全文获取类型
收费全文 | 16380篇 |
免费 | 0篇 |
专业分类
林业 | 3620篇 |
农学 | 1293篇 |
基础科学 | 137篇 |
2729篇 | |
综合类 | 706篇 |
农作物 | 2095篇 |
水产渔业 | 1778篇 |
畜牧兽医 | 1050篇 |
园艺 | 1110篇 |
植物保护 | 1862篇 |
出版年
2018年 | 2745篇 |
2017年 | 2702篇 |
2016年 | 1178篇 |
2015年 | 63篇 |
2014年 | 14篇 |
2013年 | 5篇 |
2012年 | 788篇 |
2011年 | 2122篇 |
2010年 | 2101篇 |
2009年 | 1252篇 |
2008年 | 1311篇 |
2007年 | 1574篇 |
2006年 | 28篇 |
2005年 | 96篇 |
2004年 | 100篇 |
2003年 | 150篇 |
2002年 | 58篇 |
2001年 | 4篇 |
2000年 | 40篇 |
1995年 | 1篇 |
1993年 | 12篇 |
1992年 | 7篇 |
1990年 | 1篇 |
1989年 | 5篇 |
1988年 | 11篇 |
1987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 13 毫秒
41.
Shahbazfar AA Mardjanmehr SH Arab HA Rassouli A Abdollahi M 《Tropical animal health and production》2011,43(4):843-849
Artemisinin has been used for centuries to treat malaria, intestinal tract helminthosis, diarrhea, and used as an antipyretic
and sedative agent, but the usage in veterinary medicine is a new field. Recently, it has been used successfully to control
experimental poultry coccidiosis. The present study aimed to determine the effects of different doses of artemisinin in broiler
chickens with chronic usage. Sixty birds divided into one control and four treatment groups that fed rations mixed with artemisinin
at doses of 17, 34, 68, and 136 ppm for 36 days. During the experiment, birds showed no clinical signs except anemia. In microscopic
examinations, heart, lung, and spleen had no lesion, but liver, kidney, and brain showed various lesions. Degenerative lesions
like intracytoplasmic eosinophilic inclusions were seen in both kidney and liver but fatty change was seen only in liver.
There was no relationship between severity of the liver lesions and drug dosage. Central chromatolysis, scattered neuronal
necrosis, and mild spongy changes were observed in five regions of the brain that were chosen for sectioning (motor cortex,
cerebellar nuclei, midbrain nuclei, and hindbrain nuclei at two separate levels). Severity of lesions in brain was dose-dependent,
and cerebral cortex was the most vulnerable area. Haematologic tests showed lower values for hematocrit and red blood cell
count dose-dependently. In conclusion, artemisinin is a promising drug for prevention and control of coccidiosis in broiler
chickens and its side effects are not too much serious especially at therapeutic doses. 相似文献
42.
Brucellosis caused by Brucella abortus in domestic water buffaloes (Bubalus bubalis) raised under the traditional system of husbandry in northern India was diagnosed using an enzyme-linked immunosorbent assays
(ELISA) with a Protein-G-based indicator system (Protein-G ELISA). A total of 1,551 animals that are positive (N = 61), negative (N = 243), and suspected (N = 1,247) for brucellosis were examined. Rose bengal test (RBT) was used to predict the disease, and accordingly, animals
were dichotomized in positive and negative population for receiver operating characteristic (ROC) curve analysis to determine
the sensitivity, the specificity, and the performance index of Protein-G ELISA. Taking all animals (N=1551) into account, the ROC curve analysis revealed cut off value of 29.6% positivity (%P) with 98.40% and 94.94%, sensitivity
and specificity, respectively. The results were compared with ELISA in which anti-bovine conjugate was used. The cut off in
ELISA was 37.9%P and sensitivity and specificity were 96.26% and 97.07%, respectively. The performance indexes of both the
assays were almost equal and were 193.34 for Protein-G ELISA and 193.33 for ELISA. The cut off values of both the tests changed,
if only known positive (N = 61) and known negative (N=243) animals were used for ROC curve analysis, and accordingly, changes in sensitivity and specificity were observed with
significant decrease of performance indexes of both the tests. The high optical density (P<0.0001) background signal with negative serum control and high %P (P<0.0001) in sera from negative population were noticed in ELISA in comparison to Protein-G ELISA. 相似文献
43.
