全文获取类型
收费全文 | 3330篇 |
免费 | 245篇 |
国内免费 | 245篇 |
出版年
2023年 | 68篇 |
2022年 | 51篇 |
2021年 | 97篇 |
2020年 | 111篇 |
2019年 | 138篇 |
2018年 | 97篇 |
2017年 | 155篇 |
2016年 | 144篇 |
2015年 | 110篇 |
2014年 | 140篇 |
2013年 | 288篇 |
2012年 | 120篇 |
2011年 | 192篇 |
2010年 | 117篇 |
2009年 | 163篇 |
2008年 | 171篇 |
2007年 | 197篇 |
2006年 | 166篇 |
2005年 | 157篇 |
2004年 | 93篇 |
2003年 | 99篇 |
2002年 | 106篇 |
2001年 | 80篇 |
2000年 | 73篇 |
1999年 | 58篇 |
1998年 | 52篇 |
1997年 | 53篇 |
1996年 | 45篇 |
1995年 | 46篇 |
1994年 | 42篇 |
1993年 | 34篇 |
1992年 | 44篇 |
1991年 | 35篇 |
1990年 | 33篇 |
1989年 | 23篇 |
1988年 | 19篇 |
1987年 | 18篇 |
1986年 | 23篇 |
1985年 | 20篇 |
1984年 | 24篇 |
1982年 | 10篇 |
1981年 | 15篇 |
1980年 | 14篇 |
1979年 | 12篇 |
1978年 | 7篇 |
1977年 | 15篇 |
1976年 | 7篇 |
1975年 | 10篇 |
1974年 | 12篇 |
1973年 | 6篇 |
排序方式: 共有3820条查询结果,搜索用时 31 毫秒
11.
D.A.M. da Silva M.S. Fernandes E.H. Endo A.C.P. Vital E.A. Britta M.E. Favero J.C. Castro P.T. Matumoto-Pintro B.P. Dias Filho C.V. Nakamura M. Machinski Junior J.M.G. Mikcha B.A. de Abreu Filho 《Letters in applied microbiology》2021,72(1):41-52
The use of rosemary essential oil (RO) and its combination with nisin (RO+N) in preventing the multiplication of Alicyclobacillus acidoterrestris in orange juice was evaluated. The minimum inhibitory and bactericidal concentrations (MIC and MBC) for RO were both 125 μg ml−1 while RO+N displayed a synergistic effect. The use of RO and RO+N at concentrations of 1, 4 and 8× MIC in orange juice for 96 h was evaluated in terms of their sporicidal effectiveness. With regard to the action against A. acidoterrestris spores, RO at 8× MIC was sporostatic, whereas RO+N at 1× MIC was sporicidal. Morphological changes in the structure of the micro-organism after treatment were also observed by microscopy. Furthermore, flow cytometric analysis showed that most cells were damaged or killed after treatment. In general, the antioxidant activity after addition of RO+N decreased with time. The results demonstrate that using the combination of RO and nisin can prevent the A. acidoterrestris growth in orange juice. 相似文献
12.
Solidago is a genus of more than 120 species of flowering plants in the Asteraceae family and mainly distributed in Americas. To explore the differences of volatile components and analyze their correlations as well variability among the five species (Solidago caesia, Solidago tortifolia, Solidago glomerata, Solidago nemoralis and Solidago rugosa) of this genus, their volatile components were determined by gas chromatography-mass spectrometry (GC-MS) and then the principal component analysis (PCA) was carried out with PAST (PAST2.08). The results indicated that Solidago caesia almost characterized by the same chemotype with Solidago glomerata due to their common essential oil compositions b-cubebene, (1R)-(+)-α-pinene and (−)-a-cadinol while Solidago nemoralis has little variability with Solidago rugosa and with the presence of germacrene D, limonene and sabenene as the representative compounds. But there is chemical variability between Solidago tortifolia and other four species. Sabenene and πcalacorene are the major volatile compounds of Solidago tortifolia. 相似文献
13.
14.
Ting‐Hang Liu Chia‐Lin Chyan Feng‐Yin Li Ying‐Jie Chen Jason T. C. Tzen 《Biotechnology progress》2011,27(6):1760-1767
It has been demonstrated that caleosin alone is sufficient to stabilize artificial oil bodies. A series of recombinant caleosins, mutated with 3, 5, 8, 11, 13, 15, and 17 extra Lys residues and over‐expressed in Escherichia coli, were used as carrier proteins to render biotin as a hapten on the surface of artificial oil bodies for antibody production. Biotinylation levels of the recombinant caleosins were step‐wisely elevated as the number of extra Lys residues increased, and the biotinylated Lys residues were identified by mass spectrometric analysis. Polyclonal antibodies against biotin were successfully generated in rats injected with artificial oil bodies constituted with each of the biotinylated caleosins. Moreover, those generated via the biotinylated caleosins with eight or more extra Lys residues no longer recognized caleosin. It appears that engineered Lys‐rich caleosins are suitable carrier proteins for the production of antibodies against small molecules. © 2011 American Institute of Chemical Engineers Biotechnol. Prog., 2011 相似文献
15.
