全文获取类型
收费全文 | 936篇 |
免费 | 25篇 |
国内免费 | 3篇 |
专业分类
化学 | 750篇 |
晶体学 | 14篇 |
力学 | 21篇 |
数学 | 47篇 |
物理学 | 132篇 |
出版年
2023年 | 5篇 |
2021年 | 5篇 |
2020年 | 7篇 |
2019年 | 13篇 |
2018年 | 10篇 |
2017年 | 9篇 |
2016年 | 14篇 |
2015年 | 16篇 |
2014年 | 14篇 |
2013年 | 44篇 |
2012年 | 38篇 |
2011年 | 49篇 |
2010年 | 25篇 |
2009年 | 32篇 |
2008年 | 53篇 |
2007年 | 62篇 |
2006年 | 65篇 |
2005年 | 50篇 |
2004年 | 56篇 |
2003年 | 51篇 |
2002年 | 42篇 |
2001年 | 13篇 |
2000年 | 17篇 |
1999年 | 9篇 |
1998年 | 15篇 |
1997年 | 11篇 |
1996年 | 11篇 |
1995年 | 9篇 |
1994年 | 7篇 |
1993年 | 7篇 |
1992年 | 5篇 |
1991年 | 8篇 |
1990年 | 8篇 |
1989年 | 9篇 |
1988年 | 10篇 |
1986年 | 5篇 |
1985年 | 16篇 |
1984年 | 18篇 |
1982年 | 13篇 |
1981年 | 13篇 |
1980年 | 5篇 |
1979年 | 8篇 |
1978年 | 11篇 |
1977年 | 16篇 |
1976年 | 10篇 |
1974年 | 7篇 |
1970年 | 4篇 |
1968年 | 4篇 |
1967年 | 4篇 |
1965年 | 4篇 |
排序方式: 共有964条查询结果,搜索用时 31 毫秒
941.
942.
Masaru Inage Masahiro Imoto Yoshikazu Kambayashi Shoichi Kusumoto Tetsuo Shiba 《Tetrahedron letters》1980,21(39):3767-3770
Long-chain acyl derivatives of the disaccharide dipeptide, which is a common building unit of bacterial cell walls, were synthesized in order to test their immunostimulating activity. 相似文献
943.
Performance of 0.98-μm InGaAs strained multiquantum-well Fabry-Perot vertical transmission optical amplifiers (MQW FP VTOAs) for optical inter-board connection is analyzed theoretically, and compared with those of GaAs MQW, GaAs bulk, and InGaAsP bulk VTOAs. A low-power operation of about 2 mA and a cascadability of several hundred boards are predicted for an InGaAs strained MQW FP VTOA. 相似文献
944.
945.
A limit of a sequence of fuzzy numbers is defined and its some properties are shown. Based on these concept and properties, an independent sequence of fuzzy random variables is considered and a strong law of large numbers for fuzzy random variables is shown. 相似文献
946.
947.
Pyrazine-2,3-dicarbonitrile ( 1 ) reacts with alkyl radicals to give mono- 3 and di-alkylated pyrazine-2,3-dicarbonitriles 4 . Similarly 1,3-dimethyllumazine ( 2 ) reacts with alkyl radicals to give 7-alkyl-1,3-dimethyllumazines 8 as the major product. The reactivity of alkyl radicals decreases in the order tertiary, secondary, and primary, and 1 is more reactive than 2 in those radical substitution reactions. 相似文献
948.
949.
Yadolah Ganjkhanlou Zdeněk Tišler José Miguel Hidalgo Karel Frolich Jiří Kotera Pavel Čičmanec Roman Bulánek 《Chemical Papers》2018,72(4):937-946
Effect of zirconium presence in the silica framework and content and speciation of vanadium surface oxo-complexes on the catalytic behavior of VOx/Zr–SBA-15 catalysts in oxidative dehydrogenation of ethanol was investigated. Experimental results bring evidence of successful incorporation of zirconium into ordered mesoporous silica framework with the preservation of ordered mesoporosity by hydrothermal template base synthesis method. The presence of zirconium in the SBA-15 framework increases reducibility of vanadium species and acidity of the catalysts. It is reflected in higher activity of vanadium species expressed as turn-over frequency (e.g., TOF of 20 h?1 for 5%VOx/Zr–SBA-15 sample in comparison with TOF of 12 h?1 for 5%VOx/SBA-15 sample) and also in significant decrease of selectivity to acetaldehyde (65% in comparison with 90% for mentioned samples) followed by increase in selectivity to ethylene (25% in comparison with 5%). This change in distribution of reaction products is related to stronger acidity character of surface OH groups and inhibition effect of formed water vapours on the oxidative dehydrogenation products (acetaldehyde). Catalytic data also reveal that oligomeric/polymeric tetrahedrally coordinated vanadium species exhibit higher activity in ethanol oxidative dehydrogenation than monomeric complexes. In addition, comparison of the catalytic performance of VOx/Zr–SBA-15 catalysts with VOx/SBA-15 catalysts showed that catalytic properties of VOx/Zr–SBA-15 catalysts can be tuned by incorporation of controlled amount of zirconium into silica framework. 相似文献
950.
Ryu Hashimoto Dr. Masafumi Minoshima Dr. Junichi Kikuta Shinya Yari Prof. Steven D. Bull Prof. Masaru Ishii Prof. Kazuya Kikuchi 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(47):21182-21186
A rationally designed pH-activatable fluorescent probe (pHocas-RIS) has been used to measure localised pH levels in osteocytic lacunae in bone tissue. Conjugation of the moderate bone-binding drug risedronate to a pH-activatable BODIPY fluorophore enables the probe to penetrate osteocytic lacunae cavities that are embedded deep within the bone matrix. After injection of pHocas-RIS, any osteocytic lacunae caused by bone-resorbing osteocytes cause the probe to fluoresce in vivo, thus allowing imaging by intravital two-photon excitation microscopy. This pH responsive probe enabled the visualization of the bone mineralizing activities of acid producing osteocytes in real time, thus allowing the study of their central role in remodeling the bone-matrix in healthy and disease states. 相似文献