全文获取类型
收费全文 | 658283篇 |
免费 | 31100篇 |
国内免费 | 18818篇 |
专业分类
化学 | 366996篇 |
晶体学 | 9498篇 |
力学 | 29682篇 |
综合类 | 48篇 |
数学 | 78954篇 |
物理学 | 223023篇 |
出版年
2020年 | 5448篇 |
2019年 | 6112篇 |
2018年 | 6791篇 |
2017年 | 7458篇 |
2016年 | 11523篇 |
2015年 | 8959篇 |
2014年 | 11869篇 |
2013年 | 31087篇 |
2012年 | 24116篇 |
2011年 | 30021篇 |
2010年 | 23929篇 |
2009年 | 23767篇 |
2008年 | 25658篇 |
2007年 | 25271篇 |
2006年 | 23975篇 |
2005年 | 22335篇 |
2004年 | 21149篇 |
2003年 | 18574篇 |
2002年 | 18038篇 |
2001年 | 19957篇 |
2000年 | 15316篇 |
1999年 | 12575篇 |
1998年 | 10454篇 |
1997年 | 10073篇 |
1996年 | 10303篇 |
1995年 | 9894篇 |
1994年 | 9686篇 |
1993年 | 9409篇 |
1992年 | 10094篇 |
1991年 | 9547篇 |
1990年 | 8940篇 |
1989年 | 8841篇 |
1988年 | 9033篇 |
1987年 | 8198篇 |
1986年 | 7890篇 |
1985年 | 10310篇 |
1984年 | 10512篇 |
1983年 | 8300篇 |
1982年 | 9111篇 |
1981年 | 8976篇 |
1980年 | 8596篇 |
1979年 | 8913篇 |
1978年 | 9084篇 |
1977年 | 9151篇 |
1976年 | 9126篇 |
1975年 | 8314篇 |
1974年 | 8216篇 |
1973年 | 8362篇 |
1972年 | 5432篇 |
1968年 | 4459篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
121.
Cover Picture: Coordination Chemistry of N‐Heterocyclic Nitrenium‐Based Ligands (Chem. Eur. J. 19/2015) 下载免费PDF全文
122.
Mariam Hakami Dr. Geetanjali Deokar Jasmin Smajic Dr. Nitin M. Batra Prof. Pedro M. F. J. Costa 《化学:亚洲杂志》2021,16(11):1466-1474
In the last decade, catalytic chemical vapor deposition (CVD) has been intensively explored for the growth of single-layer graphene (SLG). Despite the scattering of guidelines and procedures, variables such as the surface texture/chemistry of catalyst metal foils, carbon feedstock, and growth process parameters have been well-scrutinized. Still, questions remain on how best to standardize the growth procedure. The possible correlation of procedures between different CVD setups is an example. Here, two thermal CVD reactors were explored to grow graphene on Cu foil. The design of these setups was entirely distinct, one being a “showerhead” cold-wall type, whereas the other represented the popular “tubular” hot-wall type. Upon standardizing the Cu foil surface, it was possible to develop a procedure for cm2-scale SLG growth that differed only by the carrier gas flow rate used in the two reactors. 相似文献
123.
Ajeel Raheem K. Salim W. S.-I. W. 《Journal of Thermal Analysis and Calorimetry》2021,144(4):1161-1173
Journal of Thermal Analysis and Calorimetry - Over the last few decades, tremendous consideration is drawn towards corrugation surfaces because of their advantages over the improvement in thermal... 相似文献
124.
Herrasti P. Mazarío E. Recio Francisco J. 《Journal of Solid State Electrochemistry》2021,25(1):231-236
Journal of Solid State Electrochemistry - In this work, the use of neodymium electrodes as a basis for the immobilization of magnetite nanoparticles has been carried out. The sensitivity and... 相似文献
125.
Walter N. Harrington Christina M. Kackos Richard J. Webby 《Experimental & molecular medicine》2021,53(5):737
The influenza virus is a global threat to human health causing unpredictable yet recurring pandemics, the last four emerging over the course of a hundred years. As our knowledge of influenza virus evolution, distribution, and transmission has increased, paths to pandemic preparedness have become apparent. In the 1950s, the World Health Organization (WHO) established a global influenza surveillance network that is now composed of institutions in 122 member states. This and other surveillance networks monitor circulating influenza strains in humans and animal reservoirs and are primed to detect influenza strains with pandemic potential. Both the United States Centers for Disease Control and Prevention and the WHO have also developed pandemic risk assessment tools that evaluate specific aspects of emerging influenza strains to develop a systematic process of determining research and funding priorities according to the risk of emergence and potential impact. Here, we review the history of influenza pandemic preparedness and the current state of preparedness, and we propose additional measures for improvement. We also comment on the intersection between the influenza pandemic preparedness network and the current SARS-CoV-2 crisis. We must continually evaluate and revise our risk assessment and pandemic preparedness plans and incorporate new information gathered from research and global crises.Subject terms: Influenza virus, Infectious diseases 相似文献
126.
V. V. Sagaradze N. V. Kataeva V. A. Zavalishin K. A. Kozlov V. V. Makarov A. R. Kuznetsov 《哲学杂志》2020,100(14):1868-1879
ABSTRACT The authors present the results of an investigation in Fe–Ni-Cr austenitic alloys of the low-temperature deformation-induced segregations of nickel that form in the micro regions being (i) located close to grain- and subgrain boundaries and (ii) characteristic of the concentration and magnetic inhomogeneities indicated by the appearance of a dark diffraction contrast at the electron diffraction patterns taken from these regions typical (at the same time) of an enhanced value of Curie temperature. The observed effects were connected with the micro distortions caused by the local change of lattice parameter because of an increase in nickel concentration, as well as in the result of a magnetostriction dilatation. Using methods of the X-ray energy dispersive spectroscopy (XEDS) and atomic-probe body-section radiography (tomography – APT) has made it possible to determine the borders of those regions of austenite that were characteristic of an enhanced concentration of nickel in the fields of the localisation of a deformation-induced segregation of nickel in the vicinity of grain (subgrain) boundaries of austenitic alloys of the types Fe–13Cr–30Ni and Fe–37Ni–3Ti. 相似文献
127.
Thalia Tsiaka Panagiotis Zoumpoulakis Vassilia J. Sinanoglou Constantinos Makris Georgios A. Heropoulos Antony C. Calokerinos 《Analytica chimica acta》2015
High-energy assisted extraction techniques, like ultrasound assisted extraction (UAE) and microwave assisted extraction (MAE), are widely applied over the last years for the recovery of bioactive compounds such as carotenoids, antioxidants and phenols from foods, animals and herbal natural sources. Especially for the case of xanthophylls, the main carotenoid group of crustaceans, they can be extracted in a rapid and quantitative way with the use of UAE and MAE. 相似文献
128.
129.
I. F. Golovnev E. I. Golovneva L. A. Merzhievsky V. M. Fomin V. E. Panin 《Physical Mesomechanics》2015,18(3):179-186
Molecular dynamics simulation was performed to study the formation of cluster structure, interfaces, and surfaces with different curvature radii in a perfect nanocrystal passed through by a nonlinear wave. It is shown that this process is a type of nanostructure self-organization in response to an external energy flux with subsequent development of a strong rotational field. 相似文献
130.