全文获取类型
收费全文 | 543篇 |
免费 | 18篇 |
出版年
2024年 | 3篇 |
2023年 | 5篇 |
2022年 | 24篇 |
2021年 | 35篇 |
2020年 | 15篇 |
2019年 | 27篇 |
2018年 | 24篇 |
2017年 | 19篇 |
2016年 | 20篇 |
2015年 | 20篇 |
2014年 | 16篇 |
2013年 | 31篇 |
2012年 | 39篇 |
2011年 | 33篇 |
2010年 | 20篇 |
2009年 | 18篇 |
2008年 | 22篇 |
2007年 | 20篇 |
2006年 | 16篇 |
2005年 | 11篇 |
2004年 | 6篇 |
2003年 | 6篇 |
2002年 | 7篇 |
2001年 | 14篇 |
2000年 | 6篇 |
1999年 | 5篇 |
1997年 | 10篇 |
1996年 | 6篇 |
1995年 | 5篇 |
1994年 | 5篇 |
1993年 | 4篇 |
1991年 | 2篇 |
1989年 | 5篇 |
1988年 | 2篇 |
1986年 | 5篇 |
1985年 | 3篇 |
1984年 | 3篇 |
1983年 | 3篇 |
1982年 | 2篇 |
1981年 | 3篇 |
1980年 | 3篇 |
1979年 | 3篇 |
1978年 | 2篇 |
1975年 | 3篇 |
1974年 | 4篇 |
1973年 | 3篇 |
1972年 | 2篇 |
1971年 | 4篇 |
1969年 | 3篇 |
1966年 | 4篇 |
排序方式: 共有561条查询结果,搜索用时 15 毫秒
1.
M. K. Soliman M. El. S. Easa M. Faisal I. M. Abou-Elazm F. M. Hetrick 《Antonie van Leeuwenhoek》1989,56(4):323-335
Infection of striped mullet (Mugil cephalus) with Aeromonas hydrophila results in an acute septicemic disease. The disease can be experimentally induced by intramuscular injection, skin or gill scarification or by the oral route using pellets purposely seeded with bacteria. The organism was isolated from the blood 1–2 days after infection and from all organs 24 hr or longer after infection. The disease is characterized by early inflammatory and proliferative changes and later necrotic changes. Enteritis and hepatic necrosis are constant findings in aeromonad disease of M. cephalus but surface lesions are not pathognomic for these infections in mullet. Death of infected fish may be attributed to bacterial toxins which cause necrosis of parenchymal organs and soft tissue structure. 相似文献
2.
The effect of NAD(P) and analogs of this nucleotide on nitrogenase activity in Rhodospirillum rubrum has been studied. Addition of NAD+ to nitrogen fixing Rsp. rubrum leads to inhibition of nitrogenase. NADP+ has the same effect but NADH or analogs modified in the nicotinamide portion do not cause inhibition. In contrast to ammonium
ions, addition of NAD+ leads to inhibition of nitrogenase in cells that have been N-starved under argon. The inhibitory effect of NAD+ is more pronounced at lower light intensities. Addition of NAD+ also leads to inhibition of glutamine synthetase, a phenomenon also occurring when “switchoff” is produced by the addition
of effectors such as ammonium ions or glutamine. It is also shown that NAD+ is taken up by Rsp. rubrum cells. 相似文献
3.
4.
Soliman A. Haroun 《Genetica》1996,98(1):103-106
Cytological studies were carried out on two wild species (L. hirsutum and L. pennellii) and the cultivated species (L. esculentum) of tomato and their F1 hybrids. Both parents and hybrids show a diploid chromosome number of 2n=24. The meiotic behaviour of the cultivated species showed a high degree of chromosome homology resulting in a high level of chiasmata frequency per bivalent. In contrast, the two wild species showed a slight increase in uniyalent frequency and a decrease in bivalent formation and chiasmata frequency. The meiotic behaviour of the hybrids showed a high level of univalents and low levels of bivalents as well as trivalents. Highly significant decreases in chiasmata frequency and increases in meiotic abnormalities, especially in the L. esculentum X L. pennellii hybrid, also were detected. The high meiotic irregularity and low chiasmata frequency recorded in the second hybrid indicated the disharmony and difference between its parental genomes and also served to predict its sterility. With regard to degree of pairing recorded in the hybrids, there is a possibility that sterility in such cases may refer to genetic factors in addition to the previously mentioned reasons. Pollen fertility showed no great difference between L. esculentum and L. hirsutum and their F1 hybrid, but a significant decrease was recorded in the L. esculentum X L. pennellii hybrid, which was clearly associated with high meiotic irregularity, low chiasmata frequency and chromosome association. 相似文献
5.
6.
Inhibition of the rat adrenal ornithine decarboxylase activity by immobilization stress and/or dexamethasone 总被引:2,自引:0,他引:2
Karam F.A. Soliman R.Renee Reams Matty O. Udoye Vani K. Nonavinakere 《Life sciences》1997,60(26):E1010-2387
The effects of immobilization stress and/or dexamethasone (DEX) on the adrenal ornithine decarboxylase (ODC) activities of sham-operated and adrenal-medulloectomized (enucleated) male Sprague-Dawley rats were investigated. On day 11 after surgery, rats were injected with saline or DEX (1 mg/kg), 3 h before the time of sacrifice (0600 h or 1800 h). Four groups, from sham-operated and enucleated rats (ENU) treated with saline or DEX were subjected to immobilization stress for 1 h prior to sacrifice. Groups of rats from stress-sham-DEX, non stress-sham-DEX, stress-sham, non stress-sham, stress-ENU-DEX, non stress-ENU-DEX, stress-ENU, and non stress-ENU were sacrificed at 0600 h or 1800 h on day 11 after surgery. Adrenal glands were excised and later analyzed for ODC activities. Results indicated that DEX and/or immobilization stress inhibited ODC activities (p < 0.05) in normal and regenerating adrenal glands at 1800 h and ODC activity varies diurnally, the activity being greater at 1800 h than at 0600 hours (p < 0.001). 相似文献
7.
