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   170篇
  免费   3篇
  173篇
  2024年   1篇
  2023年   1篇
  2022年   1篇
  2021年   6篇
  2020年   1篇
  2019年   3篇
  2018年   1篇
  2017年   1篇
  2016年   6篇
  2015年   9篇
  2014年   6篇
  2013年   11篇
  2012年   11篇
  2011年   9篇
  2010年   3篇
  2009年   6篇
  2008年   9篇
  2007年   7篇
  2006年   12篇
  2005年   4篇
  2004年   7篇
  2002年   4篇
  2000年   1篇
  1997年   2篇
  1996年   1篇
  1994年   1篇
  1993年   1篇
  1992年   3篇
  1991年   4篇
  1990年   1篇
  1989年   2篇
  1988年   1篇
  1984年   3篇
  1982年   2篇
  1980年   1篇
  1979年   3篇
  1978年   3篇
  1977年   1篇
  1975年   1篇
  1974年   3篇
  1973年   1篇
  1972年   5篇
  1971年   1篇
  1970年   4篇
  1969年   2篇
  1968年   4篇
  1967年   1篇
  1966年   2篇
排序方式: 共有173条查询结果,搜索用时 15 毫秒
51.
Nicotine consumed upon smoking affects numerous physiological processes through nicotinic acetylcholine receptors, which mediate cholinergic regulation by the neuronal and endogenous acetylcholine. Consequently, nicotinic receptors are expressed in many non-excitable tissues including the blood. In spite of the documented effect of nicotine on hematopoiesis, little is known about the expression and role of nicotinic receptors in the course of blood cell differentiation. The aim of the present study was to investigate whether and how nicotinic receptors are involved in the development of myeloid and erythroid cells within the bone marrow. The presence of nicotinic receptors containing alpha4(beta2) and alpha7 subunits in the bone marrow cells of C57Bl/6 mice was shown by the binding of [125I]-alpha-bungarotoxin or [3H]-Epibatidine and by flow cytometry with subunit-specific antibodies or fluorescein-labeled alpha-cobratoxin. Both TER119+ (erythroid) and CD16+CD43med (myeloid) progenitor cells bound more alpha4-specific antibodies than their mature forms, while the binding of alpha-cobratoxin and alpha7-specific antibodies was also high in mature cells. According to morphological analysis, either the absence of alpha7-containing nicotinic receptors in knockout mice or their desensitization in mice chronically treated with nicotine decreased the number of myeloid and erythroid progenitors and junior cells. In contrast, the absence of beta2-containing receptors favored myelocyte generation and erythroid cell maturation. It is concluded that the development of both myeloid and erythroid cell lineages is regulated by endogenous cholinergic ligands and can be affected by nicotine through alpha7- and alpha4beta2-containing nicotinic receptors, which play different roles in the course of the cell maturation.  相似文献   
52.
We conducted an association study of ten polymorphisms in six candidate genes of OA (rs1799750 (MMP1), rs35068180 (MMP3), rs2252070 (MMP13), rs63118460 and rs2276455 (COL2A1), rs143383 (GDF5), rs1544410, rs7975232, rs731236, and rs2228570 (VDR)) with the development of osteoarthritis (OA) in 333 women taking into account the localization of the pathological process, the age of disease manifestation, and ethnicity and investigated the presence of signs of undifferentiated connective tissue dysplasia (UCTD). On the basis of clinical and genetic data, we revealed statistically significant models to predict the development of osteoarthritis of various localizations (knee, hip, and generalized forms).  相似文献   
53.
A recombinant form of human soluble CD23 (sCD23), the low affinity receptor for IgE (FcepsilonRII), was produced by PCR cloning the lectin-binding domain sequence into a bacterial expression vector. After renaturation and purification, the sCD23 bound IgE and divalent metal ions, indicating its activity. The recombinant human sCD23 exhibited similar proinflammatory properties as the native protein. Although interleukin-1beta, tumour necrosis factor-alpha, and nuclear factor-kappaB appeared not to be enhanced significantly in unstimulated RPMI 8866 B-lymphoblastoid and U937 promonocytic cell lines with 24 h incubation of recombinant sCD23, they were produced in both healthy and hyper-IgE-derived peripheral blood mononuclear cells, especially tumour necrosis factor-alpha. This study concludes that while recombinant and chimeric sCD23 may be useful in blocking IgE binding to immune cells and decreasing IgE synthesis by B-lymphocytes, the production of proinflammatory cytokines, particularly tumour necrosis factor-alpha will enhance immune responses in cases of asthma, allergy, and hyper-IgE syndrome.  相似文献   
54.
