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   274篇
  免费   18篇
  国内免费   10篇
  2022年   5篇
  2021年   4篇
  2020年   5篇
  2019年   8篇
  2017年   2篇
  2016年   6篇
  2015年   3篇
  2014年   6篇
  2013年   10篇
  2012年   8篇
  2011年   14篇
  2010年   8篇
  2009年   11篇
  2008年   12篇
  2007年   8篇
  2006年   11篇
  2005年   8篇
  2004年   9篇
  2003年   7篇
  2002年   5篇
  2001年   3篇
  2000年   3篇
  1998年   4篇
  1997年   5篇
  1996年   6篇
  1995年   10篇
  1994年   11篇
  1993年   7篇
  1992年   12篇
  1991年   4篇
  1990年   12篇
  1989年   8篇
  1988年   8篇
  1987年   6篇
  1986年   4篇
  1985年   12篇
  1984年   10篇
  1983年   4篇
  1982年   4篇
  1981年   2篇
  1980年   3篇
  1979年   4篇
  1978年   1篇
  1976年   1篇
  1974年   1篇
  1973年   1篇
  1972年   1篇
  1971年   1篇
  1970年   1篇
  1969年   1篇
排序方式: 共有302条查询结果,搜索用时 15 毫秒
1.
Indirect double immunofluorescence labelling in the pharynx and lung of the bullfrog, Rana catesbeiana, demonstrated the occurrence, distribution, and coexistence of two neuropeptides. In the pharynx, immunoreactive calcitonin gene-related peptide (CGRP) and substance P (SP) were localized in nerve fibers distributed within and just beneath the ciliated epithelium. In the lung, CGRP and SP were localized in nerve fibers in five principal locations: 1) within the smooth muscle layer in the interfaveolar septa; 2) in the luminal thickened edges of the septa; 3) around the pulmonary vasculature; 4) within, and 5) under the ciliated epithelium. Within the smooth muscle layer in the septa, luminal thickened septa, and around blood vessels, almost all fibers showed coexistence of CGRP and SP. Within and just beneath the ciliated epithelium in the thickened septa, all fibers showed coexistence of CGRP and SP. No immunoreactivity for vasoactive intestinal polypeptide, neuropeptide Y, galanin, somatostatin, FMRFamide, and leucine-and methionine-enkephalins was detected in the nerve fibers within the larynx and the lung. Together with our previous data, the present findings suggest that peptidergic mechanisms are involved in the regulation of amphibian respiratory systems throughout their life.  相似文献   
2.
The presence and distribution of peptidergic nerve fibers were studied in the testis and mesorchium of the toad by means of immunohistochemistry. Cryostat sections of the testis and whole-mount preparations of mesorchia were immunostained with antisera to calcitonin gene-related peptide (CGRP) and neuropeptide tyrosine (NPY). After leaving the mesorchium CGRP-immunoreactive (IR) fibers were seen predominantly running in between the seminiferous tubules. In addition, a small population of CGRP-IR nerve fibers formed thin plexuses around blood vessels. Conversely, NPY-like immunoreactivity predominated in nerve fibers that formed dense plexuses around vessels both in the mesorchium and testis. Additionally, some single NPY-IR nerve fibers could be seen in both structures studied. The functional significance of these peptidergic systems in the testis of the toad remains to be analyzed.  相似文献   
3.
目的:检测复合应激大鼠模型阴茎组织中降钙素基因相关肽(CGRP)、血管活性肠肽(VIP)的表达,并观察伊木萨克片对二者表达的影响。方法:选用56只正常雄性SD大鼠,其中10只为正常对照组(N),余46只为造模组,采用富含环境雌激素饲料+寒冷环境的干预条件建立复合性应激大鼠模型(20 w),并随机将其分为模型组(B1)、自然恢复组(B2)和伊木萨克干预组(B3),药物干预2 w后,免疫组化及Western blot方法检测大鼠阴茎组织中CGRP、VIP的表达。结果:①大鼠阴茎组织中CGRP表达:B1、B2组较N组明显减少(P0.05);B3组较B1、B2组明显增多(P0.05)。②大鼠阴茎组织中VIP表达:B1、B2组较N组显著降低(P0.05);B3组较B1、B2组显著升高(P0.05)。结论:复合应激大鼠模型阴茎组织中CGRP、VIP明显减少,伊木萨克片干预可抑制此变化。  相似文献   
4.
目的:吴茱萸次碱(Rutaecarpa RUT)是芸香科植物吴茱萸的主要成分,它可激活辣椒素受体促进降钙素基因相关肽(CGRP) 等神经递质的释放来发挥药理作用。本实验的目的为观察吴茱萸次碱软膏对小鼠银屑病模型治疗作用。方法:通过药剂学方法制 成了不同浓度(2%, 5%, 10%)RUT 软膏,在小鼠尾部与背部银屑病模型给药14 天,观察小鼠尾部颗粒层形成的变化,给药结束后 取小鼠背部皮肤组织匀浆后采用放射免疫方法检测CGRP水平变化,并且取小鼠血浆检测CGRP水平变化。结果:不同浓度的吴 茱萸次碱软膏均能促进小鼠尾部颗粒层形成(P<0.05),并且浓度为5%与10%的RUT 软膏能显著降低小鼠背部CGRP 含量(P<0. 05),但是其对小鼠血浆的CGRP 没有影响。结论:吴茱萸次碱外用对小鼠银屑病模型有一定的治疗作用,这种作用与其促进小鼠 皮肤CGRP 释放而导致其含量降低有关。  相似文献   
5.
