全文获取类型
收费全文 | 61353篇 |
免费 | 3099篇 |
国内免费 | 1453篇 |
专业分类
电工技术 | 1667篇 |
技术理论 | 10篇 |
综合类 | 3260篇 |
化学工业 | 13699篇 |
金属工艺 | 6822篇 |
机械仪表 | 1646篇 |
建筑科学 | 8121篇 |
矿业工程 | 2001篇 |
能源动力 | 3123篇 |
轻工业 | 4824篇 |
水利工程 | 4917篇 |
石油天然气 | 2706篇 |
武器工业 | 161篇 |
无线电 | 1017篇 |
一般工业技术 | 4294篇 |
冶金工业 | 5664篇 |
原子能技术 | 499篇 |
自动化技术 | 1474篇 |
出版年
2024年 | 164篇 |
2023年 | 626篇 |
2022年 | 1490篇 |
2021年 | 1706篇 |
2020年 | 1553篇 |
2019年 | 1209篇 |
2018年 | 1186篇 |
2017年 | 1489篇 |
2016年 | 1485篇 |
2015年 | 1674篇 |
2014年 | 3127篇 |
2013年 | 3284篇 |
2012年 | 3829篇 |
2011年 | 4437篇 |
2010年 | 3703篇 |
2009年 | 3977篇 |
2008年 | 3106篇 |
2007年 | 4065篇 |
2006年 | 3865篇 |
2005年 | 3341篇 |
2004年 | 2855篇 |
2003年 | 2628篇 |
2002年 | 2130篇 |
2001年 | 1701篇 |
2000年 | 1388篇 |
1999年 | 1153篇 |
1998年 | 884篇 |
1997年 | 727篇 |
1996年 | 579篇 |
1995年 | 548篇 |
1994年 | 398篇 |
1993年 | 275篇 |
1992年 | 276篇 |
1991年 | 201篇 |
1990年 | 125篇 |
1989年 | 162篇 |
1988年 | 96篇 |
1987年 | 99篇 |
1986年 | 67篇 |
1985年 | 65篇 |
1984年 | 53篇 |
1983年 | 42篇 |
1982年 | 28篇 |
1981年 | 7篇 |
1980年 | 10篇 |
1979年 | 7篇 |
1966年 | 9篇 |
1965年 | 7篇 |
1964年 | 9篇 |
1959年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
41.
《International Journal of Hydrogen Energy》2021,46(75):37333-37339
Water electrolysis is an efficient approach for high-purity hydrogen production. However, the anodic sluggish oxygen evolution reaction (OER) always needs high overpotential and thus brings about superfluous electricity cost of water electrolysis. Therefore, exploiting highly efficient OER electrocatalysts with small overpotential especially at high current density will undoubtedly boost the development of industrial water electrolysis. Herein, we used a simple hydrothermal method to prepare a novel FeOOH–CoS nanocomposite on nickel foam (NF). The as-prepared FeOOH–CoS/NF catalyst displays an excellent OER performance with extremely low overpotentials of 306 and 329 mV at 500 and 1000 mA cm−2 in 1.0 M KOH, respectively. In addition, the FeOOH–CoS/NF catalyst can maintain excellent catalytic stability for more than 50 h, and the OER catalytic activity shows almost no attenuation no matter after 1000 repeated CV cycles or 50 h of stability test. The high catalytic activity and stability have exceeded most non-noble metal electrocatalysts reported in literature, which makes the FeOOH–CoS/NF composite catalyst have promising applications in the industrial water electrolysis. 相似文献
42.
Photocatalysts have attracted great research interest owing to their excellent properties and potential for simultaneously addressing challenges related to energy needs and environmental pollution. Photocatalytic particles need to be in contact with their respective media to exhibit efficient photocatalytic performances. However, it is difficult to separate nanometer-sized photocatalytic materials from reaction media later, which may lead to secondary pollution and a poor recycling performance. Hydrogel photocatalysts with a three-dimensional (3D) network structures are promising support materials for photocatalysts based on features such as high specific surface areas and adsorption capacities and good environmental compatibility. In this review, hydrogel photocatalysts are classified into two different categories depending on their elemental composition and recent progresses in the methods for preparing hydrogel photocatalysts are summarized. Moreover, current applications of hydrogel photocatalysts in energy conversion and environmental remediation are reviewed. Furthermore, a comprehensive outlook and highlight future challenges in the development of hydrogel photocatalysts are presented. 相似文献
43.
