全文获取类型
收费全文 | 576篇 |
免费 | 20篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 26篇 |
化学工业 | 125篇 |
金属工艺 | 21篇 |
机械仪表 | 16篇 |
建筑科学 | 15篇 |
能源动力 | 14篇 |
轻工业 | 51篇 |
水利工程 | 8篇 |
石油天然气 | 2篇 |
无线电 | 49篇 |
一般工业技术 | 107篇 |
冶金工业 | 105篇 |
原子能技术 | 12篇 |
自动化技术 | 46篇 |
出版年
2023年 | 4篇 |
2022年 | 14篇 |
2021年 | 16篇 |
2020年 | 6篇 |
2019年 | 8篇 |
2018年 | 12篇 |
2017年 | 18篇 |
2016年 | 15篇 |
2015年 | 10篇 |
2014年 | 21篇 |
2013年 | 28篇 |
2012年 | 23篇 |
2011年 | 38篇 |
2010年 | 25篇 |
2009年 | 17篇 |
2008年 | 20篇 |
2007年 | 15篇 |
2006年 | 14篇 |
2005年 | 16篇 |
2004年 | 14篇 |
2003年 | 14篇 |
2002年 | 18篇 |
2001年 | 10篇 |
2000年 | 9篇 |
1999年 | 12篇 |
1998年 | 51篇 |
1997年 | 25篇 |
1996年 | 22篇 |
1995年 | 6篇 |
1994年 | 9篇 |
1993年 | 10篇 |
1992年 | 3篇 |
1991年 | 5篇 |
1990年 | 4篇 |
1989年 | 5篇 |
1988年 | 5篇 |
1987年 | 3篇 |
1986年 | 3篇 |
1984年 | 6篇 |
1983年 | 6篇 |
1982年 | 7篇 |
1981年 | 6篇 |
1980年 | 2篇 |
1979年 | 5篇 |
1978年 | 4篇 |
1977年 | 5篇 |
1976年 | 2篇 |
1974年 | 2篇 |
1973年 | 2篇 |
1967年 | 1篇 |
排序方式: 共有597条查询结果,搜索用时 0 毫秒
71.
We describe two cases of acute embolic occlusion of the internal carotid artery and the middle cerebral artery in association with a patent accessory middle cerebral artery. Because of the presence of the accessory middle cerebral artery, the frontal lobe was salvaged to some extent, but it did not provide sufficient collateral blood supply to the middle cerebral artery territory to spare the rest of the frontal lobe, the temporal lobe, and the basal ganglia. 相似文献
72.
A method to treat lower limb ischemia associated with the insertion of an intraaortic balloon catheter is herein reported. A low dose of prostaglandin E1 was administered into the descending aorta continuously from the tip of the intraaortic balloon catheter. Immediately after the administration of prostaglandin E1 in patients whose lower limbs were ischemic due to obstruction with the catheter, the peripheral circulation of the ischemic limbs recovered with minimal changes in the systemic arterial blood pressure. This method is simple and noninvasive and was found to induce a satisfactory effect. 相似文献
73.
A new process configuration combining anaerobic digestion with ozonation, and operated at long SRT, was studied with the objective of on-site reduction in sludge quantity and improving biogas recovery. The process performance with respect to solid reduction efficiency and other important process parameters like accumulation of inorganic solids, changes in sludge viscosity and dewatering characteristics were evaluated from the data of long term pilot scale continuous experiments conducted using a mixture of primary and secondary municipal sewage sludge. Due to sludge ozonation and long SRT, high VSS degradation efficiency of approximately 80% was achieved at a reactor solid concentration of 6.5%. A high fraction of inorganic solid (>50%) consisting mainly of acid insoluble and iron compounds was found to accumulate in the reactor. The high inorganic content accumulated in the digested sludge did not, however, contribute to the observed increase in sludge viscosity at high solid concentration. The sludge viscosity was largely found to depend on the organic solid concentration rather than the total solid content. Moreover, higher inorganic content in the digested sludge resulted in better sludge dewaterability. For a quick assessment of the economic feasibility of the new process, an economic index based on the unit cost of digested sludge disposal to unit electric cost is proposed. 相似文献
74.
A bandwidth compression system for picture signals called the time-axis transform (TAT) system is introduced. It can be applied to various systems for transmission and recording of picture signals, such as the satellite broadcast system of high-definition television. The TAT compresses the bandwidth by reducing the number of transmitted pixels. The transmitted pixels consist of two kinds: basic pixels and additional pixels. The location of the former is fixed and that of the latter varies from picture to picture to minimize the interpolation error in the reconstructed picture. Thus, the TAT is a hybrid of fixed sampling and variable sampling systems. It compresses the bandwidth of the picture signal to one half or less, keeping high picture quality for both still and moving pictures. The feasibility of the TAT is demonstrated by an experimental system 相似文献
75.
76.
AH Sarker S Ikeda H Nakano H Terato H Ide K Imai K Akiyama K Tsutsui Z Bo K Kubo K Yamamoto A Yasui MC Yoshida S Seki 《Canadian Metallurgical Quarterly》1998,282(4):761-774
The association patterns between maternal anthropometric characteristics (stature, prepregnancy weight, prepregnancy body mass index, pregnancy weight gain) and newborn size (birth weight, length, head circumference) were tested with 10,240 single births taking place between 1985 and 1995 in Vienna, Austria, and 3,452 single births taking place between 1989 and 1995 in Westerstede-Ammerland (Friesland), northern Germany. Maternal size and newborn size differed highly significantly (p < 0.001) between the two genetically and socioeconomically different population groups. Furthermore, the incidence of macrosomia among newborns (birth weight greater than 4000 g) was extraordinarily high (17.9%) in the Frisian group from northern Germany. In both populations taller and heavier women with a higher weight gain during pregnancy gave birth to heavier offspring. Nevertheless, the pregnancy weight gain, which indicates environmental conditions of the mother, had only a minor impact on newborn size compared with stature and prepregnancy weight, which reflect the maternal genetic potential to a higher degree. 相似文献
77.
78.
A small 20 × 20 dot matrix array of a FET has been fabricated on a glass substrate using a-Si films as the semiconductor and silicon nitride deposited from a N2-SiH4 mixture as the gate insulator. Good operation is obtained for both TN-mode and GH-mode in transparent-type LCDs. The improved fabrication process and structure are reported. 相似文献
79.
80.
A novel anaerobic digestion process combined with partial ozonation on digested sludge was demonstrated for improving sludge digestion and biogas recovery by full-scale testing for 2 years and its performance was compared with a simultaneously operated conventional anaerobic digestion process. The novel process requires two essential modifications, which are ozonation for enhancing the biological degradability of sludge organics and concentrating of solids in the digester through a solid/liquid separation for extension of SRT. These modifications resulted in high VSS degradation efficiency of ca. 88%, as much as 1.3 times of methane production and more than 70% reduction in dewatered sludge cake production. Based on the performance, its energy demands and contribution for minimisation of greenhouse gas emission was evaluated throughout an entire study of sludge treatment and disposal schemes in a municipality for 130,000 p.e. The analysis indicated that the novel process with power generation from biogas would lead to minimal greenhouse gas emission because the extra energy production from the scheme was expected to cover all of the energy demand for the plant operation, and the remarkable reduction in dewatered sludge cake volumes makes it possible to reduce N2O discharge and consumption of fossil fuel in the subsequent sludge incineration processes. 相似文献