全文获取类型
收费全文 | 241614篇 |
免费 | 2979篇 |
国内免费 | 426篇 |
专业分类
电工技术 | 4297篇 |
综合类 | 258篇 |
化学工业 | 39540篇 |
金属工艺 | 9388篇 |
机械仪表 | 7402篇 |
建筑科学 | 5480篇 |
矿业工程 | 1392篇 |
能源动力 | 5200篇 |
轻工业 | 24851篇 |
水利工程 | 2484篇 |
石油天然气 | 5094篇 |
武器工业 | 32篇 |
无线电 | 25133篇 |
一般工业技术 | 44841篇 |
冶金工业 | 45355篇 |
原子能技术 | 5950篇 |
自动化技术 | 18322篇 |
出版年
2021年 | 2144篇 |
2019年 | 2038篇 |
2018年 | 3521篇 |
2017年 | 3461篇 |
2016年 | 3730篇 |
2015年 | 2260篇 |
2014年 | 3939篇 |
2013年 | 10226篇 |
2012年 | 6181篇 |
2011年 | 8356篇 |
2010年 | 6591篇 |
2009年 | 7275篇 |
2008年 | 7611篇 |
2007年 | 7753篇 |
2006年 | 6907篇 |
2005年 | 6061篇 |
2004年 | 5827篇 |
2003年 | 5604篇 |
2002年 | 5681篇 |
2001年 | 5564篇 |
2000年 | 5386篇 |
1999年 | 5310篇 |
1998年 | 12575篇 |
1997年 | 8899篇 |
1996年 | 6858篇 |
1995年 | 5332篇 |
1994年 | 4739篇 |
1993年 | 4630篇 |
1992年 | 3668篇 |
1991年 | 3389篇 |
1990年 | 3595篇 |
1989年 | 3474篇 |
1988年 | 3304篇 |
1987年 | 2895篇 |
1986年 | 2932篇 |
1985年 | 3376篇 |
1984年 | 3221篇 |
1983年 | 2892篇 |
1982年 | 2738篇 |
1981年 | 2821篇 |
1980年 | 2720篇 |
1979年 | 2624篇 |
1978年 | 2685篇 |
1977年 | 2948篇 |
1976年 | 3805篇 |
1975年 | 2368篇 |
1974年 | 2242篇 |
1973年 | 2376篇 |
1972年 | 1970篇 |
1971年 | 1858篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
Lissy Z. F. Gross Mariana Sacerdoti Prof. Albrecht Piiper Prof. Stefan Zeuzem Dr. Alejandro E. Leroux Dr. Ricardo M. Biondi 《ChemMedChem》2020,15(18):1682-1690
Angiotensin converting enzyme 2 (ACE2) is the human receptor that interacts with the spike protein of coronaviruses, including the one that produced the 2020 coronavirus pandemic (COVID-19). Thus, ACE2 is a potential target for drugs that disrupt the interaction of human cells with SARS-CoV-2 to abolish infection. There is also interest in drugs that inhibit or activate ACE2, that is, for cardiovascular disorders or colitis. Compounds binding at alternative sites could allosterically affect the interaction with the spike protein. Herein, we review biochemical, chemical biology, and structural information on ACE2, including the recent cryoEM structures of full-length ACE2. We conclude that ACE2 is very dynamic and that allosteric drugs could be developed to target ACE2. At the time of the 2020 pandemic, we suggest that available ACE2 inhibitors or activators in advanced development should be tested for their ability to allosterically displace the interaction between ACE2 and the spike protein. 相似文献
42.
43.
44.
45.
46.
47.
48.
49.
Georgios Tsaparlis 《Israel journal of chemistry》2019,59(6-7):478-492
Numerous conceptual difficulties and misconceptions have been reported in the science and chemistry education literature about electrochemistry concepts such as electrolytes, redox equations, and about electrochemical (galvanic and electrolytic) cells. Other studies have considered teaching approaches aimed at improving learning and at overcoming misconceptions. This paper reviews these studies and considers strategies and approaches for the effective teaching of electrochemistry. Then, the review focuses on problem solving in equilibrium electrochemistry, especially problems involving the Nernst equation. The main findings of four studies with Greek university chemistry students, dealing with: (i) algorithmic problem‐solving ability; (ii) practice on problem solving; (iii) the effect of the format of a problem; and (iv) the construction and evaluation of a website devoted to electrochemistry problem solving, are reported. 相似文献
50.
ARIMA is seldom used in supply chains in practice. There are several reasons, not the least of which is the small sample size of available data, which restricts the usage of the model. Keeping in mind this restriction, we discuss in this paper a state-space ARIMA model with a single source of error and show how it can be efficiently used in the supply-chain context, especially in cases when only two seasonal cycles of data are available. We propose a new order selection algorithm for the model and compare its performance with the conventional ARIMA on real data. We show that the proposed model performs well in terms of both accuracy and computational time in comparison with other ARIMA implementations, which makes it efficient in the supply-chain context. 相似文献