首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   1361篇
  免费   42篇
  国内免费   54篇
林业   60篇
农学   149篇
基础科学   75篇
  147篇
综合类   570篇
农作物   81篇
水产渔业   19篇
畜牧兽医   43篇
园艺   225篇
植物保护   88篇
  2024年   6篇
  2023年   17篇
  2022年   44篇
  2021年   36篇
  2020年   34篇
  2019年   42篇
  2018年   27篇
  2017年   47篇
  2016年   45篇
  2015年   43篇
  2014年   91篇
  2013年   89篇
  2012年   108篇
  2011年   104篇
  2010年   105篇
  2009年   81篇
  2008年   65篇
  2007年   68篇
  2006年   58篇
  2005年   36篇
  2004年   39篇
  2003年   41篇
  2002年   35篇
  2001年   22篇
  2000年   19篇
  1999年   22篇
  1998年   15篇
  1997年   10篇
  1996年   20篇
  1995年   15篇
  1994年   9篇
  1993年   12篇
  1992年   6篇
  1991年   17篇
  1990年   9篇
  1989年   9篇
  1988年   4篇
  1984年   1篇
  1983年   2篇
  1980年   1篇
  1979年   1篇
  1978年   1篇
  1977年   1篇
排序方式: 共有1457条查询结果,搜索用时 15 毫秒
141.
ABSTRACT

1. Olive leaf extract (OLE) and hazelnut skin (HS), which are known to have good antioxidant activity, were added into chicken nuggets in different ways. In the first method, the nuggets were coated with sodium alginate-calcium chloride-based coatings containing OLE and HS. In the second method, OLE and HS were directly added into the nugget patties. Nuggets that did not contain any additive (C1) and the samples prepared with the coating solution that did not include any additives (C2) were assigned as controls.

2. Nuggets were stored at two different temperatures, either in a refrigerator (4°C) or in a deep freezer (?18°C) for 21 days and 90 days respectively. Moisture content (%), pH, antioxidant status (TBARS), colour and microbial count (total mesophilic and psychrophilic aerobic bacteria) analyses were carried out during storage.

3. At the end of refrigerator storage (day 21), TBARS values for samples in which OLE and HS were directly added were found to be lower than those with OLE and HS coatings (P < 0.05). Total number of mesophilic and psychrophilic bacteria were found to be the lowest in the treatment in which HS was directly incorporated into nugget patty (P < 0.05).

