首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   4374篇
  免费   750篇
  国内免费   537篇
林业   14篇
农学   91篇
基础科学   44篇
  159篇
综合类   850篇
农作物   87篇
水产渔业   4061篇
畜牧兽医   330篇
园艺   4篇
植物保护   21篇
  2024年   44篇
  2023年   78篇
  2022年   100篇
  2021年   181篇
  2020年   256篇
  2019年   323篇
  2018年   234篇
  2017年   336篇
  2016年   270篇
  2015年   201篇
  2014年   239篇
  2013年   387篇
  2012年   273篇
  2011年   309篇
  2010年   222篇
  2009年   194篇
  2008年   181篇
  2007年   203篇
  2006年   168篇
  2005年   171篇
  2004年   151篇
  2003年   129篇
  2002年   97篇
  2001年   140篇
  2000年   117篇
  1999年   94篇
  1998年   54篇
  1997年   76篇
  1996年   84篇
  1995年   71篇
  1994年   62篇
  1993年   54篇
  1992年   45篇
  1991年   28篇
  1990年   20篇
  1989年   31篇
  1988年   12篇
  1987年   11篇
  1986年   13篇
  1985年   1篇
  1981年   1篇
排序方式: 共有5661条查询结果,搜索用时 304 毫秒
941.
ABSTRACT

Yogurt is a traditional dairy product widely consumed all over the world. Syneresis, which is a result of lower water holding capacity, is a big concern and an important quality parameter. In this study, the efficiency of locust bean gum and different gelatins (fish skin, fish scale, and bovine skin) in preventing syneresis was investigated. Samples were stored at 4°C for 2 weeks, a typical shelf life of yogurt, and analyzed periodically for quality parameters. Syneresis, viscosity, and water holding capacity of the control and gum added samples were almost identical, while gelatin added samples were generally significantly improved (p < 0.05).  相似文献   
942.
943.
944.
The main objective of the current work was to evaluate the proximate chemical composition and nutritional quality of amino acids of protein hydrolysates from viscera of Tilapia nilotica fish. The results of amino acid composition showed that all hydrolysates contained sufficient and/or excessive amounts of both essential and nonessential amino acids, with appreciable values of essential amino acid/nonessential amino acid ratio (0.77 to 1.59) and essential amino acid/total amino acid ratio (43.35 to 61.35). All protein hydrolysates had a high content of the flavor enhancer amino acids. The lowest values of essential amino acids were found for phenylalanine and methionine with chemical scores ranging from 0.04 to 0.77 and 0.09 to 1.06, respectively, except for 18 h hydrolysates. The protein efficiency ratio had values greatly exceeding 2.0, which is considered a high quality. On the other hand, the levels of sugar and ash contents ranged from 2.69 to 3.32 g L?1 and 0.48 to 2.1%, respectively, with 9.2 to 14% dry matter. Mineral composition showed that sufficient amounts of calcium, sodium, potassium, magnesium, and iron were present. The results suggest that the studied hydrolysates are appropriate for use in balanced human or animal diets.  相似文献   
945.
ABSTRACT

Extrusion cooking plays an important role in the production of puffed snacks, which enjoy wide acceptance all over the world and are potential vehicles for increasing the consumption of n-3 fatty acids. Response surface methodology (RSM) with central composite design was adopted to investigate the effects of four independent variables (fish powder, fish oil, moisture, and screw speed) at five levels on expansion ratio, breaking strength index, hardness, color, and thiobarbituric acid reactive substances (TBARS). A second order polynomial model was used to study the main, interactive, and quadratic effects of the independent variables and to explain the relationship between the responses and independent variables. Moisture was found to be the most significant factor (p < 0.001) influencing expansion ratio, breaking strength index, and color. Inclusion of fish powder and fish oil were found to be negatively associated with the expansion characteristics, resulting in decreased lipid oxidation due to less exposed surface area of the extrudates to air. Further, the absence of linear effect of fish powder and fish oil on TBARS demonstrated the possibility to incorporate higher levels of these ingredients to produce oxidatively stable extruded snacks rich in fish proteins.  相似文献   
946.
Fatty fish have been recognized as potential raw material for production of minced meat; however, they are prone to oxidation and further deterioration. In the present study, the effect of washing and antioxidant (tannic acid) treatment on the quality of minced meat of Trachurus trachurus (horse mackerel) during frozen storage was observed. Minced meat of Trachurus trachurus was divided into three lots (T0, T1, and T2). T1 was washed with cold water, T2 with cold water containing tannic acid (100 mg/kg), and T0 was not washed. All the lots were frozen at ?40°C and stored at ?20 ± 2°C for 125 days and were subjected to biochemical, microbiological, and sensory evaluation at regular intervals of 25 days. The antioxidant treatment with tannic acid at the dosage used was found effective in minimizing the rancidity problems of minced meat (T2), compared to T0 and T1. During the whole period of storage, samples from T2 showed good quality in terms of microbiological, biochemical, and sensory analysis compared to T1 and T0.  相似文献   
947.
Response surface methodology (RSM) was employed to maximize the removal of phospholipids (PLs) and other chemical hazards in tilapia protein isolates made from tilapia frame (TF). CaCl2 and the ratio of water to minced tilapia frame (W:TF) were the significant variables affecting PLs reduction. The optimum condition for maximal PLs reduction (90.0%) was: 10.25 mM CaCl2 and a W:TF of 7.8:1, while other variables were fixed at 5 mM citric acid, 60 min incubation, pH 11, and centrifugal speed of 8,000 × g. At these conditions, the great reduction of lipids (93.9%), Hg (97.6%), and As (95.5%), as well as 86.1% of protein recovery, were obtained. Protein isolates with significantly reduced chemical hazards and lipids were successfully prepared from tilapia frames using the alkaline extraction assisted with CaCl2 and citric acid.  相似文献   
948.
ABSTRACT

