全文获取类型
收费全文 | 214篇 |
免费 | 18篇 |
专业分类
林业 | 2篇 |
农学 | 2篇 |
综合类 | 22篇 |
农作物 | 3篇 |
水产渔业 | 43篇 |
畜牧兽医 | 152篇 |
植物保护 | 8篇 |
出版年
2023年 | 4篇 |
2020年 | 4篇 |
2019年 | 7篇 |
2018年 | 9篇 |
2017年 | 4篇 |
2016年 | 3篇 |
2015年 | 4篇 |
2013年 | 12篇 |
2012年 | 8篇 |
2011年 | 3篇 |
2010年 | 13篇 |
2009年 | 6篇 |
2008年 | 4篇 |
2007年 | 5篇 |
2006年 | 2篇 |
2005年 | 8篇 |
2004年 | 3篇 |
2002年 | 2篇 |
2001年 | 1篇 |
2000年 | 1篇 |
1999年 | 7篇 |
1998年 | 15篇 |
1997年 | 11篇 |
1996年 | 13篇 |
1995年 | 12篇 |
1994年 | 6篇 |
1993年 | 4篇 |
1992年 | 5篇 |
1991年 | 6篇 |
1990年 | 7篇 |
1989年 | 6篇 |
1988年 | 1篇 |
1987年 | 4篇 |
1986年 | 1篇 |
1985年 | 3篇 |
1984年 | 2篇 |
1982年 | 2篇 |
1981年 | 2篇 |
1980年 | 6篇 |
1979年 | 2篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1975年 | 1篇 |
1971年 | 2篇 |
1966年 | 1篇 |
1964年 | 1篇 |
1961年 | 1篇 |
1944年 | 1篇 |
1929年 | 2篇 |
1928年 | 1篇 |
排序方式: 共有232条查询结果,搜索用时 0 毫秒
51.
Abstract This study on reef placement involves two aspects: (1) the development of a bioenergetics model for red snapper, Lutjanus campechanus (Poey), in Gulf of Mexico waters off the coast of Alabama, where significant numbers of artificial reefs are thought to exist, and (2) a fuzzy rough set model by which parameters determined from the bioenergetics model can provide a decision tool for optimally spacing artificial reefs during deployment. The bioenergetics and consumption rates of L. campechanus by age class foraging on artificial reefs in the Gulf of Mexico off the coast of Alabama provided input into the fuzzy rule‐based model. After conducting multiple simulations, highest certainty in optimal reef spacing was achieved for reef distances between 0.50 and 0.95 km such that no more than two fit within a 1‐km2 area. Results can inform fisheries managers about placement of artificial reefs to affect the health and survival of reef‐associated species. 相似文献
52.
Résumé— Un épithélioma spinocellulaire s'est développé sur des lésions chroniques incontrôlées de lupus erythémateux discoïde chez deux chiens bergers allemands. Les chiens n'avaient reçu ni traitement ni photoprotection pour leurs lésions de lupus discoïde durant les 4 à 6 ans précédant l'apparition clinique d'épithéliomas spinocellulaires. [Scott, D.W., Miller, W.H., Jr. Squamous cell carcinoma arising in chronic discoid lupus erythematosus nasal lesions in two German Shepherd Dogs (Un épithélioma spinocellulaire suivenant sur des lesions de lupus erythémateux discoïde chroniques chez deux bergers allemands).
Resumen— Dos perros de raza Pastor Alemán desarrollaron carcinomas de células escamosas en lesiones crónicas del tipo lupus eritematoso discoide. Estos animales no habian recibido tratamiento ni protección solar del cuadro de lupus eritematoso discoide en los 4 a 6 años previos al desarrollo del carcinoma escamoso. [Scott, D.W., Miller, W.H., Jr. Squamous cell carcinoma arising in chronic discoid lupus erythematosus nasal lesions in two German Shepherd Dogs (Carcinoma de células escamosas a partir de lesiones crónicas nasales del tipo lupus eritematoso discoide en dos perros Pastor Alemán).
