全文获取类型
收费全文 | 390篇 |
免费 | 9篇 |
国内免费 | 1篇 |
专业分类
化学 | 210篇 |
晶体学 | 12篇 |
力学 | 4篇 |
数学 | 22篇 |
物理学 | 152篇 |
出版年
2023年 | 4篇 |
2020年 | 11篇 |
2019年 | 15篇 |
2018年 | 7篇 |
2017年 | 10篇 |
2016年 | 14篇 |
2015年 | 5篇 |
2014年 | 6篇 |
2013年 | 24篇 |
2012年 | 14篇 |
2011年 | 19篇 |
2010年 | 9篇 |
2009年 | 11篇 |
2008年 | 8篇 |
2007年 | 17篇 |
2006年 | 15篇 |
2005年 | 16篇 |
2004年 | 12篇 |
2003年 | 12篇 |
2002年 | 7篇 |
2001年 | 3篇 |
2000年 | 3篇 |
1999年 | 9篇 |
1998年 | 7篇 |
1997年 | 3篇 |
1996年 | 4篇 |
1995年 | 5篇 |
1994年 | 6篇 |
1993年 | 5篇 |
1992年 | 8篇 |
1991年 | 6篇 |
1990年 | 6篇 |
1989年 | 3篇 |
1988年 | 7篇 |
1987年 | 4篇 |
1986年 | 6篇 |
1985年 | 10篇 |
1984年 | 12篇 |
1983年 | 5篇 |
1982年 | 2篇 |
1981年 | 10篇 |
1980年 | 4篇 |
1979年 | 3篇 |
1977年 | 7篇 |
1974年 | 3篇 |
1973年 | 4篇 |
1972年 | 2篇 |
1971年 | 5篇 |
1955年 | 2篇 |
1954年 | 2篇 |
排序方式: 共有400条查询结果,搜索用时 31 毫秒
31.
We present a highly selective and sensitive method for the determination of cysteine (Cys) and related aminothiols that play important roles in health and disease. The key step in the analysis is treatment with 1,1′-thiocarbonyldiimidazole (TCDI) that rapidly and quantitatively reacts with both the amino and thiol groups to form stable cyclic dithiocarbamates with intense UV absorption. Cys, homocysteine (hCys), and cysteinylglycine in plasma (75 μl), urine (100 μl), or cerebrospinal fluid (100–500 μl) were determined by separating and measuring their cyclic derivatives by a high performance liquid chromatograph (HPLC) connected to a UV detector. The chromatograms obtained using TCDI contained fewer and better-resolved peaks than those produced by less selective reagents used previously. Using chemically similar 2-methylcysteine as the internal standard, high repeatability (variation of less than 5%) and adequate sensitivity to detect small increments (10–20%) in the concentrations of cysteinylglycine and hCys were achieved. The HPLC method can also be modified to measure
-penicillamine (greater than 0.8 μM) in plasma (50 μl) providing a potential method to monitor plasma levels of this drug in patients. 相似文献
32.
M. Sainath K. Venkataramaniah P. C. Sood 《The European Physical Journal A - Hadrons and Nuclei》2007,31(2):135-140
Low-lying two-quasiparticle bandhead energies for the Z = 99 odd-odd nucleus 254Es are evaluated using a simple phenomenological model with the inclusion of the residual p-n interaction. Configurations of the intrinsic levels directly fed in 254Es from the parent 258Md are discussed in the light of this model. Our analysis predicts the occurrence of ten K≤5 bandheads in 254Es with excitation energies E
x≤300keV. Structures of these as yet unidentified low-lying intrinsic levels and their expected locations are discussed in
the light of available experimental information. 相似文献
33.
Surajit Saha Surjeet Singh R. Suryanarayanan A.K. Sood 《Journal of solid state chemistry》2011,184(8):2204-2208
Here we report a temperature-dependent Raman study of the pyrochlore “dynamic spin-ice” compound Pr2Sn2O7 and compare the results with its non-pyrochlore (monoclinic) counterpart Pr2Ti2O7. In addition to phonon modes, we observe two bands associated with electronic Raman scattering involving crystal field transitions in Pr2Sn2O7 at ∼135 and 460 cm−1 which couple strongly to phonons. Anomalous temperature dependence of phonon frequencies that are observed in pyrochlore Pr2Sn2O7 are absent in monoclinic Pr2Ti2O7. This, therefore, confirms that the strong phonon-phonon anharmonic interactions, responsible for the temperature-dependent anomalous behavior of phonons, arise due to the inherent vacant sites in the pyrochlore structure. 相似文献
34.
Raymond K. Sheline B. Singh P. C. Sood S. Y. Chu 《Czechoslovak Journal of Physics》1999,49(7):1047-1066
Energies of the first 2+, 3− and 4+ states of even-even nuclei are plotted against proton and neutron number. Using this systematics, shell effects and the corresponding
quadrupole and hexadecapole collectivity and deformation effects are compared and contrasted. Also, the correspondingB(E2),B(E3) andB(E4) values are plotted against neutron number and their very different systematics compared. Among the new results are the
presence of hexadecapole collectivity at the 82 proton and neutron closed shells and the presence of the maximum values ofB(E4) at neutron numbers 10, 90–92 and 140–146. Finally, the systematics of the hexadecapole (K=4+) vibrations is compared with that of the quadrupole (K=2+) gamma vibrations in the quadrupole deformed rare earth region.
