全文获取类型
收费全文 | 4423篇 |
免费 | 219篇 |
国内免费 | 16篇 |
专业分类
电工技术 | 62篇 |
综合类 | 22篇 |
化学工业 | 872篇 |
金属工艺 | 106篇 |
机械仪表 | 85篇 |
建筑科学 | 150篇 |
矿业工程 | 8篇 |
能源动力 | 154篇 |
轻工业 | 530篇 |
水利工程 | 15篇 |
石油天然气 | 8篇 |
无线电 | 400篇 |
一般工业技术 | 808篇 |
冶金工业 | 648篇 |
原子能技术 | 38篇 |
自动化技术 | 752篇 |
出版年
2023年 | 66篇 |
2022年 | 136篇 |
2021年 | 182篇 |
2020年 | 119篇 |
2019年 | 116篇 |
2018年 | 127篇 |
2017年 | 134篇 |
2016年 | 157篇 |
2015年 | 114篇 |
2014年 | 181篇 |
2013年 | 225篇 |
2012年 | 247篇 |
2011年 | 263篇 |
2010年 | 168篇 |
2009年 | 175篇 |
2008年 | 171篇 |
2007年 | 147篇 |
2006年 | 120篇 |
2005年 | 81篇 |
2004年 | 92篇 |
2003年 | 66篇 |
2002年 | 72篇 |
2001年 | 71篇 |
2000年 | 51篇 |
1999年 | 52篇 |
1998年 | 203篇 |
1997年 | 115篇 |
1996年 | 73篇 |
1995年 | 51篇 |
1994年 | 43篇 |
1993年 | 49篇 |
1992年 | 27篇 |
1991年 | 30篇 |
1990年 | 32篇 |
1989年 | 35篇 |
1988年 | 28篇 |
1987年 | 20篇 |
1985年 | 21篇 |
1984年 | 20篇 |
1983年 | 21篇 |
1980年 | 21篇 |
1977年 | 27篇 |
1976年 | 44篇 |
1910年 | 26篇 |
1909年 | 36篇 |
1908年 | 26篇 |
1907年 | 50篇 |
1906年 | 33篇 |
1905年 | 44篇 |
1904年 | 49篇 |
排序方式: 共有4658条查询结果,搜索用时 15 毫秒
1.
2.
3.
Using an integrated process of data and modeling in HRA 总被引:1,自引:0,他引:1
John Wreathall Dennis Bley Emilie Roth Jordan Multer Thomas Raslear 《Reliability Engineering & System Safety》2004,83(2):221
The paper describes an approach taken to estimate the probabilities of failure associated with various railroad tasks to prevent accidents (principally collisions and derailments). These probabilities were estimated using an expert elicitation process that used partially relevant data available from a variety of databases and that were filtered and scaled to make them more directly relevant to the analyses being performed. Extensive qualitative studies were performed prior to the elicitation process to identify relevant contexts under which the tasks can be performed. 相似文献
4.
5.
J.M. Roth T.G. Ulmer N.W. Spellmeyer S. Constantine M.E. Grein 《Photonics Technology Letters, IEEE》2004,16(9):2009-2011
We demonstrate a novel 40-GHz mode-locked fiber laser that utilizes a single active device to provide both gain and mode-locking. The laser produces pulses as short as 2.2 ps, is tunable over a 27-nm band centered at 1553 nm, and exhibits long-term stability without cavity-length feedback control. The pulse train at 1556 nm was used in a 40-Gb/s transmission experiment over 45 km with a low 0.4-dB power penalty. 相似文献
6.
S Schumacher H Volkmer F Buck A Otto A Tarnók S Roth FG Rathjen 《Canadian Metallurgical Quarterly》1997,136(4):895-906
Chicken acidic leucine-rich EGF-like domain containing brain protein (CALEB) was identified by combining binding assays with immunological screens in the chicken nervous system as a novel member of the EGF family of differentiation factors. cDNA cloning indicates that CALEB is a multidomain protein that consists of an NH2-terminal glycosylation region, a leucine-proline-rich segment, an acidic box, a single EGF-like domain, a transmembrane, and a short cytoplasmic stretch. In the developing nervous system, CALEB is associated with glial and neuronal surfaces. CALEB is composed of a 140/130-kD doublet, an 80-kD band, and a chondroitinsulfate-containing 200-kD component. The latter two components are expressed in the embryonic nervous system and are downregulated in the adult nervous system. CALEB binds to the extracellular matrix glycoproteins tenascin-C and -R. In vitro antibody perturbation experiments reveal a participation of CALEB in neurite formation in a permissive environment. 相似文献
7.
Orthopedists being more engaged in surgery are often asked about problems concerning exercise science. This article will summarize the existing basic knowledge, very close to practice, and put down the leading steps of how to build up a (therapeutical) training programme. A lab block is recommended acting on a preventive as well as on a sportive medical base. 相似文献
8.
Converting cysteine 543 to tyrosine in the influenza virus hemagglutinin (HA) introduces both a basolateral sorting signal and an internalization signal into the HA cytoplasmic domain. Another HA mutant, HA+8, contains eight additional amino acids at the end of the cytoplasmic domain that include a powerful internalization signal. HA+8 was also sorted efficiently to the basolateral surface of Madin-Darby canine kidney cells. The simplest explanation for the observation that multiple sorting phenotypes depend upon the same small amino acid sequence is that certain tyrosine-based internalization signals might also function as basolateral sorting signals. To test this hypothesis, second-site mutations were introduced into HA C543Y or HA+8 to determine if the internalization and basolateral sorting functions can be separated. For HA C543Y, the same sequence positions were important for both basolateral sorting and internalization, but the two functions responded differently to individual amino acid replacements, indicating that they were distinct. For HA+8, the basolateral sorting signal required the same tyrosine as the internalization signal, but did not share any other characteristics. Thus, even when basolateral sorting signals that depend on tyrosine overlap or are co-linear with internalizations signals, the two sorting processes are sensitive to different characteristics of the sequence. 相似文献
9.
10.