全文获取类型
收费全文 | 5682篇 |
免费 | 330篇 |
国内免费 | 1篇 |
专业分类
林业 | 1039篇 |
农学 | 164篇 |
基础科学 | 10篇 |
1209篇 | |
综合类 | 538篇 |
农作物 | 145篇 |
水产渔业 | 189篇 |
畜牧兽医 | 2193篇 |
园艺 | 120篇 |
植物保护 | 406篇 |
出版年
2023年 | 35篇 |
2022年 | 37篇 |
2021年 | 82篇 |
2020年 | 78篇 |
2019年 | 42篇 |
2018年 | 187篇 |
2017年 | 176篇 |
2016年 | 158篇 |
2015年 | 137篇 |
2014年 | 150篇 |
2013年 | 368篇 |
2012年 | 321篇 |
2011年 | 347篇 |
2010年 | 163篇 |
2009年 | 145篇 |
2008年 | 283篇 |
2007年 | 311篇 |
2006年 | 303篇 |
2005年 | 260篇 |
2004年 | 254篇 |
2003年 | 274篇 |
2002年 | 216篇 |
2001年 | 179篇 |
2000年 | 173篇 |
1999年 | 106篇 |
1998年 | 35篇 |
1997年 | 37篇 |
1996年 | 44篇 |
1995年 | 73篇 |
1994年 | 43篇 |
1993年 | 21篇 |
1992年 | 26篇 |
1991年 | 23篇 |
1990年 | 30篇 |
1989年 | 25篇 |
1988年 | 28篇 |
1987年 | 16篇 |
1986年 | 33篇 |
1985年 | 33篇 |
1984年 | 24篇 |
1983年 | 22篇 |
1980年 | 27篇 |
1979年 | 15篇 |
1978年 | 16篇 |
1977年 | 25篇 |
1975年 | 14篇 |
1973年 | 18篇 |
1966年 | 16篇 |
1955年 | 14篇 |
1941年 | 14篇 |
排序方式: 共有6013条查询结果,搜索用时 0 毫秒
21.
Ohne Zusammenfassung 相似文献
22.
23.
24.
25.
Ohne Zusammenfassung 相似文献
26.
Groszh. bad. Oberförster Gretsch 《European Journal of Forest Research》1898,20(9):455-477
27.
Chicory (Cichorium intybus) belongs to plants of the Compositae family accumulating energy in the form of inulin fructan. Chicory, a prebiotic, is a fermentable oligosaccharide and oligofructose that may affect the intestinal mucosal architecture and the electrophysiological parameters. Therefore, this study was conducted to evaluate the effectiveness of adding chicory fructans in feed on the intestinal morphology and electrogenic transport of glucose in broilers. Four hundred, 1 day old broiler chicks were randomly divided into two groups (200 bird per group) for 5 weeks. The dietary treatments were (i) control, (ii) basal diets supplemented with the dried, grinded ground chicory pulp containing inulin (1 kg of chicory/ton of the starter and grower diets). In duodenum, dietary chicory increased the villus height and villus width and villus height to crypt depth ratio (p < 0.05), but the duodenal crypt depth remained unaffected (p > 0.05). However, in jejunum, the villus height, crypt depth and villus height to crypt depth ratio were decreased by dietary chicory compared with control birds (p < 0.05). In ileum, the villus height and villus crypt depth was decreased by dietary chicory supplementation compared with control (p < 0.05), but, the villus height to crypt depth ratio was increased (p < 0.05). Moreover, dietary chicory relatively affected the electrophysiological parameters of the intestine but did not reach significance. The amount of ΔIsc after d ‐glucose addition to the jejunal mucosa was numerically higher for chicory fed birds (19 μA/cm2) than control birds (10 μA/cm2). The percentage of increase in the Isc after d ‐glucose addition (ΔIsc %) was higher for chicory group upto (90%) of the control group. In colon, the actual Isc value and Isc after d ‐glucose addition was numerically higher for chicory fed birds than control birds (p > 0.05). Moreover, the conductance of jejunal and colonic tissues after d ‐glucose addition remained unaffected by the dietary chicory. In conclusion, addition of chicory to broilers diet increased the duodenal villus height, villus width and villus height to crypt depth ratio and decreased the villus height and crypt depth in both jejenum and ileum. Furthermore, dietary chicory relatively modified the small intestinal electrogenic transport of glucose in broilers. 相似文献
28.
Ramona Weishaar Robin Wellmann Amelia Camarinha-Silva Markus Rodehutscord Jörn Bennewitz 《Zeitschrift für Tierzüchtung und Züchtungsbiologie》2020,137(1):14-22
Most traits in animal breeding, including feed efficiency traits in pigs, are affected by many genes with small effect and have a moderately high heritability between 0.1 and 0.5, which enables efficient selection. Since the microbiota composition in the gastrointestinal tract is also partly heritable and was shown to have a substantial effect on feed efficiency, the host genes affect the phenotype not only directly by altering metabolic pathways, but also indirectly by changing the microbiota composition. The effect of the microbiota composition on the breeding value of an animal is the conditional expectation of its breeding value, given the vector with microbiota frequencies, that is The breeding value of an animal can therefore be decomposed into a heritable contribution that arises from an altered microbiota composition and a heritable contribution that arises from altered metabolic pathways within the animal, so Instead of selecting for breeding value , an index comprising the two components and with appropriate weights, that is , can be used. The present study shows how this breeding strategy can be applied in pig genomic selection breeding scheme for two feed efficiency traits and daily gain. 相似文献
29.
S. Zetterström R. Hanson A. Velloso Alvarez F. Caldwell L. Boone J. Schumacher 《Equine Veterinary Education》2021,33(12):e482-e489
Conidiobolus coronatus is one of the most commonly identified upper respiratory fungal pathogens in horses. This article includes a review of clinical signs, diagnostics, treatment and outcomes in previously reported cases of equine conidiobolomycosis, as well as six additional cases seen at our hospital. Each of the six horses presented with a complaint of serosanguinous or haemorrhagic nasal discharge and conidiobolomycosis was confirmed by histopathology and fungal culture. Five horses recovered after administration of antifungal drugs alone (n = 4) or in combination with extensive nasal septum resection (n = 1). Surgical treatment alone was ineffective. One horse was euthanised without treatment because of the extent of the disease. 相似文献
30.
Köster LS Schoeman JP Meltzer DG 《Journal of the South African Veterinary Association》2007,78(3):133-136
Serum cortisol response was assessed in 8 captive cheetahs, of varying ages, after the intravenous administration of 500 microg of tetracosactide (Synacthen Depot, Novartis, Kempton Park) while maintained under general anaesthesia. In addition, 8 cheetahs were anaesthetised and given an equal volume of saline in order to establish baseline cortisol concentrations at similar stages of anaesthesia. A significant difference in the median cortisol concentration measured over time was found following ACTH administration in the ACTH group (P < 0.001). There was no difference between the median cortisol concentrations in the ACTH group at time-points 120, 150 and 180 min after ACTH stimulation (P = 0.867). Thus it appears appropriate to collect serum 120 to 180 min after tetracosactide administration to assess maximal stimulation of the adrenal in the cheetah. No statistically significant rise was seen in the anaesthetised control group following the injection of saline (P = 0.238). 相似文献