全文获取类型
收费全文 | 29342篇 |
免费 | 2188篇 |
国内免费 | 1231篇 |
专业分类
电工技术 | 1361篇 |
技术理论 | 6篇 |
综合类 | 1951篇 |
化学工业 | 5150篇 |
金属工艺 | 1831篇 |
机械仪表 | 1812篇 |
建筑科学 | 2262篇 |
矿业工程 | 797篇 |
能源动力 | 797篇 |
轻工业 | 1681篇 |
水利工程 | 497篇 |
石油天然气 | 1958篇 |
武器工业 | 159篇 |
无线电 | 3191篇 |
一般工业技术 | 3719篇 |
冶金工业 | 1576篇 |
原子能技术 | 391篇 |
自动化技术 | 3622篇 |
出版年
2024年 | 109篇 |
2023年 | 471篇 |
2022年 | 745篇 |
2021年 | 1064篇 |
2020年 | 806篇 |
2019年 | 683篇 |
2018年 | 775篇 |
2017年 | 842篇 |
2016年 | 845篇 |
2015年 | 1001篇 |
2014年 | 1344篇 |
2013年 | 1655篇 |
2012年 | 1685篇 |
2011年 | 1940篇 |
2010年 | 1743篇 |
2009年 | 1686篇 |
2008年 | 1603篇 |
2007年 | 1437篇 |
2006年 | 1432篇 |
2005年 | 1294篇 |
2004年 | 978篇 |
2003年 | 997篇 |
2002年 | 1060篇 |
2001年 | 1027篇 |
2000年 | 794篇 |
1999年 | 871篇 |
1998年 | 728篇 |
1997年 | 580篇 |
1996年 | 524篇 |
1995年 | 430篇 |
1994年 | 375篇 |
1993年 | 267篇 |
1992年 | 209篇 |
1991年 | 153篇 |
1990年 | 120篇 |
1989年 | 105篇 |
1988年 | 76篇 |
1987年 | 52篇 |
1986年 | 55篇 |
1985年 | 24篇 |
1984年 | 29篇 |
1983年 | 27篇 |
1982年 | 20篇 |
1981年 | 19篇 |
1980年 | 9篇 |
1979年 | 12篇 |
1978年 | 5篇 |
1976年 | 13篇 |
1970年 | 6篇 |
1966年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 9 毫秒
1.
This study was undertaken to develop a modified atmosphere package to control microbial growth in ready‐to‐eat (RTE) products stored at ambient temperature. Ethanol and/or limonene associated with modified atmosphere (CO2 : O2 : N2 = 30% : 5% : 65%) was used to inhibit the growth of total air‐borne microorganisms and Escherichia coli in RTE products stored at 25°C. The results indicated that 0.05% ethanol vapour in the headspace was effective to inhibit the growth of air‐borne microorganisms and E. coli at 25°C for 72 h in a model study, and the effectiveness was related to ethanol content. Both 73 ppm limonene and 0.05% ethanol vapour enhanced the bacteriostatic effect of modified atmosphere in RTE sushi roll products, and no off‐flavour was detected using this formulated gas; however, no significant inhibitory effect was observed for RTE cold noodle products. This study concludes that combinations of carbon dioxide, ethanol or limonene vapours are effective to inhibit microbial growth in RTE food at ambient temperature, and the outcome may be due to the hurdle effect. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
2.
3.
中国古典园林三维造型研究 总被引:1,自引:0,他引:1
论述了采用层次结构化及参数化三维造型方法,建立一个以造型函数库为核心,从而构造各类、各级园林景观构件表面模型的方法和过程。对于某些非建筑类的园林配景构件,采用了Fractal方法进行造型。 相似文献
4.
