全文获取类型
收费全文 | 149797篇 |
免费 | 1580篇 |
国内免费 | 378篇 |
专业分类
化学 | 79949篇 |
晶体学 | 1637篇 |
力学 | 6589篇 |
综合类 | 7篇 |
数学 | 15172篇 |
物理学 | 48401篇 |
出版年
2020年 | 1111篇 |
2019年 | 1169篇 |
2018年 | 1475篇 |
2017年 | 1451篇 |
2016年 | 2466篇 |
2015年 | 1545篇 |
2014年 | 2422篇 |
2013年 | 6313篇 |
2012年 | 4925篇 |
2011年 | 6256篇 |
2010年 | 4279篇 |
2009年 | 4290篇 |
2008年 | 5691篇 |
2007年 | 5766篇 |
2006年 | 5406篇 |
2005年 | 4993篇 |
2004年 | 4393篇 |
2003年 | 3767篇 |
2002年 | 3577篇 |
2001年 | 4162篇 |
2000年 | 3108篇 |
1999年 | 2345篇 |
1998年 | 2041篇 |
1997年 | 2032篇 |
1996年 | 1837篇 |
1995年 | 1845篇 |
1994年 | 1844篇 |
1993年 | 1674篇 |
1992年 | 1943篇 |
1991年 | 2076篇 |
1990年 | 1867篇 |
1989年 | 1875篇 |
1988年 | 1822篇 |
1987年 | 1718篇 |
1986年 | 1657篇 |
1985年 | 2157篇 |
1984年 | 2299篇 |
1983年 | 1866篇 |
1982年 | 2051篇 |
1981年 | 1937篇 |
1980年 | 1857篇 |
1979年 | 2009篇 |
1978年 | 2177篇 |
1977年 | 2050篇 |
1976年 | 2090篇 |
1975年 | 2004篇 |
1974年 | 2059篇 |
1973年 | 2044篇 |
1972年 | 1341篇 |
1971年 | 1197篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Ukrainian Mathematical Journal - We establish new criteria of compatibility for a linear system of equations (equivalent to the Kronecker–Capelli theorem) or inequalities (equivalent to the... 相似文献
2.
Numerical Algorithms - In this paper, the block generalized product-type bi-conjugate gradient (GPBi-CG) method for solving large, sparse nonsymmetric linear systems of equations with multiple... 相似文献
3.
Nonlinear Dynamics - We present an enhanced version of the parametric nonlinear reduced-order model for shape imperfections in structural dynamics we studied in a previous work. In this model, the... 相似文献
4.
Kopytov G. F. Malyshko V. V. Goryachko A. I. Sharafan M. V. Churkina A. V. Moiseev A. V. Shashkov D. I. Lyasota O. M. 《Russian Physics Journal》2021,64(2):255-260
Russian Physics Journal - The specific features of the sorption activity of silver nanoparticles (AgNPs) on biodegradable polymers of natural (collagen) and artificial (polyamide 6.6) origin have... 相似文献
5.
6.
Semigroup Forum - It is well known that the set of isomorphism classes of extensions of groups with abelian kernel is characterized by the second cohomology group. In this paper we generalise this... 相似文献
7.
Alawainati F. A. Manaa H. Henari F. Z. Biyiklioglu Z. Arslan T. Jaafar A. 《Journal of Applied Spectroscopy》2021,88(5):951-957
Journal of Applied Spectroscopy - Detailed measurements of nonlinear optical properties and optical limiting for four phthalocyanine (Pc) derivatives (PcCo, PcCu, PcMn, and PcSi) are reported. The... 相似文献
8.
Restricted testing conditions were considered recently. For the maximal operator, Hytönen, Li and Sawyer [8] first obtained parental testing condition. Later, they [9] showed that it suffices to restrict testing to doubling cubes. Chen and Lacey [3] gave a similar restricted testing condition. In our paper, we discuss a version of the latter in the multilinear setting.
相似文献9.
Atopic dermatitis is characterized by leukocyte migration into the skin dermis and typically driven by excessive chemokine production at the site of inflammation. Conventional topical formulations such as gels, creams, and ointments are insufficient for this treatment because of low penetration of drug molecules into the targeted skin tissues. Herein, using a simple, green, sustainable strategy, we have developed novel primary zein nanoparticles embedded in curcumin (Cur) and coated with silk sericin (ZHSCs) for the topical delivery of Cur to penetrate into the dermis and exercise anti-dermatitis effects on the lesion with minimal side-effects. Transdermal delivery experiments and porcine skin fluorescence imaging indicated that ZHSCs facilitate the penetration of Cur across the epidermis layer of skin to reach deep-seated sites. Notably, ZHSCs = 1:0.25 (zein-to-silk sericin mass ratios of 1:0.25) markedly elevated the skin permeability and cumulative turnover of Cur transferred, which were provided a greater than a 3.8-fold increase relative to free Cur. The special nanoparticles of ZHS = 1:0.25 possessed the deepest localization depth and experience a transition of the particle structure and core-shell separation after penetrating into the dermis of skin. In a cell model of dermatitis induced by tumor necrosis factor α/interferon γ co-stimulation, compared with free Cur, Cur-loaded ZHS nanoparticles down-regulated the generation of inflammatory cytokines and chemokines in keratinocytes through suppression of the nuclear translocation of NF-κBp65 and hence exerted an anti-dermatitis effect. This strategy may provide new avenues and direction for the demanding issues of valid topical delivery systems. 相似文献
10.
Russian Chemical Bulletin - New representatives of (O-Si)-chelate compounds, N-(fluorosilyl)methyl derivatives of N-methylacetamide, N-methylbenzamide, N-phenylacetamide, and N-phenylbenzamide,... 相似文献