全文获取类型
收费全文 | 354454篇 |
免费 | 2229篇 |
国内免费 | 994篇 |
专业分类
化学 | 159046篇 |
晶体学 | 5235篇 |
力学 | 19591篇 |
综合类 | 4篇 |
数学 | 68856篇 |
物理学 | 104945篇 |
出版年
2018年 | 18363篇 |
2017年 | 19001篇 |
2016年 | 11030篇 |
2015年 | 3261篇 |
2014年 | 2789篇 |
2013年 | 8279篇 |
2012年 | 12281篇 |
2011年 | 26827篇 |
2010年 | 15972篇 |
2009年 | 16335篇 |
2008年 | 21612篇 |
2007年 | 26771篇 |
2006年 | 6323篇 |
2005年 | 13660篇 |
2004年 | 9807篇 |
2003年 | 9450篇 |
2002年 | 6548篇 |
2001年 | 6159篇 |
2000年 | 4950篇 |
1999年 | 3698篇 |
1998年 | 2972篇 |
1997年 | 2927篇 |
1996年 | 3042篇 |
1995年 | 2716篇 |
1994年 | 2553篇 |
1993年 | 2461篇 |
1992年 | 2906篇 |
1991年 | 2793篇 |
1990年 | 2742篇 |
1989年 | 2778篇 |
1988年 | 2727篇 |
1987年 | 2731篇 |
1986年 | 2539篇 |
1985年 | 3403篇 |
1984年 | 3420篇 |
1983年 | 2853篇 |
1982年 | 3046篇 |
1981年 | 2974篇 |
1980年 | 2884篇 |
1979年 | 3040篇 |
1978年 | 3287篇 |
1977年 | 3021篇 |
1976年 | 2971篇 |
1975年 | 2818篇 |
1974年 | 2766篇 |
1973年 | 2818篇 |
1972年 | 1814篇 |
1968年 | 2039篇 |
1967年 | 2185篇 |
1966年 | 1983篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
S. V. Panin I. V. Vlasov V. P. Sergeev B. B. Ovechkin P. O. Marushchak Sunder Ramasubbu P. S. Lyubutin V. V. Titkov 《Physical Mesomechanics》2015,18(3):261-272
The structure and properties of 12Cr1MoV steel irradiated with a zirconium ion beam were studied by optical microscopy, scanning electron microscopy, and micro- and nanoindentation. It is shown that the modification covers the entire cross-section of the irradiated specimens to a depth of 1 mm. The data on irradiation-induced structural changes are used to interpret the changes in mechanical properties of the irradiated specimens under static and cyclic loading. Particular attention is given to analysis of strain estimation by the digital image correlation method. 相似文献
32.
He Haidong Yang Haifeng Zhou Longpeng Chen Tianchi 《Journal of Russian Laser Research》2015,36(3):292-299
Ni–Co alloys have a wide range of applications in various fields owning to their excellent physical, chemical, and mechanical properties. In this paper, we prepare Ni–Co alloy coatings on 316L stain steel surfaces by electroplating. We present a novel approach utilizing a nanosecond laser to induce microtextures on Ni–Co alloy coatings. We study experimentally the effects of laser power and scanning rate on the surface morphologies of Ni–Co alloy coatings. The results indicate that the shape and size of induced microtextures can be controlled by the laser power and scanning rate. The size of grains increases with increase in the work current of the laser (WCL) at a certain scanning rate. With the WCL constant, the size of grains decreases with increase in scanning rate while their average height increases. It is a simple and easily-controlled method for the fabrication of microstructures on Ni–Co alloy coatings, which has promising applications in investigations of the properties of microtextured surfaces, such as friction, adhesion, and wetting. 相似文献
33.
34.
Kinetics and Catalysis - Boron and barium were employed as dopants for the VMgO system. The catalysts were characterized by ICP-OES, BET, IR, powder XRD, EDX, TPR-H2, TPD-NH3, XPS, and 51V MAS NMR.... 相似文献
35.
Chris H. Hill Agnete H. Viuff Samantha J. Spratley Stéphane Salamone Stig H. Christensen Randy J. Read Nigel W. Moriarty Henrik H. Jensen Janet E. Deane 《Chemical science》2015,6(5):3075-3086
Krabbe disease is a devastating neurodegenerative disorder characterized by rapid demyelination of nerve fibers. This disease is caused by defects in the lysosomal enzyme β-galactocerebrosidase (GALC), which hydrolyzes the terminal galactose from glycosphingolipids. These lipids are essential components of eukaryotic cell membranes: substrates of GALC include galactocerebroside, the primary lipid component of myelin, and psychosine, a cytotoxic metabolite. Mutations of GALC that cause misfolding of the protein may be responsive to pharmacological chaperone therapy (PCT), whereby small molecules are used to stabilize these mutant proteins, thus correcting trafficking defects and increasing residual catabolic activity in cells. Here we describe a new approach for the synthesis of galacto-configured azasugars and the characterization of their interaction with GALC using biophysical, biochemical and crystallographic methods. We identify that the global stabilization of GALC conferred by azasugar derivatives, measured by fluorescence-based thermal shift assays, is directly related to their binding affinity, measured by enzyme inhibition. X-ray crystal structures of these molecules bound in the GALC active site reveal which residues participate in stabilizing interactions, show how potency is achieved and illustrate the penalties of aza/iminosugar ring distortion. The structure–activity relationships described here identify the key physical properties required of pharmacological chaperones for Krabbe disease and highlight the potential of azasugars as stabilizing agents for future enzyme replacement therapies. This work lays the foundation for new drug-based treatments of Krabbe disease. 相似文献
36.
37.
38.
39.
40.