全文获取类型
收费全文 | 288篇 |
免费 | 24篇 |
专业分类
林业 | 22篇 |
农学 | 7篇 |
基础科学 | 7篇 |
65篇 | |
综合类 | 8篇 |
农作物 | 41篇 |
水产渔业 | 40篇 |
畜牧兽医 | 97篇 |
园艺 | 7篇 |
植物保护 | 18篇 |
出版年
2023年 | 2篇 |
2022年 | 9篇 |
2021年 | 15篇 |
2020年 | 14篇 |
2019年 | 18篇 |
2018年 | 27篇 |
2017年 | 29篇 |
2016年 | 22篇 |
2015年 | 6篇 |
2014年 | 18篇 |
2013年 | 17篇 |
2012年 | 16篇 |
2011年 | 18篇 |
2010年 | 21篇 |
2009年 | 6篇 |
2008年 | 17篇 |
2007年 | 10篇 |
2006年 | 4篇 |
2005年 | 5篇 |
2004年 | 9篇 |
2003年 | 2篇 |
2002年 | 5篇 |
2001年 | 3篇 |
2000年 | 4篇 |
1998年 | 2篇 |
1997年 | 4篇 |
1996年 | 4篇 |
1994年 | 1篇 |
1989年 | 1篇 |
1985年 | 1篇 |
1977年 | 1篇 |
1974年 | 1篇 |
排序方式: 共有312条查询结果,搜索用时 125 毫秒
41.
42.
This study was undertaken to establish the relationships among 44 chickpea (Cicer) accessions from a minicore collection including 30 cultivars, seven landraces from C. arietinum and seven accessions from C. reticulatum, C. echinospermum, and C. oxyodon species, all with economically important traits and tolerance to biotic and abiotic stresses, by using six amplified fragment length polymorphism (AFLP) primer combinations. The reaction products were resolved on MetaPhor agarose gel. A total of 64 clear and reproducible AFLP markers were recorded. Mean of polymorphism information content (PIC) values were calculated for each primer pair which ranged from 0.155 (EcoRI-ACC/MseI-CAG) to 0.270 (EcoRI-ACC/ MseI-CTG) with an average of 0.237. Analysis of molecular variance revealed that 90% of the total variance was due to differences within populations and 10% due to differences among populations. The results showed that the studied minicore collection is highly variable and could be used as the fundamental base in chickpea breeding programs. 相似文献
43.
Hamid Reza Jamalzadeh Maryam Akhundian Milad Kabir Hossein Khara Saeed Hajirezaee 《Aquaculture Research》2014,45(6):1090-1095
In this study, the relationships between the seminal fluid sex steroids sperm quality parameters (i.e. sperm motility and sperm production were investigated in the endangered Caspian brown trout. According to results, the variation of sex steroid concentrations was comparatively high. The seminal fluid levels of 17α‐Hydroxyprogesterone (OHP) had positive correlation with percentage and duration of sperm motility. Similar correlation was found between the seminal fluid concentration of testosterone (T) and estradiol‐17β (E2) with sperm concentration. As well as, there was no significant correlation between progesterone (P) with sperm quality indices. The significant correlation of some steroids i.e. OHP, T and E2 and sperm quality parameters of Caspian brown trout confirms the key role of these steroids in acquisition of the potential of motility during final stage of the maturation. 相似文献
44.
45.
Saeed Hajirezaee Bagher Mojazi Amiri Ali Reza Mirvaghefi 《Journal Of Applied Aquaculture》2013,25(2):157-170
This study was carried out to evaluate milt quality in male Caspian brown trout (Salmo trutta caspius) over the course of the winter spawning season. Milt samples were collected biweekly during December and January. Chemical composition of seminal fluid, sperm production (milt volume, sperm density, spermatocrit,) and sperm motility characteristics (percentage and duration of motility) were measured. Milt volume, sperm density, osmolality, seminal minerals (Ca2+, Mg2+, K+, Na+, Cl?), and total protein gradually decreased over the spawning season. Glucose and triglyceride content of milt did not show significant changes over the spawning season. Milt pH and the percentage and duration of motility were comparatively stable, declining only at the end of the season. Significant positive correlations were found between sperm density and seminal minerals, total protein and spermatocrit; percentage of motile spermatozoa and seminal minerals, total protein; and duration of motility and K+, Cl?, total protein, and pH. Results show that season has a significant influence on milt quality in male Caspian brown trout, with the best milt being available at the beginning of spawning season. 相似文献
46.
Parisa Maleki Saeed Saadat Forood Sharifi Farhad Dehghany Masomeh Salehi 《Communications in Soil Science and Plant Analysis》2018,49(15):1815-1825
Salinity is one of the major agricultural problems in arid and ?semi-arid regions. Considering the variation of plant’s ?sensitivity to salinity during growth, a greenhouse study with completely randomized design? was conducted to determine the relative salinity tolerance of Quinoa (Chenopodium quinoa Willd.) at different growth stages from seedling establishment to maturity (establishment, flowering and seed filling) by evaluating the Salinity Threshold Value (STV). Eight levels of ECi (i.e., Non-saline, 2, 4, 8, 12, 15, 20, 25 dSm?1) with four replications and five levels (i.e., Non-saline, 10, 15, 20, 25 dSm?1) with three triplications were applied at first and two last growth stages, respectively. A ?comparison was performed on some growth and yield parameters of plants irrigated by considering STV (T) and ?plants irrigated permanently by mentioned salinity levels regardless of STV (P) to choose ?which method (P or T) is better at each salinity level. The STV was ?evaluated 8, 20 and 15 dSm?1 at each growth stage, respectively. Seedling of Quinoa was more sensitive to salinity than the mature plant. Therefore, after establishment Quinoa has the ?feasibility of irrigation by high-saline waters. The (P) ?method was suitable only if the freshwater was available during all growth period of the plant; otherwise at higher salinities irrigation should be performed by considering STV (T method) to minimize the intensity of growth and yield reduction and to prevent yield loss at very high salinities. To achieve this, if high-saline water is available it’s possible to ?use plant propagation techniques or cultivating Quinoa simultaneously with seasonal rainfall.? 相似文献
47.
