全文获取类型
收费全文 | 16630篇 |
免费 | 4篇 |
专业分类
林业 | 3630篇 |
农学 | 1299篇 |
基础科学 | 139篇 |
2755篇 | |
综合类 | 740篇 |
农作物 | 2129篇 |
水产渔业 | 1794篇 |
畜牧兽医 | 1164篇 |
园艺 | 1112篇 |
植物保护 | 1872篇 |
出版年
2021年 | 4篇 |
2020年 | 4篇 |
2019年 | 7篇 |
2018年 | 2746篇 |
2017年 | 2706篇 |
2016年 | 1182篇 |
2015年 | 64篇 |
2014年 | 21篇 |
2013年 | 12篇 |
2012年 | 800篇 |
2011年 | 2141篇 |
2010年 | 2111篇 |
2009年 | 1256篇 |
2008年 | 1331篇 |
2007年 | 1583篇 |
2006年 | 40篇 |
2005年 | 115篇 |
2004年 | 113篇 |
2003年 | 165篇 |
2002年 | 81篇 |
2001年 | 6篇 |
2000年 | 40篇 |
1995年 | 2篇 |
1993年 | 14篇 |
1992年 | 7篇 |
1991年 | 4篇 |
1990年 | 2篇 |
1989年 | 5篇 |
1988年 | 13篇 |
1987年 | 1篇 |
1985年 | 1篇 |
1983年 | 4篇 |
1982年 | 1篇 |
1979年 | 2篇 |
1978年 | 1篇 |
1977年 | 5篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1973年 | 2篇 |
1972年 | 2篇 |
1970年 | 2篇 |
1969年 | 2篇 |
1968年 | 5篇 |
1967年 | 1篇 |
1964年 | 3篇 |
1961年 | 2篇 |
1945年 | 2篇 |
1944年 | 6篇 |
1943年 | 10篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
Circulating oxidative stress status in dromedary camels infested with sarcoptic mange 总被引:2,自引:0,他引:2
Oxidative stress is an imbalance between radical-generating and radical-scavenging activity, resulting in oxidation products
and tissue damage. This study was aimed to evaluate the status of oxidative stress indices in blood of camels naturally infested
with S. scabiei. Forty-seven male camels (Camelus dromedaries) were divided according to the extent of the infested area with Sarcoptes scabiei into four groups, mild (MID, n = 12), moderate (MOD, n = 10), severely infested (SEV, n = 10) and healthy control group (n = 15). Blood was used for determination of red cell count (RBC), hemoglobin (Hb), packed cell volume (PCV), serum nitric
oxide (NO•, a free radical), ascorbate and albumin concentrations, and erythrocytic values of malondialdehyde (MDA, a marker of lipid
peroxidation), protein carbonyls (PC, an indicator of protein oxidation), glutathione (GSH) superoxide dismutase (SOD) and
catalase (CAT). Decreased levels (P < 0.05) of RBC, Hb, PCV, albumin and ascorbate were noticed in MOD and SEV compared to controls with the lowest values (P < 0.05) in SEV except for ascorbate, where MOD did not differ from SEV. Compared to controls, NO• gradually increased (P < 0.05) in MID followed by MOD and SEV, whereas MDA and PC were higher (P < 0.05) in MOD and SEV. PC was higher (P < 0.05) in MOD than SEV. In addition, the antioxidants GSH, SOD and CAT were higher (P < 0.05) in MID and lower (P < 0.05) in MOD and SEV compared to controls. GSH was lower (P < 0.05) in SEV compared to MOD. Besides, Hb was negatively correlated with NO• (r = −0.68, P < 0.001), MDA (r = −0.53, P < 0.001) and PC (r = −0.73, P < 0.001). In conclusion, dromedary sarcoptosis is accompanied by a state of oxidative stress process, which increased by
increasing the area of infestation, and may contribute to the pathogenesis of the disease. 相似文献
32.
