全文获取类型
收费全文 | 519篇 |
免费 | 19篇 |
专业分类
林业 | 11篇 |
农学 | 14篇 |
基础科学 | 7篇 |
75篇 | |
综合类 | 128篇 |
农作物 | 14篇 |
水产渔业 | 37篇 |
畜牧兽医 | 232篇 |
园艺 | 4篇 |
植物保护 | 16篇 |
出版年
2022年 | 5篇 |
2021年 | 4篇 |
2020年 | 4篇 |
2019年 | 5篇 |
2017年 | 8篇 |
2016年 | 7篇 |
2015年 | 10篇 |
2014年 | 12篇 |
2013年 | 19篇 |
2012年 | 11篇 |
2011年 | 29篇 |
2010年 | 12篇 |
2009年 | 16篇 |
2008年 | 20篇 |
2007年 | 19篇 |
2006年 | 18篇 |
2005年 | 15篇 |
2004年 | 9篇 |
2003年 | 13篇 |
2002年 | 15篇 |
2001年 | 13篇 |
2000年 | 12篇 |
1999年 | 9篇 |
1998年 | 8篇 |
1997年 | 9篇 |
1996年 | 4篇 |
1995年 | 5篇 |
1992年 | 9篇 |
1991年 | 13篇 |
1990年 | 12篇 |
1989年 | 14篇 |
1988年 | 5篇 |
1987年 | 6篇 |
1986年 | 6篇 |
1985年 | 8篇 |
1983年 | 9篇 |
1979年 | 8篇 |
1978年 | 7篇 |
1977年 | 8篇 |
1974年 | 4篇 |
1971年 | 3篇 |
1970年 | 3篇 |
1969年 | 3篇 |
1967年 | 5篇 |
1965年 | 3篇 |
1945年 | 3篇 |
1915年 | 6篇 |
1912年 | 4篇 |
1910年 | 3篇 |
1890年 | 5篇 |
排序方式: 共有538条查询结果,搜索用时 15 毫秒
1.
Abstract. The histological features of the disease caused by infection of turbot by Herpesvirus scophthalmi are described. Infection of epidermal cells of skin and gill resulted in the formation of giant cells showing a variety of nuclear and cytoplasmic changes associated with the replication of the virus. The effects of the condition together with possible control measures are discussed. 相似文献
2.
In September 1991 cataracts occurred in two year-classes of triploid Atlantic salmon. The fish showed varying degrees of blindness, were lethargic and became emaciated owing to their inability to feed. The lesions in the lens were mainly in the anterior and posterior cortex and perinuclear areas, the capsule and embryonic nucleus remaining unaffected. Diploid fish of the same year-class did not have cataracts. The origin of the triploid fish, the method of triploidisation, their diet and disease status were investigated, but no predisposing factors could be found to account for the high incidence of cataracts. 相似文献
3.
Blood bactericidal assay (Pasteurella haemolytica) comparison of morbidity in marketed feeder calves 总被引:2,自引:0,他引:2
An in vitro bactericidal assay that used bovine heparinized blood was investigated for its usefulness in detecting differences in the bactericidal immunity of calves against Pasteurella haemolytica serotype 1 (Ph1). Greater than 90% of killing occurred within 30 minutes. The substitution of fetal calf serum for autologous calf plasma caused loss of bactericidal activity of the blood. Decomplemented calf serum also was low in bactericidal activity. The blood bactericidal assay appears to be opsonin antibody-dependent and complement-dependent. The coefficient of variation (CV) that can be expected with this assay was established by use of a group of 8 calves; within-day CV maximum was 0.9, and between-day CV maximum was 2.1. The blood bactericidal assay was used to evaluate 30 calves under typical market stress from 4 farms in eastern Tennessee. All calves had decreased bactericidal activity, as they moved into a feedyard in Texas. The bactericidal activity was reduced among sick calves, based on the severity of clinical signs. Morbidity was highest during the first 14 days in the feedlot. During this period, healthy calves had a decreased bactericidal index (BI) of 4 points, and calves with clinical signs of bovine respiratory tract disease for 3 days had a decreased BI of 8 points. The average reduction in the BI of calves with clinical signs of bovine respiratory tract disease for 6 or more days was 14 points. 相似文献
4.
