全文获取类型
收费全文 | 348篇 |
免费 | 16篇 |
专业分类
林业 | 17篇 |
农学 | 13篇 |
82篇 | |
综合类 | 14篇 |
农作物 | 15篇 |
水产渔业 | 17篇 |
畜牧兽医 | 153篇 |
园艺 | 7篇 |
植物保护 | 46篇 |
出版年
2023年 | 3篇 |
2022年 | 10篇 |
2021年 | 7篇 |
2020年 | 5篇 |
2019年 | 8篇 |
2018年 | 8篇 |
2017年 | 13篇 |
2016年 | 11篇 |
2015年 | 6篇 |
2014年 | 15篇 |
2013年 | 16篇 |
2012年 | 23篇 |
2011年 | 25篇 |
2010年 | 17篇 |
2009年 | 12篇 |
2008年 | 34篇 |
2007年 | 29篇 |
2006年 | 24篇 |
2005年 | 19篇 |
2004年 | 11篇 |
2003年 | 10篇 |
2002年 | 11篇 |
2001年 | 7篇 |
2000年 | 2篇 |
1999年 | 1篇 |
1998年 | 3篇 |
1995年 | 3篇 |
1994年 | 1篇 |
1991年 | 2篇 |
1989年 | 1篇 |
1987年 | 2篇 |
1986年 | 5篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1982年 | 1篇 |
1981年 | 3篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1973年 | 2篇 |
1971年 | 2篇 |
1969年 | 2篇 |
1926年 | 1篇 |
排序方式: 共有364条查询结果,搜索用时 140 毫秒
81.
Matthew C Allender Mark A Mitchell Michael J Dreslik Christopher A Phillips Val R Beasley 《Journal of zoo and wildlife medicine》2008,39(3):358-361
At present, the hemagglutination inhibition (HI) assay is the sole commercially available serologic method available to detect exposure to ophidian paramyxovirus (OPMV) in snakes. During 2006, 26 eastern massasaugas (Sistrurus catenatus catenatus) were collected, and blood was sampled to determine their OPMV status. Samples from each snake were divided into 3 aliquots and tested by using commercially available HI assays against the 4 OPMV isolates used in the 3 laboratories that offer the service. All snakes were tested for antibodies by using HI assays against the green tree python (GTP), San Lucan rattlesnake (SLR), and Aruba Island rattlesnake (AIR) isolates. Twenty-five snakes were tested for antibodies against the western diamondback rattlesnake (WDR) isolate. All samples tested against the GTP and SLR were positive (26/26), whereas 56% (14/25) of the WDR assays were positive, and none (0/26) of the AIR assays yielded a positive result. There was 100% agreement between the GTP and SLR assays, and complete disagreement between the SLR and AIR, as well as the GTP and AIR assays. Kappa statistics for the GTP-WDR, SLR-WDR, GTP-AIR, SLR-AIR, and WDR-AIR indicated that the assays had less than chance agreement. The results demonstrate that current HI assays are not reliable as a sole diagnostic assay in the eastern massasauga. Furthermore, HI assays need to be evaluated by using other parameters to determine OPMV exposure in eastern massasaugas. 相似文献
82.
83.
We evaluated annual productivity and carbon fluxes over the Fontainebleau forest, a large heterogeneous forest region of 17,000 ha, in terms of species composition, canopy structure, stand age, soil type and water and mineral resources. The model is a physiological process-based forest ecosystem model coupled with an allocation model and a soil model. The simulations were done stand by stand, i.e., 2992 forest management units of simulation. Some input parameters that are spatially variable and to which the model is sensitive were calculated for each stand from forest inventory attributes, a network of 8800 soil pits, satellite data and field measurements. These parameters are: (1) vegetation attributes: species, age, height, maximal leaf area index of the year, aboveground biomass and foliar nitrogen content; and (2) soil attributes: available soil water capacity, soil depth and soil carbon content. Main outputs of the simulations are wood production and carbon fluxes on a daily to yearly basis. Results showed that the forest is a carbon sink, with a net ecosystem exchange of 371 g C m(-2) year(-1). Net primary productivity is estimated at 630 g C m(-2) year(-1) over the entire forest. Reasonably good agreement was found between simulated trunk relative growth rate (2.74%) and regional production estimated from the National Forest Inventory (IFN) (2.52%), as well as between simulated and measured annual wood production at the forest scale (about 71,000 and 68,000 m(3) year(-1), respectively). Results are discussed species by species. 相似文献
84.
de Freitas SN Caiaffa WT César CC Cândido AP Faria VA Neto RM Machado-Coelho GL 《Public health nutrition》2007,10(9):883-890
BACKGROUND: Obesity is defined as an excess of total body fat and may be assessed by different methods. The objective of the present study was to establish the discriminatory power of anthropometric data in determining obesity. METHODS: The subjects comprised 685 individuals, aged 20-79 years, sampled from a population-based survey. The following indicators were used: body mass index (BMI), waist circumference (WC) and total body fat percentage estimated with both Siri's equation (%BF Siri) and foot-to-foot bioelectrical impedance analysis (%BF BIA). Sensitivity and specificity of different cut-off points for each method were determined using %BF BIA as reference. RESULTS: Of 685 participants, 57.6% were aged >/= 40 years, 69.9% were women and 72.6% self-referred themselves as non-white. To classify obesity based on sex and age among women aged 0.05). Classifying according to skin colour did not change cut-off points in any indicator. CONCLUSION: BMI and WC better discriminate obesity among women and men aged >/= 40 years from a mixed-race population. 相似文献
85.
