全文获取类型
收费全文 | 340篇 |
免费 | 35篇 |
国内免费 | 60篇 |
学科分类
数理化 | 435篇 |
出版年
2023年 | 5篇 |
2022年 | 15篇 |
2021年 | 10篇 |
2020年 | 10篇 |
2019年 | 10篇 |
2018年 | 17篇 |
2017年 | 15篇 |
2016年 | 15篇 |
2015年 | 12篇 |
2014年 | 20篇 |
2013年 | 32篇 |
2012年 | 24篇 |
2011年 | 23篇 |
2010年 | 17篇 |
2009年 | 23篇 |
2008年 | 20篇 |
2007年 | 22篇 |
2006年 | 14篇 |
2005年 | 15篇 |
2004年 | 15篇 |
2003年 | 15篇 |
2002年 | 17篇 |
2001年 | 9篇 |
2000年 | 7篇 |
1999年 | 4篇 |
1998年 | 2篇 |
1997年 | 2篇 |
1996年 | 4篇 |
1995年 | 5篇 |
1994年 | 3篇 |
1993年 | 2篇 |
1991年 | 3篇 |
1990年 | 2篇 |
1989年 | 3篇 |
1988年 | 8篇 |
1987年 | 1篇 |
1986年 | 5篇 |
1985年 | 3篇 |
1984年 | 1篇 |
1983年 | 3篇 |
1981年 | 1篇 |
1979年 | 1篇 |
排序方式: 共有435条查询结果,搜索用时 15 毫秒
91.
92.
93.
城市下水污泥和煤/LPG在循环流化床上的混烧试验研究 总被引:2,自引:0,他引:2
在高6000 mm、直径300mm的循环流化床上进行了含水率为79%的湿污泥与煤/石油液化气(LPG)的混烧试验。试验结果表明:无论用煤还是LPG作为辅助燃料,试验都能在设定的工况条件下稳定运行;向炉内加入石灰石的量达到钙硫摩尔比为3.4∶1时,二氧化硫和氯化氢的排放达标,脱硫效率和脱氯效率分别为75%和94%;在试验中, 烟气中NOx排放、烟气中汞含量和二恶英类排放都不超标;试验产生的飞灰含碳量低,飞灰中痕量元素的浸出毒性不超标;计算表明,如果利用余热干燥污泥和预热空气可有效地减少辅助燃料的消耗量。 相似文献
94.
In this study, rigid 4,4'-diglycidyl(3,3',5,5'-tetramethylbiphenyl) epoxy(TMBP)-based composites were developed by the incorporation of varying percentages of commercial hollow glass microspheres(HGMs, QH-450) into the TMBP resin used for electronic packaging. The thermal and mechanical properties as well as the morphology of all the composites were characterized, and dielectric properties were characterized by advanced analytical techniques. The results reveal that a series of TMBP/QH-450 composites exhibits higher initial degradation temperatures(Td,5%>300℃), and the residual char and glass transition temperature were clearly improved with QH-450 loading. In addition, all epoxy composites exhibited a lower dielectric constant ranging from 3.74 to 3.06 at 1.2 MHz because the lower dielectric properties of the inert gas used as the core of the QH-450 decreased molecule polarity. Hence, this developed TMBP/QH450 system demonstrates potential applications in electronic packaging. 相似文献
95.
96.
The kinetics of oxidation of nitrilotris(methylenephosphonato)chromium(III), CrIIINTMP, by periodate to yield CrVI have been studied spectrophotometrically over the 5.80–6.85 pH range at 22–33 °C. The reaction rate, which is first-order with respect to [CrIIINTMP] and [IO–
4] and inversely dependent on [H+], obeys the rate law:-d[CrIIINTMP/dt=kKKh[IO-
4] [CrIII]T/Kh+ [H+] +KKh[IO-
4] The values of the intramolecular electron transfer, k, and the formation constant of the intermediate complex, K, were determined at various temperatures. The hydrolysis constant for CrIIINTMP, K
h
, was determined spectrophotometrically and is in agreement with the value estimated from the kinetic data. The activation parameters were calculated from the temperature dependence of the specific rate constants. A mechanism is proposed in which the hydroxo complex, [CrHNTMP(OH)]3–, is the reactive species. The results support a mechanism where intramolecular electron transfer is the rate-determining step. 相似文献
97.
