全文获取类型
收费全文 | 341篇 |
免费 | 25篇 |
专业分类
林业 | 12篇 |
农学 | 13篇 |
基础科学 | 7篇 |
102篇 | |
综合类 | 6篇 |
农作物 | 84篇 |
水产渔业 | 57篇 |
畜牧兽医 | 53篇 |
园艺 | 8篇 |
植物保护 | 24篇 |
出版年
2023年 | 4篇 |
2022年 | 13篇 |
2021年 | 10篇 |
2020年 | 14篇 |
2019年 | 24篇 |
2018年 | 26篇 |
2017年 | 48篇 |
2016年 | 37篇 |
2015年 | 15篇 |
2014年 | 20篇 |
2013年 | 36篇 |
2012年 | 21篇 |
2011年 | 36篇 |
2010年 | 24篇 |
2009年 | 1篇 |
2008年 | 14篇 |
2007年 | 10篇 |
2006年 | 9篇 |
2005年 | 1篇 |
2004年 | 3篇 |
排序方式: 共有366条查询结果,搜索用时 15 毫秒
21.
22.
Shamsuddin M Goodger WJ Hossein MS Azizunnesa Bennett T Nordlund K 《Tropical animal health and production》2006,38(2):131-140
Identified economic opportunities for planning interventions greatly increase farmers’ compliance with an extension programme.
We investigated opportunities for interventions to increase dairy farmers’ income in four areas of Bangladesh, including the
districts of Mymensingh, Khulna-Satkhira, Sirajgonj-Pabna and Chittagong. The data were collected from 1440 dairy farms at
a one-day visit and were summarized as the difference between management targets and each herd’s calculated management indices.
The average number of lactating cows, feed cost as a percentage of income from milk, milk sold as percentage of milk produced,
lactating cows as a percentage of mature cows, and lactating cows as a percentage of total cattle varied from 1.5 to 3.4,
from 52.5% to 92.1%, from 78.7% to 92.6%, from 81.9% to 86.7% and from 34.3% to 37.7%, respectively. The average age at first
calving, calf production interval, lactation length, and milk production were 35.0–44.3 months, 14.0–17.6 months, 249–286
days and 3.5–7.2 litres, respectively, depending on the locality. The average cost for producing 100 litres of milk was 18.9–35.1
US dollars. The production cost increased when daily milk production per cow decreased (r2 = 0.43–0.55). Management improvements directed towards increasing average milk production per cow per day, increasing lactation
length, decreasing age to first calving, and decreasing calf production interval could expect to yield an average income increase
up to a range of 676.3–1730.6 US dollars depending on the milk-producing area. 相似文献
23.
24.
Hossein Mohammadi Mohammad Moradi Shahrebabak Mahmood Vatankhah Hossein Moradi Shahrebabak 《Tropical animal health and production》2012,45(1):185-191
Genetic parameters and genetic trends for birth weight (BW), weaning weight (WW), 6-month weight (6MW), and yearling weight (YW) traits were estimated by using records of 5,634 Makooei lambs, descendants of 289 sires and 1,726 dams, born between 1996 and 2009 at the Makooei sheep breeding station, West Azerbaijan, Iran. The (co)variance components were estimated with different animal models using a restricted maximum likelihood procedure and the most appropriate model for each trait was determined by Akaike’s Information Criterion. Breeding values of animals were predicted with best linear unbiased prediction methodology under multi-trait animal models and genetic trends were estimated by regression mean breeding values on birth year. The most appropriate model for BW was a model including direct and maternal genetic effects, regardless of their covariance. The model for WW and 6MW included direct additive genetic effects. The model for YW included direct genetic effects only. Direct heritabilities based on the best model were estimated 0.15?±?0.04, 0.16?±?0.03, 0.21?±?0.04, and 0.22?±?0.06 for BW, WW, 6MW, and YW, respectively, and maternal heritability obtained 0.08?±?0.02 for BW. Genetic correlations among the traits were positive and varied from 0.28 for BW–YW to 0.66 for BW–WW and phenotypic correlations were generally lower than the genetic correlations. Genetic trends were 8.1?±?2, 67.4?±?5, 38.7?±?4, and 47.6?±?6 g per year for BW, WW, 6MW, and YW, respectively. 相似文献
25.
The current study was designed to evaluate therapeutic potential of systemically administered ethanolic and aqueous extracts of saffron as well as its bioactive ingredients, safranal and crocin, in chronic constriction injury (CCI)-induced neuropathic pain in rats. The von Frey filaments, acetone drop, and radiant heat test were performed to assess the degree of mechanical allodynia, thermal allodynia and thermal hyperalgesia respectively, at different time intervals, i.e., one day before surgery and 3, 5, 7 and 10 days post surgery. The ambulatory behavior was evaluated using the open field test. A 7-day treatment with the ethanolic and aqueous extracts (50,100 and 200 mg/kg, i.p.) and safranal (0.025, 0.05 and 0.1 mg/kg, i.p.), attenuated the behavioral symptoms of neuropathic pain in a dose dependent manner. Crocin even at the high dose (50 mg/kg) failed to produce any protective role. However, gabapentine (100 mg/kg) as a reference drug significantly alleviated all behavioral manifestations of neuropathic pain compared to control group. In conclusion, the results of this study suggest that ethanolic and aqueous extracts of saffron as well as safranal could be useful in treatment of different kinds of neuropathic pains and as an adjuvant to conventional medicines. 相似文献
26.
