全文获取类型
收费全文 | 1544篇 |
免费 | 89篇 |
国内免费 | 1篇 |
专业分类
林业 | 141篇 |
农学 | 223篇 |
基础科学 | 23篇 |
304篇 | |
综合类 | 50篇 |
农作物 | 92篇 |
水产渔业 | 46篇 |
畜牧兽医 | 559篇 |
园艺 | 66篇 |
植物保护 | 130篇 |
出版年
2023年 | 12篇 |
2022年 | 22篇 |
2021年 | 33篇 |
2020年 | 32篇 |
2019年 | 24篇 |
2018年 | 69篇 |
2017年 | 61篇 |
2016年 | 75篇 |
2015年 | 42篇 |
2014年 | 46篇 |
2013年 | 130篇 |
2012年 | 58篇 |
2011年 | 78篇 |
2010年 | 58篇 |
2009年 | 47篇 |
2008年 | 69篇 |
2007年 | 57篇 |
2006年 | 48篇 |
2005年 | 41篇 |
2004年 | 34篇 |
2003年 | 40篇 |
2002年 | 41篇 |
2001年 | 28篇 |
2000年 | 26篇 |
1999年 | 29篇 |
1998年 | 13篇 |
1997年 | 10篇 |
1996年 | 16篇 |
1995年 | 11篇 |
1994年 | 12篇 |
1993年 | 11篇 |
1992年 | 18篇 |
1991年 | 20篇 |
1990年 | 31篇 |
1989年 | 21篇 |
1988年 | 14篇 |
1987年 | 20篇 |
1986年 | 17篇 |
1985年 | 17篇 |
1984年 | 11篇 |
1983年 | 12篇 |
1982年 | 14篇 |
1981年 | 17篇 |
1980年 | 14篇 |
1979年 | 21篇 |
1978年 | 15篇 |
1977年 | 11篇 |
1970年 | 8篇 |
1969年 | 14篇 |
1968年 | 12篇 |
排序方式: 共有1634条查询结果,搜索用时 15 毫秒
1.
2.
Toxicological effects and recovery of the corneal epithelium in Cyprinus carpio communis Linn. exposed to monocrotophos: an scanning electron microscope study 下载免费PDF全文
Ravneet Kaur Uppal Mohinder Singh Johal Madan Lal Sharma 《Veterinary ophthalmology》2015,18(3):214-220
This study was conducted based on the evidence of fish habitats in North India being affected by organophosphate pesticides draining from agricultural fields into bodies of water, especially during the rainy season. Various tissues of fish such as scales, gills ovaries, kidney, and liver have been studied from the toxicological point of view, but the toxicological effects of aquatic pollutants on fish cornea have not been investigated to date. We conducted comparative toxicological studies on the cornea of Cyprinus carpio communis using two sublethal (0.038 and 0.126 ppm) concentrations of monocrotophos pesticide for 30 days. Corneas from all the groups were evaluated by a scanning electron microscope. The fish exposed to the monocrotophos pesticide developed corneal necrosis due to the formation of crystalloid‐like structures, thinning and shrinkage of microridges on the corneal epithelium. After 30 days, fish from the monocrotophos‐treated tank were transferred to normal environmental conditions. After 60 days under natural condition, epithelial cells did not fully recover. In conclusion, exposure to monocrotophos induces irreversible changes in the cornea of C. carpio communis. As fish and mammalian visual systems share many similarities, the reported finding may offer useful insights for further toxicological and ophthalmological studies in humans. 相似文献
3.
True-to-type clonal fidelity is one of the most important pre-requisites in micropropagation of crop species. Genetic fidelity of in vitro raised 45 plants of gerbera (Gerbera jamesonii Bolus) derived from three different explants, viz., capitulum, leaf and shoot tips, was assessed by 32 ISSR markers, for their genetic stability. Out of 32 ISSR markers, 15 markers produced clear, distinct and scorable bands with an average of 5.47 bands per marker. The markers designed from AG motif amplified more number of bands. The markers anchored at 3′ ends produced high number of consistent bands than unanchored markers. Fifteen ISSR markers generated a total of 3773 bands, out of which 3770 were monomorphic among all the clones. The Jaccard's similarity coefficient revealed that out of 45 clones derived from different explants, 44 were grouped into a single large cluster alongwith the mother plant with a similarity coefficient value of 1.00, whereas one clone (C38) remained ungrouped. The clones derived from capitulum and shoot tip explants did not show any genetic variation, whereas, one of the leaf-derived clones exhibited some degree of variation. 相似文献
4.