Richards JR Elston TH Ford RB Gaskell RM Hartmann K Hurley KF Lappin MR Levy JK Rodan I Scherk M Schultz RD Sparkes AH 《Journal of the American Veterinary Medical Association》2006,229(9):1405-1441
Vaccination is a medical procedure, and the decision to vaccinate should be based on a risk-based assessment for each cat and each vaccine. 相似文献
5.
The 1998 Report of the American Association of Feline Practitioners and Academy of Feline Medicine Advisory Panel on Feline Vaccines was developed to help veterinary practitioners formulate vaccination protocols for cats. The current panel report updates information, addresses questions, and speaks to concerns raised by the 1998 report. In addition it reviews vaccine licensing, labeling, and liability issues and suggests ways to successfully incorporate vaccination protocol changes into a private practice setting. 相似文献
6.
J. I. Richards 《Tropical animal health and production》1985,17(4):209-217
Summary Four primiparous Friesian cows in mid-lactation and housed in climate chambers were simultaneously exposed to three sequential
climate treatments: 1, a three-week period in a thermoneutral environment (ambient temperatureT
a
14–21°C and relative humidity r.h. 60–70%); 2, a similar period during which they were exposed toT
a
max. 38°C/r.h. max. 80% for up to 7h andT
a
14–21°C/r.h., 60–70% for 17h each day; and 3, a three-week period during which they were subjected once more to the thermoneutral
conditions described for 1. Water and a complete feed were constantly available. Compared with water intake (drinking water+feed
water) under thermoneutral conditions cows exposed to treatment 2 significantly increased their mean intake by 12.2%; in three
cows, this involved a phase-shift of >20% in drinking habits from day (hot) to night (cool) time. Water balance trials conducted
at the mid-point of each treatment revealed that the mean losses of water via urine, faeces, milk, sweat and saliva as a percentage
of water intake changed significantly resulting in a net gain (retention) of body water. An accompanying significant increase
in live weight despite a 9.1% decrease in DM intake during treatment 2 confirmed the water retention results. On return to
thermoneutral conditions (3), the cows exhibited a marked weight loss and a significant increase in urinary water excretion
over treatment 1 and 2 values, signifying that a large proportion of the water retained during 2 was of extracellular origin.
A positive correlation was found between the severity of the clinical and behavioural responses of the individual cows during
2 and their retention of water.
Resumen Cuatro vacas Friesian primíparas, en la mitad de la lactancia, fueron expuestas en cabinas climáticas a tres tratamientos diferentes consecutivos: I—a un período de tres semanas en un ambiente termoneutro (temperatura ambiente, Ta 14–21°C y humedad relativa HR 60–70%); II—durante período similar, fueron expuestas a una Ta máxima de 38°C/HR máxima de 80% por siete horas y Ta 14–21°C/HR 60–70% por diecisiete horas cada día; y III—durante un período de tres semanas fueron sometidas otra vez a las condiciones termoneutras descritas en el tratamiento I. Agua y un alimento completo estuvieron siempre a disposición. Comparado con el consumo de agua (agua de bebida+agua de alimento) bajo condiciones termoneutrales, las vacas sometidas al tratamiento II incrementaron significativamente su consumo medio en un 12.2%; en tres vacas esto significó un cambio de >20% en hábitos de bebida, del día caluroso a la noche tibia. Los ensayos de balance de agua conducidas en la mitad de cada tratamiento, revelaron que las pérdidas medias de agua via orina, heces, leche, sudor y saliva, como porcentaje del agua ingerida cambió significativamente, resultando en una ganancia neta (retención) de agua corporal. Se observó tambien un incremento significativo en peso vivo de 16.8±7.3 (SE) kg/animal, a pesar de la disminución de 9.1% en la igestión de MS durante el tratamienta II, confirmando así la retención de agua. Bajo condiciones termoneutrales (III), las vacas exhibieron pérdida marcada de peso y un incremento significativo en la exreción de agua, sobre los valores de los tratamientos I y II, indicando así que una proporción alta del agua retenida durante II fue de origen extracelular. Se encontró tambien una correlación positiva entre la severidad de las respuestas clínicas y de conducta de las vacas individuales durante II, con la retención de agua.
