全文获取类型
收费全文 | 94972篇 |
免费 | 4281篇 |
国内免费 | 4831篇 |
专业分类
化学 | 20866篇 |
晶体学 | 393篇 |
力学 | 3809篇 |
综合类 | 502篇 |
数学 | 10469篇 |
物理学 | 19750篇 |
综合类 | 48295篇 |
出版年
2024年 | 223篇 |
2023年 | 754篇 |
2022年 | 1591篇 |
2021年 | 1625篇 |
2020年 | 1651篇 |
2019年 | 1607篇 |
2018年 | 1422篇 |
2017年 | 1670篇 |
2016年 | 1874篇 |
2015年 | 2153篇 |
2014年 | 4085篇 |
2013年 | 4827篇 |
2012年 | 4808篇 |
2011年 | 5284篇 |
2010年 | 4184篇 |
2009年 | 5504篇 |
2008年 | 5733篇 |
2007年 | 6834篇 |
2006年 | 6057篇 |
2005年 | 5035篇 |
2004年 | 4384篇 |
2003年 | 4422篇 |
2002年 | 4608篇 |
2001年 | 3589篇 |
2000年 | 3139篇 |
1999年 | 2553篇 |
1998年 | 2225篇 |
1997年 | 1540篇 |
1996年 | 1442篇 |
1995年 | 1262篇 |
1994年 | 1212篇 |
1993年 | 936篇 |
1992年 | 980篇 |
1991年 | 740篇 |
1990年 | 655篇 |
1989年 | 564篇 |
1988年 | 459篇 |
1987年 | 387篇 |
1986年 | 300篇 |
1985年 | 244篇 |
1984年 | 233篇 |
1983年 | 140篇 |
1982年 | 189篇 |
1981年 | 181篇 |
1980年 | 121篇 |
1979年 | 149篇 |
1978年 | 126篇 |
1977年 | 119篇 |
1976年 | 75篇 |
1973年 | 57篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
151.
M. Brando N. Büttgen V. Fritsch J. Hemberger H. Kaps H.-A. Krug von Nidda M. Nicklas K. Pucher W. Trinkl A. Loidl E.W. Scheidt M. Klemm S. Horn 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,25(3):289-298
We present susceptibility, microwave resistivity, NMR and heat-capacity results for Li1-xZnx(V1-yTiy)2O4 with 0 ?
x
? 0.3 and 0 ?
y
? 0.3. For all doping levels the susceptibility curves can be fitted with a Curie-Weiss law. The paramagnetic Curie-Weiss temperatures
remain negative with an average value close to that of the pure compound Θ≈ - 36 K. Spin-glass anomalies are observed in the susceptibility, heat-capacity and NMR measurements for both type of dopants.
From the temperature dependence of the spin-lattice relaxation rate we found critical-dynamic behavior in the Zn doped compounds
at the freezing temperatures. For the Ti-doped samples two successive freezing transitions into disordered low-temperature
states can be detected. The temperature dependence of the heat capacity for Zn-doped compounds does not resemble that of canonical
spin glasses and only a small fraction of the total vanadium entropy is frozen at the spin-glass transitions. For pure LiV2O4 the spin-glass transition is completely suppressed. The temperature dependence of the heat capacity for LiV2O4 can be described using a nuclear Schottky contribution and the non-Fermi liquid model, appropriate for a system close to
a spin-glass quantum critical point. Finally an (
x
/
y
,
T
)-phase diagram for the low-doping regime is presented.
Received 16 March 2001 and Received in final form 30 October 2001 相似文献
152.
G. Tiana M.H. Jensen K. Sneppen 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,29(1):135-140
A feedback mechanism that involves the proteins p53 and mdm2, induces cell death as a controlled response to severe DNA damage.
A minimal model for this mechanism demonstrates that the response may be dynamic and connected with the time needed to translate
the mdm2 protein. The response takes place if the dissociation constant k between p53 and mdm2 varies from its normal value. Although it is widely believed that it is an increase in k that triggers the response, we show that the experimental behaviour is better described by a decrease in the dissociation
constant. The response is quite robust upon changes in the parameters of the system, as required by any control mechanism,
except for few weak points, which could be connected with the onset of cancer.
Received 8 May 2002 / Received in final form 9 July 2002 Published online 17 September 2002 相似文献
153.
154.
155.
Patrick Dehornoy 《Algebra Universalis》2002,48(2):223-248
We solve the word problem of the identity x(yz) = (xy)(yz) by investigating a certain group describing the geometry of that identity. We also construct a concrete realization of the
one-generated free algebra relative to the above identity.
Received March 23, 2001; accepted in final form July 6, 2002. 相似文献
156.
157.
A convective flow CO laser composed of polytetrafluoroethylene discharge tubes, nickel–chromium steel components, a cupric heat exchanger and other components is described. Operating in liquid nitrogen condition, output power of 60 W has been obtained from a non-selective cavity. 相似文献
158.
A. Khrennikov 《Annalen der Physik》2003,12(10):575-585
We study the probabilistic consequences of the choice of the basic number field in the quantum formalism. We demonstrate that by choosing a number field for a linear space representation of quantum model it is possible to describe various interference phenomena. We analyse interference of probabilistic alternatives induced by real, complex, hyperbolic (Clifford) and p‐adic representations. 相似文献
159.
平行机半在线排序问题研究(Ⅰ) 总被引:15,自引:1,他引:14
对半在线平行机排序问题的研究进展作了详细综述和进一步探讨。文章给出半在线排序问题的背景、定义、分类和求解。介绍它们定义和在不同机器环境和目标函数下半在线排序问题分类,以及第一类半在线模型的近似算法的设计及其竞争比分析。 相似文献
160.
针对傅里叶-贝塞尔变换(FBT)难以估计和有效分离多分量LFM信号的问题,提出了一种k分辨-FB(k-FB)级数展开结合dechirp的信号分离与估计算法。在FB级数的基础上引入k分辨参数,通过理论推导,得出了信号频率与级数的关系,证明了参数估计精度与k取值正相关。通过解线频调和k-FB级数计算,实现了信号分离重构和参数估计。在不同信噪比、信号功率比和k分辨条件下对信号的分离精度进行了仿真研究,并与基于分数阶傅里叶变换(FrFT)的方法进行了对比。仿真结果验证了算法的有效性。 相似文献