全文获取类型
收费全文 | 557篇 |
免费 | 24篇 |
国内免费 | 2篇 |
专业分类
林业 | 20篇 |
农学 | 4篇 |
基础科学 | 3篇 |
68篇 | |
综合类 | 85篇 |
农作物 | 12篇 |
水产渔业 | 14篇 |
畜牧兽医 | 349篇 |
园艺 | 3篇 |
植物保护 | 25篇 |
出版年
2020年 | 6篇 |
2019年 | 4篇 |
2018年 | 4篇 |
2017年 | 5篇 |
2016年 | 4篇 |
2015年 | 6篇 |
2014年 | 8篇 |
2013年 | 9篇 |
2012年 | 19篇 |
2011年 | 22篇 |
2010年 | 8篇 |
2009年 | 18篇 |
2008年 | 24篇 |
2007年 | 29篇 |
2006年 | 21篇 |
2005年 | 22篇 |
2004年 | 28篇 |
2003年 | 25篇 |
2002年 | 26篇 |
2001年 | 20篇 |
2000年 | 25篇 |
1999年 | 18篇 |
1997年 | 3篇 |
1996年 | 12篇 |
1995年 | 4篇 |
1994年 | 12篇 |
1993年 | 8篇 |
1992年 | 11篇 |
1991年 | 5篇 |
1990年 | 6篇 |
1989年 | 13篇 |
1988年 | 15篇 |
1987年 | 6篇 |
1986年 | 5篇 |
1985年 | 8篇 |
1984年 | 10篇 |
1983年 | 9篇 |
1980年 | 5篇 |
1979年 | 10篇 |
1978年 | 3篇 |
1976年 | 5篇 |
1975年 | 3篇 |
1973年 | 4篇 |
1971年 | 3篇 |
1969年 | 4篇 |
1968年 | 5篇 |
1967年 | 4篇 |
1963年 | 3篇 |
1962年 | 4篇 |
1926年 | 3篇 |
排序方式: 共有583条查询结果,搜索用时 71 毫秒
1.
Aerobic bacterial populations were studied on the distal hair coat and at the skin surface of the shoulder, rump and abdomen of 10 healthy dogs. Coagulase negative staphylococci (CNS) were more frequently isolated from the hair than the skin at the shoulder and rump. There was no difference in the isolation rate of coagulase positive staphylococci (CPS) (Staphylococcus intermedius) between the hair and skin. Total skin counts were greatest on the abdomen whereas CNS counts from the hair were least at this site. There were no differences between CPS counts at the three sites on either hair or skin. The populations on the relatively unfavourable microenvironment of the distal hair may represent contamination rather than colonisation. The low populations of CPS at the skin surface also indicate contamination or transient colonisation rather than true resident status. 相似文献
2.
L Reeve-Johnson 《The Veterinary record》2001,149(18):549-552
Respiratory disease was induced in 16 calves, and the terminal clinical signs of disease and postmortem pathological observations were recorded. By Spearman's correlation coefficient, the respiratory rate, rectal temperature and clinical scores of the calves were significantly correlated with the extent of lung consolidation. The respiratory rate was the clinical sign most consistently correlated with the other clinical and pathological signs of respiratory disease. 相似文献
3.
Chloroform-methanol (2:1 v/v), absolute methanol, and 90% acetone were evaluated for their effectiveness as extractants of chlorophyll a from samples of phytoplankton communities collected from catfish ponds. Chloroform-methanol consistently extracted more chlorophyll a than either 90% acetone or methanol. Precision for the methanol extraction was also unacceptably low, with an average coefficient of variation of 17%. Average coefficients of variation for the chloroform-methanol and 90% acetone extraction procedures were 6 and 5%, respectively. Filtered samples should be steeped in chloroform-methanol for at least 4 h to obtain maximum chlorophyll extraction, and the addition of MgCO3 to the extractant as a buffer is not necessary. 相似文献
4.