Nagamine MK Sanches DS Pinello KC Torres LN Mennecier G Latorre AO Fukumasu H Dagli ML 《Veterinary research communications》2011,35(6):391-399
Mast cell tumor (MCT) is one of the most prevalent neoplasms that affect skin and soft tissue in dogs. Because mast cell tumors
present a great variety of clinical appearance and behavior, their treatment becomes a challenge. Trichostatin A (TSA), an
antifungal antibiotic, has shown inhibitory effects on the proliferation and induction of apoptosis in various types of cancer
cells. In order to evaluate the potential of trichostatin A as a therapeutic drug, cells of grade 3 MCT were cultured and
treated with concentrations of 1 nM to 400 nM of TSA. MTT assay and trypan blue exclusion assays were performed to estimate
cell growth and cell viability, and cell cycle analysis was evaluated. TSA treatment showed a reduction in numbers of viable
cells and an increase of cell death by apoptosis. The cell cycle analysis showed an increase of hypodiploid cells and a reduction
of G0/G1 and G2/M –phases. According to these results, trichostatin A may be an interesting potential chemotherapeutic agent
for the treatment of canine MCT. 相似文献
44.
Characterization of Doayo and Kapsiki taurine cattle breeds of Cameroon in their natural environment
Data were collected on live weight (LW), heart girth (HG), height-at-withers (HW), trunk length (TL), age, sex, and coat color
of 207 taurines cattle—122 of the Doayo (Namchi) breed and 85 of the Kapsiki (Kirdi) breed. The animals, aged 1 to 20 years,
were selected from 60 herds randomly selected from villages of Poli of Faro and Mokolo of Tsanga, divisions of the North and
Far North Regions of Cameroon. The data were analyzed using the SAS program with a linear model, applying standard tests.
Results indicated no breed effect (P > 0.05) in the growth trends of LW, HG, HW, and TL. HG and TL were highly significantly (P < 0.0001) related to LW. The growth pattern for the two breeds was the same since the linear contrast of least square means
for the traits at various age groups did not differ (P > 0.05) significantly. The breeds attained maturity as from 4 years. In the absence of breed effect (P > 0.05), a single regression equation was established for the estimation of live weight as thus LW = - 244.42 ( ±22.57 ) kg + 2.49 ( ±0.23 ) HG + 1.04 ( ±0.25 ) TL {\hbox{LW}} = - {244}.{42 }\left( {\pm {22}.{57}} \right){\hbox{ kg}} + {2}.{49 }\left( {\pm 0.{23}} \right){\hbox{ HG}} + {1}.0{4 }\left( {\pm 0.{25}} \right){\hbox{ TL}} , with HG contributing up to 70% of total variation and TL, 2%. This equation could be used to develop a measuring band useful
in the rural environment for commercial and clinical veterinary purposes. 相似文献
45.
The consumption of solid feed is essential for successful transition from a pre-ruminant to a functional digestive tract. Lambs fed starter rations containing highly fermentable carbohydrates often experience dramatic changes in concentrations of rumen and blood metabolites. The optimal amount of roughage required in the diet of pre-ruminant animals is still unclear. The objective of this study was to determine the effect of feeding alfalfa hay on performance and rumen development in young Balouchi lambs. In a completely randomized design, 30 lambs were fed one of three experimental diets consisting of a control, without alfalfa hay (C), a diet containing 7.5% alfalfa hay (A1), and a diet containing 15% alfalfa hay (A2). Lambs fed A1 and A2 diets had lower dry matter intake during the pre-weaning period (P?0.01) and overall (P?=?0.02), but feed conversion ratio and average daily gain were not affected by feeding alfalfa hay. Concentration of beta-hydroxybutyric acid was higher in C compared with the A1 and A2 groups (P?0.01). Concentrations of glucose and non-esterified fatty acids did not differ among the groups of animals. Feeding alfalfa hay reduced thickness of the rumen epithelial keratinized layer (P?=?0.04) and increased thickness of muscular layer (P?=?0.05). We concluded that including 15% alfalfa hay in the starter diet could reduce thickness of the keratinization layer and increase muscularity of rumen wall without adverse effects on growth and performance of newborn lambs. 相似文献
46.
