全文获取类型
收费全文 | 231篇 |
免费 | 1篇 |
专业分类
林业 | 11篇 |
农学 | 5篇 |
23篇 | |
综合类 | 43篇 |
农作物 | 1篇 |
水产渔业 | 19篇 |
畜牧兽医 | 121篇 |
植物保护 | 9篇 |
出版年
2020年 | 2篇 |
2018年 | 3篇 |
2016年 | 3篇 |
2014年 | 2篇 |
2013年 | 7篇 |
2012年 | 3篇 |
2011年 | 2篇 |
2010年 | 9篇 |
2009年 | 2篇 |
2007年 | 2篇 |
1998年 | 7篇 |
1997年 | 8篇 |
1996年 | 5篇 |
1995年 | 7篇 |
1994年 | 2篇 |
1993年 | 8篇 |
1992年 | 2篇 |
1991年 | 9篇 |
1990年 | 14篇 |
1989年 | 7篇 |
1988年 | 5篇 |
1987年 | 6篇 |
1986年 | 5篇 |
1985年 | 3篇 |
1984年 | 3篇 |
1983年 | 2篇 |
1982年 | 7篇 |
1980年 | 3篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1977年 | 3篇 |
1976年 | 4篇 |
1975年 | 2篇 |
1974年 | 3篇 |
1972年 | 2篇 |
1968年 | 2篇 |
1963年 | 3篇 |
1962年 | 2篇 |
1961年 | 3篇 |
1959年 | 1篇 |
1958年 | 11篇 |
1957年 | 7篇 |
1956年 | 7篇 |
1955年 | 5篇 |
1954年 | 6篇 |
1953年 | 8篇 |
1951年 | 1篇 |
1950年 | 1篇 |
1948年 | 4篇 |
1946年 | 3篇 |
排序方式: 共有232条查询结果,搜索用时 359 毫秒
81.
The Republic of Maldives in the central Indian Ocean is home to large numbers of manta rays, Manta alfredi. They are known to undertake seasonal migrations within the Maldives, but these movements have not been well documented. The aims of this study were to map the seasonal distribution of manta rays within the Maldives, and to provide some indications of the physical and biological oceanographic processes affecting their distribution. The seasonal distribution of mantas was determined from a national survey of fishermen, interviews with experienced divers and personal observations. The data demonstrate that the distribution of mantas is strongly influenced by the seasonally reversing monsoon currents. Mantas occur on the downstream sides of the atolls, and are rare on the upstream sides, switching sides biannually as the monsoon currents change direction. These seasonally alternating currents are driven by monsoon winds which also alternate according to the season, and bring clear oceanic water to the upstream sides of the atolls. As the currents pass over the Maldives ridge, nutrient‐rich waters are lifted to the surface, promoting phytoplankton blooms (as demonstrated by the distribution of chlorophyll‐a) on the downstream sides of the atolls. This manifestation of the island mass effect supports an abundance of zooplankton, which in turn supports the manta rays. 相似文献
82.
83.
SUMMARY The analysis of records for 75 821 herd tests on 23 700 cows in the Macalister Irrigation District of East Gippsland, using a model that also included stage of lactation, herd and cow effects, found a strong relationship between somatic cell count and milk production. Unit increases in the natural logarithm of the somatic cell count were associated with decreases in production of up to 2.6% in the range 54 598 to 403 429 cells per mL. This is equivalent to a decrease of 1.9% for a doubling of cell count from 100 000 to 200 000 cells per mL. Subclinical mastitis was assessed to be a significant source of loss in milk production in the study area. 相似文献
84.
WILLIAM H. MILLER Jr. WAYNE I. ANDERSON JOSEPH P. McCANN 《Veterinary dermatology》1991,2(3-4):179-182
Abstract— A 5-year-old mongrel dog developed necrolytic migratory erythema secondary to a glucagon-secreting α cell tumor. The dog was anemic, glucose intolerant, and hyperglucagonemic but liver function tests were within normal limits. Metastatic tumor cells were found in the liver but the primary tumor was not identified.
Résumé— Un chien croisé mâle de 5 ans a développé un Erythème nécrolytique migrant secondaire à un glucayonome. L'animal était anémié, présentait une intolérance au glucose et une hyperglucagonémie, avec des tests fontcionnels hépatiques dans les limites des valeurs usuelles. Des cellules métastaiques tumorales ont été retrouvées dans le foie, mais la tumeur primitive n'a pas été identifiée.
