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   3395篇
  免费   372篇
  国内免费   233篇
耳鼻咽喉   18篇
儿科学   20篇
妇产科学   15篇
基础医学   311篇
口腔科学   18篇
临床医学   77篇
内科学   193篇
皮肤病学   74篇
神经病学   76篇
特种医学   51篇
外科学   107篇
综合类   535篇
预防医学   50篇
眼科学   20篇
药学   1356篇
  2篇
中国医学   1046篇
肿瘤学   31篇
  2024年   27篇
  2023年   49篇
  2022年   88篇
  2021年   131篇
  2020年   119篇
  2019年   96篇
  2018年   91篇
  2017年   132篇
  2016年   154篇
  2015年   176篇
  2014年   313篇
  2013年   262篇
  2012年   250篇
  2011年   277篇
  2010年   183篇
  2009年   167篇
  2008年   164篇
  2007年   195篇
  2006年   154篇
  2005年   135篇
  2004年   109篇
  2003年   100篇
  2002年   73篇
  2001年   60篇
  2000年   42篇
  1999年   39篇
  1998年   30篇
  1997年   33篇
  1996年   24篇
  1995年   20篇
  1994年   21篇
  1993年   19篇
  1992年   14篇
  1991年   19篇
  1990年   19篇
  1989年   16篇
  1988年   20篇
  1987年   13篇
  1986年   19篇
  1985年   22篇
  1984年   13篇
  1983年   15篇
  1982年   8篇
  1981年   18篇
  1980年   16篇
  1979年   11篇
  1978年   7篇
  1977年   9篇
  1976年   10篇
  1970年   5篇
排序方式: 共有4000条查询结果,搜索用时 15 毫秒
11.
新生儿隐球菌白化突变化分子机制的初步研究   总被引:1,自引:1,他引:0  
目的:研究新生儿隐球菌白化突变分子机制,方法:采用聚合酶链反应(PCR)技术对新生隐球菌产黑素株与白化突变株进行比较研究,并进行PCR产物的克隆,构建重组表达质粒,转化大肠杆菌。结果:发现白化突变株酚氧化酶结构基因(CNLAC1)在1715-2617bp之间大片段缺失(约450bp),而产黑色素株却无此缺失片菌病的预后和基因治疗提供可能的靶基因。  相似文献   
12.
Primary infiltrating signet ring carcinoma of the eyelids   总被引:1,自引:0,他引:1  
A 61-year old man presented with a five-year history of a swelling initially developing in his right lower lid that progressed to involve the lateral canthal skin and eventually the upper lid and anterior orbit. He was discovered to have an infiltrating, poorly differentiated, mucin-producing carcinoma. Systemic work-up failed to disclose a visceral malignancy, and it was concluded that his tumor was primary in the lids, arising from an adnexal sweat gland. Three other reports in the literature also share almost identical clinical and pathologic features, in that all of the earlier reports dealt with middle-aged or elderly men who had diffusely indurated lids. Histopathologically, the tumor cells grow diffusely in a sclerotic stroma, and resemble the "histiocytoid" variant of metastatic breast carcinoma to the lids in women. Ultrastructural studies in our case point toward an apocrine origin, although earlier authors have favored an eccrine origin. Despite its indolent clinical course, the tumor is capable of producing regional and distant metastases on long-term follow-up. Complete local excision, possibly necessitating radical surgery, is probably the preferred method of treatment, but local radiotherapy may have a beneficial effect in retarding spread of the disease.  相似文献   
13.
Summary Melanosomes and isolated melanosomal fragments (melanin particles) originating from gangliocytes (substantia nigra), astroglia (melanosis cerebelli), and melanocytes (melanotic meningeoma; metastases of melanoblastoma; melanosis thalami of the goat) were compared with synthetic melanins prepared from dopamine and serotonin, respectively. Samples were examined by electron microscopy, X-ray diffraction analysis according to Debye-Scherrer and by infrared spectrophotometry, and the results were evaluated with regard to characteristic features as they may relate to specific cell types or chemical structures.On electron microscopy all three types of melanosomes could be differentiated unequivocally as could the two synthetic melanins. Thus, there were similarities between synthetic melanin from dopamine and the gliogenic melanins of the cerebellum; the synthetic melanin from serotonin resembled melanin of melanocytes.X-ray diffraction analysis yielded 2-4 Debye diffraction rings with all human and synthetic samples, suggesting short range orders between 3.8 to 5 Å the sample obtained from a goat with thalamic melanosis showed a specific reflex pattern. While diffraction patterns of some melanins were partially identical, in particular that of melanin from dopamine and melanin of substantia nigra and dentate nucleus, respectively, they were different for the various melanocytic melanins. Further investigations are required to determine whether these differences are due to disparities in basic chemical structures or conformations or else, to particular compositional features of the various types of melanocytes as they arise from benign or malignant tumors or a specific species.Infrared spectrophotometry at higher wave numbers revealed the well known patterns of melanins, which are not, however, very suitable, for their further differentiation. At lower wave numbers (fingerprinting) melanin of substantia nigra and the glial melanin in melanosis cerebelli yielded additional absorption bands of identical configuration. In contrast to melanin from dopamine, melanin from serotonin exhibited a closely similar absorption pattern in this spectral range, suggesting that the neuroectodermal melanins may contain a component possibly arising from serotonin.
