全文获取类型
收费全文 | 281篇 |
免费 | 21篇 |
专业分类
林业 | 19篇 |
农学 | 9篇 |
基础科学 | 8篇 |
69篇 | |
综合类 | 10篇 |
农作物 | 29篇 |
水产渔业 | 28篇 |
畜牧兽医 | 89篇 |
园艺 | 11篇 |
植物保护 | 30篇 |
出版年
2024年 | 1篇 |
2023年 | 3篇 |
2022年 | 7篇 |
2021年 | 8篇 |
2020年 | 14篇 |
2019年 | 15篇 |
2018年 | 18篇 |
2017年 | 12篇 |
2016年 | 8篇 |
2015年 | 9篇 |
2014年 | 10篇 |
2013年 | 22篇 |
2012年 | 17篇 |
2011年 | 20篇 |
2010年 | 12篇 |
2009年 | 10篇 |
2008年 | 18篇 |
2007年 | 11篇 |
2006年 | 16篇 |
2005年 | 9篇 |
2004年 | 7篇 |
2003年 | 10篇 |
2002年 | 11篇 |
2001年 | 3篇 |
2000年 | 1篇 |
1999年 | 3篇 |
1998年 | 2篇 |
1997年 | 2篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1993年 | 1篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 3篇 |
1988年 | 1篇 |
1985年 | 1篇 |
1983年 | 1篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1977年 | 3篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1973年 | 2篇 |
1972年 | 1篇 |
1968年 | 1篇 |
1935年 | 1篇 |
排序方式: 共有302条查询结果,搜索用时 0 毫秒
171.
Clauvis NT Taning Salvatore Arpaia Olivier Christiaens Antje Dietz‐Pfeilstetter Huw Jones Bruno Mezzetti Silvia Sabbadini Hilde‐Gunn Sorteberg Jeremy Sweet Vera Ventura Guy Smagghe 《Pest management science》2020,76(3):841-845
Facing current climate challenges and drastically reduced chemical options for plant protection, the exploitation of RNA interference (RNAi) as an agricultural biotechnology tool has unveiled possible new solutions to the global problems of agricultural losses caused by pests and other biotic and abiotic stresses. While the use of RNAi as a tool in agriculture is still limited to a few transgenic crops, and only adopted in restricted parts of the world, scientists and industry are already seeking innovations in leveraging and exploiting the potential of RNAi in the form of RNA‐based biocontrol compounds for external applications. Here, we highlight the expanding research and development pipeline, commercial landscape and regulatory environment surrounding the pursuit of RNA‐based biocontrol compounds with improved environmental profiles. The commitments of well‐established agrochemical companies to invest in research endeavours and the role of start‐up companies are crucial for the successful development of practical applications for these compounds. Additionally, the availability of standardized guidelines to tackle regulatory ambiguities surrounding RNA‐based biocontrol compounds will help to facilitate the entire commercialization process. Finally, communication to create awareness and public acceptance will be key to the deployment of these compounds. © 2019 Society of Chemical Industry 相似文献
172.
C. Kreye B.A.M. Bouman G. Reversat L. Fernandez C. Vera Cruz F. Elazegui J.E. Faronilo L. Llorca 《Field Crops Research》2009
Aerobic rice is a new production system for water-short environments. Adapted varieties are usually direct dry seeded and the crop grown under aerobic soil conditions with supplementary irrigation as necessary. Occasionally, yield failures occur which may be related to soil health problems. In the dry season of 2006 and 2007, we conducted a field experiment in the Philippines, to identify the major causes of such yield failure. Four treatments were implemented: (i) Control of direct dry-seeded rice (improved upland variety Apo), (ii) Biocide application, (iii) transplanting into aerobic soil, and (iv) 1 year fallow. Yield in the Biocide treatment was 2 t ha−1 in both years. In all other treatments, yield was 0–0.3 t ha−1. Plants grown in the Biocide treatment showed a reduced degree of galling of roots caused by root-knot nematodes (RKN) and better general root health than the Control treatment. Potentially pathogenic fungi were isolated from root samples (Pythium sp., Fusarium sp., and a Rhizoctonia-like species). Abiotic effects of the Biocide treatment were an increase in KCl-extractable N (initial season 2007) and a decrease in initial soil pH. In the Control treatment, soil pH increased from 6.5 to 8.0 over the two seasons. In 2007, plant tissue analysis indicated Mn deficiency in the Control treatment. Plants that were subjected to foliar micronutrient sprays reacted positively to Fe and Mn sprays in the Control treatment, and Mn spray in the Biocide treatment. We concluded that the Biocide application led to favorable soil conditions by reducing biotic stresses such as RKN and improving nutrient availability. In the other treatments, an interaction of RKN and micronutrient deficiencies with increasing soil pH led to yield failure. 相似文献
173.