Michael R. Metcalf DVM MS Lloyd P. Tate DVM Loouis C. Sellett MS 《Veterinary radiology & ultrasound》1989,30(2):80-87
5.
The stratum corneum measured on fresh frozen sections was found to be considerably thicker than previously reported. It was uniformly permeated with sebum, which also formed an intact film over the skin surface and it could readily be divided into two zones. The living epidermis was approximately half as thick as the stratum corneum. 相似文献
6.
Summary Airborne measurements of reflected solar and emitted thermal radiation were combined with ground-based measurements of incoming solar radiation, air temperature, windspeed, and vapor pressure to calculate instantaneous evaporation (LE) rates using a form of the Penman equation. Estimates of evaporation over cotton, wheat, and alfalfa fields were obtained on 5 days during a one-year period. A Bowen ratio apparatus, employed simultaneously, provided ground-based measurements of evaporation. Comparison of the airborne and ground techniques showed good agreement, with the greatest difference being about 12% for the instantaneous values. Estimates of daily (24 h) evaporation were made from the instantaneous data. On three of the five days, the difference between the two techniques was less than 8%, with the greatest difference being 25%. The results demonstrate that airborne remote sensing techniques can be used to obtain spatially distributed values of evaporation over agricultural fields. 相似文献
7.
8.
Huwyler U Reeve-Johnson L Korfitsen J Liesegang A Wanner M 《Schweizer Archiv für Tierheilkunde》1999,141(4):203-208
A trial was carried out on a beef cattle farm to obtain efficacy data for the treatment of naturally occurring bronchopneumonia in calves under commercial production conditions. The treatment was administered by medicating milk with three different tilmicosin doses mixed in the first 80% of the daily milk ration. According to the clinical results, all three treatment regimens proved to be effective. The efficacies of the reduced dose of 12.5 mg tilmicosin/kg body weight daily for 5 days and of the reduced treatment duration with 25 mg/kg b.w. daily for 3 days were equivalent to a previously proven dose of 25 mg/kg b.w. daily for 5 days. 相似文献
9.
10.
Byron CR Orth MW Venta PJ Lloyd JW Caron JP 《American journal of veterinary research》2003,64(6):666-671
OBJECTIVE: To characterize potential mechanisms of action of glucosamine inhibition of matrix metalloproteinase (MMP) expression and activity in lipopolysaccharide (LPS)-stimulated equine chondrocytes. SAMPLE POPULATION: Chondrocytes cultured from samples of metacarpophalangeal articular cartilage collected from cadaveric limbs of horses. PROCEDURE: The effect of glucosamine on MMP activity in conditioned medium from LPS-stimulated cartilage explants was determined by a colorimetric assay with azocoll substrate. Treatments consisted of negative and positive controls, glucose (50 mM), and glucosamine (50, 25, 6.25, 3, and 1.5 mM). The influence of glucosamine on MMP synthesis was determined in chondrocytes in pellet culture incubated with LPS (20 microg/mL). Concentration of MMP-13 was quantified in spent medium via ELISA; nonspecific MMP activity was determined via azocoll digestion in organomercurial-activated medium. Effects of glucosamine on MMP mRNA concentration in similarly treated chondrocytes were determined by northern blot hybridization with MMP-1, -3, and -13 probes. Statistical analyses were performed with 2-way ANOVA. RESULTS: Glucosamine had no effect on activated MMP activity but inhibited MMP protein expression, as determined by azocoll digestion (glucosamine, 3 to 50 mM) and MMP-13 ELISA (glucosamine, 1.5 to 50 mM). Resting mRNA concentrations for MMP-1, -3, and -13 mRNA were significantly lower in cultures exposed to glucosamine at concentrations of 50 and 25 mM than those of positive controls. CONCLUSIONS AND CLINICAL RELEVANCE: Glucosamine appears capable of pretranslational, and possibly also translational, regulation of MMP expression; data suggest a potential mechanism of action for chondroprotective effects of this aminomonosaccharide. 相似文献