全文获取类型
收费全文 | 2429篇 |
免费 | 162篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 31篇 |
综合类 | 1篇 |
化学工业 | 715篇 |
金属工艺 | 46篇 |
机械仪表 | 86篇 |
建筑科学 | 98篇 |
矿业工程 | 5篇 |
能源动力 | 109篇 |
轻工业 | 320篇 |
水利工程 | 27篇 |
石油天然气 | 18篇 |
无线电 | 135篇 |
一般工业技术 | 373篇 |
冶金工业 | 82篇 |
原子能技术 | 13篇 |
自动化技术 | 535篇 |
出版年
2024年 | 2篇 |
2023年 | 27篇 |
2022年 | 99篇 |
2021年 | 126篇 |
2020年 | 94篇 |
2019年 | 120篇 |
2018年 | 95篇 |
2017年 | 105篇 |
2016年 | 115篇 |
2015年 | 90篇 |
2014年 | 117篇 |
2013年 | 223篇 |
2012年 | 172篇 |
2011年 | 202篇 |
2010年 | 131篇 |
2009年 | 110篇 |
2008年 | 121篇 |
2007年 | 105篇 |
2006年 | 79篇 |
2005年 | 58篇 |
2004年 | 62篇 |
2003年 | 48篇 |
2002年 | 41篇 |
2001年 | 30篇 |
2000年 | 17篇 |
1999年 | 21篇 |
1998年 | 21篇 |
1997年 | 19篇 |
1996年 | 14篇 |
1995年 | 11篇 |
1994年 | 10篇 |
1993年 | 12篇 |
1992年 | 10篇 |
1991年 | 12篇 |
1989年 | 12篇 |
1988年 | 7篇 |
1987年 | 10篇 |
1986年 | 5篇 |
1985年 | 5篇 |
1984年 | 3篇 |
1983年 | 3篇 |
1982年 | 3篇 |
1981年 | 5篇 |
1980年 | 4篇 |
1979年 | 6篇 |
1978年 | 2篇 |
1975年 | 2篇 |
1966年 | 1篇 |
1961年 | 1篇 |
1949年 | 1篇 |
排序方式: 共有2594条查询结果,搜索用时 15 毫秒
991.
Inulin was used as a prebiotic to improve the quality and consistency of skim milk fermented by co-cultures and pure cultures of Lactobacillus acidophilus, Lactobacillus rhamnosus, Lactobacillus bulgaricus and Bifidobacterium lactis with Streptococcus thermophilus. We compared, either in the presence or absence of 4 g inulin/100 g, the results of the main kinetic parameters, specifically the generation time (tg), the maximum acidification rate (Vmax), and the times to reach Vmax (tmax), to attain pH 5.0 (tpH5.0) and to complete the fermentation (tpH4.5). Post-acidification, lactic acid formation and cell counts were also determined and compared, either 1 day after the fermentation was complete or after 7 day storage at 4 °C. In general, inulin addition to the milk increased in co-cultures Vmax, decreased tmax, tg and tpH4.5, favored post-acidification, exerted a bifidogenic effect, and preserved almost intact cell viability during storage. In addition, S. thermophilus was shown to stimulate the metabolism of the other lactic bacteria. Contrary to co-cultures, most of the effects in pure cultures were not statistically significant. The most important aspect of this paper is the use of the generation time as a tool to investigate the microbial response to inulin addition. 相似文献
992.
993.
Souto LI Minagawa CY Telles EO Garbuglio MA Amaku M Dias RA Sakata ST Benites NR 《The Journal of dairy research》2008,75(1):121-127
Mastitis is an inflammation of the mammary glands and in most cases it is caused by the presence of microorganisms. High mastitis rates in dairy cattle herds can cause an increase in total microorganism counts of bulk tank milk. The present paper was aimed at verifying whether the occurrence of mastitis in dairy cattle herds is reflected in raw-milk indicators of hygienic-sanitary quality. To observe the correlation among the analysed variables, we performed a logarithmical transformation (log10) of different indicator counts of raw milk and compared them with the occurrence of mastitis in dairy cattle herds. Few correlations were observed among mastitis cases in dairy cattle herds and the raw-milk indicators of hygienic-sanitary quality. We observed a negative correlation between the log10 of mesophilic aerobic plate counts and psychotropic aerobic plate counts when compared with the occurrence of no bacterial growth. The log10 of thermophilic aerobic plate counts and yeasts and mould aerobic plate counts presented a positive correlation with the cases of infectious mastitis and mastitis caused by Staphylococcus spp. 相似文献
994.
