全文获取类型
收费全文 | 1107篇 |
免费 | 69篇 |
国内免费 | 93篇 |
专业分类
化学 | 425篇 |
晶体学 | 6篇 |
力学 | 45篇 |
综合类 | 7篇 |
数学 | 88篇 |
物理学 | 215篇 |
综合类 | 483篇 |
出版年
2024年 | 10篇 |
2023年 | 23篇 |
2022年 | 25篇 |
2021年 | 30篇 |
2020年 | 45篇 |
2019年 | 34篇 |
2018年 | 37篇 |
2017年 | 35篇 |
2016年 | 45篇 |
2015年 | 47篇 |
2014年 | 77篇 |
2013年 | 67篇 |
2012年 | 84篇 |
2011年 | 72篇 |
2010年 | 45篇 |
2009年 | 49篇 |
2008年 | 68篇 |
2007年 | 64篇 |
2006年 | 51篇 |
2005年 | 41篇 |
2004年 | 32篇 |
2003年 | 16篇 |
2002年 | 19篇 |
2001年 | 21篇 |
2000年 | 19篇 |
1999年 | 33篇 |
1998年 | 34篇 |
1997年 | 24篇 |
1996年 | 25篇 |
1995年 | 14篇 |
1994年 | 17篇 |
1993年 | 15篇 |
1992年 | 12篇 |
1991年 | 12篇 |
1990年 | 10篇 |
1989年 | 6篇 |
1988年 | 6篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1985年 | 1篇 |
排序方式: 共有1269条查询结果,搜索用时 15 毫秒
141.
准噶尔盆地石炭系火山岩储层主控因素分析 总被引:15,自引:1,他引:14
通过对准噶尔盆地石炭系火山岩油气藏岩芯的详细观察以及对储层岩石物性数据的统计分析,认为构造运动、岩性与岩相、风化淋滤作用是控制准噶尔盆地石炭系火山岩储层的主要因素。火山岩储集空间类型分为原生裂缝、原生孔隙、次生裂缝、次生孔隙四类。储层的渗流能力主要由裂缝决定。风化壳是准噶尔盆地石炭系火山岩储层的主要类型。优质储层主要分布在风化壳顶面以下250 m距离以内,其中环坳陷分布的古隆起部位更为有利。距离风化壳顶面越远,孔隙和裂缝充填程度越高,火山岩储集性能越差。 相似文献
142.
Xiaomin Tang 《Linear and Multilinear Algebra》2018,66(2):250-259
In this paper, we prove that a biderivation of a finite-dimensional complex simple Lie algebra without the restriction of being skewsymmetric is an inner biderivation. As an application, the biderivation of a general linear Lie algebra is presented. In particular, we find a class of a non-inner and non-skewsymmetric biderivations. Furthermore, we also obtain the forms of the linear commuting maps on the finite-dimensional complex simple Lie algebra or general linear Lie algebra. 相似文献
143.
We mainly study the super-biderivations of not-finitely graded Lie superalgebras related to generalized super-Virasoro algebras. In particular, we prove that all super-biderivations of not-finitely graded Lie superalgebras related to generalized super-Virasoro algebras are inner. 相似文献
144.
In this article, we investigate robust optimization equilibria with two players, in which each player can neither evaluate his opponent's strategy nor his own cost matrix accurately while may estimate a bounded set of the strategy or cost matrix. We obtain a result that solving this equilibria can be formulated as solving a second-order cone complementarity problem under an ellipsoid uncertainty set or a mixed complementarity problem under a box uncertainty set. We present some numerical results to illustrate the behaviour of robust optimization equilibria. 相似文献
145.
