全文获取类型
收费全文 | 548篇 |
免费 | 8篇 |
出版年
2022年 | 6篇 |
2021年 | 6篇 |
2020年 | 8篇 |
2019年 | 5篇 |
2018年 | 4篇 |
2017年 | 16篇 |
2016年 | 15篇 |
2015年 | 8篇 |
2014年 | 11篇 |
2013年 | 22篇 |
2012年 | 23篇 |
2011年 | 17篇 |
2010年 | 18篇 |
2009年 | 7篇 |
2008年 | 24篇 |
2007年 | 23篇 |
2006年 | 19篇 |
2005年 | 24篇 |
2004年 | 14篇 |
2003年 | 10篇 |
2002年 | 19篇 |
2001年 | 14篇 |
2000年 | 19篇 |
1999年 | 10篇 |
1998年 | 4篇 |
1992年 | 5篇 |
1990年 | 5篇 |
1989年 | 12篇 |
1988年 | 12篇 |
1987年 | 13篇 |
1986年 | 5篇 |
1985年 | 9篇 |
1984年 | 8篇 |
1983年 | 7篇 |
1981年 | 3篇 |
1980年 | 2篇 |
1979年 | 15篇 |
1978年 | 4篇 |
1976年 | 6篇 |
1975年 | 11篇 |
1974年 | 18篇 |
1973年 | 9篇 |
1972年 | 5篇 |
1971年 | 13篇 |
1970年 | 7篇 |
1969年 | 6篇 |
1968年 | 8篇 |
1967年 | 9篇 |
1966年 | 9篇 |
1965年 | 3篇 |
排序方式: 共有556条查询结果,搜索用时 15 毫秒
91.
The effects of mutations and genetic background on the mating activity of males and receptivity of females Drosophila melanogaster have been studied at different population densities. Population density, as well as its combinations with other factors, significantly affects mating behavior of D. melanogaster. There are two distinct trends in the effect of this factor on mating behavior: the maximum larval overpopulation may cause either a significant suppression of the behaviors studied or an increase in their expressivity. The mating behaviors of w a and cn mutants against a certain genetic background changed similarly in response to varying population density. 相似文献
92.
Using a patch-clamp technique in the whole-cell configuration, we studied the effect of an exogenous antioxidant, dithiothreitol
(DTT), on transmembrane currents in isolated cells obtained from the rat spinal ganglia. We demonstrated that this antioxidant
(DTT) is capable of modulating the proton-gated current. In most neurons, proton-gated currents increased in the presence
of the antioxidant. Since proton-gated receptor-channel complexes of sensory neurons are involved in different processes of
signalling and transmission of sensory information in the peripheral nervous system, we hypothesize that the influences mediated
by alterations of the concentrations of antioxidants participate in the formation of the state of algesia under normal physiological
conditions and of that of hyperalgesia in pathological states. In addition, oxidative stress, which causes a shift in the
balance of concentrations of antioxidants, accompanies numerous abnormal pathophysiological states, in particular diabetes,
ischemia, and inflammation. Since proton-gated channels are permeable for calcium ions, an antioxidant-induced increase in
calcium signalling can be significantly important for a number of biochemical processes occurring in tissues.
Neirofiziologiya/Neurophysiology, Vol. 38, No. 3, pp. 193–197, May–June, 2006. 相似文献
93.
Importance of disturbance history on net primary productivity in the world's most productive forests and implications for the global carbon cycle
下载免费PDF全文
![点击此处可从《Global Change Biology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Liubov Volkova Stephen H. Roxburgh Christopher J. Weston Richard G. Benyon Andrew L. Sullivan Philip J. Polglase 《Global Change Biology》2018,24(9):4293-4303
Analysis of growth and biomass turnover in natural forests of Eucalyptus regnans, the world's tallest angiosperm, reveals it is also the world's most productive forest type, with fire disturbance an important mediator of net primary productivity (NPP). A comprehensive empirical database was used to calculate the averaged temporal pattern of NPP from regeneration to 250 years age. NPP peaks at 23.1 ± 3.8 (95% interquantile range) Mg C ha?1 year?1 at age 14 years, and declines gradually to about 9.2 ± 0.8 Mg C ha?1 year?1 at 130 years, with an average NPP over 250 years of 11.4 ± 1.1 Mg C ha?1 year?1, a value similar to the most productive temperate and tropical forests around the world. We then applied the age‐class distribution of E. regnans resulting from relatively recent historical fires to estimate current NPP for the forest estate. Values of NPP were 40% higher (13 Mg C ha?1 year?1) than if forests were assumed to be at maturity (9.2 Mg C ha?1 year?1). The empirically derived NPP time series for the E. regnans estate was then compared against predictions from 21 global circulation models, showing that none of them had the capacity to simulate a post‐disturbance peak in NPP, as found in E. regnans. The potential importance of disturbance impacts on NPP was further tested by applying a similar approach to the temperate forests of conterminous United States and of China. Allowing for the effects of disturbance, NPP summed across both regions was on average 11% (or 194 Tg C/year) greater than if all forests were assumed to be in a mature state. The results illustrate the importance of accounting for past disturbance history and growth stage when estimating forest primary productivity, with implications for carbon balance modelling at local to global scales. 相似文献
94.
