全文获取类型
收费全文 | 1528篇 |
免费 | 93篇 |
国内免费 | 13篇 |
专业分类
电工技术 | 55篇 |
综合类 | 3篇 |
化学工业 | 331篇 |
金属工艺 | 33篇 |
机械仪表 | 57篇 |
建筑科学 | 21篇 |
能源动力 | 89篇 |
轻工业 | 73篇 |
水利工程 | 27篇 |
石油天然气 | 3篇 |
无线电 | 153篇 |
一般工业技术 | 359篇 |
冶金工业 | 135篇 |
原子能技术 | 4篇 |
自动化技术 | 291篇 |
出版年
2024年 | 11篇 |
2023年 | 32篇 |
2022年 | 63篇 |
2021年 | 70篇 |
2020年 | 70篇 |
2019年 | 59篇 |
2018年 | 85篇 |
2017年 | 90篇 |
2016年 | 95篇 |
2015年 | 62篇 |
2014年 | 67篇 |
2013年 | 126篇 |
2012年 | 80篇 |
2011年 | 79篇 |
2010年 | 81篇 |
2009年 | 75篇 |
2008年 | 39篇 |
2007年 | 40篇 |
2006年 | 43篇 |
2005年 | 33篇 |
2004年 | 24篇 |
2003年 | 30篇 |
2002年 | 27篇 |
2001年 | 20篇 |
2000年 | 17篇 |
1999年 | 15篇 |
1998年 | 20篇 |
1997年 | 27篇 |
1996年 | 17篇 |
1995年 | 10篇 |
1994年 | 12篇 |
1993年 | 11篇 |
1992年 | 7篇 |
1991年 | 8篇 |
1990年 | 8篇 |
1989年 | 8篇 |
1988年 | 8篇 |
1987年 | 8篇 |
1985年 | 2篇 |
1984年 | 6篇 |
1983年 | 3篇 |
1981年 | 7篇 |
1980年 | 7篇 |
1979年 | 8篇 |
1978年 | 2篇 |
1977年 | 4篇 |
1976年 | 3篇 |
1974年 | 3篇 |
1970年 | 4篇 |
1969年 | 3篇 |
排序方式: 共有1634条查询结果,搜索用时 15 毫秒
71.
Synthesis,Surface Properties and Effect of an Amino Acid Head Group of 11-(2-Methoxy-4-vinylphenoxy)undecanoicacid-Based Anionic Surfactants 下载免费PDF全文
Prabhakara Rao Darapureddi Rati Ranjan Nayak 《Journal of surfactants and detergents》2016,19(6):1133-1142
Our present research describes the surface properties of three biobased anionic surfactant synthesized from vinylguaiacol and 11-bromo undecanoic acid. To further improve its hydrophobicity and bioavailability, amino acid head group incorporation was carried out. All these synthesized compounds were thoroughly characterized using NMR and mass spectroscopy. The performance properties such as foaming, wetting, emulsification value and calcium tolerance were evaluated. The studied surfactants possess excellent emulsion stability and moderate calcium tolerance as compared to commercially available surfactant sodium lauryl sulfate (SLS). The micelle formation and the thermodynamics involved at the air–water interface were estimated from surface tension measurements. These surfactants showed a higher tendency towards adsorption at the air–water interface than micellization. Dynamic light scattering and steady state fluorescence anisotropy study were carried out to shed light on the bulk micellization properties of the synthesized surfactant. Along with spherical micelles of <5 nm size, larger aggregates (35–84 nm) were observed with higher anisotropy values. FESEM images further confirmed the larger spherical micelles formed by these surfactants. The surfactants formed chiral aggregates above the critical micelle concentration as indicated by circular dichroism spectra. These surfactants may be suitable candidates for additives to detergents to improve their calcium tolerance especially in the case of hard water. Furthermore, a low foaming ability along with high emulsion stability may find these surfactants to be better replacement of the conventional surfactant used as emulsifiers in many industrial applications. 相似文献
72.
Polyacrylonitrile (PAN), is an important base polymer to cast porous membranes. In this work, a detailed study of the effects of molecular weight of PAN homopolymer and its concentration on the cast membrane has been undertaken. The effects of molecular weight of additive polyethylene glycol (PEG) and its concentration have also been investigated. The membranes are cast using dimethyl formamide as solvent using phase inversion technique. They are characterized in terms of porosity, water permeability, molecular weight cut off, average pore diameter, contact angle, and tensile strength at breaking point. Fourier transform infrared spectroscopy and scanning electron microscopy are used to characterize the chemical and morphological changes of the membrane surface. Further studies have been considered to evaluate the antifouling property of various membranes using filtration of bovine serum albumin solution. Membrane modified by PEG 400 membrane shows an improved separation performance and antifouling characteristics. POLYM. ENG. SCI., 54:2375–2391, 2014. © 2013 Society of Plastics Engineers 相似文献
73.
