全文获取类型
收费全文 | 243篇 |
免费 | 3篇 |
国内免费 | 1篇 |
专业分类
化学 | 115篇 |
晶体学 | 7篇 |
力学 | 7篇 |
数学 | 17篇 |
物理学 | 101篇 |
出版年
2022年 | 3篇 |
2021年 | 5篇 |
2020年 | 5篇 |
2017年 | 4篇 |
2016年 | 8篇 |
2015年 | 7篇 |
2014年 | 10篇 |
2013年 | 19篇 |
2012年 | 11篇 |
2011年 | 13篇 |
2010年 | 8篇 |
2009年 | 6篇 |
2008年 | 10篇 |
2007年 | 10篇 |
2006年 | 6篇 |
2005年 | 8篇 |
2004年 | 3篇 |
2003年 | 2篇 |
2002年 | 4篇 |
2001年 | 4篇 |
2000年 | 2篇 |
1996年 | 2篇 |
1995年 | 4篇 |
1994年 | 3篇 |
1993年 | 4篇 |
1990年 | 2篇 |
1988年 | 2篇 |
1985年 | 3篇 |
1984年 | 7篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1981年 | 3篇 |
1980年 | 2篇 |
1979年 | 12篇 |
1978年 | 3篇 |
1977年 | 2篇 |
1976年 | 3篇 |
1975年 | 3篇 |
1974年 | 3篇 |
1973年 | 6篇 |
1972年 | 2篇 |
1966年 | 4篇 |
1963年 | 2篇 |
1962年 | 2篇 |
1960年 | 2篇 |
1955年 | 2篇 |
1947年 | 1篇 |
1941年 | 1篇 |
1926年 | 1篇 |
1925年 | 1篇 |
排序方式: 共有247条查询结果,搜索用时 46 毫秒
51.
The results of photoconductivity (PC), photoluminescence (PL), optical absorption spectra, XRD and SEM studies are presented
for (Cd0.95-Pb0.05)S: CdCl2,Ce films prepared by chemical bath deposition technique. PC gains ∼107 are found in doped films. PL emission spectrum is found in red region which is related to 5d to 4f transition in Ce. Films prepared at 60°C show better PC while those prepared at room temperature (RT) show better PL. Optical
absorption studies show reduction in band gap due to addition of PbS. A peak due to Ce is also observed in absorption spectrum.
XRD studies show the presence of both CdS and PbS. SEM studies show presence of microcrystals, cluster of grains along with
some rod type structures. 相似文献
52.
An amino‐acid‐based hydrophobically modified biocompatible copolymer, poly[(sodium N‐acryloyl‐L ‐valinate)‐co‐(N‐octylacrylamide)] was synthesized and characterized. Techniques such as fluorescence probes, DLS, and TEM were used to investigate its aggregation behavior in aqueous solution. The copolymer was observed to form micellar aggregates having diameters in the nanometer range in aqueous solution (pH = 8) through inter‐chain hydrophobic association. This behavior was found to be similar to that of poly[(sodium N‐acryloyl‐L ‐valinate)‐co‐(N‐dodecylacrylamide)]. The compact micellar nanostructures were observed to be stable with respect to changes of pH and temperature. The encapsulation and release of griseofulvin, a hydrophobic model drug, was studied.
53.
Mudigonda K Jukanti R Apte SS Ajjala DR Shrivastava W Kandikere VN Nirogi RV 《Biomedical chromatography : BMC》2006,20(10):1028-1032
A rapid, reliable HPLC method with UV detection (240 nm) was developed and validated for quantitation of saquinavir in mice brain and testis. Saquinavir and the internal standard were isolated from homogenized tissue matrices using liquid-liquid extraction procedure and were then analyzed using an isocratic mobile phase by reversed-phase liquid chromatography. The lower limit of quantification was 50 ng/g for both brain and testis. A linear dynamic range of 50-5000 ng/g for both brain and testis was established. This HPLC method was validated with between-batch precision of 0.5-4.4 and 1.5-5.5% for brain and testis, respectively. The between-batch accuracy was 94.7-105.9% and 97.5-105.0% for brain and testis, respectively. The present method was applied for tissue distribution studies of the novel drug delivery systems of saquinavir in mice. 相似文献
54.