Zusamenfassung —Ein 5 Jahr alter Mischingshund entwickelte sekundär auf einen Glukagon-sezernierenden Tumor ein nekroyltisches Erythema migrans. Das Tier war anämisch, Glukose-intolerant und hyperglukagonämische; die Leberfunktionstests befanden sich jedoch innerhalb normaler Grenzwerte. Matastatische Tumorzellen waren in der Leber nachweisbar, der Primärtumor konnte jedoch nicht identifizert werden.
Resumen Un perro cruzado de 5 años desarrollo un eritema necrolítico migratorio, secundario a un tumor de celulas secretoras de glucógeno. El perro era anémico, presentaba intolerancia a la glucosa, e hiperglucogenia, pero los resultados de los tests que evaluaban la función hepática feuron normales. Se encontraron células tumorales metastásicas procedentes del hígado, pero el tumor primario no se identificó. Se encontraron células tumorales metastásicas procedentes del hígado, pero el tumor primario no se identificicó. 相似文献
Résumé— Un chien croisé mâle de 5 ans a développé un Erythème nécrolytique migrant secondaire à un glucayonome. L'animal était anémié, présentait une intolérance au glucose et une hyperglucagonémie, avec des tests fontcionnels hépatiques dans les limites des valeurs usuelles. Des cellules métastaiques tumorales ont été retrouvées dans le foie, mais la tumeur primitive n'a pas été identifiée.
Zusamenfassung —Ein 5 Jahr alter Mischingshund entwickelte sekundär auf einen Glukagon-sezernierenden Tumor ein nekroyltisches Erythema migrans. Das Tier war anämisch, Glukose-intolerant und hyperglukagonämische; die Leberfunktionstests befanden sich jedoch innerhalb normaler Grenzwerte. Matastatische Tumorzellen waren in der Leber nachweisbar, der Primärtumor konnte jedoch nicht identifizert werden.
Resumen Un perro cruzado de 5 años desarrollo un eritema necrolítico migratorio, secundario a un tumor de celulas secretoras de glucógeno. El perro era anémico, presentaba intolerancia a la glucosa, e hiperglucogenia, pero los resultados de los tests que evaluaban la función hepática feuron normales. Se encontraron células tumorales metastásicas procedentes del hígado, pero el tumor primario no se identificó. Se encontraron células tumorales metastásicas procedentes del hígado, pero el tumor primario no se identificicó. 相似文献
85.
The speed and accuracy of 4 ultrasonic devices (Scanopreg, Pregmatic 3, Medata external probe and Medata rectal probe) were compared with udder scoring and harnessed vasectomised rams as methods of pregnancy diagnosis in 177 ewes, 59 of which were non-pregnant. When using the Scanopreg in ewes of greater than 50 days gestation, accuracy in pregnant ewes averaged 98% and in non-pregnant ewes 87%. The Pregmatic 3 was 97% accurate in pregnant ewes after 50 days gestation and was 96% accurate in non-pregnant ewes. Ewes were examined at between 85 and 185 per hour using these devices. The Medata external probe was 99% accurate in pregnant ewes of greater than 110 days gestation but less accurate in early gestation. This instrument averaged 89% accuracy in non-pregnant ewes and an examination rate of 29 to 35 ewes per hour was achieved. The Medata rectal probe averaged 85% accuracy in pregnant ewes after 70 days gestation. Accuracy averaged 94% in non-pregnant ewes. Ewes were examined at between 35 and 59 per hour using this device. After 130 days gestation 84% of ewes had firm, obviously enlarge udders and another 14% had slight to moderate udder development. After 130 days gestation thick, clear udder secretions were expressed from 18% of ewes and thick, milky udder secretions were expressed from 8%. Harnessed vasectomised rams raddled one of 118 pregnant ewes (an accuracy in pregnant sheep of 99%) and raddled 53% of non pregnant ewes. It was concluded that the ultrasonic pregnancy testing devices have a commercial role, especially as aids to decision making.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
86.
