全文获取类型
收费全文 | 597篇 |
免费 | 41篇 |
专业分类
林业 | 98篇 |
农学 | 25篇 |
基础科学 | 4篇 |
86篇 | |
综合类 | 19篇 |
农作物 | 28篇 |
水产渔业 | 65篇 |
畜牧兽医 | 265篇 |
园艺 | 5篇 |
植物保护 | 43篇 |
出版年
2023年 | 6篇 |
2022年 | 8篇 |
2021年 | 18篇 |
2020年 | 36篇 |
2019年 | 31篇 |
2018年 | 27篇 |
2017年 | 21篇 |
2016年 | 30篇 |
2015年 | 17篇 |
2014年 | 25篇 |
2013年 | 44篇 |
2012年 | 40篇 |
2011年 | 30篇 |
2010年 | 21篇 |
2009年 | 16篇 |
2008年 | 29篇 |
2007年 | 36篇 |
2006年 | 31篇 |
2005年 | 23篇 |
2004年 | 16篇 |
2003年 | 10篇 |
2002年 | 15篇 |
2001年 | 15篇 |
2000年 | 12篇 |
1999年 | 7篇 |
1998年 | 1篇 |
1997年 | 11篇 |
1996年 | 1篇 |
1995年 | 3篇 |
1994年 | 2篇 |
1993年 | 1篇 |
1992年 | 11篇 |
1991年 | 8篇 |
1990年 | 5篇 |
1989年 | 3篇 |
1988年 | 2篇 |
1987年 | 3篇 |
1986年 | 4篇 |
1985年 | 4篇 |
1983年 | 1篇 |
1981年 | 2篇 |
1980年 | 1篇 |
1979年 | 2篇 |
1978年 | 3篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1974年 | 1篇 |
1969年 | 1篇 |
1968年 | 2篇 |
排序方式: 共有638条查询结果,搜索用时 31 毫秒
121.
Atiqur Rahman Barbhuiya Ayyanadar Arunachalam Prabhat Chandra Nath Mohammed Latif Khan Kusum Arunachalam 《Journal of Forest Research》2008,13(1):25-34
Rates of weight loss and nutrient (N and P) release patterns were studied in the leaf litter of the dominant tree species
(Ailanthus grandis, Altingia excelsa, Castanopsis indica, Duabanga sonneriatioides, Dysoxylum binectariferum, Mesua ferrea,
Shorea assamica, Taluma hodgsonii, Terminalia myriocarpa and Vatica lancefolia) of a tropical wet evergreen forest of northeast India. Nitrogen and phosphorus mineralization rate and decay pattern varied
significantly from species to species. In general, the decay pattern, characterized by using a composite polynomial regression
equation, exhibited three distinct phases of decay during litter decomposition—an initial slow decay phase (0.063% weight
loss day−1), followed by a rapid decay phase (0.494% weight loss day−1) and a final slow decay phase (0.136% weight loss day−1). The initial chemical composition of the litter affected decomposition rates and patterns. Species like D. sonneriatoides, D. binectariferum, and T. hodgsonii with higher N and P content, lower carbon and lignin content, and lower C:N ratio and lignin:N ratio exhibited relatively
faster decomposition rates than the other species, for example M. ferrea, C. indica and A. grandis. A slow decay rate was recorded for species such as M. ferrea, C. indica, and A. grandis. The initial N and P content of litter showed significant positive correlations with decay rates. Carbon and lignin content,
lignin:N, and C:N showed significant negative correlations with decay rates. Soil total N and P, and rainfall, soil temperature,
and soil moisture had positive correlations with decay rates. The rapid decomposition rates observed in comparison with other
different forest litter decay rates confirm that tropical wet evergreen forest species are characterized by faster decomposition
rates, indicating a faster rate of organic matter turnover and rapid nutrient cycling. 相似文献
122.
