全文获取类型
收费全文 | 947篇 |
免费 | 57篇 |
专业分类
林业 | 10篇 |
农学 | 13篇 |
基础科学 | 3篇 |
81篇 | |
综合类 | 152篇 |
农作物 | 34篇 |
水产渔业 | 31篇 |
畜牧兽医 | 637篇 |
园艺 | 15篇 |
植物保护 | 28篇 |
出版年
2023年 | 8篇 |
2021年 | 6篇 |
2020年 | 11篇 |
2019年 | 11篇 |
2018年 | 12篇 |
2017年 | 11篇 |
2016年 | 12篇 |
2015年 | 10篇 |
2014年 | 18篇 |
2013年 | 45篇 |
2012年 | 29篇 |
2011年 | 25篇 |
2010年 | 45篇 |
2009年 | 33篇 |
2008年 | 40篇 |
2007年 | 41篇 |
2006年 | 26篇 |
2005年 | 20篇 |
2004年 | 35篇 |
2003年 | 36篇 |
2002年 | 39篇 |
2001年 | 29篇 |
2000年 | 27篇 |
1999年 | 26篇 |
1998年 | 21篇 |
1997年 | 12篇 |
1996年 | 25篇 |
1995年 | 12篇 |
1994年 | 7篇 |
1993年 | 13篇 |
1992年 | 21篇 |
1991年 | 16篇 |
1990年 | 27篇 |
1989年 | 16篇 |
1988年 | 16篇 |
1987年 | 16篇 |
1986年 | 11篇 |
1985年 | 11篇 |
1984年 | 6篇 |
1982年 | 9篇 |
1981年 | 9篇 |
1974年 | 8篇 |
1972年 | 11篇 |
1971年 | 11篇 |
1970年 | 8篇 |
1968年 | 6篇 |
1967年 | 6篇 |
1966年 | 7篇 |
1965年 | 6篇 |
1946年 | 9篇 |
排序方式: 共有1004条查询结果,搜索用时 15 毫秒
11.
Corfield GS Read RA Eastley KA Richardson JL Robertson ID Day R 《Australian veterinary journal》2007,85(6):212-216
Hip palpation has been used to provide semiquantitative information regarding passive joint laxity and susceptibility to hip dysplasia. The purpose of this study was to: (1) evaluate the intra- and inter-examiner repeatability of the hip reduction angle measured at 4 months of age by three examiners using manual goniometry and an electromagnetic tracking system; (2) compare the hip reduction angle measured with manual goniometry to the hip reduction angle measured with the electromagnetic tracking system; and (3) evaluate the hip reduction angle, distraction index and Ortolani manoeuvre at 4 months of age as predictors of the development of hip osteoarthritis at 12 months of age in 11 Labrador Retriever dogs. Intra- and inter-examiner repeatability was demonstrated for both the manual and electromagnetic goniometric measurement of the hip reduction angle (coefficient of variation < 4.3% and < 6.1%; and P = 0.163 and P = 0.836 respectively). The hip reduction angle measured by manual goniometry was moderately correlated to the hip reduction angle measured by the electromagnetic tracking system (r = 0.603, P < 0.0000). The hip reduction angle measured by manual and electromagnetic goniometry was a poor predictor of osteoarthritis at 12 months of age (r = 0.231, P < 0.062, and r = 0.321, P < 0.01). The distraction index was moderately correlated with the development of osteoarthritis by 12 months of age (r = 0.493, P < 0.0000). The Ortolani sign was sensitive (100%) but not specific (41%) for the development of osteoarthritis at 12 months of age. The hip reduction angle did not further quantify the Ortolani manoeuvre as a predictor of osteoarthritis in Labrador Retrievers. 相似文献
12.
Jefferies R Ryan UM Jardine J Broughton DK Robertson ID Irwin PJ 《Australian veterinary journal》2007,85(11):459-463
This study reports on the epidemiology of Babesia gibsoni in American Pit Bull Terriers living in a region of western Victoria in southern Australia. Both American Pit Bull Terriers (n = 100) and other dog breeds (n = 51) were screened for B gibsoni using immunofluorescent antibody testing (IFAT) and/or polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP). A questionnaire was also completed by each dog owner, ascertaining the husbandry and habits of the dogs sampled. Fourteen dogs were positive for B gibsoni using IFAT and/or PCR-RFLP and all were American Pit Bull Terriers. Dogs that were male and/or had been bitten by or were biters of other American Pit Bull Terriers were more likely to be B gibsoni positive, thus suggesting that blood-to-blood transmission contributes to the spread of this disease between dogs. 相似文献
13.
