全文获取类型
收费全文 | 1223篇 |
免费 | 54篇 |
专业分类
林业 | 60篇 |
农学 | 45篇 |
基础科学 | 17篇 |
245篇 | |
综合类 | 40篇 |
农作物 | 133篇 |
水产渔业 | 126篇 |
畜牧兽医 | 414篇 |
园艺 | 46篇 |
植物保护 | 151篇 |
出版年
2023年 | 14篇 |
2022年 | 37篇 |
2021年 | 58篇 |
2020年 | 56篇 |
2019年 | 82篇 |
2018年 | 52篇 |
2017年 | 78篇 |
2016年 | 59篇 |
2015年 | 42篇 |
2014年 | 48篇 |
2013年 | 90篇 |
2012年 | 78篇 |
2011年 | 77篇 |
2010年 | 52篇 |
2009年 | 40篇 |
2008年 | 47篇 |
2007年 | 36篇 |
2006年 | 42篇 |
2005年 | 46篇 |
2004年 | 31篇 |
2003年 | 21篇 |
2002年 | 31篇 |
2001年 | 10篇 |
2000年 | 10篇 |
1999年 | 14篇 |
1998年 | 5篇 |
1997年 | 9篇 |
1996年 | 3篇 |
1995年 | 6篇 |
1994年 | 5篇 |
1993年 | 7篇 |
1992年 | 5篇 |
1991年 | 6篇 |
1990年 | 10篇 |
1989年 | 6篇 |
1988年 | 4篇 |
1987年 | 7篇 |
1986年 | 3篇 |
1985年 | 6篇 |
1984年 | 7篇 |
1983年 | 4篇 |
1982年 | 3篇 |
1977年 | 3篇 |
1976年 | 2篇 |
1975年 | 4篇 |
1974年 | 3篇 |
1971年 | 2篇 |
1970年 | 2篇 |
1969年 | 3篇 |
1967年 | 2篇 |
排序方式: 共有1277条查询结果,搜索用时 171 毫秒
941.
de la Luz Cádiz-Gurrea María Fernández de las Nieves Ignacio Aguilera Saez Luis Manuel Fernández-Arroyo Salvador Legeai-Mallet Laurence Bouaziz Mohamed Segura-Carretero Antonio 《Plant foods for human nutrition (Dordrecht, Netherlands)》2019,74(1):40-46
Plant Foods for Human Nutrition - Plants, including most food and feed plants, produce a broad range of bioactive chemical compounds. Among these compounds, polyphenols are reported to provide... 相似文献
942.
Yasir Serag Alnor Mohammed Izzat Sidahmed Ali Tahir Nasrein Mohamed Kamal Amin Elsadig Eltayeb Abdelbagi Mukhtar Ali Hisashi Tsujimoto 《Breeding Science》2014,63(5):450-460
Adaptation of wheat (Triticum aestivum L.) to high temperatures could be improved by introducing alien genes from wild relatives. We evaluated the responses of wheat-Leymus racemosus chromosome introgression lines to high temperature to determine their potentiality for developing improved wheat cultivars. Introgression lines and their parent Chinese Spring were evaluated in a growth chamber at the seedling stage and in the field at the reproductive stage in two heat-stressed environments in Sudan. Optimum and late planting were used to ensure exposure of the plants to heat stress at the reproductive stage. The results revealed the impact of several Leymus chromosomes in improving wheat adaptation and tolerance to heat. Three lines possessed enhanced adaptation, whereas two showed high heat tolerance. Two addition lines showed a large number of kernels per spike, while one possessed high yield potential. Grain yield was correlated negatively with the heat susceptibility index, days to heading and maturity and positively with kernel number per spike and triphenyl tetrazolium chloride assay under late planting. The findings suggest that these genetic stocks could be used as a bridge to introduce the valuable Leymus traits into a superior wheat genetic background, thus helping maximize wheat yield in heat-stressed environments. 相似文献
943.
