全文获取类型
收费全文 | 2814篇 |
免费 | 26篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 19篇 |
化学工业 | 204篇 |
金属工艺 | 71篇 |
机械仪表 | 19篇 |
建筑科学 | 61篇 |
能源动力 | 44篇 |
轻工业 | 126篇 |
水利工程 | 4篇 |
石油天然气 | 6篇 |
无线电 | 148篇 |
一般工业技术 | 229篇 |
冶金工业 | 1744篇 |
原子能技术 | 5篇 |
自动化技术 | 161篇 |
出版年
2023年 | 5篇 |
2022年 | 9篇 |
2021年 | 18篇 |
2020年 | 11篇 |
2019年 | 11篇 |
2018年 | 15篇 |
2017年 | 22篇 |
2016年 | 20篇 |
2015年 | 32篇 |
2014年 | 30篇 |
2013年 | 55篇 |
2012年 | 42篇 |
2011年 | 66篇 |
2010年 | 52篇 |
2009年 | 52篇 |
2008年 | 55篇 |
2007年 | 59篇 |
2006年 | 40篇 |
2005年 | 47篇 |
2004年 | 45篇 |
2003年 | 44篇 |
2002年 | 43篇 |
2001年 | 30篇 |
2000年 | 27篇 |
1999年 | 100篇 |
1998年 | 540篇 |
1997年 | 303篇 |
1996年 | 234篇 |
1995年 | 126篇 |
1994年 | 139篇 |
1993年 | 107篇 |
1992年 | 23篇 |
1991年 | 28篇 |
1990年 | 42篇 |
1989年 | 39篇 |
1988年 | 28篇 |
1987年 | 22篇 |
1986年 | 24篇 |
1985年 | 23篇 |
1984年 | 10篇 |
1983年 | 4篇 |
1982年 | 10篇 |
1981年 | 16篇 |
1980年 | 19篇 |
1979年 | 7篇 |
1978年 | 8篇 |
1977年 | 41篇 |
1976年 | 92篇 |
1975年 | 7篇 |
1973年 | 5篇 |
排序方式: 共有2841条查询结果,搜索用时 31 毫秒
1.
Nicolas Larché Benoit Emo Audrey Allion Elisabeth Johansson Dominique Thierry 《工业材料与腐蚀》2021,72(8):1338-1349
With lower alloying cost and higher mechanical properties, lean duplex stainless steels can be an alternative to the more commonly used austenitic stainless steels. However, these alloys are still not the preferred choice, probably due to a lack of field experience. A study was thus initiated in view of defining the limits of use of selected (lean) duplexes for urban wastewater treatment units. The present paper shows the localized corrosion performance of selected lean duplexes in chloride contaminated solutions. The results are compared with austenitic S30403 and S31603 and with the more standard duplexes S82441 and S32205. The effect of welding was also investigated. Exposures in field municipal wastewater plants were conducted for 1 year in low and high chloride content units. The results show that lean duplexes S32101 and S32202 can be used as alternatives to S30403 and S31603 in low chloride electrolytes. At 500 ppm of chloride content, duplex stainless steel S32304 showed better corrosion resistance than S30403 and S31603. For higher chloride contents (1000 ppm and above) the standard duplexes S82441 and S32205 shall be preferred. 相似文献
2.
3.
SG Bryant 《Canadian Metallurgical Quarterly》1996,53(19):2339-40, 2343
4.
SG Rijpkema RG Herbes N Verbeek-De Kruif JF Schellekens 《Canadian Metallurgical Quarterly》1996,117(3):563-566
Epiglottic disruption is an uncommon injury usually associated with significant supraglottic trauma. This injury may be overlooked because of the difficulty in examining the larynx or other associated severe injuries. We present two cases of clinically unsuspected epiglottic disruption that were first seen on MR images of the neck. 相似文献
5.
SA Khotimchenko VM Kodentsova IA Alekseeva SG Vlaskina OA Vrzhesinskaia AA Sokol''nikov LA Kharitonchik IP Aleshko-Ozhevskií LV Sheviakova 《Canadian Metallurgical Quarterly》1997,43(3):158-164
Gamma delta T-Cells represent a minor subpopulation of T-lymphocytes in man and their role in normal and diseased human skin is unknown. This article is a comprehensive review of T-lymphocytes bearing the gamma delta T-cell receptor in normal and pathological human skin. Firstly, we have documented the occurrence of gamma delta T-cells in normal skin and in a range of reactive and malignant skin conditions. We have then discussed the experimental findings regarding the repertoire used by gamma delta T-cells in normal human skin and in cutaneous disorders with an increased percentage of gamma delta T-cells. 相似文献
6.
射频电路设计人员常用的一条经验法则是:有源器件的fT至少应为工作频率的十倍时,现代无线设备中的射频电路才会具有良好的性能. 相似文献
7.
8.
Agglomeration and networks in spatial economies 总被引:1,自引:0,他引:1
We consider the parallel developments in the economics of agglomeration and the economics of networks. We explore the complementarities between the productivity benefits of agglomeration and those of network linkages, arguing that networks of actors dispersed over space may substitute for agglomerations of actors at a single point.JEL Classification:
D20, L14, R30 相似文献
9.
Henrik Pettersson Tadeusz Gruszecki Lars-Henrik Johansson Per Johander 《Solar Energy Materials & Solar Cells》2003,77(4):6595
A manufacturing technique for monolithic dye-sensitised solar cells is presented. Encapsulated modules designed for indoor low-power applications have been prepared using industrial methods and equipment. Under certain conditions (light intensity <5000 lx, temperature between –10°C and 50°C, and relative humidity of appr. 50%), the modules have performed well and shown excellent long-term stability. Moreover, modules withstand illumination in combination with storage at 100% relative humidity. However, a certain degradation of the module performance takes place at illuminations exceeding 5000 lx and temperatures exceeding 50°C. 相似文献
10.
Human immunodeficiency virus (HIV) infection of the thymus could have profound effects on development of the immune response, particularly in children. We and others have established that in addition to infecting and depleting CD4-bearing thymocytes, functional HIV proviruses are found in thymocytes lacking surface CD4 expression. Using in vitro thymocyte cultures, we show that neither HIV-mediated down regulation of CD4 nor CD4-independent infection contributes to the localization of HIV in cells lacking the primary virus receptor. Rather, infection of a CD4-positive precursor cell (CD4 positive/CD8 positive) with subsequent differentiation into a mature CD4-negative phenotype results in productively infected CD4-negative cells. This novel mechanism may contribute to pathogenesis by distributing viral sequences into functional subsets of T cells typically refractory to HIV infection and could account for the presence of viral DNA in CD8-positive lymphocytes recently observed in patients. 相似文献