全文获取类型
| 收费全文 | 584篇 |
| 免费 | 57篇 |
专业分类
| 林业 | 17篇 |
| 农学 | 11篇 |
| 61篇 | |
| 综合类 | 87篇 |
| 农作物 | 13篇 |
| 水产渔业 | 30篇 |
| 畜牧兽医 | 362篇 |
| 园艺 | 20篇 |
| 植物保护 | 40篇 |
出版年
| 2024年 | 4篇 |
| 2023年 | 11篇 |
| 2022年 | 11篇 |
| 2021年 | 31篇 |
| 2020年 | 36篇 |
| 2019年 | 21篇 |
| 2018年 | 29篇 |
| 2017年 | 23篇 |
| 2016年 | 25篇 |
| 2015年 | 17篇 |
| 2014年 | 22篇 |
| 2013年 | 22篇 |
| 2012年 | 39篇 |
| 2011年 | 59篇 |
| 2010年 | 28篇 |
| 2009年 | 18篇 |
| 2008年 | 35篇 |
| 2007年 | 42篇 |
| 2006年 | 35篇 |
| 2005年 | 28篇 |
| 2004年 | 23篇 |
| 2003年 | 17篇 |
| 2002年 | 21篇 |
| 2001年 | 3篇 |
| 2000年 | 3篇 |
| 1999年 | 3篇 |
| 1998年 | 4篇 |
| 1996年 | 2篇 |
| 1994年 | 1篇 |
| 1993年 | 1篇 |
| 1990年 | 1篇 |
| 1989年 | 1篇 |
| 1988年 | 2篇 |
| 1987年 | 1篇 |
| 1986年 | 2篇 |
| 1985年 | 1篇 |
| 1984年 | 1篇 |
| 1982年 | 1篇 |
| 1980年 | 1篇 |
| 1978年 | 1篇 |
| 1977年 | 2篇 |
| 1976年 | 1篇 |
| 1975年 | 1篇 |
| 1964年 | 1篇 |
| 1962年 | 1篇 |
| 1961年 | 1篇 |
| 1957年 | 1篇 |
| 1939年 | 1篇 |
| 1881年 | 3篇 |
| 1880年 | 1篇 |
排序方式： 共有641条查询结果，搜索用时 15 毫秒
81.
Corrin J. Boyd Melissa A. Claus Anthea L. Raisis Rachel Cianciolo Erika Bosio Giselle Hosgood Mary Nabity Trevor Mori Anne Barden Claire R. Sharp Lisa Smart 《Journal of Veterinary Emergency and Critical Care》2019,29(2):132-142
Objective : To investigate the association between synthetic colloids and biomarkers of acute kidney injury (AKI) in dogs with hemorrhagic shock. Design : Experimental interventional study. Setting : University. Animals : Twenty‐four healthy ex‐racing Greyhounds. Interventions : Anesthetized Greyhounds subjected to hemorrhage for 60 min were resuscitated with 20 mL/kg of fresh whole blood (FWB), 6% hydroxyethyl starch (HES) 130/0.4, 4% succinylated gelatin (GELO), or 80 mL/kg of isotonic crystalloid (CRYST) over 20 min (n = 6 per treatment). Concentrations of biomarkers of AKI were measured at baseline, end of hemorrhage, and at 40 (T60), 100 (T120), and 160 (T180) min after fluid bolus. Biomarkers included neutrophil gelatinase‐associated lipocalin in urine and serum (uNGAL; sNGAL), and urine cystatin C (uCYSC), kidney injury molecule‐1 (uKIM), clusterin (uCLUST), osteopontin, gamma‐glutamyl transferase, monocyte chemoattractant protein‐1 (uMCP), interleukin‐6, interleukin‐8, protein (uPROT), hyaluronan, and F2‐isoprostanes. Renal histology was scored for tubular injury and microvesiculation. Biomarker fold‐change from baseline was compared between groups using mixed effects models (Bonferroni–Holm corrected P<0.05). Frequencies of histology scores were compared by Fisher's exact test. Measurements and main results : In dogs treated with GELO, uNGAL fold‐change was markedly greater compared with all other groups at T60, T120, and T180 (all P<0.001), and uCYSC was greater at T60 compared with CRYST (P<0.001), and at T120 and T180 compared with all other groups (all P<0.001). Smaller, albeit significant, between‐group differences in uKIM, uCLUST, uMCP, and urine protein concentration were observed across the FWB, GELO, and HES groups, compared with CRYST. The GELO group more frequently had marked tubular microvesiculation than the other groups (P = 0.015) although tubular injury scores were comparable. Conclusion : In dogs with hemorrhagic shock, GELO was associated with greater magnitude increases in urine biomarkers of AKI and more frequent marked tubular microvesiculation, compared with FWB, CRYST, and HES. 相似文献
82.
