全文获取类型
收费全文 | 1515篇 |
免费 | 72篇 |
国内免费 | 1篇 |
专业分类
林业 | 145篇 |
农学 | 220篇 |
基础科学 | 23篇 |
311篇 | |
综合类 | 47篇 |
农作物 | 88篇 |
水产渔业 | 46篇 |
畜牧兽医 | 513篇 |
园艺 | 66篇 |
植物保护 | 129篇 |
出版年
2023年 | 10篇 |
2022年 | 23篇 |
2021年 | 33篇 |
2020年 | 31篇 |
2019年 | 27篇 |
2018年 | 67篇 |
2017年 | 56篇 |
2016年 | 68篇 |
2015年 | 38篇 |
2014年 | 40篇 |
2013年 | 123篇 |
2012年 | 56篇 |
2011年 | 77篇 |
2010年 | 56篇 |
2009年 | 45篇 |
2008年 | 68篇 |
2007年 | 54篇 |
2006年 | 47篇 |
2005年 | 40篇 |
2004年 | 34篇 |
2003年 | 40篇 |
2002年 | 41篇 |
2001年 | 28篇 |
2000年 | 27篇 |
1999年 | 29篇 |
1998年 | 13篇 |
1997年 | 9篇 |
1996年 | 15篇 |
1995年 | 11篇 |
1994年 | 10篇 |
1993年 | 11篇 |
1992年 | 18篇 |
1991年 | 20篇 |
1990年 | 30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 | 15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1588条查询结果,搜索用时 15 毫秒
41.
Tor tor is an important game and food fish of India with a distribution throughout Asia from the trans-Himalayan region to the Mekong River basin to Malaysia, Pakistan, Bangladesh and Indonesia. A new cell line named TTCF was developed from the caudal fin of T. tor for the first time. The cell line was optimally maintained at 28°C in Leibovitz-15 (L-15) medium supplemented with 20% fetal bovine serum (FBS). The propagation of TTCF cells showed a high plating efficiency of 63.00%. The cytogenetic analysis revealed a diploid count of 100 chromosomes at passage 15, 30, 45 and 60 passages. The viability of the TTCF cell line was found to be 72% after 6 months of cryopreservation in liquid nitrogen (-196°C). The origin of the cell lines was confirmed by the amplification of 578- and 655-bp sequences of 16S rRNA and cytochrome oxidase subunit I (COI) genes of mitochondrial DNA (mtDNA) respectively. TTCF cells were successfully transfected with green fluorescent protein (GFP) reporter plasmids. Further, immunocytochemistry studies confirm its fibroblastic morphology of cells. Genotoxicity assessment of H?O? in TTCF cell line revealed the utility of TTCF cell line as in vitro model for aquatic toxicological studies. 相似文献
42.
Ningthoujam Sandhyarani Rajkumar Kishor Gurumayum Jitendra Sharma 《Journal of Crop Science and Biotechnology》2011,14(3):213-217
Acorus calamus is an important medicinal plant which has been used in Indian traditional medicine since time immemorial. Various bioactive
molecules, viz., acorin, α- and β-asarone, asaryldehyde, caryophylene, isoasarone, methylisoeugenol, and safrol have been isolated from this
plant. However, the use of this plant for medicinal purpose has been recently banned due to the high toxic property of β-asarone.
The triploid Acorus calamus is reported to be low in β-asarone content and thus found to be the ideal raw material for medicinal use. The present investigation
represents our finding for successful in vitro clonal propagation of the elite triploid accessions of Acorus calamus for mass propagation. In the dual-phase culture system consisting of agar-solidified Murashige and Skoog medium overlaid
by liquid fraction of the same medium, maximum multiple shoot induction was favored by supplementation of α-naphthaleneacetic
acid (0.5 mg L−1) and 6-benzylaminopurine (2.0 mg L−1). In vitro rooting of the microshoots was maximum in the medium supplemented with indolebutyric acid at 2.0 mg L−1. The well-rooted microshoots could be successfully hardened and transplanted in the field. This result can be reproduced
and is a viable protocol for successful clonal propagation of the seedless triploid Acorus calamus for conservation and sustainable development. 相似文献
43.
