全文获取类型
收费全文 | 8824篇 |
免费 | 109篇 |
国内免费 | 11篇 |
专业分类
电工技术 | 123篇 |
综合类 | 55篇 |
化学工业 | 1793篇 |
金属工艺 | 176篇 |
机械仪表 | 228篇 |
建筑科学 | 223篇 |
矿业工程 | 17篇 |
能源动力 | 308篇 |
轻工业 | 1418篇 |
水利工程 | 68篇 |
石油天然气 | 50篇 |
无线电 | 431篇 |
一般工业技术 | 1124篇 |
冶金工业 | 2070篇 |
原子能技术 | 58篇 |
自动化技术 | 802篇 |
出版年
2024年 | 120篇 |
2023年 | 108篇 |
2022年 | 215篇 |
2021年 | 367篇 |
2020年 | 266篇 |
2019年 | 309篇 |
2018年 | 310篇 |
2017年 | 332篇 |
2016年 | 289篇 |
2015年 | 222篇 |
2014年 | 307篇 |
2013年 | 549篇 |
2012年 | 429篇 |
2011年 | 461篇 |
2010年 | 330篇 |
2009年 | 363篇 |
2008年 | 321篇 |
2007年 | 275篇 |
2006年 | 224篇 |
2005年 | 148篇 |
2004年 | 148篇 |
2003年 | 150篇 |
2002年 | 122篇 |
2001年 | 80篇 |
2000年 | 85篇 |
1999年 | 127篇 |
1998年 | 591篇 |
1997年 | 388篇 |
1996年 | 271篇 |
1995年 | 172篇 |
1994年 | 140篇 |
1993年 | 145篇 |
1992年 | 37篇 |
1991年 | 43篇 |
1990年 | 56篇 |
1989年 | 46篇 |
1988年 | 51篇 |
1987年 | 38篇 |
1986年 | 32篇 |
1985年 | 27篇 |
1984年 | 7篇 |
1983年 | 7篇 |
1982年 | 14篇 |
1981年 | 14篇 |
1980年 | 16篇 |
1978年 | 11篇 |
1977年 | 39篇 |
1976年 | 102篇 |
1975年 | 8篇 |
1974年 | 8篇 |
排序方式: 共有8944条查询结果,搜索用时 15 毫秒
41.
Fabiane Picinin De Castro-Cislaghi Carina Dos Reis E Silva Carlise Beddin Fritzen-Freire Juliana Goulart Lorenz Ernani S. Sant’Anna 《Journal of food engineering》2012
Bifidobacterium Bb-12 was microencapsulated by spray drying with whey. This present work investigated the survival of these microcapsules under simulated gastrointestinal conditions, as well as their tolerance to NaCl and their viability during storage. The results showed a small decrease in the viability of microencapsulated Bifidobacterium at low pH. In relation to the exposure of Bifidobacterium to bile, microencapsulation with whey did not protect the probiotic cells; however, the viability of the microcapsules remained >6 log cfu/g, even after 24 h of incubation at the highest bile concentration analyzed. No growth was noted with either the free cells or the microencapsulated cells on MRS-LP with NaCl. The viability of the microcapsules stored at 4 °C remained high and constant for 12 weeks. When the microcapsules were added to a dairy dessert, the probiotic count remained above 7 log cfu/g for 6 weeks. Therefore, whey is a promising encapsulating agent for Bifidobacterium Bb-12. 相似文献
42.
43.
Ludmilla Santos Silva de Mesquita Tássio Rômulo Silva Araújo Luz José Wilson Carvalho de Mesquita Denise Fernandes Coutinho Flavia Maria Mendonça do Amaral Maria Nilce de Sousa Ribeiro 《Food Reviews International》2019,35(2):105-131
Lamiaceae is among the largest families of flowering plants with about 250 genera and over 7,000 species distributed around the world. It is considered as the important source of essential oils, for example, menthol, geraniol, eucalyptol, camphor and thymol. Therefore, it is imperative to study these economically important compounds under in vitro conditions for their sustainable and enhanced production. In addition to proven biological activities, essential oils from this family have recently been evaluated for anticancer activities and considered as a source of anticancer drugs. Mechanisms involved in the essential oils-mediated antiproliferative activity include cell cycle arrest, apoptosis and DNA repair mechanisms. Essential oils also act in the reduction of tumors, inhibiting metastasis and as anti-multidrug resistance molecules. The aim of this review is to assess the anticancer properties of essential oils obtained from different members of family Lamiaceae. The available reports on active components of essential oils and their effect on cancer type and cell line have been discussed. Biotechnological studies to improve the production of essential oils have also been highlighted. Various methods have been adopted to obtain essential oils under in vitro conditions from different plant species of family Lamiaceae, and their production is affected by culture conditions, cultivation mode, utilization of nutrient media and plant growth regulators. The literature survey suggests that essential oils obtained from family Lamiaceae have perspective for the development of new alternatives for disease treatment and prevention. 相似文献
44.
