全文获取类型
收费全文 | 3693篇 |
免费 | 79篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 38篇 |
综合类 | 4篇 |
化学工业 | 758篇 |
金属工艺 | 90篇 |
机械仪表 | 79篇 |
建筑科学 | 146篇 |
矿业工程 | 11篇 |
能源动力 | 88篇 |
轻工业 | 290篇 |
水利工程 | 26篇 |
石油天然气 | 12篇 |
武器工业 | 2篇 |
无线电 | 340篇 |
一般工业技术 | 595篇 |
冶金工业 | 673篇 |
原子能技术 | 41篇 |
自动化技术 | 582篇 |
出版年
2021年 | 34篇 |
2020年 | 32篇 |
2019年 | 38篇 |
2018年 | 65篇 |
2017年 | 47篇 |
2016年 | 53篇 |
2015年 | 45篇 |
2014年 | 94篇 |
2013年 | 216篇 |
2012年 | 132篇 |
2011年 | 188篇 |
2010年 | 121篇 |
2009年 | 129篇 |
2008年 | 176篇 |
2007年 | 136篇 |
2006年 | 140篇 |
2005年 | 128篇 |
2004年 | 102篇 |
2003年 | 96篇 |
2002年 | 101篇 |
2001年 | 61篇 |
2000年 | 57篇 |
1999年 | 61篇 |
1998年 | 145篇 |
1997年 | 87篇 |
1996年 | 72篇 |
1995年 | 66篇 |
1994年 | 50篇 |
1993年 | 62篇 |
1992年 | 39篇 |
1991年 | 51篇 |
1990年 | 45篇 |
1989年 | 36篇 |
1988年 | 39篇 |
1987年 | 41篇 |
1986年 | 62篇 |
1985年 | 52篇 |
1984年 | 46篇 |
1983年 | 44篇 |
1982年 | 41篇 |
1981年 | 52篇 |
1980年 | 43篇 |
1979年 | 42篇 |
1978年 | 39篇 |
1977年 | 43篇 |
1976年 | 39篇 |
1975年 | 34篇 |
1973年 | 24篇 |
1972年 | 24篇 |
1971年 | 24篇 |
排序方式: 共有3775条查询结果,搜索用时 15 毫秒
1.
Effect of Bimodal Grain Size Distribution on the Strain Hardening Behavior of a Medium-Entropy Alloy
The evolution of strain hardening behavior of the Fe_(50)(CoCrMnNi)_(50) medium-entropy alloy as a function of the fraction of recrystallized microstructure and the grain size was studied using the Hollomon and Ludwigson equations.The specimens under study were partially recrystallized,fully recrystallized with ultrafine-grained microstructure,and fully recrystallized with coarse grains.The yield strength decreases steadily as the fraction of recry stallized micro structure and grain size increases due to the recovery process and the Hall-Petch effect.Interestingly,the bimodal grain distribution was found to have a significant impact on strain hardening during plastic deformation.For instance,the highest ultimate tensile strength was exhibited by a 0.97 μm specimen,which was observed to contain a bimodal grain distribution.Furthermore,using the Ludwigson equation,the effect of the bimodal grain distribution was established from the behavior of K_2 and n1 curves.These curves tend to show very high values in the specimens with a bimodal grain distribution compared to those that show a homogenous grain distribution.Additionally,the bimodal grain distribution contributes to the extensive L(u|")ders strain observed in the 0.97 μm specimen,which induces a significant deviation of the Hollomon equation at lower strains. 相似文献
2.
Pascal Habimana Yanjun Jiang Jing Gao Jean Bernard Ndayambaje Osama M. Darwesh Jean Pierre Mwizerwa Xiaobing Zheng Li Ma 《中国化学工程学报》2022,48(8):66-75
The continuous use of chemical dyes in various industries, and their discharge into industrial effluents, results in severe problems to human life and water pollution. Laccases have the ability to decolorize dyes and toxic chemicals in industrial effluents as green biocatalysts. Their possible industrial applications have been limited by poor reusability, low stability, and loss of free laccase action. In this research, laccase was immobilized on zeolitic imidazolate framework coated multi-walled carbon nanotubes (Laccase@ZIF-8@MWCNTs) via metal affinity adsorption to develop an easy separable and stable enzyme. The optimum reaction conditions for immobilized laccase are at a pH of 3.0 and a temperature of 60?℃. The immobilized laccase was enhanced in storage and thermal stability. The results indicated that Laccase@ZIF-8@MWCNTs still maintained 68% of its original activity after 10 times of repeated use. Most importantly, the biocatalytic system was applied for decolorization of different dyes (20?mg·L?1) without a mediator, and up to 97.4% for Eriochrome black T and 95.6% Acid red 88 was achieved in 25 min. Biocatalysts with these properties may be used in a variety of environmental and industrial applications. 相似文献
3.