Nikbakht G Rezaii H Stear MJ Talebi MA Mahmoudzadeh H 《Veterinary journal (London, England : 1997)》2012,192(3):547-549
Ovar-DRB1 is one of the most important response genes in the major histocompatibility complex (MHC) class II region of sheep. Gene polymorphism in the second exon of Ovar-DRB1 in three different Iranian fat-tailed sheep breeds (Lori-Bakhtiari, Shaul and Zandi) was analyzed by either restriction fragment length polymorphisms (RFLP) or direct sequencing. A total of 92 Lori-Bakhtiari, 40 Shaul, and 47 Zandi sheep were examined. PCR-RFLP identified 17 genotypes in Lori-Bakhtiari sheep, 12 in Shaul sheep and 11 in Zandi sheep. Collectively, 24 different genotypes could be found for Iranian fat-tailed sheep. Using direct sequencing, seven new sequences in exon 2 of the Ovar-DRB1 gene were identified. Generalized linear modeling with a multinomial error structure showed that the sheep populations had significantly different allele frequencies. 相似文献
27.
Arash Omidi Hossein Ansari nik Mahmood Ghazaghi 《Tropical animal health and production》2013,45(2):431-434
Ten blue-neck male ostriches (Struthio camelus) were fed Prosopis farcta beans throughout a 30-day experiment. Blood samples were collected from ostriches on days 0 and 30 to measure levels of high-density lipoprotein (HDL) cholesterol, low-density lipoprotein (LDL) cholesterol, triglyceride, total serum protein, albumin, globulin, cholesterol, calcium, inorganic phosphorus, the activity of aspartate aminotransferase, alanine aminotransferase, and γ-glutamyl transferase (γ-GT). From days 0 to 30, HDL cholesterol, total protein, and globulins levels increased significantly whereas LDL cholesterol, inorganic phosphorus, and γ-GT activity decreased significantly. 相似文献
28.
Identification of genetic factors controlling traits associated with seed germination under drought stress conditions, leads to identification and development of drought tolerant varieties. Present study by using a population of F2:, derived from a cross between a drought tolerant variety, Gharib (indica) and a drought sensitive variety, Sepidroud (indica), is to identify and compare QTLs associated with germination traits under drought stress and non-stress conditions. Through QTL analysis, using composite interval mapping, regarding traits such as germination rate (GR), germination percentage (GP), radicle length (RL), plumule length (PL), coleorhiza length (COL) and coleoptile length (CL), totally 13 QTLs were detected under pole drought stress (-8 MPa poly ethylene glycol 6000) and 9 QTLs under non-stress conditions. Of the QTLs identified under non-stress conditions, QTLs associated with COL (qCOL-5) and GR (qGR-1) explained 21.28% and 19.73% of the total phenotypic variations, respectively Under drought stress conditions, QTLs associated with COL (qCOL-3) and PL (qPL-5) explained 18.34% and 18.22% of the total phenotypic variations, respectively. A few drought-tolerance-related QTLs identified in previous studies are near the QTLs detected in this study, and several QTLs in this study are novel alleles. The major QTLs like qGR-1, qGP-4, qRL-12 and qCL-4 identified in both conditions for traits GR, GP, RL and CL, respectively, should be considered as the important and stable trait-controlling QTLs in rice seed germination. Those major or minor QTLs could be used to significantly improve drought tolerance by marker-assisted selection in rice. 相似文献
29.
In this research experiment, two commercial onion cultivars (Allium cepa L., cvs. Dorrcheh and Cebolla Valenciana) were grown in sand culture and exposed to two levels of selenium (Se) (0 and 25?µM) and two levels of sulfate (1 and 3?mM). According to the results obtained, addition of 25?µM Se in combination with 3?mM sulfate was not only effective in significant increase of onion bulb yield, but it significantly increased Se concentration of bulb. By considering the average consumption of onion in central Iran, the daily intake of Se via consumption of Se-biofortified onion is estimated to be 68.4–77.2?µg in spring and summer and 72.6–117.1?µg in fall and winter. These amounts of daily intakes of Se is higher than the sufficient levels of Se recommended by world health organization (WHO) but less than the maximum tolerable level of Se (400?µg Se per day) for human. 相似文献
30.
OBJECTIVE: To assess the effects of socio-economic status (SES) on BMI, waist:hip ratio (WHR) and waist circumference (WC) in a group of Iranian women. METHODS: A cross-sectional study was conducted on 888 women in Sistan and Baluchestan Province. SES was measured using level of education. In addition, parity, marital status and physical activity were assessed. Standardized measurements were taken, BMI and WHR were calculated. RESULTS: Low education level was a strong determinant of overweight and obesity among Iranian women. After controlling for age, women with higher education level had significantly lower BMI, WC and parity. Multiple linear regression analysis found a significant negative association of BMI and WC with education level and a significant positive association of BMI and WC with parity. Significant factors associated with obesity by a logistic regression model were education level (OR for university graduates v. illiterate or low literacy levels: 1.00 v. 3.70; P = 0.01), living with spouse (OR for married v. single subjects: 1.00 v. 0.15; P = 0.05), parity (OR for more than five v. less than two pregnancies: 1.00 v. 0.34; P = 0.03) and WC (OR for < 0.88 cm v. > or = 0.88 cm: 1.00 v. 11.20; P = 0.001). CONCLUSION: The present study revealed that educational level, multiple pregnancies, marital status and lack of exercise are some possible explanations for the obesity among Sistan and Baluchestan women. 相似文献