全文获取类型
收费全文 | 2863篇 |
免费 | 55篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 60篇 |
综合类 | 4篇 |
化学工业 | 424篇 |
金属工艺 | 53篇 |
机械仪表 | 30篇 |
建筑科学 | 92篇 |
矿业工程 | 18篇 |
能源动力 | 40篇 |
轻工业 | 282篇 |
水利工程 | 12篇 |
石油天然气 | 3篇 |
无线电 | 79篇 |
一般工业技术 | 269篇 |
冶金工业 | 1315篇 |
原子能技术 | 12篇 |
自动化技术 | 228篇 |
出版年
2022年 | 26篇 |
2021年 | 35篇 |
2020年 | 17篇 |
2019年 | 19篇 |
2018年 | 36篇 |
2017年 | 21篇 |
2016年 | 46篇 |
2015年 | 45篇 |
2014年 | 41篇 |
2013年 | 71篇 |
2012年 | 51篇 |
2011年 | 82篇 |
2010年 | 68篇 |
2009年 | 56篇 |
2008年 | 64篇 |
2007年 | 75篇 |
2006年 | 39篇 |
2005年 | 47篇 |
2004年 | 39篇 |
2003年 | 39篇 |
2002年 | 35篇 |
2001年 | 29篇 |
2000年 | 25篇 |
1999年 | 62篇 |
1998年 | 397篇 |
1997年 | 212篇 |
1996年 | 174篇 |
1995年 | 101篇 |
1994年 | 80篇 |
1993年 | 95篇 |
1992年 | 32篇 |
1991年 | 43篇 |
1990年 | 35篇 |
1989年 | 33篇 |
1988年 | 29篇 |
1987年 | 20篇 |
1986年 | 26篇 |
1985年 | 34篇 |
1984年 | 20篇 |
1983年 | 17篇 |
1982年 | 26篇 |
1981年 | 20篇 |
1980年 | 24篇 |
1979年 | 18篇 |
1978年 | 16篇 |
1977年 | 61篇 |
1976年 | 71篇 |
1975年 | 26篇 |
1974年 | 15篇 |
1973年 | 15篇 |
排序方式: 共有2921条查询结果,搜索用时 15 毫秒
21.
22.
23.
24.
25.
A surgical technique for secondary emplacement of an orbital implant is described in which a spherical implant encased in a scleral homograft is placed in the orbit through a transconjuctival incision and sutured to the superior part of the periosteum. 相似文献
26.
Labuda R Parich A Berthiller F Tancinová D 《International journal of food microbiology》2005,105(1):19-25
A total of 50 samples of poultry feed mixtures of Slovakian origin were analyzed for eight toxicologically significant Fusarium mycotoxins, namely zearalenone (ZON), A-trichothecenes: diacetoxyscirpenol (DAS), T-2 toxin (T-2) and HT-2 toxin (HT-2) and B-trichothecenes: deoxynivalenol (DON), 3-acetyl-deoxynivalenol (3-ADON), 15-acetyl-deoxynivalenol (15-ADON) and nivalenol (NIV). The A-trichothecenes and the B-trichothecenes were detected by means of high pressure liquid chromatography with tandem mass spectrometry detection (HPLC-MS/MS) and gas chromatography electron capture detection (GC-ECD), respectively. Reversed phase-high performance liquid chromatography with a fluorescence detector (RP-HPLC-FLD) was used for ZON detection. The most frequent mycotoxin detected was T-2, which was found in 45 samples (90%) in relatively low concentrations ranging from 1 to 130 microg kg(-1) (average 13 microg kg(-1)), followed by ZON that was found in 44 samples (88%) in concentrations ranging from 3 to 86 microg kg(-1) (average 21 microg kg(-1)). HT-2 and DON were detected in 38 (76%) and 28 (56%) samples, respectively, in concentrations of 2 to 173 (average 18 microg kg(-1)) for HT-2 and 64 to 1230 microg kg(-1) sample (average 303 microg kg(-1)) for DON. The acetyl-derivatives of DON were in just four samples, while NIV was not detected in any of the samples investigated. In as many as 22 samples (44%), a combination of four simultaneously co-occurring mycotoxins, i.e. T-2, HT-2, ZON and DON, was revealed. Despite the limited number of samples investigated during this study poultry feed mixtures may represent a risk from a toxicological point of view and should be regarded as a potential source of the Fusarium mycotoxins in Central Europe. This is the first reported study dealing with zearalenone and trichothecene contamination of poultry mixed feeds from Slovakia. 相似文献
27.
Abiodun Sanni Charles Franz Ulrich Schillinger Melanie Huch Claudia Guigas Wilhelm Holzapfel 《Food Biotechnology》2013,27(2):178-198
A total of 57 predominant LAB strains isolated from cassava and maize grains fermentation processes for fufu and ogi were identified using phenotypic and genomic fingerprinting methods such as rep-PCR and ARDRA. They were divided into facultatively heterofermentative rods (26.3%), obligately heterofermentative rods (31.6%), and tetrad forming homofermentative cocci (42.1%). Selected strains were further identified by sequencing the 16S rDNA gene. Technological studies such as acidification, hydrogen peroxide production, starch hydrolysis, enzymatic activities, degradation of oligosaccharides, and in vitro adherence properties were carried out. Lactobacillus plantarum strains demonstrated better and rapid acid production capability, followed by the Pediococcus strains, while L. fermentum strains exhibited slower acid production. Hydrogen peroxide production was observed among the LAB groups. The test strains utilized the indigestible sugars raffinose and stachyose. Only L. pentosus demonstrated high amylase activity comparable to that of L. amylovorus DSM 20531. Lactobacillus plantarum and L. fermentum strains showed high β-glucosidase activity. Six strains were selected as starter cultures. The strains were tolerant to acidic pH levels and bile salt. The yoghurt-like “sorghurt” produced using the selected starter cultures had a final pH of less than pH 4.0, and a viable count of less than 5.5 Log10cfu/mL at the end of a 24 h fermentation period. The samples were generally acceptable to the taste panelists. The starter organisms demonstrated varying degree of adherence to HT29 MTX cell line. Therefore, employing functionally defined LAB strains may be one practical approach for incorporating health-promoting features into appropriate food products suitable for targeted population. 相似文献
28.
