全文获取类型
收费全文 | 1751篇 |
免费 | 41篇 |
国内免费 | 3篇 |
专业分类
化学 | 1417篇 |
晶体学 | 16篇 |
力学 | 10篇 |
数学 | 26篇 |
物理学 | 326篇 |
出版年
2022年 | 11篇 |
2021年 | 7篇 |
2020年 | 7篇 |
2019年 | 26篇 |
2018年 | 12篇 |
2017年 | 12篇 |
2016年 | 24篇 |
2015年 | 20篇 |
2014年 | 41篇 |
2013年 | 94篇 |
2012年 | 84篇 |
2011年 | 95篇 |
2010年 | 54篇 |
2009年 | 45篇 |
2008年 | 87篇 |
2007年 | 79篇 |
2006年 | 76篇 |
2005年 | 94篇 |
2004年 | 76篇 |
2003年 | 62篇 |
2002年 | 59篇 |
2001年 | 62篇 |
2000年 | 64篇 |
1999年 | 35篇 |
1998年 | 29篇 |
1997年 | 32篇 |
1996年 | 29篇 |
1995年 | 21篇 |
1994年 | 34篇 |
1993年 | 36篇 |
1992年 | 42篇 |
1991年 | 29篇 |
1990年 | 20篇 |
1989年 | 27篇 |
1988年 | 11篇 |
1987年 | 8篇 |
1986年 | 11篇 |
1985年 | 29篇 |
1984年 | 28篇 |
1983年 | 28篇 |
1982年 | 15篇 |
1981年 | 17篇 |
1980年 | 17篇 |
1979年 | 24篇 |
1978年 | 19篇 |
1977年 | 11篇 |
1976年 | 15篇 |
1975年 | 9篇 |
1974年 | 9篇 |
1973年 | 4篇 |
排序方式: 共有1795条查询结果,搜索用时 125 毫秒
991.
Lithuanian Mathematical Journal - In this paper, we prove the universality theorem for the iterated integrals of the logarithm of the Riemann zeta-function on a line parallel to the real axis. 相似文献
992.
Endo M. Okazaki S. Matsunaga H. Moriyama S. Munaoka K. Yanase K. 《Experimental Techniques》2016,40(3):1065-1073
Experimental Techniques - The investigation of the behavior of small shear-mode fatigue cracks in the high-cycle fatigue regime is essential to understand the mechanism of rolling-contact fatigue... 相似文献
993.
We give a uniform and elementary treatment of many classical and new triply periodic minimal surfaces in Euclidean space,
based on a Schwarz–Christoffel formula for periodic polygons in the plane. Our surfaces share the property that vertical symmetry
planes cut them into simply connected pieces.
S. Fujimori was partially supported by JSPS Grant-in-Aid for Young Scientists (Start-up) 19840035. M. Weber’s material is
based upon work for the NSF under Award No. DMS-0139476. 相似文献
994.
Yusuke Sakai Yousuke Itoh Piljong Jung Keiko Kokeyama Chihiro Kozakai Katsuko T. Nakahira Shoichi Oshino Yutaka Shikano Hirotaka Takahashi Takashi Uchiyama Gen Ueshima Tatsuki Washimi Takahiro Yamamoto Takaaki Yokozawa 《Annalen der Physik》2024,536(2):2200140
Transient noise appearing in the data from gravitational-wave detectors frequently causes problems, such as instability of the detectors and overlapping or mimicking gravitational-wave signals. Because transient noise is considered to be associated with the environment and instrument, its classification would help to understand its origin and improve the detector's performance. In a previous study, an architecture for classifying transient noise using a time–frequency 2D image (spectrogram) is proposed, which uses unsupervised deep learning combined with variational autoencoder and invariant information clustering. The proposed unsupervised-learning architecture is applied to the Gravity Spy dataset, which consists of Advanced Laser Interferometer Gravitational-Wave Observatory (Advanced LIGO) transient noises with their associated metadata to discuss the potential for online or offline data analysis. In this study, focused on the Gravity Spy dataset, the training process of unsupervised-learning architecture of the previous study is examined and reported. 相似文献
995.