Abstract— Squamous cell carcinoma developed in the chronic, uncontrolled nasal lesions of discoid lupus erythematosus in two German Shepherd Dogs. The dogs had received no treatment nor photoprotection for their discoid lupus erythematosus for 4–6 years prior to the clinical onset of squamous cell carcinoma. 相似文献
Resumen— Dos perros de raza Pastor Alemán desarrollaron carcinomas de células escamosas en lesiones crónicas del tipo lupus eritematoso discoide. Estos animales no habian recibido tratamiento ni protección solar del cuadro de lupus eritematoso discoide en los 4 a 6 años previos al desarrollo del carcinoma escamoso. [Scott, D.W., Miller, W.H., Jr. Squamous cell carcinoma arising in chronic discoid lupus erythematosus nasal lesions in two German Shepherd Dogs (Carcinoma de células escamosas a partir de lesiones crónicas nasales del tipo lupus eritematoso discoide en dos perros Pastor Alemán).
Abstract— Squamous cell carcinoma developed in the chronic, uncontrolled nasal lesions of discoid lupus erythematosus in two German Shepherd Dogs. The dogs had received no treatment nor photoprotection for their discoid lupus erythematosus for 4–6 years prior to the clinical onset of squamous cell carcinoma. 相似文献
53.
LY Hardefeldt JR Gilkerson H Billman‐Jacobe MA Stevenson K Thursky KE Bailey 《Australian veterinary journal》2018,96(5):151-154
Antimicrobial resistance is a public health emergency, placing veterinary antimicrobial use under growing scrutiny. Antimicrobial stewardship, through appropriate use of antimicrobials, is a response to this threat. The need for antimicrobial stewardship in Australian veterinary practices has had limited investigation. A 2016 survey undertaken to investigate antimicrobial usage patterns by Australian veterinarians found that antimicrobial dose rates were varied and often inappropriate. Doses of procaine penicillin in horses and cattle were often low, with 68% and 90% of respondents, respectively, reporting doses that were unlikely to result in plasma concentrations above minimum inhibitory concentrations for common equine and bovine pathogens. Frequency of penicillin administration was also often inappropriate. Gentamicin doses in horses were largely appropriate (89% of dose rates appropriate), but 9% of respondents reported twice daily dosing. Amoxycillin and amoxycillin‐clavulanate were administered at the appropriate doses, or above, to dogs and cats by 54% and 70% of respondents, respectively. Here, we explore the potential reasons for inappropriate antimicrobial dose regimens and report that antimicrobial labels often recommend incorrect dose rates and thus may be contributing to poor prescribing practices. Changes to legislation are needed to ensure that antimicrobial drug labels are regularly updated to reflect the dose needed to effectively and safely treat common veterinary pathogens. This will be especially true if changes in legislation restrict antimicrobial use by veterinarians to the uses and doses specified on the label, thus hampering the current momentum towards improved antimicrobial stewardship. 相似文献
54.
DO Gough AG Kosovichev J Toomre E Anderson HM Antia S Basu B Chaboyer SM Chitre J Christensen-Dalsgaard WA Dziembowski A Eff-Darwich JR Elliott PM Giles PR Goode JA Guzik JW Harvey F Hill JW Leibacher MJPFG Monteiro O Richard T Sekii H Shibahashi M Takata MJ Thompson S Vauclair SV Vorontsov 《Science (New York, N.Y.)》1996,272(5266):1296-1300
Global Oscillation Network Group data reveal that the internal structure of the sun can be well represented by a calibrated standard model. However, immediately beneath the convection zone and at the edge of the energy-generating core, the sound-speed variation is somewhat smoother in the sun than it is in the model. This could be a consequence of chemical inhomogeneity that is too severe in the model, perhaps owing to inaccurate modeling of gravitational settling or to neglected macroscopic motion that may be present in the sun. Accurate knowledge of the sun's structure enables inferences to be made about the physics that controls the sun; for example, through the opacity, the equation of state, or wave motion. Those inferences can then be used elsewhere in astrophysics. 相似文献
55.
56.
