全文获取类型
收费全文 | 692篇 |
免费 | 48篇 |
国内免费 | 1篇 |
专业分类
林业 | 28篇 |
农学 | 16篇 |
基础科学 | 7篇 |
137篇 | |
综合类 | 39篇 |
农作物 | 45篇 |
水产渔业 | 65篇 |
畜牧兽医 | 354篇 |
园艺 | 8篇 |
植物保护 | 42篇 |
出版年
2023年 | 4篇 |
2022年 | 3篇 |
2021年 | 21篇 |
2020年 | 13篇 |
2019年 | 21篇 |
2018年 | 22篇 |
2017年 | 19篇 |
2016年 | 20篇 |
2015年 | 15篇 |
2014年 | 34篇 |
2013年 | 47篇 |
2012年 | 48篇 |
2011年 | 67篇 |
2010年 | 24篇 |
2009年 | 25篇 |
2008年 | 34篇 |
2007年 | 35篇 |
2006年 | 32篇 |
2005年 | 33篇 |
2004年 | 33篇 |
2003年 | 25篇 |
2002年 | 21篇 |
2001年 | 14篇 |
2000年 | 18篇 |
1999年 | 22篇 |
1998年 | 6篇 |
1997年 | 5篇 |
1996年 | 2篇 |
1994年 | 1篇 |
1993年 | 4篇 |
1992年 | 7篇 |
1991年 | 8篇 |
1990年 | 5篇 |
1989年 | 7篇 |
1988年 | 6篇 |
1987年 | 3篇 |
1986年 | 6篇 |
1985年 | 2篇 |
1984年 | 3篇 |
1983年 | 6篇 |
1980年 | 3篇 |
1978年 | 4篇 |
1976年 | 2篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1972年 | 1篇 |
1970年 | 2篇 |
1969年 | 2篇 |
1968年 | 1篇 |
1967年 | 1篇 |
排序方式: 共有741条查询结果,搜索用时 31 毫秒
111.
112.
Ashley B Saunders DVM Diplomate ACVIM rew S Hanzlicek DVM Elizabeth A Martinez DVM Diplomate ACVA Mark J Stickney DVM Jörg M Steiner Dr.med.vet. PhD Diplomate ACVIM Diplomate ECVIM-CA Jan S Suchodolski Dr.med.vet. PhD & Geoffery T Fosgate† DVM PhD Diplomate ACVPM 《Veterinary anaesthesia and analgesia》2009,36(5):449-456
ObjectiveTo report serum cardiac troponin I (cTnI) and C-reactive protein (CRP) concentrations in dogs anesthetized for elective surgery using two anesthetic protocols.Study designProspective, randomized clinical study.AnimalsTwenty client-owned dogs presenting for elective ovariohysterectomy or castration.MethodsThe dogs were randomized into two groups. All dogs were premedicated with glycopyrrolate (0.011 mg kg?1) and hydromorphone (0.1 mg kg?1) IM approximately 30 minutes prior to induction of anesthesia. Anesthesia in dogs in group 1 was induced with propofol (6 mg kg?1) IV to effect and in dogs in group 2 with diazepam (0.2 mg kg?1) IV followed by etomidate (2 mg kg?1) IV to effect. For maintenance of anesthesia, group 1 received sevoflurane (adjustable vaporizer setting 0.5–4%) and group 2 received a combination of fentanyl (0.8 μg kg?1 minute?1) and midazolam (8.0 μg kg?1 minute?1) IV plus sevoflurane (adjustable vaporizer setting 0.5–4%) to maintain anesthesia. Serum cTnI and CRP concentrations were measured at baseline and 6, 18, and 24 hours post-anesthetic induction. Biochemical analysis was performed at baseline. Lactate was obtained at baseline and 6 hours post-anesthetic induction. Heart rate and mean arterial blood pressure were measured intra-operatively.ResultsBaseline serum cTnI and CRP concentrations were comparable between groups. A significant difference in serum cTnI or CRP concentrations was not detected post-operatively between groups at any time point. Serum CRP concentrations were significantly increased post-anesthetic induction in both groups, which was attributed to surgical trauma.Conclusions and clinical relevanceThere was no significant difference in serum cTnI and CRP concentrations between anesthetic protocols. Further investigation in a larger number of dogs is necessary to confirm the current findings. 相似文献
113.