Carbohydrate composition in relation to structural stability, compactibility and plasticity of two soils in a long-term experiment 总被引:3,自引:0,他引:3
B. C. Ball M. V. Cheshire E. A. G. Robertson E. A. Hunter 《Soil & Tillage Research》1996,39(3-4):143-160
The effects of tillage on soil organic carbon content, carbohydrate content, monosaccharide composition, aggregate stability, compactibility and plasticity were investigated in a field experiment on a gleysol and on a cambisol under winter barley in South-East Scotland. Two long-term treatments (direct drilling and conventional mouldboard ploughing for 22 years) were compared with short-term direct drilling and broadcast sowing plus rotavation for 5 years. Carbohydrate released sequentially to cold water, hot water, 1.0 M HCl and 0.5 M NaOH was determined after hydrolysis as reducing sugar equivalent to glucose in both fresh and air-dried samples. All other measurements were made on dry soils only. About 3% of the soluble carbohydrate was extracted by cold water, 10% by hot water, 12% by HCl and 75% by NaOH from both the dry and fresh soils. The total reducing sugars of the fractions were proportional to the total organic carbon determined by dichromate oxidation or C analysis. Organic carbon and carbohydrates were concentrated near the surface of the direct drilled soil, but were more uniformly distributed with depth in the ploughed soil. The surface soil under direct drilling was more stable, less compactible and had greater plasticity limits than under ploughing. However, particle size distributions were unaffected by tillage so that differences in soil properties were attributed to differences in the quantity and quality of organic matter. Differences in compactibility, structural stability and plasticity limits between depths and tillage treatments correlated with total carbon and with total carbohydrates. The hot water extractable carbohydrate fraction correlated best with aggregate stability and the NaOH fraction correlated best with compactibility and plastic limit. Both fractions were greatest in the long-term direct drilled soil. The hot water fraction had a galactose plus mannose over arabinose plus xylose ratio of 1.0–1.6 in comparison to 0.4–0.7 in the NaOH fraction indicating that the microbial contribution within the hot water-soluble fraction was the greater. The hot-water fraction was likely to contain more exocellular microbial polysaccharides involved in the stabilizing of soil aggregates. The hot-water and NaOH carbohydrate fractions may be good indicators of soil organic matter quality relevant to the preservation of good soil physical conditions. 相似文献
14.
Lara D.Shepherd Alan J.D.Tennyson Hugh A.Robertson Rogan M.Colbourne Kristina M.Ramstad 《中国鸟类》2021,(2):195-207
Background: Kiwi (Apteryx spp.) are flightless ratites from New Zealand whose numbers and distributions have declined following human arrival. Some of the kiwi ... 相似文献
15.
The nature of the organic matter in the A horizons of seven New Zealand soils in tussock grasslands has been shown by pyrolysis-gas chromatography of the whole soils to be strongly influenced by climate. A ratio relating the a abundances of four pyrolysis products varies systematically from 1.20 for a brown-grey earth to 3.82 for a high-country podzolized yellow-brown earth, and shown significant correlations with altitude, precipitation, and mean annual temperature; this is in accord with the concept of the seven soils forming members of a climosequence. Similarities with the mull/mor humus sequence in Scottish soils are also noted. 相似文献
16.
Some genetic characteristics of the freely drained soils of the ettrick association in East Scotland
This paper describes the interrelated characteristics of the freely drained soil series of the Ettrick Association. These soils are extensively developed in the Southern Uplands of Scotland on glacial drift derived from greywacke.At the present day the soils of the Linhope series are acid brown soils whereas the Minchmoor and Dod series include podzols and peaty podzols. Subalpine podzols and alpine soils are included within the Merrick series. It is concluded that the soils of the Linhope, Minchmoor and Dod series were all formerly brown forest soils under deciduous woodland. They have evolved to their present status after forest clearance which gathered momentum after the widespread establishment of monastic institutions in Scotland in the twelfth and thirteenth centuries A.D. The evolutionary outline of profile development is described and discussed. 相似文献
17.
18.