A laboratory study assessed the contact toxicity of indoxacarb, abamectin, endosulfan, insecticidal soap, S-kinoprene and dimethoate to Amblyseius fallacis (Garman), Phytoseiulus persimilis Athias-Henriot and nymphs of Orius insidiosus (Say). Amblyseius fallacis is a predacious phytoseiid mite and an integral part of integrated pest management (IPM) programmes in North American apple orchards. The other two beneficials are widely used in greenhouses to manage various arthropod pests infesting vegetable and ornamental crops. Indoxacarb is a slow-acting insecticide, so toxicity data were recorded 7 days post-treatment when the data had stabilised. It showed no toxicity to O. insidiosus nymphs or to A. fallacis or P. persimilis adults. The LC50 values for O. insidiosus nymphs and P. persimilis could not be estimated with their associated confidence limits, because the g values were greater than 0.5 and under such circumstances the lethal concentration would lie outside the limits. The LC50 for A. fallacis was 7.6x the label rate. The fecundity of P. persimilis was reduced by 26.7%. The eclosion of treated eggs from both species of beneficial mites was not affected adversely. Among the other pest control products, S-kinoprene and endosulfan affected adversely at least one species of the predators, whereas dimethoate, abamectin and insecticidal soap were very toxic to all three beneficials. Indoxacarb should be evaluated as a pest control product in IPM programmes. 相似文献
123.
R. S. Barwick H. O. Mohammed M. E. White R. B. Bryant 《Biology and Fertility of Soils》2000,31(5):385-390
The flotation procedure for the detection of Cryptosporidium parvum and Cryptosporidium muris oocysts in feces was adapted for use on soil samples. Soil samples were seeded with known amounts of purified C. parvum or C. muris oocysts and Cryptosporidium spp.-free bovine feces. The limit of detection for this procedure was determined at different levels of inoculation for each
species. At each level of inoculation, 30 control samples were processed and the observer was blind to the status of the sample.
All samples were examined for the presence of Cryptosporidium spp. oocysts using phase-contrast microscopy. The samples were seeded with the following estimated counts of C. parvum oocysts: 1000/g, 1250/g, and 1500/g. These levels had sensitivities of 88%, 90%, and 93%, respectively. All inoculation levels
had a specificity of 100%. Thirty additional samples were inoculated with C. muris and the limit of detection was found to be 76 oocysts/g sample, with a sensitivity of 97% and a specificity of 100%.
Received: 4 October 1999 相似文献
124.
Photosynthetic light acclimation in red pine (Pinus resinosa Ait.) seedlings was examined in a greenhouse study to better understand the physiological response of this species to increased light intensity following release from competition. Seedlings grown in a high (HL), medium (ML) or low (LL) light environment for 12 weeks were transferred to high light. Gas exchange and chlorophyll fluorescence of ML and LL seedlings were measured prior to and following transfer and compared with the HL control treatment. Photosynthetic characteristics were related to initial light treatment and time after transfer. Acclimation of gas exchange features to high light in shade formed ML and LL foliage was relatively rapid, with similar values among light treatments within 57 days of transfer. Acclimation of net photosynthetic rate was similar in ML and LL seedlings, and was associated primarily with increased mesophyll conductance to CO2. The ratio of variable to maximal chlorophyll fluorescence (Fv/Fm) decreased initially after transfer, especially in LL seedlings, but recovered to normal values after 57 days. Red pine seedlings appear to be well adapted for photosynthetic acclimation to high light intensity, consistent with that reported for other early successional tree species. 相似文献
125.
鸡传染性法氏囊病毒JS株毒力测定 总被引:3,自引:0,他引:3
35日龄SPF鸡半数致死量(LD50)和9日龄SPF鸡胚半数致死量(ELD50)试验结果显示,传染性法氏囊病毒(1BDV)JS株的LD50为10-3.60.1 mL/只,ELD50为10-5.20.1 mL/胚;1~6周龄SPF鸡及商品鸡的致病性试验结果显示,IBDV JS株对SPF鸡和商品鸡3周龄后的致病率为100%,最高致死率分别为93.75%和75%;应用RT-PCR方法从IBDV JS株中扩增的VP2基因,经序列测定分析结果显示,IBDV JS株的VP2基因与香港HK46、日本OKYM、英国UK661等国际超强毒株的氨基酸序列的同源性达99%以上.表明IBDV JS株为超强毒株. 相似文献
126.
