全文获取类型
收费全文 | 294634篇 |
免费 | 26102篇 |
国内免费 | 13747篇 |
专业分类
电工技术 | 18242篇 |
技术理论 | 29篇 |
综合类 | 19741篇 |
化学工业 | 47786篇 |
金属工艺 | 17043篇 |
机械仪表 | 19236篇 |
建筑科学 | 23414篇 |
矿业工程 | 9920篇 |
能源动力 | 8399篇 |
轻工业 | 18460篇 |
水利工程 | 5340篇 |
石油天然气 | 19611篇 |
武器工业 | 2534篇 |
无线电 | 33653篇 |
一般工业技术 | 33595篇 |
冶金工业 | 15303篇 |
原子能技术 | 3201篇 |
自动化技术 | 38976篇 |
出版年
2024年 | 1404篇 |
2023年 | 4980篇 |
2022年 | 9105篇 |
2021年 | 12694篇 |
2020年 | 9780篇 |
2019年 | 7946篇 |
2018年 | 8957篇 |
2017年 | 10084篇 |
2016年 | 8946篇 |
2015年 | 12283篇 |
2014年 | 15550篇 |
2013年 | 18240篇 |
2012年 | 20130篇 |
2011年 | 21552篇 |
2010年 | 18944篇 |
2009年 | 17783篇 |
2008年 | 17175篇 |
2007年 | 16154篇 |
2006年 | 16003篇 |
2005年 | 13629篇 |
2004年 | 9170篇 |
2003年 | 7462篇 |
2002年 | 6591篇 |
2001年 | 5754篇 |
2000年 | 6163篇 |
1999年 | 7062篇 |
1998年 | 5815篇 |
1997年 | 4785篇 |
1996年 | 4482篇 |
1995年 | 3748篇 |
1994年 | 3003篇 |
1993年 | 2104篇 |
1992年 | 1630篇 |
1991年 | 1319篇 |
1990年 | 993篇 |
1989年 | 787篇 |
1988年 | 582篇 |
1987年 | 361篇 |
1986年 | 298篇 |
1985年 | 205篇 |
1984年 | 148篇 |
1983年 | 117篇 |
1982年 | 134篇 |
1981年 | 109篇 |
1980年 | 88篇 |
1979年 | 52篇 |
1978年 | 28篇 |
1977年 | 21篇 |
1976年 | 37篇 |
1959年 | 15篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
Thermoresponsive behavior and rheology of SiO2–hyaluronic acid/poly(N‐isopropylacrylamide) (NaHA/PNIPAm) core–shell structured microparticles 下载免费PDF全文
92.
93.
94.
95.
Dongdong Ji Zheng Liu Bailing Jiang Xiaofei Luo 《International Journal of Hydrogen Energy》2021,46(27):13960-13970
The evaluation of cell's weatherability is of practical interest. To further improve the soluble lead flow battery's weatherability, physiochemical properties of electrolytes containing fluoborate, perchlorate, methanesulfonate and trifluoromethanesulfonate are investigated from ?60 to 50 °C. Activities of CF3SO3H and HClO4 are poor in trifluoromethanesulfonate and perchlorate solutions due to common anion effect. The solubility of lead salt can be improved by increasing temperature, but worsened by increasing acid's content. With the temperature increasing, the conductivity is enhanced, and the viscosity is lowered for four solutions. The same results have been found by increasing acid's content except for CF3SO3H. The high energy efficiency can be achieved for cells over ?40–0 °C using fluoborate and perchlorate solutions, 73.2% at ?40 °C and 78.1% at ?30 °C respectively. Over the temperature range of 20–50 °C, the cells with methanesulfonate and trifluoromethanesulfonate solutions have good performance, 77.4% and 73.7% at 50 °C respectively. 相似文献
96.
97.
98.
99.
100.
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