全文获取类型
收费全文 | 47301篇 |
免费 | 2998篇 |
国内免费 | 76篇 |
专业分类
电工技术 | 356篇 |
综合类 | 131篇 |
化学工业 | 11449篇 |
金属工艺 | 933篇 |
机械仪表 | 929篇 |
建筑科学 | 1502篇 |
矿业工程 | 101篇 |
能源动力 | 1354篇 |
轻工业 | 8961篇 |
水利工程 | 461篇 |
石油天然气 | 275篇 |
武器工业 | 2篇 |
无线电 | 2068篇 |
一般工业技术 | 7316篇 |
冶金工业 | 7564篇 |
原子能技术 | 236篇 |
自动化技术 | 6737篇 |
出版年
2024年 | 102篇 |
2023年 | 442篇 |
2022年 | 1191篇 |
2021年 | 1683篇 |
2020年 | 1128篇 |
2019年 | 1242篇 |
2018年 | 1883篇 |
2017年 | 1826篇 |
2016年 | 1932篇 |
2015年 | 1377篇 |
2014年 | 1895篇 |
2013年 | 3620篇 |
2012年 | 3019篇 |
2011年 | 3119篇 |
2010年 | 2409篇 |
2009年 | 2260篇 |
2008年 | 2071篇 |
2007年 | 1842篇 |
2006年 | 1417篇 |
2005年 | 1188篇 |
2004年 | 1024篇 |
2003年 | 1006篇 |
2002年 | 835篇 |
2001年 | 658篇 |
2000年 | 581篇 |
1999年 | 615篇 |
1998年 | 2718篇 |
1997年 | 1755篇 |
1996年 | 1161篇 |
1995年 | 669篇 |
1994年 | 544篇 |
1993年 | 507篇 |
1992年 | 194篇 |
1991年 | 175篇 |
1990年 | 138篇 |
1989年 | 138篇 |
1988年 | 159篇 |
1987年 | 147篇 |
1986年 | 123篇 |
1985年 | 140篇 |
1984年 | 119篇 |
1983年 | 89篇 |
1982年 | 90篇 |
1981年 | 125篇 |
1980年 | 119篇 |
1979年 | 54篇 |
1978年 | 61篇 |
1977年 | 166篇 |
1976年 | 295篇 |
1973年 | 66篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
D. Solís-Cortés E. Navarrete-Astorga J.L. Costa-Krämer J. Salguero-Fernandez R. Schrebler D. Leinen E.A. Dalchiele J.R. Ramos-Barrado F. Martín 《Ceramics International》2019,45(5):5577-5587
C-axis textured thin films of gallium-doped indium zinc oxide (GIZO) with a 2% ratio of Ga/Zn, were obtained via RF-magnetron sputtering with high transparency and electrical conductivity. A Box-Behnken response surface design was used to evaluate the effects of the deposition parameters (In2O3 target power, deposition time, and substrate temperature) on the chemical composition, optical, electrical, and structural properties of the GIZO films. The optical constants and the electrical properties were obtained using optical models. The GIZO stoichiometry, and therefore the In/Zn atomic ratio, affected the crystallinity, crystalline parameters, band gap, and charge carrier mobility of the GIZO films. The charge carrier density was related to the change in the crystalline parameters of the hexagonal structure and the In/Zn atomic ratio. The best electrical conductivity values (1.75?×?103 Ω?1 cm?1) were obtained for GIZO films with In/Zn ratio ≥?1. Several figures of merit (FOM) defined for the visible and solar regions were comparatively used to select the optimal In/Zn atomic ratio that provided the best balance between the conductivity and the transparency. The optimal In/Zn ratio was in a range of 0.85–0.90 for the GIZO films. 相似文献
62.