The genetic diversity and population structure of two Tunisian Thymus species (Thymus algeriensis and Thymus capitatus), from 46 natural populations growing in six bioclimates, were analysed by starch gel electrophoresis using eight isozymes. The genetic diversity within populations varied at species level. Variation in T. algeriensis was higher than that observed for T. capitatus, and exclusive alleles were detected for the two studied species. A high differentiation among populations, for each species, estimated by Wright's F-statistics was revealed. In each species, a high level of inbreeding within populations induced by Wahlund effect was observed. A relatively high level of differentiation associated with a restricted gene flow among species was revealed. The PCA and UPGMA analysis, performed on all populations, showed two distinct groups with respect of specific differentiation level. The high genetic divergence between the two species corroborates their taxonomic status, as previously reported using morphological traits. The strategy for the management and conservation of populations should be made for each taxa according to its level of diversity and bioclimate. 相似文献
944.
Rafaat M. ElsanhotyI.A. Al-Turki Mohamed Fawzy Ramadan 《Industrial Crops and Products》2012,36(1):313-320
This work was conducted to use palm date wastes in the production of carotenoids. Three strains of Lactobacillus plantarum (QS1, QS2 and QS3) were isolated from food samples including bakery's yeast, olive fermentation and cheese. Strains were investigated for their structural recA gene by PCR. The recA gene was successfully amplified from all strains under study. The ability of isolated L. plantarum strains to produce carotenoids in MRS broth was investigated. QS3 isolate gave the highest ability for production of carotenoids. Statistical screening of media components for production of carotenoids by L. plantarum QS3 using date syrup as a source of sugar was carried out using Plackett-Burman design. Date syrup at 5% sugar concentration produced 16.21 mg/kg dry cell of carotenoids when used alone. Increase in carotenoids production was recovered (54.89 mg/kg dry cell) with supplementation of MRS medium with salts and organic nitrogen after optimization of pH and temperature using date syrup as a carbon source. Plackett-Burman design showed peptone, K2HPO4, sodium acetate and date juice as main components affecting carotenoids production. 相似文献
945.
The full whole culture (FWC), containing parasporal protein toxins of Bacillus thuringiensis israelinsis (Bti) and Bacillus sphaericus 2362 (Bs), either singly or in combination with plant oils and commercial insecticides, was tested against larval and adult stages of Culex pipiens mosquitoes under controlled laboratory conditions. In terms of LC50 values recorded after 24, 48, 72 and 96 h, the bacterial toxins showed high potency towards both larvae and adults of mosquitoes in a dose-dependent manner. Generally, the Bti toxin seemed to be more potent than the Bs toxin. For example, the Bti toxin showed a 24 h LC50 of 8.2 ppm against mosquito larvae compared to 13.6 ppm for the Bs toxin. In the adult bioassay, the obtained 24 h LC50 values were 0.064 and 0.085 mg/cm2, respectively for the two bacterial toxins. The bacterial toxins mixed with plant oils or insecticides at equitoxic doses (e.g., LC25 values) mostly showed potentiation effects, either against larvae or adults of the tested insect. Among a total of 14 paired mixtures, only the joint action estimated for the mixture of malathion + Bti or Bs was accounted as additively. Combining Bti or Bs endotoxins at LC0 with different plant oils and insecticides at LC50 concentration levels each, has resulted in considerable synergism against either larvae or adults. In the case of larval bioassays, the maximum synergistic factor (SF) obtained (ca. 2.0) was entitled to the mixture of Bti + spinosad. In the adult bioassays, the mixtures containing Curcuma longa or Melia azedarach oil extracts with Bti or Bs toxins achieved a SF accounted to 2.0. The results of the present study may be considered as an additional contribution to the area of joint toxicity of biocidal agents combining bacterial toxins, plant oils and traditional insecticides. The reached findings may encourage future research to elucidate its performance under practical field conditions. 相似文献
946.
