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   1849篇
  免费   92篇
  国内免费   33篇
耳鼻咽喉   23篇
儿科学   49篇
妇产科学   15篇
基础医学   97篇
口腔科学   57篇
临床医学   299篇
内科学   181篇
皮肤病学   29篇
神经病学   83篇
特种医学   69篇
外科学   167篇
综合类   296篇
预防医学   183篇
眼科学   18篇
药学   308篇
中国医学   29篇
肿瘤学   71篇
  2021年   6篇
  2020年   5篇
  2019年   7篇
  2018年   3篇
  2017年   18篇
  2016年   6篇
  2015年   163篇
  2014年   197篇
  2013年   143篇
  2012年   119篇
  2011年   215篇
  2010年   84篇
  2009年   140篇
  2008年   78篇
  2007年   162篇
  2006年   104篇
  2005年   45篇
  2004年   41篇
  2003年   28篇
  2002年   19篇
  2001年   25篇
  2000年   14篇
  1999年   19篇
  1998年   17篇
  1997年   27篇
  1996年   27篇
  1995年   22篇
  1994年   22篇
  1993年   22篇
  1992年   16篇
  1991年   19篇
  1990年   15篇
  1989年   17篇
  1988年   14篇
  1987年   17篇
  1986年   15篇
  1985年   5篇
  1984年   4篇
  1983年   3篇
  1982年   10篇
  1981年   10篇
  1980年   3篇
  1979年   9篇
  1978年   3篇
  1977年   4篇
  1976年   6篇
  1975年   7篇
  1973年   2篇
  1972年   4篇
  1971年   2篇
排序方式: 共有1974条查询结果,搜索用时 31 毫秒
21.
The presence of metabotropic receptors for GABA, GABAB, on primary afferent terminals in mammalian spinal cord has been previously reported. In this study we provide further evidence to support this in the rat and show that the GABAB receptor subunits GABAB1 and GABAB2 mRNA and the corresponding subunit proteins are present in the spinal cord and dorsal root ganglion. We also show that the predominant GABAB1 receptor subunit mRNA present in the afferent fibre cell body appears to be the 1a form. In frozen sections of lumbar spinal cord and dorsal root ganglia (DRG) GABAB receptors were labelled with [3H]CGP 62349 or the sections postfixed with paraformaldehyde and subjected to in situ hybridization using oligonucleotides designed to selectively hybridize with the mRNA for GABAB(1a), GABAB(1b) or GABAB2. For immunocytochemistry (ICC), sections were obtained from rats anaesthetized and perfused-fixed with paraformaldehyde. The distribution of binding sites for [3H]CGP 62349 mirrored that previously observed with [3H]GABA at GABAB sites. The density of binding sites was high in the dorsal horn but much lower in the ventral regions. By contrast, the density of mRNA (pan) was more evenly distributed across the laminae of the spinal cord. The density of mRNA detected with the pan probe was high in the DRG and distributed over the neuron cell bodies. This would accord with GABAB receptor protein being formed in the sensory neurons and transported to the primary afferent terminals. Of the GABAB1 mRNA in the DRG, approximately 90% was of the GABAB(1a) form and approximately 10% in the GABAB(1b) form. This would suggest that GABAB(1a) mRNA may be responsible for encoding presynaptic GABAB receptors on primary afferent terminals in a manner similar to that we have previously observed in the cerebellar cortex. GABAB2 mRNA was also evenly distributed across the spinal cord laminae at densities equivalent to those of GABAB1 in the dorsal horn. GABAB2 mRNA was also detected to the same degree within the DRG. Immunocytochemical analysis revealed that GABAB(1a), GABAB(1b) and GABAB2 were all present in the spinal cord. GABAB(1a) labelling appeared to be more dense than GABAB(1b) and within the superficial dorsal horn GABAB(1a) was present in the neuropil whereas GABAB(1b) was associated with cell bodies in this region. Both 1a and 1b immunoreactivity was expressed in motor neurons in lamina IX. GABAB2 immunoreactivity was expressed throughout the spinal cord and was evident within the neuropil of the superficial laminae.  相似文献   
22.
泽泻提取物不同组分对尿草酸钙结石形成的实验研究   总被引:6,自引:0,他引:6  
目的 :研究泽泻提取物不同组分对尿草酸钙结石形成的影响 ,并确定其抑制尿草酸钙结石形成的有效部位。方法 :通过喂服泽泻提取物不同组分对乙二醇和氯化铵诱导的大白鼠肾草酸钙结石模型进行实验研究。结果 :服用泽泻醋酸乙酯浸膏的醋酸乙酯洗脱液大鼠的血清尿素氮 (BUN) ,肌酐 (Cr) ,肾钙 (Ca2+ )含量 ,24h尿Ca2+ 分泌量 ,肾组织的草酸钙晶体沉积均明显低于成石组 (P<0.05)。结论 :泽泻醋酸乙酯浸膏的醋酸乙酯洗脱液能抑制实验性高草酸尿症大白鼠体内肾草酸钙晶体的形成 ,是泽泻抑制尿草酸钙结石形成的有效部位。  相似文献   
23.
喉鳞状细胞癌组织体外原代培养的初步研究   总被引:1,自引:0,他引:1  
