全文获取类型
收费全文 | 1728篇 |
免费 | 60篇 |
国内免费 | 5篇 |
专业分类
化学 | 1163篇 |
晶体学 | 15篇 |
力学 | 40篇 |
数学 | 121篇 |
物理学 | 424篇 |
综合类 | 30篇 |
出版年
2023年 | 20篇 |
2022年 | 23篇 |
2021年 | 33篇 |
2020年 | 31篇 |
2019年 | 47篇 |
2018年 | 33篇 |
2017年 | 30篇 |
2016年 | 37篇 |
2015年 | 19篇 |
2014年 | 44篇 |
2013年 | 102篇 |
2012年 | 129篇 |
2011年 | 125篇 |
2010年 | 75篇 |
2009年 | 54篇 |
2008年 | 105篇 |
2007年 | 88篇 |
2006年 | 73篇 |
2005年 | 103篇 |
2004年 | 60篇 |
2003年 | 48篇 |
2002年 | 32篇 |
2001年 | 42篇 |
2000年 | 28篇 |
1999年 | 23篇 |
1998年 | 14篇 |
1997年 | 21篇 |
1996年 | 18篇 |
1995年 | 20篇 |
1994年 | 14篇 |
1993年 | 16篇 |
1992年 | 11篇 |
1991年 | 12篇 |
1989年 | 10篇 |
1988年 | 15篇 |
1986年 | 10篇 |
1985年 | 19篇 |
1984年 | 20篇 |
1983年 | 10篇 |
1982年 | 15篇 |
1981年 | 9篇 |
1980年 | 10篇 |
1979年 | 8篇 |
1978年 | 13篇 |
1976年 | 8篇 |
1975年 | 11篇 |
1974年 | 8篇 |
1972年 | 7篇 |
1971年 | 8篇 |
1970年 | 10篇 |
排序方式: 共有1793条查询结果,搜索用时 851 毫秒
121.
Novel anti-inflammatory peptides from the region of highest similarity between uteroglobin and lipocortin I 总被引:11,自引:0,他引:11
Significant future developments in the effective treatment of inflammatory diseases may arise from non-toxic dual inhibitors of both cyclooxygenase and lipoxygenase pathways in the arachidonate cascade. Inhibition of phospholipase A2(PLA2)(EC3.1.1.4), may provide such a dual action and recent research has concentrated on the role of PLA2-inhibitory proteins as possible anti-inflammatory agents. Blastokinin or uteroglobin is a steroid-induced rabbit secretory protein with PLA2-inhibitory activity. Its biochemical and biological properties have been extensively studied and its crystallographic structure has been resolved at 1.34 A (refs 15, 16). Lipocortins are a family of related proteins, which, it has been suggested, mediate the anti-inflammatory effects of glucocorticoids (for a review, see ref. 23). Some proteins of this group have been purified and the complementary DNA sequences of two human lipocortins are known. Lipocortins inhibit PLA2 in vitro, although their mechanism of action is still unclear. Recombinant lipocortin I inhibits eicosanoid synthesis in isolated perfused lungs from the guinea pig. Here, we report that synthetic oligopeptides corresponding to a region of high amino-acid sequence similarity between uteroglobin and lipocortin I have potent PLA2 inhibitory activity in vitro and striking anti-inflammatory effects in vivo. 相似文献
122.
S. Mukherjee 《Il Nuovo Cimento C》1996,19(2):237-243
Summary The neutrino emission from supernova 1987A is being studied by taking into consideration the effect of the magnetic field
present in the star. The magnetic field generates an anisotropic feature in the local space-time, which in turn leads to the
cancellation of the axial-vector part of the neutrino current. The interaction cross-section of these neutrinos in the course
of their interaction with matter on Earth has an inverse square energy dependence. The present work presents the calculations
based on this changed cross-section that relates to predictions of the expected number of events at KAMIOKANDE on the basis
of the Mont Blanc signal. It might be interesting to take a look into the implications of these results.
The author of this paper has agreed to not receive the proofs for correction. 相似文献
123.
The development of the theory of electron capture processes in ion-atom collisions is reviewed in the present work. The formal theory of scattering is used to obtain the Born and the distorted wave Born series for the rearrangement scattering matrix. On the basis of these series, the applications of the first and second Born approximation, the OBK approximation, the DWBA and the Padé approximants to electron capture processes are discussed. The impulse approximation, the Faddeev method and the second order potential method are also explained. The results of the investigations of the high energy behaviour of the charge transfer cross section based on the Faddeev-Watson multiple scattering expansion are analysed.The methods of molecular and atomic eigenfunction expansions are presented and their relative merits discussed. The semi-classical treatment for determining the differential electron capture probability is reviewed. Results obtained in works utilising expansions in Sturmian, Gaussian and pseudo-state wave functions are also presented. An integral equation approach to the close coupling approximation is described. The field theoretic approach to investigate the electron capture process is discussed in the last section.The results obtained by different theoretical methods are compared with available experimental results. 相似文献
124.