Résumé Quatre vaches frisonnes primipares, à mi-lactation et logées dans des chambres climatisées ont été simultanément exposées à 3 traitements climatiques séquentiels: I. une période de 3 semaines dans un environnement thermique neutre (température ambiante, Ta 14–21°C et humidité relative, HR 60–70 p. 100); II. une période similaire pendant laquelle elles étaient exposées à Ta max. 38°C/HR max. 80 p. 100 pendant sept heures et à Ta 14–21°C/HR 60–70 p. 100 pendant dix sept heures chaque jour; et III une période de 3 semaines pendant laquelle elles étaient de nouveau soumises aux conditions thermiques neutres décrites en I. L'eau et un aliment complet étaient constamment disponibles. Par comparaison avec leur absorption totale d'eau (abreuvement plus eau de constitution des aliments) dans des conditions thermiques neutres, les vaches soumises au traitement II ont augmenté significativement leur absorption moyenne de 12,2 p. 100: chez 3 vaches, ceci a entra?né un décalage dans le temps supérieur à 20 p. 100 de l'absorption diurne (période chaude) à l'absorption nocturne (période fra?che). Des essais d'équilibre hydrique effectués au milieu de chaque traitement ont révélé que les pertes moyennes en eau par les urines, les fèces, le lait, la sueur et la salive, en tant que pourcentage de l'eau absorbée changeait de fa?on significative, ce qui s'est traduit par un gain net (retention) d'eau corporelle. Une augmentation significative concommittante du poids vif de 16,8+7,3 (SE) kg par animal, en dépit d'une diminution de 9,1 p. 100 de l'ingestion de MS pendant le traitement II a confirmé les résultats de rétention d'eau. De retour aux conditions thermiques neutres (III) les vaches ont montré une perte de poids marquée et une augmentation significative de l'excrétion d'eau urinaire, par rapport aux valeurs relevées pendant les traitements I et II, ce que signifie qu'une grande proportion de l'eau retenue au cours du traitement II était d'origine extracellulaire. Une corrélation positive a été observée entre la gravité des réponses cliniques et de comportement des individus en II et leur rétention d'eau.相似文献
7.
Reasons for performing study: Radial strain in normal hooves has been found to vary with strain gauge location, limb posture and sample limb but reported magnitudes were considered to be low. More accurate measurement of radial strain may enhance the understanding of hoof function. Objectives: To explore in vitro radial hoof strain in relation other kinetic and kinematic variables that may be related. Methods: Five normal forelimbs were removed at the proximal articular surface of the third metacarpal bone (McIII). The limbs were loaded using a modified Instron test machine. Six calibrated infrared cameras captured movement from markers on the hoof and bone fixed markers on the second and first phalanxes and McIII, whilst radial hoof strain was measured using a calibrated instrumented plug. Change in strain, joint angle and load were found at simulated walking postures and bivariate correlations were used to compare the relationships between them. Results: Radial strain was moderately correlated with proximal interphalangeal joint (PIPJ) rotation (r =?0.519). Large reductions in radial strain were found in loading and midstance with 10° of heel lift postures. Conclusions and potential relevance: PIPJ rotation has previously been linked to the magnitude of deep digital flexor tendon (DDFT) loads and it is therefore suspected that these loads may have the greatest influence on radial strain magnitudes. Further investigation of radial strain is needed to describe the patterns fully during the stance phase in vivo. 相似文献
8.