目的 应用体外培养技术,对喉鳞状细胞癌组织进行体外培养,探讨喉鳞癌组织原代培养中的各种影响因素,为建立人喉鳞癌组织的细胞系提供实验基础。方法采用体外组织培养技术,对24例人喉鳞状细胞癌组织进行原代培养,观察原代培养中肿瘤细胞的生长与供体的年龄、肿瘤组织的分化程度及不同培养方法的关系,分析在人喉鳞癌细胞的培养中成纤维细胞、微生物污染的影响。结果 24例人喉鳞状细胞癌组织标本,年龄小于60岁组的细胞生长率为31.25%(5/16例),年龄大于60岁组为37.5%(3/8例);高分化组为100%(2/2例),中分化组为30.8%(4/13例),低分化组25%(2/8例);组织块培养法为43.75%(7/16例),酶消化法培养为10%(1/10例);倒置显微镜下观察,在培养的第5~7天,在贴壁组织块周围可见到有上皮样细胞爬出。全部标本中,成纤维细胞的过度生长和微生物的污染是阻碍人喉鳞癌细胞生长的重要因素。结论培养组织的细胞生长率与供体的年龄关系不大;肿瘤组织的分化程度较高者,细胞的生长率较高;与酶消化分离培养法相比,贴壁组织块培养法的细胞生长率较高;成纤维细胞及微生物的污染是阻碍人喉鳞癌细胞系建立的重要因素。  相似文献   
24.
小牛血去蛋白提取物对胃溃疡患者的疗效评价   总被引:2,自引:0,他引:2  
目的:探讨小牛血去蛋白提取物(DCBE)对胃溃疡的治疗作用。方法:选择年龄20~70岁之间,经胃镜检查确诊为活动期胃溃疡的住院患60例。治疗组32例采用静脉滴注DCBE(800mg,qd)和法莫替丁(100mg,bid)治疗;对照组28例采用静脉滴注法莫替丁(100mg,bid)单独治疗。用药2、4wk行胃镜检查,观察自觉缓解症状、时间、愈合率和总有效率。结果:治疗组自觉症状缓解时间明显缩短;给药后2、4wk治疗组及对照组胃镜检查溃疡愈合率分别为78.1%,46.4%及84.4%,71.4%。结论:DCBE能显促进胃溃疡的愈合。  相似文献   
25.
γ射线对大鼠血管平滑肌细胞增殖和周期影响   总被引:2,自引:1,他引:2  
目的:探讨γ射线对大鼠血管平滑肌细胞(VSMCs)抑制作用机理。方法:对大鼠VSMCs进行原代培养,经^3H-TdR掺入法观察γ射线对VSMCs增殖情况影响,应用流式细胞仪检测γ射线对VSMCs细胞周期的影响。采用Western Blot技术检测γ射线对VSMCs p53、细胞周期素D(cyclin D)和增殖细胞核抗原(PCNA)表达的影响。结果:γ射线对寻殖的抑制作用呈剂量依赖性。γ射线照射可诱导VSMCs出现G1期阻滞,在照射后一定时间内会导致p53表达增强,cyclinD和PCNA表达减弱,结论:γ射线可抑制VSMCs增殖,其机制可能主要是γ射线诱导VSMCs出现G1期阻滞,抑制VSMCs进行有丝分裂,在这个过程中p53,cyclinD和PCNA等分子起到一定作用。  相似文献   
26.
Proteus syndrome     
Abstract: This female Asian (Malay) baby had clinical features of Proteus syndrome. She had a large right facial lipolymphangioma with hyperpigmentation of the overlying skin. There was a smaller lymphangioma over the left side of her neck with excess nuchal folds, macrodactyly and bilateral talipes equinovarus. Despite the extensive hemifacial swelling, there was no evidence of upper respiratory tract obstruction. Generalized seizures developed on the sixth day of life which were controlled with phenobarbital. The lymphangiomas were excised without recurrence.  相似文献   
27.
Objectives: A prospective study comparing the efficiacy and side-effects of oral sulindac with intravenous indomethacin in clinically stable preterm infants (<1750 g) requiring non-invasive closure of haemodynamically significant patent ductus arteriosus.
Methodology: As maturity and birthweight are the two major determinants of ductal closure, infants were matched as closely as possible for these parameters. An eligible patient was first assigned to the sulindac group and a subsequent patient with similar gestational age (± 1 week) and birthweight (±100 g) to the previously recruited infant would automatically receive indomethacin. A total of eight infants were enrolled in each group.
Results: The ductus arteriosus was successfully closed in all eight infants receiving indomethacin, and in seven of eight infants receiving sulindac. No significant differences were found with regards to the ductal size between the two groups at diagnosis or on each of the consecutive days of treatment ( P >0.25). More renal adverse effects were encountered in the indomethacin group. Significant differences in changes from baseline value for urine output, plasma sodium, urea and creatinine concentrations were noted at 24, 48 and 72 h after commencement of treatment between the two groups ( P <0.05). All the parameters returned to normal or pre-treatment levels 48 h after stopping therapy. Unexpectedly, severe gastrointestinal complications were encountered in the sulindac group.
Conclusions: Sulindac is capable of promoting ductal constriction in clinically stable preterm infants without compromising the renal function. The spectrum of gastrointestinal complications observed in sulindac treated infants were similar to those described for indomethacin. The use of sulindac for ductal closure in the preterm infant should remain experimental.  相似文献   
28.
Erythromycin treatment for gastrointestinal dysmotility in preterm infants   总被引:3,自引:0,他引:3  
To report our clinical experience on the use of oral erythromycin for the treatment of severe gastrointestinal dysmotility in preterm infants.

