全文获取类型
收费全文 | 19118篇 |
免费 | 1420篇 |
国内免费 | 1254篇 |
出版年
2024年 | 31篇 |
2023年 | 237篇 |
2022年 | 453篇 |
2021年 | 936篇 |
2020年 | 574篇 |
2019年 | 823篇 |
2018年 | 816篇 |
2017年 | 574篇 |
2016年 | 844篇 |
2015年 | 1124篇 |
2014年 | 1369篇 |
2013年 | 1457篇 |
2012年 | 1713篇 |
2011年 | 1545篇 |
2010年 | 983篇 |
2009年 | 947篇 |
2008年 | 1057篇 |
2007年 | 989篇 |
2006年 | 812篇 |
2005年 | 701篇 |
2004年 | 536篇 |
2003年 | 527篇 |
2002年 | 441篇 |
2001年 | 343篇 |
2000年 | 299篇 |
1999年 | 291篇 |
1998年 | 166篇 |
1997年 | 159篇 |
1996年 | 159篇 |
1995年 | 119篇 |
1994年 | 87篇 |
1993年 | 71篇 |
1992年 | 112篇 |
1991年 | 82篇 |
1990年 | 68篇 |
1989年 | 54篇 |
1988年 | 45篇 |
1987年 | 43篇 |
1986年 | 38篇 |
1985年 | 51篇 |
1984年 | 8篇 |
1983年 | 17篇 |
1982年 | 9篇 |
1981年 | 11篇 |
1980年 | 7篇 |
1979年 | 7篇 |
1978年 | 6篇 |
1977年 | 5篇 |
1974年 | 5篇 |
1969年 | 11篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
941.
N-Glycan structure annotation of glycopeptides using a linearized glycan structure database (GlyDB) 总被引:1,自引:0,他引:1
While glycoproteins are abundant in nature, and changes in glycosylation occur in cancer and other diseases, glycoprotein characterization remains a challenge due to the structural complexity of the biopolymers. This paper presents a general strategy, termed GlyDB, for glycan structure annotation of N-linked glycopeptides from tandem mass spectra in the LC-MS analysis of proteolytic digests of glycoproteins. The GlyDB approach takes advantage of low-energy collision-induced dissociation of N-linked glycopeptides that preferentially cleaves the glycosidic bonds while the peptide backbone remains intact. A theoretical glycan structure database derived from biosynthetic rules for N-linked glycans was constructed employing a novel representation of branched glycan structures consisting of multiple linear sequences. The commonly used peptide identification program, Sequest, could then be utilized to assign experimental tandem mass spectra to individual glycoforms. Analysis of synthetic glycopeptides and well-characterized glycoproteins demonstrate that the GlyDB approach can be a useful tool for annotation of glycan structures and for selection of a limited number of potential glycan structure candidates for targeted validation. 相似文献
942.
Gu X Lin L Zheng X Zhang T Song X Wang J Li X Li P Chen G Wu J Wu L Liu J 《Birth defects research. Part A, Clinical and molecular teratology》2007,79(10):702-707
BACKGROUND: Shanxi Province has historically reported a high prevalence of NTDs. In order to establish baseline rates for NTDs and discuss the risk factors associated with sociodemographic, maternal characteristics, and geographic factors, we performed the present study using an approach combining population and hospital-based methodologies. METHODS: We used chi(2) and Fisher's exact tests to evaluate variation in the prevalence by selected covariates and computed crude ORs and 95% CIs. Adjusted odds ratios (AORs) were performed using logistic regression with all the covariates included in the model. RESULTS: The overall NTD prevalence during the 3 year study period was 199.38 per 10,000 births, with a higher NTD prevalence clustered in 46 villages within this geographic area. However, no statistical significance was found between NTD prevalence and the elevation of the villages or their distance from coal plants. AORs revealed women aged 20 and above had a lower risk of NTDs compared to those younger than 20 (AOR range 0.4-0.5). A higher risk of NTDs was observed among female infants (AOR 1.50; 95% CI: 1.04-2.17), women with four or more previous births (AOR 2.80; 95% CI: 1.20-6.52), and a previous history of birth defects (AOR 3.23; 95% CI: 1.46-7.12). CONCLUSIONS: This study has documented a high prevalence of NTDs in Shanxi. Similar variations to other reports were found in the risk of NTDs by maternal demographic characteristics and a clustering of NTDs in certain villages that require further exploration. 相似文献
943.
944.
Marine Biotechnology - Large yellow croaker (Larimichthys crocea), yellow drum (Nibea albiflora), and Chinese seabass (Lateolabrax maculatus) are important economic marine fishes in China. The... 相似文献
945.
Huang Jingyu Wang Xia Wang Xiaoyan Chen Yongjuan Yang Zhiwei Xie Shuguang Li Tingting Song Shuang 《Aquatic Ecology》2022,56(3):841-857
Aquatic Ecology - Ammonia oxidation driven by ammonia-oxidizing archaea (AOA) and bacteria (AOB) plays a significant role in the nitrogen cycle, but the mechanism of this important action... 相似文献
946.
Iqbal Farheena Krzeminska-Ahmadzai Urszula Ayub Qasim Wilson Robyn Song Beng Kah Fahim Muhammad Rahman Sadequr 《Biological invasions》2022,24(3):861-878
Biological Invasions - What kind of genetic structure helps the rapid range expansion of the invasive species is fundamental to understand spread of invasion. The House crow (Corvus splendens), an... 相似文献
947.
Xiong Yaoyao Song Xiaohang Kudusi Zu Xiongbing Chen Minfeng He Wei Qi Lin 《Functional & integrative genomics》2022,22(5):937-950
Functional & Integrative Genomics - In bladder cancer patients, metastasis after surgical resection and serious adverse reactions brought by cisplatin-based systemic chemotherapy make it urgent... 相似文献
948.
Husemann Martin Dey Lara-Sophie Sadílek David Ueshima Norihiro Hawlitschek Oliver Song Hojun Weissman David B. 《Organisms Diversity & Evolution》2022,22(3):649-657
Organisms Diversity & Evolution - Orthoptera have some of the largest genomes of all insects. At the same time, the architecture of their genomes remains poorly understood. Comparative... 相似文献
949.
为了调整低山丘陵区低效林林分结构,探明马尾松(Pinus massoniana Lamb.)与乡土阔叶树种凋落叶混合分解过程中的全碳(C)释放规律。本研究以华南广泛分布的马尾松、檫木(Sassafras tzumu(Hemsl.) Hemsl)、香樟(Cinnamomum camphora(Linn) Presl)以及香椿(Toona sinensis(A. Juss.) Roem.)凋落叶为研究对象,将这4个树种凋落叶按照不同树种搭配以及混合比例组合为35个处理后进行野外分解实验,探讨C释放最佳的凋落叶树种组合以及混合比例。研究发现:4个单一树种凋落叶之间,香椿凋落叶的C释放最快,檫木和香樟凋落叶次之,马尾松凋落叶最慢。31个混合凋落叶中,C释放的非加和效应随着分解时间的延长表现出先升增强后减弱的趋势,且相对于其他季节,凋落叶在秋季的非加和效应有所减弱。一针一阔树种组合中,香樟凋落叶占比≥30%的处理:PC73和PC64的协同效应较强;一针两阔和一针三阔组合中,阔叶占比≥30%且含有香椿凋落叶的处理:PST613和712、PCT631和613、PSCT7111和6121的协同效应较强。 相似文献
950.