全文获取类型
收费全文 | 424篇 |
免费 | 16篇 |
专业分类
林业 | 43篇 |
农学 | 47篇 |
基础科学 | 6篇 |
106篇 | |
综合类 | 20篇 |
农作物 | 37篇 |
水产渔业 | 47篇 |
畜牧兽医 | 85篇 |
园艺 | 5篇 |
植物保护 | 44篇 |
出版年
2023年 | 12篇 |
2022年 | 10篇 |
2021年 | 11篇 |
2020年 | 14篇 |
2019年 | 19篇 |
2018年 | 17篇 |
2017年 | 17篇 |
2016年 | 20篇 |
2015年 | 5篇 |
2014年 | 16篇 |
2013年 | 45篇 |
2012年 | 22篇 |
2011年 | 19篇 |
2010年 | 18篇 |
2009年 | 20篇 |
2008年 | 22篇 |
2007年 | 16篇 |
2006年 | 14篇 |
2005年 | 10篇 |
2004年 | 12篇 |
2003年 | 5篇 |
2002年 | 7篇 |
2001年 | 12篇 |
2000年 | 3篇 |
1999年 | 10篇 |
1998年 | 5篇 |
1997年 | 2篇 |
1994年 | 3篇 |
1993年 | 3篇 |
1992年 | 1篇 |
1990年 | 5篇 |
1989年 | 4篇 |
1988年 | 6篇 |
1987年 | 4篇 |
1986年 | 4篇 |
1985年 | 4篇 |
1984年 | 1篇 |
1983年 | 3篇 |
1982年 | 2篇 |
1981年 | 2篇 |
1980年 | 4篇 |
1979年 | 3篇 |
1977年 | 1篇 |
1976年 | 2篇 |
1971年 | 1篇 |
1967年 | 1篇 |
1966年 | 3篇 |
排序方式: 共有440条查询结果,搜索用时 15 毫秒
31.
Takashi Ozawa Chandra Prasad Risal Ryoko Yanagimoto 《Soil Science and Plant Nutrition》2005,51(6):917-920
The contribution of an earthworm species ( Amynthas vittatus ) to the increase of the nitrogen content of soil was examined. Three specimens of adult earthworms were introduced into 300 g of soil (Gray Lowland soil, silty clay) supplemented with 1% carboxymethyl cellulose in a container and incubated for 32 d at 22°C in the dark. The contents of total-N, NH4 -N and NO3 -N, and the population of aerobic nitrogen-fixing bacteria in soil significantly increased after incubation with the earthworms, while the natural abundance of 15 N (δ15 N) in soil decreased. The amount of nitrogen in the earthworms did not decrease during the incubation in the microcosm. Both acetylene reduction activity of the microcosm and incorporation of 15 N to soil from atmospheric 15 N2 were significantly enhanced by the introduction of the earthworms into soil, though the observed increment of nitrogen in soil was much higher than the estimated one based on the nitrogen-fixing activity. The results obtained in the present study indicated that the earthworms increased the nitrogen content of soil, presumably due to the enhancement of the nitrogen-fixing activity of the soil from the microcosm by the earthworms. 相似文献
32.
Mary Elizabeth K. Gnanambal K. C. Ramya Devi P. Hareesh Chandra Edward J. K. Patterson 《Phytoparasitica》2011,39(2):121-127
The current study is based on the screening of novel insecticides from new sources that have not being exploited hitherto.
The major objectives of this research work were to extract marine molluscs, Lambis lambis, Trochus radiatus and Chicoreus ramosus, from Tuticorin coastal waters using different solvents to test their insecticidal properties and partially purify the active
components. The ethyl acetate extracts of L. lambis and T. radiatus showed 100% mortality of Sitophilus oryzae, at a concentration of 200 μg ml−1. The LC50 values for ethyl acetate extracts of L. lambis, T. radiatus and C. ramosus were found to be 67.08, 348.86 and 571.42 μg ml−1, respectively. With regard to bacterial metabolites, at a concentration of 200 μg ml−1 the ethyl acetate extract of A3 was able to elicit an activity of 40% and that of strain A1 – 20%. The LC50 values of the bacterial metabolites were also investigated. Upon chromatographic separation of active ethyl acetate extracts
of T. radiatus, the 100% methanol column-purified fraction was found to have an activity of 30% at a concentration of 10 μg against S. oryzae. The purity of the partially pure active compound was observed to be 72.78% on analysis with high pressure thin layer chromatography. 相似文献
33.
