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   202篇
  免费   8篇
  国内免费   1篇
林业   3篇
农学   11篇
基础科学   6篇
  83篇
综合类   8篇
农作物   23篇
水产渔业   21篇
畜牧兽医   42篇
园艺   3篇
植物保护   11篇
  2023年   2篇
  2021年   10篇
  2020年   10篇
  2019年   16篇
  2018年   28篇
  2017年   17篇
  2016年   11篇
  2015年   4篇
  2014年   3篇
  2013年   18篇
  2012年   11篇
  2011年   11篇
  2010年   13篇
  2009年   6篇
  2008年   12篇
  2007年   9篇
  2006年   7篇
  2005年   2篇
  2004年   1篇
  2003年   5篇
  2002年   4篇
  2001年   1篇
  2000年   1篇
  1999年   1篇
  1998年   1篇
  1996年   1篇
  1994年   1篇
  1990年   1篇
  1989年   1篇
  1987年   2篇
  1977年   1篇
排序方式: 共有211条查询结果,搜索用时 15 毫秒
1.
2.
Theileria equi (T. equi) is an obligate intra- and extra-erythrocytic parasite that causes equine theileriosis (ET) in equids. Equine theileriosis is considered a notifiable disease of global significance, a major constraint to the international movement of horses, and endemic in many countries. This disease may be difficult to diagnose, as it can produce variable and nonspecific clinical signs. A cross-sectional study was designed for the molecular characterisation of T. equi and to investigate the associated risk factors of ET accompanied by its consequences on haematological and sero-biochemical parameters. A convenience sampling of 500 blood samples were collected from ET suspect horses from January to December 2017. PCR was performed on all blood samples targeting the 18S rRNA gene of T. equi followed by sequencing; 9% animals tested positive with confirmed sequences. The isolates of this study showed high homology with Cuban, Russian and Brazilian isolates of T. equi (accession numbers KY111762.2 , MG551915.1 and KY952237.1 , respectively). Based on multivariate analysis, the principal risk factors consisted of absence of dogs on the premises and presence of tick infestation. The haemato-biochemical parameters showed a decrease in granulocytes and erythrocytes, and an increase in lymphocytes, monocytes, mean corpuscular volume, mean corpuscular haemoglobin, mean platelet volume, glucose, phosphorus and aspartate aminotransferase in positive horses. This is the first study which identified ET in Punjab (Pakistan) using molecular techniques and risk factors together with the haemato-biochemical variations in horses.  相似文献   
3.
An experiment was conducted for 60 d in a recirculatory system consisting of 20 glass aquariums (each of size 41 × 41 × 46 cm) to evaluate meat and bone meal (MBM) as partial replacement for fish meal (FM) in Macrobrachium rosenbergii postlarvae (PLs) with a view to develop an inexpensive nursery diet. Three nursery diets were formulated to contain 32% protein and to be as isoenergetic as possible. FM in these diets was progressively replaced with MBM (Diet 1 contained 25% FM and 14% MBM, Diet 2 contained 20% FM and 20% MBM, and Diet 3 contained 15% FM and 26% MBM). Inclusion levels of mustard oilcake and sesame meal in diets were kept fixed at 10%. A commercial shrimp nursery diet (30% protein) from Saudi Bangla Fish Feed Ltd., Mymensingh, was used as the reference diet (Diet 4). Each treatment had three replicates. PLs of M. rosenbergii (26 ± 0.02 mg) were stocked at the rate of 60 PLs (1 PL/L) in each aquarium. At the beginning, PLs were fed three times daily at a rate of 20% of the body weight and it was gradually reduced to 10% at Day 30. The ranges of water quality parameters in the system were as follows: temperature, 27–29 C; dissolved oxygen, 6.5–8.4 mg/L; pH, 6.8–8.3; and total ammonia, 0.01–0.15 mg/L. The result of the study showed that there was no significant difference (P > 0.05) between the weight gains of PLs fed Diet 1 (containing 14% MBM) and Diet 4 (reference diet) but was significantly higher than other dietary groups containing higher levels of MBM. Diets 1 and 4 showed significantly lower (P < 0.05) apparent food conversion ratios (1.74 and 1.73, respectively). The survival (%) of PLs ranged between 62 and 76% with PLs fed Diets 1 and 4 showing significantly higher (P < 0.05) survival. The result of the study demonstrated that the MBM could be included at 14% level in a nursery diet, and a diet containing 25% FM, 14% MBM, 10% sesame meal, and 10% mustard oilcake may be recommended for profitable production of PLs of M. rosenbergii.  相似文献   
4.
Chemical and spectroscopic characteristics were determined on the organic matter in two Luvisolic soils from northwestern Alberta, Canada. One of these (the Debolt soil) is known to crust only slightly while the other (the Demmitt soil) exhibits severe crusting after heavy rainfalls. The Debolt top soil is richer in total C, total N, carbohydrates and proteinaceous materials than the Demmitt top soil. Humic acid extracted from the Debolt soil is more aliphatic, and contains fewer CO2H groups than does humic acid extracted from the Demmitt soil. The quality of the organic matter appears to play a role in soil crusting.  相似文献   
5.
