全文获取类型
收费全文 | 2357篇 |
免费 | 358篇 |
国内免费 | 192篇 |
专业分类
化学 | 1180篇 |
晶体学 | 11篇 |
力学 | 99篇 |
综合类 | 29篇 |
数学 | 220篇 |
物理学 | 746篇 |
综合类 | 622篇 |
出版年
2024年 | 14篇 |
2023年 | 49篇 |
2022年 | 78篇 |
2021年 | 75篇 |
2020年 | 109篇 |
2019年 | 94篇 |
2018年 | 71篇 |
2017年 | 55篇 |
2016年 | 85篇 |
2015年 | 87篇 |
2014年 | 103篇 |
2013年 | 135篇 |
2012年 | 166篇 |
2011年 | 173篇 |
2010年 | 96篇 |
2009年 | 125篇 |
2008年 | 107篇 |
2007年 | 114篇 |
2006年 | 112篇 |
2005年 | 91篇 |
2004年 | 93篇 |
2003年 | 69篇 |
2002年 | 56篇 |
2001年 | 37篇 |
2000年 | 42篇 |
1999年 | 62篇 |
1998年 | 62篇 |
1997年 | 56篇 |
1996年 | 64篇 |
1995年 | 64篇 |
1994年 | 47篇 |
1993年 | 47篇 |
1992年 | 40篇 |
1991年 | 44篇 |
1990年 | 36篇 |
1989年 | 40篇 |
1988年 | 33篇 |
1987年 | 22篇 |
1986年 | 13篇 |
1985年 | 10篇 |
1984年 | 2篇 |
1983年 | 3篇 |
1982年 | 2篇 |
1981年 | 2篇 |
1980年 | 4篇 |
1979年 | 4篇 |
1978年 | 2篇 |
1976年 | 4篇 |
1973年 | 4篇 |
1930年 | 1篇 |
排序方式: 共有2907条查询结果,搜索用时 15 毫秒
1.
Tianyu Gong Longhai Guo Jun Ye Lifan He Teng Qiu Xiaoyu Li 《Journal of polymer science. Part A, Polymer chemistry》2021,59(16):1807-1820
The implementation of covalent adaptable networks (CANs) in general resin system is becoming attractive. In this work, we propose a simple post-curing strategy based on the core-shell structured acrylate latex for the achievement on both the improved general performance and the CANs characteristics in latex films. The building to the CANs was relied on the introduction of 4,4′-diaminophenyl disulfide as the curing agent, which cured the acetoacetoxy decorated shell polymer through the ketoamine reaction. The metathesis reaction of aromatic disulfides in the crosslinking segments enabled the thermally induced dynamic behavior of the network as revealed in the stress relaxation tests by comparison with other diamine crosslinking agents without the incorporation of disulfide. The synergism of the dynamic crosslinking of the shell polymer and static crosslinking in the core polymer contributed to the improved mechanical strength (15 MPa, strain% = 250%) and the suppressed water adsorption (~1% in 24 h of soaking) of the latex film, which exhibited above 90% of recovery in both strength and strain from a cut-off film damage within 1 h at 80°C. Moreover, the cured latex film could be recycled, and 75% of the mechanical performance was regained after three fragmentation-hot-pressing cycles. These, in addition with the feasible and environmental friendly characteristics, suggest a sustainable paradigm toward the smart thermosetting latex polymers. 相似文献
2.
3.
4.
A rapid method had been used for comparative study on Artemisia halodendron Turcz. and its two related plants by gas phase-mass spectrometry (GC-MS). The comparison of the volatile oils obtained in three plants by GC-MS were similar in 20 compositions. However, n-Hexadecanoic acid (10.40%), Biphenyl (7.867%) and 9,12-Octadecadienoic acid (7.25%) were the predominant in the volatile oils of A. halodendron Turcz., whereas these constituents did not exist in the other two plants. And the study investigated the effect of three plants against CCl4-induced hepatotoxicity in mice. 70% ethanol extracts of A. halodendron Turcz. showed weaker protective effect than the other two plants. It suggested that they provide a basis for the identification of the A. halodendron Turcz. from the other two plants and the ethanol extract from three plants exerted a protecting effect against hepatotoxicity. 相似文献
5.
Ji-Dong Lou Chun-Ling Gao Li Li Zhi-Gang Fang 《Monatshefte für Chemie / Chemical Monthly》2006,41(10):1071-1074
A new procedure for the selective oxidation of alcohols to the corresponding aldehydes and ketones with potassium permanganate
supported on aluminum silicate at room temperature under solvent-free conditions and shaking is reported. 相似文献
6.
The theory of tree-growing (RECPAM approach) is developed for outcome variables which are distributed as the canonical exponential family. The general RECPAM approach (consisting of three steps: recursive partition, pruning and amalgamation), is reviewed. This is seen as constructing a partition with maximal information content about a parameter to be predicted, followed by simplification by the elimination of ‘negligible’ information. The measure of information is defined for an exponential family outcome as a deviance difference, and appropriate modifications of pruning and amalgamation rules are discussed. It is further shown how the proposed approach makes it possible to develop tree-growing for situations usually treated by generalized linear models (GLIM). In particular, Poisson and logistic regression can be tree-structured. Moreover, censored survival data can be treated, as in GLIM, by observing a formal equivalence of the likelihood under random censoring and an appropriate Poisson model. Three examples are given of application to Poisson, binary and censored survival data. 相似文献
7.
8.
A new reagent, potassium permanganate adsorbed on aluminum silicate, suitable for the oxidation of primary and secondary alcohols to the corresponding carbonyl compounds is described. 相似文献
9.
10.
对美国HONEYWELL公司S9000DCS系统软件和系统数据进行了结构分析,着重研究并总结出S9000历史数据库的数据结构,开发出TSR型实用软件,实现了S9000汉化报表生成,同时也拓宽了S9000在工业生产中的实际应用范围。 相似文献