全文获取类型
收费全文 | 1502篇 |
免费 | 80篇 |
国内免费 | 154篇 |
专业分类
林业 | 151篇 |
农学 | 114篇 |
基础科学 | 19篇 |
201篇 | |
综合类 | 562篇 |
农作物 | 249篇 |
水产渔业 | 87篇 |
畜牧兽医 | 117篇 |
园艺 | 88篇 |
植物保护 | 148篇 |
出版年
2024年 | 12篇 |
2023年 | 28篇 |
2022年 | 58篇 |
2021年 | 87篇 |
2020年 | 67篇 |
2019年 | 64篇 |
2018年 | 51篇 |
2017年 | 84篇 |
2016年 | 86篇 |
2015年 | 71篇 |
2014年 | 85篇 |
2013年 | 116篇 |
2012年 | 115篇 |
2011年 | 132篇 |
2010年 | 88篇 |
2009年 | 67篇 |
2008年 | 70篇 |
2007年 | 86篇 |
2006年 | 73篇 |
2005年 | 43篇 |
2004年 | 45篇 |
2003年 | 34篇 |
2002年 | 25篇 |
2001年 | 21篇 |
2000年 | 20篇 |
1999年 | 8篇 |
1998年 | 10篇 |
1997年 | 12篇 |
1996年 | 15篇 |
1995年 | 14篇 |
1994年 | 6篇 |
1993年 | 6篇 |
1992年 | 9篇 |
1991年 | 10篇 |
1990年 | 3篇 |
1989年 | 4篇 |
1988年 | 4篇 |
1987年 | 4篇 |
1986年 | 2篇 |
1963年 | 1篇 |
排序方式: 共有1736条查询结果,搜索用时 0 毫秒
991.
992.
993.
Silages containing bioactive forage legumes: a promising protein‐rich feed source for growing lambs 下载免费PDF全文
G. Copani V. Niderkorn F. Anglard A. Quereuil C. Ginane 《Grass and Forage Science》2016,71(4):622-631
Forage legumes that contain secondary compounds are considered to be less susceptible to proteolysis than other legumes, with improved silage quality and possibly improved animal performance. This was investigated feeding five groups of growing lambs for 10 weeks, five silages composed of pure timothy (T; Phleum pratense), mixtures of T with red clover (Trifolium pratense; T‐RC, 50/50 on DM basis), sainfoin (Onobrychis viciifolia; T‐SF), or both (T‐RC‐SF, 50/25/25), or a mixture of the two legumes (RC‐SF). Including SF and/or RC in silages improved silage fermentation as shown by higher lactic acid and lower soluble N and NH3 contents than in T silage. Voluntary intakes were higher with all the RC‐containing silages than with T and T‐SF. The T‐SF silage had the lowest, and RC‐containing silages the highest average values for daily gain, feed conversion efficiency, live weight and carcass weight. The differing effects of these silages cannot be totally explained by differences in their nutritive value and so may be due to their bioactive compounds impacting differently on feeding motivation and digestive efficiency. These results suggest that including RC in silages is a promising strategy to combine improved animal performance with reduced environmental pressure. 相似文献
994.
995.
Marzia Vasarri Manuela Leri Emanuela Barletta Carlo Pretti Donatella DeglInnocenti 《Marine drugs》2021,19(10)
Neuroblastoma (NB) is a common cancer in childhood, and lethal in its high-risk form, primarily because of its high metastatic potential. Targeting cancer cell migration, and thus preventing metastasis formation, is the rationale for more effective cancer therapy against NB. Previous studies have described the leaf extract from Posidonia oceanica marine plant (POE) as an antioxidant, anti-inflammatory agent and inhibitor of cancer cell migration. This study aims to examine the POE anti-migratory role in human SH-SY5Y neuroblastoma cells and the underlying mechanisms of action. Wound healing and gelatin zymography assays showed that POE at early times inhibits cell migration and reduces pro-MMP-2 release into culture medium. By monitoring expression level of key autophagy markers by Western blot assay, a correlation between POE-induced cell migration inhibition and autophagy activation was demonstrated. Cell morphology and immunofluorescence analyses showed that POE induces neurite formation and neuronal differentiation at later times. These results suggest POE might act against cell migration by triggering early nontoxic autophagy. The POE-induced cellular morphological change toward cell differentiation might contribute to prolonging the phytocomplex anti-migratory effect to later times. Overall, these results encourage future in vivo studies to test POE applicability in neuroblastoma treatment. 相似文献
996.
