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   154850篇
  免费   14318篇
  国内免费   7656篇
电工技术   10255篇
技术理论   14篇
综合类   10369篇
化学工业   24627篇
金属工艺   8536篇
机械仪表   10135篇
建筑科学   12931篇
矿业工程   4427篇
能源动力   4583篇
轻工业   9972篇
水利工程   3204篇
石油天然气   7701篇
武器工业   1398篇
无线电   19293篇
一般工业技术   18003篇
冶金工业   7099篇
原子能技术   1811篇
自动化技术   22466篇
  2024年   524篇
  2023年   2493篇
  2022年   4518篇
  2021年   6814篇
  2020年   5134篇
  2019年   4096篇
  2018年   4584篇
  2017年   5088篇
  2016年   4599篇
  2015年   6506篇
  2014年   8534篇
  2013年   10246篇
  2012年   11462篇
  2011年   11929篇
  2010年   10628篇
  2009年   9992篇
  2008年   9463篇
  2007年   8832篇
  2006年   8412篇
  2005年   7136篇
  2004年   4736篇
  2003年   3769篇
  2002年   3343篇
  2001年   2898篇
  2000年   3026篇
  1999年   3224篇
  1998年   2784篇
  1997年   2238篇
  1996年   2044篇
  1995年   1695篇
  1994年   1408篇
  1993年   1017篇
  1992年   754篇
  1991年   625篇
  1990年   465篇
  1989年   412篇
  1988年   355篇
  1987年   193篇
  1986年   174篇
  1985年   111篇
  1984年   98篇
  1983年   62篇
  1982年   67篇
  1981年   61篇
  1980年   57篇
  1979年   48篇
  1978年   15篇
  1977年   34篇
  1976年   18篇
  1975年   15篇
排序方式: 共有10000条查询结果,搜索用时 281 毫秒
81.
82.
Yogurt preserves and enhances nutritional value of milk. In this study, we have compared several strains to determine the physicochemical, sensory, rheological and aroma characteristics of different yogurts. We used Lactobacillus gasseri LGZ 1029 (LG), commercial probiotic L. rhamnosus (LGG) and traditional fermentation strains Streptococcus thermophilus and L. bulgaricus (SL). Results showed that the flavour and texture characteristics of mixed-strain yogurts were obviously better than in single-strain yogurts. Addition of LG increased pseudoplastic behaviour, as shown by Herschel–Bulkley model analysis of rheological behaviour. The LG + SL group also had both the highest viscosity consistency index and thickening ability. In addition, a total of 57 volatile compounds were detected in yogurts and the fermentation with the addition of LG was mainly affected by ketones. Our study suggested that a yogurt with new attributes can be produced by using LGZ 1029.  相似文献   
83.
Waxy, normal and high-amylose maize starches were subjected to heat-moisture treatment (HMT) and then added to wheat flour (WF) in different ratios (1%, 5% and 10%). The properties of blends and their cooked noodles were studied to investigate the effects of HMT starches. The incorporation of HMT starch in WF led to an increase in swelling power, peak viscosity and breakdown and to a decrease in setback, thus inhibiting retrogradation, hence enhancing resultant noodle softness. Compared to the same addition ratio of native starch to WF, HMT starch led to higher tensile strength and extensibility in resultant noodles. WF with added HMT starch had higher resistant starch than with native starch. This study showed that addition of HMT maize starch has potential to bring nutritional benefits. However, it is necessary to select the proper blending ratio and amylose content of starch to add, in consideration of its effect on noodle quality.  相似文献   
84.
85.
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   
86.
87.
Sodalime float (SF) glass is widely used in our societies and industries. Hydrothermal corrosion method is one of the effective ways to prepare a superhydrophobic glass, but there is still lack of knowledge about hydrothermal corrosion behavior and mechanism of SF glass. We have hydrothermally treated SF glass at 180 °C for different time, and tried to reveal the aqueous corrosion process of SF glass. We have characterized the morphologies and chemical compositions of samples, and found that (1) the two sides of SF glass have different corrosion resistances, and (2) a multilayer structural coating with a nanoflake layer (Mg-rich gel layer), a nanowire layer (Ca-rich gel layer), and a porous layer (etched layer) is formed on the air-side of SF glass. Based on the experimental results, we have proposed an aqueous corrosion mechanism of SF glass. The insights of the hydrothermal corrosion behaviors and mechanism provide helpful guidelines to glass surface structural control and functionalization.  相似文献   
88.
Ti3C2Tx (MXene), a new kind of 2D ceramic nanosheets, is receiving more and more attention in the fields of medicine, biology, energy, electronics, etc. However, the preparation and application of MXene in hydrogel is still in its infancy period. Here, we review the latest progress (after 2018) related to MXene hydrogels in time. Aiming at the key issue of the dispersion stability of MXene in hydrogel systems, the preparation strategy, mechanism, advantages and disadvantages of MXene hydrogels are sorted out in detail, and the potential application prospects of MXene composite hydrogel are introduced. Finally, future viewpoints are put forward for the dispersion stability challenges that need solving in the design of MXene hydrogel.  相似文献   
89.
Analog Integrated Circuits and Signal Processing - Fault diagnosis of analog circuit is critical to improve safety and reliability in electrical systems and reduce losses. Traditional fault...  相似文献   
90.
针对领域自适应问题中源域和目标域的联合分布差异最小化问题,提出两阶段领域自适应学习方法.在第一阶段考虑样本标签和数据结构的判别信息,通过学习一个共享投影变换,使投影后的共享空间中边缘分布的差异最小.第二阶段利用源域标记数据和目标域非标记数据学习一个带结构风险的自适应分类器,不仅能最小化源域和目标域条件分布差异,还能进一步保持源域和目标域边缘分布的流形一致性.在3个基准数据集上的实验表明,文中方法在平均分类准确率和Kappa系数两项评价指标上均表现较优.  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