Nirogi RV Kandikere VN Shrivastava W Mudigonda K Datla PV 《Rapid communications in mass spectrometry : RCM》2006,20(8):1225-1230
A simple, sensitive and rapid high-performance liquid chromatography/negative ion electrospray tandem mass spectrometry method was developed and validated for the assay of fluvastatin in human plasma. Following solid-phase extraction, the analytes were separated using an isocratic mobile phase on a reversed-phase column and analyzed by mass spectrometry in the multiple reaction monitoring mode using the respective [M-H]- ions, m/z 410/348 for fluvastatin and m/z 480/418 for the internal standard. The assay exhibited a linear dynamic range of 2-500 ng/mL for fluvastatin in human plasma. The lower limit of quantification was 2 ng/mL with a relative standard deviation of less than 5%. Acceptable precision and accuracy were obtained for concentrations over the standard curve range. A run time of 1.5 min for each sample made it possible to analyze more than 400 human plasma samples per day. The validated method has been successfully used to analyze human plasma samples for application in pharmacokinetic, bioavailability or bioequivalence studies. 相似文献
55.
V. Kumar A.K. Shrivastava Vijeta Jha 《Journal of Physics and Chemistry of Solids》2010,71(11):1513-1520
Using the plasma oscillations theory of solids, simple relations have been proposed for the calculation of bulk modulus (B) and microhardness (H) of group IV, II-VI, III-V, I-III-VI2 and II-IV-V2 semiconductors with tetrahedral structure. We find that B=K1 (?ωp)2.3333 and H=K2 (?ωp)2.3333−K3, where K1, K2 and K3 are the constants. The numerical values of K1, K2 and K3 are respectively, 0.141, 0.036 and 12.895 for group IV, 0.109, 0.0037 and 0.782 for II-VI, 0.125, 0.0202 and 5.743 for III-V, 0.109, 0.0065 and 1.160 for I-III-VI2, and 0.125, 0.0359 and 15.310 for II-IV-V2 semiconductors. The calculated values of B and H are compared with the experimental values and the values reported by different workers. Reasonably good agreement has been obtained between them. 相似文献
56.
The review deals with a novel approach (MNEQT) to nonequilibrium thermodynamics (NEQT) that is based on the concept of internal equilibrium (IEQ) in an enlarged state space involving internal variables as additional state variables. The IEQ macrostates are unique in and have no memory just as EQ macrostates are in the EQ state space . The approach provides a clear strategy to identify the internal variables for any model through several examples. The MNEQT deals directly with system-intrinsic quantities, which are very useful as they fully describe irreversibility. Because of this, MNEQT solves a long-standing problem in NEQT of identifying a unique global temperature T of a system, thus fulfilling Planck’s dream of a global temperature for any system, even if it is not uniform such as when it is driven between two heat baths; T has the conventional interpretation of satisfying the Clausius statement that the exchange macroheatflows from hot to cold, and other sensible criteria expected of a temperature. The concept of the generalized macroheat converts the Clausius inequality for a system in a medium at temperature into the Clausius equality, which also covers macrostates with memory, and follows from the extensivity property. The equality also holds for a NEQ isolated system. The novel approach is extremely useful as it also works when no internal state variables are used to study nonunique macrostates in the EQ state space at the expense of explicit time dependence in the entropy that gives rise to memory effects. To show the usefulness of the novel approach, we give several examples such as irreversible Carnot cycle, friction and Brownian motion, the free expansion, etc. 相似文献
57.
A.M. Samant S. Kailas A. Chatterjee A. Shrivastava A. Navin P. Singh 《The European Physical Journal A - Hadrons and Nuclei》2000,7(1):59-64
The fission fragment angular distributions have been measured for the system 19F +209Bi over a range of bombarding energies from 88.0 MeV to 125.6 MeV. The measured fission fragment anisotropies are in agreement
with the saddle point statistical model calculations in the above energy range. Combining these data with those available
for 11B, 12C, 14N, 16O and 18O +209Bi, 208Pb systems, it is concluded that the spherical target plus projectile systems behave “normal” from near- to above – barrier
energies. This observation is in contrast to the “anomalous” anisotropies exhibited by the deformed actinide target – projectile
systems at near – barrier energies.
Received: 5 May 1999 / Revised version: 25 July 1999 相似文献
58.
JPC – Journal of Planar Chromatography – Modern TLC - The phytochemical fingerprint profile of ammoniacum gum (from Dorema ammoniacum) was defined by subjecting different extracts of... 相似文献
59.
60.