Helena M. Amaro Rita Barros Tnia Tavares Raquel Almeida Isabel Sousa Pinto Francisco Xavier Malcata Ana Catarina Guedes 《Marine drugs》2021,19(11)
Bioactive lipidic compounds of microalgae, such as polyunsaturated fatty acids (PUFA) and carotenoids, can avoid or treat oxidation-associated conditions and diseases like inflammation or cancer. This study aimed to assess the bioactive potential of lipidic extracts obtained from Gloeothece sp.–using Generally Recognized as Safe (GRAS) solvents like ethanol, acetone, hexane:isopropanol (3:2) (HI) and ethyl lactate. The bioactive potential of extracts was assessed in terms of antioxidant (ABTS•+, DPPH•, •NO and O2•assays), anti-inflammatory (HRBC membrane stabilization and Cox-2 screening assay), and antitumor capacity (death by TUNEL, and anti-proliferative by BrdU incorporation assay in AGS cancer cells); while its composition was characterized in terms of carotenoids and fatty acids, by HPLC-DAD and GC-FID methods, respectively. Results revealed a chemopreventive potential of the HI extract owing to its ability to: (I) scavenge -NO• radical (IC50, 1258 ± 0.353 µg·mL−1); (II) inhibit 50% of COX-2 expression at 130.2 ± 7.4 µg·mL−1; (III) protect 61.6 ± 9.2% of lysosomes from heat damage, and (IV) induce AGS cell death by 4.2-fold and avoid its proliferation up to 40% in a concentration of 23.2 ± 1.9 µg·mL−1. Hence, Gloeothece sp. extracts, namely HI, were revealed to have the potential to be used for nutraceutical purposes. 相似文献
997.
Natalia Castejn Kristin Anna Thorarinsdottir Ragnhildur Einarsdttir Kristberg Kristbergsson Gudrún Marteinsdttir 《Marine drugs》2021,19(12)
A growing concern for overall health is driving a global market of natural ingredients not only in the food industry but also in the cosmetic field. In this study, a screening on potential cosmetic applications of aqueous extracts from three Icelandic seaweeds produced by pulsed electric fields (PEF) was performed. Produced extracts by PEF from Ulva lactuca, Alaria esculenta and Palmaria palmata were compared with the traditional hot water extraction in terms of polyphenol, flavonoid and carbohydrate content. Moreover, antioxidant properties and enzymatic inhibitory activities were evaluated by using in vitro assays. PEF exhibited similar results to the traditional method, showing several advantages such as its non-thermal nature and shorter extraction time. Amongst the three Icelandic species, Alaria esculenta showed the highest content of phenolic (mean value 8869.7 µg GAE/g dw) and flavonoid (mean value 12,098.7 µg QE/g dw) compounds, also exhibiting the highest antioxidant capacities. Moreover, Alaria esculenta extracts exhibited excellent anti-enzymatic activities (76.9, 72.8, 93.0 and 100% for collagenase, elastase, tyrosinase and hyaluronidase, respectively) for their use in skin whitening and anti-aging products. Thus, our preliminary study suggests that Icelandic Alaria esculenta-based extracts produced by PEF could be used as potential ingredients for natural cosmetic and cosmeceutical formulations. 相似文献
998.
以干燥过程中龙眼酚类物质及多糖为研究对象,考察其含量和抗氧化活性在热泵干燥过程中的变化规律。结果表明,干燥过程中,龙眼游离酚、总酚和多糖的含量显著下降,分别下降了27.61%、23.94%和73.17%。结合酚含量显著升高,升高了111.11%。指数衰减模型能有效地拟合干燥过程中龙眼游离酚、总酚和多糖的含量变化曲线,S曲线则更适合于描述结合酚含量的变化规律。龙眼游离酚、结合酚和多糖的DPPH自由基清除能力在干燥过程中分别呈现下降、上升和下降的趋势。其中多糖的DPPH自由基清除能力的下降主要集中在干燥24 h和30 h之间。干燥过程中,龙眼中游离酚、结合酚、总酚及多糖的含量与其对应的抗氧化性均呈显著正相关。 相似文献
999.
Jia-Run Han Yi-Nan Du Yue Tang Jun Zhao Wen-Hui Shang Jia-Nan Yan 《Journal Of Aquatic Food Product Technology》2019,28(4):352-364
In order to improve the utilization of scallop byproducts, scallop female gonad hydrolysates (SFGHs) were prepared using alcalase and ribose at a mass ratio of 1:2 and pH 7.0 (95°C, up to 12 h) to develop heterogeneous Maillard-type antioxidant and flavor compounds. The formation of Schiff’s base as well as modification of the amide bands in Maillard reaction products (MRPs) were investigated using ultraviolet–visible, fluorescence, and Fourier transform infrared spectroscopy. The significant decrease of amino acid residues explained the strong Maillard reactivity of SFGHs. MRPs with enhanced ABTS+ radical scavenging capacity over SFGHs promoted the survival of HepG2 cells treated with hydrogen peroxide. Moreover, 19 new volatile compounds were produced by the reaction of SFGHs with ribose. These results suggest that SFGHs–ribose MRPs can be potentially used as antioxidants with flavor properties.
Abbreviations: SFGs: scallop female gonads; SFGHs: scallop female gonad hydrolysates; ABTS: 2?2-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid); BHT: butylated hydroxytoluene; Trolox: 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid; MRPs: Maillard reaction product; H2O2: hydrogen peroxide; HS-SPME/GC/MS: Headspace solid phase micro-extraction/gas chromatography/mass spectrometry. 相似文献
1000.
利用中药重楼内生菌解决其药用资源紧缺的研究前景 总被引:1,自引:0,他引:1
中药重楼化学成分复杂,药理活性强,临床应用范围广,是"云南白药"等多种中成药的主要原料之一.由于重楼生长周期长、价格居高不下,加之对该药狂采滥挖,重楼已成国家重点保护的濒危物种,该资源的有效保护和合理利用势在必行.药用植物内生菌次生代谢产物的测定结果证实了内生菌能够产生与宿主植物相同或相似的药用活性成分,中药内生菌资源... 相似文献