全文获取类型
收费全文 | 1679篇 |
免费 | 77篇 |
国内免费 | 8篇 |
专业分类
化学 | 1317篇 |
晶体学 | 6篇 |
力学 | 26篇 |
数学 | 182篇 |
物理学 | 233篇 |
出版年
2023年 | 14篇 |
2022年 | 10篇 |
2021年 | 28篇 |
2020年 | 41篇 |
2019年 | 35篇 |
2018年 | 16篇 |
2017年 | 12篇 |
2016年 | 70篇 |
2015年 | 55篇 |
2014年 | 67篇 |
2013年 | 84篇 |
2012年 | 131篇 |
2011年 | 119篇 |
2010年 | 74篇 |
2009年 | 61篇 |
2008年 | 99篇 |
2007年 | 87篇 |
2006年 | 102篇 |
2005年 | 85篇 |
2004年 | 99篇 |
2003年 | 72篇 |
2002年 | 56篇 |
2001年 | 38篇 |
2000年 | 27篇 |
1999年 | 21篇 |
1998年 | 17篇 |
1997年 | 17篇 |
1996年 | 32篇 |
1995年 | 18篇 |
1994年 | 23篇 |
1993年 | 9篇 |
1992年 | 7篇 |
1991年 | 7篇 |
1988年 | 3篇 |
1986年 | 3篇 |
1985年 | 5篇 |
1983年 | 3篇 |
1981年 | 6篇 |
1980年 | 4篇 |
1979年 | 8篇 |
1978年 | 7篇 |
1976年 | 6篇 |
1974年 | 4篇 |
1973年 | 6篇 |
1971年 | 4篇 |
1970年 | 4篇 |
1969年 | 3篇 |
1936年 | 7篇 |
1933年 | 4篇 |
1901年 | 3篇 |
排序方式: 共有1764条查询结果,搜索用时 31 毫秒
1.
2.
Kamali Ahangar Ehsan Izanlu Morteza Dolati Khakhian Shabnam Mohamad Abdulmajeed A. Bach Quang-Vu 《Journal of Thermal Analysis and Calorimetry》2021,144(6):2525-2541
Journal of Thermal Analysis and Calorimetry - Thermal microscale gas flow was simulated into a coplanar microchannel was simulated at a broad range of Knudsen numbers. Attempts were made to improve... 相似文献
3.
4.
Thorsten Brand Kyle Ratinac Jeffrey V. Castro Robert G. Gilbert 《Journal of polymer science. Part A, Polymer chemistry》2004,42(22):5706-5713
A method was developed for free‐radical polymerization in the confines of a hollow latex particle. Hollow particles were prepared via the dynamic swelling method from polystyrene seed and divinylbenzene and had hollows of 500–1000 nm. So that these hollow poly(divinylbenzene) particles could function as submicrometer reactors, the particles were filled with a monomer (N‐isopropylacrylamide) via the dispersion of the dried particles in the molten monomer. The monomer that was not contained in the hollows was removed by washing and gentle abrasion. Free‐radical polymerization was then initiated by γ radiolysis in the solid state. Transmission electron microscopy showed that poly(N‐isopropylacrylamide) formed in the hollow interior of the particles, which functioned as submicrometer reactors. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5706–5713, 2004 相似文献
5.
Thorsten Hamann Erin Osborne Heather L. Youngs Julie Misson Laurent Nussaume Chris Somerville 《Cellulose (London, England)》2004,11(3-4):279-286
We have used Affymetrix gene chips to measure the expression of 10 CESA and 29 CSL genes of Arabidopsis in different developmental stages or organs. These measurements reveal that many of the genes exhibit different levels of expression in the various organs. While several CESA genes are highly expressed in all the tissues examined, very few CSL genes approach such high levels of expression. This suggests that the CSL genes either encode enzymes for the synthesis of minor components of cell walls or are expressed only in specific cell types. The expression data also highlights the potential importance of the CESA genes for primary and secondary cell wall formation during different developmental stages and in the different organs examined. 相似文献
6.
Yuri M. Boiko Anders Bach Jørgen Lyngaae-Jørgensen 《Journal of Polymer Science.Polymer Physics》2004,42(10):1861-1867
Films of amorphous polystyrene (PS) with a weight-average molecular weight (Mw) of 225 × 103 g/mol were bonded in a T-peel test geometry, and the fracture energy (G) of a PS/PS interface was measured at the ambient temperature as a function of the healing time (th) and healing temperature (Th). G was found to develop with (th)1/2 at Th = Tg-bulk − 33 °C (where Tg-bulk is the glass-transition temperature of the bulk sample), and log G was found to develop with 1/Th at Tg-bulk − 43 °C ≤ Th ≤ Tg-bulk − 23 °C. The smallest measured value of G = 1.4 J/m2 was at least one order of magnitude larger than the work of adhesion required to reversibly separate the PS surfaces. These three observations indicated that the development of G at the PS/PS interface in the temperature range investigated (<Tg-bulk) was controlled by the diffusion of chain segments feasible above the glass-transition temperature of the interfacial layer, in agreement with our previous findings for fracture stress development at several polymer/polymer interfaces well below Tg-bulk. Close values of G = 8–9 J/m2 were measured for the symmetric interfaces of polydisperse PS [Mw = 225 × 103, weight-average molecular weight/number-average molecular weight (Mw/Mn) = 3] and monodisperse PS (Mw = 200 × 103, Mw/Mn = 1.04) after healing at Th = Tg-bulk − 33 °C for 24 h. This implies that the self-bonding of high-molecular-weight PS at such relatively low temperatures is not governed by polydispersity. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1861–1867, 2004 相似文献
7.
8.
Andrew Bach Xinglong Jiang Joseph Mckenna Kapa Prasad Oljan Repic Wen‐Chung Shieh 《Journal of heterocyclic chemistry》2004,41(4):637-640
An efficient approach has been developed for the synthesis of an isofervenulin analogue 1 employing a one‐pot condensation‐substitution reaction of a chlorocarboethoxytriazine (electrophile) with a urea (nucleophile). The resulting cyclization reaction resulted in the synthesis of a pyrimido‐heterocycle in good yield in either acidic or basic media. The former was assisted by utilizing trimethylsilyl chloride. 相似文献
9.
Rafał Bocian Thorsten Holm Andrzej Skowroński 《Central European Journal of Mathematics》2004,2(1):67-75
Auslander’s representation dimension measures how far a finite dimensional algebra is away from being of finite representation
type. In [1], M. Auslander proved that a finite dimensional algebra A is of finite representation type if and only if the representation dimension of A is at most 2. Recently, R. Rouquier proved that there are finite dimensional algebras of an arbitrarily large finite representation
dimension. One of the exciting open problems is to show that all finite dimensional algebras of tame representation type have
representation dimension at most 3. We prove that this is true for all domestic weakly symmetric algebras over algebraically
closed fields having simply connected Galois coverings. 相似文献
10.