全文获取类型
收费全文 | 4604篇 |
免费 | 142篇 |
国内免费 | 16篇 |
专业分类
化学 | 2859篇 |
晶体学 | 13篇 |
力学 | 237篇 |
数学 | 862篇 |
物理学 | 791篇 |
出版年
2023年 | 42篇 |
2022年 | 78篇 |
2021年 | 136篇 |
2020年 | 110篇 |
2019年 | 98篇 |
2018年 | 84篇 |
2017年 | 93篇 |
2016年 | 189篇 |
2015年 | 147篇 |
2014年 | 142篇 |
2013年 | 254篇 |
2012年 | 269篇 |
2011年 | 295篇 |
2010年 | 179篇 |
2009年 | 153篇 |
2008年 | 284篇 |
2007年 | 271篇 |
2006年 | 228篇 |
2005年 | 243篇 |
2004年 | 167篇 |
2003年 | 160篇 |
2002年 | 117篇 |
2001年 | 52篇 |
2000年 | 49篇 |
1999年 | 44篇 |
1998年 | 34篇 |
1997年 | 31篇 |
1996年 | 52篇 |
1995年 | 44篇 |
1994年 | 38篇 |
1993年 | 35篇 |
1992年 | 26篇 |
1991年 | 27篇 |
1990年 | 28篇 |
1989年 | 30篇 |
1988年 | 29篇 |
1987年 | 40篇 |
1986年 | 23篇 |
1985年 | 39篇 |
1984年 | 43篇 |
1983年 | 19篇 |
1982年 | 23篇 |
1981年 | 28篇 |
1980年 | 29篇 |
1979年 | 23篇 |
1978年 | 18篇 |
1977年 | 29篇 |
1975年 | 15篇 |
1974年 | 13篇 |
1858年 | 11篇 |
排序方式: 共有4762条查询结果,搜索用时 31 毫秒
1.
Journal of Optimization Theory and Applications - Pollution management models of Shallow Lake type identify a well-known class of infinite horizon optimal control problems, characterized by the... 相似文献
2.
3.
Numerical Algorithms - We introduce a modulus-based formulation for vertical linear complementarity problems (VLCPs) with an arbitrary number ? of matrices. This formulation can be used to... 相似文献
4.
Francesco Segatta David M. Rogers Naomi T. Dyer Ellen E. Guest Zhuo Li Hainam Do Artur Nenov Marco Garavelli Jonathan D. Hirst 《Molecules (Basel, Switzerland)》2021,26(2)
A fully quantitative theory of the relationship between protein conformation and optical spectroscopy would facilitate deeper insights into biophysical and simulation studies of protein dynamics and folding. In contrast to intense bands in the far-ultraviolet, near-UV bands are much weaker and have been challenging to compute theoretically. We report some advances in the accuracy of calculations in the near-UV, which were realised through the consideration of the vibrational structure of the electronic transitions of aromatic side chains. 相似文献
5.
Vito Gigante Laura Aliotta Maria Beatrice Coltelli Patrizia Cinelli Luigi Botta Francesco Paolo La Mantia Andrea Lazzeri 《Journal of polymer science. Part A, Polymer chemistry》2020,58(23):3264-3282
The development of biodegradable materials for tailored applications, particularly in the field of polymeric films and sheets, is a challenging technological goal as well as a contribution to help protect the environment. Poly(lactic) acid (PLA) is a promising substitute for several oil-based polymers; however, to overcome its thermal and mechanical drawbacks, researchers have developed solutions such as blending PLA with polybutylene adipate terephthalate (PBAT), which is capable of increasing the ductility of the final material. In this study, PLA/PBAT binary blends, with minimum possible content of nonrenewable materials, were examined from processing, thermal, morphological, and rheological perspective. An optimized PLA/PBAT ratio was chosen as the polymeric basis to obtain a biodegradable formulation by adding a biobased plasticizer and appropriate fillers to produce a micrometer film with tailored flexibility and tear resistance. The processing technology involved flat-die extrusion, followed by calendering. The tearing resistance of the produced film was investigated, and the results were compared with literature data. A study on the essential work of fracture was implemented to explore the mode III out-of-plane fracture resistance starting from a trouser tear test. 相似文献
6.
7.
Nicolò Giovannelli Giuseppe Rao Calogero Vetro 《Rendiconti del Circolo Matematico di Palermo》2005,54(3):443-450
In this paper we consider a definition of essentialK-variation for real functions which gives information on the absolute integrability of its approximate derivate on a measurable
set. 相似文献
8.
We study the real valued functions having a primitive with respect to the oscillation or a primitive with respect to the oscillation
up to anegligible set.
Supported by MURST of Italy. 相似文献
Supported by MURST of Italy. 相似文献
9.
The concept of strong interactions need not be limited to the sector of physics taken by QCD. While this domain is investigated by RHIC, LHC will be able to probe potential new strong interactions simultaneously: Finding the precise mechanism for electroweak symmetry breaking is one of the prime problems of physics. Intricately linked to this point is the question after the true nature or even the existence of the Higgs boson. Here, we present stronly interacting theories providing an explanation for the hierarchy problem and leading to a light composite Higgs boson, favoured by experimental data. Our variation of the standard model is consistent with precision data. We achieve this accordance by using technifermions in a higher representation of their gauge group. Anomaly conditions require at least one extra lepton family for some of the theories whereby they contain a natural dark matter candidate. We can accurately determine the masses of said leptons from experimental data. 相似文献
10.
Ohne Zusammenfassung 相似文献