Franz Berthiller Colin Crews Chiara Dall'Asta Sarah De Saeger Geert Haesaert Petr Karlovsky Isabelle P. Oswald Walburga Seefelder Gerrit Speijers Joerg Stroka 《Molecular nutrition & food research》2013,57(1):165-186
The aim of this review is to give a comprehensive overview of the current knowledge on plant metabolites of mycotoxins, also called masked mycotoxins. Mycotoxins are secondary fungal metabolites, toxic to human and animals. Toxigenic fungi often grow on edible plants, thus contaminating food and feed. Plants, as living organisms, can alter the chemical structure of mycotoxins as part of their defence against xenobiotics. The extractable conjugated or non‐extractable bound mycotoxins formed remain present in the plant tissue but are currently neither routinely screened for in food nor regulated by legislation, thus they may be considered masked. Fusarium mycotoxins (deoxynivalenol, zearalenone, fumonisins, nivalenol, fusarenon‐X, T‐2 toxin, HT‐2 toxin, fusaric acid) are prone to metabolisation or binding by plants, but transformation of other mycotoxins by plants (ochratoxin A, patulin, destruxins) has also been described. Toxicological data are scarce, but several studies highlight the potential threat to consumer safety from these substances. In particular, the possible hydrolysis of masked mycotoxins back to their toxic parents during mammalian digestion raises concerns. Dedicated chapters of this article address plant metabolism as well as the occurrence of masked mycotoxins in food, analytical aspects for their determination, toxicology and their impact on stakeholders. 相似文献
29.
Antimicrobial packaging based on ɛ‐polylysine bioactive film for the control of mycotoxigenic fungi in vitro and in bread 下载免费PDF全文
C. Luz J. Calpe F. Saladino Fernando B. Luciano M. Fernandez‐Franzón J. Mañes G. Meca 《Journal of Food Processing and Preservation》2018,42(1)
?‐Poly‐l‐ lysine (?‐PL) is a cationic peptide with a broad‐spectrum antimicrobial activity. This study investigates the use of ?‐PL as natural antimicrobial to inhibit fungal growth and to reduce aflatoxins (AFs) production. Antifungal activity of starch biofilms with different concentrations of ?‐Poly‐l‐ lysine (?‐PL) was determined in solid medium against Aspergillus parasiticus (AFs producer) and Penicillium expansum. Then, biofilms were tested as antimicrobial devices for the preservation of bread loaf inoculated with A. parasiticus CECT 2681 and P. expansum CECT 2278. Shelf life and AFs content were examined. Biofilms with concentrations of ?‐PL less than 1.6 mg/cm2 showed no fungal growth inhibition in solid medium, while the antifungal activity of the films with greater than 1.6 mg/cm2 of ?‐PL was dose dependent. The shelf life of bread inoculated with A. parasiticus was increased by 1 day with the use of films containing 1.6–6.5 mg ?‐PL/cm2, while shelf life of bread tainted with P. expansum was increased by 3 day with 6.5 mg ?‐PL/cm2. AFs production was greatly inhibited by ?‐PL biofilms (93–100%). Thus, ?‐PL biofilms could be potentially used as antimicrobial device during bread storage as a natural alternative to the synthetic preservatives.
Practical applications
?‐Polylysin is a natural substance from microbial metabolism. Polylysine has a function to prevent a microbe from proliferating by ionic adsorption in the microbe. ?‐polylysine has a wide antibacterial spectrum and has an obvious lethal effect on Gram‐positive and Gram‐negative bacteria, yeast, mold, viruses, etc. It has a good antibacterial effect on the Gram‐negative bacteria E. coli and Salmonellae, which are difficult to control with other natural preservatives. ?‐Polylysine has already been used generally as a food additive in Japan, Korea and other part of world. In the United States, FDA has recognized the polylysine as a GRAS material. Considered the positive results obtained in the study, this compound could be used for the production of antimicrobial biofilms, applied as separator slices in the loaf bread production, to prevent the growth of the mycotoxigenic fungi A. parasiticus and P. expansum, contributing to reduce the use of the synthetically preservatives in bakery industry and also of the negative impact that these compounds could generate on the health of the end users. 相似文献30.
Krammer GE Weckerle B Brennecke S Weber B Kindel G Ley J Hilmer JM Reinders G Stöckigt D Hammerschmidt FJ Ott F Gatfield I Schmidt CO Bertram HJ 《Molecular nutrition & food research》2006,50(4-5):345-350
In the past flavor research and the development of new flavorings were constantly driven by the interaction of flavor analysis, structure elucidation, and chemical synthesis accompanied by sensory. Highly potent flavor compounds were identified in numerous food products and helped to establish a powerful toolbox for flavorists. Nowadays we experience the merging of various scientific disciplines, for example medicine, biology, chemistry, and various technologies in the field of flavor research, which shows direct impact on our understanding of flavors. At the same time modern life has profoundly changed our eating habits. This situation generates new challenges for product development teams, which represent all facets of technologies. This paper will illustrate different examples for the evolution of product-oriented flavor research and future trends. 相似文献