全文获取类型
收费全文 | 1091篇 |
免费 | 57篇 |
专业分类
林业 | 95篇 |
农学 | 8篇 |
基础科学 | 7篇 |
124篇 | |
综合类 | 175篇 |
农作物 | 22篇 |
水产渔业 | 42篇 |
畜牧兽医 | 597篇 |
园艺 | 24篇 |
植物保护 | 54篇 |
出版年
2021年 | 11篇 |
2020年 | 23篇 |
2019年 | 8篇 |
2018年 | 17篇 |
2017年 | 8篇 |
2016年 | 13篇 |
2015年 | 14篇 |
2014年 | 21篇 |
2013年 | 56篇 |
2012年 | 29篇 |
2011年 | 52篇 |
2010年 | 40篇 |
2009年 | 33篇 |
2008年 | 54篇 |
2007年 | 30篇 |
2006年 | 37篇 |
2005年 | 25篇 |
2004年 | 33篇 |
2003年 | 47篇 |
2002年 | 35篇 |
2001年 | 23篇 |
2000年 | 21篇 |
1999年 | 30篇 |
1998年 | 17篇 |
1997年 | 15篇 |
1996年 | 11篇 |
1994年 | 9篇 |
1993年 | 11篇 |
1992年 | 28篇 |
1991年 | 26篇 |
1990年 | 22篇 |
1989年 | 33篇 |
1988年 | 25篇 |
1986年 | 20篇 |
1985年 | 19篇 |
1984年 | 15篇 |
1983年 | 11篇 |
1982年 | 9篇 |
1981年 | 11篇 |
1979年 | 12篇 |
1978年 | 8篇 |
1976年 | 6篇 |
1974年 | 12篇 |
1973年 | 7篇 |
1972年 | 7篇 |
1971年 | 8篇 |
1970年 | 13篇 |
1968年 | 12篇 |
1967年 | 7篇 |
1966年 | 7篇 |
排序方式: 共有1148条查询结果,搜索用时 156 毫秒
21.
Hoffmann KL Wood AK McCarthy PH Griffiths KA Evans DL Gill RW 《Anatomia, histologia, embryologia》1999,28(5-6):281-289
Investigations of the equine peripheral vascular system have been constrained by the lack of a non-invasive method of examining the arteries and veins of the limbs of the conscious horse. Precise correlations were established between the gross anatomical features of the peripheral vessels and their B-mode sonographic appearance in each thoracic limb of 35 horses. A sonographic imaging protocol was established. Additional Doppler sonographic recordings defined the arterial waveforms and demonstrated that blood flow to the foot could be evaluated in the lateral proper digital artery, distal to the level of the coronary band. Valves (with 2-4 cusps) were identified in the lumina of the medial and lateral palmar common digital veins and those of the medial and lateral palmar proper digital veins. Spontaneous echo contrast, a smoke-like haze of echoic blood, was seen in the lateral and medial palmar common digital veins, the distal deep palmar venous arch and communicating branches, and the palmar proper digital veins, and occasionally seen in the distal deep palmar arterial arch and distal proper palmar digital arteries. The value of duplex sonography (B-mode and Doppler) for anatomical and physiological studies of the peripheral vasculature of the horse was clearly established. Such data could be applied to the investigation of diseases affecting the peripheral circulation. 相似文献
22.
