全文获取类型
收费全文 | 30003篇 |
免费 | 4052篇 |
国内免费 | 3973篇 |
专业分类
化学 | 20709篇 |
晶体学 | 254篇 |
力学 | 1711篇 |
综合类 | 158篇 |
数学 | 3610篇 |
物理学 | 11586篇 |
出版年
2024年 | 43篇 |
2023年 | 449篇 |
2022年 | 721篇 |
2021年 | 829篇 |
2020年 | 889篇 |
2019年 | 898篇 |
2018年 | 849篇 |
2017年 | 703篇 |
2016年 | 1176篇 |
2015年 | 1059篇 |
2014年 | 1291篇 |
2013年 | 1765篇 |
2012年 | 2135篇 |
2011年 | 3434篇 |
2010年 | 2097篇 |
2009年 | 2015篇 |
2008年 | 1564篇 |
2007年 | 1368篇 |
2006年 | 1312篇 |
2005年 | 1340篇 |
2004年 | 1992篇 |
2003年 | 1254篇 |
2002年 | 1137篇 |
2001年 | 915篇 |
2000年 | 516篇 |
1999年 | 636篇 |
1998年 | 557篇 |
1997年 | 482篇 |
1996年 | 415篇 |
1995年 | 376篇 |
1994年 | 312篇 |
1993年 | 654篇 |
1992年 | 645篇 |
1991年 | 472篇 |
1990年 | 449篇 |
1989年 | 410篇 |
1988年 | 156篇 |
1987年 | 88篇 |
1986年 | 94篇 |
1985年 | 77篇 |
1984年 | 77篇 |
1983年 | 42篇 |
1982年 | 44篇 |
1981年 | 27篇 |
1980年 | 29篇 |
1979年 | 16篇 |
1977年 | 16篇 |
1976年 | 18篇 |
1975年 | 16篇 |
1973年 | 18篇 |
排序方式: 共有10000条查询结果,搜索用时 343 毫秒
1.
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
2.
Hao Lu Xiaodong Wang Hang Wang Andong Zhang Xinming Zheng Na Yu Zheng Tang Xinjun Xu Yahui Liu Ya-Nan Chen Zhishan Bo 《中国科学:化学(英文版)》2022,65(3):594-601
Three nonfused ring electron acceptors (NFREAs) TTC6,TT-C8T and TT-TC8 were purposefully designed and synthesized.The molecular geometry can be adjusted by the steric hindrance of lateral substituents.According to the DFT calculations,from TTC6 to TT-C8T and TT-TC8,planarity of the molecular backbone is gradually improved,accompanying with the enhancing of intramolecular charge transfer effect.As for TT-TC8,the two phenyl substituents are almost perpendicular to the molecular backbone,which endues the acceptor with good solubility and suppresses it to form over-aggregation.Multidirectional regular molecular orientation and closer molecular stacking are formed in TT-TC8 film.As a result,TT-TC8 based devices afford the highest PCE of 13.13%,which is much higher than that of TTC6 (4.41%) and TT-C8T (10.42%) and among the highest PCE values based on NFREAs. 相似文献
3.
4.
Nonlinear Dynamics - This paper proposes an optimal parameter design of control scheme for mechanical systems by adopting the Stackelberg game theory. The goal of the control is to drive the... 相似文献
5.
Science China Mathematics - Linear factor models are familiar tools used in many fields. Several pioneering literatures established foundational theoretical results of the quasi-maximum likelihood... 相似文献
6.
The influence of different referencing methods on the accuracy of δ13C value measurement of ethanol fuel by gas chromatography/combustion/isotope ratio mass spectrometry 下载免费PDF全文
7.
Nanocomposite hydrogel consisting of Na‐montmorillonite with enhanced mechanical properties 下载免费PDF全文
Ting Li Shuangfei Xiang Piming Ma Huiyu Bai Weifu Dong Mingqing Chen 《Journal of Polymer Science.Polymer Physics》2015,53(14):1020-1026
A new kind of nanocomposite (NC) hydrogel with Na‐montmorillonite (MMT) is presented in this article. The NC hydrogels were synthesized by free radical copolymerization of acrylamide and (3‐acrylamidopropyl) trimethylammonium chloride (ATC) in the presence of MMT and N,N′‐methylene‐bis‐acrylamide used as chemical cross‐linker. Due to the cation‐exchange reaction between MMT and ATC (cationic monomer) during the synthesis of NC hydrogels, MMT platelets were considered chemical “plane” cross‐linkers, different from “point” cross‐linkers. With increasing amount of MMT, the crosslinking degree enhanced, causing a decrease of the swelling degree at equilibrium. Investigations of mechanical properties indicated that NC hydrogels exhibited enhanced strength and toughness, which resulted from chemical interaction between exfoliated MMT platelets and polymer chains in hydrogels. Dynamic shear measurements showed that both storage modulus and loss modulus increased with increasing MMT content. The idea described here provided a new route to prepare hydrogels with high mechanical properties by using alternative natural Na‐MMT. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 1020–1026 相似文献
8.
9.
Zhen Xi 《中国科学:化学(英文版)》2015,(3):434-435
Redox-based post-translational modification of protein thiols has become an attractive strategy in cellular homeostasis and cell signaling.Due to the reductive end of the redox buffer network,the vicinal dithiol-containing proteins(VDPs)maintains an appropriate oxidation-reduction state of proteins through the reversible transformation from vicinal dithiols to disulfide,which is responsible for a variety of 相似文献
10.
Lijuan Shen Li Li Sheng Lu Xiaohan Zhang Jie Liu Junlin An Guojun Zhang Bo Wu Fei Wang 《中国颗粒学报》2015,(3):10-15
We conducted measurements of black carbon(BC) aerosol in Jiaxing,China during autumn from September 26 to November 30,2013.We investigated temporal and diurnal variations of BC,and its correlations with meteorological parameters and other major pollutants.Results showed that hourly mass concentrations of BC ranged from 0.2 to 22.0 μg/m3,with an average of 5.1 μg/m3.The diurnai variation of BC exhibited a bimodal distribution,with peaks at 07:00 and 18:00.The morning peak was larger than the evening peak.The mass percentages of BC in PM2.5 and PM10 were 7.1%and 4.8%,respectively.The absorption coefficient of BC was calculated to be 44.4 Mm-1,which accounted for 11.1%of the total aerosol extinction.BC was mainly emitted from local sources in southwestern Jiaxing where BC concentrations were generally greater than 11 μg/m3 during the measurement period.Correlation analysis indicated that the main sources of BC were motor vehicle exhaust,and domestic and industrial combustion. 相似文献