P. K. Mukherjee R. K. Moitra A. Mukherji 《International journal of quantum chemistry》1971,5(6):637-646
In this paper a fully coupled variation-perturbation theory has been introduced for handling open-shell atomic systems in the presence of static perturbations. The static dipolar and quadrupolar polarizabilities and shielding factors for Li, Be+, B2+, B, C+, Na and Al have been calculated and compared with available results. Important sources of discrepancies in previous calculations of shielding factors have been noticed and critically examined. The dipolar shielding factors calculated in this paper show satisfactory agreement with the theoretical N/Z ratio. In the absence of any theoretical test for the quadrupolar shielding factor, the accuracy of the calculations of γ∞, should be judged in the light of the accuracy of the corresponding β∞ values. 相似文献
125.
Mukherjee B Preece M Houston GC Papadakis NG Carpenter TA Hall LD Huang CL 《Magnetic resonance imaging》2005,23(9):907-920
Cerebral vascular reactivity in different regions of the rat brain was quantitatively characterized by spatial and temporal measurements of blood oxygenation level-dependent (BOLD)-fMRI signals following intravenous administration of the carbonic anhydrase inhibitor acetazolamide: this causes cerebral vasodilatation through a cerebral extracellular acidosis that spares neuronal metabolism and vascular smooth muscle function, thus separating vascular and cerebral metabolic events. An asymmetric spin echo-echo planar imaging (ASE-EPI) pulse sequence sensitised images selectively to oxygenation changes in the microvasculature; use of a surface coil receiver enhanced image signal-to-noise ratios (SNRs). Image SNRs and hardware integrity were verified by incorporating quality assurance procedures; cardiorespiratory stability in the physiological preparations were monitored and maintained through the duration of the experiments. These conditions made it possible to apply BOLD contrast fMRI to map regional changes in cerebral perfusion in response to acetazolamide administration. Thus, fMRI findings demonstrated cerebral responses to acetazolamide that directly paralleled the known physiological actions of acetazolamide and whose time courses were similar through all regions of interest, consistent with acetazolamide's initial distribution in brain plasma, where it affects cerebral haemodynamics by acting at cerebral capillary endothelial cells. However, marked variations in the magnitude of the responses suggested relative perfusion deficits in the hippocampus and white matter regions correlating well with their relatively low vascularity and the known vulnerability of the hippocampus to ischaemic damage. 相似文献
126.
In this paper we discuss the direct isotropic to chiral smectic-C phase transition on the basis of a phenomenological theory. The model free energy is written in terms of the coupled order parameters including the spontaneous polarization. We present a detailed analysis of the different phases that can occur and analyze the question under which conditions a direct isotropic to chiral smectic-C phase transition is possible when compared to other phase transitions. On the basis of this model the isotropic-smectic-C* transition is always of first order. The theoretical predictions are compared with the available experimental results.-1 相似文献
127.
C.?SurEmail author B. K.?Sahoo R. K.?Chaudhuri B. P.?Das D.?Mukherjee 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2005,32(1):25-31
We have employed the relativistic coupled cluster theory to calculate
the magnetic dipole and electric quadrupole hyperfine constants for
the ground and low lying excited states of singly ionized magnesium.
Comparison with experimental and the other theoretical results are
done and predictions are also made for a few low lying excited states
which could be of interest. We have made comparative studies of the
important many body effects contributing to the hyperfine constants
for the different states of the ion. 相似文献
128.
Valiente-Dobón JJ Steinhardt T Svensson CE Afanasjev AV Ragnarsson I Andreoiu C Austin RA Carpenter MP Dashdorj D de Angelis G Dönau F Eberth J Farnea E Freeman SJ Gadea A Garrett PE Görgen A Grinyer GF Hyland B Jenkins D Johnston-Theasby F Joshi P Jungclaus A Lieb KP Macchiavelli AO Moore EF Mukherjee G Napoli DR Phillips AA Plettner C Reviol W Sarantites D Schnare H Schumaker MA Schwengner R Seweryniak D Smith MB Stefanescu I Thelen O Wadsworth R 《Physical review letters》2005,95(23):232501
Three rotational bands in 74Kr were studied up to (in one case one transition short of) the maximum spin I(max) of their respective single-particle configurations. Their lifetimes have been determined using the Doppler-shift attenuation method. The deduced transition quadrupole moments reveal a modest decrease, but far from a complete loss of collectivity at the maximum spin I(max). This feature, together with the results of mean field calculations, indicates that the observed bands do not terminate at I = I(max). 相似文献
129.
We investigate the impact parameter-dependent parton distributions for a relativistic composite system in light-front framework. We express them in terms of overlaps of light-cone wave functions for a self-consistent two-body spin-
state, namely an electron dressed with a photon in QED. The pdf’s are distorted in the transverse space for transverse polarization of the state at one-loop level. 相似文献
130.