全文获取类型
收费全文 | 1148篇 |
免费 | 27篇 |
国内免费 | 4篇 |
专业分类
化学 | 664篇 |
晶体学 | 23篇 |
力学 | 23篇 |
数学 | 317篇 |
物理学 | 152篇 |
出版年
2022年 | 10篇 |
2021年 | 11篇 |
2020年 | 18篇 |
2019年 | 15篇 |
2018年 | 10篇 |
2016年 | 17篇 |
2015年 | 18篇 |
2014年 | 23篇 |
2013年 | 69篇 |
2012年 | 56篇 |
2011年 | 56篇 |
2010年 | 26篇 |
2009年 | 25篇 |
2008年 | 53篇 |
2007年 | 67篇 |
2006年 | 62篇 |
2005年 | 41篇 |
2004年 | 55篇 |
2003年 | 29篇 |
2002年 | 36篇 |
2001年 | 13篇 |
2000年 | 13篇 |
1999年 | 21篇 |
1998年 | 16篇 |
1997年 | 21篇 |
1996年 | 19篇 |
1994年 | 11篇 |
1993年 | 14篇 |
1992年 | 11篇 |
1991年 | 13篇 |
1990年 | 11篇 |
1989年 | 8篇 |
1988年 | 9篇 |
1986年 | 9篇 |
1985年 | 11篇 |
1984年 | 9篇 |
1982年 | 10篇 |
1981年 | 15篇 |
1980年 | 10篇 |
1979年 | 9篇 |
1977年 | 10篇 |
1975年 | 15篇 |
1974年 | 12篇 |
1973年 | 14篇 |
1972年 | 16篇 |
1971年 | 14篇 |
1970年 | 15篇 |
1969年 | 17篇 |
1968年 | 16篇 |
1967年 | 10篇 |
排序方式: 共有1179条查询结果,搜索用时 15 毫秒
91.
A diastereoselective palladium-catalyzed arylation of 4-substituted cyclohexyl esters has been developed. The reaction proceeds at room temperature in the presence of [(t-Bu3P)PdBr]2 providing products in up to 37:1 dr. 相似文献
92.
Laurence E. Strong Thomas G. Copeland Margaret Darragh Carter Van Waes 《Journal of solution chemistry》1980,9(2):109-128
Conductivities of aqueous solutions ofortho-, meta-, andpara-toluic acids have been measured for the concentration range 0.1–2 millimolar and at 5° intervals from 5 to 100°C. At each temperature pK
a(m) andA
0 have been calculated using the paired ion model recently described by Fuoss. Thermodynamic parameters have been calculated for the ionization of each acid, and Walden products for the anions. Results are discussed in terms of contributions to acidity by enthalpy and entropy changes as well as by hydration of the various solute species. 相似文献
93.
94.
95.
96.
A method to assemble (Z)-enyne esters via palladium-catalyzed cross coupling reactions of enol tosylates is reported. A base-mediated one-pot decarboxylative rearrangement of the enynes to enones is described. The scope of this process is examined. 相似文献
97.
We propose to use block norms to generate nondominated solutions of multiple criteria programs and introduce the new concept of the oblique norm that is specially tailored to handle general problems. We prove the equivalence of finding the properly nondominated solutions of a multiple criteria program and solving its scalarization by means of oblique norms. 相似文献
98.
Reinhardt J. Heuer Robert Thayer Sataloff Kate Emerich Rhonda Rulnick Margaret Baroody Joseph R. Spiegel Gursel Durson John Butler 《Journal of voice》1997,11(1):88-94
This preliminary retrospective study of 19 female patients and 22male patients with unilateral recurrent nerve lesions demonstrated the promise of objective measurements in predicting the need for surgery, the efficacy of voice therapy in ameliorating vocal symptoms, and the effects of therapy in conjunction with surgery. Sixty-eight percent (68%) of the female patients and 64% of the male patients did not elect to have surgery. Outcome satisfaction of nonsurgical and surgical patients appeared to be similar. The data from this study support the importance of preoperative therapy for patients with unilateral vocal fold paralysis. 相似文献
99.
Philip E. Gill Walter Murray Michael A. Saunders John A. Tomlin Margaret H. Wright 《Discrete Optimization》2008,5(2):151-158
We pay homage to George B. Dantzig by describing a less well-known part of his legacy–his early and dedicated championship of the importance of systems optimization in solving complex real-world problems. 相似文献
100.
Nicholle G. A. Bell Adam A. L. Michalchuk John W. T. Blackburn Dr. Margaret C. Graham Dr. Dušan Uhrín 《Angewandte Chemie (International ed. in English)》2015,54(29):8382-8385
Humic substances, the main component of soil organic matter, could form an integral part of green and sustainable solutions to the soil fertility problem. However, their global‐scale application is hindered from both scientific and regulatory perspectives by the lack of understanding of the molecular make‐up of these chromatographically inseparable mixtures containing thousands of molecules. Here we show how multidimensional NMR spectroscopy of isotopically tagged molecules enables structure characterization of humic compounds. We illustrate this approach by identifying major substitution patterns of phenolic aromatic moieties of a peat soil fulvic acid, an operational fraction of humic substances. Our methodology represents a paradigm shift in the use of NMR active tags in structure determination of small molecules in complex mixtures. Unlike previous tagging methodologies that focused on the signals of the tags, we utilize tags to directly probe the identity of the molecules they are attached to. 相似文献