全文获取类型
收费全文 | 316899篇 |
免费 | 2726篇 |
国内免费 | 1244篇 |
专业分类
化学 | 152782篇 |
晶体学 | 4393篇 |
力学 | 16380篇 |
综合类 | 2篇 |
数学 | 57919篇 |
物理学 | 89393篇 |
出版年
2020年 | 1764篇 |
2019年 | 2037篇 |
2018年 | 12533篇 |
2017年 | 12303篇 |
2016年 | 9694篇 |
2015年 | 3387篇 |
2014年 | 4149篇 |
2013年 | 11395篇 |
2012年 | 11630篇 |
2011年 | 19994篇 |
2010年 | 11920篇 |
2009年 | 12249篇 |
2008年 | 15253篇 |
2007年 | 17428篇 |
2006年 | 8542篇 |
2005年 | 9025篇 |
2004年 | 8409篇 |
2003年 | 8061篇 |
2002年 | 7078篇 |
2001年 | 7410篇 |
2000年 | 5601篇 |
1999年 | 4331篇 |
1998年 | 3699篇 |
1997年 | 3687篇 |
1996年 | 3469篇 |
1995年 | 3240篇 |
1994年 | 3016篇 |
1993年 | 3085篇 |
1992年 | 3344篇 |
1991年 | 3389篇 |
1990年 | 3190篇 |
1989年 | 3155篇 |
1988年 | 3217篇 |
1987年 | 3084篇 |
1986年 | 2980篇 |
1985年 | 4031篇 |
1984年 | 4184篇 |
1983年 | 3435篇 |
1982年 | 3789篇 |
1981年 | 3683篇 |
1980年 | 3562篇 |
1979年 | 3594篇 |
1978年 | 3810篇 |
1977年 | 3624篇 |
1976年 | 3829篇 |
1975年 | 3403篇 |
1974年 | 3527篇 |
1973年 | 3841篇 |
1972年 | 2344篇 |
1971年 | 1793篇 |
排序方式: 共有10000条查询结果,搜索用时 10 毫秒
81.
R. Wollny 《Fresenius' Journal of Analytical Chemistry》1885,24(1):47-56
Ohne Zusammenfassung 相似文献
82.
Salimgareeva V. N. Polevoi R. M. Kolesov S. V. Ostakhov S. S. Ponomareva V. A. Leplyanin G. V. 《Russian Journal of Applied Chemistry》2003,76(5):804-808
The luminescence and scintillation properties of poly(methyl methacrylate) containing 1,1,3-trimethyl-3-phenylindan were studied. 相似文献
83.
Landfill gas, cryotrapped on a loop fashioned from a length of a capillary gas chromatography (GC) column, was examined for volatile organometallic compounds (VOMCs) and for volatile organic compounds (VOCs) by using GC–mass spectrometry (MS). A large number of organic components were present and many were identified, but the only VOMCs present in high enough concentrations to be detected were trimethylstibine and tetramethyltin. The use of inductively coupled plasma (ICP)‐MS as an element‐specific detector allowed the identification of a number of other organometallic species in the landfill gas, including trimethylarsine and trimethylbismuth, and, for the first time, butyltrimethyltin and dibutyldimethyltin. The presence of molybdenum hexacarbonyl was confirmed. Gas from a large‐scale compost heap and from compost incubated in the laboratory contained iodomethane but no common VOMCs (GC–ICP‐MS). Only VOCs were present in forest air (GC–MS). Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
84.
A new parallel storm surge model, the Parallel Environmental Model (PEM), is developed and tested by comparisons with analytic solutions. The PEM is a 2‐D vertically averaged, wetting and drying numerical model and can be operated in explicit, semi‐implicit and fully implicit modes. In the implicit mode, the propagation, Coriolis and bottom friction terms can all be treated implicitly. The advection and diffusion terms are solved with a parallel Eulerian–Lagrangian scheme developed for this study. The model is developed specifically for use on parallel computer systems and will function accordingly in either explicit of implicit modes. Storm boundary conditions are based on a simple exponential decay of pressure from the centre of a storm. The simulated flooding caused by a major Category 5 hurricane making landfall in the Indian River Lagoon, Florida is then presented as an example application of the PEM. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
85.
86.
R.J Hand 《Journal of Non》2003,315(3):276-287
Glass may be strengthened by epoxy coatings although the strengthening mechanisms remain unclear. Possible strengthening mechanisms are reviewed and are used to analyse strength data for both a solvent based and a water based coating system. The coatings either fill (solvent based coatings), or partially fill (water based coatings) surface cracks and it is shown that closure stresses arising from the thermal expansion mismatch of the coating within these cracks can account for the observed degrees of strengthening. It is also demonstrated that other suggested mechanisms such as flaw healing cannot fully account for the observed degree of strengthening. 相似文献
87.
We prove new theorems on the justification of the averaging method for multifrequency oscillation systems with pulse influence at fixed times. 相似文献
88.
89.
We prove that the sufficient conditions for the asymptotic stability of impulsive systems obtained by Gurgula and Perestyuk are also necessary conditions. 相似文献
90.
Makarov V. L. Khlobystov V. V. Kashpur E. F. Mikhal'chuk B. R. 《Ukrainian Mathematical Journal》2003,55(6):942-955
We construct an integral Newton-type interpolation polynomial with a continual set of nodes. This interpolant is unique and preserves an operator polynomial of the corresponding degree. 相似文献