L. A. Volkova V. V. Urmantseva A. B. Burgutin A. M. Nosov 《Russian Journal of Plant Physiology》2018,65(3):427-434
To unravel mechanisms of elicitor action of furostanol glycosides (FGs), the formation of superoxide anion after the addition of FGs to a suspension culture of yam (Dioscorea deltoidea Wall. ex Griseb) cells was studied. The substantial increase in superoxide level, evaluated by nitroblue tetrazolium (NBT) reduction to formazan, was found at the exponential phase of cell growth. The involvement of NADPH oxidase in the superoxide generation was revealed by means of inhibitory analysis. Diphenyliodonium chloride (DPI), the inhibitor of NADPH oxidase, compromised the action of FGs. Meanwhile, the elimination of apoplastic peroxidase did not affect the accumulation of formazan, which suggests the involvement of NADPH oxidase but not peroxidase in the superoxide generation. In addition to NBT-test, the superoxide formation was judged by changes in activity of superoxide dismutase (SOD). Exogenous FGs activated the enzyme due to the increased production of superoxide anion. In this case, DPI decreased SOD activity that conforms to the NADPH oxidase involvement in the superoxide generation. The analysis of antioxidant activity of FGs by inhibition of radicals of 2,2-diphenyl-1-picrylhydrazyl showed that FGs are weak reductants in comparison with ascorbic acid. The results of the work allow for the suggestion that, supposing a weak reducing capacity of FGs, the special feature of their exogenous action on cultured yam cells is the increase in the level of superoxide anion radical mainly produced by NADPH oxidase. 相似文献
95.
Chromosomal rearrangements with a common breakpoint at 6p23 in five cases of myeloid leukemia 总被引:1,自引:0,他引:1
E. W. Fleischman E. L. Prigogina G. W. Iljinskaja L. N. Konstantinova G. P. Puchkova M. A. Volkova M. A. Frenkel S. A. Balakirev 《Human genetics》1983,64(3):254-256
Rearrangement of the short arm of chromosome 6 with a breakpoint at 6p23 was found in five patients with myeloid leukemia. Three of them had different morphological variants of AML (M2, M3, M4) and two blastic crisis of Ph1 negative and Ph1 positive CML. Identical translocation, t(6;9)(p23;q34), was revealed in two patients. One of them had AML (M2), the other blastic crisis of Ph1 negative CML. The blast cells of the last patient were morphologically similar to those in the M2 variant of AML. Translocation (6;9)(p23;q34) was also detected in two AML patients of Rowley and Potter (1976). The role of the breakpoint at 6p23 in myeloid malignancies needs further investigation. 相似文献
96.
L I Barsukov Y E Shapiro A V Viktorov V I Volkova V F Bystrov L D Bergelson 《Biochemical and biophysical research communications》1974,60(1):196-203
NMR spectroscopy with the use of non-penetrating paramagnetic probes permits in situ determination of the composition of the outer surface of phospholipid vesicles. The method was employed to follow the phospholipid exchange between phosphatidylinositol and phosphatidylcholine vesicles induced by a postmicrosomal protein fraction from rat liver. The effects of these proteins on the lipid bilayer and the structure of the vesicles produced by exchange were studied. 相似文献
97.
Chromosomes in acute nonlymphocytic leukemia 总被引:1,自引:1,他引:0
E. L. Prigogina E. W. Fleischman G. P. Puchkova S. A. Mayakova M. A. Volkova A. K. Protasova M. A. Frenkel 《Human genetics》1986,73(2):137-146
Summary The karyotype of leukemic cells was studied in 88 acute nonlymphocytic leukemia (ANLL) patients. Chromosome abnormalities were discovered in 78.4% of all patients and in 72.5% of the 69 patients studied before treatment. Characteristic abnormalities: translocations 8;21, 15;17, 9;22 or 6;9, rearrangements of 11q, gain of chromosomes 8 or 21, and loss or deletion of chromosomes 5 or 7 were detected in 56 of 69 patients with abnormal karyotypes. Translocation 8;21 was revealed in 27 patients; 20 of them had M2 FAB-form, four had M1, and three had M4. In patients with t(8;21) the incidence of complete remission was higher and the duration of first remission and survival longer than in patients with other abnormalities or with a normal karyotype. 相似文献
98.
The N-terminal amino acid sequence of a neurotoxin from the venom of Latrodectus mactans tredecimguttatus (alpha-latrotoxin) was determined. Latrotoxin was subjected to the tryptic cleavage and total or partial amino acid sequences of 25 peptides were established. In total the tryptic fragments contained 252 amino acid residues. Essential structural information on cloning of the latrotoxin structural gene was obtained. 相似文献
99.
N A Markova V A Agranenko N N Tibilova R I Volkova 《Folia haematologica (Leipzig, Germany : 1928)》1987,114(4):512-516
An alkaline resuspension solution "Erythronaph" with adenine and nicotinamide has been developed. It allows to preserve red blood cells for 35 days. Removing leukocytes and platelets up to 90% by brief warning of 24-hour blood prior to centrifugation combined with return of 10% of plasma provide further prolongation of storage of red blood cells in "Erythronaph". 相似文献
100.
The effects of bis(adenosyl-5)oligophosphates on cation conductance-promoting ATP receptors at the somatic membrane of rat sensory ganglia neurons were investigated. Both bis(adenosyl-5)tetraphosphate and bis(adenosyl-5)pentaphosphate act as partial agonists of ATP receptors at saturating concentration and activate ionic currents of almost one order of magnitude below the amplitude of peak ATP-activated currents. Combined application of these two substances to the neuron produces a considerable decline in the amplitude of ATP-activated ionic currents, competing with ATP for common binding sites.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 20, No. 4, pp. 427–431, July–August, 1988. 相似文献