全文获取类型
收费全文 | 322篇 |
免费 | 23篇 |
专业分类
林业 | 16篇 |
农学 | 15篇 |
基础科学 | 2篇 |
113篇 | |
综合类 | 12篇 |
农作物 | 20篇 |
水产渔业 | 41篇 |
畜牧兽医 | 92篇 |
园艺 | 4篇 |
植物保护 | 30篇 |
出版年
2023年 | 6篇 |
2022年 | 4篇 |
2021年 | 16篇 |
2020年 | 17篇 |
2019年 | 18篇 |
2018年 | 21篇 |
2017年 | 16篇 |
2016年 | 18篇 |
2015年 | 12篇 |
2014年 | 9篇 |
2013年 | 13篇 |
2012年 | 24篇 |
2011年 | 27篇 |
2010年 | 14篇 |
2009年 | 11篇 |
2008年 | 24篇 |
2007年 | 16篇 |
2006年 | 22篇 |
2005年 | 11篇 |
2004年 | 9篇 |
2003年 | 13篇 |
2002年 | 7篇 |
2001年 | 3篇 |
2000年 | 2篇 |
1999年 | 1篇 |
1998年 | 3篇 |
1996年 | 1篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1990年 | 1篇 |
1986年 | 1篇 |
1984年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
排序方式: 共有345条查询结果,搜索用时 484 毫秒
301.
A two‐and‐a‐half year‐old male Chinese hamster (Cricetulus griseus) was referred for evaluation of an intraorbital mass involving the right eye. Based on ophthalmic examination and ultrasonography, a diagnosis of intraocular neoplasia was made. Enucleation of the affected eye was performed. The mass was histologically diagnosed as a primary malignant intraocular signet‐ring cell melanoma. No signs of recurrence were detected, and the hamster remained clinically healthy until it died 6 months after surgery. This case report attempts to contribute to the limited body of knowledge available in the literature on primary intraocular neoplasms in hamsters. 相似文献
302.
Pérez-Sirkin Daniela Irina Di Yorio María Paula Delgadin Tomás Horacio Honji Renato Massaaki Moreira Renata Guimarães Somoza Gustavo Manuel Vissio Paula Gabriela 《Fish physiology and biochemistry》2021,47(5):1527-1540
Fish Physiology and Biochemistry - Many teleost fishes can withstand long feed deprivation periods, either due to an eventual lack of food or because of their behavior during reproduction and/or... 相似文献
303.
Juan Pablo Alcántar-Vázquez Silvie Dumas Eleonora Puente-Carreón Hugo Skyol Pliego-Cortés & Renato Peña 《Aquaculture Research》2008,39(1):59-63
Conditions for the induction of triploidy with cold shock of fertilized eggs of the spotted sand bass Paralabrax maculatofasciatus (Steindachner) were investigated. Different temperatures (12, 8 and 4 °C), timing of cold shock application (5, 10 and 15 min after fertilization) and duration of the shock (5, 10, 15 and 20 min) were tested. Triploidy was determined using flow cytometry at 12 h after larvae hatched. Triploids were produced only when the cold shock treatment was applied 5 min after fertilization. No significant difference was observed in the percentage of triploidy between temperature and the shock duration. At 8 and 4 °C, 100% triploidy was obtained at different durations of cold shock. Survival was significantly lower at 12 or 4 °C than at 8 °C. No significant difference was observed for shock duration at the temperature of 8 or 12 °C; however, at 4 °C, survival was significantly lower at longer durations. We recommend induction of triploidy by applying cold shock at 8 °C for a duration of 15–20 min starting at 5 min after fertilization, in the spotted sand bass. 相似文献
304.
Renato Bruni Maria Grazia Bellardi Giuseppe Parrella Alberto Bianchi 《Physiological and Molecular Plant Pathology》2006,68(4-6):189-197
Lavandula vera D.C., Lavandula×alardii and eight different L. hybrida Rev. cultivars cultivated at the Herb Garden of Casola Valsenio (Italy), found naturally infected by Alfalfa mosaic virus (AMV), have been evaluated for the influence of their pathologic status on essential oil biosynthesis and quality. The viral disease, consisting of a “yellow mosaic” on leaves and stems, was identified by means of electron microscopy, RT-PCR-RFLP and PAS-ELISA assays. Molecular characterization of the coat protein gene of four AMV isolates suggested that three of them belonged to subgroup I (from cvs. Ordinario and Grosso, Lavandula×alardii), while the isolate from cv. Sumiens showed molecular features of subgroup II. The infection of Lavandula plants by AMV (of the two subgroups) was found to decrease essential oil secretion. Changes in the relative composition regarded the linalool-linalyl acetate ratio; the overall increase in terpenic esters and in some cases increased sesquiterpenic abundance. Infection caused by AMV subgroup II isolate influenced negatively the quality of the essential oil much more than AMV isolates belonging to subgroup I. The importance of the phytopathological status of essential oil bearing crops is outlined. 相似文献
305.
Agostina Chiavola Renato Baciocchi Federico Barducci 《Water, air, and soil pollution》2010,211(1-4):219-229
Mercury pollution in the Second Songhua River (SSR) was serious in the last century due to effluent from a chemical corporation. Effects of riverine self-purification on mercury removal were studied by comparing monitoring data of mercury concentrations varieties in water, sediment, and fish in the past, about 30 years. The present work suggested that a river of such a size like the SSR possessed the potential ability to recover from mercury pollution under the condition that mercury sources were cut off, though it needs a very long time, which might be several decades or even a century of years. During the 30 years with no effluent containing mercury input, total mercury (T-Hg) of water and sediment in some typical segments, mostly near the past effluent outlet, had decreased radically but still higher than the background values, though the decrease amplitudes were over 90% compared with that in 1975. T-Hg had decreased by more than 90% in most fishes, but some were still not suitable for consumption. Methylmercury concentrations (MeHg) of water, sediment, and fish were higher or close to the background levels in 2004. In the coming decades, the purification processes in the SSR would be steady and slow for a long period. 相似文献
306.