A survey was carried out to determine the prevalence and seasonal abundance of the egg and adult stages of nematode parasites of sheep and goats in the semi-arid zone of north-eastern Nigeria between January and December 2002. Faecal samples collected from 102 sheep and 147 goats and examined by the modified McMaster technique using saturated solution of sodium chloride as the floating medium revealed that 44 (43.1%) and 82 (55.8%) of the samples, respectively, contained at least one nematode egg type. Three nematode egg types were recovered with strongyle egg type (22.5% in sheep and 35.4% in goats) being the most prevalent followed, respectively, by Trichuris (5.9% in sheep and 4.1% in goats) and Strongyloides (4.9% in sheep and 4.1% in goats) egg types. Mean faecal egg counts were generally moderate in both sheep (1052+/-922 strongyle, 1000+/-590 Strongyloides and 380+/-110 Trichuris eggs, respectively, per g of faeces) and goats (2092+/-3475 strongyle, 958+/-854 Strongyloides and 683+/-512 Trichuris eggs, respectively, per g of faeces) and showed the same trend irrespective of the age or sex of the animals. The prevalence and counts of strongyle nematode eggs showed a definite seasonal sequence that corresponded with the rainfall pattern in the study area during the period. In both sheep and goats, counts of strongyle egg type increased with the rains and reached peak levels at about the peak of the rainy season in September. The other egg types encountered during the study did not show much variation with the season of the year. Out of the 45 sheep and 75 goats examined at necropsy, 27 (60%) and 39 (52%), respectively, contained adult nematode species. Seven genera of adult nematodes including Strongyloides, Trichostrongylus, Haemonchus, Trichuris, Cooperia, Oesophagostomum and Bunostomum species were encountered during the study. Bunostomum species were recorded only in sheep. Adult worm burdens were generally low and showed seasonal variation that corresponded with the rainfall pattern in the study area during the period. Haemonchus and Trichostrongylus species attained peak counts together in both goats (June) and sheep (August). Strongyloides species were encountered throughout the year in both sheep and goats irrespective of the season. Other genera of nematodes encountered occurred in very low numbers and did not allow any meaningful comparison of seasonal sequence. The results suggest that Haemonchus, Trichostrongylus and Strongyloides species may be the major contributors to small ruminant helminthiasis in the study area. 相似文献
9.
Adiposity and adiponectin in dogs: investigation of causes of discrepant results between two studies
Verkest KR Rose FJ Fleeman LM Rand JS Morton JM Richards AA Ishioka K Whitehead JP 《Domestic animal endocrinology》2011,41(1):35-41
Although one study showed lower adiponectin concentrations in obese dogs, other recent studies indicate that adiponectin might not be decreased in obese dogs, raising the possibility that the physiology of adiponectin is different in dogs than in humans. The aim of this study was to investigate possible causes of the discrepancy between the two largest studies to date that assessed the association between adiposity and adiponectin concentration in dogs, including the validity of the assay, laboratory error, and the effects of breed, sex, and neuter status on the relationship between adiposity and adiponectin concentrations. Adiponectin concentrations measured with a previously validated adiponectin ELISA were compared with those estimated by Western blotting analysis of reduced and denatured plasma samples. The possibility of laboratory error and the effect of EDTA anticoagulant and aprotinin were tested. Adiponectin concentration was measured by ELISA in 20 lean dogs (10 male and 10 female, 5 neutered in each sex). There was close correlation between adiponectin concentrations measured by ELISA and those estimated by Western blotting analysis (r = 0.90; P < 0.001). There was no substantial effect of EDTA, aprotinin, or laboratory error on the results. There was confounding by neuter status of the relationship between adiposity and adiponectin concentrations, but adiponectin concentrations were not significantly lower in male than in female lean dogs (females, 36 mg/L; males, 26 mg/L; P > 0.20) and were not significantly lower in intact than in neutered lean male dogs (intact, 28 mg/L; neutered, 23 mg/L; P = 0.49). We conclude that the adiponectin ELISA previously validated for use in dogs appears to be suitable for determination of canine adiponectin concentrations and that testosterone does not appear to have a strong effect on plasma adiponectin concentrations in dogs. Obesity might decrease adiponectin concentrations in intact but not in neutered dogs. 相似文献
10.