It was shown that the dose--effect curves describing the radiosensitivity of CFUc of the bone marrow irradiated in vitro (0.04-3.7 Gy) and treated with normal rabbit serum (NRS) and anti-mouse-brain serum (AMBS) has two differently sloping portions indicating that two CFUc populations differing in radiosensitivity are present in the bone marrow. D0 was 0.93 Gy after irradiation with doses of 0.04-0.75 Gy and treatment with NRS, and 0.33 Gy after incubation of the bone marrow with AMBS. The addition of thymus cells "straightened" the dose--effect curve for the bone marrow treated with AMBS: in this case D0 was 1.81 Gy exceeding considerably the values of D0 for intact bone marrow. The CFUc population is suggested to be heterogeneous in radiosensitivity.  相似文献   
55.
In 50 human embryos at the age of 21 days--12 weeks of development, including the stages X-XXIII and beginning of the fetal period according to Carnegie's classification, spatial-temporal regularities on rearrangement of cellular material in the mesenchymal derivatives of the ocular auxiliary apparatus have been investigated. The main attention has been paid to ascertain the moments, when the first signs of differences appear in the previously homogenous cellular material of the differentiating mesenchyme around the ocular cup and in the eyelids, taking into account appearance of derivates in the ocular auxiliary apparatus: sclera, oculomotor muscles, stroma of the lacrimal gland, cartilagenous laminae in the eyelids and in the orbicular muscle. Regularities of cytochemical differentiation of the mesenchyme and its derivatives have been studied, taking into account the organ's changing topography. Morphometrical investigations of cells in the anlages mentioned are expanded and correlated with the time of their cytochemical differentiation. Correlation of the morphometrical and cytochemical data with the histological investigations has been performed.  相似文献   
56.
Antibacterial activity of 7 aminoglycoside antibiotics and combinations of tobramycin or gentamicin with carbenicillin was studied with respect to 33 clinical strains of Ps. aeruginosa. Tobramycin, sisomicin, gentamicin and amicacin showed high levels of antibacterial activity. Tobramycin and sisomicin were 3-4 and 2 times more effective than gentamicin. 100 per cent of the Ps. aeruginosa isolates was sensitive to tobramycin and amicacin. The number of the isolates sensitive to sisomicin and gentamicin amounted to 97 and 94 per cent respectively. The respective numbers for streptomycin and kanamycin were 32 and 11 per cent. No monomycin sensitive isolates were detected. Combination of tobramycin or gentamicin with carbenicillin increased the antibacterial activity of the aminoglycoside antibiotics by 2-16 times and that of carbenicillin by 2-32 times. The synergistic effect of gentamicin or tobramycin with carbenicilin was observed with respect to 50 and 58 per cent of the isolates respectively. No antagonistic effect was detected on the combined use of the antibiotics. The majority of the isolates (96 per cent) were sensitive to combinations of carbenicillin in a concentration of 50 micrograms/ml with tobramycin or gentamicin in concentrations of 0.15 or 0.3 micrograms/ml respectively.  相似文献   
57.
The influence of preliminary subthreshold activation of thalamic intralaminary nuclei on achievement of instrumental reflex and on inhibitory effects, caused by stimulation of the caudate nucleus head, were studied in chronic experiments on 5 dogs with a model of instrumental defensive conditioned reflexes, providing for maintainance of a given posture. It was shown that the preceding high-frequency electrostimulation of intralaminary nuclei activates motor components of the instrumental response (shortened latency, EMG and mechanogram of the response, increased amplitude of instrumental response) and significantly lowers threshold strength of the current, necessary for obtaining "caudate pause". The greatest increase in inhibitory influences, caused by stimulation of the caudate nucleus head, was observed when thalamic stimulation preceded stimulations, localized in the dorsolateral segment of the caudate nucleus head. The obtained data are discussed in aspect of Buchwald et al. hypothesis on the existence of "caudate loop".  相似文献   
58.
It has been shown that the effect of stimulation of the caudate nucleus head in the contralateral hemisphere differs at different stages of achievement of a defensive instrumental habit in dogs. Stimulation preceding the action of the conditioned signal or delivered simultaneously with the beginning of the latter did not change the criteria for the achievement of successive programs of the instrumental defensive reaction. Stimulation of the same areas in the last phase of the instrumental response, as a rule, lead to the cessation of instrumental movement. A conclusion has been drawn that in a defensive situation the inhibitory influence of the caudate nucleus on instrumental behaviour of intact dogs is not so sharply expressed as in experiments with alimentary reinforcement. In dogs with a preliminary ablation of the CI and CII cortical zones of the contralateral hemisphere, stimulation of the caudate nucleus head was attended with a sharp drop in every criterion of the instrumental defensive reactions.  相似文献   
59.
60.
Carminomycin was shown to inhibit the development of both the DNA-containing variolovaccine virus and the RNA-containing grippe virus in chick embryos. Comparison of the effects of rubomycin, carminomycin, 14-oxy-carminomycin and carminomycin complex with bovine serum albumin in experiments with chick embryos showed that the inhibitory effect of carminomycin and its derivatives on the development of the grippe virus was much higher than that of rubomycin. The carminomycin derivatives proved to be much more active in this respect than the initial antibiotic. Carminomycin and its derivatives had a therapeutic effect on mice with experimental grippe pneumonia also on their oral use.  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