4. For frozen samples, application of a coating containing OLE and HS and direct addition of HS into patties were found to be effective in reducing lipid oxidation. No microbial growth was determined in most of the samples stored in the deep freezer.  相似文献   
142.
我国食用菌眼蕈蚊的研究现状   总被引:5,自引:3,他引:2  
简要综述了我国食用菌害虫眼蕈蚊的研究概况,统计了危害食用菌的眼蕈蚊科5属20余种,概述了眼蕈蚊的危害特点、生物学特性及防治方法等。并探讨了研究中存在的问题和今后的发展方向。  相似文献   
143.
食用菌异迟眼蕈蚊Bradysia difformis的生物学特性   总被引:1,自引:0,他引:1  
异迟眼蕈蚊是云南省食用菌主要栽培区双翅目害虫的优势种之一,为国内新记录种。记述了异迟眼蕈蚊的外部形态鉴别特征,并简要描述了各虫态的生物学特性。2007年9月至2008年2月,异迟眼蕈蚊成虫的发生有3个明显的高峰期,分别在2007年9月下旬、11月上旬和12月中旬,从2007年12月中旬至2008年2月下旬,成虫发生数量呈下降趋势。  相似文献   
144.
We have performed a field experiment to investigate the survival and vitality of perennial plants in a living wall installed in an industrial area in Malmö, southern Sweden. The main aim of the study was to investigate the possibility of growing edible and evergreen perennial plants in living wall systems in the Scandinavian climate. We conclude that the edible perennial plants Allium schoenoprasum, Calamintha nepeta, and Fragaria vesca are feasible in living wall systems in the Scandinavian climate. Thymus vulgaris is sensitive to the Scandinavian climate, and performed equally poorly in Rockwool panels and in soil-filled containers (controls). We also conclude that the evergreen perennial plant species Chamaecyparis pisifera, Euonymus fortuneii, Euphorbia polychroma, Vinca minor, and Waldsteinia ternata can be grown in green walls, and that the edible evergreen plant Vaccinium vitis-idea is highly suitable for living walls in this climatic region. A. schoenoprasum, C. pisifera, E. fortuneii, I. crenata, L. sylvatica, V. minor, and V. vitis-idea showed 100% survival rates, however, the visual quality of e.g. I. crenata and L. sylvatica was not acceptable for ornamental purposes.  相似文献   
145.
Interspecific crosses were made between the cultivated sunflower inbred line HA89 and accessions of five wild perennial Helianthus species (H. giganteus L., H. laevigatus T. & G., H. resinosus Small, H. pauciflorus Nutt. and H. decapetalus L.) resistant to broomrape ( Orobanche cernua Loefl.). Using the genetic male-sterile isogenic version of that line as female, successful reciprocal crosses were also obtained with all these wild species except with H. decapetalus. Five-day-old hybrid embryos were excised and cultured in vitro. In all cases, few mature plants were obtained from embryos in early developmental stages (early heart and globular) but up to 28% mature plants were obtained from embryos in later stages of development. Very immature embryos were difficult to excise without damage. Hybrid embryos and mature plants were obtained from all five wild species. Interspecific hybrid embryos from different wild species showed distinct developmental potentials, the proportion of hybrid embryos in different developmental stages varying among species. Differences in the proportion of hybrid embryos at the several developmental stages were also obtained for the reciprocal crosses (cultivated × wild), which showed higher proportion of fully developed embryos. Hybrids involving H. giganteus and cultivated sunflower were difficult to obtain without the use of embryo culture. Embryo culture proved to be an useful tool to overcome post-zygotic hybrid incompatibility in different Helianthus spp., and facilitated interspecific transfer of resistance to O. cernua. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   
146.
为明确不同类型向日葵籽粒理化性质与利用价值,以3种不同类型向日葵籽仁为研究对象,检测其粗蛋白质、粗脂肪、氨基酸、微量元素、维生素E和植物甾醇含量,脂肪酸组成以及抗氧化活性.研究表明,观赏向日葵阿尔卑斯橙子红晕黑心和食用向日葵JZ055粗脂肪含量分别为44.55%和41.26%,低于油用向日葵陇葵杂6号(49.93%),...  相似文献   
147.
巴楚蘑菇研究Ⅰ.营养成分   总被引:7,自引:1,他引:6  
研究了生产于新疆南部巴楚县的珍稀名贵野生食用菌巴楚蘑菇的蛋白质,氨基酸,脂肪与脂肪酸及矿质元素含量与组成。结果表明(1)巴楚蘑菇中的蛋白质含量高于平菇,香菇及黑木耳,略低于新疆所产美味食和菌粗槽羊肝菌;氨基酸总量、人体必需氨基酸含量及其占氨基酸总量的比率均与百肝菌相似;  相似文献   
148.
由大丽轮枝孢菌侵染引起的向日葵黄萎病是一种重要的土传病害,微菌核是该病害主要的初侵染来源。目前,土壤中大丽轮枝孢菌微菌核的定量检测方法多操作步骤复杂繁琐,如利用PCR方法进行检测,对仪器设备和操作人员的素质都有较高的要求,而常规的土壤梯度稀释湿筛法的实验周期长且检测效率低,因此,建立一种快速定量检测土壤中大丽轮枝孢菌微菌核的方法,对于向日葵黄萎病的预报预测和防控非常重要。为了能够快速的定量检测土壤中微菌核的数量,以期探明不同耕作方式地块中土壤微菌核数量的差异,本实验建立了一套操作相对简单,实验周期较短的微菌核快速分离和定量检测的方法,即采样器—干筛法。该方法将微生物采样器和选择性培养基相结合,基于微生物采样器的撞击法原理,使土壤微生物粒子加速撞击到选择性培养基的培养皿表面,经培养后可见单菌落形成。利用该方法对内蒙古巴彦淖尔市不同的向日葵黄萎病发病地块中采集到的土壤样本中微菌核进行了定量检测,结果表明:两年向日葵连作地(样地1)土壤中微菌核的数量最多,平均每克土样中含有微菌核32.80个;与非寄主作物玉米轮作地块(样地2)土样中微菌核的数量最少,平均每克土样中含有微菌核11.80个,与寄主作物打籽葫芦轮作地块(样地3)微菌核数量介于二者之间。利用该方法能够明显区分不同地块土壤中微菌核的数量。通过和荧光定量PCR检测的结果进行相关性分析发现,该方法能够准确检测土壤中大丽轮枝孢菌微菌核的数量。  相似文献   
149.
A feeding trial with Macrobrachium rosenbergii was carried out to test the effectiveness of sunflower cake (SFC) as a replacement for conventional protein sources. Four isonitrogenous (~30% crude protein) and isocaloric (388–402 kcal) diets were formulated. Diet‐1 was a control made with conventional ingredients including fish meal, soya bean meal and mustard oil cake. Diet‐2, Diet‐3 and Diet‐4 were made with 30%, 40% and 50% SFC, respectively, replacing the usual protein sources used in Diet‐1. After 100 days, diets with SFC inclusion showed favourable growth and economic performance trends compared to control diet‐1, but without significant differences (p > .05). Better production (572.89 ± 62.99 kg/ha) was observed with Diet‐4 followed by Diet‐2, Diet‐3 and Diet‐1. Diet‐4 revealed the best feed conversion ratio (2.56 ± 0.24), specific growth rate (1.18 ± 0.05) and protein efficiency ratio (1.14 ± 0.10) among these diets. Whole carcass composition analysis revealed highest crude protein (18.19%) and lipid (4.43%) content in prawns fed Diet‐3 followed by Diet‐4. Highest total income, gross margin and benefit cost ratio (BCR) per hectare from prawns were US$5,759, US$2,623 and 1.84, respectively, found in Diet‐4. This study demonstrates that 30%–50% inclusion of SFC has favourable impacts on productivity and profitability compared with controls, with 50% SFC inclusion as the most cost‐effective diet for prawns without apparent compromise in growth, flesh quality or economics. The performances of the diets suggest that SFC may be a suitable substitute for fishmeal, soya bean meal and mustard oil cake in prawn feed. The effectiveness of higher SFC concentrations should also be investigated.  相似文献   
150.
盐渍化土壤向日葵水-肥耦合试验研究   总被引:1,自引:0,他引:1  
以内蒙古河套灌区主要作物油料向日葵为研究对象,进行了田间试验,采用312-D最优饱和试验设计方案,随机排列,2次重复,以产量为目标函数建立了不同盐分水平下的回归模型,并进行分析。研究结果表明,在盐渍化地区土壤中水肥因子的影响效应轻度盐渍化土壤依次为水分、磷、氮,中度盐渍化土壤依次为水分、氮、磷。最佳水肥配比范围轻度灌水量为1 581~2 116 m3/hm2,中度灌水量为1 088~1 549 m3/hm2,氮为225 kg/hm2,磷为150 kg/hm2。  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号