Heloisa Ramlow Roberta Karoline Morais Ferreira Cintia Marangoni Ricardo Antonio Francisco Machado 《International Journal of Applied Ceramic Technology》2019,16(6):2161-2172
Membrane distillation (MD) has been increasingly studied in the past decade for its potential as a separation process of nonvolatile components. The present study demonstrates a comprehensive overview of the current progress and challenges in the application of ceramic membranes to MD based on the available state of the art. There are already published review papers about MD, but the present study focuses on ceramic membranes, which are still the few used in MD when compared to polymeric membranes. Significant issues such as membrane material, module, characteristics, and hydrophobic modification are discussed. The main operating conditions and their effects on the separation process are given. Current applications of ceramic membranes in MD are also presented. Likewise, challenges and future perspectives associated with MD performance using ceramic membranes are highlighted. A review focused on ceramic membranes applied specifically to MD will contribute for future research in order that this process achieves successful implementation in industry. 相似文献
995.
Xanthine oxidase (XO) is the enzyme responsible for the catabolism of purines and their conversion into uric acid. XO is thus the target for the treatment of hyperuricemia and gout. For more than 50 years the only XO inhibitor drug available on the market was the purine analogue allopurinol. In the last decade there has been a resurgence in the search for new inhibitors of XO, as the activity of XO and hyperuricemia have also been associated with a variety of conditions such as diabetes, hypertension, and other cardiovascular diseases. In recent years the non-purine inhibitor febuxostat was approved in Europe and the USA for the treatment of hyperuricemia. This drug was followed by another XO inhibitor called topiroxostat. This review discusses the molecular structures and activities of the multiple classes of inhibitors that have been developed since the discovery of allopurinol, with a brief review of the molecular interactions between inhibitors and XO active site residues for the most important molecules. The challenges ahead for the discovery of new inhibitors of XO with novel chemical structures are discussed. 相似文献
996.
Anderson Veronese Odinei Marques Francisco Peñagaricano Rafael S. Bisinotto Ky G. Pohler Todd R. Bilby Ricardo C. Chebel 《Journal of dairy science》2019,102(7):6639-6648
Fertility traits were recently added to the evaluation of genetic merit, allowing for the selection of Holstein cattle with improved reproductive performance. In the current study, we investigated the associations among genomic merit for daughter pregnancy rate (GDPR) and heifer conception rate (GHCR) and physiological responses during proestrus and diestrus. Holstein heifers (n = 99) were classified based on GDPR [high = 3.26 ± 0.76 (1.6 to 5.3), n = 48; low = ?0.17 ± 0.75 (?1.8 to 1.0), n = 51] and GHCR [high = 2.75 ± 0.77 (1.5 to 5.5), n = 49; low = 0.06 ± 0.67 (?2.1 to 1.2), n = 50]. Heifers were fitted with an automated estrous detection device, were treated with PGF2α for synchronization of estrus, and received either artificial insemination or embryo transfer at detected estrus. Blood was sampled at the time of PGF2α treatment, within 24 h of the onset of estrus (d 0), and on d 7, 14, 19 ± 2, 28, and 35. Blood samples from all heifers were analyzed for concentrations of estradiol (d 0) and progesterone (on the day of PGF2α treatment and d 0, 7, and 14). Blood samples from heifers pregnant on d 38 ± 3 were analyzed for concentrations of progesterone (d 0, 7, 14, 19 ± 2, 28, and 35), pregnancy-specific protein B (d 19 ± 2, 28, and 35), and insulin-like growth factor 1 (d 0, 7, 14, 19 ± 2, 28, and 35). Expression of mRNA for interferon-stimulated gene 15 in peripheral leukocytes isolated from blood collected on d 19 ± 2 was determined. Ovaries