全文获取类型
收费全文 | 16524篇 |
免费 | 1篇 |
国内免费 | 1篇 |
专业分类
林业 | 3628篇 |
农学 | 1295篇 |
基础科学 | 140篇 |
2772篇 | |
综合类 | 717篇 |
农作物 | 2100篇 |
水产渔业 | 1787篇 |
畜牧兽医 | 1084篇 |
园艺 | 1123篇 |
植物保护 | 1880篇 |
出版年
2023年 | 1篇 |
2022年 | 2篇 |
2021年 | 2篇 |
2020年 | 3篇 |
2019年 | 5篇 |
2018年 | 2746篇 |
2017年 | 2705篇 |
2016年 | 1185篇 |
2015年 | 68篇 |
2014年 | 18篇 |
2013年 | 23篇 |
2012年 | 800篇 |
2011年 | 2133篇 |
2010年 | 2106篇 |
2009年 | 1263篇 |
2008年 | 1321篇 |
2007年 | 1578篇 |
2006年 | 34篇 |
2005年 | 114篇 |
2004年 | 103篇 |
2003年 | 156篇 |
2002年 | 61篇 |
2001年 | 6篇 |
2000年 | 41篇 |
1999年 | 1篇 |
1995年 | 1篇 |
1993年 | 12篇 |
1992年 | 7篇 |
1990年 | 1篇 |
1989年 | 5篇 |
1988年 | 12篇 |
1987年 | 1篇 |
1985年 | 1篇 |
1977年 | 4篇 |
1972年 | 1篇 |
1969年 | 1篇 |
1968年 | 4篇 |
1967年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
K Ashley S Wilson JR Young HP Chan S Vitou S Suon PA Windsor RD Bush 《Tropical animal health and production》2018,50(1):63-73
Forage technology has been successfully introduced into smallholder cattle systems in Cambodia as an alternative feed source to the traditional rice straw and native pastures, improving animal nutrition and reducing labour requirements of feeding cattle. Previous research has highlighted the positive impacts of forage technology including improved growth rates of cattle and household time savings. However, further research is required to understand the drivers, challenges and opportunities of forage technology for smallholder cattle households in Cambodia to facilitate widespread adoption and identify areas for further improvement. A survey of forage-growing households (n = 40) in July–September 2016 examined forage technology adoption experiences, including reasons for forage establishment, use of inputs and labour requirements of forage plot maintenance and use of forages (feeding, fattening, sale of grass or seedlings and silage). Time savings was reported as the main driver of forage adoption with household members spending approximately 1 h per day maintaining forages and feeding it to cattle. Water availability was reported as the main challenge to this activity. A small number of households also reported lack of labour, lack of fencing, competition from natural grasses, cost of irrigation and lack of experience as challenges to forage growing. Cattle fattening and sale of cut forage grass and seedlings was not found to be a widespread activity by interviewed households, with 25 and 10% of households reporting use of forages for these activities, respectively. Currently, opportunities exist for these households to better utilise forages through expansion of forage plots and cattle activities, although assistance is required to support these households in addressing current constraints, particularly availability of water, if the sustainability of this feed technology for smallholder cattle household is to be established in Cambodia. 相似文献
52.
53.
Mersha Chanie Tamiru Negash Asegedech Sirak 《Tropical animal health and production》2010,42(6):1103-1109
Ectoparasites are the major causes of skin lesions in animals. Clinical, skin scraping examination, and histopathological
studies were conducted to identify and characterize skin lesions in small ruminants caused by ectoparasites. Mange mites,
lice, sheep keds, and ticks were collected from the skin of affected animals for species identification. Skin biopsies were
collected from affected part of the skin and fixed in 10% neutral buffered formalin for histopathology. Of 1,000 sheep and
600 goats examined, 815 (81.50%) sheep and 327 (54.5%) goats were infested with one or more types of ectoparasites. Sarcoptes scabiei var ovis, Demodex ovis, Psoroptes ovis, Bovicola ovis, Melophagus ovinus, and Amblyomma variegatum and other tick species were identified from sheep. S. scabiei var caprae, Demodex caprae, Linognathus stenopsis, and A. variegatum and other tick species were identified from goats. Gross skin lesions or defects observed on the skin include stained and
ragged wool, loss of wool/hair, nodules, crusts, lichenification, and fissuring. Microscopic evaluation of H and E stained
skin sections revealed lesions in the epidermal layer such as hyperkeratosis, acanthosis, and melanin inconsistency on the
basal cells of the epidermis. Follicular keratosis, perifolliculitis, frunculosis, perivasculitis, and aggregates of inflammatory
cells (of acute and chronic type) with fibrosis were experiential in the dermal layer of the skin. Most of the skin lesions
caused by ectoparasites are overlapping. Thus, ectoparasites control program should be executed to reduce skin lesions as
skins are the major export commodity of the country. 相似文献
54.