Lynne H. Claye Hyacinth C. Akunne M. Duff Davis Steve DeMattos Karam F. A. Soliman 《Molecular neurobiology》1995,11(1-3):55-66
In order to determine whether repeated cocaine administration produced persistent changes in dopamine (DA) receptor binding and release consistent with behavioral sensitization, rats were treated with either cocaine (25 mg/kg ip) or saline twice daily for 14 consecutive days followed by a 3-d withdrawal period. The DA transporter site was assayed using [3H]GBR 12935, whereas D1 and D2 sites were assayed using [3H]SCH 23390 and [3H]spiperone, respectively. The density (B max) of the DA transporter binding sites in the ST of the cocaine-treated group increased significantly (p<0.05) over controls 3 d after the last injection, whereas the density of striatal D1 and D2 binding sites remained unchanged. The DA transporter in the nucleus accumbens (NA) was also studied with [3H]GBR 12935 and was unchanged following drug treatment. D1 and D2 binding parameters for the NA were not determined in this study. Furthermore, cocaine administration did not affect the affinities (K d ) of the radioligands used to label the transporter, D1, or D2 sites in any of the studies performed. In addition, striatal DA release was measured using in vivo microdialysis in anesthetized rats. Linear regression analysis on maximal decreases in DA release after apomorphine (0.02, 0.2, and 2.0 mg/kg sc) injection showed no difference in the functional capacity of the ST to modulate DA transmission between control and treated groups. Moreover, animals pretreated with cocaine showed a significant (p<0.01) decrease in locomotor activity (LA) after a presynaptic, autoregulating dose of apomorphine (0.03 mg/kg sc) was given. These results suggest that the effects seen after repeated exposure to cocaine may be regulated, in part, by changes in striatal DA transporter binding site densities and not necessarily by DA-releasing mechanisms or D1 and D2 receptor modification. 相似文献
8.
M. H. Soliman 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1980,56(4):175-182
Summary Seeds from 27 wild strains (18 tetraploids and 9 diploids) of Glycine weightii were germinated at a pH range of 5 to 8. The differences in germination (%) between all the strains were highly significant but between pH levels they were only nearly significant (P=0.067) with no interaction between pH levels and strains. Mean germination (%) for all tetraploids seems to be slightly higher ( 2%) than that for all diploids, especially at pH's 5, 7 and 8 but this may be due to the significantly longer time ( one day) it took tetraploids to complete germination. The apparent inverse relationship between seed weight and germination (%) was not significant.Mean germination time was highly significant for strains, pH's and their interaction. Increasing mean germination (%) resulted in decreasing mean germination time among strains. Large seeds took less time to germinate especially those from some of the tetraploid strains. This indicates that it is possible to produce a variety with high germination (%), fast germination rate and possibly large seeds. If the marked difference in pH tolerance among strains will prove to be mainly hereditary, then it will be also possible to select for either specific pH tolerance or tolerance at a wide range of pH. 相似文献
9.
Knopf P. M. and Soliman M. 1980. Effects of host endocrine gland removal on the permissive status of laboratory rodents to infection by Schistosoma mansoni. International Journal for Parasitology, 10: 197–204. The capacity of Schistosoma mansoni to complete its life cycle was compared in CD-1 mice (permissive hosts) and Sprague-Dawley rats (nonpermissive hosts) from which the pituitary gland had been removed prior to infection with cercariae. Except for a modest decrease in egg burden, none of the parameters of worm life cycle assessed were affected in hypophysectomized mice. In contrast, all these parameters were affected in hypophysectomized rats, e.g. onset of adult worm elimination was delayed, worm development improved, oviposition increased and miracidia developed. Effects of removal from rats of the thyroid/parathyroid glands on the parasite life cycle were similar to hypophysectomy; adrenalectomy or gonadectomy were without affect. Differences between thyroidectomized and thymectomized rats are discussed. It is concluded that host hormones contribute to the nonpermissive status of rats to Schistosoma mansoni infections. 相似文献
10.
We have analyzed, by means of density functional theory calculations and the embedded cluster model, the adsorption and spin-state
properties of Cr, Ni, Mo, and Pt deposited on a MgO crystal. We considered deposition at the Mg2+ site of a defect-free surface and at Li+ and Na+ sites of impurity-containing surfaces. To avoid artificial polarization effects, clusters of moderate sizes with no border
anions were embedded in simulated Coulomb fields that closely approximate the Madelung fields of the host surfaces. The interaction
between a transition metal atom and a surface results from a competition between Hund's rule for the adsorbed atom and the
formation of a chemical bond at the interface. We found that the adsorption energies of the metal atoms are significantly
enhanced by the cation impurities, and the adsorption energies of the low-spin states of spin-quenched complexes are always
more favorable than those of the high-spin states. Spin polarization effects tend to preserve the spin states of the adsorbed
atoms relative to those of the isolated atoms. The metal–support interactions stabilize the low-spin states of the adsorbed
metals with respect to the isolated metals, but the effect is not always enough to quench the spin. Spin quenching occurs
for Cr and Mo complexes at the Mg2+ site of the pure surface and at Li+ and Na+ sites of the impurity-containing surfaces. Variations of the spin-state properties of free metals and of the adsorption and
spin-state properties of metal complexes are correlated with the energies of the frontier orbitals. The electrostatic potential
energy curves provide further understanding of the nature of the examined properties. 相似文献