全文获取类型
收费全文 | 1101篇 |
免费 | 64篇 |
国内免费 | 9篇 |
专业分类
林业 | 67篇 |
农学 | 72篇 |
基础科学 | 27篇 |
412篇 | |
综合类 | 104篇 |
农作物 | 104篇 |
水产渔业 | 67篇 |
畜牧兽医 | 190篇 |
园艺 | 29篇 |
植物保护 | 102篇 |
出版年
2023年 | 16篇 |
2022年 | 50篇 |
2021年 | 73篇 |
2020年 | 71篇 |
2019年 | 94篇 |
2018年 | 115篇 |
2017年 | 105篇 |
2016年 | 78篇 |
2015年 | 38篇 |
2014年 | 45篇 |
2013年 | 131篇 |
2012年 | 57篇 |
2011年 | 71篇 |
2010年 | 41篇 |
2009年 | 29篇 |
2008年 | 37篇 |
2007年 | 26篇 |
2006年 | 26篇 |
2005年 | 12篇 |
2004年 | 6篇 |
2003年 | 7篇 |
2002年 | 5篇 |
2000年 | 4篇 |
1999年 | 1篇 |
1998年 | 4篇 |
1997年 | 4篇 |
1996年 | 4篇 |
1994年 | 3篇 |
1993年 | 3篇 |
1992年 | 1篇 |
1991年 | 3篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1972年 | 1篇 |
排序方式: 共有1174条查询结果,搜索用时 31 毫秒
991.
Dietary forage concentration and particle size affect sorting,feeding behaviour,intake and growth of Chinese holstein male calves 下载免费PDF全文
A. U. R. Muhammad C. Q. Xia B. H. Cao 《Journal of animal physiology and animal nutrition》2016,100(2):217-223
The objective of study was to evaluate the effect of forage concentration (F:C) and forage particle length (FPL) on sorting, feeding behaviour, intake, growth and body measurements of growing calves. Twenty‐eight weaned calves of body weight 156.79 ± 33.44 (mean ± SD) were used in 2 × 2 factorial arrangements with the factors FPL of hay grass (full and short) and hay grass concentrations (low, 50% and high, 65%). The treatments were as follows: full length (FL) with low F:C (50:50), FL with high F:C(65:35), short length (SL) with low F:C (50:50) and SL with high F:C (65:35). Increasing F:C and decreasing FPL enhanced sorting for short and fine particle and sorting against long particle (p < 0.05). Dry matter intake (DMI) was decreased by decreasing the FPL (p < 0.05). Increasing F:C (65:35) increased the DMI (p < 0.05). A positive interaction between FPL and F:C was found for (daily weight gain) DWG, weight gain (WG) and feed conversation ratio (FCR) (p < 0.05). In case of feeding behaviour, interaction for eating time and eating time per kilogram DM was present. Increasing the F:C increased the eating time in both FL and SL (p < 0.05). Chopping of hay had decreased the chewing time (p < 0.05). Increasing F:C increased chewing time per kilogram DMI. High F:C decreased the lying time (p < 0.05) in FL and SL treatments (p < 0.05). Increasing F:C reduced the overall abnormal behaviour (p < 0.05). These results suggested that animals performed better at higher F:C at SL diet. Intensity of sorting for short and fine particle and against long particle increased at higher F:C and SL diets. Eating time and eating time per kilogram DMI increased by increasing F:C level in both FL and SL treatments. Chewing time increased by increasing the FPL, while increasing the F:C enhanced the chewing time per kilogram DMI and reduced animal's abnormal behaviour. 相似文献
992.
993.
Muhammad A. I. Dalia A. M. Loh T. C. Akit H. Samsudin Anjas A. 《Veterinary research communications》2022,46(2):431-445
Veterinary Research Communications - This study compares the effects of sodium selenite, selenium yeast, and enriched bacterial organic selenium protein on antioxidant enzyme activity, serum... 相似文献
994.
