全文获取类型
收费全文 | 6456篇 |
免费 | 161篇 |
国内免费 | 25篇 |
专业分类
化学 | 4564篇 |
晶体学 | 79篇 |
力学 | 79篇 |
数学 | 293篇 |
物理学 | 1627篇 |
出版年
2022年 | 39篇 |
2021年 | 44篇 |
2020年 | 67篇 |
2019年 | 82篇 |
2018年 | 64篇 |
2017年 | 53篇 |
2016年 | 107篇 |
2015年 | 109篇 |
2014年 | 146篇 |
2013年 | 321篇 |
2012年 | 300篇 |
2011年 | 355篇 |
2010年 | 190篇 |
2009年 | 189篇 |
2008年 | 364篇 |
2007年 | 303篇 |
2006年 | 326篇 |
2005年 | 313篇 |
2004年 | 306篇 |
2003年 | 244篇 |
2002年 | 267篇 |
2001年 | 160篇 |
2000年 | 174篇 |
1999年 | 97篇 |
1998年 | 72篇 |
1997年 | 73篇 |
1996年 | 77篇 |
1995年 | 48篇 |
1994年 | 69篇 |
1993年 | 93篇 |
1992年 | 95篇 |
1991年 | 81篇 |
1990年 | 69篇 |
1989年 | 58篇 |
1988年 | 78篇 |
1987年 | 75篇 |
1986年 | 76篇 |
1985年 | 114篇 |
1984年 | 106篇 |
1983年 | 41篇 |
1982年 | 75篇 |
1981年 | 87篇 |
1980年 | 77篇 |
1979年 | 67篇 |
1978年 | 56篇 |
1977年 | 72篇 |
1976年 | 56篇 |
1975年 | 42篇 |
1974年 | 51篇 |
1973年 | 32篇 |
排序方式: 共有6642条查询结果,搜索用时 0 毫秒
61.
Naganawa H Suzuki H Noro J Kimura T 《Chemical communications (Cambridge, England)》2005,(23):2963-2965
The weakly coordinating hydrophobic anion TFPB-, whose surface is covered with a hydrophobic field, gives rise to a selective separation of Am(III) from lanthanides(III) in their solvent extraction even with a hard-donor extractant that shows no selectivity for Am(III) in traditional solvent extraction. 相似文献
62.
To examine the antithrombogenicity of cultured endothelial cell-detached surface, a simple hybrid vascular model tube consisting of a glass tube and endothelial cells was constructed. To detach the endothelial cells from the inner surface of the model tube, a steady shear stress of 2 or 8 N m(-2) was imposed onto the surface of endothelial cell monolayer by means of a coaxial double cylinder rotational-type apparatus. Coagulation of blood in contact with the endothelial cell-detached surface was examined using a damped oscillation rheometer. Coagulation of whole blood in the cell-detached tube occurred at about 40 min, which was almost the same as that in the endothelial cell-coated tube. A few platelets without shape change adhered to the endothelial cell-detached surface. These data suggest that the endothelial cell-detached surface may exhibit antithrombogenic and anticoagulant surfaces. Biochemical analyses showed that the glass surface, where endothelial cell was detached, was covered with components such as collagen type IV that is considered to be produced from the endothelial cells on the glass surface. 相似文献
63.
Peptide-mediated protein delivery into living cells has been attracting our attention. Among the peptides that have been reported to have carrier activity, the one from the human immunodeficient virus (HIV)-1 Tat has been most often used for the introduction of exogenous macromolecules into cells. We have shown that not only the Tat peptide, but also various arginine-rich peptides showed very similar characteristics in translocation, and the possible presence of ubiquitous internalization mechanisms among the arginine-rich peptides has also been suggested. These arginine-rich peptides includes ones derived from HIV-1 Rev and flock house virus coat proteins. The linear- and branched-chain peptides containing approximately 8 residues of arginine also show a similar ability. In this review, we present the structural variety of membrane permeable peptides and provide a survey of the findings on the translocation of these peptides through the cell membranes. 相似文献
64.
