全文获取类型
收费全文 | 782篇 |
免费 | 46篇 |
国内免费 | 18篇 |
专业分类
电工技术 | 13篇 |
综合类 | 2篇 |
化学工业 | 203篇 |
金属工艺 | 13篇 |
机械仪表 | 22篇 |
建筑科学 | 23篇 |
矿业工程 | 1篇 |
能源动力 | 42篇 |
轻工业 | 63篇 |
水利工程 | 7篇 |
石油天然气 | 9篇 |
无线电 | 78篇 |
一般工业技术 | 175篇 |
冶金工业 | 36篇 |
原子能技术 | 7篇 |
自动化技术 | 152篇 |
出版年
2024年 | 5篇 |
2023年 | 23篇 |
2022年 | 48篇 |
2021年 | 84篇 |
2020年 | 37篇 |
2019年 | 38篇 |
2018年 | 48篇 |
2017年 | 39篇 |
2016年 | 45篇 |
2015年 | 33篇 |
2014年 | 31篇 |
2013年 | 69篇 |
2012年 | 43篇 |
2011年 | 40篇 |
2010年 | 29篇 |
2009年 | 43篇 |
2008年 | 19篇 |
2007年 | 23篇 |
2006年 | 19篇 |
2005年 | 10篇 |
2004年 | 10篇 |
2003年 | 6篇 |
2002年 | 12篇 |
2001年 | 13篇 |
2000年 | 7篇 |
1999年 | 8篇 |
1998年 | 12篇 |
1997年 | 6篇 |
1996年 | 4篇 |
1993年 | 2篇 |
1992年 | 3篇 |
1991年 | 3篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1988年 | 3篇 |
1987年 | 6篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1982年 | 3篇 |
1980年 | 2篇 |
1979年 | 3篇 |
1978年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1968年 | 1篇 |
1954年 | 1篇 |
排序方式: 共有846条查询结果,搜索用时 15 毫秒
81.
A model set of nonlinear electrostatic equations is analyzed critically; they have been presented earlier to study the short-scale auroral density cavities (SSADC) observed by Freja satellite. It is shown that electron inertial effect is not necessary to obtain solitary structure through electrostatic nonlinear equations. The ion streaming and direction of propagation of the structure seem to be the two parameters that can decide the width of the density cavity. 相似文献
82.
The weather in Baghdad, Iraq is hot dry in the summer while water is plentiful and cheap. These are conditions which encourage the use of evaporative cooling. A building with one space in it was used to test the effect of a roof pond which was ventilated mechanically for summer cooling. Thermal measurements were taken for the room in normal conditions without a pond, with a lone pond and no mechanical ventilation, and then finally with mechanically forced ventilation. The results showed a marked improvement in the space temperature with a significant reduction during the peak time outside temperatures at 3 O’clock reaching 6.0 °C between the room without the pond and with a ventilated one and 6.5° at 18:00 during peak inside temperatures. The study also showed that improvements would be better in real-life conditions where exterior wall area is less than the test room. 相似文献
83.
Adil Gani Shama Nazia Sajad A. Rather S.M. Wani Asima Shah Mudasir Bashir F.A. Masoodi Asir Gani 《LWT》2014
In this study red and white potato starches were treated with γ-irradiation of 0, 5, 10 and 20 kGy. Physicochemical, pasting and morphological properties of the irradiated starches were investigated. Apparent amylose content, pH, moisture, swelling power and syneresis decreased; whereas carboxyl content, water absorption capacity and solubility increased with increasing irradiation dose. Pasting properties also decreased significantly (p ≤ 0.05) upon increasing the irradiation dose. Observation under scanning electron microscope (SEM) showed surface cracking of the starch granules by γ-irradiation which increased with increase in irradiation dose. X-ray diffraction pattern remained the same upon irradiation but a decrease in relative crystallinity was observed with increasing irradiation dose. 相似文献
84.