83.
Dean RS Helps CR Gruffydd Jones TJ Tasker S 《Journal of Feline Medicine and Surgery》2008,10(4):413-417
Feline haemoplasma infection can cause haemolytic anaemia. The natural method of transmission of haemoplasmas between cats is currently unknown but the nature of some of the risk factors for infection suggests that saliva may act as a mode of transmission. The aim of this study was to determine if Mycoplasma haemofelis (Mhf) and 'Candidatus Mycoplasma haemominutum' (CMhm) DNAs could be amplified from saliva and salivary gland samples collected from haemoplasma-infected cats. 相似文献
84.
85.
86.
87.
Andrew G. Merschel Emily K. Heyerdahl Thomas A. Spies Rachel A. Loehman 《Landscape Ecology》2018,33(7):1195-1209
Context
In the interior Northwest, debate over restoring mixed-conifer forests after a century of fire exclusion is hampered by poor understanding of the pattern and causes of spatial variation in historical fire regimes.Objectives
To identify the roles of topography, landscape structure, and forest type in driving spatial variation in historical fire regimes in mixed-conifer forests of central Oregon.Methods
We used tree rings to reconstruct multicentury fire and forest histories at 105 plots over 10,393 ha. We classified fire regimes into four types and assessed whether they varied with topography, the location of fuel-limited pumice basins that inhibit fire spread, and an updated classification of forest type.Results
We identified four fire-regime types and six forest types. Although surface fires were frequent and often extensive, severe fires were rare in all four types. Fire regimes varied with some aspects of topography (elevation), but not others (slope or aspect) and with the distribution of pumice basins. Fire regimes did not strictly co-vary with mixed-conifer forest types.Conclusions
Our work reveals the persistent influence of landscape structure on spatial variation in historical fire regimes and can help inform discussions about appropriate restoration of fire-excluded forests in the interior Northwest. Where the goal is to restore historical fire regimes at landscape scales, managers may want to consider the influence of topoedaphic and vegetation patch types that could affect fire spread and ignition frequency.88.
Rachel E. Marschang Karola Weider Hanna Erhard Eva-Maria Klas Claudia Laik-Schandelmaier 《Journal of Exotic Pet Medicine》2018,27(4):27-30
Rabbit hemorrhagic disease (RHD) is an important cause of disease and mortality in wild and domestic European rabbits (Oryctolagus cuniculus) throughout the world. Testing for 2 distinct RHD virus types (RHDV/RHDVa and RHDV2) was carried out on samples collected from 684 rabbits submitted from veterinary practices and private owners throughout Europe between January 2015 and June 2017. Four (0.6%) were positive for RHDV/RHDVa and 257 (37.4%) were positive for RHDV2. RHDV/RHDVa was detected in individual samples from Germany and the Netherlands, while RHDV2 was found in animals from Germany, Great Britain, Luxembourg, The Netherlands, Spain, Switzerland, Poland, Belgium, Austria, Sweden, and Finland. 相似文献
89.