Khurshaid Khan Nazma Habib Khan Farhat Anwar Ihtisham Ullah Noor Badshah Irfan Irfan Khalid Iqbal Ibrar Shah Shah Tariq Aziz Muhammad Shahid Naseem Khan Safeer Ullah Shah 《Zoonoses and public health》2022,69(1):33-45
Present study was carried to determine the sand fly species composition, breeding sites ecology, seasonal abundance, and spatial distribution in district Malakand, Khyber Pakhtunkhwa, Pakistan. In addition, risk factors associated with cutaneous leishmaniasis (CL) were also evaluated. Survey of indoor and outdoor habitats was carried out using sticky traps in 31 villages of Dargai and Batkhela tehsils of Malakand. Soil from habitats of adult and immature sand flies was analysed. Questionnaire-based household survey was also performed in these villages to assess risk factors associated with CL. Soil samples from selected CL positive households were analysed for its contents. Additionally, clinicoepidemiological data from local health centres was examined for the year 2019. Total of 3,140 sand flies belonging to 18 species were collected. Phlebotomus sergenti was the most abundant species (38.16%). Its abundance had a strong positive correlation with mean monthly relative humidity and negative correlation with average temperature. Phlebotomus sergenti and Phlebotomus papatasi were abundant at an elevation ranging from 320 to 1,120 m above sea level and in agricultural lands near human settlements. Flight height preference apparatus collected maximum sand flies at 30 cm (1ft) above the ground and all species associated negatively with height. Soil analysis from habitats of adult and immature flies showed that highest mean number of adults and immatures were recorded from silt loam which carried highest concentrations of K2O, Mg, Ca, and Zn. Number of immature sand flies correlated moderately (r = .7, p < .05) with K2O soil concentrations. There was significant similarity between organic matter contents in soil samples from positive breeding sites and CL households (Wilcoxon rank-sum test, p = .1976). In multivariate analysis model for CL risk factors, age (26–35 and >35 years), knowledge of leishmaniasis, living in a middle and upper class, preachers visit to villages, and assumption that Afghan refugees are more prone to CL were significant. CL patient's archived data from health centres showed that majority of patients had lesions on face and hands. Patient's influx was highest in February and March. 相似文献
995.
Farm Level Tree Planting in Pakistan: The Role of Farmers’ Perceptions and Attitudes 总被引:1,自引:0,他引:1
The low proportion of forested land and continuing degradation of existing forest cover are serious threats to the sustainability
of forestry in Pakistan. Farm forestry has been identified as a feasible solution, particularly in the plain areas. Applying
the Theory of Planned Behaviour in a survey of 124 farmers in Dera Ismail Khan district of Pakistan’s North West Frontier
Province showed that farmers’ willingness to grow trees on their farms is a function of their attitudes towards the advantages
and disadvantages of growing trees, their perception of the opinions of salient referents and factors that encourage and discourage
farm level tree planting. Farmers viewed farm forestry as economically beneficial and environmentally friendly. Tree planting
was perceived as increasing income, providing wood for fuel and furniture, controlling erosion and pollution and providing
shade for humans and animals. Farmers saw hindrance in agricultural operations and the harbouring of insects, pests and diseases
as negative impacts of tree planting; however, these were outweighed by their perceptions of positive impacts. Tree growing
decisions of farmers were influenced by the opinions of family members, owners/tenants, fellow farmers and village elders.
The factors that significantly predicted farm level tree planting were availability of barren land, lack of markets, lack
of nurseries and damage caused by animals and humans. Farm forestry programmes are more likely to be successful if they acknowledge
and address the factors which underlie farmers’ reasons for planting or not planting trees. 相似文献
996.
