全文获取类型
收费全文 | 3776篇 |
免费 | 240篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 57篇 |
化学工业 | 881篇 |
金属工艺 | 122篇 |
机械仪表 | 67篇 |
建筑科学 | 91篇 |
矿业工程 | 12篇 |
能源动力 | 129篇 |
轻工业 | 494篇 |
水利工程 | 11篇 |
石油天然气 | 9篇 |
无线电 | 85篇 |
一般工业技术 | 627篇 |
冶金工业 | 1051篇 |
原子能技术 | 22篇 |
自动化技术 | 361篇 |
出版年
2023年 | 26篇 |
2022年 | 60篇 |
2021年 | 107篇 |
2020年 | 85篇 |
2019年 | 64篇 |
2018年 | 154篇 |
2017年 | 155篇 |
2016年 | 158篇 |
2015年 | 117篇 |
2014年 | 151篇 |
2013年 | 255篇 |
2012年 | 174篇 |
2011年 | 223篇 |
2010年 | 146篇 |
2009年 | 123篇 |
2008年 | 115篇 |
2007年 | 119篇 |
2006年 | 70篇 |
2005年 | 51篇 |
2004年 | 55篇 |
2003年 | 45篇 |
2002年 | 44篇 |
2001年 | 24篇 |
2000年 | 18篇 |
1999年 | 17篇 |
1998年 | 175篇 |
1997年 | 197篇 |
1996年 | 133篇 |
1995年 | 91篇 |
1994年 | 47篇 |
1993年 | 63篇 |
1992年 | 17篇 |
1991年 | 9篇 |
1990年 | 15篇 |
1989年 | 10篇 |
1988年 | 14篇 |
1987年 | 11篇 |
1986年 | 9篇 |
1985年 | 14篇 |
1984年 | 31篇 |
1983年 | 19篇 |
1982年 | 39篇 |
1981年 | 45篇 |
1980年 | 54篇 |
1979年 | 25篇 |
1978年 | 37篇 |
1977年 | 108篇 |
1976年 | 234篇 |
1975年 | 13篇 |
1973年 | 11篇 |
排序方式: 共有4019条查询结果,搜索用时 15 毫秒
1.
Prof. Andrea Baier Dr. Anne Kokel Dr. William Horton Ewa Gizińska Dr. Garima Pandey Prof. Ryszard Szyszka Prof. Béla Török Prof. Marianna Török 《ChemMedChem》2021,16(12):1927-1932
A set of novel hydrazone derivatives were synthesized and analyzed for their biological activities. The compounds were tested for their inhibitory effect on the phosphorylating activity of the protein kinase CK2, and their antioxidant activity was also determined in three commonly used assays. The hydrazones were evaluated for their radical scavenging against the DPPH, ABTS and peroxyl radicals. Several compounds have been identified as good antioxidants as well as potent protein kinase CK2 inhibitors. Most hydrazones containing a 4-N(CH3)2 residue or perfluorinated phenyl rings showed high activity in the radical-scavenging assays and possess nanomolar IC50 values in the kinase assays. 相似文献
2.
Lindsey Yue Alicia Bayon Wojciech Lipiński 《American Institute of Chemical Engineers》2021,67(8):e17267
The effects of particle size and carbon dioxide concentration on chemical conversion in engineered spherical particles undergoing calcium oxide looping are investigated. Particles are thermochemically cycled in a furnace under different carbon dioxide concentrations. Changes in composition due to chemical reactions are measured using thermogravimetric analysis. Gas composition at the furnace exit is evaluated with mass spectroscopy. A numerical model of thermal transport phenomena developed previously is adapted to match the physical system investigated in the present study. The model is used to elucidate effects of reacting medium characteristics on particle temperature and reaction extent. Experimental and numerical results show that (1) an increase in particle size results in a decrease in carbonation extent, and (2) the carbonation step consists of fast and slow reaction regimes. The reaction rates in the fast and slow carbonation regimes increase with increasing carbon dioxide concentration. The effect of carbon dioxide concentration and the distinction between the fast and slow regimes become more pronounced with increasing particle size. 相似文献
3.