Lefebvre HP Jeunesse E Laroute V Toutain PL 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2006,20(3):499-507
Ramipril, an angiotensin-converting enzyme (ACE) inhibitor for use in dogs, is converted in vivo to its active form, ramiprilat, which is eliminated in the bile and urine in the dog. The objective of this study was to assess the effect of renal impairment on the pharmacokinetics (PKs) and pharmacodynamics (PDs) of ramipril and ramiprilat. Ten adult Beagle dogs were used. PK/PD studies were performed before and after the induction of subclinical renal impairment. Ramiprilat was given at 0.25 mg/kg by a single IV bolus. After a 2-week washout period, ramipril was administered PO at 0.25 mg/kg once daily for 8 days. Ramipril and ramiprilat PKs were studied by using a physiologically based model. The relationship between free plasma ramiprilat concentration and ACE activity was described by using the fractional Hill model. Glomerular filtration rate was decreased by 58%. No biologically relevant changes in usual plasma variables were observed between the 1st and the 8th day of oral treatment with ramipril under either condition. After an IV bolus of ramiprilat, the only changes in renal-impaired dogs were a 14 and 49% decrease in clearance of the free fraction of ramiprilat (P < .01) and free plasma concentration required to produce 50% of the maximal effect (P < .05), respectively. After repeated PO administration of ramipril, there were no alterations in any of the PK and PD parameters in healthy or renal-impaired dogs. No adjustment of the recommended PO dosage of ramipril is needed in dogs with moderate renal impairment. 相似文献
86.
The present study sought to elucidate whether Schistosoma japonicum eggs could survive a passage through dogs and chickens. Three dogs and three chickens were used for the experiment. The dogs were allowed to eat goat faeces containing 80 S. japonicum eggs per gram. The chickens were given 2 ml of water containing more than 100 S. japonicum eggs per ml. The hatchability of the eggs was 51.8% prior to administration. All faeces were collected for 3 days from the dogs and for 2 days from the chickens and egg excretion and hatchability were measured. The results showed that nearly 50% of the eggs administered to the dogs were recovered in the faeces during the first 2 days and during the first 25 h 39% of the recovered eggs were viable and able to hatch. In the chickens 9% of the administered eggs were recovered within 27 h and within the first 3.5 h after administration 19% of the recovered eggs were viable and able to hatch. The results suggest that both dogs and chickens may act as transport hosts for S. japonicum in endemic areas. 相似文献
87.
De Waele V Berzano M Speybroeck N Berkvens D Mulcahy GM Murphy TM 《Veterinary parasitology》2012,189(2-4):366-368
In order to clarify if a peri-parturient rise of Cryptosporidium parvum oocysts occurs in cows, faecal samples from 42 cows on two farms were collected. These samples were taken during the pre-parturient, the peri-parturient and the post-parturient periods. Two methods were used to detect the oocysts, a nested-PCR coupled with sequencing and a duplex real-time PCR (qPCR) that quantified Cryptosporidium spp. DNA concentration. The qPCR results were adjusted using a hierarchical Bayesian model taking into account within and between run variation. Generalised Estimating Equation models (GEE) were used to determine if peri-parturient cows were at greater risk of being infected than pre- or post-parturient cows. Fourteen dairy cows exhibited a peri-parturient and post-parturient rise in the excretion of Cryptosporidium spp. oocysts, other than the zoonotic C. parvum. The cows in the suckler beef farm were the only ones infected with the zoonotic species C. parvum at calving. Due to the low concentration of oocysts excreted mainly from species other than C. parvum, it would appear unlikely that cows act as a source of infection for their calves or contribute significantly to environmental contamination. 相似文献
88.
Cristian de la Fuente Martí Pumarola Sergio Ródenas Laia Foradada Albert Lloret Bernat Pérez de Val Sònia Añor 《Veterinary radiology & ultrasound》2012,53(6):655-659
Magnetic resonance (MR) imaging is highly sensitive for detecting tuberculomas in human patients but the specificity of the MR imaging features is low. Misdiagnosis with intracranial neoplasia is common, especially with dural‐based lesions or lesions located in the epidural space. We describe the MR imaging characteristics of an intracranial epidural tuberculoma caused by Mycobacterium tuberculosis infection in a dog. The intracranial mass and skull flat bone lysis and erosion are similar to those described in human caseating tuberculomas and can mimic intracranial neoplastic disease. 相似文献
89.
90.
Emmanuelle Muller Daniel Gargani Valérie Schaeffer Jamie Stevens Carmen Fernandez-Becerra Manuel Sanchez-Moreno Michel Dollet 《European journal of plant pathology / European Foundation for Plant Pathology》1994,100(6):425-434
Plant trypanosomatids (Phytomonas spp) have been isolated from the crude sap of coconut tress and oil palm trees affected with Hartrot or Marchitex diseases in South America andAlpinia purpurata affected with wilt in the Caribbean. They are also commonly isolated from the fruits and latex of Euphorbiaceae or Asclepiadaceae. Thirty-fourPhytomonas stocks were studied by isoenzyme electrophoresis (11 loci) in order to investigate genetic variability in the intraphloemic group. Our results showed that variability in phloem restrictedPhytomonas is very high, and that Marchitez or Hartrot associated trypanosomatids are not readily separated into two distinct groups. Moreover, the two isolates fromAlpinia are very close to the other intraphloemic isolates. The results confirm the existence of several distinct groups, comprising of at least 2 groups of phloem restricted trypanosomatids, not related to the host species, 3 groups of latex trypanosomatids, and one group of fruit trypanosomatids. 相似文献