全文获取类型
收费全文 | 15513篇 |
免费 | 2653篇 |
国内免费 | 3329篇 |
专业分类
化学 | 11390篇 |
晶体学 | 344篇 |
力学 | 974篇 |
综合类 | 417篇 |
数学 | 2040篇 |
物理学 | 6330篇 |
出版年
2024年 | 45篇 |
2023年 | 229篇 |
2022年 | 503篇 |
2021年 | 510篇 |
2020年 | 541篇 |
2019年 | 536篇 |
2018年 | 498篇 |
2017年 | 539篇 |
2016年 | 654篇 |
2015年 | 731篇 |
2014年 | 905篇 |
2013年 | 1185篇 |
2012年 | 1281篇 |
2011年 | 1351篇 |
2010年 | 1111篇 |
2009年 | 1078篇 |
2008年 | 1237篇 |
2007年 | 1060篇 |
2006年 | 943篇 |
2005年 | 866篇 |
2004年 | 768篇 |
2003年 | 611篇 |
2002年 | 700篇 |
2001年 | 625篇 |
2000年 | 472篇 |
1999年 | 440篇 |
1998年 | 242篇 |
1997年 | 192篇 |
1996年 | 214篇 |
1995年 | 169篇 |
1994年 | 164篇 |
1993年 | 175篇 |
1992年 | 134篇 |
1991年 | 111篇 |
1990年 | 99篇 |
1989年 | 91篇 |
1988年 | 70篇 |
1987年 | 62篇 |
1986年 | 54篇 |
1985年 | 49篇 |
1984年 | 34篇 |
1983年 | 29篇 |
1982年 | 24篇 |
1981年 | 24篇 |
1980年 | 15篇 |
1979年 | 10篇 |
1959年 | 14篇 |
1958年 | 11篇 |
1957年 | 15篇 |
1956年 | 10篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
121.
AO Sheng-Mei YAN Jia-Ren 《理论物理通讯》2007,47(1):15-18
Three types of expression in the dark-soliton perturbation theory based on squared Jost solutions are invesgigaged in ghis paper. It is shown that there are three formally different results about the effects of perturbagion on a dark soliton, and it is proved by means of a transformation between two integral variables that they are essentially equivalent. 相似文献
122.
Seed of Litchi chinensis Sonn. is a traditional Chinese medicine, having curative effects on gastric disease, diabetes,and relieving pain.[1] Two new compounds 4-O-p-coumaroylquinic acid butyl ester (1) and 3-O-p-coumaroylquinic acid butyl ester (2), along with five known compounds: 5-O-p-coumaroylquinic acid butyl ester (3),[2] 3-O-p-coumaroylquinic acid methyl ester (4),[3] n-butyl-1-β-D-fructopyranoside (5),[4] D-1-O-methylmyo-inositol (6)[5] and 1H-imidazole-2,3-dihydro-2-oxo-4-carboxylic acid methyl ester (7)[5] were isolated and purified from the ethanol extracts of the seed of L.chinensis Sonn. Their structures, shown in Figure 1, were elucidated by ESI-MS, 1H NMR and 13C NMR, including 2DNMR spectroscopy. 相似文献
123.
设k是一个正整数,G是一个顶点数为|G|=4k的图. 假设σ\-2(G)≥4k-1, 则G有一个支撑子图含k-1个4圈和一条顶点数为4的路,使得所有这些圈和路都是相互独立的. 设G=(V\-1,V \-2;E)是一个二分图使得|V\-1|=|V\-2|=2k. 如果对G中每一对满足x∈V\-1和y∈V\-2的不 相邻的顶点x和y 都有d(x)+d(y)≥2k+1, 则G包含k-1个相互独立的4圈和一条顶点数为4的路,使得所有这些圈和路都是相互独立的,并且此度条件是最好的. 相似文献
124.
Do Young Kim Ji Sim Jung Young Rae Jang Kun Ho Yoo Jin Jang 《Physica E: Low-dimensional Systems and Nanostructures》2003,16(3-4):400
We studied the growth of nanocrystalline silicon (nc-Si) thin film exhibiting a strong room temperature photoluminescence (PL) at 1.81–2.003 eV. The amorphous silicon was crystallized by Ni silicide mediated crystallization (Ni SMC) and then Secco-etched to exhibit the PL. The PL peak energy and intensity increase with increasing the metal density on the a-Si because of the reduction in the grain size down to 2 nm. The photoluminescence energy and peak intensity depend strongly on the Secco etch time because the grain size is reduced by etching the grain boundaries. 相似文献
125.
分别用连续波1.319μm激光和10.6μm激光辐照PC型HgCdTe红外探测器时,得到了不同辐照光功率密度下,探测器输出的一系列实验结果。给出了在波长为1.319μm的波段内激光辐照下PC型HgCdTe探测器的饱和阈值;用波长为10.6μm的波段外CO2激光辐照探测器时,发现了一些与波段内激光辐照探测器时大不相同的实验现象;对实验结果进行了分析。简要总结了PC型HgCdTe探测器对于波段内和波段外激光辐照的响应机制。 相似文献
126.
1-Propyl-3-methylimidazolium chloride ([C3MIm]Cl) ionic liquid and sulfamic acid (NH2SO3H), as a synergetic catalytic medium, were used for the transesterification of acetoacetate with alcohols of different structures. It shows the good ability for the chemoselective transesterificatin of β-ketoesters and maintains its catalytic activity in the reuse. 相似文献
127.
DING Xuantong YANG Qingwei YAN Long wen LIU Yi HUANG Yuan LIU Zetian HONG Wenyu SHI Peilan 《核工业西南物理研究院年报(英文版)》2004,(1):1-4
The main mission the HL-2A tokamak is of the experiments on to explore the divertor physics and to investigate the plasma confinement, transport and instabilities with high power auxiliary heating and advanced fuelling, it is necessary to develop more new diagnostics and increase the spatial and temporal resolutions of the measurements for exist system. Up to now, about 30 diagnostic systems have been moved from HL-1M to HL-2A tokamak. Other 10 diagnostic systems are being designed and installed on the device. In developed in last 2 years, will be presented. 相似文献
128.
CHEN Yong YAN Zhen-Ya 《理论物理通讯》2005,44(5):789-792
Recently some (1+1)-dimensional nonlinear wave equations with linearly dispersive terms were shown to possess compacton-like and solitary pattern-like solutions. In this paper, with the aid of Maple, new solutions of (2+1)- dimensional generalization of mKdV equation, which is of only linearly dispersive terms, are investigated using three new transformations. As a consequence, it is shown that this (2+1)-dimensional equation also possesses new compacton-like solutions and solitary pattern-like solutions. 相似文献
129.
130.