全文获取类型
收费全文 | 312篇 |
免费 | 18篇 |
专业分类
林业 | 18篇 |
农学 | 15篇 |
基础科学 | 3篇 |
73篇 | |
综合类 | 7篇 |
农作物 | 59篇 |
水产渔业 | 50篇 |
畜牧兽医 | 78篇 |
园艺 | 12篇 |
植物保护 | 15篇 |
出版年
2023年 | 2篇 |
2022年 | 10篇 |
2021年 | 18篇 |
2020年 | 19篇 |
2019年 | 23篇 |
2018年 | 19篇 |
2017年 | 27篇 |
2016年 | 20篇 |
2015年 | 13篇 |
2014年 | 13篇 |
2013年 | 36篇 |
2012年 | 21篇 |
2011年 | 30篇 |
2010年 | 10篇 |
2009年 | 12篇 |
2008年 | 15篇 |
2007年 | 8篇 |
2006年 | 7篇 |
2005年 | 7篇 |
2004年 | 5篇 |
2003年 | 3篇 |
2002年 | 2篇 |
2000年 | 1篇 |
1999年 | 1篇 |
1995年 | 1篇 |
1994年 | 3篇 |
1989年 | 2篇 |
1987年 | 1篇 |
1945年 | 1篇 |
排序方式: 共有330条查询结果,搜索用时 46 毫秒
201.
Amin Tamadon Mojtaba Kafi Mehdi Saeb Abdolah Mirzaei Saedeh Saeb 《Tropical animal health and production》2011,43(1):29-34
The relations between body condition score (BCS), milk yield, serum insulin-like growth factor-I (IGF-I) profile, and luteal
activity were investigated in postpartum dairy cows. Seventy-one healthy high-producing multiparous Holstein cows were subjected
to transrectal ultrasound scanning twice weekly from the first to the eighth week postpartum. Blood samples were collected
twice weekly to measure serum progesterone (P4) and every 2 weeks to detect serum IGF-I concentrations. BCS was monitored
weekly after calving. Cows with serum P4 concentrations ≥1 ng/ml on at least two consecutive samplings were considered to
have commenced luteal activity. Commencement of luteal activity (C-LA) was observed earlier than 45 days postpartum in 71.8%
of cows while 28.2% showed C-LA later than 45 days. Prolonged luteal phase was the most common abnormal pattern of luteal
activity observed. Cows with a C-LA earlier than 45 days postpartum had higher (P ≤ 0.05) mean serum concentrations of IGF-I than those with later C-LA. In addition, cows which showed C-LA earlier than 45 days
postpartum had more optimal productive indices including shorter calving to conception interval and calving to first service
interval (P ≤ 0.05), and fewer services per conception (P = 0.07). C-LA was significantly later in cows that lost more than 0.5 BCS units within 3 weeks postpartum than in those that
lost less than 0.5 units BCS during the same interval (P = 0.02). We conclude that high-producing dairy cows with higher postpartum serum IGF-I concentrations have earlier commencement
and normal luteal activity, and better reproductive performance. Severity and duration of BCS loss adversely affect commencement
of luteal activity. 相似文献
202.
203.
Mehdi Azadvar Virendra Kumar Baranwal D. K. Yadava 《Journal of General Plant Pathology》2011,77(3):194-200
Phyllody disease associated with 16SrIX phytoplasma was observed in the range of 4.1–11% in 10 different lines of toria [Brassica rapa L. subsp. dichotoma (Roxb.)] in experimental fields of the Indian Agricultural Research Institute, New Delhi, India during 2008 and 2009. The
toria phyllody (TP) phytoplasma was detected in all the symptomatic and 13.3% of asymptomatic toria plants by nested PCR.
The phytoplasma was detected in midrib, flower part, siliquae, stem, and root of infected plants as well as seeds. TP was
transmitted by grafting and by dodder to toria and nine other rapeseed/mustard species as confirmed by nested PCR. However,
symptoms of phytoplasma infection were induced only in toria, yellow sarson [Brassica
rapa L. subsp. trilocularis (Roxb.)], brown sarson [Brassica
rapa L. subsp. sarson (Prain)], rapeseed (B. napus subsp. oleifera), and rocket or taramira (Eruca sativa) but not in mustard (B. juncea), black mustard (B. nigra), Ethiopian mustard (B. carinata), B. tournefortii and white mustard (Sinapis alba). Transmission of TP phytoplasma to periwinkle (Catharanthus roseus) was successful only through dodder, but no transmission to tomato (Lycopersicon esculentum) or brinjal (Solanum melongena) was found. TP phytoplasma was detected in Laodelpax striatellus, an abundant planthopper in toria fields, which indicates that this planthopper may be a potential vector for TP phytoplasma. 相似文献
204.
