全文获取类型
收费全文 | 435篇 |
免费 | 30篇 |
国内免费 | 27篇 |
专业分类
林业 | 10篇 |
农学 | 38篇 |
基础科学 | 1篇 |
19篇 | |
综合类 | 201篇 |
农作物 | 25篇 |
水产渔业 | 73篇 |
畜牧兽医 | 98篇 |
园艺 | 7篇 |
植物保护 | 20篇 |
出版年
2023年 | 5篇 |
2022年 | 4篇 |
2021年 | 8篇 |
2020年 | 12篇 |
2019年 | 14篇 |
2018年 | 10篇 |
2017年 | 14篇 |
2016年 | 17篇 |
2015年 | 13篇 |
2014年 | 21篇 |
2013年 | 20篇 |
2012年 | 44篇 |
2011年 | 24篇 |
2010年 | 27篇 |
2009年 | 30篇 |
2008年 | 27篇 |
2007年 | 34篇 |
2006年 | 29篇 |
2005年 | 18篇 |
2004年 | 8篇 |
2003年 | 7篇 |
2002年 | 19篇 |
2001年 | 3篇 |
2000年 | 14篇 |
1999年 | 14篇 |
1998年 | 6篇 |
1997年 | 6篇 |
1996年 | 3篇 |
1995年 | 8篇 |
1994年 | 6篇 |
1993年 | 2篇 |
1992年 | 7篇 |
1991年 | 6篇 |
1990年 | 4篇 |
1989年 | 3篇 |
1988年 | 2篇 |
1983年 | 1篇 |
1979年 | 1篇 |
1978年 | 1篇 |
排序方式: 共有492条查询结果,搜索用时 15 毫秒
11.
The activity and capacity (activity × tissue weight) of digestive carbohydrases (total carbohydrase, α‐glucosidase, α‐amylase) was examined in vitro under a range of (more realistic) incubation temperatures (5, 18 and 25°C) and pH (7.6) more likely to be encountered during rearing, along the digestive tract of important teleost species for aquaculture (Dicentrarchus labrax, Sparus aurata, Oreochromis aureus, Oncorhynchus mykiss and Salmo salar). Results indicate, among other things, an overestimation of digestive carbohydrase levels when performing assays at 37°C, a different effect of temperature on digestive enzyme performance along the digestive tract of examined species, and the increased importance of α‐glucosidase towards carbohydrate digestion. Implications regarding the capacity of each species for carbohydrate digestion in nature, as well as feed manufacturing, are discussed. 相似文献
12.
C.?A.?Alvarez-González M.?Cervantes-Trujano D.?Tovar-RamírezEmail author D.?E.?Conklin H.?Nolasco E.?Gisbert R.?Piedrahita 《Fish physiology and biochemistry》2005,31(1):83-93
California halibut Paralichthys californicus is an important commercial species with high aquaculture potential in Baja California Sur, México. To optimize the feeding
process using live prey and/or inert diets, we evaluated alkaline proteases, pepsin, trypsin, chymotrypsin, leucine aminopeptidase,
lipase, α-amylase, and acid and alkaline phosphatase activities on starved larvae and larvae fed live prey. Highest activities
were observed for alkaline protease, trypsin, chymotrypsin, leucine aminopeptidase, and alkaline phosphatase in feeding larvae
than starved larvae on day 4 after hatching. At day 5, a sizeable increase in all enzymatic activities was detected in feeding
larvae. Alkaline protease, trypsin, chymotrypsin, and alkaline phosphatase decreases progressively from day 5 until day 18.
At day 18, a slight pepsin activity was observed. This was considered an indicator of the start of digestive system maturation.
We concluded that total enzymatic equipment for this species is complete between day 18 and 30 after hatching. Based on this
evidence, early weaning from live prey to inert feed would be possible at this time. 相似文献
13.
14.