Ahmad Oryan Fatemeh Namazi Mohammad-Mehdi Namavari Hassan Sharifiyazdi Marjan Moraveji 《Veterinary research communications》2010,34(5):423-434
This study was performed to evaluate the infectivity of bradyzoites of two Besnoitia caprae isolates, BC-1 and BC-2, to inbred BALB/c mice. Each group of inbred BALB/c mice was inoculated intraperitoneally with 1 × 103, 1 × 104, 1 × 105, 5 × 105 and 1 × 106 of one of the two isolates of B. caprae bradyzoites. The mice were monitored daily for a period of 40 days for survival. After death of each mice, several passages
from its peritoneal washing and tissues were analyzed using ribosomal DNA-specific PCR assay. Marked differences in pathogenicity
between the isolates were seen. All the inbred BALB/c mice infected with BC-2 survived but all the mice that were administered
with 1 × 05, 5 × 105 and 1 × 106 BC-1 bradyzoites were died within 4–9 days post-infection (DPI). Histopathological examination of the tissues of the dead
mice revealed hyperemia and necrosis with presence of mononuclear and polymorphonuclear cell infiltration in myocardium, spleen
and intestines together with interstitial pneumonia and peritonitis. All inbred BALB/c mice in the 1 × 103 and 1 × 104 groups of BC-1 inoculated mice survived and they were euthanized after 40 DPI. Chronic inflammation with infiltration of
mononuclear cells was evident in myocardium, spleen, alveolar septa of the lungs of most of the examined tissues with hemorrhagic
enteritis in the mice infected with 1x106 bradyzoites. The mice infected with different doses of BC-2 were euthanized after 40 DPI and no lesion was seen in histopathological
sections of their organs. All peritoneal washings and examined tissues were PCR positive in BC-1 group. This experiment is
the first report to show inbred BALB/c mice as a relevant model for B. caprae and demonstrates that this strain of inbred BALB/c mice is a suitable animal model for biological studies and examination
of pathogenesis for this species of Besnoitia. The present findings also provide evidence for significant differences between the two isolates of B. caprae. 相似文献
55.
The effect of a single intramammary infusion of a biological response modifier in cows at drying off
Bibiana Elisabet Dallard H. H. Ortega I. A. Iguzquiza N. R. Salvetti O. A. Quaino L. F. Calvinho 《Veterinary research communications》2010,34(6):519-532
Biological response modifiers (BRM) are compounds that interact with the immune system to regulate specific aspects of host
response. The objective of this study was to describe clinical and morphological changes during involution of bovine mammary
gland following a single-dose infusion of a BRM containing lipopolysaccharide and cellular fractions of Escherichia coli incorporated into liposomes. A massive leukocyte response and increased subepithelial stroma infiltration of mononuclear
cells, eosinophils and mast cells was observed in BRM-treated quarters compared with untreated controls; however, morphologic
parameters assessed at 11 days post infusion were indicative of only slightly accelerated involution compared with untreated
controls. In addition, BRM infusion at the end of lactation did not interfere with mammary epithelial cell proliferation and
caused only mild systemic effects. 相似文献
56.
Getachew AM Innocent G Trawford AF Reid SW Love S 《Tropical animal health and production》2012,44(4):757-762
A retrospective study was conducted to investigate the cause of rectal prolapse in working donkeys in Ethiopia. Analysis of
data on rectal prolapse cases obtained from the Donkey Health and Welfare Project clinic at the School of Veterinary Medicine,
Addis Ababa University, from 1995 to 2004 revealed that 83.6% (n = 177) of the cases were associated with Gasterophilus nasalis. The rest 10.7% and 5.7% were associated with work-related (overloading) cause and diarrhoea, respectively. The mean and
median numbers of G. nasalis recovered from the rectum of infected donkeys were 66 and 64, respectively, with a range of 2–195. Over 100 G. nasalis larvae were recovered from the rectum of 22% of the donkeys. Circular demarcated ulcer-like and deep circumferential pits
or ring-like mucosal lesions were found at the larval attachment sites. G. nasalis infection and the associated rectal prolapse were observed year round. However, the intensity of rectal larval infection
and incidence of rectal prolapse were significantly higher during the rainy season (P < 0.01). Age and sex of the donkeys had no significant effect on the intensity of rectal larval infection and incidence of
rectal prolapse (P > 0.05). 相似文献
57.
