全文获取类型
收费全文 | 1745篇 |
免费 | 116篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 12篇 |
化学工业 | 420篇 |
金属工艺 | 36篇 |
机械仪表 | 30篇 |
建筑科学 | 66篇 |
矿业工程 | 2篇 |
能源动力 | 53篇 |
轻工业 | 148篇 |
水利工程 | 7篇 |
石油天然气 | 3篇 |
无线电 | 206篇 |
一般工业技术 | 360篇 |
冶金工业 | 94篇 |
原子能技术 | 23篇 |
自动化技术 | 402篇 |
出版年
2023年 | 21篇 |
2022年 | 34篇 |
2021年 | 37篇 |
2020年 | 50篇 |
2019年 | 51篇 |
2018年 | 55篇 |
2017年 | 65篇 |
2016年 | 66篇 |
2015年 | 53篇 |
2014年 | 63篇 |
2013年 | 125篇 |
2012年 | 109篇 |
2011年 | 151篇 |
2010年 | 99篇 |
2009年 | 98篇 |
2008年 | 111篇 |
2007年 | 88篇 |
2006年 | 88篇 |
2005年 | 72篇 |
2004年 | 59篇 |
2003年 | 47篇 |
2002年 | 39篇 |
2001年 | 16篇 |
2000年 | 16篇 |
1999年 | 25篇 |
1998年 | 24篇 |
1997年 | 35篇 |
1996年 | 23篇 |
1995年 | 16篇 |
1994年 | 18篇 |
1993年 | 20篇 |
1992年 | 11篇 |
1991年 | 9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 | 4篇 |
1975年 | 3篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1971年 | 1篇 |
1967年 | 1篇 |
1954年 | 1篇 |
排序方式: 共有1862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.
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
5.
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
6.
P Leterme A Théwis E Fran?ois P Van Leeuwen B Wathelet J Huisman 《Canadian Metallurgical Quarterly》1996,126(9):2188-2198
We assessed the use of 15N-labeled dietary proteins as a possible tool for the determination of the true ileal amino acid (AA) digestibility in pigs. The first experiment was designed to study the dietary N excretion pattern at the ileum subsequent to the ingestion of a single 15N-labeled meal. In a second experiment, we compared ileal endogenous AA outputs and true AA digestibility estimates obtained in pigs ingesting 15N-labeled dietary proteins in a single meal vs. intravenous infusion of [15N]leucine for 10 d during the ingestion of a pea-based diet and a protein-free starch diet. The proportion of endogenous N found in the ileal digesta differed when the label was delivered orally (50%) vs. intravenously (72%) and changed with time. As a consequence, the true ileal AA digestibilities measured with labeled diets were lower. A third experiment demonstrated that this was due to the rapid recycling of labeled dietary N in endogenous moieties, because 15N was found in blood within 10 min of consuming the labeled meal, within 50 min of consumption in pancreatic enzymes, 90 min in bile and 4 h in ileal mucins. We conclude that the use of 15N-labeled meals for determination of true ileal AA digestibilities is limited by the fast recycling of dietary N in endogenous secretions following a single 15N-labeled meal. The accuracy of results will depend on meaningful estimates of AA flow during a limited period and accurate estimates of 15N in AA. 相似文献
7.
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
8.
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
9.
10.