全文获取类型
收费全文 | 3455篇 |
免费 | 101篇 |
国内免费 | 21篇 |
专业分类
电工技术 | 41篇 |
综合类 | 6篇 |
化学工业 | 859篇 |
金属工艺 | 124篇 |
机械仪表 | 80篇 |
建筑科学 | 48篇 |
矿业工程 | 3篇 |
能源动力 | 298篇 |
轻工业 | 184篇 |
水利工程 | 22篇 |
石油天然气 | 7篇 |
无线电 | 340篇 |
一般工业技术 | 804篇 |
冶金工业 | 470篇 |
原子能技术 | 25篇 |
自动化技术 | 266篇 |
出版年
2023年 | 37篇 |
2022年 | 67篇 |
2021年 | 107篇 |
2020年 | 86篇 |
2019年 | 85篇 |
2018年 | 142篇 |
2017年 | 77篇 |
2016年 | 83篇 |
2015年 | 77篇 |
2014年 | 112篇 |
2013年 | 218篇 |
2012年 | 159篇 |
2011年 | 195篇 |
2010年 | 158篇 |
2009年 | 143篇 |
2008年 | 122篇 |
2007年 | 118篇 |
2006年 | 93篇 |
2005年 | 78篇 |
2004年 | 67篇 |
2003年 | 81篇 |
2002年 | 51篇 |
2001年 | 46篇 |
2000年 | 38篇 |
1999年 | 68篇 |
1998年 | 154篇 |
1997年 | 99篇 |
1996年 | 93篇 |
1995年 | 50篇 |
1994年 | 53篇 |
1993年 | 53篇 |
1992年 | 37篇 |
1991年 | 40篇 |
1990年 | 34篇 |
1989年 | 34篇 |
1988年 | 27篇 |
1987年 | 38篇 |
1986年 | 39篇 |
1985年 | 28篇 |
1984年 | 36篇 |
1983年 | 40篇 |
1982年 | 24篇 |
1981年 | 19篇 |
1980年 | 23篇 |
1979年 | 32篇 |
1978年 | 22篇 |
1977年 | 16篇 |
1976年 | 23篇 |
1975年 | 9篇 |
1973年 | 11篇 |
排序方式: 共有3577条查询结果,搜索用时 16 毫秒
101.
R. Vijay M. Nagini S. S. Sarma M. Ramakrishna A. V. Reddy G. Sundararajan 《Metallurgical and Materials Transactions A》2014,45(2):777-784
Bulk samples of pure iron and yttria dispersed iron with and without titanium (i.e., Fe, Fe-Y2O3, and Fe-Y2O3-Ti) were prepared by hot extrusion of high-energy ball-milled powders. An examination of the microstructure using TEM revealed that the addition of titanium resulted in the reduction of the dispersoid size with a concomitant increase in the volume fraction of the dispersoids. As a result, Fe-Y2O3-Ti exhibited a substantial increase in hardness and tensile properties as compared to Fe and Fe-Y2O3. The higher hardness and strength of Fe-Y2O3-Ti is shown to be due to the presence of finer and higher number density of Y-Ti-O complex oxides. Dynamic strain aging in the temperature range of 423 K to 573 K (150 °C to 300 °C) was observed in all the compositions studied. 相似文献
102.
103.
Dr. Richa Sharma Tulika Srivastava Alka Raj Pandey Dr. Tripti Mishra Dr. Bhagyashri Gupta Dr. Sabbu Sathish Reddy Dr. Suriya P. Singh Dr. Tadigoppula Narender Aradhya Tripathi Dr. Balasubramanian Chandramouli Dr. Koneni V. Sashidhara Dr. Smriti Priya Dr. Niti Kumar 《ChemMedChem》2021,16(13):2146-2156
Defective protein folding and accumulation of misfolded proteins is associated with neurodegenerative, cardiovascular, secretory, and metabolic disorders. Efforts are being made to identify small-molecule modulators or structural-correctors for conformationally destabilized proteins implicated in various protein aggregation diseases. Using a metastable-reporter-based primary screen, we evaluated pharmacological chaperone activity of a diverse class of natural products. We found that a flavonoid glycoside ( C-10 , chrysoeriol-7-O-β-D-glucopyranoside) stabilizes metastable proteins, prevents its aggregation, and remodels the oligomers into protease-sensitive species. Data was corroborated with additional secondary screen with disease-specific pathogenic protein. In vitro and cell-based experiments showed that C-10 inhibits α-synuclein aggregation which is implicated in synucleinopathies-related neurodegeneration. C-10 interferes in its structural transition into β-sheeted fibrils and mitigates α-synuclein aggregation-associated cytotoxic effects. Computational modeling suggests that C-10 binds to unique sites in α-synuclein which may interfere in its aggregation amplification. These findings open an avenue for comprehensive SAR development for flavonoid glycosides as pharmacological chaperones for metastable and aggregation-prone proteins implicated in protein conformational diseases. 相似文献
104.
