全文获取类型
收费全文 | 84841篇 |
免费 | 8672篇 |
国内免费 | 5230篇 |
专业分类
化学 | 52713篇 |
晶体学 | 845篇 |
力学 | 5046篇 |
综合类 | 367篇 |
数学 | 8388篇 |
物理学 | 31384篇 |
出版年
2025年 | 69篇 |
2024年 | 1031篇 |
2023年 | 1850篇 |
2022年 | 2978篇 |
2021年 | 3479篇 |
2020年 | 3951篇 |
2019年 | 3607篇 |
2018年 | 2638篇 |
2017年 | 2400篇 |
2016年 | 3688篇 |
2015年 | 3605篇 |
2014年 | 4296篇 |
2013年 | 5416篇 |
2012年 | 6822篇 |
2011年 | 6815篇 |
2010年 | 4527篇 |
2009年 | 4304篇 |
2008年 | 4648篇 |
2007年 | 4140篇 |
2006年 | 3781篇 |
2005年 | 3176篇 |
2004年 | 2493篇 |
2003年 | 1940篇 |
2002年 | 1774篇 |
2001年 | 1506篇 |
2000年 | 1375篇 |
1999年 | 1553篇 |
1998年 | 1327篇 |
1997年 | 1306篇 |
1996年 | 1305篇 |
1995年 | 1069篇 |
1994年 | 942篇 |
1993年 | 785篇 |
1992年 | 698篇 |
1991年 | 601篇 |
1990年 | 521篇 |
1989年 | 409篇 |
1988年 | 353篇 |
1987年 | 295篇 |
1986年 | 261篇 |
1985年 | 216篇 |
1984年 | 159篇 |
1983年 | 112篇 |
1982年 | 94篇 |
1981年 | 76篇 |
1980年 | 75篇 |
1979年 | 33篇 |
1978年 | 33篇 |
1977年 | 41篇 |
1976年 | 32篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
101.
The assembly of[Et4N][Tp*WS3](1) with CuX (Tp* =hydridotris(3,5-dimethylpyrazol-1-yl)borate;X =Cl,Br,and I) or[Cu(MeCN)4][PF6]in the presence of tetratopic liga... 相似文献
102.
In this paper, by capturing the atomic information and reflecting the behaviour governed by the nonlinear potential function,
an analytical molecular mechanics approach is proposed. A constitutive relation for single-walled carbon nanotubes (SWCNT’s)
is established to describe the nonlinear stress-strain curve of SWCNT’s and to predict both the elastic properties and breaking
strain of SWCNT’s during tensile deformation. An analysis based on the virtual internal bond (VIB) model proposed by P. Zhang
et al. is also presented for comparison. The results indicate that the proposed molecular mechanics approach is indeed an
acceptable analytical method for analyzing the mechanical behavior of SWCNT’s.
The project supported by the National Natural Science Foundation of China (10121202, 90305015 and 10328203), the Key Grant
Project of Chinese Ministry of Education (0306) and the Research Grants Council of the Hong Kong Special Administrative Region,
China (HKU 7195/04E). 相似文献
103.
Feng Wang Rui Zhao Zheng-Xiong Wang Yue Zhang Zhan-Hong Lin Shi-Jie Liu CFETR Team 《中国物理快报》2021,(5):36-40
Fusion born α particle confinement is one of the most important issues in burning plasmas,such as ITER and CFETR.However,it is extremely complex due to the nonequilibrium characteristics,and multiple temporal and spatial scales coupling with background plasma.A numerical code using particle orbit tracing method(PTC)has been developed to study energetic particle confinement in tokamak plasmas.Both full orbit and drift orbit solvers are implemented to analyze the Larmor radius effects on α particle confinement.The elastic collisions between alpha particles and thermal plasma are calculated by a Monte Carlo method.A triangle mesh in poloidal section is generated for electromagnetic fields expression.Benchmark between PTC and ORBIT has been accomplished for verification.For CFETR burning plasmas,PTC code is used for α particle source and slowing down process calculation in 2D equilibrium.In future work,3D field like toroidal field ripples,Alfven and magnetohydrodynamics instabilities perturbation inducing α particle transport will be analyzed. 相似文献
104.