Sidra Kanwal Sumera Shabir Maimona Saeed Robina Gul Maryum Zahoor 《Journal of plant nutrition》2018,41(4):526-538
Salinity is a major abiotic stress that affects crop production throughout the world. Biochar is an activated carbon soil conditioner that can alleviate the negative impacts of salinity. The research was conducted to evaluate the ameliorative effect of 1% and 2% of biochar application on wheat seed germination and growth attributes under salinity. Both levels of biochar improved the germination and growth conditions under salinity; however, 2% biochar level was more effective compared to 1% level. Root and shoot length increased up to 23% and11% with 2% biochar, respectively. The maximum increase of 16% and 10% in leaf water potential and osmotic potential was noted with 2% biochar at 150 mM salt. The decrease in proline content and soluble sugar at 2% biochar was 51% and 27%, respectively. Decrease in superoxide dismutase activity was 15.3% at 2% level of biochar under stress biochar mitigates the negative effects of salinity and improved wheat productivity. 相似文献
48.
Effects of physical form of starter and forage provision to young calves on blood metabolites,liver composition and intestinal morphology 下载免费PDF全文
H. Moeini A. H. Mahdavi A. Riasi G. R. Ghorbani E. Oskoueian M. A. Khan M. H. Ghaffari 《Journal of animal physiology and animal nutrition》2017,101(4):755-766
This study evaluated the effects of physical form of starter feed and forage provision on the performance, blood metabolites, liver composition and intestinal morphology of dairy calves. Individually housed calves (n = 52; body weight = 41.5 ± 2.5 kg) were randomly allocated (n = 13 per treatment) to one of the following four treatments: (i) ground starter feed (GS; mean particle size = 0.72 mm in diameter), (ii) textured starter feed (TS; mean particle size = 3.61 mm in diameter, including steam‐flaked corn and barley), (iii) pelleted starter feed (PS; mean particle size = 4.53 mm in diameter) and (iv) ground starter feed with chopped alfalfa hay (GS + AH; mean particle size = 1.02 mm in diameter). The calves fed GS + AH diets had greater (p < 0.01) starter intake, final body weight and average daily gain compared with the other groups, while GS and TS groups both had greater (p < 0.01) starter intake than the PS group. Feed efficiency was found to be better (p < 0.05) in the TS group than in the GS or PS group, but not different from the GS + AH one. Compared with the other groups, the GS + AH group had the highest (p < 0.01), while the PS one had the lowest (p < 0.01) concentrations of blood glucose and triglyceride. The calves fed GS + AH had the highest blood concentrations of total protein, globulin, triiodothyronine (T3), thyroxin (T4), T3 : T4 ratio (p < 0.05) and levels of fat and glycogen in the liver (p < 0.01) compared with the other groups. The highest (p < 0.05) liver glycogen contents were observed in the GS + AH and TS groups. The duodenum, ileum and jejunum in the calves fed GS + AH exhibited a greater muscle layer thickness (p < 0.05) compared with the other groups. Based on the results obtained, the addition of dietary forage to starter diets positively influenced performance, liver composition and intestinal morphology in developing calves. 相似文献
49.
Muhammad Saeed Daryoush Babazadeh Muhammad Naveed Muhammad Asif Arain Faiz Ul Hassan Sun Chao 《Tropical animal health and production》2017,49(7):1329-1338
Betaine is found ubiquitously in plants, animals, microorganisms, and rich dietary sources including seafood, spinach, and wheat bran. The chief physiological role of betaine is to function as a methyl donor and an osmolyte. Betaine also acts as an osmolyte, to maintain the avian’s cellular water and ion balance to improve the avian’s capacity against heat stress via preventing dehydration and osmotic inactivation. It helps in maintaining the protective osmolytic activity, especially in heat-stressed birds. Betaine may promote various intestinal microbes against osmotic variations and thus improve microbial fermentation activity. Previous studies showed that dietary supplementation of betaine in poultry diets could positively affect nutrients’ digestibility, reduce abdominal fat weight, and increase breast meat yield. In addition, betaine has been reported to protect internal organs and boost their performance. Its inclusion in poultry diet is sparing essential amino acids like choline and methionine. In addition, it may play an important role in lean meat production by positively affecting the lipid metabolism with increased fatty acids catabolism and thus reducing carcass fat deposition. The aim of this review article was to broaden the knowledge regarding betaine and its importance in the poultry industry to cope with the heat stress problem. Moreover, it should be added to the diet as a natural anti-stressor through different routes (water/feed) to overcome the heat stress problem. However, further studies need to be conducted at the genetic and molecular basis to elucidate the mechanism behind the betaine as a natural anti-heat agent to decrease the heat stress problem in the poultry industry. 相似文献