全文获取类型
收费全文 | 16377篇 |
免费 | 2830篇 |
国内免费 | 2067篇 |
专业分类
化学 | 12370篇 |
晶体学 | 173篇 |
力学 | 962篇 |
综合类 | 110篇 |
数学 | 2107篇 |
物理学 | 5552篇 |
出版年
2024年 | 26篇 |
2023年 | 296篇 |
2022年 | 313篇 |
2021年 | 540篇 |
2020年 | 645篇 |
2019年 | 652篇 |
2018年 | 559篇 |
2017年 | 477篇 |
2016年 | 787篇 |
2015年 | 846篇 |
2014年 | 946篇 |
2013年 | 1177篇 |
2012年 | 1473篇 |
2011年 | 1509篇 |
2010年 | 1121篇 |
2009年 | 1026篇 |
2008年 | 1138篇 |
2007年 | 954篇 |
2006年 | 860篇 |
2005年 | 750篇 |
2004年 | 633篇 |
2003年 | 550篇 |
2002年 | 636篇 |
2001年 | 551篇 |
2000年 | 390篇 |
1999年 | 353篇 |
1998年 | 292篇 |
1997年 | 222篇 |
1996年 | 231篇 |
1995年 | 207篇 |
1994年 | 154篇 |
1993年 | 128篇 |
1992年 | 120篇 |
1991年 | 110篇 |
1990年 | 107篇 |
1989年 | 80篇 |
1988年 | 55篇 |
1987年 | 45篇 |
1986年 | 34篇 |
1985年 | 26篇 |
1984年 | 29篇 |
1983年 | 27篇 |
1982年 | 19篇 |
1981年 | 22篇 |
1980年 | 14篇 |
1979年 | 27篇 |
1978年 | 19篇 |
1977年 | 15篇 |
1975年 | 15篇 |
1973年 | 15篇 |
排序方式: 共有10000条查询结果,搜索用时 781 毫秒
1.
Zhihong Zhao Bin Wang Rui Tan Wenjing Liu Minghui Zhang 《Magnetic resonance in chemistry : MRC》2022,60(4):427-433
In this study, the transverse relaxation time (T2) of activated carbon (AC) in different relative environment humidity was detected firstly by low-field nuclear magnetic resonance (LFNMR). The pore size (diameter) of AC distributions was calculated by the relationship between T2 and surface relaxation rate (ρ), where ρ was obtained by the detection of nine porous materials with known pore size. The results showed that the pore size distributions of AC calculated by ρ < 0.19 nm/ms were in good agreement with that obtained by nitrogen adsorption method and proved that LFNMR as a new detection method was feasible for characterizing AC pore size distribution. 相似文献
2.
Lin Yu Wu Yeyu Tan Xuecai Wu Jiawen Huang Kejing Mi Yan Ou Panpan Wei Fucun 《Journal of Solid State Electrochemistry》2022,26(4):959-971
Journal of Solid State Electrochemistry - An ultrasensitive “signal-off–on” electrochemiluminescence (ECL) biosensor is constructed based on f1-TiO2/g-C3N4/PDA for thrombin... 相似文献
3.
Tian Xiu-Zhi Yang Rui Ma Jia-Jia Ni Yong-Hao Deng Hai-Bo Dai Lei Tan Jiao-Jun Zhang Mei-Yun Jiang Xue 《高分子科学》2022,40(7):789-798
Chinese Journal of Polymer Science - Antistatic and strength properties are of vital importance for polyurethane rubber used in moving parts of many industrial instruments. Herein, polyurethane was... 相似文献
4.
Let p ∈ [1, ∞), q ∈ [1, ∞), α∈ R, and s be a non-negative integer. Inspired by the space JNp introduced by John and Nirenberg(1961) and the space B introduced by Bourgain et al.(2015), we introduce a special John-Nirenberg-Campanato space JNcon(p,q,s) over Rn or a given cube of R;with finite side length via congruent subcubes, which are of some amalgam features. The limit space of such spaces as p →∞ is just the Campanato space which coincides with the space BMO(the space of functions with bounded mean oscillations)when α = 0. Moreover, a vanishing subspace of this new space is introduced, and its equivalent characterization is established as well, which is a counterpart of the known characterization for the classical space VMO(the space of functions with vanishing mean oscillations) over Rn or a given cube of Rn with finite side length.Furthermore, some VMO-H1-BMO-type results for this new space are also obtained, which are based on the aforementioned vanishing subspaces and the Hardy-type space defined via congruent cubes in this article. The geometrical properties of both the Euclidean space via its dyadic system and congruent cubes play a key role in the proofs of all these results. 相似文献
5.
Zeng Qing-Wei Wen Zhuo-Yu Fu Jun-Feng Zhou Nan-Run 《International Journal of Theoretical Physics》2021,60(9):3306-3333
International Journal of Theoretical Physics - A new quantum watermark algorithm is presented by combining maximum pixel difference partitioning with the least significant bit substitution... 相似文献
6.
Li Quanxin Li Zheng He Cheng Sun Huilin Tan Shengheng Zhang Hua 《Journal of Radioanalytical and Nuclear Chemistry》2022,331(5):2105-2115
Journal of Radioanalytical and Nuclear Chemistry - The simplified 8-oxide system (SiO2-B2O3-Na2O-Al2O3-CaO-TiO2-MoO3-La2O3) has been prepared under two types of cooling methods, and analyzed with... 相似文献
7.
We experimentally analyze the heat capacity and thermal expansion of reference solids in a wide temperature range from several Kelvin to melting temperature,and establish a universal double-linear relation between the experimental heat capacity Cp and thermal expansion β,which is different from the previous models.The universal behavior between heat capacity and thermal expansion is important to predict the thermodynamic parameters at constant pressure,and is helpful for understanding the nature of thermal properties in solids. 相似文献
8.
为了寻求新型蚜虫控制剂,以蚜虫报警信息素(E)-β-farnesene(EBF)为先导,引入不同类型的杂环取代EBF结构中不稳定的共轭双键,设计合成了一系列不同杂环取代的EBF类似物.所有化合物结构均通过1H NMR、13C NMR、IR及HRMS确证.对化合物进行了生物活性测试及初步构效关系分析.结果表明,所有化合物均对桃蚜和大豆蚜表现出一定的生物活性,部分化合物的杀虫活性优于先导EBF,酯基的引入则对驱避活性有利. 相似文献
9.
Jie Lu Ju-Kang Wu Yao Jiang Dr. Peng Tan Lin Zhang Yu Lei Prof. Xiao-Qin Liu Prof. Lin-Bing Sun 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(16):6490-6496
Hierarchically porous metal–organic frameworks (HP-MOFs) are promising in various applications. Most reported HP-MOFs are prepared based on the generation of mesopores in microporous frameworks, and the formed mesopores are connected by microporous channels, limiting the accessibility of mesopores for bulky molecules. A hierarchical structure is formed by constructing microporous MOFs in uninterrupted mesoporous tunnels. Using the confined space in as-prepared mesoporous silica, highly dispersed metal precursors for MOFs are coated on the internal surface of mesoporous tunnels. Ligand vapor-induced crystallization is employed to enable quantitative formation of MOFs in situ, in which sublimated ligands diffuse into mesoporous tunnels and react with metal precursors. The obtained hierarchically porous composites exhibit record-high adsorption capacity for the bulky molecule trypsin. The thermal and storage stability of trypsin is improved upon immobilization on the composites. 相似文献
10.