全文获取类型
收费全文 | 5006篇 |
免费 | 547篇 |
国内免费 | 661篇 |
专业分类
6214篇 |
出版年
2024年 | 14篇 |
2023年 | 64篇 |
2022年 | 186篇 |
2021年 | 315篇 |
2020年 | 253篇 |
2019年 | 304篇 |
2018年 | 227篇 |
2017年 | 195篇 |
2016年 | 253篇 |
2015年 | 374篇 |
2014年 | 375篇 |
2013年 | 418篇 |
2012年 | 449篇 |
2011年 | 414篇 |
2010年 | 248篇 |
2009年 | 238篇 |
2008年 | 256篇 |
2007年 | 187篇 |
2006年 | 199篇 |
2005年 | 159篇 |
2004年 | 167篇 |
2003年 | 149篇 |
2002年 | 195篇 |
2001年 | 130篇 |
2000年 | 87篇 |
1999年 | 70篇 |
1998年 | 41篇 |
1997年 | 32篇 |
1996年 | 36篇 |
1995年 | 23篇 |
1994年 | 25篇 |
1993年 | 20篇 |
1992年 | 23篇 |
1991年 | 13篇 |
1990年 | 14篇 |
1989年 | 13篇 |
1988年 | 11篇 |
1987年 | 5篇 |
1986年 | 9篇 |
1985年 | 5篇 |
1984年 | 2篇 |
1983年 | 5篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1980年 | 3篇 |
1979年 | 2篇 |
1974年 | 1篇 |
1970年 | 1篇 |
1969年 | 1篇 |
排序方式: 共有6214条查询结果,搜索用时 15 毫秒
21.
Diversity of endophytic bacteria within nodules of the Sphaerophysa salsula in different regions of Loess Plateau in China 总被引:1,自引:0,他引:1
Deng ZS Zhao LF Kong ZY Yang WQ Lindström K Wang ET Wei GH 《FEMS microbiology ecology》2011,76(3):463-475
A total of 115 endophytic bacteria were isolated from root nodules of the wild legume Sphaerophysa salsula grown in two ecological regions of Loess Plateau in China. The genetic diversity and phylogeny of the strains were revealed by restriction fragment length polymorphism and sequencing of 16S rRNA gene and enterobacterial repetitive intergenic consensus-PCR. Their symbiotic capacity was checked by nodulation tests and analysis of nifH gene sequence. This is the first systematic study on endophytic bacteria associated with S. salsula root nodules. Fifty of the strains found were symbiotic bacteria belonging to eight putative species in the genera Mesorhizobium, Rhizobium and Sinorhizobium, harboring similar nifH genes; Mesorhizobium gobiense was the main group and 65 strains were nonsymbiotic bacteria related to 17 species in the genera Paracoccus, Sphingomonas, Inquilinus, Pseudomonas, Serratia, Mycobacterium, Nocardia, Streptomyces, Paenibacillus, Brevibacillus, Staphylococcus, Lysinibacillus and Bacillus, which were universally coexistent with symbiotic bacteria in the nodules. Differing from other similar studies, the present study is the first time that symbiotic and nonsymbiotic bacteria have been simultaneously isolated from the same root nodules, offering the possibility to accurately reveal the correlation between these two kinds of bacteria. These results provide valuable information about the interactions among the symbiotic bacteria, nonsymbiotic bacteria and their habitats. 相似文献
22.
Wei Zhou Jianyi Zhu Songdong Shen Shan Lu Jinfeng Wang Jianrong Xu Pu Xu 《Journal of applied phycology》2008,20(5):991-999
Nuclear divisions of carpospores, conchocelis and conchospores of Porphyra yezoensis, P. haitanensis, P. katadai var. hemiphylla and P. oligospermatangia from China were investigated. The observations showed diploid chromosome numbers of 2n = 6 for P. yezoensis and P. oligospermatangia, and 2n = 10 for P. haitanensis and P. katadai var. hemiphylla. For all four species, somatic pairing of chromosome sets was observed in late prophase. Sister chromosomes separated at
anaphase as mitosis took place in carpospores, conchocelis filamentous cells, conchosporangial branch cells and sporangial
cells (conchospore formation). Chromosome configurations of tetrad and ring-shaped in conchospore germination were observed,
demonstrating the occurrence of meiosis. The characteristics of diploid nuclear division in 2n = 6 species are the same as
those of 2n = 10 species. The influence of somatic pairing on nuclear division of diploid cells in Porphyra was discussed. 相似文献
23.
植物种质离体保存技术研究进展 总被引:9,自引:1,他引:9
本文综述了国内外植物种质离体保存技术最新研究进展。科学家们已发展了一系列行之有效的离体保存技术体系,进一步建立长期、安全、适用的离体保存技术体系及探索保存过程中遗传变异情况是今后的重要研究方向 相似文献
24.
25.
