全文获取类型
收费全文 | 50205篇 |
免费 | 2440篇 |
国内免费 | 58篇 |
专业分类
电工技术 | 291篇 |
综合类 | 33篇 |
化学工业 | 10041篇 |
金属工艺 | 774篇 |
机械仪表 | 863篇 |
建筑科学 | 1402篇 |
矿业工程 | 85篇 |
能源动力 | 1266篇 |
轻工业 | 8323篇 |
水利工程 | 438篇 |
石油天然气 | 208篇 |
武器工业 | 3篇 |
无线电 | 1824篇 |
一般工业技术 | 6612篇 |
冶金工业 | 14383篇 |
原子能技术 | 230篇 |
自动化技术 | 5927篇 |
出版年
2024年 | 85篇 |
2023年 | 390篇 |
2022年 | 826篇 |
2021年 | 1297篇 |
2020年 | 955篇 |
2019年 | 1063篇 |
2018年 | 1565篇 |
2017年 | 1560篇 |
2016年 | 1685篇 |
2015年 | 1327篇 |
2014年 | 1650篇 |
2013年 | 3294篇 |
2012年 | 2592篇 |
2011年 | 2805篇 |
2010年 | 2160篇 |
2009年 | 2037篇 |
2008年 | 1934篇 |
2007年 | 1715篇 |
2006年 | 1292篇 |
2005年 | 1129篇 |
2004年 | 1050篇 |
2003年 | 958篇 |
2002年 | 847篇 |
2001年 | 612篇 |
2000年 | 572篇 |
1999年 | 833篇 |
1998年 | 4963篇 |
1997年 | 2998篇 |
1996年 | 1971篇 |
1995年 | 1065篇 |
1994年 | 870篇 |
1993年 | 951篇 |
1992年 | 220篇 |
1991年 | 223篇 |
1990年 | 183篇 |
1989年 | 201篇 |
1988年 | 211篇 |
1987年 | 203篇 |
1986年 | 168篇 |
1985年 | 190篇 |
1984年 | 115篇 |
1983年 | 97篇 |
1982年 | 109篇 |
1981年 | 137篇 |
1980年 | 169篇 |
1978年 | 66篇 |
1977年 | 322篇 |
1976年 | 642篇 |
1975年 | 68篇 |
1973年 | 62篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
Lorena Rodríguez-López Myriam Rincón-Fontán Xanel Vecino Ana B. Moldes Jose M. Cruz 《Journal of surfactants and detergents》2020,23(1):79-90
Over the last few years, the global biosurfactant market has raised due to the increasing awareness among consumers, for the use of biological or bio-based products. Because of their composition, it can be speculated that these are more biocompatible and more biodegradable than their chemical homologous. However, at the moment, no studies exist in the literature about the biodegradability of biosurfactants. In this work, a biosurfactant contained in a crude extract, obtained from a corn wet-milling industry stream that ferments spontaneously in the presence of lactic acid bacteria, was subjected to a biodegradation study, without addition of external microbial biomass, under different conditions of temperature (5–45 °C), biodegradation time (15–55 days), and pH (5–7). For that, a Box–Behnken factorial design was applied, which allowed to predict the percentage of biodegradation for the biosurfactant contained in the crude extract, between the range of the independent variables selected in the study, obtaining biodegradation values between 3 and 80%. The percentage of biodegradation for the biosurfactant was calculated based on the increase in the surface tension of samples of the crude extract. Furthermore, it was also possible to predict the variation in t1/2 for the biosurfactant (time to achieve the 50% of biodegradation) under different conditions. 相似文献
42.
43.
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
44.
45.
María Clara Verdi Constanza Melian Patricia Castellano Graciela Vignolo Mariana Blanco Massani 《International Journal of Food Science & Technology》2020,55(1):267-275
The effectiveness of antimicrobial mixtures against Listeria innocua 7, used as a L. monocytogenes surrogate, was investigated in broth and a food system. Synergistic effects were found for nisin (Nis), potassium sorbate (PS), calcium propionate (CP) and sodium lactate (SL), Nis + PS being the most effective binary mixture that exhibited listericidal activity in broth. To assess the effect of adding lactocin AL705 (AL705) to Nis + organic acid salt combinations, tridimensional isobolograms were generated. Sub-MIC combinations of the antimicrobials exerted bactericidal activity against L. innocua 7 after AL705 addition to the binary mixtures. However, when applied on Sardo cheese contaminated with L. innocua 7 (initial inoculum 4.45 ± 0.06 CFU g−1), only Nis + PS + AL705 produced count reductions respect to the control, reaching 3.04 ± 0.35 CFU g−1 counts after 15 days at 15 °C. Ternary combinations containing AL705 showed potential to reduce antimicrobial usages for L. innocua 7 inhibition. 相似文献
46.
47.
48.
Tsuchiya Letícia Diniz Braga Lucas Fiorini de Faria Oliveira Otávio de Bettio Raphael Winckler Greghi Juliana Galvani Freire André Pimenta 《Personal and Ubiquitous Computing》2021,25(2):281-295
Personal and Ubiquitous Computing - This article presents a study concerning the evaluation of a smart home control system for elderly people with a sample of 10 users in a city in the interior of... 相似文献
49.
50.
Caio Felippe Curitiba Marcellos Camila M. Senna Figueiredo Frederico W. Tavares Maurício Bezerra de Souza Jr. Paulo Laranjeira da Cunha Lage João Francisco Cajaiba da Silva Argimiro R. Secchi Amaro G. Barreto Jr. 《加拿大化工杂志》2020,98(11):2435-2450
An experimental methodology for inferring brine dissolution rate in monoethylene glycol (MEG) solutions at different temperatures using a webcam combined with a mathematical model is presented. The measurement system is designed to track the RGB (red, green, and blue) colour variations during the dissolution process. A dynamic model augmented with the population balance equation is applied to describe the dissolution process. Moreover, the dissolution rate is consistently related to the temperature and MEG concentration through the driving force based on the Gibbs energy and chemical affinity. The applied low-cost measurement apparatus proved to be a useful resource for tracking the dissolution dynamics in a wide range of undersaturation. 相似文献