Herrn Prof. Dr. Wilhelm Doerr zum 25. 8. 1979  相似文献   
14.
目的:建立口腔愈疡颗粒的质量标准。方法:采用高效液相色谱法对成品中芍药苷进行含量测定。结果:芍药香浓度线性范围为:0.104—0.520μg/ml,γ=0.9993。样品平均回收率为98.85%,RSD为1.27%(n=5)。结论:该方法适用于口腔愈疡颗粒的质量控制。  相似文献   
15.
目的:研究仙龙方的体内、体外抑癌作用及机理。方法:用 BALB/C 小鼠,荷肝癌和艾氏癌实体瘤,经口给药,观察肿瘤的抑制程度和动物的生存状况。结果:给药组肿瘤生长曲线明显低于对照组。仙龙方还能延长荷瘤动物的生存期,生命延长率为30%~69%。体外实验显示仙龙方对人癌细胞的抑制有一个良好的剂量—效应关系,肝癌的曲线之回归系数 r=0.9983,IC_(50_值为14.8±2.8μg/ml;胃癌曲线的系数 r=0.9995,IC_(50)值为9.7±5.1μg/ml,表明胃癌细胞更敏感些。细胞学研究发现癌细胞的不同程度的损伤、核染色质的凝聚现象及内质网肿胀,流式光度术分析 DNA 组方图上出现了凋亡峰。结论:仙龙方有诱导癌细胞凋亡作用。  相似文献   
16.
目的探讨痹颗粒对RA-MsPGN大鼠模型肾组织PTK活性的影响,治疗RA-MsPGN的作用机制。方法按照Phospho Safe TM ExtR Action Reagent试剂盒提取蛋白质,按照K-LISA PTK Screening Kit试剂盒测定蛋白酪氨酸激酶(PTK)活性,并根据检测试剂盒提供的标准品直线回归方程计算PTKs的含量。结果RA-MsPGN模型大鼠与正常组相比肾组织PTK含量显著升高(P<0.001),雷公藤多苷片和痹颗粒各剂量组均能显著降低大鼠肾组织PTK含量(P<0.05或0.01)。结论痹颗粒对RA-MsPGN大鼠肾组织PTK活性有明显抑制作用,其治疗作用有可能是通过对PTK的作用而实现的。  相似文献   
17.