Nirmala Sehrawat Mukesh Yadav Anil Kumar Sharma Vikas Kumar Kangila Venkataraman Bhat 《Archives of Agronomy and Soil Science》2019,65(9):1287-1301
Mungbean is an important food grain legume with high economic status. It has an excellent source of dietary protein and nutritional health benefits, particularly for the vegetarians. It increases soil fertility and also plays an imperative role in major cropping systems due to its short life span. Production of mungbean is still decreasing due to its susceptibility towards various environmental stress factors. Salt stress is one of the most prevailing abiotic stress imposing threats for agriculture food crops along with increasing world population and limited natural resources. Fewer efforts have been made to develop an improved variety of mungbean. The present review summarizes the adverse effects of salt stress and mungbean response at the physiological and molecular level. It covers recent studies on introgression of useful traits in mungbean for its better adaptability and survival under stressed conditions. Modern biotechnological approaches and traditional breeding methods may assist the development of salt-tolerant cultivars of mungbean for salinity-affected area in arid and semi-arid regions. Researchers involved in this area should keep this goal on priority for sustainable mungbean production. Availability of protein-rich food may help to reduce the problem of malnutrition in poor families and national food security issue for a continuous rising population. 相似文献
5.
Manjeet B. L. Pander R. Sharma S. S. Dhaka Ankit Magotra Kapil Dev 《Tropical animal health and production》2017,49(8):1689-1695
Foot and mouth disease (FMD) is the most contagious disease of mammals and a major threat to animal husbandry sector. In India, vaccination with the inactivated trivalent (O, A and Asia1) vaccine is one proven way for protecting the livestock from FMD. However, many outbreaks have been reported in different parts of the country. Therefore, present study was aimed at elucidating the effects of genetic and non-genetic factors on FMD viral vaccine-elicited immune response in Hardhenu cattle. The effect of season of vaccination was not consistent. The effect of status of animal was significant for all the pre and post AB titres except for pre AB titre of serotype O and post AB titre of Asia1.The estimates of heritability for response to vaccination were low to high ranging from 0.11 to 0.45. The highest heritability estimate was obtained for serotype O and the lowest for Asia1. The heritability estimates for pre and post AB titres ranged from 0.15 to 0.33. All the pre and post AB titres and responses to vaccination had genetic correlations ranged from high negative to high positive among them. Results of this study highlight the variation in vaccine response which needs to be further exploited on large-scale animal data for better immunization and protection against highly contagious viral vesicular disease of cloven-hoofed animals. 相似文献
6.
Shailendra Kumar Yadav U. U. Khokhar Som Dev Sharma Pramod Kumar 《Journal of plant nutrition》2016,39(2):194-203
The aim of this research was designed in order to optimize integrated plant nutrient supply (IPNS) through balanced fertilization of organic, inorganic and microbial inoculants in strawberry cv. Chandler. The potential efficiency of bio-organics used along with chemical fertilizers on cropping behaviour, physical-chemical and biological properties of rhizosphere soil, fruit yield, quality attributes and leaf nutrient content was investigated. The significant improvement in physico-chemical properties of the soil and nutrient uptake was recorded. The uninoculated control received farmyard manure (FYM) and inorganic nitrogen (N) recorded the highest cation exchange capacity (CEC) and soil organic carbon (OC) content. Highest available N and phosphorus (P) of soil were recorded in vermicompost and inorganic N applied in two and one split, respectively. The concentration of micronutrients cations viz., iron (Fe), zinc (Zn), manganese (Mn) in soil was higher in treatment received vermicompost and inorganic N in two splits. The integration of bio-organic nutrient supplements also significantly enriched the microbial status of the rhizosphere soil, leaf nutrient concentration and maintained soil health and productivity on long term basis for sustainable fruit production. 相似文献
7.
Jasmonic and salicylic acid-induced resistance in sorghum against the stem borer Chilo partellus 总被引:1,自引:0,他引:1
Induced resistance was studied in three sorghum genotypes (IS2205, ICSV1 and ICSV700) against Chilo partellus (Swinhoe) (Lepidoptera; Pyralidae) infestation and jasmonic acid (JA) and salicylic acid (SA) application. The activity of plant defensive enzymes [peroxidase (POD), polyphenol oxidase (PPO), superoxide dismutase (SOD), and catalase (CAT)], and the amounts of total phenols, hydrogen peroxide (H2O2), malondialdehyde (MDA), and proteins were recorded at 6 days after infestation. The induction of enzyme activities and the amounts of secondary metabolites varied among the genotypes and treatments. The genotype IS2205 showed a stronger effect than that of ICSV1 or ICSV 700. Treatment with JA followed by insect infestation induced greater levels of enzymes and secondary metabolites. The results suggest that JA induces greater levels of resistance components in sorghum plants against insect pests. Thus, pretreatment of plants with elicitors including JA and SA could provide a greater opportunity for plant defense against herbivores. 相似文献
8.