Tatsuya Nakayama Michio Jinnai Ryuji Kawahara Khong Thi Diep Nguyen Nam Thang Tran Thi Hoa Le Kieu Hanh Pham Ngoc Khai Yoshinori Sumimura Yoshimasa Yamamoto 《Tropical animal health and production》2017,49(1):31-37
Reports of livestock infections with extended-spectrum beta-lactamase-producing Escherichia coli (ESBL-E) are increasing. Based on interviews conducted over a 6-month period, we found that veterinarians in the Vietnamese province of Thai Binh prefer to prescribe colistin-based drugs (CBD) in chicken farms. We aimed to clarify whether CBD use selects for strains of colistin-resistant ESBL-E. With the cooperation of seven local households, we detected ESBL-E in chickens’ feces after treating chickens with CBD. Phylogenetic groupings and the presence of CTX-M/AmpC genes were determined, and the multi-antibiotic susceptibility of isolates was analyzed. Our results showed that ESBL-E presented in seven chickens’ feces from two households. Seventy-two percent of ESBL-E isolates harbored CTX-M9 and the phylogenetic group A; the colistin minimum inhibitory concentration (MIC) of all isolated ESBL-E ranged from 0.064 to 1 μg mL?1. Moreover, ESBL-E isolates were used to experimentally select for colistin resistance, and the effect of commercial CBD on ESBL-E was investigated. The results showed that an ESBL-E strain with a colistin MIC of 4 μg mL?1 was able to grow in media with CBD. Although CBD treatment was effective, in vitro experiments demonstrated that ESBL-E can easily acquire colistin resistance. Therefore, restrictions on colistin use are necessary to prevent the emergence of colistin-resistant bacteria. 相似文献
33.
Ouédraogo-Koné S Kaboré-Zoungrana CY Ledin I 《Tropical animal health and production》2008,40(2):155-164
Foliage of Afzelia africana, Pterocarpus erinaceus and Khaya senegalensis, from 10 trees per species, was collected every two weeks during the late dry, rainy and cool season to determine the seasonal
effects on chemical composition. Fifteen rams of the Djallonké breed, weighing on average 20.0 kg, were used to evaluate the
voluntary intake and digestibility of hay of A. gayanus, foliage of A. africana (as a sole feed), and A. africana, P. erinaceus and K. senegalensis offered with 30% of the diet as A. gayanus hay. The crude protein (CP) content of A. africana, and P. erinaceus decreased significantly from the late dry season to the cool season when that of K. senegalensis tended to increase. The mean CP of A. africana, P. erinaceus and K. senegalensis differed significantly (173 g, 139 g and 114 g/kg DM, respectively). The DM intake of A. africana offered with hay (571 g/d) or as a sole feed (598 g/d) were not significantly different, but was higher than that of P. erinaceus (428 g/d) and K. senegalensis (298 g/d). The digestibility calculated by difference of DM and CP of A. africana (582 g/kg DM and 795 g/kg CP, respectively) did not differ significantly from A. africana as a sole feed, but were higher than for the other species. The nutritive value of A. africana seems to justify the high preference of herders for this species. 相似文献
34.
S. Kennou Sebei R. Bergaoui M. Ben Hamouda R. G. Cooper 《Tropical animal health and production》2009,41(7):1427-1438
The aim of the current investigation was to determine wild ostrich reproductive behaviour in Orbata Nature Reserve by observing
16 hens and 28 cocks over a seven-year period. Intense laying commenced in January, one month after the cessation of the rainy
season, and 92% of the eggs were produced during the dry season (January to May, peaking in March). Over the seven years,
1,322 eggs were laid in 69 nests, which corresponded to an annual average production of 19.2 ± 9.1 eggs/nest and 11.8 eggs/hen.
24 nests (34.78%) were non-brooded, 17 nests (24.64%) were deserted in the course of incubation, and 28 nests (40.58%) possessed
hatched eggs. All the non-incubated nests had egg losses equivalent to 46.6 ± 12.6%. Hatchability success of incubated eggs
was 41.9 ± 12.0%. Ostriches tended to dig their nests adjacent to the reserve enclosure which had direct access by road and
track, the latter subjecting them to human disturbance and predation. The systematic obstruction of these nests stimulated
ostriches to build additional nests within the reserve perimeter. The authors discussed the results recorded in an ostrich
flock in relation to the environmental factors (climatic factors, food disponibility and predation) and suggested possibilities
for improved wildlife management. 相似文献
35.
Effects of tea saponins on rumen microbiota,rumen fermentation,methane production and growth performance—a review 总被引:1,自引:0,他引:1
Reducing methane emission from ruminant animals has implications not only for global environmental protection but also for
efficient animal production. Tea saponins (TS) extracted from seeds, leaves or roots of tea plant are pentacyclic triterpenes.
They have a lasting antiprotozoal effect, but little effect on the methanogen population in sheep. There was no significant
correlation between the protozoa counts and methanogens. The TS decreased methanogen activity. It seems that TS influenced
the activity of the methanogens indirectly via the depressed ciliate protozoal population. The TS addition decreased fungal
population in the medium containing rumen liquor in in vitro fermentation, but no such effect was observed in the rumen liquor
of sheep fed TS. Tea saponins had a minor effect on the pattern of rumen fermentation and hence on nutrient digestion. When
added at 3 g/day in diets, TS could improve daily weight gain and feed efficiency in goats. No positive associative effect
existed between TS and disodium fumarate or soybean oil on methane suppression. Inclusion of TS in diets may be an effective
way for improving feed efficiency in ruminants. 相似文献
36.