《International Journal of Hydrogen Energy》2020,45(15):8605-8617
Single phase, crystalline NaFeTiO4 with tunnel structure is prepared by a solid state method and explored as a novel photocatalyst for the first time. Structural, optical and morphological properties of NaFeTiO4 are investigated by various characterization techniques such as X-ray diffraction (XRD), scanning & transmission electron microscopy (SEM & TEM), Energy dispersive X-ray spectroscopy (EDS), N2 adsorption-desorption study (BET), UV-vis, X-ray photoelectron, X-ray absorption (UV-vis DRS, XPS and XANES) and photoluminescence (PL) spectroscopy. The interfacial charge transfer ability of the prepared n-type NaFeTiO4 was also investigated by transient photocurrent response and electrochemical impedence spectroscopy which proved to be an efficient tool for better understanding of electronic properties of NaFeTiO4. The photocatalytic efficiency of NaFeTiO4 is evaluated for decomposition of methylene blue (MB) and Rhodamine B (RhB) dyes as well as for H2 evolution through water splitting reaction under visible light. NaFeTiO4 exhibits efficient charge separation properties, excellent photocatalytic activities and reusability. 相似文献
44.
采油污水处理工艺探讨 总被引:3,自引:0,他引:3
针对采油污水的水质特点,以及其中有机污染物的组成,结合现有处理工艺,确定了以生化法降解有机污染物为核心的处理工艺,实现了达标排放,并对处理工艺适用性进行了分析。 相似文献
45.
太原精神病院污水处理系统改建为中水处理系统的工程设计 总被引:1,自引:0,他引:1
太原精神病医院将现有生活污水处理系统改建为中水回用系统,平均日处理水量100 m3.工程设计充分考虑了对原有设施的利用,生物处理单元采用生物接触氧化法.为减少污水提升次数,调节池设在生物处理单元之后.通过延长水力停留时间缓解水量、水质波动对沉淀、生物处理单元的不利影响,投入运行后效果良好. 相似文献
46.
Nicolas Guerda; DeSilva Angela M.; Grey Kathleen S.; Gonzalez-Eastep Diana 《Canadian Metallurgical Quarterly》2006,37(6):702
Currently, ethnic and racial minority individuals represent a large proportion of the U.S. population, and researchers expect that they will represent the majority of the population by 2050. This shift in U.S. demographics calls for a greater awareness and integration of cultural issues into the assessment and treatment of ethnically and linguistically diverse clients. This article examines the unique beliefs and manifestations of illnesses among Haitians in connection with the American Psychological Association's (APA, 2002) Multicultural Guidelines. The authors use a common culture-bound syndrome, Séizisman, to illustrate the cultural beliefs, assessment, and treatment of illnesses among Haitians. In so doing, they demonstrate how to incorporate the APA Multicultural Guidelines into treatment with clients of diverse cultural and racial backgrounds. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
47.
轻质滤料滤池的试验与研究 总被引:1,自引:0,他引:1
轻质滤料滤池是以比水密度略小的滤料为滤床的滤池,通过以净水厂的原水和污水处理厂的二级处理出水为过滤试验对象,所取得的结果表明:下向流轻质滤料滤池对浊度和悬浮固体(SS)的去除率分别可以达到80%和45%,而滤床的水头损失不超过15cm。因此轻质滤料滤池可以以预过滤的形式配置在过滤处理的净水和污水的处理工艺中。 相似文献
48.
炼油达标污水回用处理试验研究 总被引:1,自引:0,他引:1
采用曝气生物滤池、多介质过滤、超滤、反渗透工艺,对炼油达标外排污水进行回用处理中试试验。结果表明,曝气生物滤池对油、COD和浊度去除效果良好,超滤、反渗透膜化学清洗周期达到 2个月以上,脱盐率稳定在98%以上,产水品质达到回用要求。 相似文献
49.
采用四组分法从辽河减压渣油中分离出胶质、沥青质,分别考察了它们在分散型催化剂作用下的临氢热反应行为。结果表明,胶质、沥青质一方面要裂化生成较轻的产物;另一方面也要发生缩合反应生成较重的反应产物以及甲苯不溶物。渣油在临氢热反应过程中,沥青质是生焦的主要来源,其次才是胶质。比较了热反应生成的沥青质与原生沥青质之间以及热反应生成的胶质与原生胶质之间化学组成的区别,结果表明,反应生成的沥青质和胶质较原生的沥青质和胶质分子结构缩合程度高,并且反应苛刻度越高,缩合程度也越高。 相似文献
50.