Sharma RK Blair HT Jenkinson CM Kenyon PR Cockrem JF Parkinson TJ 《Journal of animal science》2012,90(4):1338-1348
Pure-bred embryos were transferred within and reciprocally between large (Suffolk) and small (Cheviot) breeds of sheep to establish 4 treatment groups: SinS (Suffolk embryos in Suffolk dams), SinC (Suffolk embryos in Cheviot dams), CinS (Cheviot embryos in Suffolk dams), and CinC (Cheviot embryos in Cheviot dams). The recipient ewes carried single fetuses to term. The maternal plasma concentrations of ovine placental lactogen (oPL), progesterone, IGF-1, FFA, and glucose were measured on d 50, 90, 120, and 140 of pregnancy. Birth weight, body dimensions, and placental characteristics of lambs were recorded at birth. There was a recipient ewe breed × lamb breed × time interaction for the concentration of oPL (P = 0.03), but no such interaction was observed for progesterone (P = 0.42), IGF-1 (P = 0.57), glucose (P = 0.36), or FFA (P = 0.72). There were no differences in oPL (P = 0.28) and progesterone (P = 0.34) concentrations between SinC and SinS ewes. The concentrations of FFA on d 140 (P = 0.008), and those of glucose on d 50 (P = 0.02) and 120 (P = 0.01), were greater in SinC ewes than in SinS ewes. The ewes in CinS had less FFA concentration (P = 0.002) at all time points than CinC ewes. The concentrations of IGF-1 on d 90 were greater (P = 0.004) in CinS ewes than CinC ewes, but did not differ (P = 0.16) on d 50, 120, and 140. The concentrations of glucose on d 50 (P = 0.001), 90 (P = 0.03), and 140 (P = 0.03) were less in CinS ewes compared with CinC ewes. The birth weight of SinC lambs (5.04 ± 0.20 kg) was lighter (P = 0.001) than SinS lambs (5.94 ± 0.19 kg), and body dimensions of SinC lambs were smaller (P = 0.01) than SinS lambs. Neither birth weight nor the body dimensions of CinS lambs differed (P = 0.24) from CinC lambs. Cotyledon number was reduced (P = 0.04) in the CinS (57.5 ± 6.3) compared with the SinS group (74.2 ± 5.9), whereas mean cotyledon weight in CinS (2.42 ± 0.20 g) was greater (P = 0.02) than SinS (1.74 ± 0.21 g). It was concluded that the large genotype lambs were lighter and smaller when born to small genotype dams; however, the birth weight or body dimensions of small genotype lambs did not differ when born to large genotype dams. This study suggests that plasma oPL, progesterone, IGF-1, FFA, and glucose concentrations at different times throughout pregnancy reflect the regulatory effect of the uterine environment on the development of the fetus. 相似文献
9.
Saxena MK Kumar AA Chaudhari P Shivachandra SB Singh VP Sharma B 《Veterinary research communications》2005,29(6):527-535
The applicability of ribotyping based on 16S and 23S rRNA was evaluated for molecular epidemiological studies. Forty-eight
isolates of Pasteurella multocida isolated from different hosts and geographical locations and one reference isolate were ribotyped. Only four ribotypes were
found. All the isolates including reference isolate from wild carnivores had the same ribotype, though they had different
serotypes. The isolate from a tiger had one band in addition to the bands present in the major ribotype. The isolates from
lions represented two ribotypes; of these ribotypes, one (r2) had an additional band of 3.6 kbp, which was absent in all other
ribotypes. The second ribotype (r4) from a lion had one band missing (6 kbp) that was present in the other ribotypes. These
isolates were further typed using ERIC-PCR and REP-PCR. With ERIC-PCR and REP-PCR, higher D values of 0.83 and 0.89 were obtained. The current study revealed that ribotyping is not a very efficient typing tool for
use in molecular epidemiology for differentiation of isolates. 相似文献
10.
R.G. Saini M. Kaur B. Singh Shiwani Sharma G.S. Nanda S.K. Nayar A.K. Gupta S. Nagarajan 《Euphytica》2002,124(3):365-370
The genetic bases of leaf rust resistance in wheat (Triticum aestivum L.) line CSP44, selected from the Australian cultivar Condor, and Indian cultivar VL404, were studied. The reaction patterns
of CSP44 and VL404 against Indian races 12, 77, 77-1, 77-2, 77-3, 77-4, 77-5 and 108 were different from reaction patterns
shown by near-isogenic lines with known adult plant resistance (APR) genes, viz. Lr12, Lr13, Lr22b and Lr34. Although the reaction patterns of CSP44 and VL404 were similar to the near-isogenic line Tc+Lr22a, tests of allelism indicated absence of Lr22a in both CSP44 and VL404. On the basis of genetic studies, their resistances in field tests against race 77-5, the most virulent
race from the Indian sub-continent, were each ascribed to two genes. One of the two genes in each wheat was identified to
be the non-hypersensitive APR gene Lr34. The second APR genes in CSP44 and VL404 gave hypersensitive reaction types and were recessive and dominant, respectively.
The gene in CSP44 was designated Lr48and the gene in VL404, Lr49.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献