Millogo V Norell L Ouédraogo GA Svennersten-Sjaunja K Agenäs S 《Tropical animal health and production》2012,44(5):1017-1025
The aim of the study was to test three different hand-milking techniques (“pull down”, “thumb in”, and “full hand grip”) and
their effects on milk production and teat treatment. This is important since milk production in many tropical areas still
rely on hand-milking. The study was carried out at a peri-urban farm in the Bobo-Dioulasso area in Burkina Faso. Twelve indigenous
Zebu cows in early lactation were used in the study. The sequences of the treatments (hand-milking techniques) and the milkers
were balanced for carry-over effects between successive periods and days, respectively. The sequences were constructed by
using special Latin squares. Yield and composition of saleable milk was not affected by milking technique but there were differences
between the milkers in milk yield. There was also a significant interaction for saleable milk yield between milker and milking
technique. Hemoglobin in milk was measured as an indicator of teat damage. The hemoglobin content was numerically higher in
post-milking strip milk samples than in saleable milk. It was concluded that the amount of milk removed depends mainly on
the milker and how well the milking technique works for the individual milker. No effect of milking technique was observed
on teat treatment. 相似文献
37.
38.
A longitudinal study was done to monitor incidence of livestock diseases in ranch and pastoral herds around Lake Mburo National
Park, in South-western Uganda with a high level of wildlife (impala and zebra) and livestock (cattle and goats) interactions.
East Coast Fever (ECF), abortions, helminthosis and starvation due to drought were major livestock disease problems encountered.
ECF was a major disease affecting mainly calves, causing mortality both in ranch (8.5%) and pastoral (8.2%) herds. Meanwhile,
drought was a more serious in pastoral than ranch herds (p < 0.05), killing 28.5 % and 5.8% of adult female cattle in respective
production systems. Other endemic diseases found and controlled by vaccination were FMD, CBPP and blackquarter. In both cattle
and goats helminthosis was causing mortalities, 3.3% and 0.8% among calves in pastoral and ranches respectively; and 4.8%
and 6.9% among kids and sub-adult goats respectively. Many cases of abortions occurred among pastoral herds. In conclusion,
the disease incidence among livestock was the same or relatively low as compared to other areas without wildlife. 相似文献
39.
T. Reg Preston 《Tropical animal health and production》2009,41(7):1071-1080
Responding to the challenges posed by global warming, peak oil and biofuels will require a paradigm shift in the practice
of agriculture and in the role of live stock within the farming system. Farming systems should aim at maximizing plant biomass
production from locally available diversified resources, processing of the biomass on farm to provide food, feed and energy
and recycling of all waste materials. The approach that is the subject of this paper is that the generation of electricity
can be a by-product of food/feed production. The concept is the fractionation of biomass into inedible cell wall material
that can be converted to an inflammable gas by gasification, the gas in turn being the source of fuel for internal combustion
engines driving electrical generators. The cell contents and related structures such as tree leaves are used as human food
or animal feed. As well as providing food and feed the model is highly appropriate for decentralized small scale production
of electricity in rural areas. It also offers opportunities for sequestration of carbon in the form of biochar the solid residue
remaining after gasification of the biomass. 相似文献
40.
A cross-sectional survey was conducted in Sudan to determine sero-prevalence and risk factors associated with Neospora caninum infection in non-vaccinated dairy herds and to assess importance of the disease. Blood samples were collected from a total
of 262 animals from 25 herds. Sera were tested for antibodies against N. caninum using ELISA test. The prevalence rates of N. caninum antibodies in cattle were high both at herd level (44%) and at individual animal level (10.7%). Herd level infection rates
were similar in Khartoum State (43.7%) and at Gazira States (44.4%). The overall prevalence rates were higher (16.1%) in Gazira
State than in Khartoum State (9%) but with no significant variation. The sero-prevalence at individual animal level was significantly
higher (p < 0.05) in animals with history of abortion (12.8%) than in apparently healthy animal (11.3%), animal with history of infertility
(8.1%), or neonatal death of calves (4.3%). In addition, significantly higher (P < 0.05) sero-prevalence was observed in samples collected during the rainy season (6.87%) than winter (3.05%) or summer (0.76%).
However, no significant differences in sero-prevalence due to locality, animal breed, sex, and age were observed (p > 0.05). This preliminary study reveals for the first time the existence of natural N. caninum infection in Sudan. Also, the findings of the present study indicated that this disease is highly prevalent in two major
areas of dairy production in the country, and this calls for control strategy to be implemented. 相似文献