Naturally derived micelles for rapid in vitro screening of potential cholesterol-lowering bioactives
Kirana C Rogers PF Bennett LE Abeywardena MY Patten GS 《Journal of agricultural and food chemistry》2005,53(11):4623-4627
A high plasma cholesterol level, especially low-density lipoprotein cholesterol, indicates increased risk of cardiovascular diseases. Plasma cholesterol levels are influenced by diet and cholesterol biosynthesis, uptake, and secretion. Cholesterol uptake involves solubilization into complex phospholipid spherical bodies termed micelles that facilitate the transport of lipids through the gut brush border membrane into enterocytes. In vitro assays reported to date to determine potential cholesterol-lowering effects of various compounds require artificial micelle preparations that are elaborate and time-consuming to prepare. The aims of this study were to compare the efficacy of artificially prepared micelles with naturally derived micelles from pig's bile and to test their ability to assess potential inhibitors of cholesterol uptake. The suitability of pig's bile-derived micelles was tested both at the level of the micelle and at cellular uptake using cultured Caco-2 cells. Known cholesterol uptake inhibitors at the micelle (green tea catechins) and at the Caco-2 cell (beta-lactoglobulin-derived peptide, IIAEK) were used as reference inhibitory compounds. It was concluded that pig's bile was a rapid, reproducible, convenient, and cost-effective source of micelles for cholesterol micelle solubility and cellular uptake assay systems and is suitable for screening purposes focused on identifying potential cholesterol-lowering agents. 相似文献
34.
Lakshmi Narasimha Murthy Girija Gajanan Phadke Chitradurga Obaiah Mohan Madhamuthanalli Venkataramappa Chandra Jeyakumari Annamalai Sivam Visnuvinayagam 《Journal Of Aquatic Food Product Technology》2017,26(8):913-928
In the present study, spray-dried pink perch meat protein hydrolysate (PPH) and hydrolysate with maltodextrin and gum arabic (PPHMG) were characterized in relation to their physical, rheological, functional, antioxidant, thermal, and sensory properties. The Herschel–Bulkley model was suitable to explain the flow behavior of PPH and PPHMG emulsions. Both the samples exhibited functional and antioxidant properties. Antioxidant activities were significantly higher for PPH compared with PPHMG (p<0.05). PPH and PPHMG alone did not exhibit antimicrobial activity but enhanced the activity of chitosan against pathogens. Sensory acceptability of the samples in soup revealed that PPHMG of up to 4% was highly scored without any traces of bitterness, whereas for PPH, a concentration of up to 3% was acceptable. 相似文献
35.
R. P. Bansal R. C. Joshi B. Sharma U. Chandra 《Tropical animal health and production》1987,19(1):53-55
Reverse phase passive haemagglutination [RPHA] test was applied for the detection of rinderpest antigen in various organs of rinderpest infected cattle. The results of RPHA were compared with counter immunoelectrophoresis [CIE] and single radial haemolysis [SRH] test. RPHA was as sensitive as CIE and SRH in detecting rinderpest antigen. 相似文献
36.
R. Chandra Babu M. Moosa Sheriff V. Muralidharan M. Seetharani 《Journal of Agronomy and Crop Science》1988,161(5):353-356
Significant differences were observed for leaf net photosynthetic rate, chlorophyll content, soluble protein content, nitrate reductase activity, stomatal frequency and specific leaf mass among ten greengram cultivars. Leaf net photosynthetic rate had significant positive correlation with soluble protein, nitrate reductase activity, stomatal frequency and specific leaf mass. Leaf net photosynthetic rate had no relationship with leaf chlorophyll content in greengram. 相似文献
37.
C. Vijayalakshmi R. Chandra Babu S. R. Sree Rangaswamy 《Journal of Agronomy and Crop Science》1988,161(3):181-184
A field study was conducted to determine if differences in grain filling rate and duration existed in two early cultivars of rice. There is no cultivar difference in duration of grain filling and grain matured in about 30 days from anthesis in both the cultivars. The effective grain filling period in rice is only 10 days between 3rd and 13th day from anthesis. There is significant difference in grain filling rate and is positively related to grain weight. Grain filling rate is more important than duration of filling for achieving higher grain size and thus yield in rice. 相似文献
38.
Identification of readily measured traits that are associated with higher productivity of field crops is important to breeders. The objective of this study was to find out whether pod filling rate or duration of pod filling greatly decide final pod weight in greengram and blackgram. The effective pod filling duration is only 16 days in both the crops. Pod filling rate is more important than duration of pod development. Richards function is found to more closely fit the data on pod development from anthesis to maturity in both the species. 相似文献
39.
M P Yurawecz J Y Chen B J Puma 《Journal of the Association of Official Analytical Chemists》1986,69(4):586-591
The cis- and trans-isomers of 1,1,2,3,4-pentachloro-4-[1-methylethoxy]-1,3-butadiene have been identified as contaminants in fish caught from the Mississippi River at St. Louis, MO, and as far as 150 miles south of that location. Up to 0.1 ppm of the cis-isomer and 0.8 ppm of the trans-isomer were determined by using a method based on the AOAC multiresidue method for detecting organochlorine and organophosphorus pesticides. In tests of the modified AOAC method on spiked fish, both isomers were quantitatively recovered (95-106%). A mixture of the cis- and trans-isomers was synthesized by reacting hexachlorobutadiene with sodium isopropoxide. Separation of the reaction products by Florisil column chromatography provided reference standards of the individual isomers for identification and quantitation of the residues. The stereospecificity of the synthesis reaction and the infrared and mass spectral data used to verify the structures of the products are discussed. 相似文献
40.