全文获取类型
收费全文 | 9232篇 |
免费 | 1344篇 |
国内免费 | 1068篇 |
专业分类
化学 | 6796篇 |
晶体学 | 99篇 |
力学 | 471篇 |
综合类 | 112篇 |
数学 | 1234篇 |
物理学 | 2932篇 |
出版年
2023年 | 166篇 |
2022年 | 172篇 |
2021年 | 268篇 |
2020年 | 349篇 |
2019年 | 333篇 |
2018年 | 262篇 |
2017年 | 277篇 |
2016年 | 450篇 |
2015年 | 408篇 |
2014年 | 558篇 |
2013年 | 720篇 |
2012年 | 860篇 |
2011年 | 869篇 |
2010年 | 617篇 |
2009年 | 543篇 |
2008年 | 619篇 |
2007年 | 524篇 |
2006年 | 458篇 |
2005年 | 377篇 |
2004年 | 355篇 |
2003年 | 308篇 |
2002年 | 309篇 |
2001年 | 261篇 |
2000年 | 159篇 |
1999年 | 199篇 |
1998年 | 140篇 |
1997年 | 110篇 |
1996年 | 130篇 |
1995年 | 105篇 |
1994年 | 100篇 |
1993年 | 93篇 |
1992年 | 81篇 |
1991年 | 82篇 |
1990年 | 48篇 |
1989年 | 55篇 |
1988年 | 33篇 |
1987年 | 33篇 |
1986年 | 33篇 |
1985年 | 31篇 |
1984年 | 10篇 |
1983年 | 6篇 |
1982年 | 8篇 |
1981年 | 8篇 |
1980年 | 7篇 |
1977年 | 5篇 |
1963年 | 7篇 |
1959年 | 12篇 |
1958年 | 11篇 |
1957年 | 15篇 |
1956年 | 10篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
61.
Meccanica - In gear pair actual alternating meshing process, the comprehensive errors of the transmission system and the thermal elastic deformation of the teeth body cause the gears in the meshing... 相似文献
62.
Ce∶LuAG晶体是一种性能优良的闪烁材料,但采用提拉法生长Ce∶LuAG时,经常出现开裂和包裹物缺陷。本文通过理论与实践相结合的方式分析了温度梯度、提拉速度、晶体旋转速度和热应变等因素对晶体产生缺陷的影响,并提出了解决办法,给出了适合生长优质Ce∶LuAG晶体的工艺参数:熔体上方温度梯度在5 ℃/mm左右,放肩角度在30°~60°,提拉速度1.0~1.5 mm/h,晶体旋转速度15~25 r/min。最后成功生长出直径30 mm、等径长50 mm质量较为完好的Ce∶LuAG单晶,晶体内核心面积小。 相似文献
63.
Ajit Kumar Singh Seulgi Ji Baghendra Singh Chittaranjan Das Heechae Choi Prashanth W. Menezes Arindam Indra 《Materials Today Chemistry》2022
Herein, we report a Mott-Schottky catalyst by entrapping cobalt nanoparticles inside the N-doped graphene shell (Co@NC). The Co@NC delivered excellent oxygen evolution activity with an overpotential of merely 248 mV at a current density of 10 mA cm–2 with promising long-term stability. The importance of Co encapsulated in NC has further been demonstrated by synthesizing Co nanoparticles without NC shell. The synergy between the hexagonal close-packed (hcp) and face-centered cubic (fcc) Co plays a major role to improve the OER activity, whereas the NC shell optimizes the electronic structure, improves the electron conductivity, and offers a large number of active sites in Co@NC. The density functional theory calculations have revealed that the hcp Co has a dominant role in the surface reaction of electrocatalytic oxygen evolution, whereas the fcc phase induces the built-in electric field at the interfaces with N-doped graphene to accelerate the H+ ion transport. 相似文献
64.
65.
Ayub Khurram Shahzad Zaman Waqas Qamar Miran Waheed Ali Meesam Abbas Zain Mushtaq Umair Shahzad Asif Yang Ji 《Research on Chemical Intermediates》2022,48(10):4227-4248
Research on Chemical Intermediates - Volatile organic compounds (VOCs) represent a very important class of pollutants that causes serious health effects. There is an urgent requirement to establish... 相似文献
66.
