全文获取类型
收费全文 | 1853篇 |
免费 | 38篇 |
国内免费 | 9篇 |
专业分类
化学 | 1357篇 |
晶体学 | 34篇 |
力学 | 44篇 |
数学 | 239篇 |
物理学 | 226篇 |
出版年
2023年 | 4篇 |
2021年 | 16篇 |
2020年 | 24篇 |
2019年 | 20篇 |
2018年 | 14篇 |
2017年 | 18篇 |
2016年 | 39篇 |
2015年 | 24篇 |
2014年 | 47篇 |
2013年 | 98篇 |
2012年 | 105篇 |
2011年 | 138篇 |
2010年 | 54篇 |
2009年 | 61篇 |
2008年 | 124篇 |
2007年 | 130篇 |
2006年 | 141篇 |
2005年 | 112篇 |
2004年 | 87篇 |
2003年 | 81篇 |
2002年 | 83篇 |
2001年 | 37篇 |
2000年 | 18篇 |
1999年 | 23篇 |
1998年 | 22篇 |
1997年 | 27篇 |
1996年 | 20篇 |
1995年 | 33篇 |
1994年 | 37篇 |
1993年 | 12篇 |
1992年 | 19篇 |
1991年 | 17篇 |
1990年 | 16篇 |
1989年 | 18篇 |
1988年 | 16篇 |
1987年 | 9篇 |
1986年 | 10篇 |
1985年 | 19篇 |
1984年 | 12篇 |
1983年 | 13篇 |
1982年 | 16篇 |
1981年 | 8篇 |
1980年 | 15篇 |
1979年 | 8篇 |
1978年 | 13篇 |
1977年 | 7篇 |
1976年 | 4篇 |
1975年 | 6篇 |
1974年 | 9篇 |
1973年 | 5篇 |
排序方式: 共有1900条查询结果,搜索用时 287 毫秒
1.
Susan Baker Lisa Kelchner Barbara Weinrich Linda Lee Paul Willging Robin Cotton Karen Zur 《Journal of voice》2006,20(4):631-641
Laryngotracheal stenosis is defined as a congenital or acquired narrowing of the airway. Congenital causes may include subglottic membranous or cartilaginous narrowing. Acquired causes may include trauma due to prolonged endotracheal or tracheal intubation or laryngotracheal injury. Although advances have been made over the past 30 years in reconstructive surgeries to improve airway patency in these patients, long-term laryngeal function for voice production is not well defined in this population. This review examines causes, symptoms and signs, and methods for diagnosing laryngotracheal stenosis. Surgical management procedures are briefly summarized. The current literature on voice outcomes is summarized. The predominant voice characteristics in the population are presented, although results are challenged by the heterogeneity of voice presentation and paucity of data from instrumental measures. Considerations for subjective and instrumental assessment, measures of quality of life, instrumental methods, and treatment options specific to the needs of this population are discussed. Research strategies to identify long-term outcomes of surgical and behavioral treatments in this population are posed. 相似文献
2.
Benjamin J. K. Evans Susan M. Scott Antony C. Searle 《General Relativity and Gravitation》2002,34(10):1675-1684
We have developed a new tool for numerical work in General Relativity: GRworkbench. We discuss how GRworkbench's implementation of a numerically-amenable analogue to Differential Geometry facilitates the development of robust and chart-independent numerical algorithms. We consider, as an example, geodesic tracing on two charts covering the exterior Schwarzschild space-time. 相似文献
3.
4.
Mark Doyle Susan A. Mulligan Tetsuya Matsuda Gerald M. Pohost 《Magnetic resonance imaging》1992,10(6):887-892
A new “bright blood” strategy, outflow refreshment imaging, is introduced in which a number of overlapping slices are excited in rapid succession. Flowing spins that refresh each overlapped slice portion contribute a bright signal. Additionally, static tissue in each non-overlapped slice portion also yields a bright signal. However, the flow/static contrast is comparable to that produced in inflow refreshment images, and angiograms can be generated by conventional maximum intensity projection processing. The dual ability to visualize angiograms and static tissue images is a major benefit of the strategy. Computer simulations of flow sensitivities and in vivo results are presented which compare the outflow and inflow refreshment imaging strategies. 相似文献
5.
This paper presents an analysis of a portfolio model which can be used to assist a property-liability insurance company in determining the optimal composition of the insurance and investment portfolios. By introducing insurer's threshold risk and relaxing some non-realistic assumptions made in traditional chance constraint insurance and investment portfolio models, we propose a method for an insurer to maximize his return threshold for a given threshold risk level. This proposed model can be used to optimize the composition of underwriting and investment portfolios regarding the insurer's threshold risk level, as well as to generate the efficient frontier by adjusting insurer's threshold risk levels. A numerical example is given based on the industry's aggregated data for a sixteen year period. 相似文献
6.
T. Beda 《Journal of Polymer Science.Polymer Physics》2007,45(13):1713-1732
A constitutive phenomenological model completing the Gent‐Thomas concept is carried out to formulate laws governing the hyperelastic behavior of incompressible rubber materials. It is shown that the phenomenological Gent‐Thomas model (1958) and the constrained chain model (1992) give similar precise results at small to moderate deformation. On the other hand, comparisons of the outcome of the proposed model with that of the molecular model from the combined concepts of Flory‐Erman and Boyce‐Arruda (2000), and with those of the phenomenological models of Ogden (1982), Yeoh‐Fleming (1997), Pucci‐Saccomandi (2002) and Beda (2005) are made. Residual inconveniences raised by attractive continuum models in rubber elasticity literature have been successfully overcome. Results from both the statistical and phenomenological mechanics concepts are compared with the data of some useful classical materials (rubbers of Treloar, Rivlin‐Saunders, Pak‐Flory and Yeoh‐Fleming). The results permit one to see salient equivalence of the two theories for a more reliable prediction of stress‐stretch response for all states of any mode of deformation. A complete and exhaustive analysis of the Mooney plot that combines small and very large extension‐compression has been quite essential in assessing the validity of models. A method of identification of material parameters is presented and data of the simple tension suffice for the determination of the parameter values. It is shown that the ordinary identification procedures, such as the usual least squares, a very much used numerical method in materials investigation, can be unsuitable in some cases of hyperelastic modeling. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 1713–1732, 2007 相似文献
7.
8.
9.
10.