全文获取类型
收费全文 | 4426篇 |
免费 | 480篇 |
国内免费 | 106篇 |
专业分类
电工技术 | 25篇 |
综合类 | 338篇 |
化学工业 | 1570篇 |
金属工艺 | 59篇 |
机械仪表 | 14篇 |
建筑科学 | 255篇 |
矿业工程 | 131篇 |
能源动力 | 149篇 |
轻工业 | 1760篇 |
水利工程 | 72篇 |
石油天然气 | 358篇 |
武器工业 | 3篇 |
无线电 | 15篇 |
一般工业技术 | 118篇 |
冶金工业 | 99篇 |
原子能技术 | 7篇 |
自动化技术 | 39篇 |
出版年
2024年 | 46篇 |
2023年 | 102篇 |
2022年 | 206篇 |
2021年 | 257篇 |
2020年 | 243篇 |
2019年 | 242篇 |
2018年 | 186篇 |
2017年 | 194篇 |
2016年 | 215篇 |
2015年 | 170篇 |
2014年 | 232篇 |
2013年 | 245篇 |
2012年 | 281篇 |
2011年 | 292篇 |
2010年 | 201篇 |
2009年 | 209篇 |
2008年 | 147篇 |
2007年 | 227篇 |
2006年 | 208篇 |
2005年 | 197篇 |
2004年 | 162篇 |
2003年 | 143篇 |
2002年 | 154篇 |
2001年 | 94篇 |
2000年 | 74篇 |
1999年 | 41篇 |
1998年 | 25篇 |
1997年 | 34篇 |
1996年 | 28篇 |
1995年 | 24篇 |
1994年 | 15篇 |
1993年 | 20篇 |
1992年 | 13篇 |
1991年 | 16篇 |
1990年 | 7篇 |
1989年 | 10篇 |
1988年 | 7篇 |
1987年 | 8篇 |
1986年 | 2篇 |
1985年 | 8篇 |
1984年 | 5篇 |
1983年 | 4篇 |
1982年 | 2篇 |
1981年 | 3篇 |
1980年 | 8篇 |
1977年 | 1篇 |
1951年 | 4篇 |
排序方式: 共有5012条查询结果,搜索用时 46 毫秒
101.
Xiuping Zhu Bruce E. Logan 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2014,89(3):471-474
Non‐corrosive, carbon‐based materials are usually used as anodes in microbial fuel cells (MFCs). In some cases, however, metals have been used that can corrode (e.g. copper) or that are corrosion resistant (e.g. stainless steel, SS). Corrosion could increase current through galvanic (abiotic) current production or by increasing exposed surface area, or decrease current due to generation of toxic products from corrosion. In order to directly examine the effects of using corrodible metal anodes, MFCs with Cu were compared with reactors using SS and carbon cloth anodes. MFCs with Cu anodes initially showed high current generation similar to abiotic controls, but subsequently they produced little power (2 mW m‐2). Higher power was produced with microbes using SS (12 mW m‐2) or carbon cloth (880 mW m‐2) anodes, with no power generated by abiotic controls. These results demonstrate that copper is an unsuitable anode material, due to corrosion and likely copper toxicity to microorganisms. © 2013 Society of Chemical Industry 相似文献
102.
Effect of ammonia inhibition on microbial community dynamic and process functional resilience in mesophilic methane fermentation of chicken manure 下载免费PDF全文
103.
104.
Julio Valdivia-Silva Jaciel Medina-Tamayo Eduardo A. Garcia-Zepeda 《International journal of molecular sciences》2015,16(6):12958-12985
Chemokines are a burgeoning family of chemotactic cytokines displaying a broad array of functions such as regulation of homeostatic leukocyte traffic and development, as well as activating the innate immune system. Their role in controlling early and late inflammatory stages is now well recognized. An improper balance either in chemokine synthesis or chemokine receptor expression contributes to various pathological disorders making chemokines and their receptors a useful therapeutic target. Research in this area is progressing rapidly, and development of novel agents based on chemokine/chemokine receptors antagonist functions are emerging as attractive alternative drugs. Some of these novel agents include generation of chemokine-derived peptides (CDP) with potential agonist and antagonist effects on inflammation, cancer and against bacterial infections. CDP have been generated mainly from N- and C-terminus chemokine sequences with subsequent modifications such as truncations or elongations. In this review, we present a glimpse of the different pharmacological actions reported for CDP and our current understanding regarding the potential use of CDP alone or as part of the novel therapies proposed in the treatment of microbial infections and cancer. 相似文献
105.
