全文获取类型
收费全文 | 2157篇 |
免费 | 173篇 |
国内免费 | 193篇 |
专业分类
2523篇 |
出版年
2024年 | 4篇 |
2023年 | 30篇 |
2022年 | 68篇 |
2021年 | 105篇 |
2020年 | 68篇 |
2019年 | 109篇 |
2018年 | 102篇 |
2017年 | 73篇 |
2016年 | 90篇 |
2015年 | 142篇 |
2014年 | 147篇 |
2013年 | 136篇 |
2012年 | 202篇 |
2011年 | 167篇 |
2010年 | 98篇 |
2009年 | 81篇 |
2008年 | 107篇 |
2007年 | 86篇 |
2006年 | 75篇 |
2005年 | 72篇 |
2004年 | 39篇 |
2003年 | 49篇 |
2002年 | 54篇 |
2001年 | 36篇 |
2000年 | 32篇 |
1999年 | 48篇 |
1998年 | 22篇 |
1997年 | 32篇 |
1996年 | 21篇 |
1995年 | 29篇 |
1994年 | 30篇 |
1993年 | 16篇 |
1992年 | 35篇 |
1991年 | 22篇 |
1990年 | 19篇 |
1989年 | 14篇 |
1988年 | 11篇 |
1987年 | 6篇 |
1986年 | 4篇 |
1985年 | 8篇 |
1984年 | 12篇 |
1983年 | 6篇 |
1981年 | 2篇 |
1980年 | 1篇 |
1978年 | 1篇 |
1977年 | 4篇 |
1975年 | 2篇 |
1974年 | 1篇 |
1972年 | 2篇 |
1971年 | 2篇 |
排序方式: 共有2523条查询结果,搜索用时 15 毫秒
101.
Two new species, Talaromyces heiheensis from rotten wood and T. mangshanicus isolated from soil, are illustrated and described as new to science in sections Trachyspermi and Talaromyces. The phylogenetic positions of the two new species inferred from the internal transcribed spacer, beta-tubulin, calmodulin and RNA polymerase II second largest subunit regions were carried out. Talaromyces heiheensis is phylogenetically closely related to T. albobiverticillius, T. rubrifaciens, T. solicola and T. erythromellis, and characterised by slow growth on Czapek yeast autolysate agar at 25 °C, orange conidia en masse on malt extract agar at 25 °C, biverticillate and terverticillate conidiophores, acerose phialides and subglobose to ellipsoidal, smooth-walled conidia. Talaromyces mangshanicus is related to T. kendrickii, T. qii and T. thailandensis, and characterised by slow-growing colonies with absent or sparse sporulation on CYA agar at 25 °C, conidia en masse greyish purple, purplish red soluble pigment on yeast extract agar (YES) at 25 °C, biverticillate conidiophores, ampulliform phialides and subglobose to ellipsoidal conidia with echinulate walls. They are distinguished from the known species in culture characteristics on four standard media, microscopic features and sequence data. 相似文献
102.
103.
Kan S Wang Y Sun L Jia P Qi Y Su J Liu L Yang G Liu L Wang Z Wang J Liu G Jin N Li X Ding Z 《PloS one》2012,7(2):e31979
Vaccinia Tian Tan (VTT) was attenuated by deletion of the TC7L-TK2L and TA35R genes to generate MVTT3. The mutant was generated by replacing the open reading frames by a gene encoding enhanced green fluorescent protein (EGFP) flanked by loxP sites. Viruses expressing EGFP were then screened for and purified by serial plaque formation. In a second step the marker EGFP gene was removed by transfecting cells with a plasmid encoding cre recombinase and selecting for viruses that had lost the EGFP phenotype. The MVTT3 mutant was shown to be avirulent and immunogenic. These results support the conclusion that TC7L-TK2L and TA35R deletion mutants can be used as safe viral vectors or as platform for vaccines. 相似文献
104.
Identification of QTL for growth- and grain yield-related traits in rice across nine locations of Asia 总被引:19,自引:0,他引:19
Hittalmani S Huang N Courtois B Venuprasad R Shashidhar HE Zhuang JY Zheng KL Liu GF Wang GC Sidhu JS Srivantaneeyakul S Singh VP Bagali PG Prasanna HC McLaren G Khush GS 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2003,107(4):679-690
Rice double-haploid (DH) lines of an indica and japonica cross were grown at nine different locations across four countries in Asia. Genotype-by-environment (G x E) interaction analysis for 11 growth- and grain yield-related traits in nine locations was estimated by AMMI analysis. Maximum G x E interaction was exhibited for fertility percentage number of spikelets and grain yield. Plant height was least affected by environment, and the AMMI model explained a total of 76.2% of the interaction effect. Mean environment was computed by averaging the nine environments and subsequently analyzed with other environments to map quantitative trait loci (QTL). QTL controlling the 11 traits were detected by interval analysis using mapmaker/qtl. A threshold LOD of >/=3.20 was used to identify significant QTL. A total of 126 QTL were identified for the 11 traits across nine locations. Thirty-four QTL common in more than one environment were identified on ten chromosomes. A maximum of 44 QTL were detected for panicle length, and the maximum number of common QTL were detected for days to heading detected. A single locus for plant height (RZ730-RG810) had QTL common in all ten environments, confirming AMMI results that QTL for plant height were affected the least by environment, indicating the stability of the trait. Two QTL were detected for grain yield and 19 for thousand-grain weight in all DH lines. The number of QTL per trait per location ranged from zero to four. Clustering of the QTL for different traits at the same marker intervals was observed for plant height, panicle number, panicle length and spikelet number suggesting that pleiotropism and or tight linkage of different traits could be the possible reason for the congruence of several QTL. The many QTL detected by the same marker interval across environments indicate that QTL for most traits are stable and not essentially affected by environmental factors. 相似文献
105.
