全文获取类型
收费全文 | 59378篇 |
免费 | 18758篇 |
国内免费 | 2469篇 |
专业分类
化学 | 65698篇 |
晶体学 | 230篇 |
力学 | 2617篇 |
综合类 | 197篇 |
数学 | 3439篇 |
物理学 | 8424篇 |
出版年
2024年 | 468篇 |
2023年 | 4439篇 |
2022年 | 2079篇 |
2021年 | 3152篇 |
2020年 | 5335篇 |
2019年 | 2967篇 |
2018年 | 2962篇 |
2017年 | 1164篇 |
2016年 | 6359篇 |
2015年 | 6392篇 |
2014年 | 5950篇 |
2013年 | 6445篇 |
2012年 | 4758篇 |
2011年 | 2885篇 |
2010年 | 4508篇 |
2009年 | 4395篇 |
2008年 | 2182篇 |
2007年 | 1772篇 |
2006年 | 1201篇 |
2005年 | 981篇 |
2004年 | 866篇 |
2003年 | 649篇 |
2002年 | 584篇 |
2001年 | 529篇 |
2000年 | 471篇 |
1999年 | 448篇 |
1998年 | 391篇 |
1997年 | 367篇 |
1996年 | 381篇 |
1995年 | 429篇 |
1994年 | 365篇 |
1993年 | 419篇 |
1992年 | 312篇 |
1991年 | 261篇 |
1990年 | 215篇 |
1989年 | 196篇 |
1988年 | 166篇 |
1987年 | 149篇 |
1986年 | 118篇 |
1985年 | 121篇 |
1980年 | 120篇 |
1977年 | 167篇 |
1976年 | 182篇 |
1975年 | 191篇 |
1974年 | 195篇 |
1972年 | 154篇 |
1971年 | 125篇 |
1970年 | 208篇 |
1969年 | 129篇 |
1968年 | 134篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
Prof. Dr. Bernhard Kräutler 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(67):15438-15445
The recently delineated structure- and reactivity-based concept of antivitamins B12 has begun to bear fruit by the generation, and study, of a range of such B12-dummies, either vitamin B12-derived, or transition metal analogues that also represent potential antivitamins B12 or specific B12-antimetabolites. As reviewed here, this has opened up new research avenues in organometallic B12-chemistry and bioinorganic coordination chemistry. Exploratory studies with antivitamins B12 have, furthermore, revealed some of their potential, as pharmacologically interesting compounds, for inducing B12-deficiency in a range of organisms, from hospital resistant bacteria to laboratory mice. The derived capacity of antivitamins B12 to induce functional B12-deficiency in mammalian cells and organs also suggest their valuable potential as growth inhibitors of cancerous human and animal cells. 相似文献
992.
Acta Mathematicae Applicatae Sinica, English Series - This paper evaluates the performance of the FW-test for testing part of p-regression coefficients in linear panel data model when p is... 相似文献
993.
Nonlinear Dynamics - A trans-media aerial underwater vehicle (TMAUV) could break through the single-medium limitation with the abilities to fly in the air, navigate underwater, and cross the... 相似文献
994.
Nonlinear Dynamics - Theoretical studies suggest that dispersion and repulsion are two important interactions that occur within non-polar particles. Enlightened by this, we propose a simple model... 相似文献
995.
Nonlinear Dynamics - A multilayer membrane element of absolute nodal coordinate formulation is proposed for dynamic modeling of multilayer dielectric elastomer actuators (DEAs). The coupled... 相似文献
996.
采用原位共生长化学气相沉积法,以Co3O4、MoO3、Se粉末为前驱物,710℃下在SiO2衬底上生长掺钴MoSe2纳米薄片,分析讨论氢气含量对其生长及调节机理的影响.表面形貌分析表明,氢气的引入促进了成核所需的氧硒金属化合物以及横向生长中需要的CoMoSe化合物分子的生成;AFM(Atomic Force Microscope)结果表明氢气有利于生长单层二维超薄掺钴MoSe2.随着Co3O4前驱物用量的增加,样品的拉曼和PL(Photoluminescence)谱图分别表现出红移和蓝移现象,带隙实现从1.52—1.57 eV的调制.XPS(X-ray photoelectron spectroscopy)结果分析得到Co的元素组分比为4.4%.通过SQUID-VSM(Superconducting QUantum Interference Device)和器件电学测试分析了样品的磁电特性,结果表明Co掺入后MoSe2由抗磁性变为软磁性;背栅FETs器件的阈值电压比纯MoSe2向正向偏移5 V且关态电流更低;为超薄二维材料磁电特性研究及应用拓展提供了基础探索. 相似文献
997.
Cheng-Cheng Tsai Zhi-Yao Tsai Ming-Yu Tseng Wei-Ping Hu 《International journal of quantum chemistry》2020,120(14):e26238
We have developed a new database of structures and bond energies of 59 noble-gas-containing molecules. The structures were calculated by CCSD(T)/aug-cc-pVTZ methods and the bond energies were obtained using the CCSD(T)/complete basis set method. Many wavefunction-based and density functional theory methods have been benchmarked against the 59 accurate bond energies. Our results show that the MPW1B95, B2GP-PLYP, and DSD-BLYP functionals with the aug-cc-pVTZ basis set excel in predicting the bond energies of noble-gas molecules with mean unsigned errors (MUEs) of 2.0 to 2.1 kcal/mol. When combinations of Dunning's basis sets are used, the MPW1B95, B2GP-PLYP, DSD-BLYP, and BMK functionals give significantly lower MUEs of 1.6 to 1.9 kcal/mol. Doubly hybrid methods using B2GP-PLYP and DSD-BLYP functionals and MP2 calculation also provide satisfactory accuracy with MUEs of 1.4 to 1.5 kcal/mol. If the Ng bond energies and the total atomization energies of a group of 109 main-group molecules are considered at the same time, the MPW1B95/aug-cc-pVTZ single-level method (MUE = 2.7 kcal/mol) and the B2GP-PLYP and DSD-PLYP functionals with combinations of basis sets or using the doubly hybrid method (MUEs = 1.9-2.2 kcal/mol) give the overall best result. 相似文献
998.
Yunjuan Zhang Prof. Dr. Shunai Che 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(1):50-60
The development of hierarchical macro- or mesoporous zeolites is essential in zeolite synthesis because the size of the micropores limits mass transport and their use as industrial catalysts for bulky molecules. Although major breakthroughs have been achieved, fabricating crystallographically ordered mesoporous zeolites using a templating strategy is still an unsolved challenge. This minireview highlights our recent efforts on the self-assembly of amphiphilic molecules to obtain ordered hierarchical MFI zeolites by introducing aromatic groups into the hydrophobic tail of the amphiphilic molecules. Owing to the geometric matching between the self-assembled aromatic tails and the MFI framework, a) single-crystalline mesostructured zeolite nanosheets (SCZNs), b) SCZNs with a 90° rotational intergrowth structure, c) a hierarchical MFI zeolite with a two-dimensional square P4mm mesostructure, and d) a single-crystalline mesoporous ZSM-5 with three-dimensional pores and sheetlike mesopores layered along the a-axis were successfully synthesized. 相似文献
999.
1000.