Methodology:


A case series study of seven preterm infants (six were very low birthweight) with severe intestinal dysmotility in a tertiary neonatal centre.

Results:


All responded favourably without adverse effects and tolerated full enteral feeding within 1–2 weeks of the commencement of the drug.

Conclusions:


As prolonged total parenteral nutrition carries significant risk of complications, this therapy could be considered in selected preterm infants who fail to establish enteral feeding after an extended period, and in whom an anatomically obstructive lesion of the gastrointestinal tract has been excluded. Meanwhile, we would caution against the widespread implementation of this therapeutic approach until formal evaluation by randomized controlled trials have established the exact role of erythromycin, or its analogues, in the treatment of intestinal dysmotility in preterm infants.  相似文献   
29.
目的分析中国1985-1999年的婚姻挤压方向、程度及变化趋势,为生育保健策略的制定提供依据。方法利用中国2000年第五次人口普查资料,计算男女终身不婚率及婚姻挤压指数。结果中国人口在19851999年15年间一直呈现为男性婚姻挤压,且挤压程度从1991年开始有所升高。结论应重视不能成婚的男性这一弱势群体,开展可行、有效的男性保健;同时,应针对女性开展防范性暴力的健康教育。  相似文献   
30.
目的 探讨抗血管紧张素Ⅱ受体1型(AT1-受体)、α1-肾上腺素受体(α1-受体)、自身抗体是否与慢性肾小球肾炎(CaN)发病有关。方法 以合成的AT1受体和α1受体多肽片段为抗原,应用酶联免疫吸附测定(ELISA)技术,检测66例CGN患者、58例高血压病患者及柏例正常人血清中抗AT1和α1受体自身抗体。结果 CGN肾功能不全组抗AT1和α1受体抗体阳性率分别为56.1%(37/66)和53.0%(36/66),高于高血压无肾损害组(分别为15.5%和12.1%)及正常对照组(分别为10%和12.5%),P〈0.01。结论 抗G蛋白偶联型受体自身抗体可能与慢性肾小球肾炎发病有关。  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