M. Belén García-Rodríguez M. Angeles Ríos Granja C. César Pérez García Jose M. Gonzalo Orden Maria J. Cano Rábano Inmaculada Diez Prieto 《The Canadian veterinary journal. La revue veterinaire canadienne》2009,50(9):933-935
This article describes a complex and not previously reported combination of congenital cardiac defects. Echocardiography showed dilation of right and left chambers, accompanied with patent ductus arteriosus, persistence of the left cranial vena cava, atrial septal defect (ASD), subaortic stenosis, and tricuspid dysplasia. The interatrial wall was examined and the diameter of the ASD was measured by magnetic resonance imaging (MRI). 相似文献
114.
González Canga A Sahagún Prieto AM José Diez Liébana M Martínez NF Vega MS Vieitez JJ 《Veterinary journal (London, England : 1997)》2009,179(1):25-37
The pharmacokinetic properties of drugs are closely related to their pharmacological efficacy. The kinetics of ivermectin are characterised, in general terms, by a slow absorption process, a broad distribution in the organism, low metabolism, and slow excretion. The kinetics vary according to the route of administration, formulation, animal species, body condition, age, and physiological status, all of which contribute to differences in drug efficacy. Characterisation of ivermectin kinetics can be used to predict and optimise the value of the parasiticide effects and to design programmes for parasite control. This article reviews the pharmacokinetics of ivermectin in several domestic animal species. 相似文献
115.
A new acylated quercetin glycoside and other secondary metabolites from Helleborus foetidus 总被引:1,自引:0,他引:1
A new acylated flavonol glycoside, quercetin 3-O-(2-trans-caffeoyl)-alpha-L-arabinopyranosyl-(1-->2)-beta-D-glucopyranoside (1), together with the known 25R,26-[(beta-D-glucopyranosyl)oxy]-22alpha-hydroxy-5beta-furostan-3-beta-yl O-alpha-l-rhamnopyranosyl-(1-->4)-beta-D-glucopyranoside (2), anemonin (3), beta-D-glucosyl-p-hydroxyphenylethyl alcohol (4), and 1-beta-O-caffeoyl-D-glucose (5) were isolated from Helleborus foetidus leaves and identified on the basis of detailed spectral analysis. 相似文献
116.
Blood metabolites and their relationship with production variables in dual-purpose cows in Venezuela
Parra O Ojeda A Combellas J Gabaldon L Escobar A Martinez N Benezra M 《Preventive veterinary medicine》1999,38(2-3):133-145
A survey was carried out on 79 lactating Bos taurus/indicus cross-bred cows on three dual-purpose cattle farms to measure the blood concentration of metabolites and to evaluate possible relationships with nutritional status and productive variables. A rotational grazing system on Star grass and other tropical pastures (10-12% CP in leaves) was used and 2-3 kg/cow/day of concentrate were fed on two farms. Restricted calf suckling was used in two herds. Average milk yield sold per farm was 6 kg/day/cow and body condition scores (BCS) were between 3.0 and 3.8 on a scale of one-to-five. On two farms, the average interval from calving to conception (ICC) was more than 145 days. Mean blood concentrations of albumin, globulin, urea, beta-hydroxybutyrate and phosphorus were generally within reference values, but a significant group of cows had low levels of albumin and urea and high levels of globulin. Packed cell volume (PCV) was below normal values, with anemia in 63% of cows during the second trimester of lactation, which was negatively correlated to milk yield. The high incidence of anemia could be related to factors such as hematophagic parasites, not evaluated in this study. ICC values were negatively related to albumin level and could be associated with protein deficiency in the diet or with disease, as globulin values were high in many cows. Based on these diagnoses, an experiment was carried out on one of the farms to evaluate the influence of supplementation with 0.5 kg/cow/day of fish meal. Total milk yield was not influenced by the fish meal and reproductive efficiency was high in the two supplemental treatments. It was shown that supplementation with undergraded protein is not required in these cows. 相似文献
117.
