全文获取类型
收费全文 | 1310篇 |
免费 | 94篇 |
专业分类
电工技术 | 4篇 |
综合类 | 4篇 |
化学工业 | 332篇 |
金属工艺 | 4篇 |
机械仪表 | 18篇 |
建筑科学 | 57篇 |
矿业工程 | 4篇 |
能源动力 | 17篇 |
轻工业 | 175篇 |
水利工程 | 20篇 |
石油天然气 | 2篇 |
武器工业 | 1篇 |
无线电 | 87篇 |
一般工业技术 | 182篇 |
冶金工业 | 345篇 |
原子能技术 | 1篇 |
自动化技术 | 151篇 |
出版年
2023年 | 15篇 |
2022年 | 56篇 |
2021年 | 73篇 |
2020年 | 28篇 |
2019年 | 35篇 |
2018年 | 37篇 |
2017年 | 31篇 |
2016年 | 56篇 |
2015年 | 42篇 |
2014年 | 55篇 |
2013年 | 67篇 |
2012年 | 66篇 |
2011年 | 111篇 |
2010年 | 92篇 |
2009年 | 74篇 |
2008年 | 70篇 |
2007年 | 84篇 |
2006年 | 48篇 |
2005年 | 52篇 |
2004年 | 50篇 |
2003年 | 27篇 |
2002年 | 26篇 |
2001年 | 20篇 |
2000年 | 18篇 |
1999年 | 13篇 |
1998年 | 12篇 |
1997年 | 18篇 |
1996年 | 12篇 |
1995年 | 13篇 |
1994年 | 13篇 |
1993年 | 9篇 |
1992年 | 5篇 |
1991年 | 2篇 |
1990年 | 7篇 |
1989年 | 7篇 |
1988年 | 9篇 |
1987年 | 8篇 |
1986年 | 6篇 |
1985年 | 5篇 |
1984年 | 4篇 |
1983年 | 6篇 |
1982年 | 2篇 |
1981年 | 3篇 |
1979年 | 3篇 |
1975年 | 4篇 |
1973年 | 2篇 |
1964年 | 1篇 |
1961年 | 1篇 |
1960年 | 1篇 |
1958年 | 1篇 |
排序方式: 共有1404条查询结果,搜索用时 15 毫秒
21.
22.
Venkataraman H Beer SB Bergen LA Essen Nv Geerke DP Vermeulen NP Commandeur JN 《Chembiochem : a European journal of chemical biology》2012,13(4):520-523
Inversion of stereoselectivity: screening of a minimal mutant library revealed a cytochrome P450?BM3 variant M01?A82W?S72I capable of producing 16?α-OH-testosterone. Remarkably, a single active site mutation S72I in M01?A82W inverted the stereoselectivity of hydroxylation from 16?β to 16?α. Introduction of S72I mutation in another 16?β-OH-selective variant M11?V87I, also resulted in similar inversion of stereoselectivity. 相似文献
23.
Stimulus responsive surfactants based on dendritic glycerol azobenzene conjugates were used to solubilize and debundle single-walled carbon nanotubes in aqueous media. Their debundling property as well as their reaggregation behavior upon irradiation with light was examined and light triggered reversible bundling and precipitation are shown. 相似文献
24.
Jake A. Pruett J. Jaime Zúñiga-Vega Stephanie M. Campos Helena A. Soini Milos V. Novotny Cuauhcihuatl Vital-García Emília P. Martins Diana K. Hews 《Journal of chemical ecology》2016,42(11):1164-1174
Animals rely on multimodal signals to obtain information from conspecifics through alternative sensory systems, and the evolutionary loss of a signal in one modality may lead to compensation through increased use of signals in an alternative modality. We investigated associations between chemical signaling and evolutionary loss of abdominal color patches in males of four species (two plain-bellied and two colorful-bellied) of Sceloporus lizards. We conducted field trials to compare behavioral responses of male lizards to swabs with femoral gland (FG) secretions from conspecific males and control swabs (clean paper). We also analyzed the volatile organic compound (VOC) composition of male FG secretions by stir bar extraction and gas chromatography-mass spectrometry (GC-MS) to test the hypothesis that loss of the visual signal is associated with elaboration of the chemical signal. Males of plain-bellied, but not colorful-bellied species exhibited different rates of visual displays when exposed to swabs of conspecific FG secretions relative to control swabs. The VOC composition of male Sceloporus FG secretions was similar across all four species, and no clear association between relative abundances of VOCs and evolutionary loss of abdominal color patches was observed. The emerging pattern is that behavioral responses to conspecific chemical signals are species- and context-specific in male Sceloporus, and compensatory changes in receivers, but not signalers may be involved in mediating increased responsiveness to chemical signals in males of plain-bellied species. 相似文献
25.