Manas Sarkar Trinath Chowdhury Brajadulal Chattopadhyay Ratan Gachhui Saroj Mandal 《Journal of Materials Science》2014,49(13):4461-4468
The self-bioremediation in cementitious composite material is one of the most interesting avenues relating to damage management and self-life of constructions, which needs to be cogitated. The self-bioremediation of a microbial protein-impregnated cementitious material has been explored in this work. The bioremediase protein was isolated from a hot spring bacterium (BKH1) and incorporated at three different concentrations into commercial Pozzolana cements that are widely used for mortar sample preparation. Artificial cracks were generated within the mortar samples by applying partial breaking load (50 %) and the samples were cured under water for different days. Image analysis by Crackscope and microstructure analysis by field emission scanning electron microscope ascertained the formation of irregular crystalline healing material within the cracks of the test samples. X-ray diffractometer and energy dispersive spectra analyses confirmed that the irregular crystalline structures were due to the deposition of new silicate phase (Gehlenite) within the cracks. Increase of ultrasonic pulse velocity and compressive strength, augmentation of sulphate resistance, decrease of chloride permeability and water absorption capacity revealed that there were overall improvement of mechanical properties and durability of the protein-incorporated mortar samples compared to the control (without protein incorporation) mortar samples. This cost effective and eco-friendly self-bioremediation phenomenon observed in mortar is evolved due to the biosilicification activity of bioremediase protein when amended in mortar samples. The exceptional potential of the microbial bioremediase protein for self-bioremediation attribute may add a new dimension in self-healing construction technology in near future. 相似文献
74.
75.
Ranjan SHARMA Qiuwei WU Seung Tae CHA Kim Hφj JENSEN Tony Wederberg RASMUSSEN Jacob ΦSTERGAARD 《电力系统自动化》2015,39(3):14-22
To achieve active control of the AC voltage magnitude of wind power plant(WPP) collector network and improve the fault ride-through (FRT) capability,an FRT scheme based on feed forward DC voltage contr... 相似文献
76.
Kumar Manjesh Alok Anupam Das Manas 《Journal of Mechanical Science and Technology》2021,35(11):5151-5159
Journal of Mechanical Science and Technology - In this article, a new flow restrictor is utilized in the magnetorheological miniature gear-profile polishing (MRMGPP) method to ensure a consistent... 相似文献
77.
Nitroarenes as Antitubercular Agents: Stereoelectronic Modulation to Mitigate Mutagenicity 下载免费PDF全文
Dr. Sudhir Landge Dr. Vasanthi Ramachandran Dr. Anupriya Kumar Dr. João Neres Kannan Murugan Dr. Claire Sadler Dr. Mick D. Fellows Vaishali Humnabadkar Dr. Prakash Vachaspati Dr. Anandkumar Raichurkar Sreevalli Sharma Sudha Ravishankar Supreeth Guptha Dr. Vasan K. Sambandamurthy Dr. Tanjore S. Balganesh Dr. Bheemarao G. Ugarkar Dr. V. Balasubramanian Dr. Balachandra S. Bandodkar Dr. Manoranjan Panda 《ChemMedChem》2016,11(3):331-339
Nitroarenes are less preferred in drug discovery due to their potential to be mutagenic. However, several nitroarenes were shown to be promising antitubercular agents with specific modes of action, namely, nitroimidazoles and benzothiazinones. The nitro group in these compounds is activated through different mechanisms, both enzymatic and non‐enzymatic, in mycobacteria prior to binding to the target of interest. From a whole‐cell screening program, we identified a novel lead nitrobenzothiazole (BT) series that acts by inhibition of decaprenylphosphoryl‐β‐d ‐ribose 2′‐epimerase (DprE1) of Mycobacterium tuberculosis (Mtb). The lead was found to be mutagenic to start with. Our efforts to mitigate mutagenicity resulted in the identification of 6‐methyl‐7‐nitro‐5‐(trifluoromethyl)‐1,3‐benzothiazoles (cBTs), a novel class of antitubercular agents that are non‐mutagenic and exhibit an improved safety profile. The methyl group ortho to the nitro group decreases the electron affinity of the series, and is hence responsible for the non‐mutagenic nature of these compounds. Additionally, the co‐crystal structure of cBT in complex with Mtb DprE1 established the mode of binding. This investigation led to a new non‐mutagenic antitubercular agent and demonstrates that the mutagenic nature of nitroarenes can be solved by modulation of stereoelectronic properties. 相似文献
78.
79.
Hang Liu Xiaofeng Zhao Yuancheng Teng Yuxiang Li Xiayu Zheng Shanlin Wang Lang Wu Pritam Kumar Panda Rajeev Ahuja 《Journal of the American Ceramic Society》2022,105(7):4974-4985
LnPO4 · 0.667H2O rhabdophane has been considered as a potential material for the precipitation of actinides from radioactive waste liquid, owing to its outstanding characteristics of high actinide bearing and easy synthesis in acid solutions. However, a comprehensive understanding of the actinide occupation and the precipitation response of rhabdophane to remove actinides has yet to be established. In this study, the effect of ions concentration and pH values on the detailed precipitation reaction of CexNd1-xPO4 · 0.667H2O rhabdophane in acid solutions are systematically investigated. Some specific issues such as structural distortion and flexibility, and occupation mechanism are discussed by combining with experiments and density functional theory (DFT) calculation. The results reveal that ions concentration and pH values have a significant impact on the crystallization nucleation step before 12 h. The obtained removal rate of Nd3+ is more than 99% in pH 1–5 solutions with the ions concentration of 0.05–0.1 mol/L. Moreover, incorporating Nd in CePO4 · 0.667H2O rhabdophane will easily result in the lattice distortion in b-axis. DFT calculation and X-ray photoelectron spectroscopy (XPS) results reveal that Nd is preferentially incorporated in nonhydrated site to form a weaker binding energy of NdO8 polyhedron. 相似文献
80.
Silicon - Silicon (Si) and silver (Ag) doped amorphous carbon (a-C) thin film were deposited on chrome nitrided 316 LVM stainless steel using filtered cathodic vacuum arc (FCVA) deposition... 相似文献