全文获取类型
收费全文 | 22929篇 |
免费 | 1889篇 |
国内免费 | 1076篇 |
专业分类
电工技术 | 1190篇 |
技术理论 | 4篇 |
综合类 | 1555篇 |
化学工业 | 4256篇 |
金属工艺 | 1447篇 |
机械仪表 | 1324篇 |
建筑科学 | 1774篇 |
矿业工程 | 596篇 |
能源动力 | 571篇 |
轻工业 | 1422篇 |
水利工程 | 388篇 |
石油天然气 | 1431篇 |
武器工业 | 143篇 |
无线电 | 2554篇 |
一般工业技术 | 2870篇 |
冶金工业 | 1100篇 |
原子能技术 | 232篇 |
自动化技术 | 3037篇 |
出版年
2024年 | 110篇 |
2023年 | 423篇 |
2022年 | 636篇 |
2021年 | 917篇 |
2020年 | 710篇 |
2019年 | 602篇 |
2018年 | 636篇 |
2017年 | 744篇 |
2016年 | 616篇 |
2015年 | 849篇 |
2014年 | 1046篇 |
2013年 | 1297篇 |
2012年 | 1388篇 |
2011年 | 1455篇 |
2010年 | 1343篇 |
2009年 | 1333篇 |
2008年 | 1246篇 |
2007年 | 1211篇 |
2006年 | 1202篇 |
2005年 | 1083篇 |
2004年 | 762篇 |
2003年 | 727篇 |
2002年 | 750篇 |
2001年 | 591篇 |
2000年 | 580篇 |
1999年 | 702篇 |
1998年 | 542篇 |
1997年 | 441篇 |
1996年 | 410篇 |
1995年 | 370篇 |
1994年 | 311篇 |
1993年 | 211篇 |
1992年 | 170篇 |
1991年 | 134篇 |
1990年 | 81篇 |
1989年 | 103篇 |
1988年 | 57篇 |
1987年 | 32篇 |
1986年 | 19篇 |
1985年 | 16篇 |
1984年 | 13篇 |
1983年 | 5篇 |
1982年 | 6篇 |
1981年 | 8篇 |
1980年 | 5篇 |
1979年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
The rapid growth of Chinese economy has tremendously stimulated the expansion of energy consumption. The structure of energy consumption in China is featured with the coal domination. Air pollution is becoming increasingly severe. As a result, we are confronted with the extremely arduous task to balance energy consumption and environmental protection. In order to coordinate the relationship between energy consumption and environmental protection in a strategic way, this paper analyzes comprehensively the instruments, effects and perspectives of energy-related environmental management. Meanwhile, this paper illustrates the barriers and challenges facing the energy and energy-related environmental management in China, and suggests a priority strategy of management instrument, mainly composed of energy-saving, optimization of energy structure, promulgation of environmental standards, advance in environmental technologies, internalization of environmental costs, establishment of a public benefit fund and adoption of a Renewable Portfolio System. 相似文献
102.
Poroussilicon(PS)wasfoundtoemitvisibleluminescenceatroomtemperaturebyCanhamin1990[1].Thisphenomenonimpliedapotentialapplicati... 相似文献
103.
A FISH technique for simultaneous detection of fluorescent R-band and in situ hybridization signals]
BACKGROUND: Because of serious adverse effects of centrally acting antitussive agents, is necessary to find new drugs with cough-suppressing activity. Medicinal herbs are a potential source of polysaccharides with high antitussive efficiency and on the other with minimal side effects. AIM: The study was to assess the antitussive action of mixture of a polysaccharides (RL) and polysaccharide-xylan (XY), both isolated from above-ground parts of Rudbeckie fulgida var. sullivantii. The observed activity was compared to those of narcotic and nonnarcotic antitussive substances used in clinical practice. METHODS: Cough was evoked by mechanical irritation of the airways in nonanaesthetized cats with chronic tracheal cannuly. The plant substances were administered perorally in the dose of 50 mg per kg body weight. RESULTS: Results indicate, that administration of RL induced a suppression of the followed cough parameters from both areas of airways (total fall in cough parameters by 46.6%). Administration of xylan induced the fall in the followed cough parameters with more significant influence on the laryngopharyngeal area of the airways (total fall in cough parameters 48.2%). CONCLUSION: Administration of RL and xylan did not achieve the effect of codeine, but had a more intensive antitussive effect than the peripherally acting droprozine and prenoxdiazine. (Fig. 3, Ref. 11.) 相似文献
104.
有机薄膜电致发光现象及其广阔的应用前景,激发了人们的研究兴趣。本文介绍了器件结构的研究现状。 相似文献
105.
介绍了高温超导红外探测器电极材料的选择和制备。选用先蒸、后蒸金,再合金化的电极工艺。芯片装配成器件后,器件性能稳定,膜层牢固,接触电阻小。 相似文献
106.
107.
主要介绍20.4K低温氦气经过加温后给液氧贮箱增压的试验技术。对试验设备、试验方法、试验过程及试验结果做了简要的介绍。 相似文献
108.
109.
Six compounds were isolated from the fruits of Luffa cylindrica. They were identified as lucyosides C, E, F, H, a mixture of alpha-spinasterol and stigmasta-7,22,25-trien-3 beta-OH and a mixture of alpha-spinasteryl glucoside and delta 7,22,25-stigmasteryl-beta-D-glucoside by means of chemical evidence and spectral analysis. 相似文献
110.
文章阐述了建设一支适合本企业IT运维的专业队伍,通过应用IT技术掌控运维队伍,使IT运维业务正常、有序、高效开展的思路,为生产管理服务,提供一个安全、可靠、高效、快捷的信息网络平台。 相似文献