全文获取类型
收费全文 | 1223篇 |
免费 | 21篇 |
专业分类
化学 | 876篇 |
晶体学 | 8篇 |
力学 | 7篇 |
数学 | 83篇 |
物理学 | 270篇 |
出版年
2022年 | 11篇 |
2021年 | 14篇 |
2020年 | 16篇 |
2019年 | 12篇 |
2018年 | 17篇 |
2017年 | 11篇 |
2016年 | 14篇 |
2015年 | 17篇 |
2014年 | 12篇 |
2013年 | 46篇 |
2012年 | 36篇 |
2011年 | 72篇 |
2010年 | 42篇 |
2009年 | 34篇 |
2008年 | 54篇 |
2007年 | 70篇 |
2006年 | 54篇 |
2005年 | 41篇 |
2004年 | 47篇 |
2003年 | 55篇 |
2002年 | 38篇 |
2001年 | 33篇 |
2000年 | 21篇 |
1999年 | 20篇 |
1997年 | 29篇 |
1996年 | 17篇 |
1995年 | 8篇 |
1994年 | 16篇 |
1993年 | 25篇 |
1992年 | 24篇 |
1991年 | 15篇 |
1990年 | 23篇 |
1989年 | 12篇 |
1988年 | 12篇 |
1987年 | 19篇 |
1986年 | 14篇 |
1985年 | 30篇 |
1984年 | 19篇 |
1983年 | 12篇 |
1982年 | 12篇 |
1981年 | 8篇 |
1980年 | 26篇 |
1979年 | 25篇 |
1978年 | 18篇 |
1977年 | 11篇 |
1976年 | 14篇 |
1975年 | 8篇 |
1974年 | 11篇 |
1973年 | 8篇 |
1972年 | 9篇 |
排序方式: 共有1244条查询结果,搜索用时 17 毫秒
971.
Masaya Kakimoto Hideki Ueno Hiroyuki Kojima Yoichi Yamaguchi Akira Nishimura 《Journal of polymer science. Part A, Polymer chemistry》1996,34(13):2753-2758
The doping effects on optical and electrical properties of polysilanes were investigated by in-situ measurement. When polysilanes bearing a p-N,N-dialkylaminophenyl substituent were doped with iodine vapor, drastic spectral changes were observed. The evolved visible absorption up to 700 nm was found to be strong and stable compared to that of iodine-doped polysilanes such as poly(methylphenylsilane). On the basis of the studies concerning iodine doping of the related p-N,N-dimethylaminophenyl-substituted silane and disilane, and also theoretical calculations, this new absorption can be best interpreted by the result of charge transfer consisting of the strong interaction between iodine and dialkylamino substituents in the polysilanes. © 1996 John Wiley & Sons, Inc. 相似文献
972.
973.
Y. Nabekawa T. Togashi T. Sekikawa S. Watanabe S. Konno T. Kojima S. Fujikawa K. Yasui 《Applied physics. B, Lasers and optics》2000,70(7):S171-S179
We have developed an all-solid-state Ti:sapphire laser system, which produces 22-fs, 0.2-TW pulses at 5-kHz repetition rate. An average power of 22.2 W is the highest ever obtained in ultrashort laser sources. The serious thermal lensing due to high power pumping in a small area of Ti:sapphire crystal is controlled successfully by a stable quasi-cavity with two concave mirrors. The attempt to increase the repetition rate to 10 kHz is also described. 相似文献
974.
975.
976.
Seiya Fukagawa Masahiro Kojima Tatsuhiko Yoshino Shigeki Matsunaga 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(50):18322-18326
Catalytic enantioselective directed methylene C(sp3)?H amidation reactions of 8‐alkylquinolines using a Cp*RhIII/chiral carboxylic acid (CCA) hybrid catalytic system are described. A binaphthyl‐based chiral carboxylic acid efficiently differentiates between the enantiotopic methylene C?H bonds, which leads to the formation of C?N bonds with good enantioselectivity. 相似文献
977.
Dr. Masahiro Ikeshita Sho Furukawa Takahiro Ishikawa Kana Matsudaira Prof.Dr. Yoshitane Imai Prof.Dr. Takashi Tsuno 《ChemistryOpen》2022,11(4)
Invited for this month''s cover picture are the groups of Masahiro Ikeshita and Takashi Tsuno at Nihon University and Yoshitane Imai at Kindai University (Japan). The cover picture shows the comparison of circularly polarized luminescence (CPL) properties of square planar platinum(II) complexes with different coordination geometry. Computational studies have been carried out to investigate these structure‐dependencies, and revealed that the distortion of the coordination geometry results into an enhancement the chiroptical responses of these compounds. Read the full text of their Research Article at 10.1002/open.202100277. “… How does the stereochemistry of transition metal complexes affect their photophysical properties…” Find out more about the story behind the front cover research at 10.1002/open.202100277. 相似文献
978.
979.
Yugo Kuriki Takafusa Yoshioka Mako Kamiya Toru Komatsu Hiroyuki Takamaru Kyohhei Fujita Hirohisa Iwaki Aika Nanjo Yuki Akagi Kohei Takeshita Haruaki Hino Rumi Hino Ryosuke Kojima Tasuku Ueno Kenjiro Hanaoka Seiichiro Abe Yutaka Saito Jun Nakajima Yasuteru Urano 《Chemical science》2022,13(16):4474
Fluorescent probes that can selectively detect tumour lesions have great potential for fluorescence imaging-guided surgery. Here, we established a library-based approach for efficient screening of probes for tumour-selective imaging based on discovery of biomarker enzymes. We constructed a combinatorial fluorescent probe library for aminopeptidases and proteases, which is composed of 380 probes with various substrate moieties. Using this probe library, we performed lysate-based in vitro screening and/or direct imaging-based ex vivo screening of freshly resected clinical specimens from lung or gastric cancer patients, and found promising probes for tumour-selective visualization. Further, we identified two target enzymes as novel biomarker enzymes for discriminating between tumour and non-tumour tissues. This library-based approach is expected to be an efficient tool to develop tumour-imaging probes and to discover new biomarker enzyme activities for various tumours and other diseases.Efficient methodology to develop tumor-imaging fluorescent probes based on screening with our newly constructed probe library for aminopeptidase/protease (380 probes) and clinical samples has been established. 相似文献
980.
We investigated the enhancing effect of three alkyl-2-pyrrolidones on transdermal penetration of phenolsulfonphthalein (phenol red) and indomethacin from an aqueous vehicle by using an in vitro technique with excised rat skin. The enhancers included 1-methyl- (I), 1-hexyl- (II) and 1-lauryl-2-pyrrolidone (III). These derivatives effectively enhanced the penetration and skin accumulation of phenol red and indomethacin. Lipophilic enhancers such as II and III showed particularly high enhancing effects. The penetration profiles of phenol red and indomethacin showed a lag phase followed by a linear increase. Compounds II and III showed long lag times. The enhancer penetration was also determined. Compounds I and II showed a slight penetration. Compound III showed little penetration but high skin accumulation. 相似文献