Asma Hassan Shahzada Sohail Ijaz Rattan Lal Safdar Ali Qaiser Hussain Muhammad Ansar Romaan Hayat Khattak Muhammad Sharif Baloch 《Land Degradation \u0026amp; Development》2016,27(4):1175-1185
Depth distribution of soil organic carbon (SOC) fractions depends on the efficiency of agro‐technical managements. Information on depth distribution of SOC fractions mostly confined to the plow layer and scant in dry lands of Punjab, Pakistan. Therefore, a field experiment was laid out with moldboard plow (MP) (control), tine cultivator (TC), and minimum tillage (MT) as main plots, and cropping sequences fallow wheat (Triticum aestivum L.), (FW, control), mungbean (Vigna radiata L.) wheat (MW), sorghum (Sorghum bicolor L.) wheat (SW), green manure wheat (GW), and mungbean‐chickpea (MC) (Cicer arietinum L.) as sub‐plots. Treatment effects were assessed for microbial biomass carbon (MBC), potentially mineralizeable carbon (PMC), particulate organic carbon (POC), dissolved organic carbon (DOC), HCl insoluble carbon (HIC), and stratification ratio (SR) in Rawal series: Udic Haplustalf. Alfisols. The MBC concentration was the highest in MT system, at 15 to 30‐cm depth under MW and PMC concentration was highest under SW with MT at 45–60 cm. MP had higher POC in FW sequence. The highest DOC was at 0 to 15‐cm depth under MC with TC and stock of HIC was more under TC with FW sequence. The highest SR of PMC was under MT with FW at 0–15:15–30 and POC was under TC and MP with FW at depths of 0–15:45–60 cm. The highest SR for DOC was under MP with GW at 0–15:45–60 cm and HCl insoluble C was under MT with SW at 0–15:45–60. In broad‐spectrum, labile organic fractions revealed differential sensitivity, and POC stocks are also a sensitive indicator to detect the short‐management effects. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
997.
A statistical algorithm for comparing mode shapes of vibration testing before and after damage in timbers 总被引:3,自引:0,他引:3
Instances of local damage in timber such as knots, decay, and cracks can be translated into a reduction of service life due
to mechanical and environmental loadings. In wood construction, it is very important to evaluate the weakest location and
to detect damage at the earliest possible stage to avoid future catastrophic failure. In this study, modal testing was used
on wood beams to generate the first two mode shapes. A novel statistical algorithm was proposed to extract a damage indicator
by computing mode shapes of vibration testing before and after damage in timbers. The different damage severities, damage
locations, and damage counts were simulated by removing mass from intact beams to verify the algorithm. The results showed
that the proposed statistical algorithm is effective and suitable for the designed damage scenarios. It is reliable for the
detection and location of local damage of different severities, location, and number. The peak values of the damage indicators
computed from the first two mode shapes were sensitive to different damage severities and locations. They were also reliable
for the detection of multiple cases of damage. 相似文献
998.
999.
1000.
A 92 d greenhouse pot experiment with maize (Zea mays L.) was carried out with a strongly saline soil from Pakistan (P‐s) in comparison with a nonsaline soil from Germany (G‐s) similar in pH and texture. The aim was to evaluate salinity effects on the decomposition of compost and effects of compost and P amendments on (1) plant growth and (2) microbial‐biomass formation. The yield of maize shoot‐C and root‐C increased in both soils in the order nonamended control < +triple superphosphate (TSP) (A1) < +compost (A2) < +(compost + TSP) (A3) < +TSP‐enriched compost (A4). In comparison with the control, the highest yield in treatment A4 was nearly doubled on the G‐s, but was increased more than 8‐fold on the saline P‐s. Averaging the three compost treatments, 32% of the compost added was decomposed in the German soil and 36% in the Pakistani soil on the basis of the compost recovered as particulate organic matter. These data were roughly in agreement with the CO2‐evolution data. This indicates that the decomposition of compost was not affected by salinity. Compost‐derived CO2 was mainly evolved until day 32, the root‐derived CO2 from day 74 until the end of the experiment. The addition of compost resulted in higher contents of microbial biomass C and biomass P, but also in that of NaHCO3‐extractable P. These three properties were significantly interrelated (r = 0.64–0.85), but on a lower level of significance than the relationships between shoot‐C, root‐C, and NaHCO3‐extractable P (r = 0.90–0.93). Applying compost enriched with TSP (incubation of compost and TSP for 24 h) provided considerably more P to plants and microorganisms than the separate addition of these two components. The results suggest that the role of the microbial biomass as a sink and source for available P deserves further attention. 相似文献