全文获取类型
收费全文 | 59149篇 |
免费 | 3005篇 |
国内免费 | 79篇 |
专业分类
电工技术 | 419篇 |
综合类 | 133篇 |
化学工业 | 13024篇 |
金属工艺 | 1135篇 |
机械仪表 | 1218篇 |
建筑科学 | 1755篇 |
矿业工程 | 137篇 |
能源动力 | 1466篇 |
轻工业 | 10371篇 |
水利工程 | 572篇 |
石油天然气 | 299篇 |
武器工业 | 7篇 |
无线电 | 2351篇 |
一般工业技术 | 9416篇 |
冶金工业 | 11618篇 |
原子能技术 | 265篇 |
自动化技术 | 8047篇 |
出版年
2024年 | 119篇 |
2023年 | 534篇 |
2022年 | 1078篇 |
2021年 | 1736篇 |
2020年 | 1266篇 |
2019年 | 1434篇 |
2018年 | 2222篇 |
2017年 | 2193篇 |
2016年 | 2316篇 |
2015年 | 1691篇 |
2014年 | 2219篇 |
2013年 | 4578篇 |
2012年 | 3554篇 |
2011年 | 3515篇 |
2010年 | 2833篇 |
2009年 | 2568篇 |
2008年 | 2464篇 |
2007年 | 2173篇 |
2006年 | 1625篇 |
2005年 | 1377篇 |
2004年 | 1220篇 |
2003年 | 1187篇 |
2002年 | 1042篇 |
2001年 | 816篇 |
2000年 | 728篇 |
1999年 | 793篇 |
1998年 | 3721篇 |
1997年 | 2473篇 |
1996年 | 1638篇 |
1995年 | 969篇 |
1994年 | 747篇 |
1993年 | 792篇 |
1992年 | 306篇 |
1991年 | 281篇 |
1990年 | 223篇 |
1989年 | 242篇 |
1988年 | 243篇 |
1987年 | 218篇 |
1986年 | 182篇 |
1985年 | 213篇 |
1984年 | 189篇 |
1983年 | 136篇 |
1982年 | 169篇 |
1981年 | 189篇 |
1980年 | 215篇 |
1979年 | 102篇 |
1978年 | 101篇 |
1977年 | 349篇 |
1976年 | 742篇 |
1973年 | 94篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
Effects of novel nitrite packaging film on the bacterial growth of bison strip‐loin steaks 下载免费PDF全文
993.
994.
Extruded snacks from whole wheat supplemented with textured soy flour: Effect on instrumental and sensory textural characteristics 下载免费PDF全文
995.
996.
Effects of ethyl-3-nitrooxy propionate and 3-nitrooxypropanol on ruminal fermentation,microbial abundance,and methane emissions in sheep 总被引:1,自引:0,他引:1
G. Martínez-Fernández L. Abecia A. Arco G. Cantalapiedra-Hijar A.I. Martín-García E. Molina-Alcaide M. Kindermann S. Duval D.R. Yáñez-Ruiz 《Journal of dairy science》2014
The aim of this work was to investigate the effect of feeding ethyl-3-nitrooxy propionate (E3NP) and 3-nitrooxypropanol (3NP), 2 recently developed compounds with potential antimethanogenic activity, in vitro and in vivo in nonlactating sheep on ruminal methane production, fermentation pattern, the abundance of major microbial groups, and feed degradability. Three experiments were conducted, 1 in vitro and 2 in vivo. The in vitro batch culture trial (experiment 1) tested 2 doses of E3NP and 3NP (40 and 80 μL/L), which showed a substantial reduction of methane production (up to 95%) without affecting concentration of volatile fatty acids (VFA). The 2 in vivo trials were conducted over 16 d (experiment 2) and 30 d (experiment 3) to study their effects in sheep. In experiment 2, 6 adult nonpregnant sheep, with permanent rumen cannula and fed alfalfa hay and oats (60:40), were treated with E3NP at 2 doses (50 and 500 mg/animal per day). After 7, 14, and 15 d of treatment, methane emissions were recorded in respiration chambers and rumen fluid samples were collected for VFA analysis and quantification of bacterial, protozoal, and archaeal numbers by real-time PCR. Methane production decreased by 29% compared with the control with the higher dose of E3NP on d 14 to 15. A decrease in the acetate:propionate ratio was observed without detrimental effects on dry matter intake. In experiment 3, 9 adult nonpregnant sheep, with permanent rumen cannula and fed with alfalfa hay and oats (60:40), were treated with E3NP or 3NP at one dose (100 mg/animal per day) over 30 d. On d 14 and d 29 to 30, methane emissions were recorded in respiration chambers. Rumen fluid samples were collected on d 29 and 30 for VFA analysis and quantification of bacterial, protozoal, and archaeal numbers by real-time PCR. In addition, on d 22 and 23, samples of oats and alfalfa hay were incubated in the rumen of sheep to determine dry matter ruminal degradation over 24 and 48 h, respectively; no effect was observed (78.6, 78.3, and 78.8% of alfalfa and 74.2, 74.0, and 70.6% of oats in control, E3NP, and 3NP groups, respectively). A reduction in methane production was observed for both additives at d 14 and d 29 to 30. In both treatments, the acetate:propionate ratio was significantly decreased. Likewise, total concentrations of the analyzed microbial groups in the rumen showed no difference among treatments and doses for both experiments. Both tested compounds showed promise as methane inhibitors in the rumen, with no detrimental effects on fermentation or intake, which would need to be confirmed in lactating animals. 相似文献
997.