In new agricultural practices, joint application of water and fertilizer has been become common. Uniform distribution of fertilizer in soil and in plant growth duration is possible by this procedure. The main objective of this study was to investigate furrow fertigation management effects on distribution uniformity and runoff losses of nitrate in a cornfield, and validate a numerical fertigation model. A field experiment was carried out with seed corn at 12 experiments with a complete randomized block design during 2 years. Nitrogen requirement was determined by soil analysis and accomplished in four stages of the growth: before cultivation, in seven leaves, shooting and earring stages which first section (before cultivation) was applied by manual distribution and others by fertigation. Potash and super phosphate fertilizers (based on soil analysis) were sprayed on soil before planting. Water requirement was estimated by using class a evaporation pan multiplied by plant (Kc) and pan coefficients. Nitrogen fertilizer was solved in irrigation water and injected at the last minutes of irrigation. The results showed that fertilizer distribution uniformity of the low quarter (DULQ) ranged from 85.7% to 91.5% in first year, and 69.9% to 95.5% in second year. While water DULQ ranged from 74.1 to 98.2% in 2 years. Nitrate losses of surface runoff have ranged between 5.7 and 42.0% in first year according to the application time and the outflow flux. In second year, the nitrate losses decreased by adopting appropriate management based on the experiences of first year. The fertigation model was subsequently applied to the experimental data and results showed good agreement with field data.  相似文献   
6.
In order to ascertain physico-chemical, functional and geometrical traits of apricot fruit from Northern Areas of Pakistan, six predominantly grown varieties namely, Alman, Habi, Khakhas, Mirmalik, Neeli and Shai were selected in this study. Proximate composition as crude fat (2.1–3%), crude protein (6.18–8.7%), crude fiber (11.85–13.6%), ash (9.45–12.1%) and total sugars (56.8–64.9%) were determined on dry weight basis. The data showed variations among the investigated parameters in all varieties. Functional properties of apricot fruit viz. ascorbic acid (67.39–90.94 mg/100 g), total phenolic compounds (4590–7310 mgGAE/100 g), total carotenoids (10.09–18.13 mg/100 g β-carotene) and antioxidant activity (56.84–82.33%) were also recorded. The data pertaining to mineral contents (mg/100 g) revealed K as the predominant element (2040–3000) followed by P, Mg, Ca, Na and Fe among all the tested samples. Furthermore, geometrical characters of apricot varieties were also determined as important sensory and technological attributes on fresh weight basis. The result from the present study showed that all the tested varieties are highly nutritious and rich in functional components.  相似文献   
7.
Rhizobacteria were isolated from the rhizosphere of different Brassica species and assayed for their ability to produce auxins in vitro. The isolates varied greatly in their potential for auxin production (ranging from 0.33 to 11.40 µg ml-1). L-Tryptophan (an auxin precursor) addition to the media increased the auxin production by several fold. Based upon in vitro auxin production and growth promotion of B. juncea seedlings caused by various isolates under gnotobiotic conditions, promising isolates were selected and tested in pot trial to observe their effects on growth, yield and oil content of the same Brassica species. Results showed that seed inoculation with different isolates of rhizobacteria significantly increased plant height (up to 56.5%), stem diameter (up to 11.0%), number of branches (up to 35.7%), number of pods per plant (up to 26.7%), 1,000-grain weight (up to 33.9%), grain yield (up to 45.4%) and oil content (up to 5.6%) over the uninoculated control. Isolate S54 gave the most promising and consistent results. Highly significant correlations between L-TRP-derived auxin production by plant growth-promoting rhizobacteria (PGPR) in vitro and grain yield (r =0.77**), number of pods (r =0.78**) and number of branches per plant (r =0.77**) of B. juncea were found. It was hypothesized that these PGPR may influence the growth and yield of inoculated plants by production of auxins in the rhizosphere of inoculated plants from the L-TRP present in the root exudates, although other mechanisms of action might have also contributed.  相似文献   
8.
9.
10.
The present investigation reports the novel synthesis of CoWO4 nanoparticles@silk fiber under ultrasound irradiation. The effect of temperature, power of ultrasound irradiation and sequential dipping steps in growth of the CoWO4 particles were studied. Results show a decrease in the particles size as the temperature and power of irradiation decreased. The fibers containing CoWO4 nanoparticles were tested for their antibacterial efficacy against E. coli and S. aureus and were found to possess significant antibacterial activity. The results show the CoWO4 nanoparticles@silk with strongest fluorescence characteristics can be obtained in this method. The physicochemical properties of the nanoparticles were determined by X-ray diffraction (XRD), scanning electron microscopy (SEM) and fluorescence spectroscopy.  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