全文获取类型
收费全文 | 979篇 |
免费 | 163篇 |
国内免费 | 77篇 |
专业分类
林业 | 3篇 |
农学 | 23篇 |
基础科学 | 15篇 |
45篇 | |
综合类 | 193篇 |
农作物 | 17篇 |
水产渔业 | 875篇 |
畜牧兽医 | 45篇 |
园艺 | 1篇 |
植物保护 | 2篇 |
出版年
2024年 | 2篇 |
2023年 | 13篇 |
2022年 | 16篇 |
2021年 | 28篇 |
2020年 | 52篇 |
2019年 | 58篇 |
2018年 | 52篇 |
2017年 | 60篇 |
2016年 | 60篇 |
2015年 | 35篇 |
2014年 | 45篇 |
2013年 | 137篇 |
2012年 | 44篇 |
2011年 | 67篇 |
2010年 | 54篇 |
2009年 | 35篇 |
2008年 | 59篇 |
2007年 | 43篇 |
2006年 | 51篇 |
2005年 | 47篇 |
2004年 | 42篇 |
2003年 | 36篇 |
2002年 | 38篇 |
2001年 | 37篇 |
2000年 | 17篇 |
1999年 | 22篇 |
1998年 | 11篇 |
1997年 | 13篇 |
1996年 | 11篇 |
1995年 | 14篇 |
1994年 | 6篇 |
1993年 | 8篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1986年 | 1篇 |
排序方式: 共有1219条查询结果,搜索用时 31 毫秒
101.
Pigment deficiency correction in shrimp broodstock using Spirulina as a carotenoid source 总被引:1,自引:0,他引:1
In this study, an effort was made to cure the pigment deficiency syndrome (PDS) exhibited by pond‐reared Fenneropenaeus indicus (H.Milne Edwards) broodstock, using the blue‐green algae Spirulina as a carotenoid source in diet. The PDS symptoms included bleaching of ovary and reduced early larval performance. Biochemical analysis indicated reduced quantity of total carotenoids in egg and nauplii from the females with PDS. When PDS females were fed 30 g kg?1Spirulina‐supplemented diet immediately after the appearance of symptoms, the egg and nauplii carotenoid values improved gradually and attained the pre‐PDS values after a minimum of 4 week period. Spirulina supplementation also improved significantly (P < 0.05) the spawn quality (hatch per spawn, nauplii per spawn, nauplii viability) and larval quality indices (P < 0.05). The egg and nauplii protein values exhibited a trend similar to carotenoids, confirming the influence of latter on protein stability previously reported by researchers. The study confirms the bioavailability of carotenoids from Spirulina to shrimp broodstock and recommends its regular inclusion in diet to preclude carotenoid deficiency‐related problems in shrimp hatcheries. 相似文献
102.
103.
The septate gregarine Nematopsis marinus n. sp. (Apicomplexa: Cephaline) heavily infected the midgut of cultured Pacific white shrimp Litopenaeus vannamei (Boone) in Ecuador. It is morphologically similar to other species of the genera Nematopsis, but it can be distinguished from them, by having gamonts with a prominent hemispherical protomerite that contained numerous refractile granules and unusual strong gliding movement. There is evidence that shrimp acquired the infection in the ponds, as larval or postlarval stages do not showed infection. Juveniles and adult shrimp had a prevalence and intensity of infection ranging from 50% to 80% and 10 to > 5000 parasites respectively. When voided from the gut, the gregarine keep alive in seawater. This gregarine have been associated with the marine environment and there are no records of this species in low salinity waters or freshwater. Results suggest that N. marinus could have most of the life cycle of the species within the host L. vannamei. 相似文献
104.
Effect of culture system on the nutrition and growth performance of Pacific white shrimp Litopenaeus vannamei (Boone) fed different diets 总被引:2,自引:0,他引:2
A.G.J. TACON J.J. CODY L.D. CONQUEST S. DIVAKARAN I.P. FORSTER & O.E. DECAMP 《Aquaculture Nutrition》2002,8(2):121-137
Two 8-week feeding trials were conducted with juvenile Pacific white shrimp, Litopenaeus vannamei (Boone) to compare the growth and performance of animals fed a series of experimental and commercial pelleted shrimp and fish feeds and dietary feeding regimes within an indoor running-water culture system and an outdoor zero-water-exchange culture system. The best overall shrimp growth performance was observed for animals fed the experimental shrimp diet and all-day feeding regime under outdoor zero-water-exchange culture conditions. Final body weight and average weekly growth rate under these conditions were 2.8 and 3.4 times greater, respectively, than animals of similar size fed with the same diet under indoor running-water culture conditions. Although direct comparison between indoor and outdoor culture systems is difficult because of the lower indoor water temperatures, and consequently lower mean daily feed intake of animals, it is believed that the higher growth and feed performance of animals reared under outdoor `green-water' culture conditions was primarily due to their ability to obtain additional nutrients from food organisms endogenously produced within the zero-water-exchange culture system. The most promising features of zero-water-exchange culture systems are that they offer increased biosecurity, reduced feed costs and water use for the farmer, and by doing so provide a potential avenue of moving the shrimp culture industry along a path of greater sustainability and environmental compatibility. 相似文献
105.