S. Lakshmi Reddy K. Sesha Maheswaramma G. Siva Reddy B. J. Reddy Tamio Endo Ray L. Frost 《Transition Metal Chemistry》2010,35(3):331-336
Natural iowaite, magnesium–ferric oxychloride mineral having light green color originating from Australia has been characterized
by EPR, optical, IR, and Raman spectroscopy. The optical spectrum exhibits a number of electronic bands due to both Fe(III)
and Mn(II) ions in iowaite. From EPR studies, the g values are calculated for Fe(III) and g and A values for Mn(II). EPR and optical absorption studies confirm that Fe(III) and Mn(II) are in distorted octahedral geometry.
The bands that appear both in NIR and Raman spectra are due to the overtones and combinations of water and carbonate molecules.
Thus EPR, optical, and Raman spectroscopy have proven most useful for the study of the chemistry of natural iowaite and chemical
changes in the mineral. 相似文献
996.
Partitioning coefficients into differing acyclic aliphatic alcohols can be described by the linear solvation energy relationship (LSER) equations with 6 fitting parameters to the accuracy of 0.19–0.20 log units. If 6 more fitting parameters are added to account for the slight dependency of the partitioning coefficients on the number of carbon atoms of alcohols, the accuracy improves to 0.15–0.16, comparable to the performance by the 30-parameter model proposed by Sprunger et al. [1]. 相似文献
997.
The compressibility of the bound rubber around the silica particle was evaluated by an acoustic technique. The density and the longitudinal wave velocity of a silica/SBR compound were measured as a function of the silica content. The density increased linearly with the filler content. The longitudinal wave velocity was almost constant within the experimental error. The mass ratio of the bound rubber to the silica in the silica/SBR compounds was 1.08+/-0.03 kg kg(-1) which was measured by a thermal gravimetric analysis (TGA). The partial specific adiabatic compressibility of the silica was estimated as (0.1+/-0.5) x 10(-10) Pa(-1) on the basis of a three states model. The adiabatic compressibility of the bound rubbers in the silica/SBR compounds was (4.6+/-0.5) x 10(-10) Pa(-1). The compressibility was almost the same as that of the SBR, and the value was twice larger than the compressibility of the bound rubber formed in a CB/SBR composite. 相似文献
998.
Hiroaki Iwamoto Kohei Endo Yu Ozawa Yuta Watanabe Koji Kubota Tsuneo Imamoto Hajime Ito 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(32):11229-11234
The first copper(I)‐catalyzed enantioselective borylation of racemic benzyl chlorides has been realized by a quadrant‐by‐quadrant structure modulation of QuinoxP*‐type bisphosphine ligands. This reaction converts racemic mixtures of secondary benzyl chlorides into the corresponding chiral benzylboronates with high enantioselectivity (up to 92 % ee). The results of mechanistic studies suggest the formation of a benzylic radical intermediate. The results of DFT calculations indicate that the optimal bisphosphine‐copper(I) catalyst engages in noncovalent interactions that efficiently recognize the radical intermediate, and leads to high levels of enantioselectivity. 相似文献
999.
The catalytic enantioselective difluoromethylation of arylidene Meldrum's acids with (difluoromethyl)zinc reagent, easily prepared through zinc/iodide exchange reaction of difluoroiodomethane and diethylzinc with co-solvent such as pyridines, by a chiral phosphoramidite-Cu catalyst is shown to provide highly enantioselective sp [3]-difluoromethyl Michael addition product in good yields and high levels of enantioselectivity. 相似文献
1000.
J. Sato M. Kikukawa S. Yamaguchi M. Endo K. Tei K. Nanri T. Fujioka 《Applied physics. B, Lasers and optics》2009,96(4):741-744
A flexible and portable trace nitrogen dioxide sensor based on cavity ringdown spectroscopy using an optical fiber-coupled
high-finesse cavity was successfully demonstrated. Tailoring the spatial mode matching condition of the core of an optical
fiber and high-finesse external cavity allows for effective optical feedback into an antireflection-coated laser diode for
stable resonant enhancement of the external cavity. The external cavity, which works as a ringdown cavity, could be remotely
located from the light source and receiver section by only a single mode optical fiber. The sensitivity was found to be 1.0×10−7 cm−1 in a compact 1-cm3 ringdown cavity volume. 相似文献