全文获取类型
收费全文 | 18118篇 |
免费 | 101篇 |
专业分类
林业 | 3757篇 |
农学 | 1356篇 |
基础科学 | 145篇 |
3278篇 | |
综合类 | 790篇 |
农作物 | 2185篇 |
水产渔业 | 1927篇 |
畜牧兽医 | 1600篇 |
园艺 | 1142篇 |
植物保护 | 2039篇 |
出版年
2023年 | 24篇 |
2022年 | 38篇 |
2021年 | 60篇 |
2020年 | 75篇 |
2019年 | 80篇 |
2018年 | 2780篇 |
2017年 | 2751篇 |
2016年 | 1244篇 |
2015年 | 123篇 |
2014年 | 97篇 |
2013年 | 153篇 |
2012年 | 908篇 |
2011年 | 2284篇 |
2010年 | 2171篇 |
2009年 | 1322篇 |
2008年 | 1432篇 |
2007年 | 1678篇 |
2006年 | 127篇 |
2005年 | 177篇 |
2004年 | 167篇 |
2003年 | 208篇 |
2002年 | 119篇 |
2001年 | 16篇 |
2000年 | 57篇 |
1999年 | 15篇 |
1998年 | 7篇 |
1997年 | 11篇 |
1996年 | 7篇 |
1995年 | 1篇 |
1994年 | 6篇 |
1993年 | 15篇 |
1992年 | 11篇 |
1991年 | 3篇 |
1990年 | 5篇 |
1989年 | 6篇 |
1988年 | 16篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1984年 | 2篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1980年 | 1篇 |
1977年 | 4篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1972年 | 1篇 |
1971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.
Claudio Bussadori DVM DECVIM Oriol Domenech DVM Antonio Longo DVM Danitza Pradelli DVM Roberto Bussadori DVM 《Journal of Veterinary Cardiology》2002,4(2)
A 6-months old female German shepherd dog was referred for management of congenital heart disease. A diagnosis of pulmonic stenosis (PS) and patent ductus arteriosus (PDA) was confirmed by Doppler echocardiography and cardiac catheterisation. The conditions were treated during a single cardiac catheterisation procedure using percutaneous techniques. Gianturco coil embolisation was used to close the PDA, and the PS was relieved using a balloon valvuloplasty technique. 相似文献
52.
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
53.
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
54.
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
55.
Denis M Lacy-Hulbert SJ Buddle BM Williamson JH Wedlock DN 《Veterinary research communications》2011,35(3):145-156
The presence, phenotype and function of Streptococcus uberis-specific T cells in the mammary gland secretion (MGS) and blood of cows exposed to S. uberis were assessed. MGS T cells in the udder were purified and incubated with autologous blood monocytes as antigen-presenting
cells (APC). Most cows, irrespective of prior S. uberis infection status and lactation status, were shown to have S. uberis-specific T cells both in MGS and in the blood. When cells from a subgroup of cows were studied, it was found that the S. uberis-specific T cells produced high levels of interferon-gamma (IFN-γ), but low levels of interleukin-10 (IL-10). A high percentage
of responding T cells were of the CD8
+
memory (CD45RO) subset. T cells from the MGS specific for S. uberis were propagated from animals during the drying off period and expanded in vitro using interleukin-2 (IL-2) and S. uberis antigens. This led to the accumulation of T cells of the CD8
+
subset bearing memory cell markers (CD45A
−
, CD45RO
+
), which released high levels of IFN-γ. Four of the five T cell lines derived from the MGS of three animals had substantial
direct killing activity towards S. uberis in vitro. It is concluded that there is an emergence of S. uberis-specific bactericidal T cells in the MGS of cows after infection or environmental exposure to S. uberis. Vaccines aimed at activating and expanding this T cell population in the mammary glands of cattle may offer an avenue for
the prevention of mastitis caused by S. uberis. 相似文献
56.
Ornithobacterium rhinotracheale is a gram negative bacterial pathogen causing respiratory tract infections in poultry. Tracheal, lung and serum samples were
obtained from 21 broiler flocks of 8 farms from a slaughterhouse located in south-eastern of Iran. Among 630 tracheal and
lung samples from samples resulting from 315 chickens, 11 (3.5%) ORT isolates were identified using biochemical tests. The
isolates originated from 9 (42.9%) flocks out of 4 farms. All of the isolates were recovered from tracheal swabs and showed
an API 20NE identification biocode 0-2-2-0-0-0-4. Of the 420 serum samples examined by ELISA, 134 (31.9%) sera from 17 (81.0%)
flocks were positive for ORT antibodies. These results indicate that ORT is present in most broiler flocks with respiratory
disorders in southeast Iran. 相似文献
57.