试验旨在建立灵敏、快速、特异的氯霉素(CAP)检测方法,基于免疫亲和色谱技术和酶联免疫技术,研究了一种新型快速检测虾肉中CAP的免疫亲和色谱柱(ICTC)检测方法。采用溶胶-凝胶(sol-gel)法制备ICTC柱的检测层和控制层,优化检测层、控制层、酶标物(CAP-HRP)稀释度等条件,制备ICTC柱。测定ICTC柱的灵敏度、特异性等性能参数,并对虾肉样本前处理方法和基质干扰效应进行优化。本研究确定ICTC柱条件为:检测层,anti-CAP sol-gel:空白sol-gel为10:1 000(V/V);控制层,anti-HRP sol-gel:空白sol-gel为13:1 000(V/V);CAP-HRP的稀释度为1:105。采用检测层消色法判定结果,检测时间10 min,PBS缓冲液中CAP的检测限为0.5 μg/L,该方法与甲砜霉素、氟苯尼考、氟苯尼考胺同类药物或代谢产物均无可见交叉反应,在虾肉样本中的检测限为0.75 μg/kg。本研究建立的ICTC柱检测方法快速、灵敏,使用方便,为现场快速检测虾肉中CAP残留提供了新的技术手段。 相似文献
106.
《The Journal of Applied Poultry Research》2018,27(1):45-50
An experiment was carried out to measure the suitability of using formic acid-treated shrimp meal (TSM) as a protein source for aged laying hens. Shrimp meal (SM), air-dried shrimp waste was treated with 3% formic acid (w/v) at room temperature for 20 min, sun-dried, ground to pass through 1.0 mm mesh screen and then ready to use as the TSM. A total of 56 Single Comb White Leghorn hens, 85 wk of age, were placed in individual cages and assigned randomly into 7 dietary groups of 8 birds each. A control diet, diets containing 5, 10, and 15% SM and diets containing 5, 10, and 15% TSM were prepared. Diets and water were given ad libitum during the 30-d experimental period. Hen-day egg production, egg mass, feed intake, and feed conversion ratio (FCR) were deteriorated with increasing levels of the SM in the diets (P < 0.05). In contrast, these parameters were unchanged with increasing levels of the TSM in diets and compatible with the control group. No significant improvements were observed in exterior or interior egg quality among the dietary groups, except for eggshell weight, strength and yolk color, which were significantly increased in SM and TSM groups when compared to the values in control group (P < 0.05). It is concluded that inclusion of TSM up to 15% in laying hen diets may have beneficial effects on laying performance along with improved eggshell quality and yolk color, and suggested that TSM is a promising combined source of protein and calcium in aged laying hens. 相似文献
107.
108.
研究和探讨了虾加工副产物的酶解产物(Enzymatic Hydrolysis Production,EHP)对蛋鸡产蛋率和蛋品质的影响。以虾加工副产物为原料,应用复合生物酶酶解技术制备EHP,选择产蛋率在80%以上的300日龄笼养褐壳蛋鸡288只,随机分成3组,在基础日粮中分别添加0、1.5g/100g、3g/100g虾加工副产物EHP,并替代相应重量的鱼粉,试验期为60天。EHP,可显著提高鸡蛋的哈夫单位(P〈0.05),试验组蛋鸡产蛋率平均提高3.14%,料蛋比相应低于对照组。表明虾加工副产物EHP可显著提高产蛋高峰期过后处于衰减期的鸡蛋的哈夫单位及产蛋率。 相似文献
109.
110.
ABSTRACT: The reproductive traits and the monthly larval abundance of the mantis shrimp Oratosquilla oratoria were investigated in Tokyo Bay, Japan, in 2002. The goal of the study was to elucidate the cause of changes in the monthly pattern of larval abundance from the 1980s to the 1990s as these changes relate to variation in the stock size of the adult shrimp. Oogenesis was divided into 10 stages by histological observation. The developmental stage of oocytes in an individual's ovary was synchronous, suggesting that almost all the oocytes in an ovary are spawned at the same time. The size at first maturity was estimated to be 7 ≤ body length ( BL ) < 8 cm. Fecundity was expressed as a function of BL , ranging from 19 300 eggs for 8 cm BL to 92 100 eggs for 14 cm BL . Small female shrimps (<10 cm BL ) spawned around August. Most large female shrimps (≥10 cm BL ) spawned around May, and some large female shrimps also spawned until September. Although most large female shrimps spawned in spring, the larval abundance was low before July and high from August onwards. The results suggest that a substantial decrease in the stock size of large individuals causes the low larval abundance before July. 相似文献