Inés María López-Calleja Silvia de la CruzNicolette Pegels Isabel GonzálezRosario Martín Teresa García 《LWT》2014
Almond has been widely used in all sorts of food products, mostly due to its pleasant flavor and health benefits. However almonds can become an important health problem since they are responsible for triggering adverse immune responses in allergic individuals, and since they are present in many processed foods they are considered as a potential hidden allergen. Consequently, it's important for food processors and regulatory agencies to be able to ensure accurate labeling of foods to protect the safety of the public and to avoid expensive recalls. We propose a simple and highly sensitive approach to detect almond in a wide range of processed foods. The method consists of a real-time PCR assay targeting the gene encoding for the ITS1 in almond, using a nuclease (TaqMan) probe labeled with FAM and BBQ. Sensitivity of real time PCR was determined by analysis of raw and heat treated almond-wheat flour mixtures with a range of detection of 0.1–100,000 mg/kg. The assay was successfully trialed on a total of 214 commercial foodstuffs allowing the detection of trace amounts of almond down to the level of 0.1 mg/kg, and is therefore proposed as a ready-to-use analytical tool to trace almond allergens in foods. 相似文献
998.
The objective of this study was to evaluate the effect of the incorporation of spirulina on technological and nutritional quality of dried pasta. Wheat flour was substituted by spirulina biomass at three levels: 5, 10 and 20 g/100 g, and a sample without spirulina biomass was made as control. The technological quality was analyzed in terms of cooking properties and texture profile, while pasta surface was observed by confocal microscopy. In addition, protein content, in vitro protein digestibility, phenolic compound content and in vitro antioxidant activity were the major bio-functional characteristics measured. An in vitro starch digestion was performed in order to estimate the glycemic index. Only pasta with 20 g of spirulina / 100 g of flour did slightly modify technological quality parameters; microstructure studies revealed the impact of spirulina addition, resulting in a more heterogeneous surface. The glycemic index was not affected by the addition of spirulina. The incorporation of spirulina resulted in an increase of protein content; however, protein digestibility was reduced as microalgae content increased. Pasta with spirulina exhibited high phenolic compounds content and antioxidant activity compared to control pasta, which could be used to enhance the nutritional profile of the product. 相似文献
999.
The use of cheese whey and probiotic cultures in the production of dairy beverages has been highly attractive; nonetheless, whey-based goat beverages tend to be poor and watery when compared to fermented milks. The addition of fruits and fibre ingredients might improve texture and mouthfeel of this kind of product. Fermented whey-based goat beverages prepared using Streptococcus thermophilus TA-40 as starter culture, with added guava or soursop pulps, and with or without addition of partially hydrolysed galactomannan from Caesalpinia pulcherrima seeds (PHGM), showed to be good vehicles for Bifidobacterium animalis subsp. lactis BB-12 and Lactobacillus rhamnosus Lr-32, maintaining their viability above 7 log CFU/ml during 21 days. PHGM increased the dietary fibre content and enhanced the instrumental texture and sensory features of both guava and soursop dairy beverages, especially texture, appearance, and overall acceptability. The PHGM might be recommended to improve nutritional and sensory quality of fermented probiotic beverages produced with goat milk and cheese whey. 相似文献
1000.
E.N. Andrade A. Polizel Neto R.O. Roça M.H. Faria F.D. Resende G.R. Siqueira R.S.B. Pinheiro 《Meat science》2014
This work evaluated the beef quality parameters of 108 bulls randomly administered to three treatments during rearing in pastures and two treatments during fatting in feedlots, including mineral and rumen-protected lipids. Meat and fat color, cooking yield, shear force, sensorial traits and chemical and fatty acid compositions were evaluated. Generally, the beef quality parameters were not affected by the rumen protected lipids; however, supplementation with rumen-protected lipids during the rearing period yielded darker beef and brighter fat and increased beef tenderness in meat aged for 28 days compared to the meat from animals that received only mineral supplementation. In addition, the percent of meat polyunsaturated fatty acids was negatively affected by the inclusion of protected lipids, yielding 5.58 and 3.72% in animals fed with and without rumen-protected lipids, respectively, during the fatting period. 相似文献