Twenty-one Rhizoctonia-like fungal strains were isolated from the roots of four terrestrial orchid species from various locations in Hong Kong. The cultural morphology, nuclear number of the hyphal cell, pore ultrastructure, and RAPD and CAPS analyses of rDNA fragments revealed that most of these isolates were associated with the genera Ceratorhiza and Epulorhiza. RAPD analysis showed the presence of genetic diversity between the isolates from different hosts and locations. The compatibility between a selection of these Ceratorhiza and Epulorhiza isolates and 14 orchid species was determined using a symbiotic germination method. The germination and development of three orchid species, Arundina chinensis, Spathoglottis pubescens, and Spiranthes hongkongensis, were strongly stimulated by the Epulorhiza isolates. Habenaria dentata was found to form symbionts successfully with a Ceratorhiza isolate. 相似文献
26.
27.
目的通过研究辛伐他汀对动脉粥样硬化大鼠血管壁中细胞凋亡相关基因Fas及FasL蛋白表达产物的影响,探讨其在预防动脉粥样硬化发生中的可能机制。方法复制动脉粥样硬化大鼠模型,以辛伐他汀干预,取胸主动脉,观察其斑块变化,采用免疫组化Elivision法测定动脉粥样硬化血管壁中Fas、FasL蛋白表达。结果Fas蛋白表达在实验组明显高于对照组及干预组(P<0.01,P<0.05),实验组FasL蛋白表达也明显高于对照组及干预组(P<0.05)。结论Fas及FasL基因通过促进细胞凋亡作用而诱发动脉粥样硬化过程,辛伐他汀可通过调节细胞凋亡过程发挥抗动脉粥样硬化作用。 相似文献
28.
目的 探究阴道微生态与高危型人乳头瘤病毒(HR HPV)感染以及宫颈病变之间的相关性,为后续研究提供参考。 方法 选择2018年1月至2019年6月就诊于石河子大学医学院第一附属医院妇科门诊,同时行爱必维(细菌性阴道病五项联合测定试剂盒)检测、HR HPV检测及宫颈组织病理检查的343名妇女作为研究对象,分析相关检测数据并探究阴道微生态与HR HPV感染以及宫颈病变的相关性。 结果 过氧化氢阳性、唾液酸苷酶阳性、白细胞酯酶阳性、乳杆菌数量减少及阴道清洁度3~4度的妇女感染HR HPV及发生宫颈病变的可能性显著大于过氧化氢阴性、唾液酸苷酶阴性、白细胞酯酶阴性、乳杆菌数量较多及阴道清洁度1~2度的妇女,差异均有统计学意义(均P结论 阴道微生态失衡与HR HPV感染以及宫颈病变有一定关联,纠正阴道微生态失衡可一定程度上预防HR HPV感染及宫颈病变。 相似文献
29.
Chiakang Ho Ya Gao Danning Zheng Yanjun Liu Shengzhou Shan Bin Fang Yixuan Zhao Dingzhong Song Yifan Zhang Qingfeng Li 《Journal of cellular and molecular medicine》2019,23(8):5108-5118
Obesity and its associated metabolic disorders such as diabetes, hepatic steatosis and chronic heart diseases are affecting billions of individuals. However there is no satisfactory drug to treat such diseases. In this study, we found that alisol A, a major active triterpene isolated from the Chinese traditional medicine Rhizoma Alismatis, could significantly attenuate high‐fat‐diet‐induced obesity. Our biochemical detection demonstrated that alisol A remarkably decreased lipid levels, alleviated glucose metabolism disorders and insulin resistance in high‐fat‐diet‐induced obese mice. We also found that alisol A reduced hepatic steatosis and improved liver function in the obese mice model.In addition, protein expression investigation revealed that alisol A had an active effect on AMPK/ACC/SREBP‐1c pathway. As suggested by the molecular docking study, such bioactivity of alisol A may result from its selective binding to the catalytic region of AMPK.Therefore, we believe that Alisol A could serve as a promising agent for treatment of obesity and its related metabolic diseases. 相似文献
30.
Lin Xu Yong Zhang Zheng Shan Deng Liang Zhao Xiu Li Wei Ge Hong Wei 《Antonie van Leeuwenhoek》2013,103(3):559-565
During a study of the diversity and phylogeny of rhizobia isolated from root nodules of Oxytropis ochrocephala grown in the northwest of China, four strains were classified in the genus Rhizobium on the basis of their 16S rRNA gene sequences. These strains have identical 16S rRNA gene sequences, which showed a mean similarity of 94.4 % with the most closely related species, Rhizobium oryzae. Analysis of recA and glnA sequences showed that these strains have less than 88.1 and 88.7 % similarity with the defined species of Rhizobium, respectively. The genetic diversity revealed by ERIC-PCR fingerprinting indicated that the isolates correspond to different strains. Strain CCNWQLS01T contains Q-10 as the predominant ubiquinone. The major fatty acids were identified as feature 8 (C18: 1ω7c and/or C18: 1ω6c; 67.2 %). Therefore, a novel species Rhizobium qilianshanense sp. nov. is proposed, and CCNWQLS01T (= ACCC 05747T = JCM 18337T) is designated as the type strain. 相似文献