Junwei Fu Zhengbiao Zhang Zhenping Cheng Jian Zhu Wei Zhang Xiulin Zhu 《Polymer Bulletin》2008,61(3):287-297
A novel reversible addition-fragmentation chain transfer (RAFT) reagent bearing triphenylamine (TPA)
group, 4-diphenylamino-dithiobenzoic acid benzyl ester (DDABE), was designed and synthesized. It was used
in the RAFT polymerizations of styrene (St) and methyl acrylate (MA) to prepare end-functionalized polymers.
The results of the polymerization showed that the RAFT polymerizations could be well controlled using DDABE
as the RAFT agent. Number-average molecular weight (Mn,GPC) increased linearly
with monomer conversion, and molecular weight distributions were relatively narrow (PDI<
1.50). The results of chain-extension reaction, 1H NMR spectra and UV/Vis
spectra confirmed that most of the polymers chains were end-capped by the functional triphenylamine
(TPA) groups. The effect of feed molar ratios of St/DDABE/AIBN on polymerization was investigated. 相似文献
5.
Yi‐Hung Chen Ching‐Yuan Chang Wei‐Ling Su Chun‐Yu Chiu Yue‐Hwa Yu Pen‐Chi Chiang Chiung‐Fen Chang Je‐Lueng Shie Chyow‐San Chiou Sally IM Chiang 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2005,80(1):68-75
This study investigates the ozonation of CI Reactive Black 5 (RB5) by using the rotating packed bed (RPB) and completely stirred tank reactor (CSTR) as ozone contactors. The RPB, which provides high gravitational force by adjusting the rotational speed, was employed as a novel ozone contactor. The same ozone dosage was separately introduced into either the RPB or the CSTR for the investigation, while the experimental solution was continuously circulated within the apparatus consisting of the RPB and CSTR. The decolorization and mineralization efficiencies of RB5 in the course of ozonation are compared for these two methods. Moreover, the dissolved and off‐gas ozone concentrations were simultaneously monitored for the further analysis. As a result, the ozone mass transfer rate per unit volume of the RPB was significantly higher because of its higher mass transfer coefficient and gas–liquid concentration driving force. Furthermore, ozonation kinetics was found to be independent of the gravitational magnitude of an ozone gas–liquid contactor. Therefore, the results suggest employing RPBs as ozone‐contacting devices with the advantage of volume reduction. The experimental results, which can be used for further modeling of the ozonation process in the RPB, also show the requirement of correct design for the RPB. Consequently, the present study is useful for the understanding of practical application of RPBs. Copyright © 2004 Society of Chemical Industry 相似文献
6.
哈尔滨炼油厂MTBE装置试生产 总被引:4,自引:0,他引:4
介绍了哈尔滨炼油厂MTBE装置的工艺路线、新技术的应用及特点;催化剂的装填及应用情况;总结了生产过程中遇到的一系列问题及解决办法;探索了平稳生产的新徐径,以保证装置安全、平稳、长周期运行;同时对反应器操作温度、催化蒸馏塔操作压力、原料中醇烯比等因素对异丁烯转化率及MTBE产品的影响做了简单的总结。 相似文献
7.
8.
本文针对天然气井提高钻井速度问题,总结分析了盆地中部井身结构,水力、机械参数,聚合物钻井液,正注反挤固井等工艺技术对该地区钻速的影响。指出提高天然气井钻井速度,必须搞好系统工程,形成配套技术。 相似文献
9.
应用不同剂量的~(60)Coγ射线照射含NT株弓形虫包囊的鼠脑匀浆后,以0.4%胰蛋白酶液消化,使弓形虫缓殖子从包囊中释放出来,并用生理盐水作连续10倍稀释,使成为含不同数量缓殖子的悬液,将此悬液接种小鼠,用生物检测方法确定其感染性。另设未经照射处理的缓殖子悬液感染小鼠的对照组。结果表明,γ射线0.55kGy剂量为控制鼠脑中NT株弓形虫感染性的最小有效剂量。γ射线0.1kGy剂量对弓形虫缓殖子感染性无明显影响,而0.45kGy照射后,其感染性较前者下降了10~4倍。 相似文献
10.