全文获取类型
收费全文 | 1125篇 |
免费 | 59篇 |
国内免费 | 1篇 |
专业分类
林业 | 38篇 |
农学 | 24篇 |
基础科学 | 6篇 |
192篇 | |
综合类 | 207篇 |
农作物 | 35篇 |
水产渔业 | 46篇 |
畜牧兽医 | 524篇 |
园艺 | 54篇 |
植物保护 | 59篇 |
出版年
2024年 | 2篇 |
2023年 | 11篇 |
2022年 | 7篇 |
2021年 | 19篇 |
2020年 | 21篇 |
2019年 | 25篇 |
2018年 | 28篇 |
2017年 | 20篇 |
2016年 | 28篇 |
2015年 | 17篇 |
2014年 | 44篇 |
2013年 | 60篇 |
2012年 | 66篇 |
2011年 | 102篇 |
2010年 | 45篇 |
2009年 | 37篇 |
2008年 | 80篇 |
2007年 | 60篇 |
2006年 | 63篇 |
2005年 | 80篇 |
2004年 | 78篇 |
2003年 | 56篇 |
2002年 | 68篇 |
2001年 | 15篇 |
2000年 | 13篇 |
1999年 | 6篇 |
1998年 | 8篇 |
1997年 | 9篇 |
1996年 | 5篇 |
1995年 | 10篇 |
1994年 | 12篇 |
1993年 | 6篇 |
1992年 | 9篇 |
1991年 | 6篇 |
1990年 | 7篇 |
1989年 | 8篇 |
1987年 | 5篇 |
1986年 | 2篇 |
1985年 | 5篇 |
1984年 | 3篇 |
1983年 | 4篇 |
1982年 | 4篇 |
1981年 | 4篇 |
1980年 | 4篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1972年 | 2篇 |
1967年 | 2篇 |
1966年 | 3篇 |
1935年 | 1篇 |
排序方式: 共有1185条查询结果,搜索用时 15 毫秒
991.
992.
993.
Natalie D Mylniczenko Karen S Kearns Ann C Melli 《Journal of zoo and wildlife medicine》2008,39(2):228-235
A captive harbor seal (Phoca vitulina) presented with partial anorexia, ataxia, and head bobbing, which progressed to complete anorexia, lethargy, and persistent whole-body intention tremors within several days. Response to treatment with ponazuril, serology, and cerebrospinal fluid analysis supported a diagnosis of Sarcocystis neurona. Analysis of serum levels for ponazuril indicated that therapeutic levels could be achieved at a dosage of 5 mg/kg p.o. s.i.d., whereas clinical response was improved at a dosage of 10 mg/kg. Several months after initiation of antiprotozoal therapy, the neurologic signs resolved, although rare intermittent tremors were seen with significant exertion. 相似文献
994.
Amy L. Butler DVM MS Vicki L. Campbell DVM DACVA DACVECC Ann E. Wagner DVM DACVA DACVP Cassidy D. Sedacca DVM Timothy B. Hackett DVM MS DACVECC 《Journal of Veterinary Emergency and Critical Care》2008,18(3):246-257
Objective: Compare cardiac index (CI) and oxygen delivery index (DO2I) in conscious, critically ill dogs to control dogs; evaluate the association of CI and DO2I with outcome. Design: Prospective non‐randomized clinical study. Setting: Veterinary teaching hospital. Animals: Eighteen client‐owned dogs with systemic inflammatory response syndrome (SIRS) and 8 healthy control dogs. Measurements and Main Results: CI of dogs with SIRS was measured using lithium dilution at times 0, 4, 8, 16, and 24 hours. Data collected included physical exam, arterial blood gas (ABG) and hemoximetry. CI of control dogs was measured 3 times with 1 measurement of ABG. Mean CI ± SE in SIRS patients was 3.32 ± 0.95 L/min/m2; lower than controls at 4.18 ± 0.22 L/min/m2 (P<0.001). Mean DO2I ± SE in SIRS patients was 412.91 ± 156.67 mL O2/min/m2; lower than controls at 785.24 ± 45.99 mL O2/min/m2 (P<0.001). There was no difference in CI (P=0.49) or DO2I (P=0.51) for dogs that survived to discharge versus those that did not. There was no difference in mean CI (P=0.97) or DO2I (P=0.50) of survivors versus non‐survivors for 28‐day survival. Survivors had lower blood glucose (P=0.03) and serum lactate concentrations (P=0.04) than non‐survivors. Conclusions: CI and DO2I in conscious dogs with SIRS were lower than control dogs, which differs from theories that dogs with SIRS are in a high cardiac output state. CI and DO2I were not significantly different between survivors and non‐survivors. Similar to previous studies, lactate and glucose concentrations of survivors were lower than non‐survivors. 相似文献
995.