Soil erosion by water is a common environmental problem which can affect the sustainable development and the agriculture of
developing countries especially. Therefore, several countries, threatened by this phenomenon, adopt different measures to
preserve and protect their natural resources. The main purpose of this study was to identify vulnerable areas to establish
a soil erosion risk map in Tunisia. In order to do so, an approach based on a combination of the Revised Universal Soil Loss
Equation (RUSLE) as an erosion model, Geographic Information System (GIS) and Remote Sensing was applied. RUSLE, which is
a model to predict soil loss, is composed of five factors. Erosivity factor (R factor), erodibility factor (K factor), topography factor (LS factor), crop management factor (C factor), and supporting practices factor (P factor). Furthermore, in order to get the most accurate C factor for each land use, times series Moderate Resolution Imaging Spectroradiometer Enhanced Vegetation index (MODIS-EVI)
were used. MODIS-EVI time series was helpful for distinguishing vegetation dynamics with taking into account phenological
variation of the crops. The results indicated that Tunisia has a serious risk of soil erosion. Indeed, about 24.57% of our
study area had a soil loss rate more than 30 t/ha. In these areas, suitable and urgent measures and treatments should be required.
Finally, this approach which is based on remote sensing techniques, GIS and erosion model can be useful for planning appropriate
environmental decision-making policy in a global scale. 相似文献
947.
Hegazy ME Gamal Eldeen AM Shahat AA Abdel-Latif FF Mohamed TA Whittlesey BR Paré PW 《Marine drugs》2012,10(1):209-222
A chemical investigation of an ethyl acetate extract of the Red Sea soft coral Sarcophyton glaucum has led to the isolation of two peroxide diterpenes, 11(S) hydroperoxylsarcoph-12(20)-ene (1), and 12(S)-hydroperoxylsarcoph-10-ene (2), as well as 8-epi-sarcophinone (3). In addition to these three new compounds, two known structures were identified including: ent-sarcophine (4) and sarcophine (5). Structures were elucidated by spectroscopic analysis, with the relative configuration of 1 and 2 confirmed by X-ray diffraction. Isolated compounds were found to be inhibitors of cytochrome P450 1A activity as well as inducers of glutathione S-transferases (GST), quinone reductase (QR), and epoxide hydrolase (mEH) establishing chemo-preventive and tumor anti-initiating activity for these characterized metabolites. 相似文献
948.
949.
Mohamed R. Akl Nehad M. Ayoub Hassan Y. Ebrahim Mohamed M. Mohyeldin Khaled Y. Orabi Ahmed I. Foudah Khalid A. El Sayed 《Marine drugs》2015,13(1):288-311
Receptor tyrosine kinases are key regulators of cellular growth and proliferation. Dysregulations of receptor tyrosine kinases in cancer cells may promote tumorigenesis by multiple mechanisms including enhanced cell survival and inhibition of cell death. Araguspongines represent a group of macrocyclic oxaquinolizidine alkaloids isolated from the marine sponge Xestospongia species. This study evaluated the anticancer activity of the known oxaquinolizidine alkaloids araguspongines A, C, K and L, and xestospongin B against breast cancer cells. Araguspongine C inhibited the proliferation of multiple breast cancer cell lines in vitro in a dose-dependent manner. Interestingly, araguspongine C-induced autophagic cell death in HER2-overexpressing BT-474 breast cancer cells was characterized by vacuole formation and upregulation of autophagy markers including LC3A/B, Atg3, Atg7, and Atg16L. Araguspongine C-induced autophagy was associated with suppression of c-Met and HER2 receptor tyrosine kinase activation. Further in-silico docking studies and cell-free Z-LYTE assays indicated the potential of direct interaction between araguspongine C and the receptor tyrosine kinases c-Met and HER2 at their kinase domains. Remarkably, araguspongine C treatment resulted in the suppression of PI3K/Akt/mTOR signaling cascade in breast cancer cells undergoing autophagy. Induction of autophagic death in BT-474 cells was also associated with decreased levels of inositol 1,4,5-trisphosphate receptor upon treatment with effective concentration of araguspongine C. In conclusion, results of this study are the first to reveal the potential of araguspongine C as an inhibitor to receptor tyrosine kinases resulting in the induction of autophagic cell death in breast cancer cells. 相似文献
950.
Genetic variation in target‐site resistance to pyrethroids and pirimicarb in Tunisian populations of the peach potato aphid,Myzus persicae (Sulzer) (Hemiptera: Aphididae) 下载免费PDF全文
Kamel Charaabi Sonia Boukhris‐Bouhachem Mohamed Makni Brian Fenton Ian Denholm 《Pest management science》2016,72(12):2313-2320