Muhammad Saif Ullah Khan Zareen Akhter Touseef Naz Arshad Saleem Bhatti Humaira M Siddiqi Mohammad Siddiq Abbas Khan 《Polymer International》2013,62(2):319-334
Some novel ferrocene‐containing polyamide‐based block copolymer materials with telechelic polydimethylsiloxane oligomer and their organic analogues were prepared by solution‐phase polycondensation of ferrocene‐based organometallic and terephthaloyl‐ as well as isophthaloyl‐based organic acyl chlorides with a series of semi‐aromatic diamines having ether linkages together with variable aliphatic character. The corresponding polyamides of the synthesized materials, without polydimethylsiloxane segment, were also prepared for comparison of physicochemical properties. None of the synthesized organometallic and organic block copolymers along with their respective polyamides melted below 300 °C and their structural features were confirmed by their physical properties and spectroscopic studies. The weight‐average molecular weights and molecular parameters of all these materials were determined by the static laser light scattering technique. The materials were soluble in sulfuric acid and partially soluble in common organic solvents, and yet became readily soluble upon N‐trifluoroacetylation. The synthesized materials were further characterized by their water absorption characteristics, X‐ray diffraction studies and surface morphology (SEM and AFM) and thermal (DSC and TG) analyses, and their structure–property relationships were elucidated from these studies. The energies of pyrolysis for these materials were calculated by the Horowitz and Metzger method. © 2012 Society of Chemical Industry 相似文献
85.
Bhurchand Jain Gajendra K. Adil Usha Ananthakumar 《The International Journal of Advanced Manufacturing Technology》2014,71(9-12):2091-2105
Superior manufacturing capability provides long lasting competitive benefits to a company in the market. It is thus imperative to have an instrument to assess the manufacturing capability of companies. However, empirically tested and reliable tools for the purpose of evaluation of manufacturing capability along different decision areas are scarcely available in the literature. This paper develops questionnaires based on generally accepted principle of instrument design to assess the manufacturing capabilities along different decision areas for four categorization schemes of manufacturing decision areas reported in the literature. The reliability and validity of all four instruments are assessed through responses from managers of 32 manufacturing units and are found to be satisfactory for most of the factors. The criterion validity is found to be fairly good for all the four instruments. 相似文献
86.
N. P. Bharathi Nazia Umar Khan Sheikh Shreaz Athar Adil Hashmi 《Journal of Inorganic and Organometallic Polymers and Materials》2009,19(4):558-565
Zinc containing oil based polyesteramide resins were synthesized by condensation polymerization reaction between castor/soyabean
oil derived castor/soyabean fatty amide diol (HECA/HESA), Zn (OH)2 and adipic acid. The conventional spectroscopic techniques such as FTIR, 1HNMR, 13CNMR have been used to establish the structure of the polymers. Standard laboratory methods were used to study the physicochemical
characteristics like acid value, hydroxyl value, saponification value, iodine value, specific gravity, and viscosity. The
thermal behaviour of the polymers was analyzed by using thermo gravimetric analysis (TGA) and differential scanning calorimetry
(DSC). In vitro antifungal (anticandidial) activity of the polymers was studied against C. albicans ATCC-10261, C. glabrata ATCC-90030 and C. tropicalis ATCC-750, respectively. Antibacterial activity against Gram positive (S. subtillis) and Gram negative bacteria (E. coli and S. typhi) was also examined. For more accuracy, growth curve studies were carried out with the polymer SZ showing higher biological
activity against E. coli by using conventional spectrophotometer. The result showed that the polymers have potent anticandidial and antibacterial
activities. 相似文献
87.
88.
89.
Dr. Umberto Maria Battisti Dr. Chunxia Gao Oscar Nilsson Dr. Fady Akladios Dr. Aleksei Lulla Dr. Agnieszka Bogucka Dr. Amalyn Nain-Perez Dr. Liliana Håversen Dr. Woonghee Kim Prof. Jan Boren Prof. Marko Hyvönen Prof. Mathias Uhlen Prof. Adil Mardinoglu Prof. Morten Grøtli 《Chembiochem : a European journal of chemical biology》2023,24(1):e202200339
Enzymes are effective biological catalysts that accelerate almost all metabolic reactions in living organisms. Synthetic modulators of enzymes are useful tools for the study of enzymatic reactions and can provide starting points for the design of new drugs. Here, we report on the discovery of a class of biologically active compounds that covalently modifies lysine residues in human liver pyruvate kinase (PKL), leading to allosteric activation of the enzyme (EC50=0.29 μM). Surprisingly, the allosteric activation control point resides on the lysine residue K282 present in the catalytic site of PKL. These findings were confirmed by structural data, MS/MS experiments, and molecular modelling studies. Altogether, our study provides a molecular basis for the activation mechanism and establishes a framework for further development of human liver pyruvate kinase covalent activators. 相似文献
90.