全文获取类型
收费全文 | 165929篇 |
免费 | 9505篇 |
国内免费 | 14642篇 |
专业分类
林业 | 11813篇 |
农学 | 9036篇 |
基础科学 | 7870篇 |
16888篇 | |
综合类 | 77446篇 |
农作物 | 11658篇 |
水产渔业 | 6982篇 |
畜牧兽医 | 28166篇 |
园艺 | 12357篇 |
植物保护 | 7860篇 |
出版年
2024年 | 1151篇 |
2023年 | 3076篇 |
2022年 | 7404篇 |
2021年 | 7297篇 |
2020年 | 6667篇 |
2019年 | 6549篇 |
2018年 | 4830篇 |
2017年 | 7718篇 |
2016年 | 5092篇 |
2015年 | 7760篇 |
2014年 | 8201篇 |
2013年 | 9792篇 |
2012年 | 13847篇 |
2011年 | 14240篇 |
2010年 | 13507篇 |
2009年 | 12064篇 |
2008年 | 11628篇 |
2007年 | 10797篇 |
2006年 | 8954篇 |
2005年 | 7726篇 |
2004年 | 4883篇 |
2003年 | 3128篇 |
2002年 | 3031篇 |
2001年 | 2849篇 |
2000年 | 2431篇 |
1999年 | 1087篇 |
1998年 | 168篇 |
1997年 | 140篇 |
1996年 | 113篇 |
1995年 | 135篇 |
1994年 | 130篇 |
1993年 | 106篇 |
1992年 | 223篇 |
1991年 | 206篇 |
1990年 | 222篇 |
1989年 | 192篇 |
1988年 | 201篇 |
1987年 | 145篇 |
1986年 | 172篇 |
1985年 | 123篇 |
1979年 | 134篇 |
1975年 | 137篇 |
1974年 | 129篇 |
1973年 | 116篇 |
1972年 | 138篇 |
1971年 | 118篇 |
1969年 | 102篇 |
1968年 | 113篇 |
1967年 | 125篇 |
1966年 | 106篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
72.
中药对肉仔鸡脂质代谢及肉品质的影响 总被引:16,自引:3,他引:13
将120只1周龄肉仔鸡随机分成4组,每组30只,前3组(试验Ⅰ、Ⅱ、Ⅲ组)分别喂以含1%的3种不同中药组方的饲粮,第Ⅳ组为对照组,只喂基础日粮.试验期6周.结果(1)与对照组相比,Ⅰ组血清TC、LDL-C极显著下降(P<0.01);Ⅱ组血清TC、LDL-C极显著下降(P<0.01),TG也下降(P<0.05),HDL-C显著升高(P<0.01);Ⅲ组血清LDL-C极显著下降(P<0.01),HDL-C则显著升高(P<0.01);试验Ⅰ~Ⅲ组血清总脂都极显著下降(P<0.01);与Ⅱ组相比,Ⅰ组血清LDL-C、Ⅲ组TC存在显著差异(P<0.01).(2)与对照组相比,胸肌组织中,各试验组TG极显著下降(P<0.01),Ⅱ组TC显著下降(P<0.05);腿肌中,各组TC显著下降(P<0.05),TG下降极显著(P<0.01);肝脏中各组TC、TG均极显著下降(P<0.01);与Ⅱ组相比,Ⅰ组肝TG差异极显著(P<0.01);Ⅲ组胸肌TG、肝TG有显著差异性(P<0.05).(3)7周龄末鸡体重与对照组相比,Ⅱ组差异极显著(P<0.01),Ⅲ组差异显著(P<0.05);Ⅱ组料肉比比对照组极显著下降(P<0.01).(4)肌肉中的营养成分,Ⅰ、Ⅱ组腿肌中粗脂肪比对照组极显著下降(P<0.01),Ⅱ组腿肌中粗蛋白含量显著升高(P<0.01).结论中药组方能不同程度地调整鸡脂质代谢,提高生产性能和改善鸡肉品质.在3个不同中药组方中,综合效果Ⅱ方最优. 相似文献
73.
In a feeding trial lasting for months Halothane-positive fattening pigs were put on a diet containing different concentrations of vitamin E and selenium. After a Myostress application vitamin E and selenium were additionally injected in order to examine stress resistance (CK-test) and regenerative capacity (histological examination of Musculus longissimus dorsi) of skeletal muscle. The study revealed that neither high dietary levels of vitamin E/selenium nor a vitamin E/selenium treatment applied after stress are capable of preventing stress related myopathy nor can they influence its healing up favourably. 相似文献
74.
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
75.
R K?stlin 《Tier?rztliche Praxis》1988,16(4):351, 436-351, 437
76.
Eradication of lice in cattle. 总被引:8,自引:0,他引:8
The purpose of this field study was to develop and evaluate eradication as a strategy to control lice in cattle. Thirty-three herds of cattle were selected and observed during a period of two and a half years. Before eradication, biting lice (Damalinia bovis) were present in 94% of the herds and 27% of the animals. Sucking lice (Linognathus vituli) were present in 42% of the herds and 5% of the animals. These levels were very similar to those reported from other countries in Northern Europe. The eradication strategy was successful in 28 of 33 herds, but lice were still present in 5 herds 3 to 6 months after treatment. Biting lice were present in all these 5 herds, sucking lice were present in 3 herds. During the next 12 months, nine of the 28 herds were reinfected with lice. Six herds were reinfected with just biting lice, 2 herds with just sucking lice and one herd was reinfected with both. There was no significant difference between the 2 louse species regarding the risk of unsuccessful eradication or reinfection. The only significant risk factor for reinfection was either purchase of livestock or use of common pasture, combined with failure in pre-treatment of newly introduced animals. 相似文献
77.
78.
79.
80.