Relationship between skeletal muscle-specific calpain and tenderness of conditioned porcine longissimus muscle 总被引:8,自引:0,他引:8
Parr T Sensky PL Scothern GP Bardsley RG Buttery PJ Wood JD Warkup C 《Journal of animal science》1999,77(3):661-668
Tenderization of skeletal muscle in meat animals has been closely linked to the postmortem activity of the calpain proteolytic enzyme system, which includes the specific inhibitor calpastatin. Increased understanding of the skeletal muscle-specific calpain isoform p94 has prompted suggestions as to whether it too could have a role in the tenderization process. In this study, two groups of pigs were identified in which shear force measurements after 8 d of conditioning indicated a large variation in the tenderness of longissimus muscle. The quantity of p94 in the muscle was monitored by immunoblotting, using a porcine-specific polyclonal antibody raised against a recombinant peptide fragment generated as a fusion protein. The antiserum recognized a 94-kDa protein associated with myofibrils in skeletal but not cardiac muscle, as expected for this calpain isoform, although it could not be tested with the native protein because of the extreme instability of p94. In the first experiment, the mean shear force for the tough group was 6.71 +/- .28 kg (n = 12, SEM) and that of the tender group was 3.87 +/- .12 kg (n = 12), but there was no difference in the normalized absorbance of the immunopositive 94 kDa band on Western blots from samples collected at approximately 40 min postmortem. In the second experiment, the stability of p94 in chilled carcasses was investigated over 24 h, using a further two groups of 10 tough and 10 tender pigs of mean shear force values 5.36 +/- .14 kg and 2.81 +/- .15 kg, respectively. In tough and tender animals, there was a decline (P < .05) in the 94-kDa immunostaining material of mean half-lives of 13.8 and 12.9 h, respectively, although there was considerable variability. Despite this variability in half lives and shear force values, no correlation was seen between these factors. Thus, in porcine longissimus muscle, the variability in tenderness after 8 d of conditioning cannot be attributed to an underlying variability in p94. 相似文献
23.
24.
25.
SUMMARY Eleven immature adult Angiostrongylus cantonensis were recovered from beneath the meninges of a captive Bennett's wallaby (Macropus rufogriseus) which died after displaying posterior paresis followed by paralysis and intermittent opisthotonic spasms of increasing frequency for 7 days. Congestion and focal malacia with haemorrhage were seen in the brainstem and cerebellum. Sections of worms with scanty inflammatory response were seen beneath the congested haemorrhagic leptomeninges of cerebrum and in a cerebellar folium.
Infection was thought to have originated from feed or water contaminated with larvae released from a molluscan intermediate host. 相似文献
Infection was thought to have originated from feed or water contaminated with larvae released from a molluscan intermediate host. 相似文献
26.
27.
28.
29.
Foster AP Littlewood JD Webb P Wood JL Rogers K Shaw SE 《Veterinary immunology and immunopathology》2003,93(1-2):51-60
Atopic dermatitis in dogs is a common allergic skin disease that affects substantial numbers of dogs in the UK. The purpose of this study was to compare the results of an intradermal test (IDT) and an in vitro test in a large cohort of dogs. Dogs were intradermal tested with Greer allergens (Greer Labs Inc, Lenoir, NC, USA) using standard techniques. At the same time blood samples were drawn and submitted for evaluation by ELISA using the ALLERCEPT Definitive Allergen Panels for allergen-specific IgE, a commercial assay that uses a biotinylated recombinant extracellular domain of the high affinity Fc-epsilon receptor alpha chain protein (Fcepsilon RIalpha). The allergens used in the two tests included grass, tree and weed pollens, moulds, flea saliva/whole flea extract and house dust mite species. The optical density readings from the ELISA for each allergen were compared with the results of the IDT for 265 dogs. The prevalence of positive reactions in the ELISA was equal to or greater than the results of the IDT in the case of almost all of the allergens, but two notable exceptions were the house dust mites Dermatophagoides farinae and Dermatophagoides pteronyssinus. These two allergens were the most common positive reactions by IDT (prevalence D. farinae 78.9%, D. pteronyssinus 66.4%). The results of the two tests were significantly different (McNemar's test, P<0.05) for 16 of the 22 allergens. The sensitivities of the ELISA compared to the IDT (where there were more than 3 dogs with positive reactions in both tests) varied between 19.3 and 77.1% (D. pteronyssinus 19.3% and D. farinae 67.9%) and the specificities varied between 64.2 and 96.6% (D. pteronyssinus 96.6% and D. farinae 89.3%). 相似文献
30.