全文获取类型
收费全文 | 24516篇 |
免费 | 2245篇 |
国内免费 | 1206篇 |
专业分类
电工技术 | 874篇 |
技术理论 | 4篇 |
综合类 | 2911篇 |
化学工业 | 1538篇 |
金属工艺 | 504篇 |
机械仪表 | 795篇 |
建筑科学 | 6272篇 |
矿业工程 | 1239篇 |
能源动力 | 609篇 |
轻工业 | 1032篇 |
水利工程 | 1647篇 |
石油天然气 | 777篇 |
武器工业 | 252篇 |
无线电 | 1466篇 |
一般工业技术 | 1549篇 |
冶金工业 | 1976篇 |
原子能技术 | 168篇 |
自动化技术 | 4354篇 |
出版年
2024年 | 72篇 |
2023年 | 349篇 |
2022年 | 669篇 |
2021年 | 771篇 |
2020年 | 718篇 |
2019年 | 597篇 |
2018年 | 482篇 |
2017年 | 647篇 |
2016年 | 727篇 |
2015年 | 806篇 |
2014年 | 1445篇 |
2013年 | 1289篇 |
2012年 | 1433篇 |
2011年 | 1833篇 |
2010年 | 1516篇 |
2009年 | 1649篇 |
2008年 | 1558篇 |
2007年 | 1837篇 |
2006年 | 1647篇 |
2005年 | 1376篇 |
2004年 | 1206篇 |
2003年 | 1058篇 |
2002年 | 929篇 |
2001年 | 733篇 |
2000年 | 547篇 |
1999年 | 431篇 |
1998年 | 299篇 |
1997年 | 229篇 |
1996年 | 190篇 |
1995年 | 136篇 |
1994年 | 120篇 |
1993年 | 101篇 |
1992年 | 77篇 |
1991年 | 49篇 |
1990年 | 47篇 |
1989年 | 33篇 |
1988年 | 36篇 |
1987年 | 17篇 |
1986年 | 12篇 |
1985年 | 23篇 |
1984年 | 17篇 |
1983年 | 18篇 |
1964年 | 23篇 |
1963年 | 22篇 |
1961年 | 13篇 |
1960年 | 16篇 |
1959年 | 18篇 |
1958年 | 11篇 |
1957年 | 14篇 |
1955年 | 18篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
1.
《Ceramics International》2022,48(12):16808-16812
Flash sintering has been reported in various ceramics. Nevertheless, anion and cation conductors exhibit different flash-sintering behaviors, and the interaction mechanism between the conductive species and the sintering environment has remained unclear. Herein, we report the flash-sintering phenomena of a typical cation conductor, Na3Zr2(SiO4)2(PO4) with anode region surrounded by air and NaNO3 environments. The results prove that the ionic behavior and joule heating distribution can be controlled by changing the electrode environment. Four possible scenarios describing the ion migration behavior and interaction with the environment are proposed for providing a guidance for controlling the ion interaction behavior during flash sintering. 相似文献
2.
《International Journal of Hydrogen Energy》2022,47(3):2040-2049
The motion trajectory of hydrogen leakage is an essential safe issue for the application of hydrogen energy. A dimensionless fast-running motion trajectory prediction model is proposed to predict the dispersion characteristics of the buoyant jet of hydrogen leakage for the accident. The impact of different leakage angles, leakage velocity and thermal stratification of ambient air on hydrogen leakage behavior was analyzed. The new developed model was verified by experimental results in literatures. Leakage hydrogen can flow upwards freely in a uniform environment. However, it shows an oscillating trajectory at a certain height in a thermally stratified environment, which is so called “locking phenomenon”. The trajectory of hydrogen leakage is upward and hydrogen gathers at the top of the space to form stratification in a uniform environment, while the hydrogen leakage shows an oscillating trajectory at a certain height in a thermal stratification environment. With the increase of Froude number Fr, it shows that the stable height and maximum height of the leakage airflow have a trend of rising first and then falling in a thermally stratified environment. The findings are expected to give guidance in real-world situations, for example, a larger Fr value and a larger temperature gradient can lead to a decrease in the stable height in the thermally stratified environment. It is found that the fitting of the stable height with different temperature gradients satisfies the power function relationship. This work is expected to be helpful for reducing hydrogen leakage accumulation and explosion risk. 相似文献
3.
