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   178篇
  免费   6篇
林业   9篇
农学   25篇
基础科学   2篇
  29篇
综合类   6篇
农作物   27篇
水产渔业   14篇
畜牧兽医   42篇
园艺   10篇
植物保护   20篇
  2023年   2篇
  2022年   5篇
  2020年   6篇
  2019年   5篇
  2018年   8篇
  2017年   4篇
  2016年   8篇
  2015年   9篇
  2014年   13篇
  2013年   18篇
  2012年   11篇
  2011年   14篇
  2010年   7篇
  2009年   5篇
  2008年   5篇
  2007年   2篇
  2006年   5篇
  2005年   5篇
  2004年   4篇
  2003年   3篇
  2002年   4篇
  2001年   4篇
  2000年   1篇
  1999年   2篇
  1997年   1篇
  1996年   1篇
  1995年   1篇
  1991年   5篇
  1990年   1篇
  1988年   3篇
  1987年   3篇
  1986年   3篇
  1985年   1篇
  1982年   1篇
  1981年   1篇
  1979年   5篇
  1978年   1篇
  1975年   1篇
  1971年   1篇
  1970年   1篇
  1969年   2篇
  1967年   1篇
  1966年   1篇
排序方式: 共有184条查询结果,搜索用时 15 毫秒
101.
Seedlings of Syzygium cumini were grown in artificially salinized soils of conductivities 0 to 20 mmhos cm-1 for 19 months. Adverse effects on growth were seen at and above a conductivity level of 16 mmhos cm-1 of the saturation extract. As the conductivity increased, the adverse effects of growth and the extent of plant injury were intensified As salinity increased, the leaf chlorophyll content at the end of the experiment decreased. The leaf N content did not differ significantly, but the root N content was significantly lower at higher salinity levels. With increased salinity the K, Ca, Mg, Zn and Fe in the leaves and roots lessened, but leaf Na rose in concentration with increasing salinity. The Mn and Cu contents of leaves and roots did not differ significantly.  相似文献   
102.
Plant height is one of the most important agronomic traits in sorghum with its relevance for biomass, grain yield, fodder and lodging. To understand its genetic basis, the quantitative trait loci (QTL) were identified using a recombinant inbred line (RIL) population consisting of 168 RILs derived from the cross between the two sorghum inbred lines 296B (dwarf) and IS18551 (tall) over six seasons. Two major QTL were identified one each on chromosomes SBI-06 and SBI-07 corresponding to the Dw2 and Dw3 gene loci together accounting 41 % plant height variation. In addition, a morphological bloom trait locus which remained unlinked in the linkage map was found to be significantly linked with plant height in single marker analysis explaining 22 % of the trait variation. By comparing the map positions of Dw1, Dw2 and Dw3, the new locus for plant height linked with bloom is proposed as Dw4 locus. Both SSR and the morphological bloom loci linked with height QTL of the present study can be employed as effective tools in marker-assisted breeding for rapid conversion of selected inbred parent lines either as dwarf seed (male sterile) parents or taller pollinators for hybrid seed industry, or for developing high biomass lines in sweet sorghum for exploitation as high bio-fuel crop.  相似文献   
103.
Rice blast, caused by fungus Magnaporthe grisea, is a serious disease causing considerable economic damage worldwide. Best way to overcome disease is to breed for disease‐resistant cultivars/parental lines of hybrids. Pusa RH10, first aromatic, fine‐grain rice hybrid released and cultivated extensively in India. Hybrid and its parental lines, Pusa 6A and PRR78, are highly susceptible to blast. CO39 pyramid carrying two dominant, broad‐spectrum blast‐resistance genes, viz. Pi‐1 and Piz‐5, used as a donor parent to introgress these genes into PRR78 using marker‐assisted backcrossing (MABC). Microsatellite markers RM5926 and AP5659‐5 tightly linked to Pi‐1 and Piz‐5 genes, respectively, were used for foreground selection to derive introgression lines. Further, these lines were evaluated for agronomic performance, disease reaction and cooking quality traits along with PRR78. Most of the improved lines were on par with PRR78 for all traits evaluated except gelatinization temperature. Recurrent parent genome percentage (RPG) study also revealed similarity of these lines with PRR78. Hybrids derived using improved PRR78 lines were superior over Pusa RH10 in terms of yield.  相似文献   
104.
The effects of extracts of different parts of the perennial tropical plant Balanites aegyptiaca (L) Del., including various solvent extracts of roots, methanol extracts from leaves, fruits, flowers and roots, partially purified saponins obtained from its roots and a standard saponin were studied on the life cycle (adult longevity, number of eggs, crawlers, adults, weight of adults and % wax content) of a laboratory-reared parthenogenic line of the mealy bug, Maconellicoccus hirsutus (Homoptera: Pseudococcidae). Extracts derived from various parts of B. aegyptiaca (leaves, fruits, flowers, and roots in methanol) affected the life cycle of M. hirsutus with a methanol root extract being the most effective at a concentration of 500 μg ml−1. Partially purified saponin of B. aegyptiaca and the commercial bark saponin extract (Sigma) from Quillaja saponaria at a concentration of 500 μg ml−1 were effective in reducing the longevity of M. hirsutus. Significant reductions in oviposition by M. hirsutus were found for all the extracts at a concentration of 500 μg ml−1. Extracts also affected the number of emerging crawlers, number of adults as well as the weight and wax content of emerging adults. These studies suggest that B. aegyptiaca plant extracts and saponins can be useful botanical insecticides for the protection of crops from mealy bugs.  相似文献   
105.