D. B. GALLOWAY P. BRIGHTLING J. MALMO G. A. ANDERSON M. T. LARCOMBE P. J. WRIGHT 《Australian veterinary journal》1987,64(6):187-189
In seasonally calving dairy herds in the Macalister Irrigation Area of Gippsland, Victoria, cows that had not been observed in oestrus by the start of the mating season and which had inactive ovaries based on rectal palpation and progesterone assay were treated with a hormonal treatment (n = 49). Mature cows had calved at least 40 days previously and 2-year-olds had been calved at least 60 days. The treatment consisted of a norgestomet implant and a norgestomet and oestradiol injection on day 1; prostaglandin analogue Prosolvin) on day 8; withdrawal of implant on day 10 and an injection of PMSG; and fixed time artificial insemination 54 to 56 h after implant withdrawal. This treatment was called the Syncro-mate regimen. Control cows (n = 46) were injected with water on days 1, 8 and 10 and artificially inseminated or served by a bull when seen on heat. Forty seven percent of the treated cows became pregnant within 14 days from the start of treatment compared with 20% of control cows (P less than 0.01). There was an effect of age group on the response to treatment. A greater proportion of 2-year-old cows than mature cows became pregnant within 14 days of treatment (79% of 19 v. 27% of 20; Chi square interaction, treatment by age, 6.4, P less than 0.05). In the younger cows there was also a gain of 22 days in the treatment to conception interval over the control cows (P less than 0.001). It was concluded that the Syncro-mate regimen can be an effective treatment for post partum anoestrus in dairy cows under certain conditions. 相似文献
87.
Six cats with chronic recurrent rhinitis and frontal sinusitis were treated by surgical ablation of their frontal sinuses by the implantation of autogenous fat grafts and curettage of the remaining ethmoid conchae. Deep nasal bacterial cultures and skull radiographs were performed before surgery. Excellent results were achieved in four of six cats and there was significant improvement in two of six cats. Median follow-up time was 15 months. Subcutaneous emphysema over the temporal area was managed by needle aspiration and bandaging. Frontal sinus ablation with autogenous fat graft in combination with ethmoid conchal curettage appears to be an effective treatment for chronic sinusitis in cats. 相似文献
88.
A Comparison of Nonthreaded, Enhanced Threaded, and Ellis Fixation Pins Used in Type I External Skeletal Fixators in Dogs 总被引:1,自引:0,他引:1
M. A. ANDERSON dvm ms F. A. MANN dvm ms Diplomate acvs C. WAGNER-MANN dvm PhD A. W. HAHN DVM PhD Diplomate ACVIM B. L. JIANG PhD J. L. TOMLINSON DVM MVSci Diplomate ACVS 《Veterinary surgery : VS》1993,22(6):482-489
Three different pin types (Ellis, enhanced threaded, and nonthreaded) were used in type 1 external skeletal fixation after transverse osteotomy of the radius and ulna in 12 skeletally mature dogs. Dogs were placed into three groups of four dogs based on the pin type used. Axial extraction forces were determined for each of the pin types after 8 weeks of weight bearing (chronic study). Nine contralateral radii were used to determine axial extraction forces for nine of each pin type not subjected to weight bearing forces (acute study). The force required for extraction of the enhanced threaded and Ellis pins in the chronic and acute studies was not significantly different. The force required to extract the nonthreaded pins was significantly less than that required for the other two pin types. Ground reaction forces had returned to levels measured before surgery by 2 weeks after surgery in the enhanced threaded and Ellis pin groups, however, dogs in the nonthreaded pin group required 4 weeks until normal ground reaction forces were measured. Radiographic evaluations 1,2,4, 6, and 8 weeks after surgery showed no difference among groups in the number of pin tract radio-lucencies, however, the enhanced threaded pins had caused more trans-cortical chip fractures than the other two pin types. None of the pins broke during the eight-week chronic study. 相似文献
89.
Pigs obtained from a mycoplasma-free piggery were randomised into 4 groups of 9. Groups 1 and 2 were injected by the intraperitoneal route with liquid culture of the LKR strain of Mycoplasma hyopneumoniae. Group 1 was injected once and group 2 twice. Group 3 was made up of pigs inoculated by the intranasal route with the virulent Beaufort strain of M. hyopneumoniae; they served as the source of infection for the challenge. Group 4 were uninfected, uninjected controls. Six weeks after the last injection, groups from 1 to 4 were placed in contact. Seven of the pigs in the 1-dose group and 6 in the 2-dose group were free of lesions at necropsy 6 weeks after challenge. Of the two pigs with lesions in the 1-dose group one had only a small lesion but the other had extensive lesions; it had not shown an antibody response after injection of culture. The lesions in the 3 pigs in the 2-dose group were all small. All 9 control pigs had lesions which varied from medium to large in size. The difference in the incidence of pneumonia between the injected and control groups was significant (P less than 0.05) and the proportion of severely affected pigs in the vaccinated groups was significantly lower (P greater than 0.01). There was no difference between those given one dose of vaccine and those receiving 2 doses. 相似文献
90.