Eighteen multiparous Zebu cows in their third lactation and their calves were randomly allocated to three suckling periods, up to 3, 4 or 5 months of age of the calf. The cows were individually fed natural hay, cottonseed cake and molasses. At 2 months of age, all calves were separated from their mothers, and were offered cottonseed cake mixed with molasses and Mucuna hay individually. The calves stimulated milk ejection by suckling 30 seconds and suckled the residual milk for 45 minutes after milking. The dry matter intake of cows (3.68, 3.29 and 3.31% of body weight) and calves (2.88, 2.80 and 2.55% of body weight) for suckling up 3, 4 and 5 months of age, respectively, was not significantly affected by treatment and neither was the growth rate of the calves (178, 157 and 149 g/d for 3, 4 or 5 months suckling period, respectively). Cows suckling their calves up to 5 months had significantly higher milk yield and higher amount of saleable milk (1.97, 2.93 and 3.69 kg/cow/d for 3, 4 and 5 months suckling period, respectively). The fat content of the milk decreased with increasing length of the suckling period while the protein content was not affected. In conclusion, a suckling period of 5 months resulted in higher total milk production and higher amount of saleable milk but did not seem to have any effect on calf growth when the calves were supplemented. 相似文献
58.
Monde Mapekula Michael Chimonyo Cletos Mapiye Kennedy Dzama 《Tropical animal health and production》2010,42(7):1413-1419
Understanding the utilisation patterns of milk assists in designing appropriate dairy development schemes in rural communities.
The objective of the study was to determine milk utilisation patterns in different smallholder farming systems in the Eastern
Cape Province of South Africa. Data were collected through the administration of recording sheets to 130 randomly selected
households in Alice, Fort Beaufort and Queenstown districts. Amounts of milk produced per household ranged from 9 to 21 l
per household per day. Milk consumption/household/day was similar among the three districts. Milk consumption in the early
lactation doubled the amount consumed in late lactation (P < 0.05). Milk in the communal areas was largely utilised as fresh or sour milk. Fresh milk was mostly used in tea/coffee
or to make porridge for children. Sour milk was consumed with thick boiled maize meal. Fort Beaufort (10.2 ± 1.37 l/day) had
the highest sour milk sales whilst Queenstown had the highest fresh milk sales (9.7 ± 5.57 l/day). It was concluded that quantities
of milk consumed or sold as fresh or sour were generally low and varied across smallholder farming systems. 相似文献
59.
Kagira JM Kanyari PN Githigia SM Maingi N Ng'ang'a JC Gachohi JM 《Tropical animal health and production》2012,44(3):657-664
Nematode infections are a serious constraint to pig production, especially where free range pig keeping is practiced. This
study investigated the epidemiology of nematodes in free range pigs in Busia District, Kenya. Three hundred and six pigs from
135 farms were sampled for faeces that were analysed for nematode eggs per gram (EPG) of faeces using the McMaster technique.
The nematode eggs were also identified to genus and species based on morphology. A questionnaire on risk factors was also
administered to the pig owners. The overall prevalence and mean nematode EPG were 84.2% and 2,355, respectively. The nematode
eggs were identified as those belonging to Oesophagostomum spp. (75%), Strongyloides ransomi (37%), Ascaris suum (18%), Metastrongylus spp. (11%), Trichuris suis (7%) and Physocephalus sexalatus (3%). The prevalence of nematodes was positively correlated (p < 0.05) with the amount of rainfall in the division of the pigs' origin (all nematodes except S. ransomi). The prevalence of nematodes was also associated with the age of the pigs. A lower burden of nematodes was associated (p < 0.05) with a history of deworming (A. suum) and the provision of night housing (S. ransomi and Metastrongylus spp.). In conclusion, this study has provided information on nematode infections and the associated risk factors for free
range pigs in Busia District, which can be used when implementing integrated control measures. 相似文献
60.
Hussain R Auon M Khan A Khan MZ Mahmood F Ur-Rehman S 《Tropical animal health and production》2012,44(3):477-481
Seroprevalence, clinical findings, and lesions of contagious caprine pleuropneumonia (CCPP) in Beetal goats were recorded
during an outbreak. The overall seroprevalence of CCPP was 32.50%. Confirmation of Mycoplasma mycoides in serum was carried out using counter immunoelectrophoresis (CIE) technique. The highest CIE-positive cases were recorded
in the older goats (51.72%) as compared to young ones. Nasal swabs collected from 39 goats showing respiratory signs were
found positive for M. mycoides. The most consistent clinical findings were mild to severe cough, purulent nasal secretion, emaciation, dyspnea, increased
respiration rate, and pyrexia. Mortality due to CCPP was 9.17%. Consolidation of lungs exhibited the highest frequency (100%),
followed by alveolar exudation (90.90%) and pleural adhesion (72.72%). Among the microscopic lesions, septal peribronchiolar
fibrosis exhibited the highest frequency (81.81%), followed by fibrinous pleuritis (63.63%) and peribronchiolar cuffing of
mononuclear cells (54.54%) in lungs. From these results, it was concluded that CCPP under subtropical conditions has high
prevalence in Beetal goats and leads to significant mortality. 相似文献