Effect of adding different levels of rumen protected choline to the diet on productive and reproductive performance of female goats and growth of their kids from birthing to weaning
下载免费PDF全文
![点击此处可从《Animal Science Journal》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Alsaied A. Habeeb Ahmed E. Gad Mostafa A. Atta Mohammed M. Mustafa 《Animal Science Journal》2018,89(2):348-358
Forty female goats in the third parity were randomly divided into four similar groups. The experiment was started 20 days before mating and lasted until the end of the suckling period for 60 days and weaning their kids. The first group were fed diet without supplementation and kept as control while in the second, third and fourth groups, each doe was fed diets with rumen protected choline (RPC) at the rate of 10, 20 and 40 g/day, respectively. Results showed that number of doe kidding twins and triplets and litter weight of kids born per group increased with increasing the level of RPC in the diet of goats and viability rate of born kids during the suckling period improved due to RPC supplementation in the diets of their mothers. Duration of estrous, days from weaning to estrous, days from kidding to estrous and kidding interval decreased significantly, while conception rate increased due to adding RPC. Milk choline concentrations and total choline secretion though milk were progressively increased significantly with increasing the level of RPC supplementation. Live body weight and daily body gain of their suckling male and female kids at weaning increased significantly with increasing RPC levels in the diets of their mothers. 相似文献
127.
The role of several species of ants as intermediate hosts for poultry cestodes in the Sudan was investigated by a search for cysticercoids in specimens from poultry houses in various localities in the country. Pachycondyla sennaarensis, Messor galla and Acantholepis sp. were the only species collected from the areas surveyed. All these ants were examined for cysticercoids of poultry tapeworms but only P. sennaarensis was found to carry cysticercoids, all of which were identical to those of the poultry cestode, Raillietina tetragona. This tapeworm was recovered from all chicks fed the cysticercoids obtained from P. sennaarensis. R. tetragona cysticercoids were present in 63.3% of the P. sennaarensis sampled with 1–40 cysticercoids per ant, which is the heaviest recorded infestation of an ant species with these cysticeroids. 相似文献
128.
Ayele Shashie Urge Mengistu Animut Getachew Yusuf Mohammed 《Tropical animal health and production》2019,51(1):187-198
Tropical Animal Health and Production - A study was conducted to compare carcass and noncarcass yield, carcass composition, conformation, and fat depot partitioning of three Ethiopian fat-tailed... 相似文献
129.
Moutik Sana Lakram Nazha Bendaou Mohammed Maadoudi El Haj Kabbour Mohammed Rachid Douaik Ahmed Zouahri Abdelmajid El Housni Abdellah Es-Safi Nour Eddine 《Tropical animal health and production》2019,51(8):2437-2445
Tropical Animal Health and Production - The objective of this work was to study the effect of the incorporation of argane by-products (meal and pulp) in ewe’s diet on the production and... 相似文献
130.
Nourrddine Chafik Mohammed Mansour Btissam Elamrani Karl‐Werner Schramm Antonius Kettrup M Khalid Elamrani 《Pest management science》2001,57(6):527-530
The photochemical fate of the herbicide triflusulfuron‐methyl in aqueous solution under UV light (λ > 290 nm) was investigated. Nine photoproducts were detected and tentatively identified by LC/MS and LC/MS/MS analysis. The main routes of degradation involve the cleavage and/or contraction of the sulfonylurea bridge with the elimination of sulfur dioxide, which increases the acidity of the reaction medium. On the basis of the results obtained a photodegradation pathway is proposed. © 2001 Society of Chemical Industry 相似文献