Effects of ambient temperature and restricted feeding on the growth of feathers in growing turkeys 总被引:2,自引:0,他引:2
1. Male turkeys were reared to 6 weeks of age at 15 degrees C and 26 degrees C and fed ad libitum or restricted to 0.5 of the body weight of birds fed ad libitum. Basal metabolic rate was determined by indirect calorimetry at an ambient temperature of 20 degrees C. 2. Turkeys at 15 degrees C were lighter than those kept at 26 degrees C. Feather lengths and weight were similar in both groups. Fasting heat production corrected for both metabolic body size and activity was greater in turkeys reared at 15 degrees C than those at 26 degrees C. 3. Cranial breast feathers were significantly longer in restricted birds than in those fed ad libitum in contrast to a proportional decrease in the lengths of other feathers of 0.1 to 0.3. Feather weight as a proportion of body weight was 0.072 in restricted turkeys compared with 0.046 in birds fed ad libitum. There was no difference in basal metabolic rate between ad libitum and restricted turkeys. 4. It was concluded that feather growth was maintained in preference to body and muscle growth and that rearing birds at 15 degrees C did not improve breast feather cover. It is suggested that the growth of breast feathers in turkeys fed ad libitum is impaired. 相似文献
19.
Taylor PM Robertson SA Dixon MJ Ruprah M Sear JW Lascelles BD Waters C Bloomfield M 《Journal of veterinary pharmacology and therapeutics》2001,24(6):391-398
Pharmacokinetics of morphine, buprenorphine and pethidine were determined in 10 cats. Six cats received morphine (0.2 mg/kg) intravenously and four intramuscularly. Five received buprenorphine (0.01 mg/kg) intravenously and six intramuscularly. Six received pethidine (5 mg/kg) intramuscularly. Jugular venous blood samples were collected at time points to 24 h, and plasma morphine concentrations were measured by high performance liquid chromatograpy (HPLC), buprenorphine by radioimmunoassay (RIA) and pethidine by gas chromatography. Our data for morphine show elimination half-life (t1/2el) 76.3 min intravenous (i.v.) and 93.6 min intramuscular (i.m.); mean residence time (MRT) 105.0 and 120.5 min; clearance (Clp) 24.1 and 13.9 mL/kg/min; and volume of distribution (V(dss)) 2.6 and 1.7 L/kg, respectively. Comparable data for buprenorphine are t1/2el 416.8 and 380.2 min; MRT 417.6 and 409.8 min; Clp 16.7 and 23.7 mL/kg/min; and V(dss) 7.1 and 8.9 L/kg. For i.m. pethidine, t1/2el 216.4 min; MRT 307.5 min; Clp 20.8 mL/kg/min and V(dss) 5.2 L/kg. For i.m. dosing, the tmax for morphine, buprenorphine and pethidine were 15, 3 and 10 min, respectively. The pharmacokinetics of the three opioids in cats are broadly comparable with those of the dog, although there is a suggestion that the cat may clear morphine more slowly. 相似文献
20.
Hrubec TC Smith SA Robertson JL 《Veterinary clinical pathology / American Society for Veterinary Clinical Pathology》2001,30(1):8-15
Hybrid striped bass (Morone chrysops X Morone saxatilis ) are an important aquaculture species yet there are few diagnostic tools available to assess their health. Hematology and clinical chemistry analyses are not used extensively in fish medicine due to the lack of reference intervals for various fish species, and because factors such as age can affect blood values. There is little published information regarding age-related changes in blood values of juvenile fish. It is important to evaluate juvenile fish, as this is the time they are raised in aquaculture settings. Determining age-related changes in the blood values of fishes would further develop clinical pathology as a diagnostic tool, enhancing both fish medicine and the aquaculture industry. The results of standard hematology and clinical chemistry analysis were evaluated in juvenile hybrid striped bass at 4, 6, 9, 15, and 19 months of age. Values for PCV and RBC indices were significantly lower, and plasma protein concentration was significantly higher in younger fish. Total WBC and lymphocyte counts were significantly higher in fish at 6 and 9 months of age, while neutrophil and monocyte counts were higher at 6, 9, and 15 months. Eosinophil counts were significantly higher in 9-month-old fish. The majority of hematologic values fell within previously established reference intervals, indicating that only slight modification to the intervals is necessary for evaluating hematologic results of hybrid striped bass at different ages. The following analytes deviated sufficiently from adult reference intervals to warrant separate reference values: plasma protein concentration at 4 months, WBC and lymphocyte counts at 15 and 19 months, and thrombocyte-like-cells at 9 months of age. Values for most biochemical analytes were significantly different among age groups except for creatinine and potassium concentrations. Comparisons with reference intervals were not made for biochemical analytes, because established reference intervals were not available. Age-related changes in hematologic and biochemical values of striped bass were similar to those reported for rainbow trout and mammals. 相似文献