全文获取类型
收费全文 | 127034篇 |
免费 | 6010篇 |
国内免费 | 5257篇 |
出版年
2023年 | 599篇 |
2022年 | 1323篇 |
2021年 | 2205篇 |
2020年 | 1580篇 |
2019年 | 1972篇 |
2018年 | 2743篇 |
2017年 | 2509篇 |
2016年 | 4740篇 |
2015年 | 8927篇 |
2014年 | 9087篇 |
2013年 | 9040篇 |
2012年 | 8998篇 |
2011年 | 5917篇 |
2010年 | 4532篇 |
2009年 | 4207篇 |
2008年 | 3074篇 |
2007年 | 2811篇 |
2006年 | 2533篇 |
2005年 | 8247篇 |
2004年 | 6657篇 |
2003年 | 4824篇 |
2002年 | 2231篇 |
2001年 | 1742篇 |
2000年 | 897篇 |
1999年 | 2006篇 |
1998年 | 676篇 |
1992年 | 2119篇 |
1991年 | 2174篇 |
1990年 | 2214篇 |
1989年 | 2130篇 |
1988年 | 2067篇 |
1987年 | 1894篇 |
1986年 | 1706篇 |
1985年 | 1752篇 |
1984年 | 1134篇 |
1983年 | 899篇 |
1979年 | 1126篇 |
1978年 | 806篇 |
1977年 | 640篇 |
1976年 | 659篇 |
1975年 | 898篇 |
1974年 | 1032篇 |
1973年 | 1047篇 |
1972年 | 974篇 |
1971年 | 954篇 |
1970年 | 843篇 |
1969年 | 851篇 |
1968年 | 756篇 |
1967年 | 775篇 |
1966年 | 610篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
111.
RNA‐seq analysis reveals new candidate genes for drip loss in a Pietrain × Duroc × Landrace × Yorkshire population
下载免费PDF全文
![点击此处可从《Animal genetics》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Bojiang Li Kaiqing Liu Qiannan Weng Pinghua Li Wei Wei Qifa Li Jie Chen Ruihua Huang Wangjun Wu Honglin Liu 《Animal genetics》2016,47(2):192-199
Drip loss, one of the most important meat quality traits, is characterized by low heritability. To date, the genetic factors affecting the drip loss trait have not been clearly elucidated. The objective of this study was to identify critical candidate genes affecting drip loss. First, we generated a Pietrain × Duroc × Landrace × Yorkshire commercial pig population and obtained phenotypic values for the drip loss trait. Furthermore, we constructed two RNA libraries from pooled samples of longissimus dorsi muscles with the highest (H group) and lowest (L group) drip loss and identified the differentially expressed genes (DEGs) between these extreme phenotypes using RNA‐seq technology. In total, 25 883 genes were detected in the H and L group libraries, and none was specifically expressed in only one library. Comparative analysis of gene expression levels found that 150 genes were differentially expressed, of which 127 were upregulated and 23 were downregulated in the H group relative to the L group. In addition, 68 drip loss quantitative trait loci (QTL) overlapping with 63 DEGs were identified, and these QTL were distributed mainly on chromosomes 1, 2, 5 and 6. Interestingly, the triadin (TRDN) gene, which is involved in muscle contraction and fat deposition, and the myostatin (MSTN) gene, which has a role in muscle growth, were localized to more than two drip loss QTL, suggesting that both are critical candidate genes responsible for drip loss. 相似文献
112.
Anna M. Kauppi Alicia Edin Ingrid Ziegler Paula M?lling Anders Sj?stedt ?sa Gylfe Kristoffer Str?lin Anders Johansson 《PloS one》2016,11(1)
A metabolomics approach for prediction of bacteremic sepsis in patients in the emergency room (ER) was investigated. In a prospective study, whole blood samples from 65 patients with bacteremic sepsis and 49 ER controls were compared. The blood samples were analyzed using gas chromatography coupled to time-of-flight mass spectrometry. Multivariate and logistic regression modeling using metabolites identified by chromatography or using conventional laboratory parameters and clinical scores of infection were employed. A predictive model of bacteremic sepsis with 107 metabolites was developed and validated. The number of metabolites was reduced stepwise until identifying a set of 6 predictive metabolites. A 6-metabolite predictive logistic regression model showed a sensitivity of 0.91(95% CI 0.69–0.99) and a specificity 0.84 (95% CI 0.58–0.94) with an AUC of 0.93 (95% CI 0.89–1.01). Myristic acid was the single most predictive metabolite, with a sensitivity of 1.00 (95% CI 0.85–1.00) and specificity of 0.95 (95% CI 0.74–0.99), and performed better than various combinations of conventional laboratory and clinical parameters. We found that a metabolomics approach for analysis of acute blood samples was useful for identification of patients with bacteremic sepsis. Metabolomics should be further evaluated as a new tool for infection diagnostics. 相似文献
113.
114.
115.
Xinyao Zhu Srdjan Cirovic Aliah Shaheen Wei Xu 《Biomechanics and modeling in mechanobiology》2018,17(3):665-674
In this study, atomic force microscopy (AFM) is used to investigate the alterations of the poroelastic properties of hepatocellular carcinoma (SMMC-7721) cells treated with fullerenol. The SMMC-7721 cells were subject to AFM-based creep tests, and a corresponding poroelastic indentation model was used to determine the poroelastic parameters by curve fitting. Comparative analyses indicated that the both permeability and diffusion of fullerenol-treated cells increased significantly while their elastic modulus decreased by a small amount. From the change in the trend of the determined parameter, we verified the corresponding alternations of cytoskeleton (mainly filaments actin), which was reported by the previous study using confocal imaging method. Our investigation on SMMC-7721 cell reveals that the poroelastic properties could provide a better understanding how the cancer cells are affected by fullerenol or potentially other drugs which could find possible applications in drug efficacy test, cancer diagnosis and secure therapies. 相似文献
116.
117.
118.
Valeria L. Martin-Albarracin Guillermo C. Amico Daniel Simberloff Martin A. Nu?ez 《PloS one》2015,10(11)
Introduction and naturalization of non-native species is one of the most important threats to global biodiversity. Birds have been widely introduced worldwide, but their impacts on populations, communities, and ecosystems have not received as much attention as those of other groups. This work is a global synthesis of the impact of nonnative birds on native ecosystems to determine (1) what groups, impacts, and locations have been best studied; (2) which taxonomic groups and which impacts have greatest effects on ecosystems, (3) how important are bird impacts at the community and ecosystem levels, and (4) what are the known benefits of nonnative birds to natural ecosystems. We conducted an extensive literature search that yielded 148 articles covering 39 species belonging to 18 families -18% of all known naturalized species. Studies were classified according to where they were conducted: Africa, Asia, Australasia, Europe, North America, South America, Islands of the Indian, of the Pacific, and of the Atlantic Ocean. Seven types of impact on native ecosystems were evaluated: competition, disease transmission, chemical, physical, or structural impact on ecosystem, grazing/ herbivory/ browsing, hybridization, predation, and interaction with other non-native species. Hybridization and disease transmission were the most important impacts, affecting the population and community levels. Ecosystem-level impacts, such as structural and chemical impacts were detected. Seven species were found to have positive impacts aside from negative ones. We provide suggestions for future studies focused on mechanisms of impact, regions, and understudied taxonomic groups. 相似文献
119.
120.