996.
Mayha Mohammed Ali Nor Elmadiena Adil Ali El Hussein Catherine Anne Muckle Linda Cole Elizabeth Wilkie Ketna Mistry Ann Perets 《Tropical animal health and production》2013,45(5):1113-1118
This study was undertaken to determine the antimicrobial resistance patterns of Salmonella enterica subspecies enterica recovered from human, food, water, and animal samples collected in Khartoum State, Sudan. A total of 64 Salmonella isolates belonging to 28 different serovars were tested for their susceptibility to 13 antimicrobial agents. The majority of isolates (98.4 %) were resistant to at least one antimicrobial agent. Isolates were frequently resistant to ampicillin (90.6 %), cephalexin (50.0 %), nalidixic acid (25.0 %), streptomycin (21.9 %), kanamycin (18.8 %), gentamicin (17.2 %), and co-trimoxazole and trimethoprim (12.5 %). The most common pattern of multiple drug resistance included resistance to ampicillin and cephalexin. Most isolates were sensitive to chloramphenicol (98.4 %), ciprofloxacin (93.8 %), and norfloxacin (90.6 %). Two chicken- and the two human-origin S. Kentucky isolates were resistant to both ciprofloxacin and norfloxacin. All S. Kentucky isolates and the one S. Rissen isolate demonstrated multi-drug resistance. The results indicate the significance of multi-drug-resistant Salmonella serovars isolated from chickens and other animals and foods as sources for multi-drug-resistant Salmonella in humans in Sudan. 相似文献
997.
Mari Espetvedt Ann-Kristina Lind Cecilia Wolff Simo Rintakoski Anna-Maija Virtala Ann Lindberg 《Preventive veterinary medicine》2013,108(2-3):114-124
Previous studies have addressed the differences in registered disease incidence between the Nordic dairy disease recording systems. The main objective of this study was to investigate whether Nordic dairy farmers have varying intention to contact a veterinarian the same day as detecting signs of mild clinical mastitis (MCM) in a lactating dairy cow. This is the first, and necessary, step in the process leading to a disease event being recorded. The second objective was to study underlying behavioural components influencing this threshold for action.A questionnaire-based survey was carried out in Denmark, Finland, Norway and Sweden. The questionnaire was based on the Theory of Planned Behaviour from the field of social psychology. After performing qualitative face-to-face elicitation interviews a set of statements about treatment of MCM was identified. These were grouped into behavioural, normative and control beliefs. The most frequently mentioned beliefs were rephrased as questions. Behavioural intention, a proxy for the behaviour of interest, was assessed using case scenarios. The target and eligible herds were in milk recording and had an average herd size of at least 15 cows. The questionnaire was distributed to 400 randomly sampled dairy producers per included country. The response rate was around 50% in all four countries.The hypothesis of differences in behavioural intention between the countries was tested using Wilcoxon's rank-sum tests. Multivariable linear regression was used to estimate the country-specific variability in behavioural intention as explained by attitude, subjective norm or perceived behavioural control alone, or in combination. The Spearman rank correlations between behavioural intention and each belief, weighted by its outcome evaluation or the motivation to comply, were estimated to find the most important drivers, constraints and social referents for the behaviour of interest.There were significant (p < 0.01) differences in behavioural intention between all countries except Denmark and Norway. Swedish farmers had the weakest behavioural intention and Finnish farmers the strongest. Attitude explained most of the variability in behavioural intention in all four countries. The most important driver in all countries was to achieve a quick recovery for the cow.The varying behavioural intention partly explain the differences in completeness of disease data in the Nordic countries: if farmers have different thresholds for contacting a veterinarian the registered incidence of clinical mastitis will be affected. Knowledge about the importance of attitudes and specific drivers may be useful in any communication about mastitis management in the Nordic countries. 相似文献
998.