《Animal : an international journal of animal bioscience》2016,10(1):19-24
The objective of this experiment was to replace soya bean oil with glycerol in laying hen diets and assess the change’s effect on performance, parameters of egg quality and the egg fatty acid profile. A total of 60 44-week-old Hy-Line W36 laying hens were distributed according to a completely randomised experimental design into four treatments consisting of glycerol substitutions for soya bean oil dietary at varying inclusion levels (0%, 25%, 50% and 75%), with five replicates of three birds each. Dietary treatments had no significant effect on BW change, egg production, feed intake, feed conversion ratio, egg weight and egg mass of laying hens. The inclusion of glycerol in the diet of laying hens had no significant effect on egg specific gravity, eggshell breaking strength, eggshell weight, eggshell thickness, egg shape index, albumen index, yolk index, haugh unit, albumen pH, yolk pH and egg yolk colour values. The inclusion of glycerol in the diet of laying hens had no significant effect on palmitic, palmitoleic, stearic, oleic and linolenic acid contents of the egg yolk. The linoleic acid and polyunsaturated fatty acid contents of the egg yolk significantly decreased with the higher levels of dietary glycerol supplementation (P<0.05). The results of this study show that it is possible to replace 75% of soya bean oil (4.5% in diet) with glycerol. 相似文献
16.
Laura Santagostini Elisabetta Caporali Claudia Giuliani Martina Bottoni Roberta Ascrizzi Silvia R. Araneo 《Plant biosystems》2020,154(3):316-325
AbstractSeveral aroma hops (Humulus lupulus L.) were recently introduced in Northern Italy as a small-scale production of excellence. In this preliminary study, the American cultivar Cascade was investigated in a combined morphological and phytochemical survey. Morphological investigation on trichome structure, density and distribution was performed by scanning electron microscopy and light microscopy. Essential oil composition, α/β-acid and polyphenol profiles over 3 years were determined by GC-MS and HPLC analyses. Two types of non-glandular (simple and cystolithic) and glandular (peltate and bulbous) trichomes were observed on leaves and female inflorescences. The peltate trichomes resulted as the main sites of terpene production and accumulation. The essential oil profiles showed myrcene, β-caryophyllene, (E)-β-farnesene and humulene epoxide II as the dominant compounds over the three collection times, although with different relative abundances. The presence of two exclusive compounds, γ-muurolene and trans-γ-cadinene, characterized the investigated cv. Cascade, potentially enhancing herbal, woody and spicy aroma traits of this cultivation in Northern Italy. The bitter acid composition showed quantitative values consistent with literature data only for the second and third monitoring year. Qualitative differences in polyphenol content were also recorded, for the presence of quercetin-3-O-malonylglucoside and kaempferol-3-O-rutinoside, which may characterize this peculiar Italian cultivation. 相似文献
17.
《Saudi Journal of Biological Sciences》2020,27(11):3161-3168
Despite widespread and its local available as a naturalized hedge and shade plant, the potential of Trichilia emetica was not utilized in soap making by the majority of local community in various parts of Dodoma, Tanzania. This study aimed to assess the quantity (yields) and quality (Acid Values (AVs), %Free Fatty Acids (%FFAs) and Saponification Values (SVs) of seed oil from water plant (T. emetica), suitable for soap making application. Solvent extraction method was used during oil extraction, where by 50gm of preheated and powdered seed materials were immersed in 250 ml of n-hexane in 1:5 (w/v) to dissolve the oil contained in the seed cake. The oil was collected by vaporizing solvent out through Rotary evaporation at 60 °C. Also standard titration methods were used to obtain SVs, AVs and %FFAs of the extracted oil. Results showed that T. emetica seeds contained higher quantity of oil (48.4%−50.2%) than many reported commercial plant seed oils. Also, the study found higher AV (7.4 mgKOH/g−7.8 mgKOH/g), %FFA (3.7% to 3.9%) and SVs (189.5 mgKOH/g − 191.4 mgKOH/g) than the maximum acceptable limits of 0.50 mg KOH/g, 0.020% and 175 mgKOH/g − 187 mgKOH/g prescribed by ASTM standards (2002). The obtained results showed that, T. emetica seeds yielded high oil quantity with low qualities due to higher levels of acidity. But high SVs guarantees the possibility of using T. emetica seed oil in soap making. However, the oil requires purification in order to bring levels of acidity to acceptable standards and guarantee its normal use in soap making. 相似文献
18.
C. Lamberti S. Nebbia R. Balestrini E. Marengo M. Manfredi V. Pavese S. Cirrincione M. G. Giuffrida L. Cavallarin A. Acquadro S. Abb 《Plant biology (Stuttgart, Germany)》2020,22(3):404-409
- Caleosins are involved in several cellular and biological processes that are closely associated with the synthesis, degradation and stability of oil bodies (OB).
- Because of the importance and the multiple roles of these OB‐associated proteins, in silico identification of sequences corresponding to putative caleosins in the hazelnut genome has been performed, and the association with seed OB was verified using a proteomic approach.
- Five full‐length sequences (CavCLO‐H1, CavCLO‐H2, CavCLO‐H3, CavCLO‐L1, CavCLO‐L2), belonging to the two groups of caleosins (H and L), have been identified in the hazelnut genome. The number of identified caleosins is in agreement with that previously observed in other plant species, confirming that caleosins comprise small gene families in plants.
- A proteomic approach allowed us to verify only the presence of CavCLO‐H1 in hazelnut OB, suggesting that several members inside this family could have different roles during plant growth and development. In silico analysis also suggests that CavCLO‐H1 may act as a peroxygenase.
19.
20.
Thirty components were identified in Lavandula latifolia essential oil (spike oil). One of the compounds, espliegol (δ-terpineol), is a new natural product. 相似文献