全文获取类型
收费全文 | 3271篇 |
免费 | 120篇 |
国内免费 | 18篇 |
学科分类
工业技术 | 3409篇 |
出版年
2023年 | 17篇 |
2022年 | 23篇 |
2021年 | 62篇 |
2020年 | 53篇 |
2019年 | 47篇 |
2018年 | 72篇 |
2017年 | 55篇 |
2016年 | 74篇 |
2015年 | 53篇 |
2014年 | 72篇 |
2013年 | 187篇 |
2012年 | 112篇 |
2011年 | 155篇 |
2010年 | 139篇 |
2009年 | 160篇 |
2008年 | 127篇 |
2007年 | 124篇 |
2006年 | 106篇 |
2005年 | 91篇 |
2004年 | 107篇 |
2003年 | 86篇 |
2002年 | 84篇 |
2001年 | 77篇 |
2000年 | 66篇 |
1999年 | 75篇 |
1998年 | 119篇 |
1997年 | 76篇 |
1996年 | 69篇 |
1995年 | 53篇 |
1994年 | 59篇 |
1993年 | 67篇 |
1992年 | 60篇 |
1991年 | 50篇 |
1990年 | 46篇 |
1989年 | 55篇 |
1988年 | 44篇 |
1987年 | 31篇 |
1986年 | 37篇 |
1985年 | 40篇 |
1984年 | 40篇 |
1983年 | 38篇 |
1982年 | 23篇 |
1981年 | 25篇 |
1980年 | 30篇 |
1979年 | 15篇 |
1978年 | 21篇 |
1977年 | 27篇 |
1976年 | 32篇 |
1974年 | 19篇 |
1973年 | 24篇 |
排序方式: 共有3409条查询结果,搜索用时 31 毫秒
31.
32.
33.
Wide band gap a-SiOx:H films have been prepared by the photochemical decomposition of a SiH4, CO2 and H2 gas mixture. Deposition parameters namely the CO2 to SiH4 gas flow ratio, H2 dilution and chamber pressure were optimized in order to achieve highly photoconducting (1 × 10-6 S cm-1) films with an optical gap of 1.99 eV. The optical gap was found to increase with an increase in the CO2 to SiH4 flow ratio. A decrease in the photoconductivity, refractive index, spin g-value and a simultaneous increase in the spin density are attributed to an incorporation of oxygen into the films. Upon hydrogen
dilution the photoconductivity of a-SiOx:H films was observed to improve along with an increase of the optical gap. The spin density of a-SiOx:H films was of the order of 1017 cm-9. The optoelectronic properties of the films have been correlated with the bonding configurations in the film, deposition
parameters and the growth kinetics.
This revised version was published online in November 2006 with corrections to the Cover Date. 相似文献
34.
35.
A modified CIECAM02 colour appearance model, named CIECAM02‐m2, is proposed to enable CIECAM02 to predict the simultaneous contrast effect. The structure of the CIECAM02‐m2 is a development from CIECAM02, and contains two different procedures for modifying the reference white; one is for lightness and the other is for hue. The model was tested using a data set accumulated in this study and the LUTCHI data. The CV values for three colour attributes between predictions and experimental data were used to evaluate the accuracy of the model. The low CV values obtained show the performance of the CIECAM02‐m2 model to predict the simultaneous contrast effect satisfactorily. © 2007 Wiley Periodicals, Inc. Col Res Appl, 32, 121 – 129, 2007 相似文献
36.
Ray Marsili 《Journal of dairy science》1985,68(12):3155-3161
The concentrations of several chemical metabolites in Cheddar cheese were monitored by various chromatographic techniques during the aging process to learn which metabolites were the best predictors of the glycolytic, lipolytic, and proteolytic age of the cheese. Pyruvic, lactic, acetic, and propionic acids were measured by ion-exchange high performance liquid chromatography; acetone, 2-butanone, ethanol, 2-pentanone, 2-butanol, and n-propanol were monitored by headspace gas chromatography; free fatty acids were quantitated (without derivatization) by gas chromatography; and free amino acids were determined as their o-phthaldehye derivatives by high performance liquid chromatography.The best predictors of the glycolytic age were propionic acid and acetic acid; the best predictors of lipolysis were the free fatty acids C10, C12, C14, and C16; and the best predictors of proteolysis were the free amino acids leucine, methionine, and glutamic acid. The volatile metabolites determined by headspace gas chromatography were not good indicators of aging; however, they did provide useful information related to flavor problems.Cheddar cheese aged at elevated temperatures produced propionic acid, acetic acid, and free amino acids at significantly faster rates than the other chemicals that were monitored. 相似文献
37.
38.
39.
40.
Microsystem Technologies - A physics-based Quantum-Modified CLassical Drift–Diffusion (QMCLDD) non-linear mathematical model has been developed for design and characterisation of GaN/AlGaN... 相似文献