全文获取类型
收费全文 | 1645篇 |
免费 | 295篇 |
国内免费 | 143篇 |
专业分类
化学 | 1026篇 |
晶体学 | 9篇 |
力学 | 86篇 |
综合类 | 28篇 |
数学 | 221篇 |
物理学 | 713篇 |
出版年
2024年 | 4篇 |
2023年 | 32篇 |
2022年 | 44篇 |
2021年 | 45篇 |
2020年 | 61篇 |
2019年 | 65篇 |
2018年 | 54篇 |
2017年 | 36篇 |
2016年 | 70篇 |
2015年 | 66篇 |
2014年 | 81篇 |
2013年 | 108篇 |
2012年 | 129篇 |
2011年 | 146篇 |
2010年 | 86篇 |
2009年 | 91篇 |
2008年 | 84篇 |
2007年 | 92篇 |
2006年 | 93篇 |
2005年 | 78篇 |
2004年 | 76篇 |
2003年 | 49篇 |
2002年 | 49篇 |
2001年 | 27篇 |
2000年 | 27篇 |
1999年 | 40篇 |
1998年 | 35篇 |
1997年 | 25篇 |
1996年 | 37篇 |
1995年 | 29篇 |
1994年 | 27篇 |
1993年 | 26篇 |
1992年 | 24篇 |
1991年 | 23篇 |
1990年 | 19篇 |
1989年 | 25篇 |
1988年 | 21篇 |
1987年 | 12篇 |
1986年 | 9篇 |
1985年 | 8篇 |
1984年 | 2篇 |
1983年 | 3篇 |
1982年 | 2篇 |
1981年 | 2篇 |
1980年 | 4篇 |
1979年 | 4篇 |
1978年 | 2篇 |
1976年 | 4篇 |
1973年 | 4篇 |
1930年 | 1篇 |
排序方式: 共有2083条查询结果,搜索用时 15 毫秒
151.
Jinchao Lou Xiaoyu Zhang Prof. Michael D. Best 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(1):20-25
Advancements in the field of liposomal drug carriers have culminated in greatly improved delivery properties. An important aspect of this work entails development of designer liposomes for release of contents triggered by environmental changes. The majority of these systems are driven by chemical reactions in the presence of different stimuli. However, a promising new paradigm instead focuses on molecular recognition events as the impetus for content release. In certain cases, these platforms exploit synthetic lipid switches designed to undergo conformational changes upon binding to target ions or molecules that perturb membrane assembly, thereby triggering cargo release. Examples of this approach reported thus far showcase how rational design of lipid switches can result in dramatic changes in lipid assembly properties. These strategies show great promise for opening up new pathophysiological stimuli that can be harnessed for programmed content release in drug delivery applications. 相似文献
152.
Lou Yuke Ye Zhengmao Wang Shuxian Liu Shuxin Cheng Xin 《Journal of Thermal Analysis and Calorimetry》2019,135(4):2031-2038
Journal of Thermal Analysis and Calorimetry - Ettringite is an important cement hydration product and has a significant effect on cement performance. H-ettringite (synthesized by hydration... 相似文献
153.
The aim of this work was to further investigate the anticancer potential of Juglans mandshurica Maxim, including the separation of active constituents and their anti-proliferative effects with underlying mechanism of action. Five alkaloids (1–5) were isolated from the bark of J. mandshurica. Among them, 1 showed the highest cytotoxic activities against Hep3B and HepG2 cells with an IC50 values of 61.80 and 56.24 μM, respectively. Therefore, the cellular mechanism involved 1 was subsequently studied. Our results showed that 1 markedly caused apoptosis and autophagy, but without cell cycle arrest in HepG2 cells. Interestingly, only autophagic cell death was induced in 1-treated Hep3B cells. It is concluded that the isolated alkaloids exerted a certain anti-hepatoma potential, and our results may provide a basis for the further investigation of the alkaloids extracted from J. mandshurica. 相似文献
154.