Oluwole Oyetunde Oni Ademola Amubieya Owoade Christopher Adeyinka Olugbenga Adeyefa 《Tropical animal health and production》2018,50(2):267-273
The use of molecular methods for rotavirus characterisation provides increased sensitivity for typing and allows the identification of putative reassortant strains. Reagents and methods for genotyping the virus need constant modification because of the reassortant nature of the virus. This study was aimed at designing and evaluating new oligonucleotide degenerate primer pairs that provide increased sensitivity and specificity for detecting avian rotavirus. Gene-specific primer pairs were designed by analysing different rotavirus strains isolated during the last decade by downloading them from the GenBank. The alignments were generated using clustal analysis from the BioEdit program. Degenerate nucleotides were included due to the reassortant nature of rotavirus. The consensus sequences were aligned using the BioEdit program and then treated with the Fast PCR software to derive the primers. The derived primer sequences were submitted for a BLAST search to ensure alignment was exclusive to the desired target genes. The designed primers had specific bands and were efficient in detecting rotavirus in faecal samples than previously published primers. Thus, a successful surveillance of rotaviruses requires that primer pairs be updated regularly in order to detect the emergence of novel or “unusual types”, which have occurred by genetic drift causing nucleotide changes at the primer binding sites that result in typing failures. We recommend the use of the proposed primers in molecular surveillance studies for efficient detection of avian rotavirus. 相似文献
47.
ObianujuNkiruka Okoroafor Paul Chekwube Eze Wilfred Sunday Ezema Chika Nwosu Christian Okorie-Kanu P. C. Animoke Boniface Anene John Osita Arinze Okoye 《Tropical animal health and production》2018,50(2):345-351
The aim of this project is to study the clinical signs and lesion of velogenic Newcastle disease (vND) in commercial turkeys, and also to find out if La Sota vaccination offered protection against these signs and lesions. The cockerels were included as positive controls. One hundred and twenty turkey poults and cockerels were divided into eight groups as follows: unvaccinated unchallenged turkeys (UUT), unvaccinated challenged turkeys (UCT), vaccinated unchallenged turkeys (VUT), vaccinated challenged turkeys (VCT), and along the same lines, the cockerel groups were UUC, UCC, VUC and vaccinated challenged cockerels (VCC). Vaccination was at 3 weeks of age while challenge was at 6 weeks of age. The unvaccinated turkeys and cockerels (UCT and UCC) showed different degrees of depression, diarrhoea and later paralysis at challenge. Total mortality was 100% in cockerels within 6 days, but 60% in turkeys. Similar but milder clinical signs were found in the VCC with a total mortality of 13.3%. The VCT showed mild drop in feed and water consumption, and no mortality. All the challenged groups had significant (p < 0.05) loss of weight when compared with their controls. Necropsy showed that while the UCC had severe proventricular haemorrhages, intestinal and caecal tonsil ulcers, the UCT had no digestive tract lesion. There was severe atrophy of the lymphoid organs in all the challenged groups. Histopathological sections of the bursa, spleen and thymus in all the challenged groups with special emphasis on the vaccinated and unvaccinated turkeys with mortalities of 0 and 60%, respectively, had very severe necrosis and depletion of the lymphoid tissue. Virus was isolated from the cloacal swabs. The haemagglutination inhibition antibodies were significantly higher (p < 0.05) in the challenged groups than the unchallenged. The above observations in the intestinal tracts of UCT are of diagnostic significance while the gross and microscopic lesions in the UCT and VCT show that La Sota vaccination may not protect turkeys against the destruction of the lymphoid organs by vND as earlier reported in chickens. This may lead to immunosuppression and production problems in areas where vND is enzootic. 相似文献
48.