Iram Zavala‐Leal Silvie Dumas Renato Peña Mauricio Contreras‐Olguín Dora Hernández‐Ceballos 《Aquaculture Research》2013,44(9):1399-1406
Feeding incidence or number of larvae with preys (FIC) and intensity or number of prey per larvae (FIT) at first feeding of Pacific red snapper ( Lutjanus peru) larvae was investigated under different conditions: prey type (rotifer and copepod nauplius) and density, nauplii size, light intensity, water temperature, salinity and microalgae concentration. Rotifers were not consumed at any prey density and FIC increased significantly when a high nauplii density (10 > 1, 0.1 mL?1) and light intensity (2000 > 1000, 500, 0 lx) were supplied. In a multifactorial experiment where light intensity (2000, 2500, 3000 lx), tank colour (grey and black) and prey type (nauplii and a mixed diet: rotifers and nauplii) were tested, a significant difference was found only for light intensity and prey type with a significant interaction between these factors. FIC was significantly higher with nauplii stage I–III than IV–VI and also at 25 °C than at 28 °C. Green water (0, 0.3 × 106 or 1 × 106 cells mL?1) and salinity (25, 30, 35 gL?1) did not affect FIC. FIT was not affected by any variables tested except in the density experiment where it was significantly higher at 10 nauplii mL?1. 相似文献
307.
The marine environment is an important source of structurally-diverse and biologically-active secondary metabolites. During the last two decades, thousands of compounds were discovered in marine organisms, several of them having inspired the development of new classes of therapeutic agents. Marine mollusks constitute a successful phyla in the discovery of new marine natural products (MNPs). Over a 50-year period from 1963, 116 genera of mollusks contributed innumerous compounds, Aplysia being the most studied genus by MNP chemists. This genus includes 36 valid species and should be distinguished from all mollusks as it yielded numerous new natural products. Aplysia sea hares are herbivorous mollusks, which have been proven to be a rich source of secondary metabolites, mostly of dietary origin. The majority of secondary metabolites isolated from sea hares of the genus Aplysia are halogenated terpenes; however, these animals are also a source of compounds from other chemical classes, such as macrolides, sterols and alkaloids, often exhibiting cytotoxic, antibacterial, antifungal, antiviral and/or antifeedant activities. This review focuses on the diverse structural classes of secondary metabolites found in Aplysia spp., including several compounds with pronounced biological properties. 相似文献
308.
309.
Bassanezi RB Bergamin Filho A Amorim L Gimenes-Fernandes N Gottwald TR Bové JM 《Phytopathology》2003,93(4):502-512
ABSTRACT Citrus sudden death (CSD), a new disease of unknown etiology that affects sweet orange grafted on Rangpur lime, was visually monitored for 14 months in 41 groves in Brazil. Ordinary runs analysis of CSD-symptomatic trees indicated a departure from randomness of symptomatic trees status among immediately adjacent trees mainly within rows. The binomial index of dispersion (D) and the intraclass correlation (k) for various quadrat sizes suggested aggregation of CSD-symptomatic trees for almost all plots within the quadrat sizes tested. Estimated parameters of the binary form of Taylor's power law provided an overall measure of aggregation of CSD-symptomatic trees for all quadrat sizes tested. Aggregation in each plot was dependent on disease incidence. Spatial autocorrelation analysis of proximity patterns suggested that aggregation often existed among quadrats of various sizes up to three lag distances; however, significant lag positions discontinuous from main proximity patterns were rare, indicating a lack of spatial association among discrete foci. Some asymmetry was also detected for some spatial autocorrelation proximity patterns, indicating that within-row versus across-row distributions are not necessarily equivalent. These results were interpreted to mean that the cause of the disease was most likely biotic and its dissemination was common within a local area of influence that extended to approximately six trees in all directions, including adjacent trees. Where asymmetry was indicated, this area of influence was somewhat elliptical. Longer-distance patterns were not detected within the confines of the plot sizes tested. Annual rates of CSD progress based on the Gompertz model ranged from 0.37 to 2.02. Numerous similarities were found between the spatial patterns of CSD and Citrus tristeza virus (CTV) described in the literature, both in the presence of the aphid vector, Toxoptera citricida. CSD differs from CTV in that symptoms occur in sweet orange grafted on Rangpur lime. Based on the symptoms of CSD and on its spatial and temporal patterns, our hypothesis is that CSD may be caused by a similar but undescribed pathogen such as a virus and probably vectored by insects such as aphids by similar spatial processes to those affecting CTV. 相似文献
310.
A 3-yr-old male Gouldian finch (Erythrura gouldiae) died after 2 wk of lethargy, emaciation, feather loss, and abdominal distension. The bird was housed in an aviary for breeding, but it had shown loss of fertility in the previous breeding season. Necropsy revealed a gross, firm, and yellow mass involving the left testis. Histologically, the mass was a mixed form, intratubular and diffuse, Sertoli cell tumor. Some neoplastic cells had intranuclear inclusion bodies that immunoelectron microscopy proved to be polyomavirus particle aggregates. There were no viral inclusions in other tissues. The possible role of infection in the pathogenesis of the tumor is discussed. 相似文献