Malnutrition in children is a current global burden. A common snack for children is biscuits prepared from cereals. However, these types of biscuits have low protein content. Therefore, producing healthier biscuits enriched with essential amino acids (EAAs) and other micronutrients is of great interest to researchers and manufacturers. In this study, biscuits produced from low gluten wheat flour fortified with sturgeon fillet powder (SFP) in various mixing ratios (100:0, 95:5, 93:7, and 90:10, respectively) were investigated. The results revealed that the nutritional and proximate composition of biscuits were significantly (P ≤ 0.05) improved: moisture (6.77 ± 0.06–7.65 ± 0.06), protein (13.23 ± 0.35–17.12 ± 0.02), fat (15.57 ± 0.18–15.85 ± 0.25), ash (0.84 ± 0.07–0.92 ± 0.06), spread ratio (14.0 ± 0.92–14.33 ± 0.21), and hardness (2,057.90 ± 28.33–3,089.02 ± 51.53). Total amino acids were 6.91, 9.34, 10.32, and 10.58; and EAAs were 2.43, 3.97, 4.48, and 4.22 g/100 g for 0%, 5%, 7%, and 10% SFP, respectively. Leucine was the major amino acid with 5% and 10% SFP, while methionine was the major amino acid with 7% SFP. Fungal counts were not observed, and quality indices were below the maximum acceptable limits in the products. Biscuits supplemented with 7% SFP showed the highest sensory evaluation score. Overall, the inclusion of 7% SFP could produce protein enriched cereal-based fortified biscuits with acceptable sensory and quality attributes and ultimately could insure effective fish utilization and solve malnutrition problems.  相似文献   
949.
ABSTRACT

This work aimed to evaluate the physicochemical and functional properties of proteins recovered from whitemouth croaker (Micropogonias furnieri) and Argentine anchovy (Engraulis anchoita) residues obtained by the process of acid solubilization using HCl at pH = 2 and alkaline solubilization using NaOH at pH = 12 and isoelectric precipitation (pH = 5.5). The proximate composition and functional properties were determined. The solubilization and water holding capacity (WHC) of the recovered protein were studied in the pH range of 3, 5, 7, 9, and 11. The high protein content and lowest lipid reduction presented by the protein recovered from the whitemouth croaker residue and obtained by the acid solubilizing process was 97.1 and 98.4%, respectively. The maximum solubilized protein was at pH 3 and 11, and the minimum solubilized protein was at pH 5 for both species. The greater ability to retain oil was observed for the alkaline solubilization process (8.3 and 7.3). The lower WHC was at pH 5. The acid and alkali residue concentrates of the whitemouth croaker presented higher WHC at pH 3 and 11. These proteins can be used in preparing edible films and have been used to produce bioactive compounds for supplements or functional ingredients.  相似文献   
950.
ABSTRACT

Our objective was to produce a unique feed ingredient from underutilized walleye pollock (Theragra chalcogramma) and pink salmon (Oncorhynchus gorbuscha) testes. Protein content in meals from both species (72% and 80%, respectively) were above the values found in high quality herring meals (~70%), but both were poor in some essential amino acids, e.g., methionine. Additionally, both were good sources of the amino acid taurine (1.7 and 2.2% of meal, respectively). Pollock meal was very rich in phospholipids (82% of total lipids) and in DHA (28 mg/g meal) and EPA (18 mg/g meal), indicating potential as an ingredient in larval starter diets. The purine contents in both pollock and salmon testes meals were more than 10 times the concentrations found in other fish byproducts or commercial fishmeals. The high concentrations of purines found in these testes, especially in the salmon meal, make it an ideal candidate for an immune system stimulant when added to dietary formulations.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号