Landscape supplementation in adjacent savannas and its implications for the design of corridors for forest birds in the central Cerrado, Brazil 总被引:1,自引:0,他引:1
We examined landscape supplementation (sensu [Oikos 65 (1992) 169]) by forest birds along forest/savanna boundaries in central Brazil to: (1) verify the role of savanna vegetation in providing resources to forest bird communities; (2) suggest minimum amounts of savannas to be conserved within corridors, to provide adequate foraging habitat for forest birds outside reserves. Transect counts parallel (n=64) and perpendicular (n=64) to forests were conducted in eight savannas (cerrado sensu stricto) between February 2000 and January 2001. Patterns of species richness and abundance of birds in relation to distances from forests were examined using Generalised Linear Mixed Models. Omnivores were the most abundant birds foraging in savannas, followed by insectivores and frugivores. Landscape supplementation in savannas was proportional to the density of savanna vegetation. Also, it was higher in the breeding season than in the non-breeding period. These two patterns suggest that surrounding savannas play a major role in providing additional foraging areas for forest bird species. We suggest that the environmental policy currently protecting 20 m of gallery forests along each side of rivers be modified to include at least 60 m of savanna along these forests through central Brazil. The study suggests that appropriate conservation efforts should also encompass the surrounding matrix to which the home ranges of target species are expanded, and not only their major habitat. 相似文献
999.
Fullerene pipes 总被引:10,自引:0,他引:10
J Liu AG Rinzler H Dai JH Hafner RK Bradley PJ Boul A Lu T Iverson K Shelimov CB Huffman F Rodriguez-Macias YS Shon TR Lee DT Colbert RE Smalley 《Science (New York, N.Y.)》1998,280(5367):1253-1256
Single-wall fullerene nanotubes were converted from nearly endless, highly tangled ropes into short, open-ended pipes that behave as individual macromolecules. Raw nanotube material was purified in large batches, and the ropes were cut into 100- to 300-nanometer lengths. The resulting pieces formed a stable colloidal suspension in water with the help of surfactants. These suspensions permit a variety of manipulations, such as sorting by length, derivatization, and tethering to gold surfaces. 相似文献
1000.
Nicolas I Busse Madison L Gonzalez Mackenzie L Krason Sally E Johnson 《Journal of animal science》2021,99(10)
Consumption of β-hydroxy β-methylbutyrate (HMB) alters muscle composition and metabolism leading to strength and agility improvements in human athletes. To determine if HMB affects athletic performance and muscle function in horses, Thoroughbred geldings were fed a control (CON; n = 5) or HMB (n = 6) supplement for 6 wk prior to completing a standardized exercise test (SET). Gluteus medius (GM) muscle biopsies were obtained before the SET for fiber typing. Heart rate, biceps femoris (BF) and semitendinosus (ST) surface electromyograms (EMG), and fore and hind limbs metacarpophalangeal joint angles were captured at the gallop of the SET. Results demonstrate that HMB supplementation increased (P < 0.05) the percentage of type IIA and IIA/X muscle fibers in the GM with a corresponding decrease (P < 0.05) in type IIX fibers. The percentage of type I fibers was unaffected by diet. Supplementation with HMB did not result in any measurable effects on performance or biomechanical properties by comparison to CON. Supplementation with HMB resulted in an increase (P < 0.05) in ST median frequency at speeds of 10 m/s and greater. Increasing treadmill speed resulted in an increase (P < 0.05) in stride length and the maximal proximal forelimb fetlock angle, and a decrease (P < 0.05) in stance phase time of the gait cycle. Integrated EMG (iEMG) increased (P < 0.05) with increasing treadmill speeds for both the BF and ST with the BF exhibiting greater (P < 0.05) iEMG values than the ST. In summary, HMB increased the percentage of type IIA GM fibers, which did not translate into improved performance. 相似文献