全文获取类型
收费全文 | 2648篇 |
免费 | 35篇 |
专业分类
电工技术 | 35篇 |
综合类 | 21篇 |
化学工业 | 565篇 |
金属工艺 | 54篇 |
机械仪表 | 65篇 |
建筑科学 | 87篇 |
矿业工程 | 1篇 |
能源动力 | 35篇 |
轻工业 | 519篇 |
水利工程 | 7篇 |
石油天然气 | 1篇 |
无线电 | 158篇 |
一般工业技术 | 427篇 |
冶金工业 | 386篇 |
原子能技术 | 23篇 |
自动化技术 | 299篇 |
出版年
2022年 | 26篇 |
2021年 | 35篇 |
2020年 | 32篇 |
2019年 | 25篇 |
2018年 | 23篇 |
2016年 | 43篇 |
2015年 | 27篇 |
2014年 | 47篇 |
2013年 | 63篇 |
2012年 | 66篇 |
2011年 | 103篇 |
2010年 | 78篇 |
2009年 | 76篇 |
2008年 | 87篇 |
2007年 | 83篇 |
2006年 | 74篇 |
2005年 | 88篇 |
2004年 | 69篇 |
2003年 | 55篇 |
2002年 | 56篇 |
2001年 | 52篇 |
2000年 | 52篇 |
1999年 | 54篇 |
1998年 | 131篇 |
1997年 | 88篇 |
1996年 | 59篇 |
1995年 | 60篇 |
1994年 | 50篇 |
1993年 | 49篇 |
1992年 | 45篇 |
1991年 | 23篇 |
1990年 | 29篇 |
1989年 | 24篇 |
1988年 | 29篇 |
1987年 | 35篇 |
1986年 | 36篇 |
1985年 | 43篇 |
1984年 | 39篇 |
1981年 | 27篇 |
1980年 | 28篇 |
1979年 | 24篇 |
1978年 | 29篇 |
1977年 | 38篇 |
1976年 | 39篇 |
1974年 | 36篇 |
1973年 | 24篇 |
1972年 | 19篇 |
1971年 | 21篇 |
1970年 | 22篇 |
1967年 | 27篇 |
排序方式: 共有2683条查询结果,搜索用时 0 毫秒
1.
Bernette Maria Oosterlaken Heiner Friedrich Gijsbertus de With 《Microscopy research and technique》2022,85(1):412-417
Transmission electron microscopy (TEM) is an important analysis technique to visualize (bio)macromolecules and their assemblies, including collagen fibers. Many protocols for TEM sample preparation of collagen involve one or more washing steps to remove excess salts from the dispersion that could hamper analysis when dried on a TEM grid. Such protocols are not standardized and washing times as well as washing solvents vary from procedure to procedure, with each research group typically having their own protocol. Here, we investigate the influence of washing with water, ethanol, but also methanol and 2-propanol, for both mineralized and unmineralized collagen samples via a protocol based on centrifugation. Washing with water maintains the hydrated collagen structure and the characteristic banding pattern can be clearly observed. Conversely, washing with ethanol results in dehydration of the fibrils, often leading to aggregation of the fibers and a less obvious banding pattern, already within 1 min of ethanol exposure. As we show, this process is fully reversible. Similar observations were made for methanol and propanol. Based on these results, a standardized washing protocol for collagenous samples is proposed. 相似文献
2.
Gökelma Mertol Einarsrud Kristian Etienne Tranell Gabriella Friedrich Bernd 《Metallurgical and Materials Transactions B》2020,51(2):850-860
Metallurgical and Materials Transactions B - The quality requirements of aluminum products are steadily increasing, and the presence of non-metallic inclusions have a large impact on the quality of... 相似文献
3.
Kazuo Tsubota Stephen C. Pflugfelder Zuguo Liu Christophe Baudouin Hyo Myung Kim Elisabeth M. Messmer Friedrich Kruse Lingyi Liang Jimena Tatiana Carreno-Galeano Maurizio Rolando Norihiko Yokoi Shigeru Kinoshita Reza Dana 《International journal of molecular sciences》2020,21(23)
Over the past decades, the number of patients with dry eye disease (DED) has increased dramatically. The incidence of DED is higher in Asia than in Europe and North America, suggesting the involvement of cultural or racial factors in DED etiology. Although many definitions of DED have been used, discrepancies exist between the various definitions of dry eye disease (DED) used across the globe. This article presents a clinical consensus on the definition of DED, as formulated in four meetings with global DED experts. The proposed new definition is as follows: “Dry eye is a multifactorial disease characterized by a persistently unstable and/or deficient tear film (TF) causing discomfort and/or visual impairment, accompanied by variable degrees of ocular surface epitheliopathy, inflammation and neurosensory abnormalities.” The key criteria for the diagnosis of DED are unstable TF, inflammation, ocular discomfort and visual impairment. This definition also recommends the assessment of ocular surface epitheliopathy and neurosensory abnormalities in each patient with suspected DED. It is easily applicable in clinical practice and should help practitioners diagnose DED consistently. This consensus definition of DED should also help to guide research and clinical trials that, to date, have been hampered by the lack of an established surrogate endpoint. 相似文献
4.
Letters to the editor 总被引:6,自引:0,他引:6
5.
Third generation mobile radio systems are currently being deployed in different regions of the world. Future systems beyond the third generation are already under discussion in international bodies and forums such as ITU, WWRF and R&D programmes of the European Union and in other regions. These systems will determine the research and standardisation activities in mobile and wireless communication in the next years. Based on experience of the third generation, future systems will be developed mainly from the user perspective with respect to potential services and applications including traffic demands. Therefore, the Wireless World Research Forum was launched in 2001 as a global and open initiative of manufacturers, network operators, SMEs, R&D centres and the academic domain. WWRF is focused on the vision of such systems - the Wireless World-and potential key technologies. This paper describes the international context of activities on systems beyond third generation, the goals, objectives and structure of WWRF, the user perspective as the starting point for a future system design and the key enabling technologies for the Wireless World. 相似文献
6.
7.
In the power industry, current has to be measured for metering and protection purposes. Conventional sensor setups need two transformers to realize the high dynamic range. By the described mixed analog/digital signal processing algorithm, the inherent low photonic noise of the input signals was maintained up to the full sensor output. The system design is based on a rigorous investigation and optimization of the error sources in the signal processing chain. The results are proved by a demonstrator, achieving a dynamic range from 0.05 to 100 times the rated current and a ratio root mean square error of less than 0.5%. 相似文献
8.
9.
T Tillmann K Kamino C Dasenbrock H Ernst M Kohler G Morawietz E Campo A Cardesa L Tomatis U Mohr 《Canadian Metallurgical Quarterly》1997,49(3-4):197-200
An experiment using 4279 CBA/J mice of two generations was carried out to investigate the influence of parental preconceptual exposure to X-ray radiation or to chemical carcinogens. Microchips were implanted subcutaneously in the dorsolateral back for unique identification of each animal. The animals were kept for lifespan under standard laboratory conditions. In 36 mice a circumscribed neoplasm occurred in the area of the implanted microchip. Females were significantly more frequently affected than male mice. An influence of age or different treatment on the s.c. tumour incidence in two mice generations could not be observed. Macroscopically, firm, pale white nodules up to 25 mm in diameter with the microchip in its center were found. Microscopically, soft tissue tumours such as fibrosarcoma and malignant fibrous histiocytoma were detected. 相似文献
10.