全文获取类型
收费全文 | 3064篇 |
免费 | 118篇 |
国内免费 | 21篇 |
专业分类
化学 | 2470篇 |
晶体学 | 26篇 |
力学 | 19篇 |
数学 | 188篇 |
物理学 | 500篇 |
出版年
2023年 | 18篇 |
2022年 | 19篇 |
2021年 | 30篇 |
2020年 | 35篇 |
2019年 | 57篇 |
2018年 | 33篇 |
2017年 | 31篇 |
2016年 | 70篇 |
2015年 | 73篇 |
2014年 | 78篇 |
2013年 | 161篇 |
2012年 | 196篇 |
2011年 | 225篇 |
2010年 | 132篇 |
2009年 | 120篇 |
2008年 | 211篇 |
2007年 | 199篇 |
2006年 | 149篇 |
2005年 | 165篇 |
2004年 | 168篇 |
2003年 | 129篇 |
2002年 | 142篇 |
2001年 | 38篇 |
2000年 | 53篇 |
1999年 | 37篇 |
1998年 | 35篇 |
1997年 | 30篇 |
1996年 | 33篇 |
1995年 | 34篇 |
1994年 | 30篇 |
1993年 | 32篇 |
1992年 | 31篇 |
1991年 | 26篇 |
1990年 | 21篇 |
1989年 | 23篇 |
1988年 | 24篇 |
1987年 | 16篇 |
1986年 | 34篇 |
1985年 | 36篇 |
1984年 | 41篇 |
1983年 | 14篇 |
1982年 | 15篇 |
1981年 | 16篇 |
1980年 | 13篇 |
1979年 | 16篇 |
1978年 | 15篇 |
1977年 | 11篇 |
1975年 | 17篇 |
1974年 | 14篇 |
1973年 | 11篇 |
排序方式: 共有3203条查询结果,搜索用时 328 毫秒
171.
Tapping mode atomic force microscope has been applied to observe single-chain PMMAparticles which were stored for six months at room temperature after sprayed from verydilute solutions in good solvents, good/poor mixed solvents, and a theta solvent. Monodis-perse PMMA standards of molecular weights ranging from 7.90×10~4 to 1.3×10~6 wereused to investigate the effect of molecular weight oh the size of the single-chain PMMAparticles. These single-chain particles showed close to spherical shapes. The morphologyof single-chain PMMA particles of a given molecular weight was found to be identical inspite of different solvents used for solution spraying. Molecular weigh dependence of theparticle dimension was also found. The diameters of single-chain PMMA particles aftercorrection of tlp-geometry effect were compared to the values estimated from molecularweight and density. 相似文献
172.
Tatsuro Ouchi Hidetake Miyazaki Hidetoshi Arimura Fumitaka Tasaka Atsushi Hamada Yuichi Ohya 《Journal of polymer science. Part A, Polymer chemistry》2002,40(10):1426-1432
Amphiphilic AB‐type diblock copolymers composed of hydrophobic poly(L ‐lactide) (PLA) segments and hydrophilic poly(glycolic acid lysine) [poly(Glc‐Lys)] segments with amino side‐chain groups self‐associated to form PLA‐based polymeric micelles with amino surfaces in an aqueous solution. The average diameter of the loose core–shell polymeric micelles for poly(Glc‐Lys) [number‐average molecular weight (Mn) = 1240]‐b‐PLA (Mn = 7000) obtained by a dimethyl sulfoxide/water dialysis method was estimated to be about 50 nm in water by dynamic light scattering measurements. The size and shape of the obtained polymeric micelles were further observed with transmission electron microscopy and atomic force microscopy. To investigate the possibility of applying the obtained PLA‐based polymeric micelles as bioabsorbable vehicles for hydrophobic drugs, we tested the entrapment of drugs in poly(Glc‐Lys) (Mn = 1240)‐b‐PLA (Mn = 7000) micelles and their release with doxorubicin as a hydrophobic drug. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1426–1432, 2002 相似文献
173.
Proteome analysis of Oncorhynchus species during embryogenesis 总被引:3,自引:0,他引:3
Kanaya S Ujiie Y Hasegawa K Sato T Imada H Kinouchi M Kudo Y Ogata T Ohya H Kamada H Itamoto K Katsura K 《Electrophoresis》2000,21(9):1907-1913
To understand the molecular mechanisms underlying normal and abnormal development of two salmonids, masu salmon (Oncorhynchus masou) and rainbow trout (O. mykiss), we used two-dimensional (2-D) electrophoresis to construct a series of 2-D maps during the embryonic period. We identified all visible protein spots on the 2-D map by assigning numbers for masu salmon and rainbow trout, and we determined N-terminal sequences of proteins for one hundred of the spots, that appear at very high concentrations in the whole embryos of masu salmon and rainbow trout. We also characterized embryonic stages according to the periods of appearance of spots. Most of the N-terminal sequences were identical or at least highly similar to partial sequences reported for vitellogenin (Vtg) of O. mykiss. A potential proteolytic processing of Vtg for rainbow trout is discussed in relation to the time of appearance and relative position of Vtg fragments within the complete protein sequence. 相似文献
174.
175.
We study spectral distortions of diffuse ultra-high energy (UHE) neutrino flavour fluxes resulting due to physics beyond the Standard Model (SM). Even large spectral differences between flavours at the source are massaged into a common shape at earth by SM oscillations, thus, any significant observed spectral differences are an indicator of new physics present in the oscillation probability during propagation. Lorentz symmetry violation (LV) and neutrino decay are examples, and result in significant distortion of the fluxes and of the well-known bounds on them, which may allow UHE detectors to probe LV parameters, lifetimes and the mass hierarchy over a broad range. 相似文献
176.
Optical Review - A novel color removal method for digital color images is proposed. In this method, differences of colors in an input color image are reflected effectively, and the perceived... 相似文献
177.
Tsuyoshi Satoh Takayuki Kuramoto Shingo Ogata Hiroyuki Watanabe Takahito Saitou Makoto Tadokoro 《Tetrahedron: Asymmetry》2010,21(1):1-5
Treatment of enantiomerically pure 1-chlorovinyl p-tolyl sulfoxides, derived from cyclic ketones and (R)-chloromethyl p-tolyl sulfoxide, with the lithium enolate of tert-butyl carboxylates gave adducts in quantitative yields as single diastereomers. The adducts were treated with i-PrMgCl in toluene to afford optically active bicyclo[n.1.0]alkanes bearing a tert-butyl carboxylate moiety in up to 99% enantiomeric excess through the enantioselective 1,3-CH insertion reaction of the generated chiral magnesium carbenoids. This is the first example of the enantioselective 1,3-CH insertion reaction of magnesium carbenoid. 相似文献
178.
179.
180.
Atsushi Takamizawa Kayoko Mishina Kenzo Hiraoka 《Journal of mass spectrometry : JMS》2012,47(2):221-225
Covalent bonds are often created by a reaction between chemicals and protein before causing various adverse effects in a cell. Dimethylaminoethyl methacrylate (DMAEMA), which has moderate toxicity, causes skin inflammation and throat irritation. For this study, we investigated a reaction mechanism between myoglobin and (DMAEMA) using a new analytical tool developed at our laboratory: laser spray mass spectrometry technique. It was found that initially DMAEMA was added to the amino group of protein by the Michael addition mechanism; the added DMAEMA was hydrolyzed to methacrylic acid using an autocatalytic system. The results of this study indicate the feasibility of the laser spray technique in analyses of reaction dynamics. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献