全文获取类型
收费全文 | 919篇 |
免费 | 19篇 |
国内免费 | 29篇 |
专业分类
电工技术 | 7篇 |
综合类 | 34篇 |
化学工业 | 93篇 |
金属工艺 | 52篇 |
机械仪表 | 219篇 |
建筑科学 | 18篇 |
矿业工程 | 5篇 |
能源动力 | 23篇 |
轻工业 | 55篇 |
水利工程 | 6篇 |
石油天然气 | 107篇 |
武器工业 | 1篇 |
无线电 | 97篇 |
一般工业技术 | 74篇 |
冶金工业 | 26篇 |
原子能技术 | 12篇 |
自动化技术 | 138篇 |
出版年
2023年 | 10篇 |
2022年 | 3篇 |
2021年 | 16篇 |
2020年 | 13篇 |
2019年 | 3篇 |
2018年 | 11篇 |
2017年 | 21篇 |
2016年 | 19篇 |
2015年 | 23篇 |
2014年 | 34篇 |
2013年 | 39篇 |
2012年 | 37篇 |
2011年 | 58篇 |
2010年 | 35篇 |
2009年 | 37篇 |
2008年 | 48篇 |
2007年 | 53篇 |
2006年 | 48篇 |
2005年 | 36篇 |
2004年 | 46篇 |
2003年 | 32篇 |
2002年 | 47篇 |
2001年 | 33篇 |
2000年 | 39篇 |
1999年 | 39篇 |
1998年 | 29篇 |
1997年 | 32篇 |
1996年 | 21篇 |
1995年 | 27篇 |
1994年 | 16篇 |
1993年 | 16篇 |
1992年 | 11篇 |
1991年 | 6篇 |
1990年 | 6篇 |
1989年 | 3篇 |
1988年 | 5篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1977年 | 1篇 |
1975年 | 1篇 |
1973年 | 1篇 |
1956年 | 2篇 |
排序方式: 共有967条查询结果,搜索用时 15 毫秒
51.
在分析中原油田开发中调剖措施的必要性及石灰泥、废纸浆,锯木灰等工业“三废”现状后,利用室内试验前后岩心渗透率,铸体图象,压汞毛管压力曲线,扫描电镜孔隙变化等分析结果,研究了石灰泥等工业“三废”在中原油田调剖的可行性。通过133井次的现场试验结果表明,石灰泥 业“三废”适用于中原油田水井调剖,结合目前注水冲刷地层孔隙结构变化的特点,还提出了配套改进办法和扩大应用规模的建议。 相似文献
52.
本文利用变分技术将Ti:NbO_3条带波导的波导模场分布分解成为两个相关的一维问题.对模参数和传播常数提供一种新的迭代近似方法.本方法收敛速度非常快,它对具有矩形横截面的光波导和扩散条带波导都适用。 相似文献
53.
As part of an overall investigation of flash-smelting processes, numerical computations were performed for the turbulent recirculating flow field of a gas jet in a confined cylindrical system. The two-equation (k - e) model was used to describe turbulence. The two-dimensional elliptic partial differential equations cast into finite difference forms were solved by the TEACH code (Gosman and Pun, 1973), and the pressure field was computed by the SIMPLER method (Patankar, 1980). Various correlations for the dissipation rate of turbulent kinetic energy at the inlet were tested, and the relation yielding the best results was obtained as E= CμK1.5/(0.015de where de = 4 x hydraulic radius. Extensive comparisons have been made between the computed results using the proposed form of e at the inlet and experimental data taken from the literature. Much better predictions than previously possible have been obtained 相似文献
54.
三维目标在不同的视点下呈现不同的姿态 ,所得的二维视图也不尽相同 ,因此三维目标识别是一个较为复杂的问题 .为此提出了通过图象序列和图象序列之间的转移关系 ,根据胜者为王的原则来识别三维目标的方法 .该方法采用极指数栅格技术和傅立叶变换相结合得到目标的轮廓不变量 ;用神经网络结合方面图技术 ,通过识别运动目标图象序列来识别三维运动目标 ,实现了一个目标识别系统 .实验结果证明 ,此方法可以有效地用于三维运动目标的识别 相似文献
55.
56.
Hye Jin Hwang Sang Woo Kim Yu Mi Baek Sung Hak Lee Hee Sun Hwang Jong Won Yun 《Korean Journal of Chemical Engineering》2009,26(1):115-126
We established the gene expression profiling in streptozotocin (STZ)-induced diabetic rat liver in response to hypoglycemic
fungal polysaccharides (EPS), using oligonucleotide microarray analysis. Differentially regulated genes showing higher fold
change than 2 were identified and categorized through hierarchical clustering analysis. Among the 835 genes analyzed, 244
were up-regulated, while 321 were down-regulated after diabetes induction. Interestingly, many gene expressions altered after
STZ-treatment mimicked a normal rat liver by EPS therapy. Most of these genes included genes involving cell structure and
motility, immunity and defense, lipid, fatty acid and steroid metabolism, protein metabolism and modification, and signal
transduction. More importantly, we found a total of 36 genes that showed significant fold changes in their expression that
have not previously been examined in the context of diabetes. To validate the microarray results, we further confirmed the
gene expression patterns by RT-PCR using four genes of interest (carboxylesterase 2, stearoyl-coenzyme A desaturase 1, insulin-like
growth factor 1, and insulin-like growth factor binding protein 2). Taken together, EPS acted as a potent regulator of gene
expression for a wide variety of genes in diabetic rat liver. 相似文献
57.
Yeung Ho Park Seung Jun Kim Shin Choon Kang 《Korean Journal of Chemical Engineering》2000,17(1):81-85
The effects of the reaction variables in the operation of a fixed-bed reactor for oxidation ofo-xylene over V2O5/TiO2 catalysts were studied experimentally using a bench reactor. Reaction temperature, feed flow rate and feed concentration
ofo-xylene were found to have significant effects on the product distribution and the temperature profile in the reactor. Drastic
enhancements ofo-xylene oxidation reaction were observed at some conditions, which was ascribed to the effect of heat accumulated in the bed
and indicated a possible way to increase the productivity in the industrial condition.
This paper was presented at the 8th APCChE (Asia Pacific Confederation of Chemical Engineering) Congress held at Seoul between
August 16 and 19, 1999. 相似文献
58.
本文介绍一种新型的表面粗糙度测量仪,该具有精度高,便于携带,适应面广等特点。本文分析了该测量仪的测量原理,同时给出了该测量仪的电路结构,工作过程和技术指标。 相似文献
59.
60.
根据濮城西区沙二上2+3油藏层内矛盾突出的地质特点,提出并实施了远井调剖-近井封口的区块深部调剖试验,并将PI决策技术作为深部调剖选井、选剂、定量以及效果评价的理论基础,现场试验结果表明油藏的均质性明显增强,为厚层非均质油藏进入高含水开发提供了有益的借鉴。 相似文献