首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   192篇
  免费   4篇
  2022年   2篇
  2021年   3篇
  2018年   1篇
  2017年   2篇
  2016年   2篇
  2015年   5篇
  2014年   7篇
  2013年   6篇
  2012年   7篇
  2011年   17篇
  2010年   6篇
  2009年   13篇
  2008年   11篇
  2007年   15篇
  2006年   13篇
  2005年   6篇
  2004年   4篇
  2003年   3篇
  2002年   5篇
  2001年   2篇
  2000年   2篇
  1998年   1篇
  1997年   1篇
  1996年   3篇
  1995年   1篇
  1994年   2篇
  1993年   1篇
  1991年   6篇
  1989年   2篇
  1988年   1篇
  1985年   1篇
  1984年   2篇
  1983年   1篇
  1981年   6篇
  1980年   5篇
  1979年   3篇
  1978年   1篇
  1977年   1篇
  1976年   1篇
  1975年   1篇
  1974年   2篇
  1972年   1篇
  1971年   1篇
  1970年   3篇
  1969年   1篇
  1968年   2篇
  1966年   2篇
  1958年   2篇
  1957年   5篇
  1956年   3篇
排序方式: 共有196条查询结果,搜索用时 109 毫秒
121.

Background and Aims

Anti-sperm antibodies in can markedly reduce the likelihood of natural conception. The etiology of this anti-sperm immunity in human females is unknown. We compared the cytokine response of peripheral blood mononuclear cells (PBMCs) from infertile patients with or without anti-sperm antibodies (ASA) and fertile women.

Methodology/Principal Findings

We cultivated the PBMCs together with sperm antigens (whole cells or cell lysate), and screened the supernatants for 40 cytokines by antibody array. When stimulated with whole sperm cells, the PBMCs from patients with ASA produce less IL-3, IL-11, IL-13, ICAM-1, GCSF and more IL-2, IL-4 and IL-12p70 as compared to healthy women. PBMCs from patients with ASA produce typically less IL-13, IL-7, IL-17 and MIG, and more MIP-1β and IL-8, as compared to PBMCs from patients without ASA. In response to sperm cell lysate, PBMCs from infertile women without ASA respond initially by increase in production of growth factors (GCSF, GM-CSF and PDGF-BB) followed by increase in chemokines (e.g. IL-8, MCP-1 and MIP-1β).

