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   10667篇
  免费   1149篇
  国内免费   211篇
耳鼻咽喉   103篇
儿科学   316篇
妇产科学   79篇
基础医学   855篇
口腔科学   356篇
临床医学   1487篇
内科学   1899篇
皮肤病学   213篇
神经病学   1186篇
特种医学   178篇
外国民族医学   1篇
外科学   848篇
综合类   995篇
预防医学   1712篇
眼科学   128篇
药学   909篇
  4篇
中国医学   203篇
肿瘤学   555篇
  2024年   44篇
  2023年   299篇
  2022年   425篇
  2021年   604篇
  2020年   585篇
  2019年   575篇
  2018年   496篇
  2017年   448篇
  2016年   447篇
  2015年   405篇
  2014年   629篇
  2013年   808篇
  2012年   473篇
  2011年   518篇
  2010年   511篇
  2009年   448篇
  2008年   450篇
  2007年   475篇
  2006年   389篇
  2005年   306篇
  2004年   276篇
  2003年   232篇
  2002年   204篇
  2001年   196篇
  2000年   143篇
  1999年   117篇
  1998年   116篇
  1997年   98篇
  1996年   108篇
  1995年   112篇
  1994年   103篇
  1993年   85篇
  1992年   90篇
  1991年   96篇
  1990年   95篇
  1989年   83篇
  1988年   72篇
  1987年   67篇
  1986年   74篇
  1985年   88篇
  1984年   73篇
  1983年   21篇
  1982年   34篇
  1981年   28篇
  1980年   18篇
  1979年   16篇
  1978年   9篇
  1977年   11篇
  1976年   9篇
  1975年   6篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
Substance P and human nasal mucociliary activity   总被引:2,自引:0,他引:2  
Summary Substance P (SP), a potent inflammatory agent, has been found in sensory nerve fibres in the nasal mucosa in several experimental animals as well as in man. It may participate in the inflammatory response as part of the mucosal defence against foreign materials. In experimental animals SP has been found to increase mucociliary in airway mucosa. The present study was performed in order to find out the relationship between topically applied SP and nasal mucociliary function in humans. Thirteen healthy volunteers were challenged with 65 µg SP or placebo in a randomized cross over fashion and mucociliary transport time was determined each time using the saccharine dye test. The dose of SP was chosen after an open dose-response study. No statistically significant change in the mucociliary transport time was found after challenge with SP as compared to placebo. The possible reasons for this are discussed.  相似文献   
22.
The question of whether functional residual capacity (FRC) falls in infants during active sleep has been clouded by studies using different subject groups and techniques for measurements of lung volume and determination of sleep state. Twenty healthy full-term infants within the first week of life participated in the present study. Neurophysiological and behavioral criteria were used to define sleep state, and measurements of FRC were made using a specially constructed closed-circuit helium dilution system. Regularity of respiration was recorded using magnetometers on the chest and a modified respirator monitor. Results showed that no significant changes in FRC occurred, related either to sleep state or to regularity of respiration. In addition, we failed to detect any differences in FRC between the sexes. Pediatr Pilmonol. 1989; 7:71–77 .  相似文献   
23.
The immunohistochemical occurrence of the high affinity neurotrophin (NT) receptors trkA, trkB, and trkC is shown in the pre-term newborn, infant, and adult human post-mortem cerebellum. Immunoreactive neuronal perikarya and processes were observed in all specimens examined, where they appeared unevenly distributed in the cerebellar cortical layers and deep nuclei, and showed regional differences among cerebellar lobules and folia. The trk receptor-antibodies, tested by Western blot on human cerebellum homogenates, revealed multiple immunoreactive bands for trkA and single bands for trkB and trkC. The results obtained show the tissue localization of the trk receptor-like immunoreactivity in the human cerebellum from prenatal to adult age. The analysis for codistribution of the receptors with the relevant ligand and among the receptors in discrete cortical and deep nuclei tissue fields shows a wide variety of conditions, from a good similarity in terms of type and density of labeled structures, to a lack of correspondence, and suggests the possibility of colocalization of trk receptors with the relevant neurotrophin and among them in the cerebellar cortex. These results sustain the concept that the neurotrophin trophic system participates in the development, differentiation, and maintenance of the human cerebellar connectivity and support the possibility of a multifactorial trophic support for the neurotrophins through target-derived and local mechanisms.  相似文献   
24.
Summary Eight healthy volunteers participated in an open crossover study to assess the effect of a standardised meal on the systemic availability of a single oral dose of fenoldopam mesylate 100 mg. Subjects were studied on four separate occasions, twice fasting and twice fed in randomised, balanced order. Plasma and urine samples were obtained before and at regular intervals up to 25 h post dose. Measurement of fenoldopam (SK&F 82526) and its 8-sulphate metabolite (SK&F 87782) were by means of HPLC-EC analysis. Area under the plasma concentration time curve (AUC) and maximum detected plasma concentration (Cmax) for fenoldopam and SK&F 87782 were significantly reduced whereas time to maximum concentration was significantly increased with food. Using AUC's for fenoldopam and SK&F 87782, mean relative bioavailabilities were 35% and 81% respectively under fed compared with fasting conditions. Twenty-four hour excretion of fenoldopam was significantly reduced with food, but excretion of SK&F 87782 was apparently unchanged. Mean relative bioavailabilities calculated from these data were 83% and 86% respectively. Relatively large inter-subject variability in AUC and Cmax were seen, but intra-subject variability was not marked. Mild symptoms associated with vasodilation were reported on all study days.  相似文献   
25.
