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491.
The WXYZA'B'C' ring system ( 1) of maitotoxin (MTX) was synthesized in a convergent manner via successive coupling of the W, Z, and C' ring fragments through construction of the XY and A'B' ring systems. The synthetic segment 1 blocked the hemolytic activity elicited by MTX. 相似文献
492.
An acid and base stable hydroxytetrachlorodiphenylmethyl (HTPM) linker is developed for polymer-supported organic synthesis. The linkers reported here are utilized for loading carboxylic acids, amines, alcohols, and phenols, and are stable to Br?nsted and Lewis acids, Br?nsted bases, and a wide variety of nucleophiles. However, the HTPM linkers can conveniently be cleaved by the solvolytic displacement reactions with 20% TFA. [structure: see text] 相似文献
493.
Takehiko Nagai Tetsuya Kaneko Zhengxin Liu Ivan Turkevych Michio Kondo 《Journal of Non》2012,358(17):2281-2284
Hydrogenated-amorphous silicon tin alloy (a-SiSn (C:H)) films have been prepared by very high frequency plasma enhanced chemical vapor deposition (VHF-PECVD) technique. We present investigations of the absorption and photoconductivity characteristics of a-SiSn(C:H) thin films as a function of the tin concentration, which could be a pivotal feature for the bottom solar cell development. We demonstrate that the photoconductivity is significantly improved by the film growth under enhanced hydrogen dilution. The results suggest that the hydrogen dilution plays an important role in development of high quality a-SiSn(C:H) photosensitive thin films. 相似文献
494.
495.
Michio Yamada Dr. Mayuko Okamura Satoru Sato Chika I. Someya Naomi Mizorogi Dr. Takahiro Tsuchiya Dr. Takeshi Akasaka Prof. Tatsuhisa Kato Prof. Shigeru Nagase Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(40):10533-10542
The two regioisomers of endohedral pyrrolidinodimetallofullerenes M2@Ih‐C80(CH2)2NTrt (M=La, Ce; Trt=trityl) were synthesized, isolated, and characterized. X‐ray crystallographic analyses of [6,6]‐La2@Ih‐C80(CH2)2NTrt and [6,6]‐Ce2@Ih‐C80(CH2)2NTrt revealed that the encapsulated metal atoms are located at the slantwise positions on the mirror plane that parallels the pyrrolidine ring. Paramagnetic NMR analyses of [6,6]‐ and [5,6]‐Ce2@Ih‐C80(CH2)2NTrt were also carried out to clarify the metal positions. As for the [6,6]‐adduct, the metal positions obtained by paramagnetic NMR analysis agree well with the X‐ray structure. In contrast, paramagnetic NMR analysis of the [5,6]‐adduct showed that the two Ce atoms are collinear with the pyrrolidine ring. We also compared the observed paramagnetic effects of the pyrrolidinodimetallofullerenes with those of other cerium‐encapsulating fullerene derivatives such as bis‐silylated Ce2@Ih‐C80 and a carbene adduct of Ce2@Ih‐C80. We found that the metal positions can be explained by the electrostatic potential maps of the corresponding [6,6]‐ and [5,6]‐adducts of [Ih‐C80(CH2)2NTrt]6?. These findings clearly show that metal positions inside fullerene cages can be controlled by means of the addition positions of the addends. In addition, the radical anions of the pyrrolidinodimetallofullerenes were prepared by bulk controlled‐potential electrolysis and characterized by X‐band EPR spectral study. 相似文献
496.
Conformational Change of Spermidine upon Interaction with Adenosine Triphosphate in Aqueous Solution
Keisuke Maruyoshi Dr. Kaori Nonaka Takeshi Sagane Tetsuo Demura Toshiyuki Yamaguchi Nobuaki Matsumori Dr. Tohru Oishi Prof. Dr. Michio Murata Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(7):1618-1626
A complex rotation : The solution conformation of spermidine (SPD) was elucidated by using diastereospecifically deuterated and 13C‐labeled derivatives to diagnose the orientation of seven conformationally relevant bonds. NMR coupling constants were determined for a complex formed from spermidine and adenosine triphosphate (ATP; see figure).