106.
Zhuang Tang Wei Du XiaoLong Du YueYuan Ban JiaLing Cheng 《Journal of Plant Growth Regulation》2016,35(3):618-631
The ability to form mature adventitious roots (AR) provides a competitive advantage for clonal multiplication of elite genotypic plant species, because high economic losses occur as a result of insufficient rooting. To better understand potential mechanisms involved in AR formation, we utilized an iTRAQ-based proteomic approach on mulberry hardwood cuttings. A total of 4427 proteins were identified from the base of cuttings, of which 595 and 231 proteins showed differential accumulations in the two periods of rooting, respectively. Three differentially expressed enzyme proteins were validated by an enzyme assay and qPCR. Functional annotation analysis showed that dysregulated proteins were involved in glucose metabolism, flavonoids biosynthesis, cell wall modification, and hormone regulation, indicating potential contributions to adventitious rooting. These results provide fundamental and important information for research on the molecular mechanism of AR development in mulberry cuttings and facilitate rooting efficiency in agricultural practice. 相似文献
107.
Protective effects of intermittent hypoxic adaptation on myocardium and its mechanisms. 总被引:4,自引:0,他引:4
Intermittent hypoxic adaptation offers as many beneficial effects in protecting against myocardial injuries as chronic continuous hypoxic adaptation. However, chronic continuous hypoxic adaptation readily causes some adverse effects on the organism, which may be prevented by intermittent hypoxic adaptation. As an approach to potentiate the protective effects, intermittent hypoxic adaptation is also much easier to apply to subjects who are not living at high altitude. The mechanisms underlying the cardioprotective effects of intermittent hypoxic adaptation are less understood, although great similarities exist between chronic continuous and intermittent hypoxic adaptation. The participation of several factors, such as myocardial vascularity, coronary blood flow, and cardiomyoglobin, which comprise the oxygen uptake system is not apparent, while the more efficient energetic metabolism after intermittent hypoxic adaptation may be a mechanism for cardioprotection. The possible roles of several signaling transduction pathways, including adrenoceptors, prostaglandins, and the adenosinergic system, in the beneficial effects of intermittent hypoxia are compared to those of chronic continuous hypoxic adaptation. Antioxidant enzymes and stress proteins may also be part of the mechanisms contributing to the cardioprotection of the intermittent hypoxic adaptation. As the cardioprotective effects of intermittent hypoxic adaptation employ multifold mechanisms, their clear elucidation needs more efforts. 相似文献
108.
109.
Qing Chen Hong-Mei Wang Wen Zhuang Zhong-Guan Sun Jing Chen Yan Ge Ji-guo Qiu Jian He 《Antonie van Leeuwenhoek》2018,111(11):1977-1984
Strain ZZ-8T, a Gram-negative, aerobic, non-spore-forming, non-motile, yellow-pigmented, rod-shaped bacterium, was isolated from metolachlor-contaminated soil in China. The taxonomic position was investigated using a polyphasic approach. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain ZZ-8T is a member of the genus Flavobacterium and shows high sequence similarity to Flavobacterium humicola UCM-46T (97.2%) and Flavobacterium pedocola UCM-R36T (97.1%), and lower (<?97%) sequence similarity to other known Flavobacterium species. Chemotaxonomic analysis revealed that strain ZZ-8T possessed MK-6 as the major respiratory quinone; and iso-C15:0 (28.5%), summed feature 9 (iso-C17:1 w9c/C16:0 10-methyl, 22.9%), iso-C17:0 3-OH (17.0%), iso-C15:0 3-OH (8.9%), iso-C15:1 G (8.6%) and summed feature 3 (C16:1 w7c/C16:1 w6c, 5.7%) as the predominant fatty acids. The polar lipids of strain ZZ-8T were determined to be lipids, a glycolipid, aminolipids and phosphatidylethanolamine. Strain ZZ-8T showed low DNA–DNA relatedness with F. pedocola UCM-R36T (43.23?±?4.1%) and F. humicola UCM-46T (29.17?±?3.8%). The DNA G+C content was 43.3 mol%. Based on the phylogenetic and phenotypic characteristics, chemotaxonomic data and DNA–DNA hybridization, strain ZZ-8T is considered a novel species of the genus Flavobacterium, for which the name Flavobacterium zaozhuangense sp. nov. (type strain ZZ-8T?=?KCTC 62315 T?=?CCTCC AB 2017243T) is proposed. 相似文献