目的 探讨压力调节容量控制(PRVC)通气模式对健康及急性肺损伤(ALI)模型犬的血流动力学、呼吸力学和呼吸功能的影响。方法 PRVC和间歇正压通气(IPPV)两种通气模式在呼气末压为0、0.5、1.0和1.5kPa时,分别测定健康犬及油酸诱发ALI犬的血流动力学、呼吸力学及血气参数。结果 健康犬PRVC较IPPV模式下除了在PEEP为0.5kPa时,气道峰压(PIP)、肺动态顺应性(Cdyn)和肺血管阻力(PVR)的影响差异有显著性,对血流动力学、呼吸力学及呼吸功能的影响差异均无显著性。ALI犬PRVC较IPPV模式下各PEEP水平的PIP、平均气道压(mPaw)、Cdyn、动脉血氧分压[pa(O2)]和氧耗(VO2)的影响均有显著意义,但两种通气模式对血流动力学的影响差异无显著性。结论 与IPPV相比,PRVC通气模式能降低PIP,增加Cdyn和提高pa(O2),两模式对血流动力学的影响差异无显著性,PRVC更适用于ALI/ARDS的治疗。  相似文献   
26.
目的 探讨氯喹对全肝缺血再灌注大鼠急性肺损伤(Au)的保护作用及其机制。方法 健康SD大鼠90只,雌雄不拘,体重300~350g,随机分为3组:假手术组(A组)、全肝缺血再灌注组(B组)、全肝缺血再灌注+氯喹组(C组),每组30只。阻断肝门及肝上、肝下下腔静脉20min时开放血流,建立大鼠全肝缺血再灌注模型。C组于缺血前即刻经股静脉注射氯喹10mg/kg,A、B组给予等量生理盐水。于缺血20min、再灌注4h时每组分别处死10只大鼠,抽取门静脉血,测定血浆D-乳酸、内毒素(ETX)、肿瘤坏死因子-a(TNF-a)浓度,另外10只用于观察再灌注48h时大鼠生存率,并在电镜下观察肺组织超微结构的改变。结果 缺血再灌注可导致大鼠缺血期和再灌注期门静脉血D-乳酸、ETX、TNF-a浓度升高,大鼠生存率降低,肺组织超微结构严重受损,氯喹可减弱全肝缺血再灌注导致的上述改变。结论 氯喹对全肝缺血再灌注大鼠ALI有一定的保护作用,通过抑制磷脂酶A2激活,降低肠粘膜屏障通透性升高,降低肠黏膜内毒素移位。  相似文献   
27.
We report here an unusual case of fibrous histiocytoma in which an area of xanthogranuloma was observed histologically. Our case suggests that adult xanthogranuloma is a variant of fibrous histiocytoma.  相似文献   
28.
Summary The disposition of the enantiomers of MK-571 (MK-0679 and L-668,018) following single i. v. doses of MK-571 (L-660,711) was studied in a three way cross-over study in 12 healthy male volunteers. Each volunteer received 75 mg, 300 mg and 600 mg i. v. doses of MK-571 at weekly intervals.The disposition of both enantiomers appeared dose-dependent, since the AUC increased disproportionately faster than the dose. The dose dependency was much more pronounced for L-668,018: its AUC increased 6-fold from the 75 to the 300 mg dose, 16-fold from 75 to 600 mg and 2.7 fold from 300 to 600 mg. For MK-0679, the corresponding increases in AUC were 4.8-, ll-, and 2.3 fold. Regardless of dose, the elimination of L-668,018 was more rapid than that of MK-0679.The disposition of MK-0679 needs to be investigated independently to detect any potential influence of L-668,018 on its disposition.  相似文献   
29.
报告了成人结核性脑膜炎11例误诊,并收集国内报告的221例误诊病例,对结核性脑膜炎的误诊原因进行了综合分析。  相似文献   
30.
深圳市龙岗区坪地外来工亚健康状态的研究   总被引:5,自引:0,他引:5  
目的 :探讨深圳市龙岗区坪地外来工亚健康状况及其影响因素 ,为预防亚健康提供科学依据。方法 :采用统一表格对 12 68深圳市龙岗区坪地外来工进行调查。结果 :外来工的平均年龄为 ( 2 4.96± 6.10 )a ,其亚健康状态总体发生率为 65 .3 0 %,男性亚健康状态发生率为 63 .2 1%,女性为 67.91%,男性和女性之间差异无统计学意义。亚健康状态主要影响因素为 :结婚与否、睡眠时间、工作时间、加班时间以及工作是否有压力和居住环境差等因素 ,而与吸烟、饮酒、文化程度等因素无相关。结论 :深圳龙岗区坪地外来工中普遍存在亚健康状态 ,其发生较高且与工作环境、工作时间、加班时间有密切关系 ,故应引起政府部门及社会各界高度重视 ,加强对外来工的健康保护  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