全文获取类型
收费全文 | 5274篇 |
免费 | 851篇 |
国内免费 | 625篇 |
专业分类
化学 | 3676篇 |
晶体学 | 60篇 |
力学 | 310篇 |
综合类 | 35篇 |
数学 | 585篇 |
物理学 | 2084篇 |
出版年
2024年 | 16篇 |
2023年 | 111篇 |
2022年 | 144篇 |
2021年 | 173篇 |
2020年 | 202篇 |
2019年 | 151篇 |
2018年 | 164篇 |
2017年 | 145篇 |
2016年 | 234篇 |
2015年 | 232篇 |
2014年 | 312篇 |
2013年 | 349篇 |
2012年 | 462篇 |
2011年 | 473篇 |
2010年 | 357篇 |
2009年 | 328篇 |
2008年 | 330篇 |
2007年 | 333篇 |
2006年 | 294篇 |
2005年 | 254篇 |
2004年 | 199篇 |
2003年 | 138篇 |
2002年 | 157篇 |
2001年 | 124篇 |
2000年 | 110篇 |
1999年 | 119篇 |
1998年 | 108篇 |
1997年 | 97篇 |
1996年 | 94篇 |
1995年 | 67篇 |
1994年 | 82篇 |
1993年 | 55篇 |
1992年 | 58篇 |
1991年 | 57篇 |
1990年 | 35篇 |
1989年 | 52篇 |
1988年 | 37篇 |
1987年 | 35篇 |
1986年 | 14篇 |
1985年 | 14篇 |
1984年 | 9篇 |
1983年 | 8篇 |
1982年 | 4篇 |
1981年 | 8篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1957年 | 2篇 |
排序方式: 共有6750条查询结果,搜索用时 15 毫秒
91.
In this paper,the symplectic perturbation series methodology of the non-conservative linear Hamiltonian system is presented for the structural dynamic response ... 相似文献
92.
Zhen-Lin Qiu Dandan Chen Zeying Deng Ke-Shan Chu Yuan-Zhi Tan Jun Zhu 《中国科学:化学(英文版)》2021,(6):1004-1008
Carbon nanohoop,a class of constrained molecular architecture consisting of linked arene units,has attracted considerable interest from both experimental and th... 相似文献
93.
Determination of an Unknown Time-dependent Heat Source from A Nonlocal Measurement by Finite Difference Method 总被引:1,自引:0,他引:1
In this paper, we consider an inverse time-dependent source problem of heat conduction equation.Firstly, the ill-posedness and conditional stability of this inverse source problem is analyzed. Then, a finite difference inversion method is proposed for reconstructing the time-dependent source from a nonlocal measurement. The existence and uniqueness of the finite difference inverse solutions are rigorously analyzed, and the convergence is proved. Combined with the mollification method, the propos... 相似文献
94.
95.
Yunjie Huang Yaqi Bao Tieqi Huang Chengzhi Hu Haiou Qiu Hongtao Liu 《Molecules (Basel, Switzerland)》2023,28(1)
Molybdenum carbide is considered to be one of the most competitive catalysts for hydrogen evolution reaction (HER) regarding its high catalytic activity and superior corrosion resistance. But the low electrical conductivity and poor interfacial contact with the current collector greatly inhibit its practical application capability. Herein, carbon nanotube (CNT) supported molybdenum carbide was assembled via electrostatic adsorption combined with complex bonding. The N-doped molybdenum carbide nanocrystals were uniformly anchored on the surfaces of amino CNTs, which depressed the agglomeration of nanoparticles while strengthening the migration of electrons. The optimized catalyst (250-800-2h) showed exceptional electrocatalytic performance towards HER under both acidic and alkaline conditions. Especially in 0.5 M H2SO4 solution, the 250-800-2h catalyst exhibited a low overpotential of 136 mV at a current density of 10 mA/cm2 (η10) with the Tafel slope of 49.9 mV dec−1, and the overpotential only increased 8 mV after 20,000 cycles of stability test. The active corrosive experiment revealed that more exposure to high-activity γ-Mo2N promoted the specific mass activity of Mo, thus, maintaining the catalytic durability of the catalyst. 相似文献
96.
97.
Yiwen Zhang Kunjian Liu Chengqiu Yan Yu Yin Shuangyan He Li Qiu Guofeng Li 《Molecules (Basel, Switzerland)》2022,27(24)
Colorectal cancer (CRC) is a prevalent and serious gastrointestinal malignancy with high mortality and morbidity. Chemoprevention refers to a newly emerged strategy that uses drugs with chemopreventive properties to promote antioxidation, regulate cancer cell cycle, suppress proliferation, and induce cellular apoptosis, so as to improve cancer treatment outcomes. Natural polyphenols are currently recognized as a class of chemopreventive agents that have shown remarkable anticarcinogenic properties. Numerous in vitro and in vivo studies have elucidated the anti-CRC mechanisms of natural polyphenols, such as regulation of various molecular and signaling pathways. Natural polyphenols are also reportedly capable of modulating the gut microbiota and cancer stem cells (CSCs) to suppress tumor formation and progression. Combined use of different natural polyphenols is recommended due to their low bioavailability and instability, and combination treatment can exert synergistical effects, reduce side effects, and avoid drug resistance in CRC treatment. In summary, the application of polyphenols in the chemoprevention and treatment of CRC is promising. Further clinical evaluation of their effectiveness is warranted and anticipated. 相似文献
98.
99.
100.
Xinheng He Ning Huang Yuran Qiu Jian Zhang Yaqin Liu Xiao-Lan Yin Shaoyong Lu 《Molecules (Basel, Switzerland)》2021,26(4)
Metastasis is the major cause of death in colorectal cancer and it has been proven that inhibiting an interaction between adenomatous polyposis coli (APC) and Rho guanine nucleotide exchange factor 4 (Asef) efficaciously restrain metastasis. However, current inhibitors cannot achieve a satisfying effect in vivo and need to be optimized. In the present study, we applied molecular dynamics (MD) simulations and extensive analyses to apo and holo APC systems in order to reveal the inhibitor mechanism in detail and provide insights into optimization. MD simulations suggested that apo APC takes on a broad array of conformations and inhibitors stabilize conformation selectively. Representative structures in trajectories show specific APC-ligand interactions, explaining the different binding process. The stability and dynamic properties of systems elucidate the inherent factors of the conformation selection mechanism. Binding free energy analysis quantitatively confirms key interface residues and guide optimization. This study elucidates the conformation selection mechanism in APC-Asef inhibition and provides insights into peptide-based drug design. 相似文献