J. L. Bailly S. Banerjee F. Bruyant B. Buschbeck C. Caso H. Dibon B. Epp A. Ferrando F. Fontanelli T. Gemesy A. Gurtu R. Hamatsu Ph. Herquet T. Hirose J. Hrubec Yu. Ivanysherkov E. P. Kistenev N. Khalatyan S. Kitamura T. Kreuzberger V. Kubik P. Lipa P. K. Malhotra M. Markytan I. S. Mittra L. Montanet G. Neuhofer G. Pinter P. Porth R. Raghavan T. Rodrigo J. B. Singh S. Squarcia U. Trevisan K. Takahashi L. A. tikhonova T. Yamagata G. Zholobov J. Zoll S. A. Zotkin NA EHS - RCBC Collaboration 《Zeitschrift fur Physik C Particles and Fields》1988,40(1):13-24
Two particle correlations of hadrons produced in 360 GeV/cpp interactions are investigated in the transverse plane and in rapidity. The data were obtained at the European hybrid spectrometer equipped with a rapid cycling bubble chamber. The observed transverse and rapidity correlations are compared with the one string LUND-and a two string dual parton-model. These models predict in general stronger correlations in the transverse plane and much weaker correlations in rapidity than found in the data. The LUND-FRITIOF-and multichain dual parton models provide a better reproduction of the data, although the agreement is not yet satisfactory. Only the UA5 cluster model GENCL shows agreement with the data. 相似文献
98.
在氮气保护下利用共沉淀方法成功地合成了零价铁无定形磷酸钙复合物(Fe0/ACP复合物),并采用XRD、EDAX和FTIR对产物进行了表征。同时通过SEM和TEM分析可知所合成材料的粒径为300 nm左右。磁滞回线表明在磁场中可以将该复合物从非磁性材料中分离出来。氮气吸附脱附曲线表明所合成材料具有吸附性能。此外所合成Fe0/ACP复合物被用来吸附CdTe量子点,并采用二级动力学方程对吸附过程进行了分析。吸附产物采用XRD、FTIR、荧光和磁滞回线进行了表征,结果表明该吸附产物不仅具有磁性,而且具有很好的荧光性质。 相似文献
99.
Recent advances in host–guest chemistry have significantly influenced the construction of supramolecular soft biomaterials. The highly selective and non‐covalent interactions provide vast possibilities of manipulating supramolecular self‐assemblies at the molecular level, allowing a rational design to control the sizes and morphologies of the resultant objects as carrier vehicles in a delivery system. In this Focus Review, the most recent developments of supramolecular self‐assemblies through host–guest inclusion, including nanoparticles, micelles, vesicles, hydrogels, and various stimuli‐responsive morphology transition materials are presented. These sophisticated materials with diverse functions, oriented towards therapeutic agent delivery, are further summarized into several active domains in the areas of drug delivery, gene delivery, co‐delivery and site‐specific targeting deliveries. Finally, the possible strategies for future design of multifunctional delivery carriers by combining host–guest chemistry with biological interface science are proposed. 相似文献
100.
任播服务在IPv6[1]中定义为一种标准的网络服务,它获得了越来越广泛的应用,已成为一种十分重要的网络服务.其研究虽已获得不少结果。但有关其服务质量之严格的数学分析并不多见.本文对[2,3][所建立的任播网络系统(ED,1)。(WD/D H,1),和(WD/D B,1)进行了平稳分析.给出了这些系统在平稳条件下录用概率和拒绝概率的解析表达式. 相似文献