全文获取类型
收费全文 | 21998篇 |
免费 | 4038篇 |
国内免费 | 3507篇 |
专业分类
化学 | 16464篇 |
晶体学 | 391篇 |
力学 | 1393篇 |
综合类 | 251篇 |
数学 | 2372篇 |
物理学 | 8672篇 |
出版年
2024年 | 78篇 |
2023年 | 463篇 |
2022年 | 789篇 |
2021年 | 939篇 |
2020年 | 1028篇 |
2019年 | 1010篇 |
2018年 | 817篇 |
2017年 | 850篇 |
2016年 | 1183篇 |
2015年 | 1189篇 |
2014年 | 1452篇 |
2013年 | 1866篇 |
2012年 | 2149篇 |
2011年 | 2106篇 |
2010年 | 1595篇 |
2009年 | 1412篇 |
2008年 | 1591篇 |
2007年 | 1282篇 |
2006年 | 1173篇 |
2005年 | 978篇 |
2004年 | 815篇 |
2003年 | 654篇 |
2002年 | 654篇 |
2001年 | 568篇 |
2000年 | 428篇 |
1999年 | 424篇 |
1998年 | 307篇 |
1997年 | 255篇 |
1996年 | 287篇 |
1995年 | 207篇 |
1994年 | 201篇 |
1993年 | 160篇 |
1992年 | 119篇 |
1991年 | 121篇 |
1990年 | 73篇 |
1989年 | 58篇 |
1988年 | 53篇 |
1987年 | 32篇 |
1986年 | 55篇 |
1985年 | 38篇 |
1984年 | 13篇 |
1983年 | 18篇 |
1982年 | 13篇 |
1981年 | 11篇 |
1980年 | 4篇 |
1979年 | 3篇 |
1975年 | 2篇 |
1974年 | 2篇 |
1957年 | 8篇 |
1936年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
941.
以离子液体溴化(1-己基-3-甲基咪唑盐)作为电解质和掺杂剂采用电化学一步法制备了微纳米复合结构的聚(3,4-乙烯基二氧噻吩)薄膜,薄膜由槽内排布着纳米珠链的棒状结构组成. 研究表明,通过控制电流密度的大小,可以调节棒状结构和珠状结构的平均直径. 离子液体中的咪唑阳离子和对阴离子均掺杂到聚合物中,该薄膜具有可逆的电化学活性及水下超疏油特性. 相似文献
942.
943.
Peng Chen Zhuyuan Wang Shenfei Zong Hui Chen Dan Zhu Yuan Zhong Yiping Cui 《Analytical and bioanalytical chemistry》2014,406(25):6337-6346
p-Aminothiophenol (pATP) functionalized multi-walled carbon nanotubes (MWCNTs) have been demonstrated as an efficient pH sensor for living cells. The proposed sensor employs gold/silver core-shell nanoparticles (Au@Ag NPs) functionalized MWCNTs hybrid structure as the surface-enhanced Raman scattering (SERS) substrate and pATP molecules as the SERS reporters, which possess a pH-dependent SERS performance. By using MWCNTs as the substrate to be in a state of aggregation, the pH sensing range could be extended to pH 3.0~14.0, which is much wider than that using unaggregated Au@Ag NPs without MWCNTs. Furthermore, the pH-sensitive performance was well retained in living cells with a low cytotoxicity. The developed SERS-active MWCNTs-based nanocomposite is expected to be an efficient intracellular pH sensor for bio-applications. 相似文献
944.
945.
PPh3‐Catalyzed Ring‐Expansion Reactions of Sulfamate‐Derived Cyclic Imines with Acetylenedicarboxylates 下载免费PDF全文
Zhilin Yang Hao Yu Lei Zhang Hang Wei Dr. Yumei Xiao Lanzhen Chen Dr. Hongchao Guo 《化学:亚洲杂志》2014,9(1):313-318
The PPh3‐catalyzed ring‐expansion reaction of sulfamate‐derived cyclic imines with acetylenedicarboxylates has been developed. The reaction works quite efficiently under very mild conditions to afford benzo[g][1,2,3]oxathiazocine‐4,5‐dicarboxylate 2,2‐dioxide derivatives in high yields. 相似文献
946.