Santosh Kumar Subodh Kumar Vijay Kumar Kaushal K. Singh Birendra K. Roy 《Veterinary research communications》2009,33(8):887-893
The present experiment was designed to study the pharmacokinetics of levofloxacin in six healthy cross bred female cow calves (4 to 6 months age) weighing between 40 to 80 kg. Plasma from blood was separated by centrifugation at 10,000 rpm. Quantitative estimation of levofloxacin was done by UV-VIS spectrophotometer at 286 nm. The mean maximum plasma concentration (Cpmax ) of levofloxacin in febrile calves (5.28?±?0.32 µg/ml) did not differ significantly as compared with healthy calves (4.50?±?0.22 µg/ml) after single dose (20 mg/kg) oral administration. The mean therapeutic plasma concentration ( Cpther ) of levofloxacin was maintained for longer period in febrile calves (10 h) as compared to healthy calves ( 8 h). The mean maximum urine concentration (Cumax) in febrile (40.86?±?2.19 µg/ml) also did not differ significantly as compared with healthy calves (39.38?±?2.43 µg/ml). No significant difference in various pharmacokinetic parameters of plasma was observed in healthy calves ( β?=?0.23?±?0.01/h ; t1/2 β?=?3.00?±?0.17 h and MRT?=?4.66?±?0.14 h ) and febrile calves ( β?=?0.23?±?0.01/ h; t1/2 β?=?3.05?±?0.16 h and MRT?=?5.04?±?0.14 h ) . The mean value of β, and t ½ β calculated in urine also did not differ between healthy and febrile calves. However, the value of MRT(3.79?±?0.07 h) and ClB(1.65?±?0.09 ml/kg/min) calculated in urine of febrile calves significantly(p?0.05) differ to healthy calves(MRT?=?3.15?±?0.03 h;ClB?=?2.09?±?0.13 ml/kg/min). Based on kinetic profile levofloxacin may be given orally at the dose rate of 1.49 mg/kg B.W.at 8 h intervals in febrile calves. 相似文献
58.
García-Bocanegra I Arenas-Montes A Lorca-Oró C Pujols J González MA Napp S Gómez-Guillamón F Zorrilla I Miguel ES Arenas A 《Veterinary research》2011,42(1):88
ABSTRACT: Although the importance of wild ruminants as potential reservoirs of bluetongue virus (BTV) has been suggested, the role played by these species in the epidemiology of BT in Europe is still unclear. We carried out a serologic and virologic survey to assess the role of wild ruminants in the transmission and maintenance of BTV in Andalusia (southern Spain) between 2006 and 2010.A total of 473 out of 1339 (35.3%) wild ruminants analyzed showed antibodies against BTV by both ELISA and serum neutralization test (SNT). The presence of neutralizing antibodies to BTV-1 and BTV-4 were detected in the four species analyzed (red deer, roe deer, fallow deer and mouflon), while seropositivity against BTV-8 was found in red deer, fallow deer and mouflon but not in roe deer. Statistically significant differences were found among species, ages and sampling regions. BTV RNA was detected in twenty-one out of 1013 wild ruminants (2.1%) tested. BTV-1 and BTV-4 RNA were confirmed in red deer and mouflon by specific rRT-PCR.BTV-1 and BTV-4 seropositive and RNA positive wild ruminants, including juveniles and sub-adults, were detected years after the last outbreak was reported in livestock. In addition, between the 2008/2009 and the 2010/2011 hunting seasons, the seroprevalence against BTV-1, BTV-4 and BTV-8 increased in the majority of provinces, and these serotypes were detected in many areas where BTV outbreaks were not reported in domestic ruminants. The results indicate that wild ruminants seem to be implicated in the dissemination and persistence of BTV in Spain. 相似文献
59.
Cryptosporidiosis in buffalo calves (<Emphasis Type="Italic">Bubalus bubalis</Emphasis>): Prevalence and potential risk factors 总被引:1,自引:0,他引:1
The objective of the present study was to describe the prevalence and risk factors associated with cryptosporidiosis in buffalo calves in Middle Egypt. During one year, 458 fecal samples were collected from buffalo calves less than 3 month age in 55 small scale herds and examined for the presence of Cryptosporidium oocysts. Data describing age, gender, season, and herd management practices were gathered to assess potential risk factors. Fecal examination showed that 14.19% of the examined calves were positive for Cryptosporidium spp. Calves at 1-15 days were at the highest risk (P < 0.001), and a significant relationship between season and infection (P < 0.05) was recorded. A significant association between infection and hygiene (P < 0.001), type of floor (P < 0.01) and source of water (P < 0.01) was also recorded. Statistical analysis concerning the clinical signs and fecal characteristics revealed a significant association with fecal consistency (P < 0.001), presence of blood (P < 0.01) and mucous (P < 0.01). Moreover, a significant association was found between infection and the desire for suckling (P < 0.05) and tenesmus (P < 0.05). The results of the present study demonstrated the strong relation between infections by Cryptosporidium spp. and diarrhea in buffalo calves. 相似文献
60.
María Llarena-Reino Carmen Piñeiro José Antonio Luis Outeriño Carlos Vello Ángel F. González Santiago Pascual 《Veterinary parasitology》2013,191(3-4):276-283
During the last 50 years human anisakiasis has been rising while parasites have increased their prevalence at determined fisheries becoming an emergent major public health problem. Although artificial enzymatic digestion procedure by CODEX (STAN 244-2004: standard for salted Atlantic herring and salted sprat) is the recommended protocol for anisakids inspection, no international agreement has been achieved in veterinary and scientific digestion protocols to regulate this growing source of biological hazard in fish products. The aim of this work was to optimize the current artificial digestion protocol by CODEX with the purpose of offering a faster, more useful and safer procedure for factories workers, than the current one for anisakids detection. To achieve these objectives, the existing pepsin chemicals and the conditions of the digestion method were evaluated and assayed in fresh and frozen samples, both in lean and fatty fish species. Results showed that the new digestion procedure considerably reduces the assay time, and it is more handy and efficient (the quantity of the resulting residue was considerably lower after less time) than the widely used CODEX procedure. In conclusion, the new digestion method herein proposed based on liquid pepsin format is an accurate reproducible and user-friendly off-site tool, that can be useful in the implementation of screening programs for the prevention of human anisakiasis (and associated gastroallergic disorders) due to the consumption of raw or undercooked contaminated seafood products. 相似文献