Real‐time monitoring by proton relaxometry of radical polymerization reactions of acrylamide in aqueous solution
下载免费PDF全文
![点击此处可从《Polymer International》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Elton Jorge da Rocha Rodrigues Roberto Pinto Cucinelli Neto Pedro José Oliveira Sebastião Maria Inês Bruno Tavares 《Polymer International》2018,67(6):675-683
The potential of time‐domain nuclear magnetic resonance (TD‐NMR) for the real‐time monitoring of solution radical polymerizations is demonstrated. A model system composed of a redox‐pair initiator system, acrylamide as monomer and water as solvent was investigated. A second‐generation continuous wave free precession technique was employed to measure the longitudinal relaxation time constant (T1) of the samples throughout the polymerization reactions. This parameter was shown to be sensitive to the reactant feed free‐radical enhancement of the water molecule relaxation time, making it a good probe to monitor monomer conversion in real time in an automated, non‐destructive fashion. It was found that the T1 value was better than the transverse relaxation time constant (T2) for describing the evolution of the polymerization reactions, due to its greater sensitivity to paramagnetic effects. The TD‐NMR signal variation observed was linked to the formation, propagation and termination steps of the radical polymerization kinetics scheme. These first results may contribute to the application of real‐time monitoring of radical polymerization reactions employing low‐cost and robust TD‐NMR spectrometers. © 2018 Society of Chemical Industry 相似文献
63.
64.
Mri Miczi Mria Golda Balzs Kunkli Tibor Nagy Jzsef Tzsr Jnos Andrs Mtyn 《International journal of molecular sciences》2020,21(24)
The novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative agent of coronavirus disease-19 (COVID-19) being associated with severe pneumonia. Like with other viruses, the interaction of SARS-CoV-2 with host cell proteins is necessary for successful replication, and cleavage of cellular targets by the viral protease also may contribute to the pathogenesis, but knowledge about the human proteins that are processed by the main protease (3CLpro) of SARS-CoV-2 is still limited. We tested the prediction potentials of two different in silico methods for the identification of SARS-CoV-2 3CLpro cleavage sites in human proteins. Short stretches of homologous host-pathogen protein sequences (SSHHPS) that are present in SARS-CoV-2 polyprotein and human proteins were identified using BLAST analysis, and the NetCorona 1.0 webserver was used to successfully predict cleavage sites, although this method was primarily developed for SARS-CoV. Human C-terminal-binding protein 1 (CTBP1) was found to be cleaved in vitro by SARS-CoV-2 3CLpro, the existence of the cleavage site was proved experimentally by using a His6-MBP-mEYFP recombinant substrate containing the predicted target sequence. Our results highlight both potentials and limitations of the tested algorithms. The identification of candidate host substrates of 3CLpro may help better develop an understanding of the molecular mechanisms behind the replication and pathogenesis of SARS-CoV-2. 相似文献
65.
László Lőrincz Máté Zsemberi György Bánsághi Tamás Sohajda Edit Székely 《化学工程与技术》2018,41(7):1466-1472
Chiral molecules, especially enantiomers and diastereomers of purity > 99 %, present a significant market share within the chemical, pharmaceutical, and flavor industries. Antisolvent precipitations, both batch and semicontinuous operations to serve the current trends in flow chemistry were demonstrated to be environmentally benign and efficient tools in achieving high optical purities. Although salts are known to be insoluble in supercritical CO2, instabilities of the nascent salts were detected and applied for increasing efficiency. Diastereomeric excess values of the crystalline products exceeded 99 % in maximum of three consecutive steps both by repeated resolution with half molar equivalent of the amine to the acid and by direct recrystallization of the salts. 相似文献
66.
67.
68.
69.
70.
Dr. Li Di Prof. Per Artursson Dr. Alex Avdeef Prof. Leslie Z. Benet Prof. J. Brian Houston Dr. Manfred Kansy Edward H. Kerns Prof. Hans Lennernäs Dr. Dennis A. Smith Prof. Kiyohiko Sugano 《ChemMedChem》2020,15(20):1862-1874
Passive permeability is a key property in drug disposition and delivery. It is critical for gastrointestinal absorption, brain penetration, renal reabsorption, defining clearance mechanisms and drug-drug interactions. Passive diffusion rate is translatable across tissues and animal species, while the extent of absorption is dependent on drug properties, as well as in vivo physiology/pathophysiology. Design principles have been developed to guide medicinal chemistry to enhance absorption, which combine the balance of aqueous solubility, permeability and the sometimes unfavorable compound characteristic demanded by the target. Permeability assays have been implemented that enable rapid development of structure-permeability relationships for absorption improvement. Future advances in assay development to reduce nonspecific binding and improve mass balance will enable more accurately measurement of passive permeability. Design principles that integrate potency, selectivity, passive permeability and other ADMET properties facilitate rapid advancement of successful drug candidates to patients. 相似文献