A novel strategy for the construction of many-electron symmetry-adapted wave function is proposed for ab initio valence bond (VB) calculations and is implemented for valence bond self-consistent filed (VBSCF) and breathing orbital valence bond (BOVB) methods with various orbital optimization algorithms. Symmetry-adapted VB functions are constructed by the projection operator of symmetry group. The many-electron symmetry-adapted wave function is expressed in terms of symmetry-adapted VB functions, and thus the VB calculations can be performed with the molecular symmetry restriction. Test results show that molecular symmetry reduces the computational cost of both the iteration numbers and CPU time. Furthermore, excited states with specific symmetry can be conveniently obtained in VB calculations by using symmetry-adapted VB functions. 相似文献
67.
利用化学沉淀法和溶胶凝胶法,通过两步法成功制备出含有尖晶石钴铁氧体和氧化铜的复合催化剂CoFe2O4/CuO,通过扫描电子显微镜(SEM)、X射线光电子能谱(XPS)和X射线衍射(XRD)对制备出的CoFe2O4/CuO进行表征,探究不同高级氧化体系对磺胺甲恶唑(SMX)去除能力,考察过氧乙酸(PAA)浓度、催化剂投加量、水体中常见干扰物质(Cl-,HCO-3,SO42-,HA)和不同自由基捕获剂对SMX去除的影响。分析结果表明CoFe2O4/CuO同时具有CoFe2O4与CuO的特征,对比单独CoFe2O4与CuO,CoFe2O4/CuO对PAA展现出极高的活化性能,在最佳反应条件下(催化剂投加量=20mg·L-1,c(PAA)=200μ... 相似文献
68.
Fu Yajing Li Ji Wang Hairui Zhang Jiahao Ma Zhijun Yi Qiong Liu Jianwen Wang Shiquan 《Journal of Solid State Electrochemistry》2023,27(9):2523-2531
Journal of Solid State Electrochemistry - FeS2/CoS and FeS2/CoS/C composites were synthesized by solvothermal method and following vapor phase vulcanization at mild temperature with binary oxide... 相似文献
69.
Dr. Ziyu Wang Dr. Ya Zhang Dr. Cheng Chen Dr. Ruixue Zhu Dr. Jiaming Jiang Prof. Tsu-Chien Weng Prof. Quanjiang Ji Prof. Yifan Huang Prof. Chong Fang Prof. Weimin Liu 《Angewandte Chemie (International ed. in English)》2023,62(5):e202212209
Large Stokes shift (LSS) red fluorescent proteins (RFPs) are highly desirable for bioimaging advances. The RFP mKeima, with coexisting cis- and trans-isomers, holds significance as an archetypal system for LSS emission due to excited-state proton transfer (ESPT), yet the mechanisms remain elusive. We implemented femtosecond stimulated Raman spectroscopy (FSRS) and various time-resolved electronic spectroscopies, aided by quantum calculations, to dissect the cis- and trans-mKeima photocycle from ESPT, isomerization, to ground-state proton transfer in solution. This work manifests the power of FSRS with global analysis to resolve Raman fingerprints of intermediate states. Importantly, the deprotonated trans-isomer governs LSS emission at 620 nm, while the deprotonated cis-isomer's 520 nm emission is weak due to an ultrafast cis-to-trans isomerization. Complementary spectroscopic techniques as a table-top toolset are thus essential to study photochemistry in physiological environments. 相似文献
70.
Chunlin Xie Shengfang Liu Zefang Yang Huimin Ji Shuhan Zhou Hao Wu Chao Hu Yougen Tang Xiaobo Ji Qi Zhang Haiyan Wang 《Angewandte Chemie (International ed. in English)》2023,62(16):e202218612
Developing a highly stable and dendrite-free zinc anode is essential to the commercial application of zinc metal batteries. However, the understanding of zinc dendrites formation mechanism is still insufficient. Herein, for the first time, we discover that the interfacial heterogeneous deposition induced by lattice defects and epitaxial growth limited by residual stress are intrinsic and critical causes for zinc dendrite formation. Therefore, an annealing reconstruction strategy was proposed to eliminate lattice defects and stresses in zinc crystals, which achieve dense epitaxial electrodeposition of zinc anode. The as-prepared annealed zinc anodes exhibit dendrite-free morphology and enhanced electrochemical cycling stability. This work first proves that lattice defects and residual stresses are also very important factors for epitaxial electrodeposition of zinc in addition to crystal orientation, which can provide a new mechanism for future researches on zinc anode modification. 相似文献