Rocío Santander Werner Creixell Elizabeth Sánchez Gerda Tomic José R. Silva Cristian A. Acevedo 《Food and Bioprocess Technology》2013,6(12):3345-3352
Beef from cattle less than 30 months old at the point of slaughter are generally sold in meat markets. Though the age of the animal can generally be estimated by dentition, this method cannot be applied to a carcass or a piece of meat from which the teeth have been removed. Since gas chromatography of volatile organic compounds has been used to classify biological samples, this technique was used for classifying meat obtained from cattle aged over 30 months (OTM) at point of slaughter. Volatile organic compounds of fresh meat (M. longissimus dorsi) samples obtained from cattle of different age and dentition (two, four, and six teeth) at point of slaughter were analyzed using gas chromatography/mass spectrum (GC/MS). Six volatile organic compounds were selected (hexanoic acid, benzoic acid, octanoid acid, tridecane, tetradecane, and 4-formylbenzoic acid) and confirmed by using chemical standards and Kovat’s indexes. The chromatogram data were used to train two classifiers, one based on the partial least square (PLS) method and another based on support vector machine (SVM), but only SVM showed high accuracy. Data exploration based on the principal component analysis allowed for comprehension of the data distribution, proposing a new version of PLS in a parallel configuration. This modified version of the PLS algorithm showed better accuracy than the SVM classifier. In conclusion, volatile organic compounds analyzed by GC/MS–solid-phase microextraction can be used to recognize OTM beef. 相似文献
45.
Karina Cardoso Tramonte João Gustavo Provesi Iolanda Moreira Dutra Albuquerque E Silva Aureanna Nairne Negrão Murakami Marcelo Maraschin Renata Dias De Mello Castanho Amboni Edna Regina Amante 《International Journal of Food Science & Technology》2011,46(9):1871-1877
The heart of palm is a food extracted from several species of palm trees. Only 10–20% of the raw material is transformed into canned hearts of palm, therefore this agro‐industry generates a large quantity of solid residue. The aim of this work was to extract and characterise a juice produced from this solid residue. This extract is compared with the traditional fruit juices (orange and pineapple juices), obtaining higher contents of minerals, such as magnesium (22.80 mg/100 g) and potassium (276.90 mg/100 g), phenolic compounds (gallic, 3,4‐dihydroxybenzoic, chlorogenic, syringic and caffeic acids) and high free radical scavenging capacity (expressed as 2,2‐diphenyl‐1‐picrylhydrazyl), which suggest high antioxidant activity. Additionally, a new soft drink was formulated using this king palm juice as its main ingredient. The soft drink samples formulated with this juice had high sensory acceptability and high intention of consumption, which suggests an important and low‐cost application for this industrial residue. 相似文献
46.
Sensory Analysis and Consumers Studies of Açai Beverage After Thermal,Chlorine and Ozone Treatments of the Fruits
下载免费PDF全文

47.
Federico Ferreres Alberto Ortiz Carmen Silva Christina Garcia-Viguera Francisco A. Tomás-Barberán Francisco Tomás-Lorente 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1992,194(2):139-143
Summary The flavonoids present in ten selected samples of La Alcarria honey with different pollen compositions have been HPLC analysed in order to establish if correlations between botanical origin and flavonoid profiles are possible. A common flavonoid pattern is observed in the different samples showing that pollen is not the main source of honey flavonoids. A close correlation between the flavonoid patterns of honey flavonoids and propolis flavonoids has been found suggesting that flavonoid analysis could be more useful in geographical origin determinations than in botanical origin studies.
Flavonoide des La-Alcarria-Honigs Eine Studie ihres botanischen Ursprungs
Zusammenfassung Die Flavonoide in Proben in Alcarria-Honig mit unterschiedlicher Pollenzusammensetzung wurden untersucht, um Kortrelationen zwischen dem botanischen Ursprung und den möglichen Flavonoiden zu finden. In den verschiedenen Proben wurde ein Flavonoid-Muster gefunden, wobei der Pollen nicht die Hauptquelle der Honigflavonoide ist. Es wurde jedoch eine enge Korrelation zwischen den Flavonoid-Mustern des Honigs und des Bienenkittharzes gefunden, was für die geographische Herkunft wichtiger ist als die botanische.相似文献
48.
The application of an enzymatic pre-treatment to increase the yield of grape seed oil extraction was studied. Experiments were carried out to measure the effects that reaction time, temperature, pH, particle size and enzyme concentration have upon the enzymatic activity. 相似文献
49.
The elemental composition of different types of keratohyalin granules from the epidermis of newborn and adult rats was studied by means of an EMMA-4 analytical electron microscope, equipped with an energy-dispersive X-ray spectrometer. An absolute quantitation of the sulphur concentration in keratohyalin granules was performed. The results demonstrate that epidermal keratohyalin granules are chemically heterogeneous. A type of keratohyalin granule present in the nuclei and cytoplasm of epidermal cells from both newborn and adult rats - termed single granules - is rich in sulphur, having a content of 2-5-3-6%. Other types of keratohyalin granules, which differ in newborn and adult rats, contain a sulphur-poor component; they often have a sulphur-rich component as well. The sulphur-poor keratohyalin contains 0-6-0-9% sulphur. It is suggested that the sulphur-rich keratohyalin granules are the source of the peripheral envelope protein of cornified cells. 相似文献
50.