全文获取类型
收费全文 | 544篇 |
免费 | 10篇 |
国内免费 | 112篇 |
专业分类
化学 | 379篇 |
力学 | 17篇 |
综合类 | 4篇 |
数学 | 201篇 |
物理学 | 65篇 |
出版年
2023年 | 16篇 |
2022年 | 5篇 |
2021年 | 13篇 |
2020年 | 12篇 |
2019年 | 8篇 |
2018年 | 6篇 |
2017年 | 15篇 |
2016年 | 19篇 |
2015年 | 17篇 |
2014年 | 19篇 |
2013年 | 50篇 |
2012年 | 35篇 |
2011年 | 33篇 |
2010年 | 39篇 |
2009年 | 28篇 |
2008年 | 34篇 |
2007年 | 37篇 |
2006年 | 31篇 |
2005年 | 36篇 |
2004年 | 26篇 |
2003年 | 28篇 |
2002年 | 17篇 |
2001年 | 17篇 |
2000年 | 10篇 |
1999年 | 19篇 |
1998年 | 7篇 |
1997年 | 6篇 |
1996年 | 13篇 |
1995年 | 16篇 |
1994年 | 10篇 |
1993年 | 3篇 |
1992年 | 4篇 |
1991年 | 8篇 |
1990年 | 4篇 |
1989年 | 3篇 |
1988年 | 6篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 3篇 |
1984年 | 1篇 |
1982年 | 3篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1978年 | 2篇 |
1975年 | 1篇 |
排序方式: 共有666条查询结果,搜索用时 0 毫秒
661.
662.
We propose a traffic model based on microscopic stochastic dynamics. We built a Markov chain equipped with an Arrhenius interaction
law. The resulting stochastic process is comprised of both spin-flip and spin-exchange dynamics which models vehicles exiting,
entering and interacting in a two-dimensional lattice environment corresponding to a multi-lane highway. The process is further
equipped with a novel look-ahead type, anisotropic interaction potential which allows drivers/vehicles to ascertain local
fluctuations and advance to new cells forward or sideways. The resulting vehicular traffic model is simulated via kinetic
Monte Carlo and examined under both, typical and extreme traffic flow scenarios. The model is shown to correctly predict both
qualitative as well as quantitative traffic observables for any highway geometry. Furthermore it also captures interesting
multi-scale phenomena in traffic flows after a simulated accident which lead to oscillatory, dissipating, traffic waves with
different periods per lane. 相似文献
663.
Yuyan Wang Dr. Assoc. Prof. Rui Shu Prof. Xinxing Zhang 《Angewandte Chemie (International ed. in English)》2023,62(23):e202303446
Despite the remarkable progress in ultrastrong mechanical laminate materials, the simultaneous achievement of toughness, stretchability and self-healing properties in biomimetic layered nanocomposites remains a great challenge due to the intrinsic limitations of their hard essences and lack of effective stress transfer at the organic-inorganic fragile boundary. Here, an ultratough nanocomposite laminate is prepared by constructing chain-sliding cross-linking at the interface between sulfonated graphene nanosheets and polyurethane layers based on the ring molecules sliding on the linear polymer chains to release stresses. Unlike traditional supramolecular bonding toughening with limited sliding spacing, our strategy enables interfacial molecular chains reversible slippage when the inorganic nanosheets bear stretching force, providing sufficient interlayer spatial distance for relative sliding to dissipate more energy. The resulting laminates exhibit strong strength (22.33 MPa), supertoughness (219.08 MJ m−3), ultrahigh stretchability (>1900 %) and self-healing ability (99.7 %), which far surpass most of reported synthetic and natural laminate materials. Moreover, the fabricated proof-of-concept electronic skin shows excellent flexibility, sensitivity and healability for human physiological signals monitoring. This strategy breaks through the challenge that traditional layered nanocomposites are intrinsically stiff and opens up the functional application of layered nanocomposites in flexible devices. 相似文献
664.
《Annals of Pure and Applied Logic》2023,174(9):103300
In this paper, we investigate the fresh function spectrum of forcing notions, where a new function on an ordinal is called fresh if all its initial segments are in the ground model. We determine the fresh function spectrum of several forcing notions and discuss the difference between fresh functions and fresh subsets. Furthermore, we consider the question which sets are realizable as the fresh function spectrum of a homogeneous forcing. We show that under GCH all sets with a certain closure property are realizable, while consistently there are sets which are not realizable. 相似文献
665.
Xiyuan Yu Dr. Wei Lin Dr. Qian Lai Juan Song Dr. Yilong Liu Dr. Rui Su Qi Niu Prof. Liu Yang Prof. Chaoyong Yang Dr. Huimin Zhang Prof. Zhi Zhu 《Angewandte Chemie (International ed. in English)》2023,62(17):e202301083
Unlike plant and microbial cells having cell walls, the outermost layer of mammalian cell is a delicate, two-layered structure of phospholipids with proteins embedded, which is susceptible to environmental changes. It is necessary to create an “armor” on cell surface to protect cell integrity. Here, we propose an A uto-assembled R esilient bioM imetic calcified OR naments (ARMOR) strategy driven by dual-aptamer-based hybridization chain reaction (HCR) and Ca2+ assisted calcification for selective cell protection. This co-recognition design enhances the selectivity and leverages robust in situ signal amplification by HCR to improve the sensitivity. The calcified shell is cogenerated by crosslinking the alginate-HCR product with Ca2+ ion. ARMOR has high efficiency for shielding cells from environmental assaults, which can be applied to circulating tumor cell (CTC) protection, isolation, and identification, maintaining the native state and intact genetic information for downstream analysis. 相似文献
666.
《Arabian Journal of Chemistry》2023,16(3):104521
The continuous development of resistance to antibiotic drugs by microorganisms causes high mortality and morbidity. Pathogens with distinct features and biochemical abilities make them destructive to human health. Therefore, early identification of the pathogen is of substantial importance for quick ailments and healthcare outcomes. Several phenotype methods are used for the identification and resistance determination but most of the conventional procedures are time-consuming, costly, and give qualitative results. Recently, great focus has been made on the utilization of advanced techniques for microbial identification. This review is focused on the research studies performed in the last five years for the identification of microorganisms particularly, bacteria using advanced spectroscopic techniques including mass spectrometry (MS), infrared (IR) spectroscopy, Raman spectroscopy (RS), and nuclear magnetic resonance (NMR) spectroscopy. Among all the techniques, MS techniques, particularly MALDI-TOF/MS have been widely utilized for microbial identification. A total of 44 bacteria i.e., 6 Staphylococcus spp., 3 Enterococcus spp., 6 Bacillus spp., 4 Streptococcus spp., 6 Salmonella spp., and one from each genus including Escherichia, Acinetobacter, Pseudomonas, Proteus, Clostridioides, Candida, Brucella, Burkholderia, Francisella, Yersinia, Moraxella, Vibrio, Shigella, Serratia, Citrobacter, and Haemophilus (spp.) were discussed in the review for their identification using the above-mentioned techniques. Among all the identified microorganisms, 21% of studies have been conducted for the identification of E. coli, 14% for S. aureus followed by 37% for other microorganisms. 相似文献