全文获取类型
收费全文 | 384343篇 |
免费 | 2680篇 |
国内免费 | 932篇 |
专业分类
化学 | 171062篇 |
晶体学 | 5077篇 |
力学 | 21745篇 |
综合类 | 18篇 |
数学 | 74396篇 |
物理学 | 115657篇 |
出版年
2021年 | 2156篇 |
2020年 | 2327篇 |
2019年 | 2728篇 |
2018年 | 19109篇 |
2017年 | 19559篇 |
2016年 | 13593篇 |
2015年 | 4346篇 |
2014年 | 5271篇 |
2013年 | 11116篇 |
2012年 | 15259篇 |
2011年 | 28627篇 |
2010年 | 18118篇 |
2009年 | 18547篇 |
2008年 | 23618篇 |
2007年 | 28053篇 |
2006年 | 9539篇 |
2005年 | 14666篇 |
2004年 | 11076篇 |
2003年 | 10728篇 |
2002年 | 8284篇 |
2001年 | 6905篇 |
2000年 | 5805篇 |
1999年 | 4126篇 |
1998年 | 3813篇 |
1997年 | 3631篇 |
1996年 | 3235篇 |
1995年 | 2885篇 |
1994年 | 2803篇 |
1993年 | 2637篇 |
1992年 | 2908篇 |
1991年 | 3097篇 |
1990年 | 2857篇 |
1989年 | 2889篇 |
1988年 | 2747篇 |
1987年 | 2595篇 |
1986年 | 2486篇 |
1985年 | 3131篇 |
1984年 | 3337篇 |
1983年 | 2818篇 |
1982年 | 2992篇 |
1981年 | 2768篇 |
1980年 | 2690篇 |
1979年 | 2861篇 |
1978年 | 3161篇 |
1977年 | 2959篇 |
1976年 | 2937篇 |
1975年 | 2801篇 |
1974年 | 2844篇 |
1973年 | 2860篇 |
1972年 | 1925篇 |
排序方式: 共有10000条查询结果,搜索用时 234 毫秒
91.
S. Q. Hou W. Wang Z. Y. Wang Z. W. Hu K. Liu 《Journal of Applied Mechanics and Technical Physics》2018,59(1):153-162
In order to investigate the characteristics of force chains in a granular flow system, a parallel plate shear cell is constructed to simulate the shear movement of an infinite parallel plate and observe variations in relevant parameters. The shear dilatancy process is divided into three stages, namely, plastic strain, macroscopic failure, and granular recombination. The stickslip phenomenon is highly connected with the evolution of force chains during the shear dilatancy process. The load–distribution rate curves and patterns of the force chains are utilized to describe the load-carrying behaviors and morphologic changes of force chains separately. Force chains, namely, “diagonal gridding,” “tadpole-shaped,” and “pinnate” are defined according to the form of the force chains in the corresponding three stages. 相似文献
92.
93.
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
94.
Rachida M’chaar Abdelaziz Sabbar Mouloud El Moudane Noureddine Ouerfelli 《哲学杂志》2020,100(11):1415-1438
ABSTRACT By applying the geometric models and the theoretical equation, the surface tension, the molar volume and the density were studied. The empirical calculations were carried out in temperature range 623?K?≤?T?≤?1123?K. Only few thermophysical properties were estimated for eight quinary alloys: Sn3.55Ag0.5Cu3Bi3Sb, Sn3.48Ag0.5Cu3Bi5Sb, Sn3.48 Ag0.5Cu5Bi3Sb, Sn3.40 Ag0.5Cu5Bi5Sb, Sn3.53Ag1Cu3Bi3Sb, Sn3.46Ag1Cu3Bi5Sb, Sn3.46Ag1Cu5Bi3Sb, Sn3.38Ag1Cu5Bi5Sb. The results show that surface tension and density have a linear appearance for all temperatures. We have also studied the influence of the composition and temperature in the studied alloys. The obtained theoretical results are compared with the experimental ones and with the conventional Pb–Sn welds. 相似文献
95.
96.
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
97.
Echabaane M. Hfaiedh S. Smiri B. Saidi F. Dridi C. 《Journal of Solid State Electrochemistry》2021,25(6):1797-1806
Journal of Solid State Electrochemistry - The fast and sensitive detection of copper ions would be essential for water monitoring. Herein, we report a novel development of an impedimetric sensor... 相似文献
98.
Journal of Thermal Analysis and Calorimetry - Novel porous carbon sheets were developed as green, renewable, cost-effective, and efficient flame retardant material for thermoplastic polymers.... 相似文献
99.
JETP Letters - One of the main features of the dusty plasma compared to the conventional plasma (without charged dust particles is anomalous dissipation that is caused by the charging of dust... 相似文献
100.
Valiullina Z. R. Ivanova N. A. Shitikova O. V. Miftakhov M. S. 《Russian Journal of Organic Chemistry》2019,55(8):1131-1135
Russian Journal of Organic Chemistry - Methyl (Z)-3-[(2R,3R,4S,5S)-5-(2-methoxy-2-oxoethyl)-3,4-(isopropylidenedioxy)tetrahydrofuran-2-yl]-prop-2-enoate was synthesized, and its intramolecular... 相似文献