Rinat Ismagilovich Ibragimov ;Ildar Salimyanovich Mardanshin ;Galina Vasilyevna Benkovskaya ;Maksim Borisovich Udalov ;Irina Andreevna Shpirnaya ;Vyacheslav Olegovich Tsvetkov 《农业科学与技术》2014,(4):331-341
In field and laboratory conditions the reproductive potential (survival at different stages of development) of the Colorado potato beetle has been measured, the dependence of the parameters of insects fertility on varietal features of the feed has been investigated, the food activity of the representatives of insects from four areas of the Southern Urals has been measured, the intensity and time of hypersensitivity reactions on potato leaves has been defined. In laboratory experiments, the level of activity of hydrolytic enzymes in insects and the level of activity of these enzymes inhibitors in the leaves of three potato varieties differing in their resistance to the Colorado potato beetle have been determined. The results show that the insects-representatives of different samples have different food activity in relation to different potato varieties. High mortality rates were revealed at feeding with leaves of potato of the Bashkir variety characterized by a high level of hydrolases inhibitors and relatively rapid development of necrotic reactions after the appearance of eggs laying on the leaves. We suppose that the neerogenetic barrier appearing in the form of necrosis is the major cause of the fetal mortality of insects. The level of the content of inhibitors inactivating larvae digestive enzymes affects the survival of insects at postembryonic stages. The speed of the necrosis emergence, the level of activity of digestive enzymes inhibitors in potato can be considered as criteria for the selection of breeding material for resistance to the Colorado potato beetle. 相似文献
15.
[目的]筛选并分析天山一号冰川冰层产淀粉酶的低温酵母菌。[方法]对天山一号冰川冰层含冰冻土产低温淀粉酶的低温酵母菌菌株进行筛选、纯化,并对其生理多样性和系统发育多样性进行研究。[结果]从天山一号冰川冰层含冰冻土中分离出60株酵母菌,并从中筛选出6株产低温淀粉酶的菌株,根据细胞菌落形态、菌体特征和26S rDNA D1/D2区域序列系统发育分析,6株菌分别隶属于红酵母属(Rhodotorula)、隐球菌属(Cryptococcus)和掷孢酵母属(Sporobolomyces),最适生长温度为20~24℃,为兼性耐冷细菌。[结论]研究可为了解冰川酵母菌的系统发育多样性以及低温淀粉酶的生物技术研发奠定基础。 相似文献
16.
多效唑对高羊茅叶片糖酶活性的影响 总被引:20,自引:4,他引:16
高羊茅草坪草施用多效唑后,叶片的垂直生长受抑,叶片光合同化物向根系运输增强,叶片和根系中淀粉及可溶性糖含量升高。数据表明:叶片中淀粉含量与淀粉酶活性呈正相关(r=0.88)。,另外,叶片中酸性转化酶活性增加,但中性转化酶活性降低,且叶片中可溶性碳水化合物含量一直维持在较高水平,说明酸性转化酶在多效唑对草坪草叶片垂直生长的调节中起重要作用。草坪草生长动态的变化与多效唑改变碳水化合物代谢酶活性有关。可溶性糖的积累有利于增强草坪草抗逆性,促进新器官的发生。 相似文献
17.
Serum amylase and isoamylase values were determined in three groups of dogs. The first group contained control dogs while the other groups contained dogs with confirmed exocrine pancreatic insufficiency and diabetes mellitus respectively. The trypsin-like immunoreactivity test was also carried out on sera from dogs with exocrine pancreatic disease (EPI). A significant difference was detected in the serum amylase values between the three groups which may be of limited diagnostic value. Dogs with EPI had values lower than normal while those with diabetes mellitus had values higher than control dogs. No evidence of exocrine pancreatic insufficiency was found in dogs with diabetes mellitus. 相似文献
18.
Eva Johansson 《Euphytica》2002,126(1):143-149
Variation in falling number, amylase activities, protein concentration and composition were investigated in two wheat cultivars
grown in Sweden over two seasons, in four locations, with four N fertilizer rates, with and without fungicide treatment. The
results showed that;
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
• | Tarso had higher falling number, amylase activities, protein concentration and amount of most protein components compared to Kosack. |
• | The environment (year, location, N rate and fungicide treatment) influenced falling number, alpha amylase activities, and protein concentration and composition. |
• | Two processes were related to low falling numbers; late maturity leading to poor starch and protein quality and excessive rains leading to break-down of starch and proteins. |
• | Poor starch and protein properties influenced the bread-making quality to a higher extent than break-down of starch and proteins. |
19.
20.