Xin-Yue Lou Dr. Nan Song Prof. Ying-Wei Yang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(51):11975-11982
Organic luminescent materials with high quantum yields and/or white-light-emitting properties in particular play a crucial role in labeling and optoelectronic devices. In this work we have synthesized a new 2,3,6,7-tetramethoxy-9,10-di-p-tolylanthracene-bridged pillar[5]arene dimer with persistent mazarine blue fluorescent emission and much higher quantum yields in both solution and the solid state in comparison with its corresponding emissive linker without pillarene units, which exhibits typical aggregation-caused quenching. According to the fluorescence data and single-crystal analyses, their contrasting fluorescent performances can be rationally ascribed to their different stacking structures and intermolecular interactions. Three fluorescent guests containing different chromophores and/or terminal binding sites have also been synthesized to interact with the pillar[5]arene dimer to construct supramolecular ensembles with highly controllable luminescence, taking advantage of the stimuli-responsive properties of the supramolecular host–guest interactions. Intriguingly, multicolor fluorescence, including white-light emission (0.31, 0.35), which is in high demand, has been achieved by tuning the molar ratio of the host and guest and/or by changing the solvent system. This strategy holds great potential for the design and development of fluorescent materials with high quantum yields, controllable emission wavelength, and good stimuli-responsiveness. 相似文献
155.
Lumps and their interaction solutions of a (2+1)-dimensional generalized potential Kadomtsev-Petviashvili equation 下载免费PDF全文
A (2+1)-dimensional generalized potential Kadomtsev-Petviashvili (gpKP) equation which possesses a Hirota bilinear form is constructed. The lump waves are derived by using a positive quadratic function solution. By combining an exponential function with a quadratic function, an interaction solution between a lump and a one-kink soliton is obtained. Furthermore, an interaction solution between a lump and a two-kink soliton is presented by mixing two exponential functions with a quadratic function. This type of lump wave just appears to a line $k_2x+k_3y+k_4t+k_5 \sim 0$. We call this kind of lump wave is a special rogue wave. Some visual figures are depicted to explain the propagation phenomena of these interaction solutions. 相似文献
156.
臧宏亮 叶沿林 李智焕 王建松 楼建玲 李奇特 葛愉成 杨晓菲 李晶 蒋伟 冯俊 刘强 杨彪 陈志强 刘洋 吴鸿毅 牛晨阳 李晨光 王春光 王翔 刘威 高见 余翰舟 马军兵 马朋 白真 杨彦云 金仕纶 卢飞 《中国物理C(英文版)》2018,42(7):074003-074003
An experiment for p(~(14)C,~(14)C~*→~(10)Be+α)p inelastic excitation and decay was performed in inverse kinematics at a beam energy of 25.3 Me V/u.A series of~(14)C excited states,including a new one at 18.3(1)Me V,were observed which decay to various states of the final nucleus of~(10)Be.A specially designed telescope system,installed around zero degrees,played an essential role in detecting the resonant states near theα-separation threshold.A state at 14.1(1)Me V is clearly identified,being consistent with the predicted band-head of the molecular rotational band characterized by theπ-bond linear chain configuration.Further clarification of the properties of this exotic state is suggested by using appropriate reaction tools. 相似文献
157.
Libo Li Qihong Lou Jun Zhou Jingxing Dong Yunrong Wei Songtao Du Bing He 《Optics Communications》2008,281(4):655-657
To get high output power with good beam quality, a tapered section is introduced to large-mode-area (LMA) Yb-doped fiber laser. Output characteristics of the fiber laser without tapered section and with tapered section are compared experimentally. When the launched pump power is 119.1 W, 77.9 W with M2 3.08 and 56.4 W with M2 1.14 can be obtained, respectively. The corresponding slope efficiencies are 71.8% and 54.1%, respectively. Although output power of the tapered fiber laser has 30.6% penalty, brightness of it is as much as 5.28 times of the fiber laser without tapered section. Moreover, spectra of them are measured. It is found that tapered section makes lasing wavelength of the fiber laser shorter. 相似文献
158.
认为物质的质量(能量)存在形式可分为两部分,一部分是以纯物质形式存在的,另一部分是以纯重力场形式存在的.物质质量(能量)这两种形式各自对应着相应的能量 动量张量,物质总的能量-动量张量可表示为Tμν=T(Ⅰ)μν+T(Ⅱ)μν,这里,T(Ⅰ)μν,T(Ⅱ)μν分别代表物质纯物质部分和纯重力场部分的能量-动量张量.通过类比电磁理论,定义:ωμ≡-c2gμ0/g00,并引入一个反对称张量Dμν=ωμ/xν-ων/xμ,则物质纯重力场部分的能量-动量张量为T(Ⅱ)μν=(DμρDρν-gμνDαβDαβ/4
关键词:
能量-动量张量
纯重力场
重力场方程
标量重力势
矢量重力势 相似文献
159.
160.