A nondestructive photon activation procedure with 30 MeV bremsstrahlung followed by high-resolution gamma-spectrometry has
been applied to the multielement determination in tobacco leaves and commercial cigarettes. The elements determined by this
method included essential minor elements such as Ca, Cl, K and Mg, essential trace elements such as Fe, Mn and Zn, and possibly
toxic elements such As and Sb. The NBS Orchard Leaves could successfully be used as a comparative standard. The method is
quite simple and gives good reproducible results for at least 12 elements. 相似文献
65.
Komatsu H Iwasawa N Citterio D Suzuki Y Kubota T Tokuno K Kitamura Y Oka K Suzuki K 《Journal of the American Chemical Society》2004,126(50):16353-16360
The role of intracellular magnesium ions is of high interest in the fields of pharmacology and cellular biology. To accomplish the dynamic and three-dimensional imaging of intracellular Mg2+, there is a strong desire for the development of optimized Mg2+ fluorescent probes. In this paper we describe the design, synthesis, and cellular application of the three novel Mg2+ fluorescent probes KMG-101, -103, and -104. The compounds of this series feature a charged beta-diketone as a binding site specific for Mg2+ and a fluorescein residue as the fluorophore that can be excited with an Ar+ laser such as is widely used in confocal scanning microscopy. This molecular design leads to an intensive off-on-type fluorescent response toward Mg2+ ions. The two fluorescent probes KMG-103 and -104 showed suitable dissociation constants (Kd,Mg2+ = 2 mM) and nearly a 10-fold fluorescence enhancement over the intracellular magnesium ion concentration range (0.1-6 mM), allowing high-contrast, sensitive, and selective Mg2+ measurements. For intracellular applications, the membrane-permeable probe KMG-104AM was synthesized and successfully incorporated into PC12 cells. Upon application of the mitochondria uncoupler FCCP to the probe-incorporated cells, the resulting increase in the free magnesium ion concentration could be followed over time. By using a confocal microscope, the intracellular 3D magnesium ion concentration distributions were satisfactorily observed. 相似文献
66.
67.
68.
Antitumor and immunomodulating activities of a beta-glucan obtained from liquid-cultured Grifola frondosa 总被引:5,自引:0,他引:5
I Suzuki K Hashimoto S Oikawa K Sato M Osawa T Yadomae 《Chemical & pharmaceutical bulletin》1989,37(2):410-413
The effects of the beta-1,3-glucan, LELFD, obtained from liquid-cultured mycelium of Grifola frondosa, on the growth of syngeneic tumors and immune responses in mice were examined. In Meth A or IMC solid tumor systems, LELFD administered intraperitoneally (i.p.) or intralesionally (i.l.) exhibited significant antitumor effects. However, the growth of L1210 and P388 leukemias was unaffected by the injection of LELFD. The injection of LELFD i.p. enhanced the activities of natural killer cells and macrophages in mice. LELFD also enhanced the antibody response when it was injected i.p. with sheep red blood cells into mice. Furthermore, it was found that LELFD could activate the alternative complement pathway. 相似文献
69.
[reaction: see text] Base-promoted cyclocondensation of C-chloro oximes with cyclic 1,3-diketones affords functionalized isoxazoles in good yield and under convenient reaction conditions. This process enables the synthesis of highly substituted products with notable functional group tolerance. The products obtained are directly converted to a variety of polyketide-derived polycyclic structures including xanthenes, anthracenes, and benzophenones. 相似文献
70.
Masaaki Tomura Md. Akhtaruzzaman Kazuharu Suzuki Yoshiro Yamashita 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(7):o373-o375
In the crystal structures of the title compounds, C6H2I2N2S, (I), and C12H4I2N4S2, (II), respectively, a large number of short inter‐heteroatom contacts, such as S?N, I?I and N?I, are observed. In (II), which is non‐centrosymmetric, two halves of the molecule are related by a crystallographic twofold axis. 相似文献