This research has been supported by the National Sciences and Engineering Research Council of Canada at McMaster University
and by the Department of Atomic Energy, Government of India, at Banaras Hindu University. 相似文献
35.
The total attenuation cross-sections in elements 6?Z?82 forK α andK β groups of lines of elements Zr, Sn and Ba andL l ,L α,L β andL γ groups of lines of the elements Au, Pb, Th and U have been measured. The experimentally measured attenuation cross-sections have been found in good agreement with the theoretical estimates. 相似文献
36.
Sathishkumar Arumugam Kapil Bandil Peter Proksch Kalaiselvam Murugiyan Mausumi Bharadwaj 《Applied biochemistry and biotechnology》2017,182(2):697-707
TNF-related apoptosis-inducing ligand (TRAIL) is an anticancer agent, which has greater apoptosis inducing capacity, but most of the cancer cells become resistant to TRAIL-induced apoptosis. The combined treatment of TRAIL with natural products could restore the cancer cell sensitivity to recombinant human TRAIL (rhTRAIL) protein and might enhance the TNF-related apoptosis-inducing ligand receptor (TRAIL-R) expression. This investigation was aimed to isolate flavonoids from leaves of Avicennia marina and evaluate their potential for sensitization of rhTRAIL in human cervical cancer cells (SiHa). The methanolic extract of A.marina leaves were purified and structure was elucidated as isoquercitrin by NMR and LC-MS analysis. Isolated isoquercitrin showed cytotoxicity against SiHa cell line at IC50 of 980 μM. Messenger RNA (mRNA) expression of TRAIL-Rs was quantified by qRT-PCR, combination of isoquercitrin, and/or rhTRAIL increased TRAIL-R1 and TRAIL-R2 gene expression by 7 folds and 4 folds, respectively. Also, FACS assay revealed that combined treatment has increased the early apoptosis up to 7.24%. In the present study, we found that isoquercitrin enhances the mRNA expression of TRAIL-Rs, but the percentage of apoptosis was meager, possibly due to the influence of other anti-apoptotic proteins. 相似文献
37.
D. D. Sood 《Journal of Sol-Gel Science and Technology》2011,59(3):404-416
The paper reviews the sol–gel methods used for the preparation of nuclear fuel materials in the form of microspheres. It also
discusses how these microspheres can be fabricated into nuclear fuels for reactors such as High Temperature Gas Cooled Reactors
and Fast Reactors. The performance of these microsphere-based fuels is reviewed. More recent applications, such as the transmutation
of minor actinides, (Np, Am and Cm) and hydrogen production, are also briefly covered. 相似文献
38.
Kumar H Mukherjee B Lin ST Dasgupta C Sood AK Maiti PK 《The Journal of chemical physics》2011,134(12):124105
Experiments and computer simulations demonstrate that water spontaneously fills the hydrophobic cavity of a carbon nanotube. To gain a quantitative thermodynamic understanding of this phenomenon, we use the recently developed two phase thermodynamics method to compute translational and rotational entropies of confined water molecules inside single-walled carbon nanotubes and show that the increase in energy of a water molecule inside the nanotube is compensated by the gain in its rotational entropy. The confined water is in equilibrium with the bulk water and the Helmholtz free energy per water molecule of confined water is the same as that in the bulk within the accuracy of the simulation results. A comparison of translational and rotational spectra of water molecules confined in carbon nanotubes with that of bulk water shows significant shifts in the positions of the spectral peaks that are directly related to the tube radius. 相似文献
39.
We aim to understand the role of momentum-dependent interactions in transverse flow as well as in its disappearance. For the
present study, central collisions involving masses between 24 and 394 are considered. We find that the momentum-dependent
interactions have different impact in lighter colliding nuclei compared to heavier colliding nuclei. In lighter nuclei, the
contribution of the mean field towards flow is smaller compared to heavier nuclei where binary nucleon-nucleon collisions
dominate the scene. The inclusion of momentum-dependent interactions also explains the energy of the vanishing flow in the
12C + 12C reaction which otherwise was not possible with the static hard equation of state. An excellent agreement of our theoretical
attempt is found for balance energy with experimental data throughout the periodic table. 相似文献
40.
We study a multi-period oligopolistic market for a single perishable product with fixed inventory. Our goal is to address
the competitive aspect of the problem together with demand uncertainty using ideas from robust optimization and variational
inequalities. The demand function for each seller has some associated uncertainty and we assume that the sellers would like
to adopt a policy that is robust to adverse uncertain circumstances. We believe this is the first paper that uses robust optimization
for dynamic pricing under competition. In particular, starting with a given fixed inventory, each seller competes over a multi-period
time horizon in the market by setting prices and protection levels for each period at the beginning of the time horizon. Any
unsold inventory at the end of the horizon is worthless. The sellers do not have the option of periodically reviewing and
replenishing their inventory. We study non-cooperative Nash equilibrium policies for sellers under such a model. This kind
of a setup can be used to model pricing of air fares, hotel reservations, bandwidth in communication networks, etc. In this
paper we demonstrate our results through some numerical examples. 相似文献