全文获取类型
收费全文 | 1749篇 |
免费 | 117篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 12篇 |
化学工业 | 421篇 |
金属工艺 | 36篇 |
机械仪表 | 30篇 |
建筑科学 | 65篇 |
矿业工程 | 2篇 |
能源动力 | 53篇 |
轻工业 | 147篇 |
水利工程 | 7篇 |
石油天然气 | 3篇 |
无线电 | 207篇 |
一般工业技术 | 354篇 |
冶金工业 | 104篇 |
原子能技术 | 23篇 |
自动化技术 | 403篇 |
出版年
2023年 | 21篇 |
2022年 | 31篇 |
2021年 | 37篇 |
2020年 | 50篇 |
2019年 | 51篇 |
2018年 | 56篇 |
2017年 | 65篇 |
2016年 | 66篇 |
2015年 | 53篇 |
2014年 | 63篇 |
2013年 | 126篇 |
2012年 | 109篇 |
2011年 | 151篇 |
2010年 | 99篇 |
2009年 | 98篇 |
2008年 | 112篇 |
2007年 | 87篇 |
2006年 | 87篇 |
2005年 | 72篇 |
2004年 | 58篇 |
2003年 | 47篇 |
2002年 | 39篇 |
2001年 | 15篇 |
2000年 | 16篇 |
1999年 | 25篇 |
1998年 | 27篇 |
1997年 | 38篇 |
1996年 | 24篇 |
1995年 | 17篇 |
1994年 | 18篇 |
1993年 | 20篇 |
1992年 | 11篇 |
1991年 | 8篇 |
1990年 | 9篇 |
1989年 | 5篇 |
1988年 | 7篇 |
1987年 | 4篇 |
1986年 | 4篇 |
1985年 | 4篇 |
1984年 | 6篇 |
1983年 | 5篇 |
1982年 | 5篇 |
1977年 | 5篇 |
1976年 | 5篇 |
1975年 | 3篇 |
1973年 | 1篇 |
1971年 | 1篇 |
1967年 | 1篇 |
1965年 | 1篇 |
1954年 | 1篇 |
排序方式: 共有1867条查询结果,搜索用时 15 毫秒
1.
An antibacterial peptide (AMP), i.e., nisin, was covalently bound to gelatin through a protein–protein coupling. Various reaction conditions were tested to study and optimize parameters of grafting e.g., orientation and density of AMP, which could impact the final antibacterial activity of the modified biopolymer. Modification was investigated by Fourier transform infrared (FT‐IR) spectroscopy and zeta potential. The antibacterial activity of the nisin‐enriched gelatin was evaluated against two staphylococci bacterial strains, i.e., Staphylococus epidermidis and Staphylococcus aureus. A higher activity was found for gelatin modified at pH = 7.4 revealing an influence of the nisin orientation on the protein antibacterial property. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41825. 相似文献
2.
Computer Supported Cooperative Work (CSCW) - 相似文献
3.
4.
RM Campbell EP Heimer M Ahmad HG Eisenbeis TJ Lambros Y Lee RW Miller PR Stricker AM Felix 《Canadian Metallurgical Quarterly》1997,49(6):527-537
In the present study, human growth hormone-releasing factor (hGRF) and analogs were successfully pegylated at the carboxy-terminus using a novel solid- and solution-phase strategy. Following synthesis, these pegylated hGRF analogs were evaluated for in vitro and in vivo biological activity. Specifically, hGRF (1-29)-NH2, [Ala15]-hGRF (1-29)-NH2, [desNH2Tyr1, D-Ala2, Ala15]-hGRF(1-29)-NH2 and [His1, Val2, Gln8, Ala15, Leu27]-hGRF(1-32)-OH were each C-terminally extended using a Gly-Gly-Cys-NH2 spacer (previously demonstrated not to alter intrinsic biological activity), and then monopegylated via coupling to an activated dithiopyridyl-PEG reagent. PEG moieties of 750, 2000, 5000 or 10,000 molecular weight (MW) were examined to determine the effect of polymer weight on activity. Initial biological evaluations in vitro revealed that all C-terminally pegylated hGRF analogs retained high growth hormone (GH)-releasing potencies, regardless of the MW of PEG polymer employed. Two of these pegylated hGRF analogs, [desNH2Tyr1, D-Ala2, Ala15]-hGRF (1-29)-Gly-Gly-Cys(NH2)-S-Nle-PEG5000 and [His1, Val2, Gln8, Ala15, Leu27]-hGRF(1-32)-Gly-Cys(NH2)-S-Nle-PEG5000, were subsequently evaluated in both pig and mouse models and found to be highly potent (in vivo potency range = 12-55-fold that of native hGRF). Relative to their non-pegylated counterparts, these two pegylated hGRF analogs exhibited enhanced duration of activity. 相似文献
5.
Ehrlichia spp. from human and equine sources in the northeastern Unites States were detected by PCR, isolated, and propagated in the HL-60 promyelocytic leukemia cell line. Growth of Ehrlichia from both equine and human sources was enhanced by addition of retinoic acid, which causes granulocytic differentiation of the HL-60 cells. DNA sequencing of a portion of the 16S rDNA gene supported the hypothesis that the same pathogen was responsible for both equine and human granulocytic ehrlichiosis. 相似文献
6.
We study experimentally and theoretically two polarization effects in a vertical cavity surface emitting laser submitted to optical feedback. In a first experiment, we obtain flips between two linearly polarized laser modes up to a frequency of 50 MHz using an external cavity with a polarizer. In a second experiment, polarization self modulation is demonstrated up to a frequency of 2.6 GHz, using a quarter wave plate instead. Numerical calculations, based on a four levels model for the active medium, show a good agreement with the experiments. 相似文献
7.
Summary Considered in this paper is the two-dimensional steady flow of a power-law fluid past a stationary circular cylinder. The governing nonlinear equations, expressed in terms of a stream function and vorticity, were solved by finite differences for Reynolds numbers (based on the radius of the cylinder)R=5,20, 40 for various power-law indices,n. Parameters such as the drag coefficient, separation angle, wake length and critical Reynolds number are presented and contrasted with those of a Newtonian fluid (n=1) to illustrate the non-Newtonian effects. For a given-Reynolds number a consistent behaviour withn was observed in the parameters for the ranges considered. The results obtained for the Newtonian case agree well with documented results. 相似文献
8.
A new method is presented to analyze reflection losses of integrated mirrors, taking into account the exact guided mode profile and assuming that this profile remains unchanged up to the reflecting plane. The fraction of the reflected light coupled to one of the guided modes of the output waveguide is calculated, taking into account the mirror reflection coefficient. The influence of both translation and tilt of the reflecting plane is investigated. The method applies for every guided mode and any reflection angles. Numerical calculations are derived for a 90° optical corner mirror 相似文献
9.
Pascal Bondon 《时间序列分析杂志》2005,26(4):519-525
Abstract. The influence of missing observations on the linear prediction of a stationary time series is investigated. Simple bounds for the prediction error variance and asymptotic behaviours for short and long‐memory processes respectively are presented. 相似文献
10.