Maria D. Ayala Emilia Abellán Marta Arizcun Alicia García-Alcázar F. Navarro Alfonso Blanco Octavio M. López-Albors 《Fish physiology and biochemistry》2013,39(4):807-827
Shi drum specimens were maintained under four different photoperiod regimes: a natural photoperiod regime (16L:8D), constant light (24L), equal durations of light and dark (12L:12D) and a reduced number of daylight hours (6L:18D) from hatching until the end of larval metamorphosis. Specimens were then kept under natural photoperiod conditions until 111 days post-hatching. Muscle and body parameters were studied. During the vitelline phase, there was little muscle growth and no photoperiod effects were reported; however, a monolayer of red muscle and immature white muscle fibres were observed in the myotome. At hatching, external cells (presumptive myogenic cells) were already present on the surface of the red muscle. At the mouth opening, some presumptive myogenic cells appeared between the red and white muscles. At 20 days, new germinal areas were observed in the apical extremes of the myotome. At this stage, the 16L:8D group (followed by the 24L group) had the longest body length, the largest cross-sectional area of white muscle and the largest white muscle fibres. Conversely, white muscle hyperplasia was most pronounced in the 24L group. Metamorphosis was complete at 33 days in the 24L and 12L:12D groups. At this moment, both groups showed numerous myogenic precursors on the surface of the myotome as well as among the adult muscle fibres (mosaic hyperplastic growth). The 16L:8D group completed metamorphosis at 50 days, showing a similar degree of structural maturity in the myotome to that described in the 24L and 12L:12D groups at 33 days. When comparing muscle growth at the end of the larval period, hypertrophy was highest in the 16L:8D group, whereas hyperplasia was higher in the 24L and 16L:8D groups. At 111 days, all groups showed the adult muscle pattern typical of teleosts; however, the cross-sectional area of white muscle, white muscle fibre hyperplasia, body length and body weight were highest in the 24L group, followed by the 12L:12D group; white muscle hypertrophy was similar in all groups. Larval survival was higher under natural photoperiod conditions compared to all the other light regimes. 相似文献
118.
In autumn 2007, an allium leafminer, Phytomyza gymnostoma Loew (Diptera: Agromyzidae), was recorded for the first time in non‐commercial leek crops in the areas of Elassona and Katerini in Central Greece. Leek plants were severely damaged by the leafminer larvae infestation. Typical feeding symptoms were observed, caused by the mining behaviour of larvae within inner and outer leaves of leek plants, resulting in the formation of descending galleries. Pest control was performed locally using commercial insecticides with unknown efficacy mainly due to ignorance of the species biology. 相似文献
119.
Maria Charmela D Ates Gerald F Quinitio Emilia T Quinitio Roman C Sanares 《Aquaculture Research》2012,43(2):215-225
Morphological changes in the embryos, egg size and development, incubation period and morphological structures of newly hatched zoea of three mud crab Scylla species were determined. The three species exhibited similar embryonic development composed of 10 stages. The mean egg diameter of Scylla serrata was significantly larger (P<0.05) at the prehatch stage. The mean egg diameters of Scylla tranquebarica and Scylla olivacea were similar (P>0.05). The incubation period was the longest in S. serrata and the shortest in S. olivacea. There was a positive relationship between egg size and larval size, as S. serrata exhibited the largest egg size and first zoea. However, no correlation was detected between egg size at prehatch and lengths of the morphological structures of the newly hatched zoea. The three species exhibited similar lengths of cephalic structures, but S. olivacea had significantly shorter (P<0.05) abdominal structures. The duration of spawning from ablation was the shortest in S. tranquebarica and the longest in S. olivacea. The study is relevant to aquaculture and fisheries management of Scylla species. 相似文献
120.
The ability of the probiotic bacterium Sulfitobacter to inhibit the growth of two virulent strains (psh-9019 and ATCC 43306) of the fish pathogenic bacterium Vibrio anguillarum was tested. Probiotic and pathogenic bacteria were inoculated individually or together in three different types of media.
Two of the phytoplankton media tested were filtrates of phytoplankton Chlorella vulgaris cultures, either the live phytoplankton (live-CV) or a condensed phytoplankton (condensed-CV). Phytoplankton culture medium,
ESM, was used as a control medium without phytoplankton. In ESM, Sulfitobacter decreased the viable cell counts of both V. anguillarum strains by tenfold. In the live-CV filtrate, V. anguillarum was eradicated by Sulfitobacter within one week. Although colony counts of strain ATCC 43306 declined during the two-week co-incubation with Sulfitobacter, its growth was not fully inhibited; however, the counts were tenfold lower than that in control ESM medium. Neither of the
pathogenic V. anguillarum strains were inhibited nor eradicated by Sulfitobacter in the condensed-CV filtrate medium. Our study indicates that commercially available condensed phytoplankton can enhance
the growth of V. anguillarum. Thus, the addition of live phytoplankton, including the introduction of Roseobacter clade bacteria to fish larvae tanks, leads to better biocontrol of the fish pathogen V. anguillarum. 相似文献