Remendable polymers via reversible Diels–Alder cycloaddition of anthracene‐containing copolymers with fullerenes 下载免费PDF全文
Julia Kötteritzsch Robert Geitner Johannes Ahner Marcus Abend Stefan Zechel Jürgen Vitz Stephanie Hoeppener Benjamin Dietzek Michael Schmitt Jürgen Popp Ulrich S. Schubert Martin D. Hager 《应用聚合物科学杂志》2018,135(10)
Poly(lauryl methacrylate)s with anthracene moieties in the side chain were converted with C60‐fullerene and phenyl‐C61‐butyric acid methyl ester (PCBM), resulting in new remendable (self‐healing) polymeric materials. The utilization of differently substituted anthracene monomers enabled the tuning of the reactivity and the resulting mechanical properties. Copolymers with different contents of the anthracene moieties were synthesized and characterized using size exclusion chromatography, 1H nuclear magnetic resonance (NMR) spectroscopy as well as differential scanning calorimetry (DSC). 1H NMR spectroscopic studies were utilized in order to investigate the reversibility of the Diels–Alder reaction between copolymers with C60‐fullerene and PCBM, respectively, in solution. In order to investigate the conversion of the polymers with C60‐fullerene and PCBM in bulk, additionally, DSC, nanoindentation, rheology, atomic force microscopy (AFM), 3D microscopy, simultaneous thermal analysis (STA) and FT‐Raman investigations were performed. The fullerene‐containing copolymers could be healed in a temperature range of 40–80 °C. Consequently, a new generation of low temperature remendable polymers could be established. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45916. 相似文献
26.
Confirmation of the Dominant Defect Mechanism in Amorphous In–Zn–O Through the Application of In Situ Brouwer Analysis 下载免费PDF全文
Stephanie L. Moffitt Alexander U. Adler Thomas Gennett David S. Ginley John D. Perkins Thomas O. Mason 《Journal of the American Ceramic Society》2015,98(7):2099-2103
The dominant point defect mechanism of amorphous (a‐) indium zinc oxide (IZO) was probed through in situ electrical characterization of sputtered a‐IZO thin films in response to changes in oxygen partial pressure (pO) at 300C. The results yielded a power law dependence of conductivity (σ) versus pO of ~?1/6. This experimental method, known as Brouwer analysis, confirms doubly‐charged oxygen vacancies as the dominant defect species in a‐IZO. The success of this study suggests that Brouwer analysis is a viable method for studying the defect mechanisms of amorphous oxides. 相似文献
27.
ABSTRACT The design and synthesis of polymer-supported reagents that can selectively complex targeted metal ions from multi-component solutions will continue to be an important area of research into the 21st century. Environmental remediation and sensor technology are only two of a number of areas in which such polymers can be applied. This paper reviews the recent literature with an emphasis on the key ligands that have been immobilized in order to better understand where this research is heading in the near future. 相似文献
28.
Dr. Rhushikesh A. Kulkarni Dr. Nadeem A. Vellore Matthew R. Bliss Dr. Stephanie M. Stanford Matthew D. Falk Prof. Nunzio Bottini Prof. Riccardo Baron Prof. Amy M. Barrios 《Chembiochem : a European journal of chemical biology》2013,14(13):1640-1647
Assay design is an important variable that influences the outcome of an inhibitor screen. Here, we have investigated the hypothesis that protein tyrosine phosphatase inhibitors with improved biological activity could be identified from a screen by using a biologically relevant peptide substrate, rather than traditional phosphotyrosine mimetic substrates. A 2000‐member library of drugs and drug‐like compounds was screened for inhibitors of lymphoid tyrosine phosphatase (LYP) by using both a peptide substrate (Ac‐ARLIEDNE‐pCAP‐TAREG‐NH2, peptide 1) and a small‐molecule phosphotyrosine mimetic substrate (difluoromethyl umbelliferyl phosphate, DiFMUP). The results demonstrate that compounds that inhibited enzyme activity on the peptide substrate had greater biological activity than compounds that only inhibited enzyme activity on DiFMUP. Finally, epigallocatechin‐3,5‐digallate was identified as the most potent inhibitor of lymphoid tyrosine phosphatase activity to date, with an IC50 of 50 nM and significant activity in T‐cells. Molecular docking simulations provided a first model for binding of this potent inhibitor to LYP; this will constitute the platform for ongoing lead optimization efforts. 相似文献
29.
30.
Dr. Rhushikesh A. Kulkarni Dr. Stephanie M. Stanford Dr. Nadeem A. Vellore Dr. Divya Krishnamurthy Matthew R. Bliss Prof. Riccardo Baron Prof. Nunzio Bottini Prof. Amy M. Barrios 《ChemMedChem》2013,8(9):1561-1568
We screened a small library of thiuram disulfides for inhibition of lymphoid tyrosine phosphatase (LYP) activity. The parent thiuram disulfide, disulfiram, inhibited LYP activity in vitro and in Jurkat T cells, whereas diethyldithiocarbamate failed to inhibit LYP at the concentrations tested. Compound 13 , an N‐(2‐thioxothiazolidin‐4‐one) analogue, was found to be the most potent LYP inhibitor in this series, with an IC50 value of 3 μM . Compound 13 inhibits LYP pseudo‐irreversibly, as evidenced by the time‐dependence of inhibition, with a Ki value of 1.1 μM and a kinact value of 0.004 s?1. The inhibition of LYP by compound 13 could not be reversed significantly by incubation with glutathione or by prolonged dialysis, but could be partially reversed by incubation with dithiothreitol. Compound 13 also inhibited LYP activity in Jurkat T cells. 相似文献