全文获取类型
收费全文 | 67505篇 |
免费 | 10006篇 |
国内免费 | 8615篇 |
专业分类
化学 | 48451篇 |
晶体学 | 833篇 |
力学 | 3790篇 |
综合类 | 730篇 |
数学 | 8084篇 |
物理学 | 24238篇 |
出版年
2024年 | 170篇 |
2023年 | 1055篇 |
2022年 | 1933篇 |
2021年 | 2146篇 |
2020年 | 2284篇 |
2019年 | 2265篇 |
2018年 | 1977篇 |
2017年 | 1892篇 |
2016年 | 2882篇 |
2015年 | 2989篇 |
2014年 | 3708篇 |
2013年 | 4806篇 |
2012年 | 5688篇 |
2011年 | 5838篇 |
2010年 | 4233篇 |
2009年 | 4117篇 |
2008年 | 4615篇 |
2007年 | 4161篇 |
2006年 | 3925篇 |
2005年 | 3322篇 |
2004年 | 2837篇 |
2003年 | 2305篇 |
2002年 | 2437篇 |
2001年 | 1926篇 |
2000年 | 1646篇 |
1999年 | 1525篇 |
1998年 | 1133篇 |
1997年 | 1033篇 |
1996年 | 1044篇 |
1995年 | 881篇 |
1994年 | 802篇 |
1993年 | 702篇 |
1992年 | 656篇 |
1991年 | 518篇 |
1990年 | 462篇 |
1989年 | 360篇 |
1988年 | 297篇 |
1987年 | 266篇 |
1986年 | 192篇 |
1985年 | 209篇 |
1984年 | 165篇 |
1983年 | 138篇 |
1982年 | 96篇 |
1981年 | 75篇 |
1980年 | 66篇 |
1979年 | 41篇 |
1978年 | 51篇 |
1976年 | 39篇 |
1975年 | 37篇 |
1974年 | 30篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
5,6-Dihydro-OSW-1 (1) was synthesized following our previous procedure for the total synthesis of OSW-1. This compound demonstrated slightly stronger potency than that of OSW-1 against the growth of cancer cells. 相似文献
82.
Gui Hong YAN Da XING* Shi Ci TAN Institute of Laser Life Science South China Normal University Guangzhou 《中国化学快报》2004,15(1):101-104
Electrochemiluminescence (ECL), like other chemiluminescence technique, offers high signal-to-noise ratio. Furthermore, it has the advantage over other chemiluminescence techniques of being initiated by a voltage potential. Thus, it provides a better-controlled luminescence. This technique has been used in measuring many kinds of organic and inorganic matters, and analyzing many kinds of antigen, antibody and hapten, such as carcinoembryonic antigen and alpha-fetoprotein, etc1-6. The ele… 相似文献
83.
DongXiangLI WanGuoHOU ShuPingLI MingTuHAO GaoYongZHANG 《中国化学快报》2004,15(2):224-227
The relation of the isoelectric point (IEP) and the point of zero net charge (PZNC) of the hydrotalcite-like compounds was discussed. It was found that the IEP does not equal to the PZNC and the IEP is higher than the PZNC. The structural positive charges existing in the HTlc,which cause the difference between the IEP and the PZNC. The effects of the structural positive charges of the HTlc on its IEP and PZNC are the same as the specific adsorption of metal cations. 相似文献
84.
Zhong Hong YAN Chun Hao YANG Xi Han WU Yu Yuan XIEDivision of Chemistry Shanghai Second Medical University Shanghai Sate Key Laboratory of Drug Research Shanghai Institute of Materia Medica Shanghai Institutesfor Biological Sciences Shanghai 《中国化学快报》2004,(4)
The first and facile synthesis of (±)syringaresinol was described. 相似文献
85.
Ming Zhao WANG Guan Liang CAI Ling XIA Jun Jian YAO Hong Yan CHEN Zhao Xing MENG Bo Li LIUDepartment of Chemistry Beijing Normal University Beijing Chemical Defense Institute PLA Beijing 《中国化学快报》2004,15(4):495-497
The crystal structures of two potential tumor imaging agents and therapeutic agents -copper(Ⅱ) complexes with salicylidene-tyrosinato Schiff base and nitrogen-donor chelating Lewis base, [Cu(sal-tyr)(bipy)] 1 and [Cu(sal-tyr)(phen)]2CH3OH 2 are presented. Our work is helpful to get deep understanding of novel 64Cu tumor imaging agents and therapeutic agents. 相似文献
86.
Yoshimi Egawa Mariko Hagita Ken-ichi Kawarabayashi Hong Wang 《Discrete Mathematics》2003,270(1-3):115-125
Let d, k and n be three integers with k3, d4k−1 and n3k. We show that if d(x)+d(y)d for each pair of nonadjacent vertices x and y of a graph G of order n, then G contains k vertex-disjoint cycles converting at least min{d,n} vertices of G. 相似文献
87.
多小波子空间上的单小波表示 总被引:1,自引:0,他引:1
本文在较弱的条件下,建立了2重多小波子空间与单小波子空间的关系.即由2重多小波构造出单小波.一方面,这种单小波的平移伸缩与2重多小波的平移伸缩生成的子空间是完全相同的;另一方面,它具有插值性.因此通过构造出的单小波建立了多小波子空间上的Shannon型采样定理. 相似文献
88.
Jensen and Toft 8 conjectured that every 2‐edge‐connected graph without a K5‐minor has a nowhere zero 4‐flow. Walton and Welsh 19 proved that if a coloopless regular matroid M does not have a minor in {M(K3,3), M*(K5)}, then M admits a nowhere zero 4‐flow. In this note, we prove that if a coloopless regular matroid M does not have a minor in {M(K5), M*(K5)}, then M admits a nowhere zero 4‐flow. Our result implies the Jensen and Toft conjecture. © 2005 Wiley Periodicals, Inc. J Graph Theory 相似文献
89.
QiangWU DaChunYANG 《数学学报(英文版)》2005,21(1):81-94
In this paper, two classes of closely related multilinear singular and fractional integrals,which include the commutators as special cases, are studied and their boundedness on Herz type spaces is discussed. In fact, it is proved that these operators are actually not bounded in certain extreme cases. 相似文献
90.
In this article we have studied the nonlinear interaction between ellipticity and dissipation in a set of model equations (1.1) and established the relation between this interaction and chaos. In addition to theoretical investigations, extensive numerical simulations with these equations have been made, and different routes to chaos have been found. The numerical studies have revealed the chaotic nature of the solutions. 相似文献