全文获取类型
收费全文 | 6434篇 |
免费 | 1625篇 |
国内免费 | 483篇 |
专业分类
化学 | 1462篇 |
晶体学 | 42篇 |
力学 | 838篇 |
综合类 | 81篇 |
数学 | 753篇 |
物理学 | 5366篇 |
出版年
2024年 | 11篇 |
2023年 | 46篇 |
2022年 | 130篇 |
2021年 | 161篇 |
2020年 | 173篇 |
2019年 | 156篇 |
2018年 | 132篇 |
2017年 | 208篇 |
2016年 | 270篇 |
2015年 | 184篇 |
2014年 | 383篇 |
2013年 | 488篇 |
2012年 | 412篇 |
2011年 | 496篇 |
2010年 | 387篇 |
2009年 | 483篇 |
2008年 | 576篇 |
2007年 | 473篇 |
2006年 | 459篇 |
2005年 | 383篇 |
2004年 | 337篇 |
2003年 | 291篇 |
2002年 | 266篇 |
2001年 | 237篇 |
2000年 | 206篇 |
1999年 | 175篇 |
1998年 | 155篇 |
1997年 | 119篇 |
1996年 | 153篇 |
1995年 | 85篇 |
1994年 | 89篇 |
1993年 | 66篇 |
1992年 | 51篇 |
1991年 | 41篇 |
1990年 | 42篇 |
1989年 | 39篇 |
1988年 | 31篇 |
1987年 | 37篇 |
1986年 | 18篇 |
1985年 | 21篇 |
1984年 | 20篇 |
1983年 | 6篇 |
1982年 | 13篇 |
1981年 | 8篇 |
1980年 | 6篇 |
1979年 | 3篇 |
1978年 | 4篇 |
1976年 | 3篇 |
1970年 | 2篇 |
1936年 | 1篇 |
排序方式: 共有8542条查询结果,搜索用时 15 毫秒
1.
Prof. Dr. Peter Hess 《Chemphyschem》2022,23(6):e202100880
In the periodic table the position of each atom follows the ‘aufbau’ principle of the individual electron shells. The resulting intrinsic periodicity of atomic properties determines the overall behavior of atoms in two-dimensional (2D) bonding and structure formation. Insight into the type and strength of bonding is the key in the discovery of innovative 2D materials. The primary features of 2D bonding and the ensuing monolayer structures of the main-group II–VI elements result from the number of valence electrons and the change of atom size, which determine the type of hybridization. The results reveal the tight connection between strength of bonding and bond length in 2D networks. The predictive power of the periodic table reveals general rules of bonding, the bonding-structure relationship, and allows an assessment of published data of 2D materials. 相似文献
2.
The Electrostatic Discharge (ESD) phenomenon has been described through the IEC 61000-4-2. ESD current parameters' values, have been set in this Standard. The theoretical ESD current waveform defined in this standard, describing the conventional Contact discharge mode, needs to be re-evaluated on the basis of accurate experimental data. Even though the standard deals with commercial ESD generators, its goal is to simulate the natural phenomenon as good as possible. More and accurate data may contribute to the better simulation of the natural phenomenon. New values and better comprehension of the phenomenon demand new measurements based on high end measuring equipment. Such works and publications have been carried out the past years. Yet, the need to systematize and integrate this work remains. Larger and trust-worthy series of measurements need to be carried out and presented clearly.This paper deals with new ESD-current data, taken with broadband equipment. New and more detailed measurements like these, were never before taken at such a large number of individuals. The goal of this work is that the data acquired can serve as a basis for re-evaluating the conventional approach of the scientific community to the ESD event.In this paper, using a broadband measuring system, new parameters' values are measured and relations are presented, following standard statistical procedures. The results, which occur from measurements carried out on tenths of human individuals, are questioning the Standard in many points. A new way of approaching the standardization of the ESD current is proposed, as the excuse of the poor measuring equipment that sets barriers on the measuring accuracy, does not apply any more. The charging voltages of 500 V and 1000 V were also examined since such range of voltages are often met at ESD events and they are considered very harmful. 相似文献
3.
The possibility of realizing SASE Free Election Laser in x-ray waveband with EM-wave wiggler is studied in this paper. SASE effect including saturation length, saturation power and nonlinear process is explored through a 3-D simulation code. A utilization of seed light from laser plasma x-ray is also analyzed, which demonstrates the feature of shortening the interaction length for saturation. The results show that sizeable output power of x-ray laser would be generated with a middle energy electron beam. 相似文献
4.
5.
6.
计算全息检测非球面干涉场的理论分析与实验结果 总被引:2,自引:0,他引:2
本文应用光学全息术及傅里叶光学的理论对计算全息图干涉检测非球面面形的光路及干涉场进行了理论分析,提出了其干涉场为不定域干涉的观点,并在实验中予以证实. 相似文献
7.
超强脉冲激光在低密度等离子体中的相对论自导引效应 总被引:1,自引:1,他引:0
分析了相对论条件下激光超短脉冲在等离子体中的传输特性 ,在傍轴近似和慢变振幅近似条件下 ,推导了折射率、电子密度、静电场以及电子空腔尺度的表达式。当激光功率超过产生自导引阈值功率时 ,激光束斑沿着传输光轴方向振荡。在有质动力产生的压力非常强时 ,聚焦光束中央部分的电子被全部排开形成电子空腔。给出了电子空腔的尺寸以及在出现电子空腔时的处理方法。在超过形成电子空腔的阈值功率 (Pc≈ 2 .5TW )时 ,空腔的尺度几乎与激光功率无关 ,这意味着电子空腔阻止了激光脉冲的进一步聚焦。 相似文献
8.
9.
空间遥感相机长条反射镜较圆反射镜的整体刚度相差很大,整个组件在随火箭发射过程中因力学环境引起的自身位置改变导致面形的微小畸变从而对成像质量造成严重影响。因此,反射镜组件的设计就成为整个相机系统研制的重点与难点之一。对其进行科学、严谨的力学环境仿真是设计中的有效辅助手段。对某相机的长条反射镜组件动力学响应进行了较为深入的研究,借助MSC-patran,用有限元法进行了求解。获得了组件的动力学特性。 相似文献
10.