全文获取类型
收费全文 | 1277篇 |
免费 | 40篇 |
国内免费 | 2篇 |
专业分类
化学 | 985篇 |
晶体学 | 20篇 |
力学 | 10篇 |
数学 | 55篇 |
物理学 | 249篇 |
出版年
2023年 | 6篇 |
2022年 | 9篇 |
2021年 | 14篇 |
2020年 | 17篇 |
2019年 | 18篇 |
2018年 | 7篇 |
2017年 | 16篇 |
2016年 | 19篇 |
2015年 | 24篇 |
2014年 | 25篇 |
2013年 | 61篇 |
2012年 | 53篇 |
2011年 | 70篇 |
2010年 | 43篇 |
2009年 | 41篇 |
2008年 | 100篇 |
2007年 | 71篇 |
2006年 | 74篇 |
2005年 | 63篇 |
2004年 | 73篇 |
2003年 | 64篇 |
2002年 | 82篇 |
2001年 | 17篇 |
2000年 | 22篇 |
1999年 | 18篇 |
1998年 | 14篇 |
1997年 | 13篇 |
1996年 | 26篇 |
1995年 | 13篇 |
1994年 | 11篇 |
1993年 | 16篇 |
1992年 | 18篇 |
1991年 | 5篇 |
1990年 | 6篇 |
1989年 | 7篇 |
1988年 | 8篇 |
1987年 | 7篇 |
1986年 | 7篇 |
1985年 | 23篇 |
1984年 | 17篇 |
1983年 | 6篇 |
1982年 | 13篇 |
1981年 | 11篇 |
1980年 | 6篇 |
1979年 | 9篇 |
1978年 | 10篇 |
1977年 | 6篇 |
1976年 | 13篇 |
1973年 | 14篇 |
1968年 | 5篇 |
排序方式: 共有1319条查询结果,搜索用时 328 毫秒
161.
2-(2-Dithianyl)benzhydrols ( a-c) undergo facile cycloaddition reaction with maleic anhydride under thermal conditions to give 1-phenyl-naphthalenes ( a-c) in one step. The naphthalenes ( a-c) have been converted into the naphthalene lignan lactones, ( a-c) and ( a-c). 相似文献
162.
Annals of the Institute of Statistical Mathematics - In Part I the Khintchine’s uniqueness theorem for the class convergence of probability distributions is proved in a natural way by making... 相似文献
163.
Hiroshi Watanabe Takemoto Shin Hiromichi Matsuo Fumio Okuno Tsutomu Tsuji Midori Matsuoka Junichi Fukaura Hisashi Matsunaga 《Journal of voice》1994,8(4):340-346
The current study was carried out with particular emphasis on the association between phonetic function tests and alterations in the appearance of the hypopharyngeal and laryngeal mucosa, such as capillary dilatation, edema, and vocal fold injection after alcohol intake. The results demonstrated the occurrence of previously unrecognized pathophysiological changes associated with synchronous phonetic functions in the vocal pathway after alcohol intake. Serum ethanol and aldehyde concentration levels were evaluated hourly for 2.5 h after ingestion of alcohol. When an electronystagmogram showed the typical pattern of alcohol intake, the study was initiated. Occasionally, rhinography was performed on subjects complaining of a stuffy nose after alcohol intake. 相似文献
164.
Yuji Yaegashi Seiji Adachi Takahiro Wada Satoshi Takano H. Yamauchi 《Physica C: Superconductivity and its Applications》1992,190(4):433-436
Yb(Ba1−xSrx)2Cu4O8 (0.1x0.3) superconductors of the YBa2Cu4O8(“124”) structure were successfully synthesized using an O2-hot-isostaticc-pressing (HIP) technique. The samples were characterized with respect to the crystal structure and superconducting properties. The lattice parameters of the samples decreased as the substitution of Sr for Ba proceeded. The superconducting transition temperatures of all the Yb-“124” samples were more or less the same, being around 80 K. 相似文献
165.
In order to obtain clear scintigrams of small animals, some improvements were brought on a pinhole collimator. Then, using a human gamma camera with this collimator improved, bone scintigraphy was attempted in the rat mandible and maxilla, experimentally to examine the desirable conditions of scintigraphy. The most desirable bone scan images were obtained under the conditions that the pinhole was 1.5 mm in diameter, the distance between the collimator and the object was 0 cm, and the exposure was 400. 相似文献
166.
Homoorientaline 4 was oxidised with homogenised potato peelings along, followed by acetylation, to give 1-hydroxyhomoorientaline triacetate 9, the structure of which was determined by spectroscopic data and an alternative synthesis. 相似文献
167.
Seiji Takano 《Journal of multivariate analysis》1973,3(1):93-101
The problem of multivariate information analysis is considered. First, the interaction information in each dimension is defined analogously according to McGill [4] and then applied to Markov chains. The property of interaction information zero deeply relates to a certain class of weakly dependent random variables. For homogeneous, recurrent Markov chains with m states, m ≥ n ≥3, the zero criterion of n-dimensional interaction information is achieved only by (n ? 2)-dependent Markov chains, which are generated by some nilpotent matrices. Further for Gaussian Markov chains, it gives the decomposition rule of the variables into mutually correlated subchains. 相似文献
168.
169.
Liu SQ Kuroda-Sowa T Konaka H Suenaga Y Maekawa M Mizutani T Ning GL Munakata M 《Inorganic chemistry》2005,44(4):1031-1036
Three luminescent silver(I)-oligo(phenylenevinylene) complexes, [Ag2(bmsb)(ClO4)2] (1), [Ag2(bmsb)(H2O)4](BF4)2 (2), and [Ag2(bdb)(CF3SO3)2] (3) (bmsb = 1, 4-bis(methylstyryl)benzene, bdb = 4,4'-bis(2, 5-dimethylstryryl)biphenyl), have been synthesized and structurally characterized. Complexes 1 and 2 are 2D networks with unique metallocyclophane motifs. Complex 3 affords a 2D zigzag sheet, in which silver triflates form tubelike double chains and bdb molecules act as linkages. Complex 2 exhibits high electric conductivity because of columnar aromatic stackings formed through intra- and intermolecular pi-pi interactions. Complexes 1-3 in the solid state exhibit luminescence, of which excitation and emission maxima are shifted to longer wavelength as compared to those of the corresponding metal-free ligands. 相似文献
170.