Wei Wei Xia Zhang Hui Yu Yongqing Huang Xiaomin Ren 《Photonics and Nanostructures》2013,11(3):279-287
The plasmonic waveguiding properties of the gap plasmon mode between two adjacent silver nanowires with a substrate are theoretically investigated using finite element method. The results show that there is a critical gap distance between two silver nanowires which approximately equals to the radius of the nanowires. When the gap distance is less than the critical distance, the influence of the substrate on the gap plasmon mode can be neglected. The gap plasmon mode has a combination of high confinement and long propagation length. Moreover, the plasmonic waveguiding properties of the gap plasmon mode are not sensitive to the wire-to-substrate distance between silver nanowires and the substrate. 相似文献
146.
Yuefeng Song Le Lin Weicheng Feng Xiaomin Zhang Qiao Dong Xiaobao Li Houfu Lv Qingxue Liu Fan Yang Zhi Liu Guoxiong Wang Xinhe Bao 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(45):16189-16192
Oxidative dehydrogenation of ethane (ODE) is limited by the facile deep oxidation and potential safety hazards. Now, electrochemical ODE reaction is incorporated into the anode of a solid oxide electrolysis cell, utilizing the oxygen species generated at anode to catalytically convert ethane. By infiltrating γ‐Al2O3 onto the surface of La0.6Sr0.4Co0.2Fe0.8O3‐δ‐Sm0.2Ce0.8O2‐δ (LSCF‐SDC) anode, the ethylene selectivity reaches as high as 92.5 %, while the highest ethane conversion is up to 29.1 % at 600 °C with optimized current and ethane flow rate. Density functional theory calculations and in situ X‐ray photoelectron spectroscopy characterizations reveal that the Al2O3/LSCF interfaces effectively reduce the amount of adsorbed oxygen species, leading to improved ethylene selectivity and stability, and that the formation of Al‐O‐Fe alters the electronic structure of interfacial Fe center with increased density of state around Fermi level and downshift of the empty band, which enhances ethane adsorption and conversion. 相似文献
147.
利用酸水解稻壳中的半纤维素制备木糖, 并将糖渣经过炭化后分离出碳和硅, 碳采用稀碱溶液活化改性制备电容炭, 硅采用水热法合成了硅酸钙晶须, 从而使稻壳所有组分得到充分利用. 采用循环伏安(CV)和恒流充放电(GCD)研究了电容炭的电化学性能. 通过X射线衍射(XRD)和扫描电子显微镜(SEM)对所得硅酸钙晶须的结构和形貌进行了表征. 实验结果表明, 稻壳酸水解的最优条件为硫酸浓度7%(质量分数)、 固液比(g/mL)为1:8、 反应时间为2.0 h, 在该条件下, 一次水解、 二次水解和三次水解的木糖收率(Y1/Y2/Y3)和浓度(质量分数, C1/C2/C3)都能达到最大值, Y1=98.5%, C1=3.6%; Y2=85.4%, C2=6.3%; Y3=76.6%, C3=9.0%. 采用15 mL 8%(质量分数) NaOH稀碱溶液活化改性制得的电容炭(AC/15)比电容值为77.32 F/g, 而且具有较好的倍率性和循环稳定性; 硅酸钙晶须为扫帚状针钠钙石晶须. 相似文献
148.
Liang Chunyong Zhang Xiaomin Zhao Yan Tan Taizhe Zhang Yongguang 《Journal of Solid State Electrochemistry》2019,23(2):565-572
Journal of Solid State Electrochemistry - A three-dimensionally (3D) ordered macro/mesoporous carbon (3DOMC) is synthesized by one-step template method as a TiO2 supporter, and this TiO2/3DOMC... 相似文献
149.
Supercontinuum generation (SCG) using a femtosecond Ti:Sapphire laser as a pump source and a nanofiber as a nonlinear element is investigated by numerical modeling. Many parameters are taken into account involving input pulse duration, peak power and diameter of the nanofiber. The results show that the narrower the input pulse is, the easier the SCG could be observed. The relation between the spectrum broadening and the diameter of nanofiber is not a direct proportion. According to our simulation, the dimension of the nanofiber plays an important role in effecting the dispersion and then the generation of supercontinuum. 相似文献
150.