首页 | 官方网站   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   56篇
  免费   7篇
农业科学   63篇
  2023年   2篇
  2022年   2篇
  2021年   2篇
  2020年   3篇
  2019年   2篇
  2018年   4篇
  2017年   4篇
  2016年   6篇
  2015年   3篇
  2014年   2篇
  2013年   5篇
  2012年   5篇
  2011年   4篇
  2010年   2篇
  2009年   1篇
  2008年   6篇
  2007年   2篇
  2006年   2篇
  2003年   2篇
  1990年   1篇
  1986年   1篇
  1984年   2篇
排序方式: 共有63条查询结果,搜索用时 31 毫秒
1.
Landscape Ecology - Several case studies investigated the role of ecosystem services in participatory planning processes. However, no systematic study exists that cuts across a large number of...  相似文献   
2.
Cutaneous leiomyosarcomas are malignant mesenchymal tumors of smooth muscle origin and are reported occasionally in avian species. A 14-y-old male laboratory White Carneau pigeon (Columba livia) was presented for surgical excision of a cervical soft tissue mass. Ultrasonography with color flow Doppler imaging revealed multiple cavitations of mixed echogenicity within the mass and vascularization. Histologically, the dermis and subcutis were expanded by a densely cellular multinodular mass comprised of fusiform cells forming haphazardly arranged broad streams and short interwoven bundles, often surrounding blood vessels and variably sized cavitations. Neoplastic cells were strongly immunopositive for desmin and α–smooth muscle actin, and negative for pancytokeratin, S100, and von Willebrand factor. Based on histopathology and IHC findings, the cutaneous mass was diagnosed as leiomyosarcoma (LMS). The pigeon died 312 d post-operatively. Postmortem examination revealed masses infiltrating the left and right pulmonary airways and one hepatic nodule, but no regrowth at the surgical site. Histologic and IHC evaluation of the pulmonary and hepatic masses were consistent with LMS, representing metastatic foci from the primary cutaneous LMS. Our case highlights the malignant behavior and histomorphologic features of cutaneous LMS in an avian species.  相似文献   
3.
Journal of Plant Diseases and Protection - Citrus (Citrus spp. L.), which has high nutritional and economic value, is one of the most commonly grown fruits in Turkey. In spring 2020, large aerial...  相似文献   
4.
The Tatura system for the preparation of seed-beds for irrigated annual row-crops is described, where the soil is tilled when wet and friable and so requires few passes with implements to become suitable for crops, and where seeds are sown into wet soil. In soil prepared by the Tatura system, the percentage of aggregates < 0.5 mm diameter (as measured by dry-sieving) in the seed-bed was about half that found in commercially prepared seed-beds which were tilled up to 50 times when dry. With the Tatura system, the wetter the soil (up to 22% water content) when tilled, or the more passes (up to 4) of the implement at a water content of 22%, the less dust (< 0.5 mm diameter) and/or fewer clods (> 20 mm diameter) were formed.

The macro-structure of the surface layer of soil tilled at different water contents by the Tatura system was also quantified statistically by the method of wax-impregnation. The macro-structures were compared at the 10 mm, 20 mm, 40 mm, 60 mm and 80 mm depths in beds of soil prepared for irrigated annual row-crops by a system which has been described previously. Within each treatment (21.7%; 19.0%; 11.6% water content at 0–100 mm depth at tillage), the linear porosity and mean pore-size each tended to decrease with depth to 40 mm, with no further change or slight decrease to 80 mm depth. In all treatments, the mean aggregate-size tended to increase with depth from 10 mm depth to 80 mm depth. The sizes of pores and aggregates varied across each bed and possibly depended on the position of tines within the bed at each pass at tillage. Water content at tillage led to small differences in structure of the beds of soil. Soil tilled at a water content slightly above the Casagrande Plastic Limit generally had slightly larger pores and aggregates than soil tilled at lower water contents.  相似文献   