Context
Anthropogenic landscape simplification and natural habitat loss can negatively affect wild bees. Alternatively, anthropogenic land-use change may diversify landscapes, creating complementary habitats that maintain overall resource continuity and diversity.Objectives
We examined the effects of landscape composition, including land-cover diversity and percent semi-natural habitat, on wild bee abundance and species richness within apples, a pollinator-dependent crop. We also explored whether different habitats within diverse landscapes can provide complementary floral resources for bees across space and time.Methods
We sampled bees during apple bloom over 2 years within 35 orchards varying in surrounding landscape diversity and percent woodland (the dominant semi-natural habitat) at 1 km radii. To assess habitat complementarity in resource diversity and temporal continuity, we sampled flowers and bees within four unique habitats, including orchards, woodlands, semi-natural grasslands, and annual croplands, over three periods from April–June.Results
Surrounding landscape diversity positively affected both wild bee abundance and richness within orchards during bloom. Habitats in diverse landscapes had different flower communities with varying phenologies; flowers were most abundant within orchards and woodlands in mid-spring, but then declined over time, while flowers within grasslands marginally increased throughout spring. Furthermore, bee communities were significantly different between the closed-canopy habitats, orchards and woodlands, and the open habitats, grasslands and annual croplands.Conclusions
Our results suggest that diverse landscapes, such as ones with both open (grassland) and closed (woodland) semi-natural habitats, support spring wild bees by providing flowers throughout the entire foraging period and diverse niches to meet different species’ requirements.90.
Growth and Mineral Absorption by Striped Bass Morone saxatilis Fed a Plant Feedstuff Based Diet Supplemented with Phytase 总被引：3，自引：0，他引：3
Elias Papatryphon Rachel A. Howell Joseph H. Soares Jr. 《Journal of the World Aquaculture Society》1999,30(2):161-173
Two experiments were conducted to determine the effects of phytase on growth, apparent phosphorus (P), calcium (Ca), iron (Fe), zinc (Zn), magnesium (Mg), and copper (Cu) absorption, and apparent protein digestibility by striped bass Morone saxatills fed a high phytate diet. In experiment one, four diets with graded levels of phytase supplementation, 0, 500, 1,000, and 2,000 phytase units/kg of diet (PUkg), and a diet supplemented with inorganic P (positive control, total P, 0.73%; phytin P, 0.35%) were assigned to duplicate tanks, and were fed to fingerling striped bass for 16 wk. A digestibility trial was conducted at weeks 16–18, using 0.5% Cr2O3 as an indigestible marker in the diets. Phytase was sprayed post-extrusion on the basal diet (P-total, 0.58%; P-phytin, 0.35%). Experiment two consisted of a 2-wk digestibility trial with three treatments: 0 (basal; total P, 0.73%; phytin P, 0.34%), 1,000, and 2,000 PU/kg, assigned to four, three and three replicate tanks respectively. Each tank contained an average of 20 striped bass (mean weight: 400 9). The diet used was similar to the basal in experiment one, which was modified to have low essential trace mineral concentrations, in order to increase the sensitivity of the assay. In experiment one, significant improvements (P≤ 0.05) in growth, feed conversion ratios, and vertebral and scale ash concentrations of fish at the end of the experiment were achieved with either added inorganic P or increasing phytase supplementations. Results from both digestibility trials indicated that P absorption was improved with the addition of at least 500 PUkg. Absorptions of Ca and Fe were significantly increased (P≤ 0.05) and Zn absorption marginally improved (P≤ 0.06) when at least 2,000 PU/kg was supplemented to the diet. Protein digestibility, Mg and Cu absorption were not significantly different in any treatment. Whole carcass P retention was significantly improved with the addition of 1,000 PU/kg, and 2,000 PU/kg, when compared to fish fed the basal diet, 500 PU/kg and positive control treatments. Results from these experiments indicate that phytase supplementation of at least 1,000 PU/kg is adequate to maintain growth rate and health comparable to an inorganic P supplemented diet. In addition, bioavailability and utilization of P is increased with increasing phytase supplementation. Diet supplementation of 2,000 PU/kg increased Ca, Fe, and Zn digestibility by striped bass fed a high phytate diet. 相似文献