全文获取类型
收费全文 | 176812篇 |
免费 | 2823篇 |
国内免费 | 676篇 |
专业分类
化学 | 96434篇 |
晶体学 | 1991篇 |
力学 | 7682篇 |
综合类 | 5篇 |
数学 | 18996篇 |
物理学 | 55203篇 |
出版年
2021年 | 941篇 |
2020年 | 1284篇 |
2019年 | 1307篇 |
2018年 | 1263篇 |
2017年 | 1273篇 |
2016年 | 2704篇 |
2015年 | 2272篇 |
2014年 | 2892篇 |
2013年 | 8468篇 |
2012年 | 7105篇 |
2011年 | 8663篇 |
2010年 | 5333篇 |
2009年 | 5267篇 |
2008年 | 7883篇 |
2007年 | 7790篇 |
2006年 | 7595篇 |
2005年 | 7060篇 |
2004年 | 6270篇 |
2003年 | 5373篇 |
2002年 | 4877篇 |
2001年 | 5924篇 |
2000年 | 4354篇 |
1999年 | 3221篇 |
1998年 | 2374篇 |
1997年 | 2428篇 |
1996年 | 2386篇 |
1995年 | 2261篇 |
1994年 | 2159篇 |
1993年 | 2032篇 |
1992年 | 2339篇 |
1991年 | 2296篇 |
1990年 | 2009篇 |
1989年 | 1978篇 |
1988年 | 2022篇 |
1987年 | 1950篇 |
1986年 | 1882篇 |
1985年 | 2828篇 |
1984年 | 2786篇 |
1983年 | 2207篇 |
1982年 | 2410篇 |
1981年 | 2299篇 |
1980年 | 2258篇 |
1979年 | 2199篇 |
1978年 | 2277篇 |
1977年 | 2224篇 |
1976年 | 2165篇 |
1975年 | 2132篇 |
1974年 | 2043篇 |
1973年 | 2119篇 |
1972年 | 1197篇 |
排序方式: 共有10000条查询结果,搜索用时 228 毫秒
1.
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
2.
Journal of Analytical Chemistry - The review considers the historical aspects of the formation and development of bioelectrochemistry and some issues of the analytical application of... 相似文献
3.
4.
A model with 16 moments is here presented in the framework of RET of polyatomic gases. It furnishes as principal subsystem the relativistic counterpart of a work by Arima T., Ruggeri T., Sugiyama M.; this is present in literature and treats the non relativistic case which incorporates relaxation processes of molecular rotation and vibration. Another principal subsystem is the natural extension of the 14 moments model by Pennisi S. and Ruggeri T.; this is also present in literature in the relativistic framework but where the trace of the third balance equation is neglected. Its extension is found here for the case when this trace isn’t neglected.
相似文献5.
6.
7.
Gómez M. J. Marklund P. Strombergsson D. Castejón C. García-Prada J. C. 《Experimental Techniques》2021,45(1):1-12
Experimental Techniques - In the last years, the wind industry has increased in a large scale. A wind turbine out of service leeds to high costs due to both maintenance and repair costs and the... 相似文献
8.
Lera Israel Leka Khasnabis Sutripto Wangatia Lodrick Makokha Femi Olu Emmanuel Ramamurthy Praveen C 《Journal of Solid State Electrochemistry》2022,26(1):195-209
Journal of Solid State Electrochemistry - Highly efficient, abundant, and low-cost materials are highly demanded for energy conversion applications to address the rising consumption of energy. In... 相似文献
9.
We consider kinetic models for a multi component gas mixture without chemical reactions. In the literature, one can find two types of BGK models in order to describe gas mixtures. One type has a sum of BGK type interaction terms in the relaxation operator, for example the model described by Klingenberg, Pirner and Puppo [20] which contains well-known models of physicists and engineers for example Hamel [16] and Gross and Krook [15] as special cases. The other type contains only one collision term on the right-hand side, for example the well-known model of Andries, Aoki and Perthame [1]. For each of these two models [20] and [1], we prove existence, uniqueness and positivity of solutions in the first part of the paper. In the second part, we use the first model [20] in order to determine an unknown function in the energy exchange of the macroscopic equations for gas mixtures described by Dellacherie [11]. 相似文献
10.
A CE instrument that can be assembled from commercially available components with minimal construction effort is described. Except for the electronic control circuitry no specially made parts are required. It is based on a flexible design of microfluidic, electropneumatic, and electronic sections and different configurations can easily be implemented. Automated injection into the capillary is performed hydrodynamically by the application of a pressure for a controlled length of time. The performance of the device was tested with a contactless conductivity detector by separating different metal ions. In addition, nine metal cations related to the quality of honey were separated in 2.3 min and four honey samples were analysed quantitatively to demonstrate the applicability of the method. 相似文献