截至目前报道的中国块菌有28种,其中黑块菌4种,白块菌24种.具有重要经济价值和生态价值的黑块菌类有印度块菌复合种和中国夏块菌,其中印度块菌复合种与欧洲法国黑孢块菌属于姊妹类群,中国夏块菌与欧洲夏块菌也是姊妹类群.虽然欧洲意大利白块菌在中国尚未找到、波氏块菌在中国的存在尚待最终确认,但是,最近的更多白块菌新种的发现,说...  相似文献   
6.
邢明媚  韦知樱  许俊 《生物磁学》2011,(12):2398-2400
动脉粥样硬化是心血管疾病中最常见的一种血管病变,影响着血管、免疫、代谢等系统。动脉粥样硬化发生发展是一个复杂的过程,它损伤血管内皮,平滑肌等细胞,涉及到多种细胞因子的相互作用。而CGRP具有抑制血管平滑肌增值作用,对预防血管术后再狭窄有重要意义,CGRP能舒张血管,对防治氧化应激引起的内皮损伤具有保护作用,但其机制还不完全清楚。  相似文献   
7.
目的:分析丙泊酚在颅脑损伤手术中的效果及对血清C反应蛋白(CRP)、降钙素原(PCT)水平的影响。方法:选择2016年6月-2019年6月我院收治的颅脑损伤手术患者90例纳入本次研究,根据麻醉方式分为观察组(n=46)和对照组(n=44)。对照组使用依托咪酯进行麻醉诱导,观察组采用丙泊酚进行麻醉诱导。比较两组患者呼吸恢复时间、睁眼时间、拔管时间、不同时间血清CRP、PCT、心率(HR)、平均动脉压(MAP)、收缩压(SBP)及舒张压(DBP)、简易智能量表(MMSE)、视觉模拟(VAS)评分的变化情况及不良反应的发生情况。结果:观察组呼吸恢复时间、睁眼时间、拔管时间均显著短于对照组(P0.05)。术前,两组血清CRP、PCT水平比较无显著差异;术中,两组血清CRP、PCT水平均较术前明显下降,且观察组术中血清CRP、PCT水平均显著低于对照组(P0.05);术前,两组HR、MAP、SBP及DBP水平无显著差异;术中,两组HR、MAP、SBP及DBP水平均较术前显著升高,且观察组术中HR、MAP、SBP及DBP水平均显著低于对照组,术后两组HR、MAP、SBP及DBP水平均较术中明显下降,且观察组术后以上指标显著低于对照组(P0.05);术前,两组MMSE、VAS评分水平无明显差异;术后,两组MMSE、VAS评分水平均较术前明显下降,且观察组MMSE评分水平均显著高于对照组,VAS评分水平显著低于对照组(P0.05);两组不良反应总发生率分别为4.35%、11.36%,组间比较差异无统计学意义(P0.05)。结论:丙泊酚可降低颅脑损伤手术患者术中血清CRP、PCT水平,稳定血流动力学,并发挥术后镇痛作用。  相似文献   
8.
目的:探讨高频电磁场(high-frequency electromagnetic fields,HEMFs)曝露治疗急性胃损伤的作用机制。方法:选用健康SD大鼠,以Indomethacin灌胃法复制胃粘膜急性损伤模型,观察40.68MHz HEMFs(波长为7.3m)曝露(微热量,30—50mA,15min,1/d)治疗1或6次后,大鼠胃粘膜损伤程度(胃损伤指数和病理损伤积分)、胃粘膜血流量、血浆表皮生长因子(epidermal growth factor,EGF)和降钙素基因相关肽(calcitonin gene—related peptide,CGRP)水平。结果:HEMFs曝露1次后,胃粘膜血流量较对照组明显升高(P〈0.05),大鼠胃粘膜损伤程度、血浆EGF和CGRP水平较对照组均无显著性差异(P均〉0.05);HEMFs曝露6次后,胃粘膜损伤程度较对照组明显改善(P均〈0.05),胃粘膜血流量显著升高(P〈0.05),血浆EGF和CGRP水平较对照组无显著性差异(P均〉0.05)。结论:HEMFs曝露治疗大鼠胃粘膜急性损伤可能与其增加胃粘膜血流量有关,与血EGF和CGRP无关。  相似文献   
9.