Babilas R. Łoński W. Młynarek K. Bajorek A. Radoń A. 《Metallurgical and Materials Transactions A》2020,51(8):4215-4227
Metallurgical and Materials Transactions A - The influence of the chemical composition on the crystallization process, amorphous phase formation, and the anticorrosion properties of Al-Zr-Ni-Fe-Y... 相似文献
4.
5.
A hybrid fluidized-bed bioreactor for water purification was proposed and analyzed. It is a novel type of bioreactor characterized by hitherto unknown stationary and dynamic features. Steady-state characteristics of this hybrid bioreactor with external liquid circulation are presented. A quantitative analysis of steady-state properties of the bioreactor was performed with the aid of an original mathematical model developed for a double-substrate aerobic microbiological process. A steady-state analysis of aerobic processes characterized by different oxygen demand was performed. The effect of essential parameters was evaluated, including carbonaceous substrate concentration in the feed stream to the apparatus, aeration intensity, total residence time of a liquid in the bioreactor, and height of the bed of fine carrier particles. 相似文献
6.
Analysis of non-stationary electrochemical oscillations emerges utilization of the techniques allowing an observation of time evolution of their parameters such as instantaneous frequency, amplitude or frequency band. An algorithm of extraction of these parameters can be based on one of linear or quadratic time-frequency representations of oscillations record. In this paper, the authors present representatives of such transformations (Choi-Williams and Cone-shaped) originating from one of the most popular joint time-frequency energy distribution—Wigner-Ville distribution. Short introduction to the mathematics of the topic discussed is provided, then the authors present an example of application in the analysis of current oscillations of copper dissolution process. 相似文献
7.
A Sawicka-Grzelak F Meisel-Miko?ajczyk SM S?otwińska M Wierzbicka 《Canadian Metallurgical Quarterly》1997,49(1-2):95-100
The aim of study was the evaluation of periodontal pockets microflora in patients with advanced periodontitis. From each subject 16-20 samples were taken using paper points. Pooled sample after 60 s. mixing was serially diluted in reduced BHI. For total cell counts and for the isolation of black pigmented anaerobes Brucella agar supplemented with 5% sheep blood, hemin, menadione, with and without Kanamycin-Vancomycin mixture and BM agar plates were used. For isolation of A. actinomycetemcomitans TSBV agar plates were used. Cultures were incubated in anaerobic chamber at 37 degrees C for 7 days and TSBV agar plates in an atmosphere of 95% air-5% CO2 at 37 degrees C for 5 days. Microorganisms were identified by Gram staining, colony morphology, fluorescence in UV-light, haemagglutination of 3% sheep erythrocytes, fermentation of sugars, production of indole, urease (API 20A), specific enzymes (Rapid ID 32A). Twenty seven subjects with clinically recognized periodontitis were examined. Microorganisms important in periodontitis were isolated from periodontal pockets of almost all examined subjects. The number of bacteria obtained from the sample of one patient ranged from 1 x 10(4) CFU/ml to 3,6 x 10(6) CFU/ml. Porphyromonas gingivalis was identified in the samples taken from 17 patients, Prevotella intermedia-19, Actinobacillus actinomycetemcomitans -11, Fusobacterium nucleatum-9, Peptostreptococcus spp.-22. 相似文献
8.
The effect of a novel flavonoid, venoruton (a mixture of mono-, di-, tri- and tetrahydroxyethylrutosides) has been investigated in healthy rat lenses and compared with diabetic cataract modelled in vitro. One mM venoruton was added to medium simulating healthy and diabetic conditions for the incubated lenses; damage was followed by either stereoscopic photography of the lenses under a Cooperative Cataract Research Group operating microscope or with our recently developed method: the leakage of lactate dehydrogenase (LDH) into the lens culture media. The increased LDH activity in the medium and observable development of the opacity were correlated with cell damage, which has been found to be associated with globular degeneration and cataract formation. The extent of opacification and LDH release is reduced if 1 mM venoruton is included in the medium. The protective effect may be related to antioxidant activity against reactive oxygen species: decreased luminol luminescence was shown after venoruton addition to either superoxide-generating hypoxanthine plus xanthine oxidase, or hydrogen peroxide. 相似文献
9.
10.
BBN (BaBi2Nb2O9) is very interesting and promising lead free material with relaxor properties in capacitors, sensors and actuators. 相似文献