Ezequiel Hidalgo-Hermoso Sebastin Celis Javier Cabello Ignacio Kemec Carolina Ortiz Rocio Lagos Juan Verasay Dario Moreira-Arce Pablo M. Vergara Frank Vera Fernando Espern 《The Veterinary quarterly》2023,43(1):1
Viral diseases jeopardize the health of wildlife in Chile. However, this country lacks health surveillance programs that allow for defining preventive measures to tackle such diseases. The objective of this study was to determine the occurrence and the genetic diversity of pestivirus, herpesvirus and adenovirus in pudus from Chile. Blood samples from wild (n=34) and captive (n=32) pudus were collected between 2011 and 2019 and analyzed through consensus PCR. All the samples were negative to pestivirus and adenovirus. Herpesvirus was confirmed in four captive, and one wild pudu. All four zoo animals share the same sequence for both polymerase and glycoprotein genes. Both sequences share a 100% identity with caprine herpesvirus-2, classifying them in the same cluster as the Macavirus group. In turn, novel sequences of the polymerase and glycoprotein B genes were obtained from the wild pudu. Our study reports the first evidence of CpHV-2 infection in Chile and South American ungulate populations. Further research will be necessary to assess the pathogenicity of CpHV-2 in this species. It is also urgently recommended that molecular, serological and pathological screening should be conducted in Chilean wild and captive pudus to understand the impact of the herpesvirus on their populations. 相似文献
174.
Carlos Carrasco-Muñoz de Vera 《Biological conservation》1977,11(1):5-11
This paper reviews the status, management and resources of National Parks in Spain. From 1954 to 1973 five new National Parks were created, in addition to those of Covadonga and Ordesa, covering 57,000 ha, although nearly all the land is now owned by the government. Resources provided for the maintenance of the Parks are inadequate and in 1974 amounted to only 12,200,000 pesetas (about £76,000 at 1974 exchange levels). In contrast much more money is provided for hunting and fishing reserves and more land is set aside for these purposes, although the benefits are enjoyed by a comparatively small number of people. Criticisms are made of the Institute for the Conservation of Nature (ICONA) for its short-sighted management policy and lost opportunities to improve the administration of the Parks. 相似文献
175.
Dall'aglio C Pascucci L Mercati F Giontella A Pedini V Ceccarelli P 《Research in veterinary science》2009,86(2):189-57
The aim of the present study was to investigate the presence and the distribution of cells containing orexin A and orexin type 2 receptor in the horse stomach and gut, by means of immunohistochemical techniques.Orexin A was identified in the stomach fundic and pyloric regions and in the duodenum. In the same stomach regions, a large subset of orexin A-positive cells also showed orexin type 2 receptor-like immunoreactivity. Moreover, in the duodenum, many of them, seemed to store serotonin.Characteristically, enteric neurons or ganglia also displayed orexin A and, sometimes, orexin type 2 receptor immunoreaction.Orexin A and orexin type 2 receptor immunoreactivity was also found in the nerve fibers in the enteric submucosal layer.Our results, together with data present in the literature, could contribute to the understanding of complex mechanisms regulating the horse gut functionality that are depending very likely on the consequence of the co-operation of both a central and a peripheral control. 相似文献
176.
Animal color patterns can affect fitness in the wild; however, little is known about the mechanisms that control their formation and subsequent evolution. We took advantage of two locally camouflaged populations of Peromyscus mice to show that the negative regulator of adult pigmentation, Agouti, also plays a key developmental role in color pattern evolution. Genetic and functional analyses showed that ventral-specific embryonic expression of Agouti establishes a prepattern by delaying the terminal differentiation of ventral melanocytes. Moreover, a skin-specific increase in both the level and spatial domain of Agouti expression prevents melanocyte maturation in a regionalized manner, resulting in a novel and adaptive color pattern. Thus, natural selection favors late-acting, tissue-specific changes in embryonic Agouti expression to produce large changes in adult color pattern. 相似文献
177.