高分子铁盐混凝剂的开发与应用进展 总被引:24,自引:3,他引:24
高分子铁盐混凝剂是一类高效水处理剂,也是较广泛应用的絮凝剂,作者简要地阐述了近年来我国高分子铁盐混凝剂的开发及应用领域的研究进展情况。 相似文献
106.
Suyanee Nachaiyasit David C. Stuckey 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1997,69(2):276-284
The effect of a decrease in operating temperature on the performance of two 10 dm3 anaerobic baffled reactors (ABR) was examined in terms of steady state chemical oxygen demand (COD) removal efficiency. To minimise variations, and have a totally biodegradable feed, a synthetic carbohydrate (sucrose)–protein (meat extract) substrate was used. The reactors were operated at 20 h hydraulic retention time (HRT), 4 g dm−3 COD, and 35°C as a base-line condition. Because of their different histories, the reactors responded differently to a decrease in operating temperature to 25°C. Reactor 1 remained stable at 97% COD removal, whereas Reactor 2 decreased to 93% removal, but rose to 97% after adding an effluent recycle of 0·25. At 15°C, the efficiency of Reactor 1 dropped to 75%, while the removal of Reactor 2 declined to 83%, and no improvement in efficiency occurred with an effluent recycle at 0·25. At 25°C, the decreased rate of catabolism of the slow-growing syntrophs and methanogens resulted in a shift of the volatile fatty acids (VFA) peak to the second compartment. However, the biomass present in the reactor prevented VFAs breaking through in the effluent. Nevertheless, at 15°C VFAs were present in the effluent, perhaps due to the lower rates of metabolism and an increase in the Ks for VFAs. Finally, at 15°C part of the increase in the effluent COD was due to the enhanced production of soluble microbial products (SMP), or a decrease in their metabolism, with these compounds constituting some 10% of the inlet COD. © 1997 SCI. 相似文献
107.
108.
经离心、乙醇沉淀、透析、凝胶过滤层析及冷冻干燥后获得纯化的微生物絮凝剂MBFA1,并利用紫外、红外、凝胶渗透色谱、气质色谱进行絮凝剂的组分、含量、分子量和结构的分析。结果表明,纯化后的MBFA1为淡黄色,主要成分为多糖类物质,其中多糖含量为91.2%,蛋白质为0.59%。元素分析显示MBFA1中C、H、N、S的含量分别为33.41%、7.69%、9.63%和0.39%。采用凝胶色谱法测得MBFA1的重均相对分子质量约为1.38×104。紫外光谱显示,MBFA1在199 nm处出现了吸收峰值,为多糖的特征峰。红外光谱显示MBFA1中含有羟基、氨基、羧基、氢键、硫酸根等对絮凝有利的基团。GC-MS分析MBFA1主要的单糖构成为D-葡萄糖,并含有少量的D-阿拉伯糖及D-甘露糖,其摩尔比约为100.7∶1∶8.2。 相似文献
109.
本文阐述了灰霉病病原菌的生物学特性;介绍了国内外用于灰霉病生物防治的微生物种类及其生防机制的研究进展;同时讨论了目前灰霉病等植物病害生防工作存在的主要问题及今后研究的重点;并对微生物防治的应用前景进行了展望。 相似文献
110.
以辣椒残渣,阳离子醚化剂,环氧丙基三甲基氯化胺为原料,通过干法合成了一种季胺型阳离子絮凝剂。采用正交实验方法,确定了制备的最佳工艺条件:辣椒与阳离子醚化剂物质的量比1:3,反应温度80℃,反应时间3h。实验用高岭土溶液模拟生活废水,加入自制絮凝剂检测凝剂性能,在此条件下合成的阳离子辣椒絮凝剂的除浊率是88%。 相似文献