The structure of the upper atmosphere of mars: In situ accelerometer measurements from mars global surveyor 总被引:1,自引:0,他引:1
GM Keating SW Bougher RW Zurek RH Tolson GJ Cancro SN Noll JS Parker TJ Schellenberg RW Shane BL Wilkerson JR Murphy JL Hollingsworth RM Haberle M Joshi JC Pearl BJ Conrath MD Smith RT Clancy RC Blanchard RG Wilmoth DF Rault TZ Martin DT Lyons PB Esposito MD Johnston al et 《Science (New York, N.Y.)》1998,279(5357):1672-1676
The Mars Global Surveyor (MGS) z-axis accelerometer has obtained over 200 vertical structures of thermospheric density, temperature, and pressure, ranging from 110 to 170 kilometers, compared to only three previous such vertical structures. In November 1997, a regional dust storm in the Southern Hemisphere triggered an unexpectedly large thermospheric response at mid-northern latitudes, increasing the altitude of thermospheric pressure surfaces there by as much as 8 kilometers and indicating a strong global thermospheric response to a regional dust storm. Throughout the MGS mission, thermospheric density bulges have been detected on opposite sides of the planet near 90 degreesE and 90 degreesW, in the vicinity of maximum terrain heights. This wave 2 pattern may be caused by topographically-forced planetary waves propagating up from the lower atmosphere. 相似文献
57.
The presence or absence of motorized boats, partnerships and multispecies catches characterize the fisheries of São Francisco River, Minas Gerais, Brazil. Fishing activity based on 109 interviews, carried out in the wet (high water: February and March) and dry (low water: July and August) seasons, with professional fishermen are described. Aiming to identify the fishery income components, a covariance model was proposed, with the income as the response variable, related to the factors: fishing ground; use of motorized or paddle boat; seasonality; presence of fishing assistant; and the following covariates: capture in weight in the week prior to the interview; fisherman experience in yrs; and distance (km) travelled for fishing. The results indicated that the main contributions to income were the absence of an engine (because of high price of the fuel), the absence of a partner (because of low capture) and the amount of fish caught by the fishermen. 相似文献
58.
59.
DAVID M. CHECKLEY JR MARISA N.C. LITZ RICHARD D. BRODEUR WILLIAM T. PETERSON 《Fisheries Oceanography》2012,21(6):393-404
We examined variability in growth rate during the larval stage of northern anchovy (Engraulis mordax) in response to physical and biological environmental factors in 2005 and 2006. The onset of spring upwelling was anomalously delayed by 2–3 months until mid‐July in 2005; in contrast, spring upwelling in 2006 began as a normal year in the northern California Current. Larval and early juvenile E. mordax were collected in August, September, and October off the coast of Oregon and Washington. Hatch dates ranged from May to September, with peaks in June and August in 2005 and a peak in July in 2006, based on the number of otolith daily increments. Back‐calculated body length‐at‐age in the June 2005 hatch cohort was significantly smaller than in the August 2005 cohort, which had comparable growth to the July 2006 cohort. Standardized otolith daily increment widths as a proxy for seasonal variability in somatic growth rates in 2005 were negative until late July and then changed to positive with intensification of upwelling. The standardized increment width was a positive function of biomass of chlorophyll a concentration, and neritic cold‐water and oceanic subarctic copepod species sampled biweekly off Newport, Oregon. Our results suggest that delayed upwelling in 2005 resulted in low food availability and, consequently, reduced E. mordax larval growth rate in early summer, but once upwelling began in July, high food availability enhanced larval growth rate to that typical of a normal upwelling year (e.g., 2006) in the northern California Current. 相似文献
60.
JR Delaney DS Kelley MD Lilley DA Butterfield JA Baross WSD Wilcock RW Embley M Summit 《Science (New York, N.Y.)》1998,281(5374):222-230
Seafloor diking-eruptive events represent the irreducible, quantum events of upper oceanic crustal accretion. They record events by which a large portion of the oceanic crust has formed through geological history. Since 1993, the U.S. Navy's real-time Sound Surveillance System has allowed location of ongoing acoustic signatures of dike emplacement and basalt eruptions at ridge crests in the northeast Pacific. These diking-eruptive events trigger a sequence of related, rapidly evolving physical, chemical, and biological processes. Magmatic volatiles released during these events may provide nutrients for communities of subseafloor microorganisms, some of which thrive in high-temperature anaerobic environments. Many of the organisms identified from these systems are Archaea. If microorganisms can thrive in the water-saturated pores and cracks within deep, volcanically active portions of our planet, other hydrothermally active planets may harbor similar life forms. 相似文献