全文获取类型
收费全文 | 115068篇 |
免费 | 8937篇 |
国内免费 | 4397篇 |
专业分类
电工技术 | 6209篇 |
技术理论 | 11篇 |
综合类 | 6892篇 |
化学工业 | 18926篇 |
金属工艺 | 6211篇 |
机械仪表 | 7060篇 |
建筑科学 | 9020篇 |
矿业工程 | 3215篇 |
能源动力 | 3252篇 |
轻工业 | 6856篇 |
水利工程 | 1837篇 |
石油天然气 | 6467篇 |
武器工业 | 779篇 |
无线电 | 14480篇 |
一般工业技术 | 14602篇 |
冶金工业 | 5926篇 |
原子能技术 | 1315篇 |
自动化技术 | 15344篇 |
出版年
2024年 | 203篇 |
2023年 | 1782篇 |
2022年 | 2425篇 |
2021年 | 4050篇 |
2020年 | 3229篇 |
2019年 | 2689篇 |
2018年 | 3099篇 |
2017年 | 3492篇 |
2016年 | 3115篇 |
2015年 | 4135篇 |
2014年 | 5245篇 |
2013年 | 6593篇 |
2012年 | 6969篇 |
2011年 | 7606篇 |
2010年 | 6602篇 |
2009年 | 6479篇 |
2008年 | 6481篇 |
2007年 | 6009篇 |
2006年 | 6333篇 |
2005年 | 5633篇 |
2004年 | 3844篇 |
2003年 | 3344篇 |
2002年 | 2942篇 |
2001年 | 2821篇 |
2000年 | 2920篇 |
1999年 | 3425篇 |
1998年 | 2948篇 |
1997年 | 2561篇 |
1996年 | 2290篇 |
1995年 | 1946篇 |
1994年 | 1566篇 |
1993年 | 1223篇 |
1992年 | 977篇 |
1991年 | 744篇 |
1990年 | 591篇 |
1989年 | 496篇 |
1988年 | 384篇 |
1987年 | 287篇 |
1986年 | 194篇 |
1985年 | 168篇 |
1984年 | 94篇 |
1983年 | 77篇 |
1982年 | 87篇 |
1981年 | 56篇 |
1980年 | 44篇 |
1979年 | 32篇 |
1978年 | 24篇 |
1977年 | 25篇 |
1976年 | 40篇 |
1973年 | 11篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
51.
A shale gas gathering and transportation pipeline in a good block in Sichuan Province started leaking after less than a year of operation. To investigate the causes of corrosion of the sulfate-reducing bacteria (SRB), optical microscopy, scanning electron microscopy, and X-ray diffraction were used to analyze the corrosion and perforation of the shale gas surface pipeline in conjunction with bacterial corrosion simulation experiments. The results showed that the pipeline material (L360N) conformed to the requirements of the American Petroleum Institute 5 L standard and that extracellular polymeric substances were present in the corrosion pits. The corrosion products mainly included FeCO3, FeS, CaCO3, MgCO3, and Fe mineralization. At 40°C, the uniform corrosion rate of L360N in the simulation experiment was 0.234 mm/a, and the local corrosion rate was 0.458 mm/a. SRB, saprophytes, and iron bacteria were detected in the on-site water medium and corrosion products, indicating that the main causes of shale gas pipeline corrosion are bacterial and CO2 corrosion. 相似文献
52.
Li-Xiang Wu Lin-Lin Zhu Wei-Ming Guo Shi-Kuan Sun Wen-Bin Niu Jia-Xiang Xue Jian-Han Zhai Hai-Bin Ma Rui-Lin Lin Hua-Tay Lin Kevin Plucknett Ye-Hong Liao Tong Liu Qi-Sen Ren 《Journal of the European Ceramic Society》2021,41(1):225-232
The joining of liquid-phase sintered SiC (LPS-SiC) ceramics was conducted using spark plasma sintering (SPS), through solid state diffusion bonding, with Ti-metal foil as a joining interlayer. Samples were joined at 1400 °C, under applied pressures of either 10 or 30 MPa, and with different atmospheres (argon, Ar, vs. vacuum). It was demonstrated that the shear strength of the joints increased with an increase in the applied joining pressure. The joining atmosphere also affected on both the microstructure and shear strength of the SiC joints. The composition and microstructure of the interlayer were examined to understand the mechanism. As a result, a SiC-SiC joining with a good mechanical performance could be achieved under an Ar environment, which in turn could provide a cost-effective approach and greatly widen the applications of SiC ceramic components with complex shape. 相似文献
53.
55.
With the evolution of video surveillance systems, the requirement of video storage grows rapidly; in addition, safe guards and forensic officers spend a great deal of time observing surveillance videos to find abnormal events. As most of the scene in the surveillance video are redundant and contains no information needs attention, we propose a video condensation method to summarize the abnormal events in the video by rearranging the moving trajectory and sort them by the degree of anomaly. Our goal is to improve the condensation rate to reduce more storage size, and increase the accuracy in abnormal detection. As the trajectory feature is the key to both goals, in this paper, a new method for feature extraction of moving object trajectory is proposed, and we use the SOINN (Self-Organizing Incremental Neural Network) method to accomplish a high accuracy abnormal detection. In the results, our method is able to shirk the video size to 10% storage size of the original video, and achieves 95% accuracy of abnormal event detection, which shows our method is useful and applicable to the surveillance industry. 相似文献
56.
57.
Yang Mengmeng Chen Zhaofeng Liu Tianlong Wu Qiong Yang Lixia 《Journal of Porous Materials》2022,29(2):523-530
Journal of Porous Materials - In recent years, oil spills and industrial organic pollutants have caused irreparable damage to the environment and biological ecosystems. Therefore, the treatment of... 相似文献
58.
Catalysis Letters - SBA-15 was modified via post-treatment with (NH4)2SiF6 and (NH4)3AlF6 solution (NSF-T and NAF-T) and applied as support of Pd catalysts for the hydrogenation of... 相似文献
59.
60.
以国外某高磷鲕状赤铁矿为研究对象进行脱磷研究,该高磷矿铁品位为55.81%,磷含量为0.72%,铁矿物主要为磁铁矿和赤铁矿,48.61%的磷存在于磷酸盐中,47.22%的磷分布于铁矿物中。研究了脱磷剂用量、秸秆炭用量、还原温度以及还原时间对粉末还原铁指标的影响。结果表明:无脱磷剂碳酸钙时,无法获得合格的指标;在碳酸钙用量为25%,秸秆炭用量为12.5%,还原温度1 200 ℃,还原时间为75 min,还原产品两段磨矿两段磁选的条件下,可获得铁品位、铁回收率以及磷含量分别为94.27%、87.34%以及0.077%的粉末还原铁,该产品可作为电炉炼钢的优质原料。不加添加剂时,部分含磷矿物被还原成单质磷进入到金属铁中,故粉末还原铁磷含量较高,当碳酸钙用量为25%时,含磷矿物的还原受到抑制而保留在脉石相中,可实现降磷目的,而还原时间过长时,磷仍在脉石相中,铁颗粒将部分含磷矿物包裹,磨矿难以分离,导致磷含量升高。 相似文献