全文获取类型
收费全文 | 6721篇 |
免费 | 211篇 |
国内免费 | 3篇 |
专业分类
化学 | 4295篇 |
晶体学 | 34篇 |
力学 | 224篇 |
数学 | 881篇 |
物理学 | 1501篇 |
出版年
2023年 | 39篇 |
2022年 | 36篇 |
2021年 | 56篇 |
2020年 | 107篇 |
2019年 | 111篇 |
2018年 | 117篇 |
2017年 | 75篇 |
2016年 | 157篇 |
2015年 | 195篇 |
2014年 | 171篇 |
2013年 | 364篇 |
2012年 | 416篇 |
2011年 | 426篇 |
2010年 | 273篇 |
2009年 | 186篇 |
2008年 | 417篇 |
2007年 | 375篇 |
2006年 | 355篇 |
2005年 | 323篇 |
2004年 | 298篇 |
2003年 | 273篇 |
2002年 | 212篇 |
2001年 | 131篇 |
2000年 | 139篇 |
1999年 | 63篇 |
1998年 | 95篇 |
1997年 | 65篇 |
1996年 | 95篇 |
1995年 | 48篇 |
1994年 | 59篇 |
1993年 | 63篇 |
1992年 | 61篇 |
1991年 | 34篇 |
1990年 | 42篇 |
1989年 | 33篇 |
1988年 | 48篇 |
1986年 | 33篇 |
1985年 | 57篇 |
1984年 | 66篇 |
1983年 | 39篇 |
1982年 | 41篇 |
1981年 | 57篇 |
1980年 | 50篇 |
1979年 | 41篇 |
1978年 | 50篇 |
1977年 | 47篇 |
1976年 | 62篇 |
1975年 | 38篇 |
1974年 | 28篇 |
1973年 | 32篇 |
排序方式: 共有6935条查询结果,搜索用时 31 毫秒
1.
Arfè Andrea Peluso Stefano Muliere Pietro 《Statistical Inference for Stochastic Processes》2021,24(1):1-15
The literature on Bayesian methods for the analysis of discrete-time semi-Markov processes is sparse. In this paper, we introduce the semi-Markov beta-Stacy process, a stochastic process useful for the Bayesian non-parametric analysis of semi-Markov processes. The semi-Markov beta-Stacy process is conjugate with respect to data generated by a semi-Markov process, a property which makes it easy to obtain probabilistic forecasts. Its predictive distributions are characterized by a reinforced random walk on a system of urns.
相似文献2.
A CE instrument that can be assembled from commercially available components with minimal construction effort is described. Except for the electronic control circuitry no specially made parts are required. It is based on a flexible design of microfluidic, electropneumatic, and electronic sections and different configurations can easily be implemented. Automated injection into the capillary is performed hydrodynamically by the application of a pressure for a controlled length of time. The performance of the device was tested with a contactless conductivity detector by separating different metal ions. In addition, nine metal cations related to the quality of honey were separated in 2.3 min and four honey samples were analysed quantitatively to demonstrate the applicability of the method. 相似文献
3.
Elastomers are materials showing exceptional elasticity and are used for numerous applications. However, their low stiffness as well as their insulating behavior can be limiting so the incorporation of graphene-based materials can help and improve drastically their properties. With high Young's modulus, high electrical and thermal conductivities, graphene and graphene-like fillers seem ideal fillers to effectively tune elastomers properties. With low graphene-like loadings, most elasticity properties of elastomers could be preserved while increasing or adding new properties to the composites to enable new applications. Herein, we focus on the effects of “graphene” incorporation into elastomers and we will highlight the key parameters to effectively monitor the changes. 相似文献
4.
5.
6.
Raoul Walther Anna K. Winther Anne Sofie Fruergaard Wouter vandenAkker Lise Srensen Signe Maria Nielsen Morten T. JarlstadOlesen Yitao Dai Henrik S. Jeppesen Paolo Lamagni Aleksandr Savateev Sren Lykke Pedersen Camilla Kaas Frich Ccile Vigier‐Carrire Nina Lock Mandeep Singh Vipul Bansal Rikke L. Meyer Alexander N. Zelikin 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(1):284-288
Nanozymes, nanoparticles that mimic the natural activity of enzymes, are intriguing academically and are important in the context of the Origin of Life. However, current nanozymes offer mimicry of a narrow range of mammalian enzymes, near‐exclusively performing redox reactions. We present an unexpected discovery of non‐proteinaceous enzymes based on metals, metal oxides, 1D/2D‐materials, and non‐metallic nanomaterials. The specific novelty of these findings lies in the identification of nanozymes with apparent mimicry of diverse mammalian enzymes, including unique pan‐glycosidases. Further novelty lies in the identification of the substrate scope for the lead candidates, specifically in the context of bioconversion of glucuronides, that is, human metabolites and privileged prodrugs in the field of enzyme‐prodrug therapies. Lastly, nanozymes are employed for conversion of glucuronide prodrugs into marketed anti‐inflammatory and antibacterial agents, as well as “nanozyme prodrug therapy” to mediate antibacterial measures. 相似文献
7.
Harech Mohamed Amine Dabbebi Rawia Abouliatim Younes Elhafiane Youssef Smith Agnès Mesnaoui Mohamed Niboue Lahbib Baklouti Samir 《Journal of Thermal Analysis and Calorimetry》2022,147(10):5677-5686
Journal of Thermal Analysis and Calorimetry - The aim of the present work is to characterize the phosphate sludge from two different countries: Morocco and Tunisia, and to study the difference... 相似文献
8.
Irena Zupanič Pajnič Carlo Previderè Tomaž Zupanc Martina Zanon Paolo Fattorini 《Electrophoresis》2022,43(13-14):1521-1530
The recent introduction of polymerase chain reaction (PCR)-massively parallel sequencing (MPS) technologies in forensics has changed the approach to allelic short tandem repeat (STR) typing because sequencing cloned PCR fragments enables alleles with identical molecular weights to be distinguished based on their nucleotide sequences. Therefore, because PCR fidelity mainly depends on template integrity, new technical issues could arise in the interpretation of the results obtained from the degraded samples. In this work, a set of DNA samples degraded in vitro was used to investigate whether PCR-MPS could generate “isometric drop-ins” (IDIs; i.e., molecular products having the same length as the original allele but with a different nucleotide sequence within the repeated units). The Precision ID GlobalFiler NGS STR panel kit was used to analyze 0.5 and 1 ng of mock samples in duplicate tests (for a total of 16 PCR-MPS analyses). As expected, several well-known PCR artifacts (such as allelic dropout, stutters above the threshold) were scored; 95 IDIs with an average occurrence of 5.9 IDIs per test (min: 1, max: 11) were scored as well. In total, IDIs represented one of the most frequent artifacts. The coverage of these IDIs reached up to 981 reads (median: 239 reads), and the ratios with the coverage of the original allele ranged from 0.069 to 7.285 (median: 0.221). In addition, approximately 5.2% of the IDIs showed coverage higher than that of the original allele. Molecular analysis of these artifacts showed that they were generated in 96.8% of cases through a single nucleotide change event, with the C > T transition being the most frequent (85.7%). Thus, in a forensic evaluation of evidence, IDIs may represent an actual issue, particularly when DNA mixtures need to be interpreted because they could mislead the operator regarding the number of contributors. Overall, the molecular features of the IDIs described in this work, as well as the performance of duplicate tests, may be useful tools for managing this new class of artifacts otherwise not detected by capillary electrophoresis technology. 相似文献
9.
10.