Conclusions

Cellular immune responses to sperm antigens, measured by production of cytokines, differ among infertile women with ASA, infertile women without ASA and healthy women. This difference could play an important role in the initial steps of the infertility pathogenesis.  相似文献   
122.
N-methyl-d-aspartate (NMDA) receptors are glutamate ionotropic receptors that play critical roles in synaptic transmission, plasticity, and excitotoxicity. The functional NMDA receptors, heterotetramers composed mainly of two NR1 and two NR2 subunits, likely pass endoplasmic reticulum quality control before they are released from the endoplasmic reticulum and trafficked to the cell surface. However, the mechanism underlying this process is not clear. Using truncated and mutated NMDA receptor subunits expressed in heterologous cells, we found that the M3 domains of both NR1 and NR2 subunits contain key amino acid residues that contribute to the regulation of the number of surface functional NMDA receptors. These key residues are critical neither for the interaction between the NR1 and NR2 subunits nor for the formation of the functional receptors, but rather they regulate the early trafficking of the receptors. We also found that the identified key amino acid residues within both NR1 and NR2 M3 domains contribute to the regulation of the surface expression of unassembled NR1 and NR2 subunits. Thus, our data identify the unique role of the membrane domains in the regulation of the number of surface NMDA receptors.  相似文献   
123.
Methanogenesis-driven ATP synthesis in a neomycin-resistant mutant of Methanothermobacter thermautotrophicus (formerly Methanobacterium thermoautotrophicum strain DeltaH) was strongly inhibited at both pH 6.8 and pH 8.5 by the uncoupler 3,3',4',5 -tetrachlorosalicylanilide (TCS) in the presence of either 1 or 10 mM NaCl. The generation of a membrane potential in the mutant cells at pH 6.8 was also strongly inhibited by TCS in the presence of 1 or 10 mM NaCl. On the other hand, at pH 8.5 in the presence of 10mM NaCl, a protonophore-resistant membrane potential of approximately 150 mV was found. These results indicate that in the mutant cells the process of energy transduction between methanogenesis and membrane potential generation is not impaired. In contrast to the wild-type strain, ATP synthesis in the mutant cells was driven by an electrochemical gradient of H(+) under alkaline conditions. Unlike wild-type cells, the mutant lacks the capacity to transduce an uncoupler-resistant membrane potential energy at pH 8.5 into ATP synthesis. Na(+)/H(+) exchange was comparable in the wild type and the mutant cells. Western blots of sub-cellular fractions with polyclonal antiserum reactive to the B-subunit of the halobacterial A-type H(+)-translocating ATPase confirmed the presence of A-type ATP synthase in the mutant cells. Furthermore, in the mutant cells a protein band of molecular mass about 45 kDa is absent but there was an abundant protein band at about 67 kDa. Based on the observed bioenergetic features of the mutant cells, neither the A(1)A(o) ATP synthase alone nor together with the Na(+)/H(+) antiporter seems to be responsible for ATP synthesis driven by sodium motive force. Rather, some other links between neomycin-resistance and failure of sodium motive force-dependent ATP synthesis in the neomycin resistant mutant are discussed.  相似文献   
124.
The parallel course of the excretion rates of sodium and bromide ions was demonstrated in adult male rats administered simultaneously with 24Na-sodium chloride and 82Br-bromide. These excretion rates were inversely proportional to the magnitude of sodium intake in the animals. The biological half-life of bromide, as a substitute for sodium or chloride, was investigated with the aid of the radionuclide 82Br in animals situated in very different physiological states (i.e., in lactating and nonlactating female rats as well as in young rats of varying ages [2,4,6, and 10 wk of age]). The 82Br radioactivity retained in mothers and in whole litters was measured in vivo at appropriate time intervals (up to 240 h) after the application of 82Br-bromide to the mothers. The time-course of the changes in the 82Br radioactivity of the young was calculated as the difference between the rate of 82Br intake in the mother's milk and the 82Br excretion through the kidneys into the urine. The rate of 82Br excretion through the kidneys of the dam could be calculated also. Nonweaned young rats (12 d) had the highest half-life (269 h) and lactating dams had the lowest (44 h). The determined values demonstrated that nonweaned young apparently conserve sodium, because of its relatively low concentration in mother's milk, whereas lactating dams, because of their large food intake, waste sodium. Presented in part at the 4th International Symposium on Trace Elements in Human: New Perspectives held in Athens (Greece) on 9–11 October 2003  相似文献   
125.
126.
A shake-and-wash technique for monitoring the predatory phytoseiid mitesTyphlodromus pyri, Amblyseius finlandicus, and their prey,Panonychus ulmi, Tetranychus urticae andAculus schlechtendali in commercial apple orchards was developed. The removal and recovery of mites from leaves, shoots and spurs is based on agitating the plant material by hand in alcohol and subsequently removing the mites using a separating funnel. The mites are quickly killed and easily washed off the plant material, and are thus well preserved for further study. The technique is more efficient than directly counting the mites on plant material under a dissection microscope and can be easily employed both in the laboratory and in the field.  相似文献   
127.
Communities of phytophagous and predatory mites on vine can be influenced by the type of chemical treatment. Ten species of phytoseiid mites inhabit vines in the region of South Moravia. Populations ofTyphlodromus pyri Scheuten play leading roles in effective suppression of tetranychid and eriophyid mites in commercial vineyards sprayed with pesticides, except synthetic pyrethroids and mancozed, which are considered to be detrimental to the predatory phytoseiid mites.  相似文献   
128.
Fluctuations in the body fluids of long-ranged humoral substance(s) capable of stimulating the growth of bone marrow granulocytic and macrophage-like cells in diffusion chamber cultures in vivo, was observed after whole body irradiation of mice. The fluctuation pattern was similar to that of the in vitro colony stimulating factor(s) of the sera of irradiated mice which indicates a relation between in vivo and in vitro active factor(s).  相似文献   
129.
A survey is given of three natural groups of the subsectionHeterophylla (Witas.)Fed. of the genusCampanula L. Within theSaxicolae four taxa of higher rank have been revealed:c. xylocarpa Kovanda (2n=34),C. gentilis Kovanda (2n=34),C. moravica (Spitzner)Kovanda subsp.moravica (2n=68), andC. moravica subsp.xylorrhiza (O. Schwarz)Kovanda (2n=102). BothAlpicolae andLanceolatae are represented by a single species: the first byC. cochleariifolia Lam. (2n=34), the latter byC. serrata (Kit. ap.Schult.)Hendrych (2n=34). Cytology, ecology and geographical distribution of all these taxa have been reviewed, and relationships to the other members of the complex discussed. Infraspecific variation within each species has also been examined.  相似文献   
130.
In this paper, a newCampanula species is described from Eastern Slovakia. Its morphological, distributional and cytological relationships and ecological preferences are briefly discussed and affinity to the otherSaxicolae examined. The taxon is characterized by the following features: specific combination of constant morphological characters; diploid chromosome number (2n=34); ecological specialization to the fissures of limestone and dolomitic rocks; relict occurrence in a small, sharply limited area; very late flowering. Geographically, it appears to be the northernmost representative of theSaxicolae.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号