were scanned by ultrasound daily from d 0 to 4 or until ovulation was detected. Heifers with low GHCR tended to be less likely to be detected in estrus (78.0 vs. 91.8%). Estradiol concentration on d 0 was greater for heifers with high GDPR (4.53 ± 0.23 vs. 3.79 ± 0.23 pg/mL). The ovulatory follicle was larger for heifers with high GDPR (16.28 ± 0.33 vs. 14.55 ± 0.35 mm), whereas heifers with high GHCR tended to have smaller ovulatory follicles (15.00 ± 0.31 vs. 15.83 ± 0.37 mm). Heifers with high GDPR tended to be more likely to ovulate within 96 h of the onset of estrus (90.7 vs. 75.0%). Among heifers pregnant on d 38 ± 3, GDPR and GHCR were not associated with mRNA expression for interferon-stimulated gene 15. Heifers with high GDPR had greater concentration of pregnancy-specific protein B from d 28 to 35 (3.03 ± 0.15 vs. 2.48 ± 0.1 ng/mL). Heifers with high GHCR tended to have greater insulin-like growth factor 1 concentration from d 7 to 35 (108.0 ± 3.2 vs. 97.7 ± 4.2 ng/mL). Our results suggest that selection for Holstein cattle for GDPR may have positive effects on reproductive performance through changes in ovarian follicle development and steroidogenesis. Although selection of Holstein cattle for GHCR may negatively affect estrous expression by affecting ovarian follicle growth, selection for GHCR may improve reproductive performance by altering the somatotropic axis. 相似文献
997.
Genetic parameters and morpho‐agronomic characterization of barley in the Brazilian Savannah
下载免费PDF全文
![点击此处可从《Journal of the Institute of Brewing》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Vitor Antunes Monteiro Renato Fernando Amabile Carlos Roberto Spehar Fábio Gelape Faleiro Eduardo Alano Vieira José Ricardo Peixoto Walter Quadros Ribeiro Junior Ana Paula Leite Montalvão 《Journal of the Institute of Brewing》2018,124(2):121-131
There is a growing demand for malting barley in the world and the supply relies on introducing the crop into new agricultural regions, such as the Brazilian Savannah. This requires selection for high yield and seed quality, critical factors for the success of commercial production. This study aimed at estimating genetic parameters associated with morpho‐agronomic characterization of 433 preliminarily selected accessions from a worldwide barley collection. The accessions were grown on a limed and fertilized Haplustox soil, using interpolated control experimental design, in the Savannah highlands, in Brazil. High‐magnitude heritability and genetic variation coefficients were found for agronomic traits, allowing the identification of genotypes for crossing schemes to generate high‐yield recombinants. Strong negative correlation between yield and number of days to heading and protein content indicated that selection should be directed at early‐maturity cultivars with desirable malting quality. The method proved efficient and revealed interesting indicators to be considered in barley breeding programmes directed at high‐quality malting production in the tropics. Copyright © 2018 The Institute of Brewing & Distilling 相似文献
998.
Aline Reyes‐Díaz Aarón F González‐Córdova Adrián Hernández‐Mendoza Ricardo Reyes‐Díaz Belinda Vallejo‐Cordoba 《International Journal of Dairy Technology》2018,71(1):1-9
Milk protein‐derived peptides have shown immunomodulatory properties either singly or in a mixture. However, information on the behaviour of these compounds is scarce, complicating their further study. This review presents current knowledge on immunomodulatory milk protein‐derived peptides, including hydrolysates, peptide fractions and single peptides. The evidence shows that hydrolysates derived from both casein and whey proteins show immunomodulatory effects; however, this bioactivity is mainly attributed to peptides derived from caseins. The identification of peptides in hydrolysates, as well as their characterisation and knowledge of the mechanisms behind their bioactivity, is necessary to further exploit their potential health benefits. 相似文献
999.
