全文获取类型
收费全文 | 78590篇 |
免费 | 7845篇 |
国内免费 | 4090篇 |
专业分类
电工技术 | 4428篇 |
技术理论 | 1篇 |
综合类 | 4960篇 |
化学工业 | 13177篇 |
金属工艺 | 4554篇 |
机械仪表 | 5137篇 |
建筑科学 | 4849篇 |
矿业工程 | 1911篇 |
能源动力 | 2237篇 |
轻工业 | 7671篇 |
水利工程 | 1469篇 |
石油天然气 | 2965篇 |
武器工业 | 577篇 |
无线电 | 9872篇 |
一般工业技术 | 10806篇 |
冶金工业 | 3745篇 |
原子能技术 | 841篇 |
自动化技术 | 11325篇 |
出版年
2024年 | 392篇 |
2023年 | 1352篇 |
2022年 | 2477篇 |
2021年 | 3392篇 |
2020年 | 2532篇 |
2019年 | 2179篇 |
2018年 | 2578篇 |
2017年 | 2671篇 |
2016年 | 2680篇 |
2015年 | 3348篇 |
2014年 | 4155篇 |
2013年 | 5172篇 |
2012年 | 5696篇 |
2011年 | 6473篇 |
2010年 | 5630篇 |
2009年 | 5512篇 |
2008年 | 5147篇 |
2007年 | 4691篇 |
2006年 | 4313篇 |
2005年 | 3602篇 |
2004年 | 2693篇 |
2003年 | 2214篇 |
2002年 | 2044篇 |
2001年 | 1726篇 |
2000年 | 1437篇 |
1999年 | 1225篇 |
1998年 | 1057篇 |
1997年 | 793篇 |
1996年 | 692篇 |
1995年 | 516篇 |
1994年 | 446篇 |
1993年 | 332篇 |
1992年 | 254篇 |
1991年 | 190篇 |
1990年 | 156篇 |
1989年 | 138篇 |
1988年 | 97篇 |
1987年 | 79篇 |
1986年 | 74篇 |
1985年 | 42篇 |
1984年 | 38篇 |
1983年 | 32篇 |
1982年 | 29篇 |
1981年 | 23篇 |
1980年 | 24篇 |
1979年 | 22篇 |
1978年 | 18篇 |
1977年 | 23篇 |
1976年 | 32篇 |
1975年 | 13篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
2.
3.
为了避免回收单一钕铁硼废料中有价元素带来的操作复杂和资源浪费等问题,本研究采用共沉淀法共沉淀出钕铁硼废料中的有价元素Me(Nd,Pr,Co,Fe),制备可用于生产再生钕铁硼的原料;根据质量守恒和同时平衡原理,采用MATLAB软件建立Me(Nd,Pr,Co,Fe)-OH--NH3热力学模型,绘制lg[Me]-p H曲线模拟共沉淀工艺,并根据模拟结果确立了共沉淀工艺;模拟和实验的结果表明:根据lg[Me]-p H模拟结果可以确立一步共沉淀法的p H:6~10,Fe3+比Fe2+更易于沉淀完全;在上述条件下获得的共沉淀粉末主相均为Nd,Pr,Co,Fe的化合物,且有价元素的百分比含量均大于99.4%;其中,当p H值在8左右时回收率最高,在该条件下金属元素Me(Nd,Pr,Co,Fe)的沉淀效率分别为:98.7%,99.9%,93.6%,99.9%。该结果也表明共沉淀法工艺不仅高效,而且所制备的共沉淀粉末可以满足制备二次钕铁硼的需要。 相似文献
4.
Yao‐Min Hung Neng‐Chyan Huang Jyh‐Seng Wang Shue‐Ren Wann 《Hemodialysis international. International Symposium on Home Hemodialysis》2015,19(2):344-346
Cases of isolated hepatic tuberculosis (TB) are rare. The diagnosis is often delayed or missed because of nonspecific symptoms and laboratory findings. Besides, the disease is extremely rare even in a country where TB is an alarming public health problem. This report demonstrates the difficulty in correctly diagnosing local hepatic TB. We report the case of a 62‐year‐old male patient with end‐stage renal disease treated with hemodialysis, who developed 2 months of abdominal distension and general anorexia, with hyperechoic hepatic lesions on ultrasound. Computed tomography suspected multiple liver tumors. The liver biopsy finally led to the diagnosis of TB of the liver without other involvements. We conclude that isolated hepatic TB is one of the rare forms of extrapulmonary TB in dialysis patients. A greater awareness of this rare clinical entity may prevent needless surgical interventions. 相似文献
5.
Harshavardhan Mohan Jeong-Muk Lim Se-Won Lee Min Cho Yool-Jin Park Kamala-Kannan Seralathan Byung-Taek Oh 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2020,95(1):297-307
The cover image is based on the Research Article V2O5/RGO/Pt nanocomposite on oxytetracycline degradation and pharmaceutical effluent detoxification by Mohan, H et al., DOI: 10.1002/jctb.6238 .
6.
7.
8.
9.
Joo H. Kang Eujin Um Alexander Diaz Harry Driscoll Melissa J. Rodas Karel Domansky Alexander L. Watters Michael Super Howard A. Stone Donald E. Ingber 《Small (Weinheim an der Bergstrasse, Germany)》2015,11(42):5657-5666
Magnetic nanoparticles have been employed to capture pathogens for many biological applications; however, optimal particle sizes have been determined empirically in specific capturing protocols. Here, a theoretical model that simulates capture of bacteria is described and used to calculate bacterial collision frequencies and magnetophoretic properties for a range of particle sizes. The model predicts that particles with a diameter of 460 nm should produce optimal separation of bacteria in buffer flowing at 1 L h−1. Validating the predictive power of the model, Staphylococcus aureus is separated from buffer and blood flowing through magnetic capture devices using six different sizes of magnetic particles. Experimental magnetic separation in buffer conditions confirms that particles with a diameter closest to the predicted optimal particle size provide the most effective capture. Modeling the capturing process in plasma and blood by introducing empirical constants (ce), which integrate the interfering effects of biological components on the binding kinetics of magnetic beads to bacteria, smaller beads with 50 nm diameters are predicted that exhibit maximum magnetic separation of bacteria from blood and experimentally validated this trend. The predictive power of the model suggests its utility for the future design of magnetic separation for diagnostic and therapeutic applications. 相似文献
10.
Based on the phase transformation theories, especially the T0 concept of bainite transformation, alloy optimisation of bainitic steel with carbides has been carried out aiming at the produce of plastic mould with large cross-section. The effect of manganese and silicon on proeutectoid ferrite and bainite transformation is explored by dilatometric analysis, XRD and different microscopy techniques. The results show that after the alloy optimisation, the transformation of proeutectoid ferrite is suppressed and when the cooling rate is lower than 0·1°C?s??1, the new lower bainite transformation appears by decreasing carbon capacity of austenite and promoting carbide precipitation. Industrial production proves that the optimised alloy SDP1 can meet the demand for the plastic mould with the thickness of 1050?mm. 相似文献