全文获取类型
收费全文 | 115960篇 |
免费 | 17001篇 |
国内免费 | 11570篇 |
专业分类
化学 | 78184篇 |
晶体学 | 1212篇 |
力学 | 7418篇 |
综合类 | 834篇 |
数学 | 14064篇 |
物理学 | 42819篇 |
出版年
2024年 | 364篇 |
2023年 | 2208篇 |
2022年 | 3952篇 |
2021年 | 4197篇 |
2020年 | 4348篇 |
2019年 | 4154篇 |
2018年 | 3711篇 |
2017年 | 3459篇 |
2016年 | 5166篇 |
2015年 | 5282篇 |
2014年 | 6301篇 |
2013年 | 8258篇 |
2012年 | 9957篇 |
2011年 | 10123篇 |
2010年 | 6956篇 |
2009年 | 6717篇 |
2008年 | 7083篇 |
2007年 | 6389篇 |
2006年 | 5912篇 |
2005年 | 5096篇 |
2004年 | 4007篇 |
2003年 | 3115篇 |
2002年 | 2825篇 |
2001年 | 2418篇 |
2000年 | 2186篇 |
1999年 | 2465篇 |
1998年 | 2069篇 |
1997年 | 1889篇 |
1996年 | 1947篇 |
1995年 | 1740篇 |
1994年 | 1555篇 |
1993年 | 1327篇 |
1992年 | 1150篇 |
1991年 | 1025篇 |
1990年 | 858篇 |
1989年 | 704篇 |
1988年 | 528篇 |
1987年 | 493篇 |
1986年 | 447篇 |
1985年 | 423篇 |
1984年 | 281篇 |
1983年 | 265篇 |
1982年 | 194篇 |
1981年 | 149篇 |
1980年 | 107篇 |
1979年 | 67篇 |
1977年 | 69篇 |
1976年 | 70篇 |
1975年 | 77篇 |
1973年 | 73篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
82.
By constructing close-one-cochain density Ω^12n in the gauge group space we get the Wess-Zumino-Witten (WZW) effective Lagrangian on high-dimensional noncommutative space.Especially consistent anomalies derived from this WZW effective action in noncommutative four-dimensional space coincide with those obtained by L.Bonora etc.(het-th/0002210). 相似文献
83.
84.
本文以fp 同伦方法为工具,借助于一些适当的变换,研究有序的(B)空间中的集值映象方程的多正解问题;在文中的有关工作中,还使用了集值映象的拟导数的某些性质. 相似文献
86.
M.-K. Chen 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,21(1):13-18
We examine the influence of relativistic and QED effects on the existence of the 1,3P
o
H- resonances between n
= 2 and 3 hydrogen thresholds, the relativistic and QED corrections and the coupling effects between the high singlet and triplet
states are considered as first-order perturbations. We firstly obtain accurate non-relativistic resonant energies and widths
of fifteen 1P
o
resonances, and fifteen 3P
o
resonances. The fifteen 1P
o
resonances are classified to be
3
(2, 0)
-
n
( 4 ?
n
? 12) and
3
(1, 1)
+
n
( 3 ?
n
? 8). The fifteen 3P
o
resonances are classified to be
3
(2, 0)
+
n
( 3 ?
n
? 12) and
3
(1, 1)
-
n
( 4 ?
n
? 8). We found there exist six Feshbach resonances for
3
(2, 0)
-
n
(1P
o
) series, four Feshbach resonances for
3
(1, 1)
+
n
(1P
o
) series, seven Feshbach resonances for
3
(2, 0)
+
n
(3P
o
) series, and three Feshbach resonances for
3
(1, 1)
-
n
(1P
o
) series.
Received 22 February 2002 Published online 24 September 2002 相似文献
87.
88.
In theory, both polarity and steric hindrance are basic factors which affect molecular interactions. To investigate the optical properties and steric structures of chiral compounds having different chiral moieties which affect the wavelength of light reflection in liquid crystal (LC) cells, a series of novel chiral compounds and azobenzene derivatives were synthesized. The liquid crystalline phases of the compounds were identified using small angle X-ray diffraction, differential scanning calorimetry and polarizing optical microscopy. Cholesteric LC cells with various synthesized chiral dopants which selectively reflect visible light were first prepared, the photochemical switching behaviour of colours was then investigated, with special reference to the change in transmittance in cholesteric LC cells containing an azobenzene derivative as a photoisomerizable guest molecule. Reversible isomerization of azobenzene molecules occurred in the cholesteric systems, resulting in a depression of TChI and a shift of the selectively reflected wavelength. We discuss the photochemically driven change in the helical pitch of the cholesteric LCs with respect to structural effects involving the chiral moieties. Molecular interactions caused by the added dopants, reliability and stability of the photoisomerization, and UV irradiation effects on the cholesteric LC cells were also investigated. A real image was recorded through a mask on a cholesteric LC cell fabricated in this investigation. 相似文献
89.
Browder-Petryshyn 型的严格伪压缩映射的粘滞迭代逼近方法 总被引:1,自引:0,他引:1
主要研究Browder-Petryshyn型的严格伪压缩映射的粘滞迭代逼近过程,证明了Browder-Petryshyn型的严格伪压缩映射的不动点集F(T)是闭凸集.在q-一致光滑且一致凸的Banach空间中,对于严格伪压缩映射T,利用徐洪坤在2004年引进的粘滞迭代得到的序列弱收敛于T的某个不动点.同时证明了Hilbert空间中Browder-Petryshyn型的严格伪压缩映射的相应迭代序列强收敛到T的某个不动点,其结果推广与改进了徐洪坤2004年的相应结果. 相似文献