The life cycle of a laboratory reared parthenogenic line of mealybug, Maconellicoccus hirsutus (Green) (Hemiptera: Pseudococcidae) was investigated on six host plants (Lagenaria siceraria var.clavata, Solanum tuberosum L. var. Kufri Chandramukhi, Praecitrullus fistulosus (Stocks) Pangalo var. MTNH1, Cucurbita pepo var. Styriaca, Triticum aestivum L. var. Lokvan, H. rosa sinensis L.) at five constant temperatures (25, 29, 35, 38, 42 °C). The number of emerging crawlers and adults as well as weight of adults varied with host and temperature. P. fistulosus and H. rosa sinensis were suitable hosts for laboratory rearing of M. hirsutus. However, ease of maintenance of P. fistulosus to produce M. hirsutus under laboratory conditions is an additional advantage compared to using green plants such as H. rosa sinensis. Among the range of constant temperatures, 38 °C was found to be the most favourable for the development and survival of M. hirsutus. These results suggest that P. fistulosus fruits are suitable hosts for laboratory rearing and life cycle studies of M. hirsutus.  相似文献   
106.
This study was designed to quantify the total water requirement and consumptive water use in carp‐prawn polyculture system under different water management protocols, using water balance model. Under different water management protocols, treatment‐wise estimated total water use, TWU (×104, m3) was 3.7, 4.6 and 3.9, while the computed consumptive water use index, CWUI (m3 kg?1 biomass) was 6.62, 9.31 and 7.08, in T1 (no water exchange), T2 (periodic water exchange) and T3 (regulated water exchange) respectively. Significantly higher yield (P < 0.05) in both T2 and T3 over T1, was probably due to water exchange that improved the rearing environment. Although intensity of water exchange was more in T2, significant variation (P < 0.05) in overall growth and yield was not recorded between T2 and T3. Treatment‐wise sediment load ranged between 54.6 and 71.3 m3 t?1 biomasses. Higher sediment load was recorded at lower intensity of water exchange as well as with higher apparent feed conversion ratio. Higher net total water productivity, net consumptive water productivity and OV‐CC ratio in T3 infers that regulated water exchange has a distinct edge over the no water exchange protocol. Restricted water use instead of regular/excess water exchange not only improves the production performance and water productivity, but also helps in lessening the operational pumping cost.  相似文献   
107.
A study was conducted to evaluate the effect of an immunostimulant product prepared from vibrio bacterial components on production of Penaeus monodon culture in five commercial shrimp farmer’s ponds in the Navsari district of Gujarat. The product was administered at the concentration of 2 × 108 cfu/kg pelleted feed as top dressing using a commercial binder for two consecutive days in a week. In general, we observed improvement of up to 33.33% in average body weight, up to 44.83% in survival rate, up to 11.11% in FCR, and up to 50.00% in production per ha over untreated control ponds on the same farm. Administration of this vibrio bacterial product could improve shrimp production in Gujarat.  相似文献   
108.
109.
Despite reports of BVDV infection in several domestic and wild ruminants, no information exists for mithun (Bos frontalis) species. Hence, this study was undertaken to determine prevalence of BVDV infection in mithuns, which contribute significantly to local economy in the North Eastern region of India. Blood and serum samples were collected between 2013 and 2016 from mithuns (n = 466) belonging to the states of Nagaland, Mizoram, and Arunachal Pradesh. Serum samples were tested for BVDV antibodies by a commercial ELISA and leukocytes were tested for BVDV by real-time RT-PCR. The overall true seroprevalence rate was 13.1% (95% confidence interval, CI: 6.9–17.8%) with higher prevalence in mithuns reared under semi-intensive system (27.5%) than in free-ranging mithuns (7.6%). Among the three states, seroprevalence (16.2%) was highest in Nagaland, while prevalence rates varied markedly among geographical locations. Age-wise data showed highest seroprevalence rate in >6-year-old animals (20.6%) than 2–6 years old (16.9%), 6 months–2 years old (8.5%), and <6-month-old animals (11.3%). The seroprevalence was higher in males (20.9%) than in females (12.1%). Among the four mithun strains, higher prevalence was evident in Manipur (30.3%) than Arunachal (21.3%), Nagaland (11.7%), and Mizoram strain (10.2%). However, no BVDV genomic RNA could be detected. The results provide first serological evidence of BVDV infection in mithun species and extend the knowledge on BVDV host range. The baseline data will help further investigations on epidemiology of BVD in mithun and its impact on mithun production.  相似文献   
110.
Lack of variability in sorghum is the main reason for the stagnation in crop improvement including low heterosis. Studies on somaclonal mutations of sorghum have led to the development of a diverse axillary branched grain sorghum mutant, SbABM of postrainy season variety A‐1 (Annigeri‐1) which bears multiple panicles. Considering its developmental significance and phenotypic diversity, this mutant was subjected to detailed genetic analysis. To exploit its genetic potentiality, the mutant was involved in a full diallel study along with ruling varieties to assess the combining ability and to quantify the magnitude of heterosis. SbABM performed exceptionally well in hybrid combinations for all the traits. Mean squares due to genotypes were highly significant for all the traits. The results on general combining ability revealed that SbABM was significantly better general combiner for all the traits studied. Majority of the hybrids involving SbABM as parental line exhibited high degree of heterosis for most of the traits, finally contributing to overall plant's vigour. However, SbABM did not restore fertility on both milo and maldandi cytoplasm.  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