首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   155935篇
  免费   18276篇
  国内免费   12000篇
电工技术   14265篇
技术理论   3篇
综合类   15346篇
化学工业   19635篇
金属工艺   10405篇
机械仪表   11074篇
建筑科学   11855篇
矿业工程   5466篇
能源动力   4530篇
轻工业   17140篇
水利工程   5822篇
石油天然气   4828篇
武器工业   2017篇
无线电   16982篇
一般工业技术   14687篇
冶金工业   6215篇
原子能技术   2599篇
自动化技术   23342篇
  2024年   940篇
  2023年   2586篇
  2022年   5624篇
  2021年   7340篇
  2020年   5438篇
  2019年   3971篇
  2018年   4198篇
  2017年   4780篇
  2016年   4404篇
  2015年   6701篇
  2014年   8341篇
  2013年   10203篇
  2012年   11997篇
  2011年   12417篇
  2010年   12004篇
  2009年   11580篇
  2008年   11895篇
  2007年   11615篇
  2006年   10193篇
  2005年   8303篇
  2004年   6421篇
  2003年   5086篇
  2002年   5599篇
  2001年   5101篇
  2000年   3452篇
  1999年   1744篇
  1998年   767篇
  1997年   634篇
  1996年   515篇
  1995年   466篇
  1994年   373篇
  1993年   264篇
  1992年   247篇
  1991年   187篇
  1990年   149篇
  1989年   121篇
  1988年   109篇
  1987年   73篇
  1986年   54篇
  1985年   40篇
  1984年   26篇
  1983年   20篇
  1982年   27篇
  1981年   24篇
  1980年   47篇
  1979年   31篇
  1978年   8篇
  1977年   11篇
  1959年   26篇
  1951年   24篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
Pleurotus eryngii, the second largest industrial cultivation mushroom in China, is usually cultivated on substrates mainly consisting of sawdust and corncob. In this study, experiments were performed to determine the effects of different carbon sources and C/N values on nonvolatile taste components of P. eryngii. The effects of different carbon sources on nonvolatile taste components levels revealed that sawdust was beneficial to high levels of crude protein, amino acids, 5′‐nucleotides and equivalent umami concentration, while corncob was beneficial to high contents of carbohydrate, polysaccharides and trehalose. At the similar C/N values, relatively higher sawdust content was beneficial to umami amino acid production, while relatively higher corncob content was beneficial to high contents of carbohydrate, polysaccharides and mannitol. Higher C/N value was beneficial to high levels of crude protein, amino acids, 5′‐nucleotides and equivalent umami concentration, while lower C/N value was beneficial to high contents of carbohydrate, polysaccharides and trehalose. These results provided information for P. eryngii fruit body industrial cultivation to obtain specific nonvolatile taste components with high levels.  相似文献   
2.
3.
田好敏  黄战峰 《煤炭技术》2015,34(1):365-368
对工业化进程中,即1949-2012年我国煤矿事故进行统计分析。建立煤矿安全以自然条件、安全管理和通风系统的3个层次及21个指标的综合评价体系,给出煤矿安全5个等级标准及相应的评价指标量值。应用可拓理论,以平顶山某煤矿为实例,进行计算分析,得出该煤矿等级为Ⅲ级,处于一般安全的状况,需要采取防范措施预防潜在危险因素。评价结果合理。  相似文献   
4.
5.
6.
从电焊机自身电气特点及建筑工地工作环境入手,探讨电焊机安全技术的实施方法。分析电焊机安全隐患及事故的分类以及电焊机在使用过程中产生危险的原因。介绍电焊机在安装以及作业过程中的安全措施。  相似文献   
7.
8.
SiC nano wires were fabricated on the silicon substrate dipped with a layer of Ni catalyst at 900 ℃ by gas pressure annealing processing. The morphologies and crystal structures were determined by scanning electron microscopy(SEM), transmission electron microscopy(TEM)and X-ray diffraction(XRD). The results show that the assynthesized nanowires are β-SiC single crystalline with diameter range of 50-100 nm, and length of tens of micron by directly annealing at 900 ℃. The SiC nano wires grow along the [111] direction with highly uniform morphology. And the possible growth mechanism of SiC nano wires is proposed.The present work provides an efficient strategy for the production of high-quality SiC nano wires.  相似文献   
9.
10.
This study evaluated several physical and sensory parameters of different types of cheese available in the Polish market. The measurements of textural properties were conducted in an Instron universal testing machine, while the colour properties of cheeses were measured using a Minolta chromameter. The chemical composition was determined by means of the near‐infrared spectroscopy (NIRs). Moreover, a trained sensory panel was invited to assess the cheese texture‐related properties. Generally, cheeses with reduced fat content were characterised by higher hardness, adhesiveness, cohesiveness and elasticity. Texture‐related parameters of cheese with canola oil were comparable to that of most of full‐fat cheeses. The correlation analysis between physical and sensory attributes related to cheese textural properties indicated the potential applications of TPA, shear and penetration tests (= 0.766, = 0.75 and = 0.765, respectively) for the evaluation of sensory properties related to the hardness. Meanwhile, the elasticity of cheese obtained from sensory evaluation was strongly correlated with the elasticity determined from the shear test (= 0.722) and moderately correlated with the elasticity from penetration test (= 0.588), indicating a need to refine the method of penetration test. In addition, cheeses exhibited higher meltability during convection heating at 230 °C than microwave heating. The values of meltability for cheese with reduced fat content were lower than those of full‐fat cheese.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号