全文获取类型
收费全文 | 1316篇 |
免费 | 70篇 |
国内免费 | 4篇 |
专业分类
林业 | 150篇 |
农学 | 22篇 |
基础科学 | 8篇 |
267篇 | |
综合类 | 104篇 |
农作物 | 41篇 |
水产渔业 | 88篇 |
畜牧兽医 | 616篇 |
园艺 | 35篇 |
植物保护 | 59篇 |
出版年
2023年 | 7篇 |
2022年 | 13篇 |
2021年 | 20篇 |
2020年 | 20篇 |
2019年 | 23篇 |
2018年 | 37篇 |
2017年 | 46篇 |
2016年 | 42篇 |
2015年 | 23篇 |
2014年 | 41篇 |
2013年 | 79篇 |
2012年 | 70篇 |
2011年 | 82篇 |
2010年 | 46篇 |
2009年 | 52篇 |
2008年 | 60篇 |
2007年 | 73篇 |
2006年 | 56篇 |
2005年 | 82篇 |
2004年 | 43篇 |
2003年 | 59篇 |
2002年 | 33篇 |
2001年 | 45篇 |
2000年 | 29篇 |
1999年 | 36篇 |
1998年 | 13篇 |
1997年 | 8篇 |
1996年 | 12篇 |
1995年 | 27篇 |
1994年 | 13篇 |
1993年 | 8篇 |
1992年 | 17篇 |
1991年 | 8篇 |
1990年 | 11篇 |
1989年 | 16篇 |
1988年 | 13篇 |
1986年 | 11篇 |
1985年 | 9篇 |
1984年 | 4篇 |
1983年 | 8篇 |
1980年 | 7篇 |
1979年 | 7篇 |
1978年 | 5篇 |
1977年 | 6篇 |
1976年 | 5篇 |
1973年 | 6篇 |
1972年 | 5篇 |
1970年 | 4篇 |
1967年 | 9篇 |
1966年 | 9篇 |
排序方式: 共有1390条查询结果,搜索用时 15 毫秒
1.
2.
The aerobic bacterial flora of the genital tract was characterized in 15 stud dogs in an 18-month study. The dogs represented 4 breeds and were from 3 kennels. Bacterial samples from the prepuce and semen were collected every month, except in connection with matings, when they were collected weekly (464 samples). The dogs that were included all mated at least once during the study. The mean pregnancy rate, litter size, and pup mortality for the bitches with which they had mated were all within normal limits. The most frequent bacteria isolated from the prepuce and semen were Pasteurella multocida, beta-hemolytic streptococci, and Escherichia coli. There was a tendency for breeds to differ in frequency of the most common bacterial species. Bacterial culture yielded no aerobic growth in 14.2% of the preputial samples and 69.8% of the semen samples. Bacteria were transferred between dog and bitch at mating. In this study of healthy breeding dogs, neither the fertility of the dog nor that of the bitch was affected by the bacteria transferred. 相似文献
3.
4.
Endocrine effects of heat stress in boars 总被引:1,自引:0,他引:1
K. Larsson S. Einarsson K. Lundstrm J. Hakkarainen 《Acta veterinaria Scandinavica》1983,24(3):305-314
The purpose of this study was to describe the temporal changes in peripheral plasma levels of testosterone and Cortisol in boars during and after heat stress. A total of 8 boars were utilized, 4 of them were exposed to 35°C, for 100 h in a climatic room, and 4 served as controls and were kept at 20 °C for 100 h in the climatic room.Blood samples were obtained via permanent vein catheters 3 times daily from 5 days before heat stress until 20 days after termination of heat stress. Testestorone levels were determined by radioimmunoassay and Cortisol by a competitive protein binding technique.For both hormones the pre-exposure levels were similar in both groups of boars. The control boars had significantly higher testosterone levels, while being in the climatic room, than during any other period. The experimental boars had slightly increased testosterone levels during the first day of heat stress and thereafter continuously decreased levels. In the control boars the testosterone levels returned to pre-exposure levels immediately after removal from the climatic room, whereas in the experimental boars the testosterone levels were dramatically increased during the first 5 days after exposure. The differences in Cortisol levels, between the 2 groups of boars were restricted to the period spent in the climatic room. During this period the experimental boars had significantly higher Cortisol levels.Key words: boars, heat stress, testosterone, cortisol 相似文献
5.
6.
G Zamaratskaia J Babol A Madej EJ Squires K Lundström 《Reproduction in domestic animals》2004,39(3):168-172
This study describes the age-related variation in boar taint compounds, skatole and androstenone, and testosterone, oestradiol-17 beta (E17 beta), oestrone sulphate (ES), dehydroepiandrosterone sulphate (DHEAS), triiodothyronine (T(3)) and insulin-like growth factor-1 (IGF-1) in six boars. Three pairs of littermates of crossbred entire male pigs (from three Yorkshire x Duroc dams and one Hampshire sire) were included. Blood samples were taken at the age of 9-15 weeks and thereafter at weekly intervals from the age of 20-32 weeks. Plasma concentrations of skatole, androstenone, testosterone, E17 beta, ES, DHEAS, T(3) and IGF-1 were measured. We found that skatole levels in boars increased at the age around puberty after an increase in the levels of testicular steroids. Levels of skatole were not associated with the levels of sex steroids, T(3) and IGF-1. However, the increased level of testicular steroids is probably the underlying factor needed for high skatole levels to occur although the specific mechanism leading to increased skatole levels remains unknown. 相似文献
7.