Supramolecular Complexes of Multivalent Cholesterol‐Containing Polymers to Solubilize Carbon Nanotubes in Apolar Organic Solvents 下载免费PDF全文
Jules Zeuna Nguendia Weiheng Zhong Alexandre Fleury Guillaume De Grandpré Prof. Armand Soldera Prof. Ribal Georges Sabat Prof. Jerome P. Claverie 《化学:亚洲杂志》2014,9(5):1356-1364
Copolymers of 2‐ethylhexyl acrylate (EHA) and cholesteryloxycarbonyl‐2‐hydroxymethacrylate (CEM) were prepared by reversible addition–fragmentation chain‐transfer (RAFT) polymerization. Supramolecular complexes of these copolymers with carbon nanotubes (CNTs) were soluble in THF, toluene, and isooctane. The colloidal solutions remained stable for months without aggregation. The rationale for the choice of CEM was based on the high adsorption energy of cholesterol on the CNT surface, as computed by DFT calculations. Adsorption isotherms were experimentally measured for copolymers of various architectures (statistical, diblock, and star copolymers), thereby demonstrating that 2–5 cholesterol groups were adsorbed per polymer chain. Once the supramolecular complex had dried, the CNTs could be easily resolubilized in isooctane without the need for high‐power sonication and in the absence of added polymer. Analysis by atomic force microscopy (AFM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) indicated that the CNTs were devoid of bundles. The supramolecular complexes could also be employed in an inverse emulsion polymerization of 2‐hydroxyethylmethacrylate (HEMA) in isooctane and dodecane, thereby leading to the formation of a continuous polymeric sheath around the CNTs. Thus, this technique leads to the formation of very stable dispersions in non‐polar organic solvents, without altering the fundamental properties of the CNTs. 相似文献
947.
Hongren Chen Fengying Hong Dr. Guang Shao Dr. Deyu Hang Lei Zhao Prof. Zhuo Zeng 《化学:亚洲杂志》2014,9(12):3418-3430
By using three synthetic protocols, a series of fluorocarbon and hydrocarbon N‐heterocyclic imidazole‐based liquid crystals (LCs) and related imidazolium‐based ionic liquid crystals (ILCs) have been prepared. The ring size of the N‐heterocycle and the length of the N‐terminal chain (on the imidazolium unit in the ILCs) were modified, and the influence of these structural parameters on liquid‐crystal phases was investigated by means of polarizing optical microscopy (POM), differential scanning calorimetry (DSC), and X‐ray diffraction (XRD). These new ILCs exhibit a disordered smectic phase (SmA), good thermal stabilities, a broad smectic phase range, a high dipole moment, relatively low melting points, but high clearing points and strong emission fluorescence relative to imidazole‐based LCs. These encouraging results have led us to believe these fluorocarbon and hydrocarbon N‐heterocyclic imidazole‐based LCs and related imidazolium‐based ILCs could be used as new liquid‐crystalline materials. 相似文献
948.
Xiaojuan Liao Lei Guo Junxia Chang Sha Liu Meiran Xie Guosong Chen 《Macromolecular rapid communications》2015,36(16):1492-1497
Pillararene‐containing thermoresponsive polymers are synthesized via reversible addition–fragmentation chain transfer polymerization using pillararene derivatives as the effective chain transfer agents for the first time. These polymers can self‐assemble into micelles and form vesicles after guest molecules are added. Furthermore, such functional polymers can be further applied to prepare hybrid gold nanoparticles, which integrate the thermoresponsivity of polymers and molecular recognition of pillararenes.
949.
Dongliang Gao Andrey Novitsky Tianhang Zhang Fook Chiong Cheong Lei Gao Chwee Teck Lim Boris Luk'yanchuk Cheng‐Wei Qiu 《Laser \u0026amp; Photonics Reviews》2015,9(1):75-82
This paper investigates the singular optics of nonparaxial light beams in the near field when the light behaves as a tractor beam. New insights into the optical pulling force, which is usually represented by integrating the stress tensor at a black box enclosing the object, are interpreted by the optical singularity of the Poynting vector. The negative nonconservative pulling force originates from the transfer of the azimuthal Poynting vector to the longitudinal component partly owing to the presence of a scatterer. The separatrice pattern and singularity shifts of the Poynting vector unanimously exhibit a differentiable near‐field distribution in the presence of optical pulling force. A new method is established to calculate the near‐field optical force using the differential Poynting vector in the far field. The results obtained provide a clear physical interpretation of the light–matter interaction and manifest the significance of singular optics in manipulating objects.
950.