Siyao Li Shoulei Xu Xiangyu Wang Daini Wang Bernard A. Goodman Xing Hong Wen Deng 《Ceramics International》2021,47(3):3346-3353
Cubic zirconia single crystals stabilized with yttria and doped with Gd2O3 (0.10–5.00 mol%) were prepared by the optical floating zone method, and characterized by a combination of X-ray diffraction (XRD), and Raman, electron paramagnetic resonance (EPR), ultraviolet–visible (UV–Vis), photoluminescence excitation (PLE) and photoluminescence (PL) spectroscopic techniques. XRD and Raman spectroscopy showed that the crystal samples were all in the cubic phase, whereas the ceramic sample consisted of a mixture of monoclinic and cubic phases. The absorption spectrum showed four peaks at 245, 273, 308, and 314 nm in the ultraviolet region, and the optical band gap differed between samples with ≤3.00 mol% and those with >3.00 mol% Gd2O3. The emission spectrum showed a weak peak at 308 nm and a strong peak at 314 nm, which are attributed to the 6P5/2 → 8S7/2 and 6P7/2 → 8S7/2 transitions of Gd3+, respectively. The intensities of the peaks in the excitation and emission spectra increased with Gd3+ concentration, reached a maximum at 2.00 mol%, then decreased with higher concentrations. This quenching is considered to be the result of the electric dipole-dipole interactions, and this interpretation is supported by the Gd3+ EPR spectra, which showed progressive broadening with increasing Gd3+ concentration throughout the concentration range investigated. 相似文献
4.
5.
Localized Neuron Stimulation with Organic Electrochemical Transistors on Delaminating Depth Probes 下载免费PDF全文
6.
Ingrid D. Santaren Richard P. Bazinet Zhen Liu Luke W. Johnston John L. Sievenpiper Adria Giacca Ravi Retnakaran Stewart B. Harris Bernard Zinman Anthony J. Hanley 《Lipids》2019,54(10):617-627
Circulating fatty acids (FA) derived largely from dairy consumption have most commonly been measured in total human serum or phospholipid (PL) fractions, and have been used as validated biomarkers of dairy intake in a growing number of epidemiological studies. Nevertheless, measurement and characterization of a wider spectrum of FA biomarkers of dairy across the four major serum lipid fractions is lacking. This study aimed to (1) quantify FA biomarkers of dairy in PL, triacylglycerol (TAG), cholesteryl ester (CE), and unesterified fatty acid (FFA) serum lipid fractions; and (2) identify potential demographic and metabolic factors that may modify the proportions of these FA across serum fractions. Baseline data from 444 adults in the PROMISE cohort were analyzed. FA biomarkers, 15:0, t16:1n-7, 18:2-c9,t11, and t18:1n-7 were quantified from serum. Dairy intake was estimated using the validated Canadian Diet History Questionnaire. Our results show that t18:1n-7 was the most abundant FA biomarker in all fractions except CE, where 18:2-c9,t11 was the most abundant. Positive correlations within fractions, and across FA in the PL, CE, and FFA fractions were found, however, TAG FA were negatively correlated with the other fractions. PL and CE FA were positively associated with dairy intake, and negatively associated with markers of dysmetabolism while, in contrast, these markers were predictors of higher TAG dairy FA. This study is the first to demonstrate distinct proportions of dairy FA in different serum lipid fractions. PL and CE FA marked dairy intake in this cohort, while TAG FA appeared to be markers of dysmetabolism. 相似文献
7.
Din Salah Ud Shao Junming Kumar Jay Mawuli Cobbinah Bernard Mahmud S. M. Hasan Zhang Wei Yang Qinli 《Knowledge and Information Systems》2021,63(9):2231-2276
Knowledge and Information Systems - Developing effective and efficient data stream classifiers is challenging for the machine learning community because of the dynamic nature of data streams. As a... 相似文献
8.
9.
10.
Novel Tacrine‐Grafted Ugi Adducts as Multipotent Anti‐Alzheimer Drugs: A Synthetic Renewal in Tacrine–Ferulic Acid Hybrids 下载免费PDF全文
Mohamed Benchekroun Dr. Manuela Bartolini Dr. Javier Egea Dr. Alejandro Romero Dr. Elena Soriano Dr. Marc Pudlo Vincent Luzet Prof. Vincenza Andrisano Dr. María‐Luisa Jimeno Dr. Manuela G. López Sarah Wehle Prof. Tijani Gharbi Prof. Bernard Refouvelet Lucía de Andrés Clara Herrera‐Arozamena Prof. Barbara Monti Prof. Maria Laura Bolognesi Prof. María Isabel Rodríguez‐Franco Prof. Dr. Michael Decker Prof. José Marco‐Contelles Dr. Lhassane Ismaili 《ChemMedChem》2015,10(3):523-539
Herein we describe the design, multicomponent synthesis, and biological, molecular modeling and ADMET studies, as well as in vitro PAMPA‐blood–brain barrier (BBB) analysis of new tacrine–ferulic acid hybrids (TFAHs). We identified (E)‐3‐(hydroxy‐3‐methoxyphenyl)‐N‐{8[(7‐methoxy‐1,2,3,4‐tetrahydroacridin‐9‐yl)amino]octyl}‐N‐[2‐(naphthalen‐2‐ylamino)2‐oxoethyl]acrylamide (TFAH 10 n ) as a particularly interesting multipotent compound that shows moderate and completely selective inhibition of human butyrylcholinesterase (IC50=68.2 nM ), strong antioxidant activity (4.29 equiv trolox in an oxygen radical absorbance capacity (ORAC) assay), and good β‐amyloid (Aβ) anti‐aggregation properties (65.6 % at 1:1 ratio); moreover, it is able to permeate central nervous system (CNS) tissues, as determined by PAMPA‐BBB assay. Notably, even when tested at very high concentrations, TFAH 10 n easily surpasses the other TFAHs in hepatotoxicity profiling (59.4 % cell viability at 1000 μM ), affording good neuroprotection against toxic insults such as Aβ1–40, Aβ1–42, H2O2, and oligomycin A/rotenone on SH‐SY5Y cells, at 1 μM . The results reported herein support the development of new multipotent TFAH derivatives as potential drugs for the treatment of Alzheimer′s disease. 相似文献