Hyper-pigmentation is a common, acquired dermatological skin-disorder manifesting and identifiable as irregular brown or greyish-brown facial discolouration, and sometimes referred to as melanosis, melasma or hypermelanosis. Purpose and Objective: To identify the site of melanin deposition in skin-layers regarding facial hyper-pigmentation, based on a histological study of full-thickness skin-facial biopsies in aged Caucasian-cadavers. Hypothesis: Recalcitrant hyper-pigmentation, is chiefly characterised by hyper-melanosis restricted to the dermal-layer of the integument. Method: The histological features of facial hyper-pigmentation and solar-lentigenes were evaluated in a pilot-study of 5-randomly selected Caucasian-cadavers with pigmentation (15 facial biopsies), ranging in age between 75 and 102 years (mean 77-years). Selection-criteria included, both genders, age 〉 75, focal and confluent hyper-pigmented lesions, involving sun-exposed areas of skin (centrifacial, scalp, malar, mandibular and cervical). Study groups included (Grp-1: Control skin-histology in otherwise normal aged, human-cadavers; Grp-2: Histology of pigmented facial skin-lesions in man; Grp-3: Comparative histological skin-controls in non-human primates). No obvious hepatic disease was evident in the cohort studied. Twenty-five histological controls were obtained from non-pigmented areas. Histological evaluation of full-thickness skin-biopsies (including the lesion, edge and peri-]esion skin), was under a Leitz~-light-microscope, and staining included H&E, Masson-trichrome, Masson-fontana, Alcian-blue and Verhoef technology. Histological-scoring used was on histological deposition of melanin in skin-layers: epidermal, dermal, mixed, and indeterminate melanin-deposition (score 1-4). Controls included cadaveric skin-biopsies of human races of colour and non-human primate, Cercopethicus Aethiops (latter is known to have predominantly dermal-melanin deposition). Pigmented and non-pigmented areas were compared in both species. Results: The majority of clinically visible individual and confluent areas of hyper-pigmentation studied were maeroscopically present on the forehead, frontal scalp in hair-receded cadavers, molar and temporal zones. Histologically, documented features of age-related changes without pigment were present in almost all the embalmed cadaver-skins, with a melanin-score of 1. Computer enhanced skin geometry and biometrics confirmed the presence of an aged-skin, pigmentation and features of solar damage. The human embalmed-tissue was well preserved and minimal autolytic changes were present. Special stains of full-thickness biopsies (Masson-Fontana), showed that melanin in the subhuman-primate is lodged in the deep dermis (reticular dermis), within the extra-cellular matrix (ECM) and superficial to the hypodermal adipose-tissue (melanin-score 3). Fifteen pigmented lesions studied in five (5) aged-cadavers (forehead, molar and mandibular areas) all showed predominantly epidermal-deposition of melanin in the basal, suprabasal and stratum corneum with tiny focal areas of dermal melanosis in single-cell macrophages in the papillary-dermis but not reticular-dermis (melanin-score 2). A melanin-deposition localization ratio of epidermis to dermis was approximately 98 to 2% in cadavers with hyper-pigmentation. Conclusion: The skin-strata localization of the melanin with regards hyper-pigmentation of the face and forehead in this aged, human adult Caucasian, cadaveric-study, was predominantly in the epidermis and sparse in the papillary dermis.  相似文献   
18.
目的 因氧氟沙星口服对胃黏膜有刺激作用 ,因此在治疗中往往造成药物性胃炎。本文寻找一种既不影响氧氟沙星疗效 ,又能对抗氧氟沙星破坏胃黏膜作用的理想配伍药物。方法 选择麦滋林 -S(Marzulene -S)及硫糖铝 2种抗溃疡药分别与氧氟沙星配伍使用。结果 麦滋林组的病例与氧氟沙星单独用药组血药浓度相似 (P >0 .0 5 ) ,而硫糖铝组血中氧氟沙星浓度明显低于上述 2组 (P >0 .0 5 )。结论 证明麦滋林 -S颗粒对氧氟沙星血药浓度没有影响 ,且有效保护了胃黏膜免受氧氟沙星的破坏 ;而硫糖铝中所含金属铝离子与喹诺酮类药物形成络合物 ,影响其吸收 ,因而降低了氧氟沙星的疗效  相似文献   
19.
李琴 《当代医学》2014,(2):158-159
目的探究清热益气颗粒治疗支原体性宫颈炎的临床效果。方法回顾性分析2010年5月-2012年12月收治的I20例支原体宫颈炎患者的临床资料,按治疗方式的不同分为观察组和对照组,每组各60例,观察组采用清热益气颗粒治疗,对照组采用西替沙星治疗,比较两组患者经两个疗程治疗后的临床效果。结果观察组治疗有效率为967%,明显优于对照组的76.7%,两组比较,差异有统计学意义(P〈0.05)。结论清热益气颗粒在支原体性宫颈炎患者的临床治疗中作用显著,安全性高,值得临床推广。  相似文献   
20.
目的:观察中西医结合治疗弥漫性轴索损伤的疗效,探讨益气活血冲剂口服后对格拉斯哥(Glasgow)计分的影响。方法将62例弥漫性轴索损伤的患者,随机分为治疗组和对照组,每组各31例,对照组采用常规的脱水降低颅内压、止血药物的运用、护脑治疗及维持水电解质的平衡。治疗组在对照组的基础上加用益气活血冲剂口服,两组疗程一个月,治疗后评定疗效。结果治疗组与对照组治疗前后Glasgow评分组内比较差异有统计学意义(P<0.05);两组治疗后比较,差异有统计学意义(P<0.05);两组总显效率平均为75.16%和35.48%,差异有统计学意义(P<0.05)。结论中西医结合治疗弥漫性轴索损伤有促进患者康复的作用。  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