497.
Weifang Wang Taiko Oda Kazuyo Ukai Henki Rotinsulu Hisayoshi Kobayashi Michio Namikoshi 《Tetrahedron》2009,65(46):9598-9603
Seven new polysulfur alkaloids, lissoclibadins 8 (1)-14 (7), were isolated from an ascidian, Lissoclinum cf. badium, collected in Indonesia. The structures were assigned on the basis of their spectroscopic data and computational modeling study. Lissoclibadin 8 (1) had four identical dopamine-derived units, and this is the first instance of a tetramer. Lissoclibadin 9 (2) was the second example of trimers next to lissoclibadin 1 (8). Lissoclibadins 10 (3)-12 (5) were symmetric dimers, and 13 (6) had a dopamine and ethyl units connected by sulfide and disulfide bonds. Lissoclibadin 14 (7) was a varacin-type monomer. These compounds inhibited the colony formation of Chinese hamster V79 cells and cell proliferation of murine leukemia L1210 cells. 相似文献
498.
Michio Iwaoka Naoki Kimura Daisuke Yosida Toshiya Minezaki 《Journal of computational chemistry》2009,30(13):2039-2055
Molecular simulation by using force field parameters has been widely applied in the fields of peptide and protein research for various purposes. We recently proposed a new all‐atom protein force field, called the SAAP force field, which utilizes single amino acid potentials (SAAPs) as the fundamental elements. In this article, whole sets of the SAAP force field parameters in vacuo, in ether, and in water have been developed by ab initio calculation for all 20 proteinogenic amino acids and applied to Monte Carlo molecular simulation for two short peptides. The side‐chain separation approximation method was employed to obtain the SAAP parameters for the amino acids with a long side chain. Monte Carlo simulation for Met‐enkephalin (CHO‐Tyr‐Gly‐Gly‐Phe‐Met‐NH2) by using the SAAP force field revealed that the conformation in vacuo is mainly controlled by strong electrostatic interactions between the amino acid residues, while the SAAPs and the interamino acid Lennard‐Jones potentials are predominant in water. In ether, the conformation would be determined by the combination of the three components. On the other hand, the SAAP simulation for chignolin (H‐Gly‐Tyr‐Asp‐Pro‐Glu‐Thr‐Gly‐Thr‐Trp‐Gly‐OH) reasonably reproduced a native‐like β‐hairpin structure in water although the C‐terminal and side‐chain conformations were different from the native ones. It was suggested that the SAAP force field is a useful tool for analyzing conformations of polypeptides in terms of intrinsic conformational propensities of the single amino acid units. © 2009 Wiley Periodicals, Inc. J Comput Chem, 2009 相似文献
499.
Hydrogenated amorphous Si (a-Si:H) has been applied to crystalline germanium (c-Ge) heterojunction solar cells and the influence of the surface treatments applied before a-Si:H deposition process has been studied. We found that PH3 exposure treatment after surface oxide removal by annealing is effective to improve c-Ge heterojunction solar cell performance. The conversion efficiency of the c-Ge heterojunction solar cell applied PH3 exposure treatment was up to 5.29% and the solar cell had better temperature coefficient than the c-Ge homojunction solar cell. These results suggest that the c-Ge substrate surface after oxide removal by annealing is covered with negatively charged dangling bonds, and the phosphorus adsorbed onto the c-Ge surface provides electron as a donor and corrects the band bending induced by negatively charged dangling bonds. 相似文献
500.
Oxovanadium complex bearing 3-hydroxypicolinic acid (H2hpic), that is, VO(Hhpic)2, successfully catalyzes a highly selective oxidation of benzylamines to the corresponding N-(benzylidene)benzylamines under atmospheric molecular oxygen. In addition, the use of imidazolium-type ionic liquids as solvent makes it possible to attain recycling of the catalyst. 相似文献