全文获取类型
收费全文 | 17594篇 |
免费 | 1666篇 |
国内免费 | 3003篇 |
出版年
2024年 | 82篇 |
2023年 | 323篇 |
2022年 | 738篇 |
2021年 | 1084篇 |
2020年 | 875篇 |
2019年 | 976篇 |
2018年 | 842篇 |
2017年 | 635篇 |
2016年 | 871篇 |
2015年 | 1319篇 |
2014年 | 1511篇 |
2013年 | 1570篇 |
2012年 | 1933篇 |
2011年 | 1704篇 |
2010年 | 1067篇 |
2009年 | 1010篇 |
2008年 | 1071篇 |
2007年 | 861篇 |
2006年 | 761篇 |
2005年 | 622篇 |
2004年 | 510篇 |
2003年 | 454篇 |
2002年 | 334篇 |
2001年 | 213篇 |
2000年 | 179篇 |
1999年 | 167篇 |
1998年 | 91篇 |
1997年 | 65篇 |
1996年 | 68篇 |
1995年 | 68篇 |
1994年 | 43篇 |
1993年 | 29篇 |
1992年 | 35篇 |
1991年 | 35篇 |
1990年 | 21篇 |
1989年 | 21篇 |
1988年 | 8篇 |
1987年 | 13篇 |
1986年 | 7篇 |
1985年 | 11篇 |
1984年 | 8篇 |
1983年 | 9篇 |
1982年 | 10篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1950年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 26 毫秒
61.
Genetically and phenotypically identical immune cell populations can be highly heterogenous in terms of their immune functions and protein secretion profiles. The microfluidic chip-based single-cell highly multiplexed secretome proteomics enables characterization of cellular heterogeneity of immune responses at different cellular and molecular layers. Increasing evidence has demonstrated that polyfunctional T cells that simultaneously produce 2+ proteins per cell at the single-cell level are key effector cells that contribute to the development of potent and durable cellular immunity against pathogens and cancers. The functional proteomic technology offers a wide spectrum of cellular function assessment and can uniquely define highly polyfunctional cell subsets with cytokine signatures from live individual cells. This high-dimensional single-cell analysis provides deep dissection into functional heterogeneity and helps identify predictive biomarkers and potential correlates that are crucial for immunotherapeutic product design optimization and personalized immunotherapy development to achieve better clinical outcomes. 相似文献
62.
63.
64.
65.
Jing‐Fang Guo Baosheng Wang Zhan‐Lin Liu Jian‐Feng Mao Xiao‐Ru Wang Wei Zhao 《植物分类学报:英文版》2023,61(1):143-156
Endemic species are important components of regional biodiversity and hold the key to understanding local adaptation and evolutionary processes that shape species distributions. This study investigated the biogeographic history of a relict conifer Pinus bungeana Zucc. ex Endl. confined to central China. We examined genetic diversity in P. bungeana using genotyping-by-sequencing and chloroplast and mitochondrial DNA markers. We performed spatial and temporal inference of recent genetic and demographic changes, and dissected the impacts of geography and environmental gradients on population differentiation. We then projected P. bungeana's risk of decline under future climates. We found extremely low nucleotide diversity (average π 0.0014), and strong population structure (global FST 0.234) even at regional scales, reflecting long-term isolation in small populations. The species experienced severe bottlenecks in the early Pliocene and continued to decline in the Pleistocene in the western distribution, whereas the east expanded recently. Local adaptation played a small (8%) but significant role in population diversity. Low genetic diversity in fragmented populations makes the species highly vulnerable to climate change, particularly in marginal and relict populations. We suggest that conservation efforts should focus on enhancing gene pool and population growth through assisted migration within each genetic cluster to reduce the risk of further genetic drift and extinction. 相似文献
66.
67.
68.
69.
Restoration of cytoplasmic male sterility (CMS) in sunflower was demonstrated to be controlled by polygenes by analysing 982 effective crosses among 109 self-crossed lines and 16 CMS lines. Two self-crossed lines and one CMS line with distinct genotypes were applied to creation of segregating populations for DNA bulks of the target gene Rfl. Bulked DNA was prepared in order to investigate single gene Rfl and its gene marker among polygenic characters at the same genetic background. Using 80 10-mer operon primers, 620 RAPD reactions were carried out between fertile and sterile DNA bulks. In about 800 loci, primary results showed that 8 were related to the restoration genes. Furthermore. 2 were confirmed as RAPD markers for gene Rfl by examining 9 maintenance and 7 restoration lines. This method is the improvement for bulked segregant analysis[1] with which markers of single gene of target can be identified rapidly among polygenic characters. 相似文献
70.
微生物产生的木聚糖酶的功能和应用 总被引:19,自引:0,他引:19
术聚糖是一种异质多糖,主要由木糖和阿拉伯糖组成。微生物产生的木聚糖酶来源广泛,能将木聚糖水解为木寡糖和D-木糖。该酶具有极大的应用价值,如可用于纸浆的漂白以减少环境污染,也可将造纸工业及农业废料中的木聚糖转化为D-木糖。 相似文献