S. K. Srivastav A. Bhattacharya M. V. V. Kamaraju G. Sreenivasa Reddy A. K. Shrimal D. S. Mehta 《International journal of remote sensing》2013,34(17):3253-3267
This paper reports the results of a pilot study carried out in RajpuraDariba area, Rajasthan, for locating favourable zones of lead-zinc-copper (Pb-Zn-Cu) mineralization using remote sensing, Geographical Information System (GIS) and geostatistical modelling techniques. Remotely sensed data, both aerial and satellite, were used to update the existing geological map. ATLAS GIS software and multivariate geostatistical techniques were used to analyse and integrate different types of geological and geophysical datasets. The Favourability Index (FI) maps prepared during this study show the occurrence of three favourable zones for Pb-Zn-Cu mineralization. They are: (i) around and north of Rawan ka Khera; (ii) isolated spots between Ruppura and Bhupalsagar; and (iii) north of Dhani. Selective geochemical sampling and resistivity profiling carried out in these favourable zones indicated the presence of geochemical anomalies (anomalous concentrations of Zn and Cu) and low/moderate resistivity zones, respectively. Recent drilling carried out by the Department of Mines and Geology (DMG), Rajasthan, at about 2.5 km north of Rawan ka Khera (one of the predicted favourable zones) indicated evidence of Cu mineralization at a depth of about 70 m. 相似文献
105.
K. Srinivas P. Venugopal Reddy 《Journal of Superconductivity and Novel Magnetism》2014,27(11):2521-2538
With a view to investigate the influence of nanometric size on the structural, surface, and magnetic properties of nanocrystalline Ti0.95Co0.05O2-diluted magnetic semiconductors, prepared by a novel simple controllable peroxide-assisted reflux chemical route followed by annealing at different temperatures, a systematic investigation has been undertaken. Structural characterizations such as X-ray diffraction followed by Rietveld refinement, electron diffraction pattern, Fourier transform infrared, Raman scattering, and X-ray photoelectron spectroscopy (XPS) measurements have shown anatase phase formation in nanocrystalline Ti0.95Co0.05O2 without any additional impurity phases. The modified reflux chemical route was effective in obtaining pure phase Ti0.95Co0.05O2 nanoparticles. Surface morphological investigations by using transmission electron microscopy and atomic force microscopy measurements showed the predominant effect of random distribution of nanoparticles on the aggregation behavior and local microstructural changes. The deconvoluted XPS core level Co 2p spectral study manifested the oxidation state of Co as + 2 and is found to be stable with varying particle size and annealing temperature. The ferromagnetic behavior was investigated by vibrating sample magnetometer, magnetic force microscopy, and electron spin resonance measurements. These magnetization studies showed all the samples are ferromagnetic at room temperature without any magnetic clusters. The correlation between structure, surface condition of the nanoparticles and local electronic interactions, and magnetization of the samples was analyzed and explored the origin of ferromagnetism. 相似文献
106.
107.
108.
Chandhapuram Mounika Sunki Yella Reddy 《Journal of the American Oil Chemists' Society》2012,89(9):1691-1697
Structured lipids containing behenic and medium chain (MC) fatty acids were prepared from palm stearin using 1,3-specific lipase-catalyzed acidolysis. Incorporation of MC and behenic acids was affected by proportion of substrate, type of fatty acids, reaction time, addition of water and quantity of lipase. It was found that incorporation of caproic acid was less compared to other longer chain fatty acids. Caprylic, capric and behenic acids shared similar incorporation (up to 32 %), which increased with the amount of fatty acids added and the time of reaction. The incorporation of these acids increased with addition of 1 % moisture and the increasing amount of enzyme from 5 to 10 % at the beginning of the reaction. Incorporating behenic and MC fatty acids, reduced palmitic and oleic acids considerably from palm stearin, the extent being the same as those incorporated. However, the reduction of linoleic acid was marginal. The solid fats content of the modified palm stearin containing MC and behenic acids were reduced at all temperatures due to a reduction in higher molecular weight triglycerides and an increasing proportion of lower chain triglycerides. The modified products of palm stearin with added capric and behenic acids were similar to commercial bakery shortenings and those with added capric acid were like salad or cooking oils or butter in melting characteristics. 相似文献
109.
Tailoring the luminescence and photocatalytic activity of KMn4(PO4)3 by Anions (N3‐ and S2‐) doping 下载免费PDF全文
110.
Optimization of tensile properties thermoplastic blends from soy and biodegradable polyesters: Taguchi design of experiments approach 总被引:1,自引:0,他引:1
Soy meal-based biodegradable blends were prepared by melt extrusion process. The effects of denaturants, i.e., urea and sodium
sulfite and plasticizer (glycerol) and polyester type (polybutylene succinate, polycaprolactone, polybutylene adipate terephthalate)
on tensile strength and elongation at break were investigated using a Taguchi experimental design approach. The results showed
that the sodium sulfite had little or no effect on final properties of the blends. Also, biodegradable polyester type had
significant effect on the tensile strength and elongation at break of the blends prepared. The predicted values and experimental
were found to be in tune with each other. The chemical structure and morphology of the optimum sample was probed by FT-IR
spectroscopy and scanning electron microscopy (SEM). Also, the results provided an insight into how important the plasticization
and destructurization of soy protein to obtain the blends with desired mechanical properties. 相似文献