Khem R. Sharma Pingsun Leung 《Aquaculture Economics & Management (Blackwell Science)》2013,17(3):129-140
Abstract Modern aquaculture is a relatively new activity among Nepalese farmers and a small contributor to the economy. Given the abundance of water resources and fish species, rising demand for fish, and its high profitability, aquaculture has potential for future expansion if it is given appropriate attention from the government. In Nepal, productivity in aquaculture is much lower compared to other countries in the region, which suggests that there is potential for increased fish production through technological progress and improvement in farm‐level technical efficiency. However, no formal analysis has yet been conducted to assess the productive performance of Nepalese aquaculture and its potential for future improvement. Against this background, this paper examines the technical efficiency and its determinants for a sample of fish pond farms from the Tarai region of the country using a stochastic production frontier involving a model for technical inefficiency effects. The estimated mean technical efficiency is 77%, with intensive farms being more efficient than extensive farms. The adoption of regular fish, water, and feed management activities has a strong positive effect on technical efficiency. 相似文献
44.
Sharma Luni Pipil Supriya Rawat Varunendra Singh Sehgal Neeta 《Fish physiology and biochemistry》2022,48(3):749-765
Fish Physiology and Biochemistry - Yolk processing pathways vary in the oocytes of benthophil and pelagophil teleosts. The present study investigated the yolk processing pattern in the oocytes of... 相似文献
45.
Canine influenza virus is an emerging, highly contagious, respiratory pathogen that has not previously been radiographically described. In this retrospective case series study, we describe the thoracic radiographic appearance of confirmed canine influenza virus in six dogs. Radiographic findings varied, but included abnormal unstructured interstitial (one) and unstructured interstitial and alveolar (five) pulmonary patterns, which were distributed cranioventral (four), diffuse (one), and caudodorsal (one). The right middle (five), left cranial (five), and right cranial (four) lung lobes were most commonly affected. Additionally, mild pleural effusion was present in one dog. Intrathoracic lymphadenopathy and cranial mediastinal widening/fluid accumulation were not detected in any dog. Canine influenza virus should be considered as a differential diagnosis for canine patients with respiratory signs and a cranioventral unstructured interstitial to alveolar pulmonary pattern. 相似文献
46.
Ranjan Bhattacharyya Arti Bhatia Birendra N. Ghosh Priyabrata Santra Debashis Mandal Gopal Kumar Raman Jeet Singh Madegowda Madhu Avijit Ghosh Arup K. Mandal Ranjan Paul Ashim Datta Parbodh C. Sharma Uttam K. Mandal Pramod Jha Kokkuvayil S. Anil Manickam Lalitha Mahesh Kumar Nav R. Panwar Dibyendu Sarkar Ashok K. Patra Sumanta Kundu Michael A. Fullen Jean Poesen Bhabani Sankar Das Nagarjuna N. Reddy Suresh K. Chaudhari 《European Journal of Soil Science》2023,74(4):e13388
Current widespread and intensive soil degradation in India has been driven by unprecedented levels of population growth, large-scale industrialization, high-yield agriculture, urban sprawl and the spread of human infrastructure. The damage caused to managed and natural systems by soil degradation threatens livelihoods and local services and leads to national socio-economic disruption. Human-induced soil degradation results from land clearing and deforestation, inappropriate agricultural practices, improper management of industrial effluents and wastes, careless management of forests, surface mining, urban sprawl, and ill-planned commercial and industrial development. Of these, inappropriate agricultural practices, including excessive tillage and use of heavy machinery, over-grazing, excessive and unbalanced use of inorganic fertilizers, poor irrigation and water management techniques, pesticide overuse, inadequate crop residue and/or organic carbon inputs, and poor crop cycle planning, account for nearly 40% (121 Mha) of land degradation across India. Globally, human activities related to agriculture contribute to the transgression of four of the nine Planetary Boundaries proposed by Rockström et al. (2009): Climate Change, Biodiversity Integrity, Land-system Change, and altered Phosphorus and Nitrogen Biogeochemical Flows. This review focuses on how knowledge of soil processes in agriculture has developed in India over the past 10 years, and the potential of soil science to meet the objectives of the United Nations' Sustainable Development Goal 2: Zero Hunger (End hunger, achieve food security, improved nutrition and promote sustainable agriculture), using the context of the four most relevant Planetary Boundaries as a framework. Solutions to mitigate soil degradation and improve soil health in different regions using conservation agricultural approaches have been proposed. Thus, in this review we (1) summarize the outputs of recent innovative research in India that has explored the impacts of soil degradation on four Planetary Boundaries (Climate Change, Biodiversity Loss, Land-system Change, and altered Biogeochemical Flows of Phosphorus and Nitrogen) and vice-versa; and (2) identify the knowledge gaps that require urgent attention to inform developing soil science research agendas in India, to advise policy makers, and to support those whose livelihoods rely on the land. 相似文献
47.
