全文获取类型
收费全文 | 64117篇 |
免费 | 8016篇 |
国内免费 | 4795篇 |
专业分类
电工技术 | 6253篇 |
技术理论 | 1篇 |
综合类 | 5456篇 |
化学工业 | 8777篇 |
金属工艺 | 4107篇 |
机械仪表 | 4213篇 |
建筑科学 | 4919篇 |
矿业工程 | 2368篇 |
能源动力 | 1782篇 |
轻工业 | 5305篇 |
水利工程 | 2071篇 |
石油天然气 | 2965篇 |
武器工业 | 949篇 |
无线电 | 8087篇 |
一般工业技术 | 6640篇 |
冶金工业 | 2344篇 |
原子能技术 | 704篇 |
自动化技术 | 9987篇 |
出版年
2024年 | 494篇 |
2023年 | 1618篇 |
2022年 | 3273篇 |
2021年 | 4322篇 |
2020年 | 3045篇 |
2019年 | 2231篇 |
2018年 | 2255篇 |
2017年 | 2536篇 |
2016年 | 2267篇 |
2015年 | 3203篇 |
2014年 | 3816篇 |
2013年 | 4336篇 |
2012年 | 5174篇 |
2011年 | 5248篇 |
2010年 | 4559篇 |
2009年 | 4322篇 |
2008年 | 4284篇 |
2007年 | 4060篇 |
2006年 | 3485篇 |
2005年 | 2914篇 |
2004年 | 1901篇 |
2003年 | 1373篇 |
2002年 | 1268篇 |
2001年 | 1115篇 |
2000年 | 973篇 |
1999年 | 691篇 |
1998年 | 420篇 |
1997年 | 349篇 |
1996年 | 314篇 |
1995年 | 247篇 |
1994年 | 213篇 |
1993年 | 128篇 |
1992年 | 106篇 |
1991年 | 84篇 |
1990年 | 64篇 |
1989年 | 49篇 |
1988年 | 34篇 |
1987年 | 29篇 |
1986年 | 32篇 |
1985年 | 13篇 |
1984年 | 11篇 |
1983年 | 3篇 |
1982年 | 11篇 |
1981年 | 8篇 |
1980年 | 14篇 |
1979年 | 12篇 |
1975年 | 1篇 |
1973年 | 1篇 |
1959年 | 10篇 |
1951年 | 11篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
New parameters, light transmission rate and minimum light transmissions, are proposed. These two parameters reflect the characteristics of the membrane‐forming system and the formation process of the membranes by phase inversion. The relationship between the light transmission and the porous structure of the membrane can be explained by the geometrical optics principles. Variation of the two parameters combining Reuvers's phase separation theory provided a convenient analytical method to predict effectively membrane morphologies. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 174–181, 2003 相似文献
22.
Hao Liang Zhiqiang Zheng Zengchang Li Jie Xu Biao Chen Hui Zhao Qijin Zhang Hai Ming 《应用聚合物科学杂志》2004,93(2):681-685
A step‐index polymer optical fiber (SI POF) containing Rhodamine B in poly(methyl methacrylate) (PMMA) has been fabricated by a preform technique. Fluorescence of different fiber lengths were observed and discussed. A high gain (23 dB) for a SI POF with 60‐cm length, 400‐μm diameter was obtained. The Rhodamine B content of the doped SI POF is 5 ppm‐wt. The signal wavelength providing the highest gain for a 60 cm SI POF is around 630 nm, and the optimum fiber length is about 60 cm at 10 kW launched pump power. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 681–685, 2004 相似文献
23.
干法/半干法脱硫因占地小、投资小、费用低,能达到中等程度的脱硫效率而受到关注。脱硫剂影响脱硫效率的重要因素,Ca(OH)2作为一种优良的脱硫吸附剂,早已受到人们的重视。本文以比表面积为参数评价脱硫剂性能的优劣,研究选择制备高效脱硫剂的工艺方法。 相似文献
24.
气体控制参数对气体辅助成型产品翘曲的影响 总被引:2,自引:0,他引:2
从气体辅助注射成型工艺的角度探讨了气体的延迟时间和第一段压力这两个关键的参数对槽的影响进而对产品翘曲变形的影响,结果表明:虽然通过使用气体辅助注射成型技术能改善产品变形,但并不能完全消除变形;造成产品变形的原因和机理十分复杂,只有进行从设计到工艺的全方位考察才能有效的控制变形,气体手指效应也是造成产品变形的一个重要因素,工艺上可以通过调整延迟时间和气体压力来减小产品的变形量。 相似文献
25.
26.
The HUB-CI model is investigated in a telerobotic system in a client/server network to manage the lifecycle of engineering design and prototyping. The purpose of this platform is to support collaborative engineering design and proof of concept to enhance distributed team collaboration and resource utilization. The suggested platform is exemplified in two collaboration support tools and a physical prototyping platform. Structured Co-Insight Management is developed to support innovative idea exchanges and the consensus decision-making during the design process. Conflict/error detection management helps preventing conflicts and errors during the lifecycle of design and development. Physical collaboration over the network occurs when a team controls the telerobot operation during prototyping and testing in design cycles. A pilot system is implemented with a group project for the design of an electronic circuit (including both hardware and software designs). The functional assessment method is used to compare this platform to other collaborative design tools. The system presented offers unique qualitative advantages as an integrated collaboration support system. 相似文献
27.
28.
29.
Three-dimensionally ordered long-range macroporous carbon structures were prepared using commercially available phenolic resin
by utilizing sacrificial colloidal silica crystalline arrays as templates that were subsequently removed by HF etching after
pyrolysis in an argon atmosphere. SEM, TEM, and BET were employed to characterize the morphology and the surface area of the
porous carbon structures. The pore size (150–1000 nm) and BET surface area, which reflect pore volume (298.6 m2/g (1.32 cm3/g) ∼ 93.7 m2/g (0.12 cm3/g)), of the macroporous carbon structures produced were approximately proportional to the size (150–1000 nm) of the sacrificial
silica sphere templates used (annealing temp. 550°C). The achieved 550 nm porous carbon structures were examined to function
as potential catalyst carriers and were successfully impregnated with Ag or Pt-Ru on their inner walls after borohydride reduction
at room temperature. In addition, porous carbon patterns were fabricated using the ‘micromolding in capillary’ technique,
which has potential applications in the microreaction technology. 相似文献
30.
心理资本前因变量研究 总被引:5,自引:0,他引:5
郝明亮 《重庆科技学院学报(社会科学版)》2010,(11):93-95
采用心理资本问卷对分别属于医药、建筑、水利工程、电信、通讯运营和服务行业的6家企业的员工进行了调查.根据对回收的283份有效问卷的统计分析,认为员工的性别、受教育程度和所在企业的性质对员工心理资本不会产生显著性影响,而员工年龄的影响显著,50岁以上员工的总体心理资本水平高于其他年龄段员工. 相似文献