Saeed Keyvanshokooh Ahmad Ghasemi Mohsen Shahriari-Moghadam Rajab Mohammad Nazari & Mehdi Rahimpour 《Aquaculture Research》2007,38(9):953-956
The Caspian roach (Rutilus rutilus caspicus) is regarded as one of the most important commercial species in the Caspian Sea. Despite the commercial and conservation importance of the species, information on genetic relationships and diversities at the molecular level in Rutilus rutilus caspicus is scarce. Six microsatellite loci were analysed to study the genetic variation in two major populations of Caspian roach in the Iranian waters of the Caspian Sea: the Anzali Wetland and Gorgan Bay. The Fst value between populations was 0.07, suggesting that the genetic differentiation was significant (P<0.01). Both the studied populations deviated from Hardy–Weinberg equilibrium proportions at a number of loci, mostly due to the deficiency of heterozygosities. The genetic distance between populations was 0.29, which indicates that the genetic difference among the studied populations is pronounced. The differences between both populations were not statistically significant (P>0.05), neither for average number of alleles per locus nor for observed heterozygosities. The data generated in this study provide useful information on the genetic variation and differentiation in populations of Caspian roach. 相似文献
205.
206.
Bending moment resistance of dowel corner joints in case-type furniture under diagonal compression load 总被引:1,自引:0,他引:1
We investigated bending moment resistance under diagonal compression load of corner doweled joints with plywood members. Joint members were made of 11-ply hardwood plywood of 19 mm thickness. Dowels were fabricated of Beech and Hornbeam species. Their diameters(6, 8 and 10 mm) and depths of penetration(9, 13 and 17 mm) in joint members were chosen variables in our experiment. By increasing the connector's diameter from 6 to 8 mm, the bending moment resistance under diagonal compressive load was increased, while it decreased when the diameter was increased from 8 to 10 mm. The bending moment resistance under diagonal compressive load was increased by increasing the dowel's depth of penetration. Joints made with dowels of Beech had higher resistance than dowels of Hornbeam. Highest resisting moment(45.18 N·m) was recorded for joints assembled with 8 mm Beech dowels penetrating 17 mm into joint members Lowest resisting moment(13.35 N·m) was recorded for joints assembled with 6 mm Hornbeam dowels and penetrating 9 mm into joint members. 相似文献
207.
Hamidreza Edalat Mehdi Faezipour Volker Thole Frederick A. Kamke 《Wood Science and Technology》2014,48(4):703-712
The importance of adhesion in production of wood-based composites is well-known. Adhesive penetration and interphase morphology play an important role in bond strength and product performance. Many studies offered different methods for interphase characterization and analysis. Both qualitative and quantitative methods have been used to analyze the bondline. Most of the quantitative methods were developed for bonded assemblies of veneer or wood blocks. Adhesive penetration measurement in particulate wood-based composites is the main scope of this study. For this purpose, uniform oriented strand board with veneer strands was produced by the use of phenol formaldehyde resin with 2, 6, and 10 % strand moisture content (MC). The strands were formed into well-organized mats to achieve a uniform structure for the composite. Cross-section specimens were prepared from each board and observed by epifluorescence microscopy. Six positions for growth-ring angle in adhesive joints were denoted to evaluate penetration in different directions of the wood. Four parameters were also determined to quantify resin penetration patterns by counting the quantity of the main anatomical elements of wood, which were filled with resin. Finally, it was determined that this method could recognize the differences between adhesive penetration in boards produced with different level of strand MC. Resin penetration in strands with 6 and 10 % MC was the greatest. Growth-ring angle of the strands influenced penetration as it was increased when both strands meet each other in an oblique position, although this effect was significant only in maximum penetration depth in fibers. 相似文献
208.
Majid Talebi Zahra Hajiahmadi Mehdi Rahimmalek 《Journal of Crop Science and Biotechnology》2011,14(3):173-178
In the present study, genetic diversity of 48 individual plants from four Iranian cultivated populations of alfalfa (Medicago sativa L.) was evaluated using sequence-related amplified polymorphism (SRAP) markers. Fourteen SRAP primer combinations produced
193 fragments of which 95 were polymorphic. The number of polymorphic fragments detected per primer combination ranged from
3 to 10 bands with an average of 6.78 bands. Average polymorphic information content (PIC) was 0.343 for all primer combinations.
Although the AMOVA (analysis of molecular variance) results showed a significant difference in the genetic diversity among
the populations (P < 0.0001), the genetic variation mainly caused by the variation of intra population accounted for 93.17%
of the total genetic variation. Unweighted pair-group method arithmetic average (UPGMA) analysis of the marker data clearly
separated the populations of subtropical (Yazdi) and semi-cold (Hamadani and Nikshahri) as well as Kodi, an improved population.
It can be concluded that SRAP markers are useful for studying diversity and relationships among and within alfalfa populations. 相似文献
209.
Rahimi Ataollah Mirmoayedi Alinaghi Kahrizi Danial Zarei Leila Jamali Samad 《植物病害和植物保护杂志》2022,129(6):1331-1342
Journal of Plant Diseases and Protection - The honey bee (Apis mellifera), as one of the most important pollinating insects, plays a critical role in biodiversity conservation and global food... 相似文献
210.
Tahere Doavi Seyed Latif Mousavi Mehdi Kamali Jafar Amani Mahdi Fasihi Ramandi 《Iranian Biomedical Journal》2016,20(2):97-108