4.
5.
The effect of the emergency perception of bystanders of cyberbullying victims on helping behaviors is often neglected in research on cyberbullying. In this study, we explored the influence of this cognitive factor on cyber-bystanders’ helping tendencies as well as elucidated possible underlying processes. The results of two studies were reported. In Study 1, 150 undergraduates read a true case of a girl experiencing cyberbullying. The results indicated that when the participants perceived the victim’s situation to be more critical (i.e., higher emergency perception), their helping tendencies were stronger, partly through increased state empathy followed by feelings of responsibility to help. In Study 2, we randomly assigned 300 undergraduates to two groups. The low emergency group read the same cyberbullying case as Study 1, whereas the cyberbullying case read by the high emergency group contained additional emergency information of the victim. The results indicated that the high emergency group expressed stronger helping tendencies than did the low emergency group. This effect was caused by a stronger perception that the victim was in an emergency situation, which not only strengthened the participants’ helping tendencies directly but also indirectly through increasing their state empathy and feelings of responsibility to help. 相似文献
6.
In recent years, artificial intelligence (AI) is being increasingly utilised in disaster management activities. The public is engaged with AI in various ways in these activities. For instance, crowdsourcing applications developed for disaster management to handle the tasks of collecting data through social media platforms, and increasing disaster awareness through serious gaming applications. Nonetheless, there are limited empirical investigations and understanding on public perceptions concerning AI for disaster management. Bridging this knowledge gap is the justification for this paper. The methodological approach adopted involved: Initially, collecting data through an online survey from residents (n = 605) of three major Australian cities; Then, analysis of the data using statistical modelling. The analysis results revealed that: (a) Younger generations have a greater appreciation of opportunities created by AI-driven applications for disaster management; (b) People with tertiary education have a greater understanding of the benefits of AI in managing the pre- and post-disaster phases, and; (c) Public sector administrative and safety workers, who play a vital role in managing disasters, place a greater value on the contributions by AI in disaster management. The study advocates relevant authorities to consider public perceptions in their efforts in integrating AI in disaster management. 相似文献
7.
8.
价值观的传播是一个缓慢的过程,在当前工业文明向生态文明过渡的时期,如何有效地提升民众的生态意识是值得探讨的问题。以生态审美意识传播为切入点,通过了解国内外主流的室内环境生态评估指标体系的前后变化,总结当前室内环境生态评估的变化趋势及其主要特征;从指标体系的变化中分析生态审美价值观的渗透方式,探讨当代室内环境生态评估对生态审美价值观传播的促进作用。最后,通过实验设定针对室内传统营造技艺应用的评估工具,并且在评估工具的使用过程中展示传播的模式与效用,通过评估反馈再一次验证室内环境生态评估对生态审美价值观的正向传播作用。 相似文献
9.
10.
Acknowledging the lack of studies examining both visual and linguistic anthropomorphic cues and the underlying mechanisms of their effects, we investigated how the different modalities of anthropomorphic cues in a health website influenced information disclosure. In a 2 (visual cues: human vs. non-human image) × 2 (linguistic cues: conversational vs. impersonal language) × 2 (question type: less vs. more sensitive questions) between-subjects experiment (N = 254), participants registered with a mock-up health website. We assessed a behavioral outcome of not disclosing personal information and psychological outcomes of social perception and self-awareness as potential mediators. Results revealed distinctive effects of the two modalities of the anthropomorphic cues. Anthropomorphic images, on one hand, increased public and private self-awareness, and public self-awareness in turn led to less information disclosure. Anthropomorphic language, on the other hand, heightened social perception and promoted information disclosure, but social perception did not predict the disclosure. These results indicate unique underlying mechanisms of the effects of anthropomorphism: priming effect of visual cues, and communicative effects of linguistic cues. 相似文献