Kogika MM Lustoza MD Notomi MK Wirthl VA Mirandola RM Hagiwara MK 《Veterinary clinical pathology / American Society for Veterinary Clinical Pathology》2006,35(4):441-445
BACKGROUND: Chronic renal failure (CRF) is a common disease in dogs, and many metabolic disorders can be observed, including metabolic acidosis and calcium and phosphorus disturbances. Acidosis may change the ionized calcium (i-Ca) fraction, usually increasing its concentration. OBJECTIVE: In this study we evaluated the influence of acidosis on the serum concentration of i-Ca in dogs with CRF and metabolic acidosis. METHODS: Dogs were studied in 2 groups: group I (control group = 40 clinically normal dogs) and group II (25 dogs with CRF and metabolic acidosis). Serum i-Ca was measured by an ion-selective electrode method; other biochemical analytes were measured using routine methods. RESULTS: The i-Ca concentration was significantly lower in dogs in group II than in group I; 56% of the dogs in group II were hypocalcemic. Hypocalcemia was observed in only 8% of dogs in group II when based on total calcium (t-Ca) concentration. No correlation between pH and i-Ca concentration was observed. A slight but significant correlation was detected between i-Ca and serum phosphorus concentration (r = -.284; P = .022), as well as between serum t-Ca and i-Ca concentration (r = .497; P < .0001). CONCLUSION: The i-Ca concentration in dogs with CRF and metabolic acidosis varied widely from that of t-Ca, showing the importance of determining the biologically active form of calcium. Metabolic acidosis did not influence the increase in i-Ca concentration, so other factors besides acidosis in CRF might alter the i-Ca fraction, such as hyperphosphatemia and other compounds that may form complexes with calcium. 相似文献
178.
The use of complementary and alternative medicine (CAM) by US consumers has grown in recent years. CAM therapies often utilize medicinal herbs as part of the treatment process; however, research on US practitioner preferences for medicinal herbs is limited, despite growing concern surrounding the sustainability of wild-harvested medicinal herbs. In order better to understand consumer preferences for this emerging market, a mail survey of US practitioners (licensed acupuncturists) was conducted to examine the importance of five herb attributes in practitioners?? herb selection decisions: (1) country of origin, (2) freshness, (3) production method (organic versus conventional), (4) price, and (5) traceability. The significance of these five traits is investigated using discrete choice analysis, and the implications for US medicinal herb growers are discussed. 相似文献
179.
Olszak T An D Zeissig S Vera MP Richter J Franke A Glickman JN Siebert R Baron RM Kasper DL Blumberg RS 《Science (New York, N.Y.)》2012,336(6080):489-493
Exposure to microbes during early childhood is associated with protection from immune-mediated diseases such as inflammatory bowel disease (IBD) and asthma. Here, we show that in germ-free (GF) mice, invariant natural killer T (iNKT) cells accumulate in the colonic lamina propria and lung, resulting in increased morbidity in models of IBD and allergic asthma as compared with that of specific pathogen-free mice. This was associated with increased intestinal and pulmonary expression of the chemokine ligand CXCL16, which was associated with increased mucosal iNKT cells. Colonization of neonatal-but not adult-GF mice with a conventional microbiota protected the animals from mucosal iNKT accumulation and related pathology. These results indicate that age-sensitive contact with commensal microbes is critical for establishing mucosal iNKT cell tolerance to later environmental exposures. 相似文献
180.
Robert-Tissot C Rüegger VL Cattori V Meli ML Riond B Moore PF Engels M Franchini M Hofmann-Lehmann R Lutz H 《Veterinary research》2012,43(1):60
ABSTRACT: Domestic cats are commonly affected by viral pathogens that induce lengthy infections with fatal outcomes. Prevention of viral propagation is of primordial importance in shelters and catteries, where cats from different backgrounds have narrow contacts. Oligonucleotides (ODN) containing cytosine-phosphate-guanosine motifs of class A (CpG-A) are highly potent synthetic inducers of innate antiviral mechanisms. The aim of this study was to test their ability to modulate innate immune responses and prevent viral replication as stand-alone agents in the domestic cat. CpG-A stimulation of feline peripheral blood mononuclear cells (PBMCs) enhanced their proliferation, increased the presence of co-stimulatory molecules on their surface and influenced their gene expression profiles in an antiviral orientation. Incubation of the supernatants of CpG-A stimulated PBMCs with feline cell lines of epithelial and fibroblastic origin induced expression of the antiviral myxovirus resistance (Mx) gene in these target cells, which also showed enhanced resistance to feline viruses from five distinct families, namely Coronaviridae, Herpesviridae, Caliciviridae, Parvoviridae, and Retroviridae. Most importantly, subcutaneous administration of CpG-A in domestic cats systemically increased the expression of Mx, reaching maximal levels within 24 h. Plasma from treated cats could furthermore inhibit viral replication in vitro. Altogether, our data highlight the promising potential of CpG-A to induce a preventive antiviral state in the cat and to protect feline populations against a broad range of virus infections. 相似文献