全文获取类型
收费全文 | 30464篇 |
免费 | 4728篇 |
国内免费 | 3446篇 |
专业分类
化学 | 21584篇 |
晶体学 | 333篇 |
力学 | 1708篇 |
综合类 | 285篇 |
数学 | 3300篇 |
物理学 | 11428篇 |
出版年
2024年 | 16篇 |
2023年 | 583篇 |
2022年 | 625篇 |
2021年 | 922篇 |
2020年 | 1195篇 |
2019年 | 1178篇 |
2018年 | 984篇 |
2017年 | 995篇 |
2016年 | 1396篇 |
2015年 | 1391篇 |
2014年 | 1632篇 |
2013年 | 2157篇 |
2012年 | 2640篇 |
2011年 | 2752篇 |
2010年 | 1802篇 |
2009年 | 1723篇 |
2008年 | 2046篇 |
2007年 | 1914篇 |
2006年 | 1677篇 |
2005年 | 1386篇 |
2004年 | 1058篇 |
2003年 | 888篇 |
2002年 | 801篇 |
2001年 | 655篇 |
2000年 | 646篇 |
1999年 | 643篇 |
1998年 | 566篇 |
1997年 | 547篇 |
1996年 | 595篇 |
1995年 | 500篇 |
1994年 | 475篇 |
1993年 | 364篇 |
1992年 | 329篇 |
1991年 | 291篇 |
1990年 | 228篇 |
1989年 | 168篇 |
1988年 | 152篇 |
1987年 | 125篇 |
1986年 | 119篇 |
1985年 | 117篇 |
1984年 | 73篇 |
1983年 | 63篇 |
1982年 | 49篇 |
1981年 | 34篇 |
1980年 | 38篇 |
1979年 | 23篇 |
1978年 | 12篇 |
1977年 | 12篇 |
1976年 | 11篇 |
1973年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
Nonlinear Dynamics - The hybrid neural model provides a computationally effective and biophysics-based neuron behavior model, which maintains its simplicity by incorporating the dynamics... 相似文献
12.
Numerical Algorithms - The BFGS method, which has great numerical stability, is one of the quasi-Newton line search methods. However, the global convergence of the BFGS method with a Wolfe line... 相似文献
13.
Heterostructured MoS2/GPC anode: the synergistic lithium storage performance and lithiation kinetics
Zhang Xia Dong Chaoyang Sun Yangang Liu Binyang Sun Lili Lu Yongjuan Yu Jing Wei Yajun Xu Yuandong 《Journal of Solid State Electrochemistry》2022,26(2):491-501
Journal of Solid State Electrochemistry - Grapefruit peel carbon (GPC) is prepared from waste grapefruit peel and further used as substrate for in situ construction of MoS2 arrays, forming MoS2/GPC... 相似文献
14.
Lithium (Li)-based batteries are the dominant energy source for consumer electronics, grid storage, and electrified transportation. However, the development of batteries based on graphite anodes is hindered by their limited energy density. With its ultrahigh theoretical capacity (3860 mAh∙g−1), low redox potential (−3.04 V), and satisfactorily low density (0.54 g∙cm−3), Li metal is the most promising anode for next-generation high-energy-density batteries. Unfortunately, the limited cycling life and safety issues raised by dendrite growth, unstable solid electrolyte interphase, and "dead Li" have inhibited their practical use. An effective strategy is to develop a suitable lithiophilic matrix for regulating initial Li nucleation behavior and controlling subsequent Li growth. Herein, single-atom cobalt coordinated to oxygen sites on graphene (Co-O-G SA) is demonstrated as a Li plating substrate to efficiently regulate Li metal nucleation and growth. Owing to its dense and more uniform lithiophilic sites than single-atom cobalt coordinated to nitrogen sites on graphene (Co-N-G SA), high electronic conductivity, and high specific surface area (519 m2∙g−1), Co-O-G SA could significantly reduce the local current density and promote the reversibility of Li plating and stripping. As a result, the Co-O-G SA based Li anodes exhibited a high Coulombic efficiency of 99.9% at a current density of 1 mA∙cm−2 with a capacity of 1 mAh∙cm−2, and excellent rate capability (high current density of 8 mA∙cm−2). Even at a high plating capacity of 6 mAh∙cm−2, the Co-O-G SA electrode could stably cycle for an ultralong lifespan of 1300 h. In the symmetric battery, the Co-O-G SA based Li anode (Co-O-G SA/Li) possessed a stable voltage profile of 18 mV for 780 h at 1 mA∙cm−2, and even at a high current density of 3 mA∙cm−2, its overpotential maintained a small hysteresis of approximately 24 mV for > 550 h. Density functional theory calculations showed that the surface of Co-O-G SA had a stronger interaction with Li atoms with a larger binding energy, −3.1 eV, than that of Co-N-G SA (−2.5 eV), leading to a uniform distribution of metallic Li on the Co-O-G SA surface. More importantly, when matched with a sulfur cathode, the resulting Co-O-G SA/lithium sulfur full batteries exhibited a high capacity of 1002 mAh∙g−1, improved kinetics with a small polarization of 191 mV, and an ultralow capacity decay rate of 0.036% per cycle for 1000 cycles at 0.5C (1C = 1675 mA∙g−1) with a steady Coulombic efficiency of nearly 100%. Therefore, this work provides novel insights into the coordination environment of single atoms for the chemistry of Li metal anodes for high-energy-density batteries. 相似文献
15.
