全文获取类型
收费全文 | 8148篇 |
免费 | 2121篇 |
国内免费 | 3171篇 |
专业分类
化学 | 4904篇 |
晶体学 | 397篇 |
力学 | 1205篇 |
综合类 | 217篇 |
数学 | 417篇 |
物理学 | 6300篇 |
出版年
2024年 | 92篇 |
2023年 | 277篇 |
2022年 | 373篇 |
2021年 | 327篇 |
2020年 | 294篇 |
2019年 | 323篇 |
2018年 | 200篇 |
2017年 | 299篇 |
2016年 | 357篇 |
2015年 | 372篇 |
2014年 | 736篇 |
2013年 | 554篇 |
2012年 | 591篇 |
2011年 | 657篇 |
2010年 | 589篇 |
2009年 | 610篇 |
2008年 | 703篇 |
2007年 | 592篇 |
2006年 | 579篇 |
2005年 | 542篇 |
2004年 | 561篇 |
2003年 | 473篇 |
2002年 | 398篇 |
2001年 | 378篇 |
2000年 | 359篇 |
1999年 | 272篇 |
1998年 | 242篇 |
1997年 | 271篇 |
1996年 | 259篇 |
1995年 | 194篇 |
1994年 | 193篇 |
1993年 | 125篇 |
1992年 | 157篇 |
1991年 | 148篇 |
1990年 | 139篇 |
1989年 | 101篇 |
1988年 | 32篇 |
1987年 | 36篇 |
1986年 | 12篇 |
1985年 | 7篇 |
1984年 | 3篇 |
1983年 | 7篇 |
1982年 | 3篇 |
1979年 | 2篇 |
1951年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
花丝内插物强化竖直管内凝结换热的实验研究 总被引:1,自引:1,他引:0
1前言大空隙率多孔体管内插物-绕花丝内插物,被认为是强化管内凝结换热的最有效途径之一[1].但以往的研究,由于实验雷诺数范围较小,蒸汽速度较低,要正确全面评价其性能尚显不够。本文在原有工作的基础上,进一步完善了实验系统,改进了测试手段,扩大了实验雷诺数范围,并测试了其阻力性能,对花丝内插物强化管内凝结换热进行了较深入全面的实验研究,以全面评价花丝内插物对管内凝结换热的强化效果。2实验系统本文实验系统如图1所示。实验段是一个竖直套管冷凝器,如图2所示.本试验研究蒸汽完全凝结时的传热。凝结水流量采用容积法计… 相似文献
32.
Study on the in—plane electrical resistivity and thermoelectric power in single crystals of La2—xBaxCuO4
下载免费PDF全文
![点击此处可从《中国物理》网站下载免费的PDF全文](/ch/ext_images/free.gif)
The in-plane electrical resistivity and thermoelectric power have been measured on single crystals of La2-xBaxCuO4 at around x=0.125. The room temperature resistivity and thermopower have their maximum values at x=0.125, indicating that the carrier concentration is the minimum and the carriers are most strongly localized at x=0.125. The observed semiconductor-like behaviour can be well described by the weak-localized quasi-two-dimensional state. The steep rise in electric resistivity of the sample at x=0.125 below 70K is attributed to the formation of static stripe-order of holes and spins, which are pinned by the low-temperature tetragonal (LTT) structure, as discovered in La1.48Nd0.4Sr0.12CuO4. The temperature dependence of electric resistivity below 70K is still well described by the formula ρ∝ lnT. A definite change in the slope of thermopower is observed at the low-temperature orthorhombic-LTT structural phase transition temperature. The origin of the 1/8 anomaly is discussed in the text. 相似文献
33.
34.
35.
Thermal Rate Constants of the N(^4S)+O2(X^3∑g^-) → NO(X^2Ⅱ) +O(^3P) Reaction on the ^2A′ Potential Energy Surface
下载免费PDF全文
![点击此处可从《中国物理快报》网站下载免费的PDF全文](/ch/ext_images/free.gif)
A quasiclassical trajectory study with the sixth-order explicit symplectic algorithm for the N(^4S)+O2(X^3∑g^-) → NO(X^2Ⅱ) +O(^3P) reaction has been reported by employing a new ground potential energy surface. We have discussed the influence of the relative translational energy, the vibrational and rotational levels of O2 molecules on the total reaction cross section. Thermal rate constants at temperatures 300, 600, and 1000 K determined in this work for the reaction are 4.4 × 10^7, 1.8 × 10^10, and 3.1 × 10^11 cm^3mol^-1s^-1, respectively. It is found that they are in better agreement with the experimental data than previous theoretical values. 相似文献
36.
Total Dose Radiation Tolerance of Phase Change Memory Cell with GeSbTe Alloy 总被引:1,自引:0,他引:1
下载免费PDF全文
![点击此处可从《中国物理快报》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Phase change memory (PCM) cell array is fabricated by a standard complementary metal-oxide-semiconductor process and the subsequent special fabrication technique. A chalcogenide Ge2Sb2Te5 film in thickness 50hm deposited by rf magnetron sputtering is used as storage medium for the PCM cell. Large snap-back effect is observed in current-voltage characteristics, indicating the phase transition from an amorphous state (higher resistance state) to the crystalline state (lower resistance state). The resistance of amorphous state is two orders of magnitude larger than that of the crystalline state from the resistance measurement, and the threshold current needed for phase transition of our fabricated PCM cell array is very low (only several μA). An x-ray total dose radiation test is carried out on the PCM cell array and the results show that this kind of PCM cell has excellent total dose radiation tolerance with total dose up to 2 ×10^6 rad(Si), which makes it attractive for space-based applications. 相似文献
37.
38.
39.
40.
Application of Electron-Shelving Detection via 423 nm Transition in Calcium-Beam Optical Frequency Standard
下载免费PDF全文
![点击此处可从《中国物理快报》网站下载免费的PDF全文](/ch/ext_images/free.gif)
A new scheme of small compact optical frequency standard based on thermal calcium beam with application of 423 nm shelving detection and sharp-angle velocity selection detection is proposed. Combining these presented techniques, we conclude that a small compact optical frequency standard based on thermal calcium beam will outperform the commercial caesium-beam microwave dock, like the 5071 Cs clock (from Hp to Agilent, now Symmetricom company), both in accuracy and stability. 相似文献