Polymerase chain reaction (PCR) was used to amplify the spacer regions between the 16S and 23S genes of rRNA genetic loci of Salmonella serovars for their rapid identification. These genetic loci revealed a significant level of polymorphism in length across the species/serovar lines. When the 16S-23S spacer region amplification products were subjected to agarose electrophoresis, the patterns observed could be used to distinguish all the serovars of Salmonella tested. Unique elements obtained in amplification products were mostly clustered at serovar level, although certain genus-specific patterns were also observed. On the basis of the results obtained, the amplification of 16S-23S ribosomal spacer region could suitably be used in a PCR-based identification method for Salmonella serovars. 相似文献
48.
Kumar N Sharma AK Sharma AK Kumar S 《Journal of veterinary medicine. A, Physiology, pathology, clinical medicine》2002,49(5):269-276
The efficacy of carbon fibres and plasma-preserved tendon allografts for gap repair in the superficial digital flexor tendon in the mid-metatarsal region was evaluated in 12 crossbred calves. Experimental tenectomies were performed, followed by implantation of carbon fibres in group I (12 legs) and plasma-preserved tendon allografts in group II (12 legs). Gross observations in group I showed filling of the defect with granulation tissue with more vascularity on day 7, which was less prominent at day 14. On day 30, the neotendon formed was slightly thicker and comparable to normal tendon in appearance and texture. On day 90, it exhibited all the characteristics of a fully developed tendon. Whereas, in group II increased vascularity at the site and encapsulation of the graft with connective tissue in early periods was observed. The gap between graft and host was filled with fibrous connective tissue. Peritendinous adhesions were maximum on day 7 which were gradually reduced in both groups. Microscopically, an acute inflammatory reaction in the periphery of carbon fibres was observed on day 7. Immature fibroblasts were arranged in a haphazard pattern at this stage. By day 14, numerous newly formed capillaries and comparatively more mature fibroblasts were present in between and around the carbon fibres which were aligning parallel to the longitudinal axis of the tendon. By day 30 the healing tissue exhibited longitudinal orientation of collagen fibres and was at a more advance stage of maturation. By day 90, the neotendon formed simulated the picture of normal tendon. In the grafted tendon group, there was normal healing tissue at the functional sites between host and grafted tendon. The fibroblastic activity appeared to be both extrinsic and intrinsic in origin. The connective tissue had invaded the graft to a variable distance and there was resorption of graft which was replaced by newly formed connective tissue on day 90. Scanning electron microscopic observation revealed formation of neotendon between carbon fibre strands, resulting in thickening of the implant. In later stages parallel collagen fibres resembling normal tendon were observed in both groups. 相似文献
49.
50.
H. C. Sharma M. P. Bhagwat G. Pampapathy J. P. Sharma T. J. Ridsdill-Smith 《Genetic Resources and Crop Evolution》2006,53(1):131-138
The legume pod borer, Helicoverpa armigera (Hübn.), is one of the major constraints to chickpea production, and host plant resistance is an important component for
the management of this pest. The levels of resistance in the cultivated chickpea are low to moderate, and therefore, we evaluated
17 accessions of perennial Cicer along with three cultivated chickpea genotypes for resistance to H. armigera. There was a significant reduction in both leaf feeding and larval weights when the larvae were fed on the leaves of Cicer microphyllum Benth. accessions ICC 17146, ICC 17236, ICC 17240, and ICC 17248. Relative resistance index based on leaf feeding, larval
survival, and larval weight indicated that C. microphyllum accessions ICC 17146, ICC 17236, ICC 17234, ICC 17240, ICC 17243, and ICC 17248 were highly resistant to H. armigera. Under natural infestation, accessions belonging to C. microphyllum, C. canariense Santos Guerra et Lewis, and C. macracanthum M. Pop suffered a damage rating of <2.0 compared to 4.0 in C. judaicum Boiss. accession ICC 17148 (annual species) and 8.5–9.0 in the cultivated chickpeas (1 = <10% leaf area damaged, and, 9 = >80%
leaf area damaged). There was considerable diversity in the accessions belonging to perennial wild species of chickpea, and
these can be exploited to increase the levels and diversify the basis of resistance to H. armigera in the cultivated chickpea. 相似文献