In this paper we establish an asymptotic expansion near the boundary for solutions to the Dirichlet problem of elliptic equations with singularities near the boundary.This expansion formula shows the singularity profile of solutions at the boundary.We deal with both linear and nonlinear elliptic equations,including fully nonlinear elliptic equations and equations of Monge-Ampère type. 相似文献
16.
Jie Wang Cuicui Ma Qiannan Li Xing Wang Yang Yang Lingjian Yang Wei Jiang Sha Liao Shixiang Wang Pu Jia Ye Zhao Xiaohui Zheng 《Biomedical chromatography : BMC》2019,33(3)
Tanshinol borneol ester (DBZ) is a potential drug candidate composed of danshensu and borneol. It shows anti‐ischemic and anti‐atherosclerosis activity. However, little is known about its metabolism in vivo. This research aimed to elucidate the metabolic profile of DBZ through analyzing its metabolites using high‐performance liquid chromatography combined with electrospray ionization quadrupole time‐of‐flight mass spectrometry. Chromatographic separation was performed on an Agilent TC‐C18 column (150 × 4.6 mm, 5.0 μm) with gradient elution using methanol and water containing 0.2% (v/v) formic acid as the mobile phase. Metabolite identification involved analyzing the retention behaviors, changes in molecular weights and MS/MS fragment patterns of DBZ and its metabolites. As a result, 20 potential metabolites were detected and tentatively identified in rat plasma, urine and feces after administration of DBZ. DBZ could be metabolized to O‐methylated DBZ, DBZ‐O‐glucuronide, O‐methylated DBZ‐O‐glucuronide, hydroxylated DBZ and danshensu. Danshensu, a hydrolysis product of DBZ, could further be transformed into 12 metabolites. The proposed method was confirmed to be a reliable and sensitive alternative for characterizing metabolic pathways of DBZ and providing valuable information on its druggability. 相似文献
17.
18.
High pressure can effectively control the phase transition of MoTe2 in experiment, but the mechanism is still unclear. In this work, we show by first-principles calculations that the phase transition is suppressed and phase becomes more stable under high pressure, which originates from the pressure-induced change of the interlayer band occupancies near the Fermi energy. Specifically, the interlayer states of phase tend to be fully occupied under high pressure, while they keep partially occupied for the phase. The increase of the band occupancies makes the phase more favorable in energy and prevents the structure changing from to phase. Moreover, we also analyze the superconductivity under high pressure based on BCS theory by calculating the density of states and phonon spectra. Our results may shed some light on understanding the relationship between the interlayer band occupancy and crystal stability of MoTe2 under high pressures. 相似文献
19.
Ding Wenwen He Yongjia Lu Linnu Rao Meijuan Wang Fazhou 《Journal of Thermal Analysis and Calorimetry》2019,135(4):2009-2018
Journal of Thermal Analysis and Calorimetry - The present task is to investigate the influence of iron on the mineral composition and microstructure of the phase Q (C20A13M3S3, in the text below... 相似文献
20.
Antonov N. V. Gulitskiy N. M. Kostenko M. M. Lučivjanský T. 《Theoretical and Mathematical Physics》2019,200(3):1294-1312
Theoretical and Mathematical Physics - Using a quantum field theory renormalization group, we consider models of advection of a vector field and a tracer field by a compressible turbulent flow.... 相似文献