全文获取类型
收费全文 | 61145篇 |
免费 | 7699篇 |
国内免费 | 4522篇 |
专业分类
电工技术 | 5284篇 |
技术理论 | 2篇 |
综合类 | 6656篇 |
化学工业 | 7976篇 |
金属工艺 | 4048篇 |
机械仪表 | 3894篇 |
建筑科学 | 4681篇 |
矿业工程 | 2382篇 |
能源动力 | 1866篇 |
轻工业 | 6788篇 |
水利工程 | 1890篇 |
石油天然气 | 2378篇 |
武器工业 | 754篇 |
无线电 | 6041篇 |
一般工业技术 | 5495篇 |
冶金工业 | 2803篇 |
原子能技术 | 1313篇 |
自动化技术 | 9115篇 |
出版年
2025年 | 5篇 |
2024年 | 921篇 |
2023年 | 1012篇 |
2022年 | 2038篇 |
2021年 | 2571篇 |
2020年 | 1933篇 |
2019年 | 1469篇 |
2018年 | 1571篇 |
2017年 | 1776篇 |
2016年 | 1675篇 |
2015年 | 2469篇 |
2014年 | 3036篇 |
2013年 | 3818篇 |
2012年 | 4423篇 |
2011年 | 4591篇 |
2010年 | 4365篇 |
2009年 | 4288篇 |
2008年 | 4382篇 |
2007年 | 4333篇 |
2006年 | 3849篇 |
2005年 | 3148篇 |
2004年 | 2802篇 |
2003年 | 2734篇 |
2002年 | 3302篇 |
2001年 | 2821篇 |
2000年 | 1578篇 |
1999年 | 809篇 |
1998年 | 266篇 |
1997年 | 214篇 |
1996年 | 205篇 |
1995年 | 180篇 |
1994年 | 155篇 |
1993年 | 95篇 |
1992年 | 97篇 |
1991年 | 71篇 |
1990年 | 54篇 |
1989年 | 46篇 |
1988年 | 31篇 |
1987年 | 39篇 |
1986年 | 31篇 |
1985年 | 24篇 |
1984年 | 18篇 |
1983年 | 15篇 |
1982年 | 7篇 |
1981年 | 9篇 |
1980年 | 18篇 |
1979年 | 15篇 |
1976年 | 7篇 |
1959年 | 9篇 |
1951年 | 12篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
101.
肖晔 《中国制造业信息化》2009,(2)
介绍了HSPA网络及其技术特点,阐明了在中国3G时代到来之际发展HSPA网络的重要性和必要性,指出了建设高质量的HSPA网络的关键在于提高HSPA整体的吞吐速率,从组网策略、功率分配、码字分配、调度算法选择等13个方面,对如何提高HSPA吞吐速率的问题提出了整套建议. 相似文献
102.
对NiMnCo触媒合金加工过程中存在的热轧开裂问题作了研究。结果表明 :NiMnCo合金的热轧开裂为晶间断裂 ,裂纹沿晶界扩展。造成合金热塑性降低的原因是溶质 (杂质 )原子在晶界的偏析以及第二相夹杂物的存在。通过原材料处理及强化合金熔炼工艺可消除热轧裂纹的产生。 相似文献
103.
The electrochemical corrosion behavior of 300M ultra high strength steel in chloride containing environment was investigated by potentiodynamic polarization technique, electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM). The results show that uniform corrosion occurs on 300M steel during the electrochemical measurements because no anodic passivation phenomenon is observed on polarization curves within the measurement range. The tests also show that 300M steel is highly susceptible to chloride containing solution, which is characterized by corrosion current density increasing with the addition of chlorides, and corrosion potential shifting towards positive direction and corrosion resistance decreasing, positively suggesting that chloride ions speed up the corrosion rate of 300M steel. Meanwhile corrosion products on the 300M steel surface formed during the salt spray test are too loose and porous to effectively slow down the corrosion rate. Additionally, a schematic structure of uniform corrosion mechanism can explain that 300M steel has better property of stress corrosion cracking (SCC) resistance than stainless steels. 相似文献
104.
Large-scale single-crystalline SnO2 nanocauliflowers were successfully synthesized using a hydrothermal growth method without any template. The samples were
characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy
(EDS), transmission electron microscopy (TEM), and selected area electron diffraction (SAED). FE-SEM images show that the
as-grown SnO2 nanocauliflowers are constructed of tetragonal prisms with a width of 500–600 nm. XRD, EDS, and SAED results indicate that
the as-grown SnO2 nanocauliflowers are single crystalline with the tetragonal rutile crystalline structure. The growth mechanism of SnO2 nanocauliflowers is also preliminarily discussed on the basis of different Sn(OH)62− concentrations, and it is found that Sn(OH)62− concentration plays an important role in determining the shape of the prepared SnO2. Room temperature photoluminescence was further carried out on SnO2 nanocauliflowers to investigate their optical properties. An intense blue luminescence centered at a wavelength of 424 nm
is observed in the as-grown SnO2 nanocauliflowers. 相似文献
105.
106.
This paper describes film cooling characteristics of the novel combined configuration employing interrupted slot and trench holes on a vane endwall.Interrupted ... 相似文献
107.
108.
Mei Li Jiaojiao Zheng Tian Wu Yulin He Jing Guo Jiao Xu Chuanzhou Gao Shuxian Qu Qianyi Zhang Jiayu Zhao Wei Cheng 《International journal of molecular sciences》2022,23(8)
TRPV4 (transient receptor potential vanilloid 4), a calcium permeable TRP ion channel, is known to play a key role in endocytosis. However, whether it contributes to exocytosis remains unclear. Here, we report that activation of TRPV4 induced massive exocytosis in both melanoma A375 cell and heterologous expression systems. We show here that, upon application of TRPV4-specific agonists, prominent vesicle priming from endoplasmic reticulum (ER) was observed, followed by morphological changes of mitochondrial crista may lead to cell ferroptosis. We further identified interactions between TRPV4 and folding/vesicle trafficking proteins, which were triggered by calcium entry through activated TRPV4. This interplay, in turn, enhanced TRPV4-mediated activation of folding and vesicle trafficking proteins to promote exocytosis. Our study revealed a signaling mechanism underlying stimulus-triggered exocytosis in melanoma and highlighted the role of cellular sensor TRPV4 ion channel in mediating ferroptosis. 相似文献
109.
由于需求的多变性、模糊性以及多样性的特点,使得新产品创意与市场需求之间存在一定的差距.为了实现新产品概念商业化的成功,产品创意必须再次回到市场需求问题上来,并经过需求评价等方法进一步完善与发展.本文结合设计实例,阐述了快速原型在问题评价时激发创造性思维中所起到的作用. 相似文献
110.