全文获取类型
收费全文 | 843篇 |
免费 | 44篇 |
国内免费 | 1篇 |
专业分类
化学 | 692篇 |
晶体学 | 9篇 |
力学 | 14篇 |
数学 | 38篇 |
物理学 | 135篇 |
出版年
2022年 | 9篇 |
2021年 | 8篇 |
2020年 | 15篇 |
2019年 | 19篇 |
2018年 | 8篇 |
2017年 | 6篇 |
2016年 | 17篇 |
2015年 | 26篇 |
2014年 | 18篇 |
2013年 | 43篇 |
2012年 | 53篇 |
2011年 | 69篇 |
2010年 | 25篇 |
2009年 | 28篇 |
2008年 | 58篇 |
2007年 | 53篇 |
2006年 | 52篇 |
2005年 | 44篇 |
2004年 | 61篇 |
2003年 | 37篇 |
2002年 | 33篇 |
2001年 | 12篇 |
2000年 | 11篇 |
1999年 | 7篇 |
1998年 | 5篇 |
1997年 | 16篇 |
1996年 | 6篇 |
1995年 | 7篇 |
1994年 | 6篇 |
1993年 | 9篇 |
1992年 | 11篇 |
1991年 | 8篇 |
1990年 | 11篇 |
1989年 | 7篇 |
1988年 | 15篇 |
1987年 | 6篇 |
1986年 | 7篇 |
1985年 | 8篇 |
1984年 | 7篇 |
1982年 | 3篇 |
1981年 | 3篇 |
1980年 | 6篇 |
1979年 | 4篇 |
1977年 | 3篇 |
1975年 | 2篇 |
1974年 | 4篇 |
1973年 | 2篇 |
1972年 | 4篇 |
1969年 | 2篇 |
1967年 | 3篇 |
排序方式: 共有888条查询结果,搜索用时 31 毫秒
801.
Seiji Takechi Shin-ya Morinaga Atsuma Kurozumi Takashi Miyachi Masayuki Fujii Nobuyuki Hasebe Hiromi Shibata Takeshi Murakami Yukio Uchihori Nagaya Okada 《Radiation Physics and Chemistry》2010,79(5):603-605
The characteristics of radiation detector fabricated by stacking some piezoelectric lead zirconate titanate (PZT) elements were studied by irradiating it with a 400 MeV/n xenon (Xe) beam. Comparing between observed results from the detector and calculation results using Bethe–Bloch formula, it was found that the amplitude of the output voltage observed was dependent on the amount of ionization energy loss of Xe ion with PZT. 相似文献
802.
803.
A graph is said to be K1,n-free, if it contains no K1,n as an induced subgraph. We prove that for n ? 3 and r ? n ?1, if G is a K1,n-free graph with minimum degree at least (n2/4(n ?1))r + (3n ?6)/2 + (n ?1)/4r, then G has an r-factor (in the case where r is even, the condition r ? n ?1 can be dropped). 相似文献
804.
S. Shibata K. Takamiya Y. Ota N. Nogawa Y. Ito T. Shibata 《Journal of Radioanalytical and Nuclear Chemistry》2007,273(3):517-520
The 63Ni in copper samples exposed by the Hiroshima atomic bomb was clearly measured for the first time by liquid scientillation
method For the measurement, the chemical separation scheme previously developed was improved The obtained result was agreed
with that estimated by the new dosimetry system for atomic bomb survivor studies, DS02. 相似文献
805.
Plasmon mode imaging of single gold nanorods 总被引:5,自引:0,他引:5
We have investigated two-photon-induced photoluminescence images and spectra of single gold nanorods by using an apertured scanning near-field optical microscope. The observed PL spectrum of single gold nanorod can be explained by the radiative recombination of the electron-hole pair near the X and L symmetry points. PL images reveal characteristic features reflecting an eigenfunction of a specific plasmon mode as well as electric field distributions around the nanorod. 相似文献
806.
Y Mino H Usami N Ota Y Takeda T Ichihara T Fujita 《Chemical & pharmaceutical bulletin》1990,38(8):2204-2207
Inorganic constituents of the leaves of several kinds of plants growing on different soil types were investigated using energy-dispersive X-ray fluorescence spectrometry. The results can be summarized as follows: (1) Each plant exhibited a characteristic metals profile, even if they were grown on similar soil types. (2) As we would expect, the metals profile of the plant leaves depends on the inorganic constitution of the soil on which it is grown. However, the degree of the influence of the soil types on the metals profile of the plant differs according to the kind of inorganic element: Ca and Cu are almost independent of the soil types, but the Ti and Fe content is dependent upon the soil types. (3) Sr content of plant leaves is closely related to the ratio of Sr to Ca of the soil on which the plants are grown. (4) This information should be helpful in identifying the producing district or original plant of a crude drug by its metals profile. 相似文献
807.
Kenji Sasaki Yuichi Arimoto Hiromi Ohtomo Taiji Nakayama Takashi Hirota 《Journal of heterocyclic chemistry》1993,30(4):989-992
Synthesis of benzo[3,4]cyclohepta[1,2-e]pyrimido[1,2-c]pyrimidines, corresponding to the B,D-dihomo-11,13,15-triazasteroidal skeleton as a novel ring system is described. Their effects on reserpine-induced hypothermia in mice and inhibitory activity against collagen-induced platelet aggregation were also investigated. 相似文献
808.
K Tanizawa T Mano B Tonomura K Hiromi Y Kanaoka 《Chemical & pharmaceutical bulletin》1990,38(2):467-469
In the preceding paper, the preparation of fluorescent cross-linked subtilisin was described. In this paper we present the catalytic and binding properties of the modified enzyme. Kinetic analysis showed that the cross-linked dimeric subtilisin retained both catalytic activity and binding affinity toward synthetic substrates. These kinetic characteristics of the modified enzyme were nearly identical to those of the native enzyme. The modified enzyme also exhibited a specific interaction with Streptomyces subtilisin inhibitor (SSI) with 1 to 1 stoichiometry. The formation of a polymeric complex, which is the expected product with cross-linked subtilisin, was demonstrated. 相似文献
809.
Collision reactions between cyano radical (CN) and dimethylacetylene (C4H6) are thought to occur in the atmosphere of Saturn's moon Titan. However, it is difficult to reproduce reactions occurring in unique environments to study their dynamical processes. In this study, collision reactions between CN and C4H6 were investigated using ab initio molecular dynamics (AIMD) simulations. The simulation results were categorized into three kinds: nonreactive collision, incorporation, and substitution. Short-time Fourier transform analysis of velocity autocorrelation functions obtained by the AIMD simulations, which has been recently developed by our research group, was performed to examine the nonequilibrium condition of the vibrational states. Spectrograms, which correspond to the time evolution of power spectra, clarify the relationship between the three reaction channels and the dynamical changes of the vibrational states. 相似文献
810.
We recently proposed a new hydrogen-accepting parameter, S(HA), for monosubstituted (di)azines on the basis of the heat of formation calculated by the conductor-like screening model (COSMO) method. In this work, S(HA) values for monosubstituted thiophenes and furans were calculated and the results were applied to the analysis of relationships between log P (P: 1-octanol/water partition coefficient) and log k (k: retention factor obtained by reversed phase HPLC). The S(HA) parameter was found to work effectively as a hydrogen-bonding parameter in a range of heteroaromatic compounds. 相似文献