全文获取类型
收费全文 | 1546篇 |
免费 | 78篇 |
国内免费 | 13篇 |
专业分类
化学 | 931篇 |
晶体学 | 24篇 |
力学 | 44篇 |
数学 | 391篇 |
物理学 | 247篇 |
出版年
2023年 | 18篇 |
2022年 | 44篇 |
2021年 | 54篇 |
2020年 | 56篇 |
2019年 | 57篇 |
2018年 | 59篇 |
2017年 | 37篇 |
2016年 | 88篇 |
2015年 | 47篇 |
2014年 | 66篇 |
2013年 | 117篇 |
2012年 | 124篇 |
2011年 | 119篇 |
2010年 | 65篇 |
2009年 | 51篇 |
2008年 | 65篇 |
2007年 | 70篇 |
2006年 | 67篇 |
2005年 | 56篇 |
2004年 | 40篇 |
2003年 | 24篇 |
2002年 | 37篇 |
2001年 | 23篇 |
2000年 | 14篇 |
1999年 | 13篇 |
1998年 | 11篇 |
1997年 | 14篇 |
1996年 | 19篇 |
1995年 | 6篇 |
1994年 | 11篇 |
1993年 | 4篇 |
1992年 | 6篇 |
1991年 | 12篇 |
1990年 | 5篇 |
1989年 | 4篇 |
1988年 | 8篇 |
1987年 | 9篇 |
1986年 | 6篇 |
1985年 | 12篇 |
1984年 | 15篇 |
1983年 | 4篇 |
1982年 | 9篇 |
1981年 | 8篇 |
1980年 | 9篇 |
1979年 | 14篇 |
1978年 | 6篇 |
1976年 | 6篇 |
1975年 | 7篇 |
1973年 | 3篇 |
1969年 | 3篇 |
排序方式: 共有1637条查询结果,搜索用时 15 毫秒
1.
Christian J. -F. Dupraz Patrick Nickels Udo Beierlein Wendy U. Huynh Friedrich C. Simmel 《Superlattices and Microstructures》2003,33(5-6):369
This paper provides an overview of recent research developments in the field of nanoelectronics with organic materials such as carbon nanotubes and DNA-templated nanowires. Carbon nanotubes and gold electrodes are chemically functionalized in order to contact carbon nanotubes by self-assembly. The transport properties of these nanotubes are dominated by charging effects and display clear Coulomb blockade behaviour. A different approach towards nanoscale electronics is based on the molecular recognition properties of biomolecules such as DNA. As an example, DNA is stretched between electrodes using a molecular combing technique. A two-step metallization procedure leads to the formation of highly conductive gold nanowires. 相似文献
2.
This paper proposes a model for the parametric representation of linguistic hedges in Zadeh’s fuzzy logic. In this model each linguistic truth-value, which is generated from a primary term of the linguistic truth variable, is identified by a real number r depending on the primary term. It is shown that the model yields a method of efficiently computing linguistic truth expressions accompanied with a rich algebraic structure of the linguistic truth domain, namely De Morgan algebra. Also, a fuzzy logic based on the parametric representation of linguistic truth-values is introduced. 相似文献
3.
Khanh Le Chau Pham Duc Chinh 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》1991,42(4):614-622
In this paper inequalities for the effective conductivity of isotropic composite materials are derived. These inequalities depend on several coefficients characterizing the microstructure of composites. The obtained coefficients can be exactly calculated for models of a two-component aggregate of multisized, coated ellipsoidal inclusions, packed to fill all space. As a result, new bounds for effective conductivity, considerably narrower than those of Hashin-Shtrikman, are established for such models of composite materials. 相似文献
4.
5.
6.
7.
In this paper we provide an error bound estimate and an implicit multifunction theorem in terms of smooth subdifferentials and abstract subdifferentials. Then, we derive a subdifferential calculus and Fritz–John type necessary optimality conditions for constrained minimization problems. 相似文献
8.
Mitsunori Oda Yosuke Fukuchi Satoshi Ito Nguyen Chung Thanh Shigeyasu Kuroda 《Tetrahedron letters》2007,48(52):9159-9162
Reactions of pyrrolidine with 2 equiv of aldehydes without any catalyst in a pressurized vessel at 140–200 °C yielded 1,3-disubstituted pyrroles. -Branched aldehydes gave fairly good yields of the corresponding products by this method, which provides a facile non-oxidative procedure for synthesizing 1,3-dialkylpyrroles from inexpensive pyrrolidine and aldehydes. 相似文献
9.
Polyazido high-nitrogen compounds: hydrazo- and azo-1,3,5-triazine 总被引:13,自引:0,他引:13
Huynh MH Hiskey MA Hartline EL Montoya DP Gilardi R 《Angewandte Chemie (International ed. in English)》2004,43(37):4924-4928
10.
Nicotine in a smoky indoor air environment can be determined using graphitized carbon black as a solid sorbent in quartz tubes. The temperature stability, high purity, and heat absorption characteristics of the sorbent, as well as the permeability of the quartz tubes to microwaves, enable the thermal desorption by means of microwaves after active sampling. Permeation and dynamic dilution procedures for the generation of nicotine in the vapor phase at low and high concentrations are used to evaluate the performances of the sampler. Tube preparation is described and the microwave desorption temperature is measured. Breakthrough volume is determined to allow sampling at 0.1-1 L/min for definite periods of time. The procedure is tested for the determination of gas and paticulate phase nicotine in sidestream smoke produced in an experimental chamber. 相似文献