D Gavier-Widén M N?remark S Benestad M Simmons L Renstr?m B Bratberg M Elvander C H?rd af Segerstad 《Journal of veterinary diagnostic investigation》2004,16(6):562-567
Within the framework of the active surveillance for transmissible spongiform encephalopathies in sheep in Sweden, 4 cases of the atypical form of scrapie, Nor98, were identified during 2003. Nor98 is a recently recognized and poorly understood variant of scrapie, first described in Norway. The cases were positive by the rapid test (enzyme-linked immunosorbent assay). Immunohistochemical staining showed diffuse thin-granular staining of the cerebellar cortex. Western immunoblotting analysis of specimens of brain stem and cerebellum showed a light band of approximately 12 kDa. Typical scrapie was ruled out based on the confirmatory testing. The affected ewes were from 4 different flocks. They were between 7 and 9 years old. Two were of the ARQ/ARQ genotype, 1 ARR/ARQ, and 1 ARR/AHQ. Two ewes had shown ataxia, and the other 2 had no clinical signs. Whole-flock slaughter was applied, and testing of the flock mates did not reveal additional cases. Nor98 differs from typical scrapie in its epidemiology, frequency of genotypes of sheep affected, clinical signs, microscopic lesions, distribution of scrapie prion protein in the brain, and characteristics of the immunostaining and immunoblotting profiles. 相似文献
8.
Effects of oral supplementation of probiotic strains of Lactobacillus rhamnosus and Enterococcus faecium on diarrhoea events of foals in their first weeks of life 下载免费PDF全文
Christina Ströbel Elena Günther Vladimir Urubschurov Annette Zeyner 《Journal of animal physiology and animal nutrition》2018,102(5):1357-1365
Foal first diarrhoea is one of the most prominent problems in the early life of horses. Probiotics might have the potency to prevent or at least diminish neonatal diarrhoea. We hypothesised that the treatment of foals with probiotic strains of Lactobacillus rhamnosus and Enterococcus faecium starting early after birth and then daily over 2 weeks would prevent or mitigate foal heat diarrhoea. The influence of this probiotic treatment on diarrhoea incidence and growth and health performance of young foals was investigated. Thirty‐four foals were randomly allocated to two groups. From day 1 to 14 of life, the foals received either placebo (PG, n = 16) or the probiotic treatment (TG, n = 18). Clinical examination was performed, and the faeces consistency score (FCS, 1–5; with diarrhoea defined by ≤3) was recorded once per day in weeks 1 and 2 and once weekly in weeks 3–8 of life (WL). The body height was measured at birth and after two and eight WL. Diarrhoea occurred in the 1st WL in 19% and 61% of PG and TG foals respectively. In the 1st WL, diarrhoea lasted 0.3 ± 0.8 and 1.6 ± 1.4 days in PG and TG foals respectively. In the 2nd WL, diarrhoea occurred in 94% and 84% of PG and TG foals, respectively, and lasted for 3.0 ± 1.5 and 3.7 ± 1.6 days respectively. At least two periods of diarrhoea developed in 33% and 65% of PG and TG foals respectively. The TG foals grew slightly slower than the PG foals. The results indicated that the probiotic treatment of neonatal foals as performed in this study was not suitable to reduce diarrhoea within the first two WL, because contrary to the hypothesis, the TG foals suffered more frequently and for longer periods from diarrhoea than the PG foals. 相似文献
9.
10.
Stina Fjelkner-Modig Håkan Bengtsson Stig Nystrõm Rolf Stegmark 《Acta Agriculturae Scandinavica, Section B - Plant Soil Science》2013,63(3):102-113
In a six-year crop rotation trial organically and integrated grown vegetables were produced according to current good agricultural practices, taking quality and quantity aspects into consideration. The raw materials assessed focussed on materials used for industrial food production. Nutritional, sensory and agricultural aspects were evaluated. Carrot, cabbage, onion, pea and potato are possible to grow organically for industrial purposes. Depending on crop, the yield was lower (65-90%) for organically grown compared to integrated grown. Cultivation of organic spinach and dill turned out to be difficult due to problems with weed and discoloration. The chemical analyses included pesticide residues, nitrate, glycoalkaloid, dry matter, vitamin C and 25 different minerals and trace elements. Overall, the organically grown crops had higher dry matter content than the integrated grown. However, when examining the data for the different crops contradictory results were noted. No significant differences due to growing system were noticed for vitamin C and the other nutrients except for 4 of the trace elements. The growing system did not influence the sensory properties. 相似文献