The understanding of amphiphilic block copolymers(ABC)in encapsulation and transport of inorganic nanomedicines is highly desired.Still,it remains limited due to the challenges in the fabrication of nanoassemblies(NAs)with highly-controlled shape and loading of nanoparticles.Herein,through growth regulation of luminescent gold nanoparticles(Au NPs)by different reductants with ABC pluronic F127 as a template,a straightforward strategy is reported for in-situ fabrication of three wellcontrolled gold NAs(Au NAs)that display tunable shapes from spherical to elongated nanostructures and controllable surface chemistry and loading of Au NPs with distinct emissions but identical individual Au NP size.The three Au NAs exhibit tailored invivo transport behaviours:those with spherical shape and more hydrophilic surface show longer blood retention with higher tumor-targeting efficiency(~25.3%injection dose/g)and excellent long-term near-infrared tumor imaging even after 96 h postinjection.These findings provide a useful guidance in designing specific nanostructures for future nanomedicine transport. 相似文献
105.
Shunli Ni Sheng Ma Yuhang Zhang Jie Yuan Haitao Yang Zouyouwei Lu Ningning Wang Jianping Sun Zhen Zhao Dong Li Shaobo Liu Hua Zhang Hui Chen Kui Jin Jinguang Cheng Li Yu Fang Zhou Xiaoli Dong Jiangping Hu Hong-Jun Gao Zhongxian Zhao 《中国物理快报》2021,(5):133-137
We systematically measure the superconducting(SC) and mixed state properties of high-quality CsV_3 Sb_5 single crystals with T_c~3.5 K.We find that the upper critical field H_(c2)(T) exhibits a large anisotropic ratio of H_(c2)~(ab)/H_(c2)~c~9 at zero temperature and fitting its temperature dependence requires a minimum two-band effective model.Moreover,the ratio of the lower critical field,H_(c1)~(ab)/H_(c1)~c,is also found to be larger than 1,which indicates that the in-plane energy dispersion is strongly renormalized near Fermi energy.Both H_(c1)(T) and SC diamagnetic signal are found to change little initially below T_c~3.5 K and then to increase abruptly upon cooling to a characteristic temperature of ~2.8 K.Furthermore,we identify a two-fold anisotropy of in-plane angular-dependent magnetoresistance in the mixed state.Interestingly,we find that,below the same characteristic T~2.8 K,the orientation of this two-fold anisotropy displays a peculiar twist by an angle of 60° characteristic of the Kagome geometry.Our results suggest an intriguing superconducting state emerging in the complex environment of Kagome lattice,which,at least,is partially driven by electron-electron correlation. 相似文献
106.
Braverman and Kazhdan(2000) introduced influential conjectures aimed at generalizing the Fourier transform and the Poisson summation formula. Their conjectures should imply that quite general Langlands L-functions have meromorphic continuations and functional equations as predicted by Langlands' functoriality conjecture. As an evidence for their conjectures, Braverman and Kazhdan(2002) considered a setting related to the so-called doubling method in a later paper and proved the corresponding Poisson summation formula under restrictive assumptions on the functions involved. The connection between the two papers is made explicit in the work of Li(2018). In this paper, we consider a special case of the setting in Braverman and Kazhdan's later paper and prove a refined Poisson summation formula that eliminates the restrictive assumptions of that paper. Along the way we provide analytic control on the Schwartz space we construct; this analytic control was conjectured to hold(in a slightly different setting) in the work of Braverman and Kazhdan(2002). 相似文献
107.
The simulation of particle fluidization behavior in a complex geometry with a large number of particles is challenging owing to the complexity of unstructured c... 相似文献
108.
描述一种微光像增强器综合测试系统的总体设计。设计采用了组合结构,使系统只用单一的光源就可以测试微光像增强器九项光量子类和几何类的参数,具有以往几台常规测试仪器功能的总和。系统对各参数测量的不确定度2~4%。 相似文献
109.
Liu J Gardel ML Kroy K Frey E Hoffman BD Crocker JC Bausch AR Weitz DA 《Physical review letters》2006,96(11):118104
We exploit the power of microrheology to measure the viscoelasticity of entangled F-actin solutions at different length scales from 1 to 100 microm over a wide frequency range. We compare the behavior of single probe-particle motion to that of the correlated motion of two particles. By varying the average length of the filaments, we identify fluctuations that dissipate diffusively over the filament length. These provide an important relaxation mechanism of the elasticity between 0.1 and 30 rad/sec. 相似文献
110.
Ji-Wu Huang Chuang-Jun Li Jing-Zhi Yang Chuan Li Yu Zhang Ke Liu Yue Yu Jian-Dong Jiang Dong-Ming Zhang 《中国化学》2021,(5):1129-1137
Main observation and conclusion
Eight new polycyclic phloroglucinol meroterpenoids guajamers A-H (1-8),a methylated benzoylphloroglucinol meroterpenoid guajamer... 相似文献