Liu Z J  Liu K W  Chen L J  Lei S P  Li L Q  Shi X C  Huang L Q 《农业工程》2006,26(9):2791-2799
Paphiopedilum armeniacum is an endangered orchid species, endemic to China. During the period of April 2000 to October 2005, 66 observation sites were selected in Luoshapo of Nushan Mountains in Yunnan, China, to carry out the conservation ecological research on P. armeniacum. A total of 443 genets (1302 ramets in total) of P. armeniacum were sampled, their biological characteristics such as reproductive pattern, phenology, and life cycle were observed, and the ecological habits of the species such as the habitat and the structure of communities were studied. Experiments on ex-situ conservation were conducted, and the cloned ramets were replanted to their original habitat after ex-situ reproduction in Shenzhen, Guangdong, China. The relationships between P. armeniacum and climate, vegetation, other environmental factors in the original habitat, and the biological characteristics of asexual offsprings of P. armeniacum, which were replanted to the original habitat after ex-situ cultivation and reproduction, were investigated. The studies show that P. armeniacum in Luoshapo grows very well in secondary shrub boskets or in tussocks on limestone hills. It has both sexual and asexual reproduction. Asexual reproduction serves to complete the sexual reproduction and to extend the lifetime of genets, while it does not reduce sexual reproduction. There are two modes of asexual reproduction-by tillering or by producing rhizomes. The litter of shrub boskets or tussocks provides P. armeniacum with humus, and the rhizome reproduction of P. armeniacum is an adaptation to the litter-covered condition, i.e. to escape from the unfavorable environment. Blooming rate of ramets is 7.39% 1.02%, and fruit set rate from the blooming ramets is 32.23% 12.08%. P. armeniacum is able to invade the moderately destroyed forests and those in early restoring but is unable to grow in large dense forests. P. armeniacum also grows very well in artificial spare woods in Shenzhen and can reproduce many cloned ramets, which can normally bloom and yield fruits after being replanted to the original habitat. The results of this study show that P. armeniacum can be conserved by ex-situ conservation and by replanting the ex-situ reproduced ramets to original habitat. On the basis of the analysis of endangered mechanisms of P. armeniacum, it can be concluded that P. armeniacum has strong capability of both asexual and sexual reproductions, and an emergency mechanism consisted of massive production of rhizomes to cope with damage. Because highly effective pollinating insects that facilitate pollination in P. armeniacum are present in the habitat, flowering ramets produce fruits with large quantity of seeds, many of which in turn grow into new genets that can reproduce many cloned ramets. P. armeniacum makes very effective use of its environment and has distinct characteristics of enduring harsh environmental conditions; therefore, rather than its own inherent biological defects, the main threats facing this species are the destruction of its survival space and the wipe-out collecting of the plants as a result of trading. Based on the analysis mentioned above, certain appropriate strategies have been proposed for the conservation of P. armeniacum.  相似文献   
10.
陈磊  杨帅  杨磊  杨佳敏  沈小雨  孙洁  任晓暄  朱文莲  张露芬 《生物磁学》2013,(34):6634-6637,6736
目的:比较即刻电针天枢穴、足三里穴对肠易激综合征(ms)模型大鼠血浆降钙基因相关肽(CGRP)、内皮素(ET)水平及结肠组织中内皮素受体A(ETR-A)、CGRPmRNA表达的影响,旨在探讨电针即刻治疗IBS的部分机制。方法:采用WISTAR幼鼠制备肠易激综合征模型,随机分为空白对照组、模型组、天枢组、足三里组,每组8只。空白对照组不作任何处理,模型组只束缚不针刺,天枢组和足三里组在实验第8周电针治疗一次,留针20min。治疗结束后处死大鼠,取大鼠血浆及部分结肠组织进行生物活性物质检测。采用酶联免疫法检测血浆中CGRP、ET、结肠组织中ETR—A的含量,采用RT—PCR法检测结肠组织中CGRPmRNA表达。结果:(1)即刻电针对IBS模型大鼠血浆CGRP、ET水平的影响:与空白对照组比较,模型组CGRP水平明显降低(P〈0.01);与模型组比较,天枢组、足三里组CGRP水平明显升高(P〈0.01)。与空白对照组比较,模型组ET水平升高(P〈0.05);与模型组比较,天枢组ET水平明显降低(P〈0.01)。(2)即刻电针对IBS模型大鼠结肠组织ETR—A水平的影响:与空白对照组比较,模型组ETR—A水平明显升高(P〈0.01);与模型组比较,足三里组ETR-A水平明显降低(P〈0.01)。(3)即刻电针对IBS模型大鼠结肠组织CGRPmRNA表达的影响:与空白对照组比较,模型组、天枢组、足三里组CGRPmRNA表达明显增强(P〈0.01,P〈0.05);与模型组比较,足三里组CGRPmRNA表达减弱(P〈0.05)。结论:即刻电针介入后,能够调节机体的内环境紊乱和CGRP、ET的平衡失调。这种调节作用因穴位不同而具有不同的特点,天枢穴对血浆中CGRP、ET调节作用较强,足三里穴在受体和基因表达方面作用明显。  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