5.
Immunodiagnostic confirmation of cystic human hydatidosis is frequently required before surgical intervention or of chemotherapy. However, it remains inadequate to detect specific antibodies or antigens in some confirmed cases of echinococcosis. This study was carried out to investigate the accuracy of three different immunodiagnostic tests for detection of specific circulating antigens or antibodies in the serum and urine of 13 experimentally infected sheep. For this purpose, Echinococcus granulosus were collected from small intestine of experimentally infected dogs, and 2000 taenid eggs were orally administered to each of the 13 sheep. There were six other sheep, which were kept as the control group. Biweekly serum and urine samples were collected from all the sheep for 4 months after infection. The sera were subjected to indirect hemagglutination test and the concentrated urine samples were subjected to coagglutination and counter immunoelectrophoresis tests. The results revealed that the sensitivity of these tests in detecting the hydatid antigens in the urine or antihydatid antibodies in the serum of the infected sheep reached their maximum in 12th and 13th week after infection; then it decreased in the following weeks. Examination of the non-infected sheep samples throughout the experiment showed that the aforesaid findings were specific only to the infected sheep. It seems that the appearance of specific hydatid antigen in urine and its antibodies in the serum were simultaneous. Although these tests are highly specific, false negative outcomes were encountered in their detection of cystic echinococcosis. In general, it seems rational to establish some series of diagnostic procedures in order to reveal antibodies and antigen of metacestode in serum and urine of the patients.  相似文献   
6.
7.
An evaluation of genetic diversity in 39 wild asparagus populations was carried out using morphological and RAPD markers. A combination of morphological traits and random RAPD primers was used to examine the level of genetic variation and polymorphisms among the populations. A factor analysis using Ward's method on mean values of morphological characteristics indicated seven main factors resulting in four groups. Analysis of polymorphic bands using Jaccard's similarity coefficient indicated that genetic similarity ranged between 0.71 and 0.29. At a similarity level of 0.64, the populations were divided in three sub-clusters, containing 34, four and one populations, respectively. Significant regression associations were found between 21 morphological characteristics and 18 RAPD markers, revealing some informative markers associated with some traits. The highest R2 was related to 18 RAPD markers associated with gender (53.5%) that among them BA-042000 had a maximum R2. The results showed that Iranian wild asparagus with its high levels of genetic variation could be considered as a valuable gene pool for future asparagus breeding programs. Furthermore, it could be inferred that morphological characteristics and RAPD markers are suitable tools to discriminate asparagus populations for the evaluation of genetic diversity.  相似文献   
8.
This study investigates the effects of different temperatures on the total carbohydrate, lipid and protein amounts of Acanthoscelides obtectus Say, which is a common cereal pest. Studies have been carried out under laboratory conditions at 20 +/- 2 degrees C, 30 +/- 2 degrees C and 60 +/- 5% relative humidity. No specific photoperiodic regimen has been used throughout the study. Total carbohydrate, protein and lipid amounts for females at 20 degrees C were 61.74, 35.77 and 83.79 microg/individual, respectively, whereas the amounts for males were 34.94, 29.53 and 57.98 microg/individual, respectively. At 30 degrees C, total carbohydrate, protein and lipid amounts for females were 92.00, 42.18 and 83.26 microg/individual, respectively. The amounts at the same temperature for males were 43.34, 34.08 and 52.19 microg/individual, respectively. In both sexes, total carbohydrate and protein amounts at 30 degrees C were higher than those at 20 degrees C whereas this was not true for total lipid amounts.  相似文献   
9.
Variations in protein and carbohydrate levels correlated with the age and sex of Galleria mellonella (Linnaeus, 1758) (Lepidoptera: Pyralidae) in constant lightness and darkness were investigated. Tests were conducted under laboratory conditions at 28 +/- 2 degrees C temperature and 65 +/- 5% relative humidity. Insects were fed on combs without honey. Protein level in 100 mg of adults increased in the first days of adult life of females in connection with their age and then decreased. No difference was observed in males. Carbohydrate level in 100 mg of adults increased in both sexes in connection with their age. In all tests carbohydrate and protein levels of females were found higher than males. Protein and carbohydrate levels of adult G. mellonella varied in connection with the photoperiod regimes implemented. Decrease in the nutrient levels was observed in constant darkness.  相似文献   
10.
母鸡的日粮可影响蛋壳质量、蛋白浓稠度、蛋黄色泽、血斑、腥味、胆固醇含量、矿物质含量和维生素含量。本介绍了通过营养途径改善食用蛋的方法。  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-23

京公网安备 11010802026262号