Lounis Mohamed Zhao Ge Li Yuehua Gao Yubin Kaidi Rachid Oumouna Mustapha Wang Junwei Oumouna Karine 《Tropical animal health and production》2018,50(3):547-553
Avian pathogenic E. coli (APEC) is the etiologic agent of avian colibacillosis, the most common disease responsible for chicken morbidity in the world. Although multiple virulence-associated factors were identified, their prevalence in Algeria is still poorly known. In the present research, 92 avian pathogenic E. coli (APEC) isolates were recovered from broilers with clinical signs and lesions of colibacillosis. In addition, 32 E. coli isolates collected from feces of healthy birds (AFEC) were included for comparison. All isolates were investigated by PCR for the presence of a total of 11 virulence-associated genes described for avian pathogenic (iroN, ompT, hlyF, iss, iutA, and fimC) and diarrheagenic E. coli (eae, stx, elt/est, ipaH, and aggR). The sensitivity of 39 APEC isolates to 16 antibiotics was also determined using antimicrobial pretreated microplates. Here, we report that 98% of the examined isolates host at least one of the tested virulence factors. The most prevalent genes in APEC were iutA (90.6%), ompT (86.9%), and iss (85.8%); whereas, iutA (78.1%), fimC (78.1%), and iroN (68.7%) were the highest prevalent genes in AFEC. Our data showed that none of the AFEC isolates harbor any of the tested diarrheagenic genes. Moreover, only elt/est (5.4%), stx (2.1%), and ipaH (2.1%) genes were carried by APEC isolates. We further established that ceftazodime, ceftiofur, mequindox, amoxicillin/clavulanic acid, and meropenem were the most efficient antibiotics against the analyzed APEC isolates. Overall, our findings provide more insights about APEC and AFEC virulence potential in Algeria which could participate in the fight against colibacillosis. 相似文献
49.
Daniel A. Truchado Michaël A. J. Moens Sergio Callejas Javier Pérez-Tris Laura Benítez 《Veterinary research communications》2018,42(2):111-120
Papillomaviruses are non-enveloped, DNA viruses that infect skin and mucosa of a wide variety of vertebrates, causing neoplasias or simply persisting asymptomatically. Avian papillomaviruses, with six fully sequenced genomes, are the second most studied group after mammalian papillomaviruses. In this study, we describe the first oral avian papillomavirus, detected in the tongue of a dead Yorkshire canary (Serinus canaria) and in oral swabs of the same bird and other two live canaries from an aviary in Madrid, Spain. Its genome is 8,071 bp and presents the canonical papillomavirus architecture with six early (E6, E7, E1, E9, E2, E4) and two late open reading frames (L1 and L2) and a long control region between L1 and E6. This new avian papillomavirus L1 gene shares a 64% pairwise identity with FcPV1 L1, so it has been classified as a new species (ScPV1) within the Ethapapillomavirus genus. Although the canary died after showing breathing problems, there is no evidence that the papillomavirus caused those symptoms so it could be part of the oral microbiota of the birds. Hence, future investigations are needed to evaluate the clinical relevance of the virus. 相似文献
50.
Newly recorded species of the genus Isohypsibius (Tardigrada; Hypsibiidae) from China 总被引:9,自引:0,他引:9
This paper reports two newly recorded species, lsohypsibius lunulatus Iharos, 1966 and lsohypsibiusprosostomus Thulin, 1928, of the genus lsohypsibius (Tardigrada; Hypsibiidae) from China. The specimens of lsohysibius lunulatus were collected from Taibai Mt (34°18′N, 107°42′E) at 2,500 m a.s.1, and those oflsohypsibius prosostomus from Taibai Mt (34°10′N, 107°35′E) at 2,000 m above sea level. All specimens are deposited at the College of Life Sciences, Shaanxi Normal University, China. A key to the Chinese species of lsohypsibius was also given. 相似文献