Gerson A. Oliveira Júnior Tatiane C.S. Chud Ricardo V. Ventura Dorian J. Garrick John B. Cole Danísio P. Munari José B.S. Ferraz Erik Mullart Sue DeNise Shannon Smith Marcos Vinícius G.B. da Silva 《Journal of dairy science》2017,100(12):9623-9634
The objective of this study was to investigate different strategies for genotype imputation in a population of crossbred Girolando (Gyr × Holstein) dairy cattle. The data set consisted of 478 Girolando, 583 Gyr, and 1,198 Holstein sires genotyped at high density with the Illumina BovineHD (Illumina, San Diego, CA) panel, which includes ~777K markers. The accuracy of imputation from low (20K) and medium densities (50K and 70K) to the HD panel density and from low to 50K density were investigated. Seven scenarios using different reference populations (RPop) considering Girolando, Gyr, and Holstein breeds separately or combinations of animals of these breeds were tested for imputing genotypes of 166 randomly chosen Girolando animals. The population genotype imputation were performed using FImpute. Imputation accuracy was measured as the correlation between observed and imputed genotypes (CORR) and also as the proportion of genotypes that were imputed correctly (CR). This is the first paper on imputation accuracy in a Girolando population. The sample-specific imputation accuracies ranged from 0.38 to 0.97 (CORR) and from 0.49 to 0.96 (CR) imputing from low and medium densities to HD, and 0.41 to 0.95 (CORR) and from 0.50 to 0.94 (CR) for imputation from 20K to 50K. The CORRanim exceeded 0.96 (for 50K and 70K panels) when only Girolando animals were included in RPop (S1). We found smaller CORRanim when Gyr (S2) was used instead of Holstein (S3) as RPop. The same behavior was observed between S4 (Gyr + Girolando) and S5 (Holstein + Girolando) because the target animals were more related to the Holstein population than to the Gyr population. The highest imputation accuracies were observed for scenarios including Girolando animals in the reference population, whereas using only Gyr animals resulted in low imputation accuracies, suggesting that the haplotypes segregating in the Girolando population had a greater effect on accuracy than the purebred haplotypes. All chromosomes had similar imputation accuracies (CORRsnp) within each scenario. Crossbred animals (Girolando) must be included in the reference population to provide the best imputation accuracies. 相似文献
1000.
Nerea Sanz‐Pintos Jara Pérez‐Jiménez Alejandro H. Buschmann José Rodrigo Vergara‐Salinas José Ricardo Pérez‐Correa Fulgencio Saura‐Calixto 《Journal of food science》2017,82(2):289-295
Seaweeds are rich in different bioactive compounds with potential uses in drugs, cosmetics and the food industry. The objective of this study was to analyze macromolecular antioxidants or nonextractable polyphenols, in several edible seaweed species collected in Chile (Gracilaria chilensis, Callophyllis concepcionensis, Macrocystis pyrifera, Scytosyphon lomentaria, Ulva sp. and Enteromorpha compressa), including their 1st HPLC characterization. Macromolecular antioxidants are commonly ignored in studies of bioactive compounds. They are associated with insoluble dietary fiber and exhibit significant biological activity, with specific features that are different from those of both dietary fiber and extractable polyphenols. We also evaluated extractable polyphenols and dietary fiber, given their relationship with macromolecular antioxidants. Our results show that macromolecular antioxidants are a major polyphenol fraction (averaging 42% to total polyphenol content), with hydroxycinnamic acids, hydroxybenzoic acids and flavonols being the main constituents. This fraction also showed remarkable antioxidant capacity, as determined by 2 complementary assays. The dietary fiber content was over 50% of dry weight, with some samples exhibiting the target proportionality between soluble and insoluble dietary fiber for adequate nutrition. Overall, our data show that seaweed could be an important source of commonly ignored macromolecular antioxidants. 相似文献