2014年 | 1902篇 |
2013年 | 2354篇 |
2012年 | 2459篇 |
2011年 | 2473篇 |
2010年 | 2345篇 |
2009年 | 2140篇 |
2008年 | 2101篇 |
2007年 | 1946篇 |
2006年 | 1929篇 |
2005年 | 1668篇 |
2004年 | 1280篇 |
2003年 | 1510篇 |
2002年 | 2002篇 |
2001年 | 1750篇 |
2000年 | 1089篇 |
1999年 | 860篇 |
1998年 | 560篇 |
1997年 | 456篇 |
1996年 | 373篇 |
1995年 | 344篇 |
1994年 | 271篇 |
1993年 | 176篇 |
1992年 | 165篇 |
1991年 | 143篇 |
1990年 | 91篇 |
1989年 | 78篇 |
1988年 | 62篇 |
1987年 | 35篇 |
1986年 | 29篇 |
1985年 | 22篇 |
1984年 | 13篇 |
1983年 | 6篇 |
1982年 | 15篇 |
1981年 | 9篇 |
1980年 | 23篇 |
1979年 | 9篇 |
1978年 | 5篇 |
1977年 | 6篇 |
1959年 | 6篇 |
1951年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
21.
22.
23.
This study assessed the collection efficiency (CE) of two popularly used sampling devices (BioSampler and Coriolis sampler) for fungal aerosols. Phosphate‐buffered saline (PBS) supplemented with or without surfactant (Tween‐20, Tween‐80, or Triton X‐100) and antifoam agent was prepared and used as collection liquids. The agar impactor (BioStage) was simultaneously operated with liquid‐based samplers to collect fungi from seven sites located at a university building, public library, and animal farming. Fungal concentrations determined by liquid samplers were divided by those by BioStage, and the ratio values represented CE. Results indicate that the CE of BioSampler was superior to that of Coriolis (P = 0.0001) and the PBS containing surfactant collected fungi better than that without surfactant (P < 0.0001), whereas antifoam agent showed no influence (P = 0.8). Moreover, fungal concentrations determined by BioSampler with surfactant‐added PBS were statistically indifferent from those by BioStage (P > 0.05) with a Spearman correlation coefficient of 0.81‐0.83 (P < 0.01). In addition to sampler and collection liquid, sampling location was also identified as a significant CE factor (P = 0.006), implying potential influences by fungal genera in the studied fields. Overall, BioSampler with surfactant‐supplemented PBS (eg, Triton X‐100) is recommended considering the great CE and compatibility with a variety of analytical assays. 相似文献
24.
A novel dual-rotation bobbin tool friction stir welding (DBT-FSW) was developed, in which the upper shoulder (US) and lower shoulder (LS) have different rotational speeds. This process was tried to weld 3.2 mm thick aluminum-lithium alloy sheets. The metallographic analysis and torque measurement were carried out to characterize the weld formability. Experimental results show that compared to conventional bobbin tool friction stir welding, the DBT-FSW has an excellent process stability, and can produce the defect-free joints in a wider range of welding parameters. These can be attributed to the significant improvement of material flow caused by the formation of a staggered layer structure and the unbalanced force between the US and LS during the DBT-FSW process. 相似文献
26.
Microsystem Technologies - Recently, nonlinear system identification has received increasingly more attention due to its promising applications in engineering fields. It has become a challenging... 相似文献
27.
28.
燕皮传统加工工艺中碱液对肉糜特性的影响 总被引:1,自引:1,他引:0
燕皮是以猪肉和甘薯粉为原料,手工制成的薄如纸且经煮不烂的传统食品。在传统制作燕皮过程中添加山榉灰配制的碱液是影响肉糜品质的关键步骤。通过测定制作燕皮过程中各工序样品的氮溶解指数、持水性、乳化稳定性、pH值和粘度,利用SDS-PAGE分析样品中的蛋白质组分、利用光学显微镜观察它们的结构变化,证实植物碱液能够提高样品的氮溶解指数、持水性和乳化稳定性并且延迟了肉糜硬化。同时实验证明碳酸碱(Na2CO3或K2CO3)可替代传统工艺中的植物碱,为后续标准化、工业化生产提供可行条件。 相似文献
29.
30.