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   2599篇
  免费   180篇
  国内免费   21篇
耳鼻咽喉   57篇
儿科学   60篇
妇产科学   84篇
基础医学   352篇
口腔科学   22篇
临床医学   245篇
内科学   583篇
皮肤病学   74篇
神经病学   224篇
特种医学   129篇
外科学   331篇
综合类   19篇
预防医学   206篇
眼科学   16篇
药学   197篇
中国医学   1篇
肿瘤学   200篇
  2023年   13篇
  2022年   19篇
  2021年   37篇
  2020年   42篇
  2019年   56篇
  2018年   58篇
  2017年   50篇
  2016年   51篇
  2015年   48篇
  2014年   71篇
  2013年   109篇
  2012年   120篇
  2011年   119篇
  2010年   93篇
  2009年   84篇
  2008年   110篇
  2007年   110篇
  2006年   99篇
  2005年   95篇
  2004年   83篇
  2003年   74篇
  2002年   55篇
  2001年   82篇
  2000年   81篇
  1999年   71篇
  1998年   43篇
  1997年   29篇
  1996年   35篇
  1995年   30篇
  1994年   43篇
  1993年   45篇
  1992年   65篇
  1991年   52篇
  1990年   47篇
  1989年   53篇
  1988年   42篇
  1987年   48篇
  1986年   48篇
  1985年   48篇
  1984年   35篇
  1983年   38篇
  1982年   22篇
  1981年   31篇
  1980年   15篇
  1979年   19篇
  1978年   33篇
  1977年   22篇
  1976年   15篇
  1975年   16篇
  1974年   28篇
排序方式: 共有2800条查询结果,搜索用时 15 毫秒
1.
2.
3.
The purpose of the study was to compare skin blood flow by laser Doppler flowmetry (LDF) and the 133-Xenon washout technique in UVB-inflamed human skin. Six healthy subjects participated in the study. Forearm skin blood flow was measured prior to irradiation and then 8, 24, 48 and 72 h after the exposure to twice the minimal erythema dose of UVB. Baseline blood flow as measured by the 133-Xenon washout method was 5.2 (range 3.0 to 10.4) ml/100g/min and LDF flux was 3.1 (range 2.7 to 5.7) arbitrary units. Following irradiation, maximum blood flow increase as evaluated by the 133-Xenon washout was 10.8 (95% confidence interval 3.7 to 11.3) times baseline blood flow, corresponding to an absolute blood flow of 47.5 (range 33.8 to 56.3) ml/100g/min. Maximum increase after induction of inflammation as assessed by LDF was 34.6 (95% confidence interval 24.6 to 56.5) times baseline flux. The two methods showed comparable time courses in all subjects. A significant correlation between the two methods was found, Spearman's rho = 0.54, p = 0.006. The relative LDF blood flow increase was 4.2-fold (95% confidence interval 2.7 to 5.0) greater than the increase measured by the 133-Xenon washout method. These results are at variance with previous comparative studies of the two methods. Some explanations are discussed.  相似文献   
4.
Background: Neuropathic pain in spinal cord injury is a common challenging therapeutic condition. The current study examines the analgesic effect of the sodium channel blocker lidocaine on neuropathic pain in patients with spinal cord injury and the predictive role of concomitant evoked pain on pain relief with lidocaine.

Methods: Twenty-four spinal cord injury patients with neuropathic pain at or below the level of injury were randomized and completed a double-blind crossover trial of 5 mg/kg lidocaine and placebo infused over 30 min. Twelve patients reported evoked pain, and 12 patients had no evoked pain. Spontaneous and evoked pains were assessed using a visual analog scale and quantitative sensory testing.

Results: Lidocaine significantly reduced spontaneous pain in all patients (P < 0.01) and in each of the two groups with (P < 0.01) and without (P = 0.048) evoked pain, with no difference in number of responders (pain reduction >= 33%) between the patients with (n = 6) and without (n = 5) evoked pain. Lidocaine significantly relieved both at-level and below-level neuropathic pain and decreased brush-evoked dysesthesia but not cold allodynia, pinprick hyperalgesia, or pain evoked by repetitive pinprick.  相似文献   

5.
BACKGROUND: Acute respiratory infections (ARIs) are an important cause of infant morbidity in both developing and developed countries, and they are the leading cause of death in poorer parts of the world. Respiratory viruses appear to be the most frequent microbiological pathogens, especially respiratory syncytial virus. It has been suggested that factors such as being male, overcrowding, poor access to medical care, low level of maternal education, and passive smoking are associated with contracting ARIs. DESIGN: A fixed birth cohort of 571 children was followed from birth to 1 year of age. The children were monitored for symptoms of ARIs during regular home visits. SETTING: An urban low-income setting in Soweto, a township outside Johannesburg with an estimated 1.2 million inhabitants, including an estimated 45,000 children under 2 years of age. SUBJECTS: A total of 571 children were observed for 118,650 days. OUTCOME MEASURES: The incidence rate of ARIs. The determinants birth weight, breastfeeding, gender, crowding, passive smoking, indoor pollution, and sanitary facilities were analysed. RESULTS: A total of 489 episodes of coughing or coughing and nasal discharge combined were recorded. Only the father's level of education and the number of people living in the household remained significant in the multivariate analyses. The incidence of severe ARIs was reduced among breastfed infants. CONCLUSIONS: Our study supports previous observations suggesting that crowding and communal living conditions are important determinants of ARIs. Breastfeeding seemed protective against severe ARI. The lack of association with well-described risk factors such as low level of maternal education, gender and passive smoking could be due to lack of statistical power in this rather uniform population.  相似文献   
6.
7.
OBJECTIVE: To test whether healthcare workers' knowledge of and compliance with the basic principle of the Universal Precautions policy (i.e., that all patients should be treated equally regarding contact with body fluids) influenced the rate of contact with patient blood. DESIGN: Survey based on anonymous questionnaires. SETTING: A 380-bed secondary and tertiary care hospital receiving emergency and elective patients. PARTICIPANTS: All employees having any contact with patients. Nine hundred one of 1,308 (69%) of the questionnaires were returned. RESULTS: Twelve percent of the respondents (95% confidence interval [CI95] = 10.0%-14.4%) had experienced any contact with patient blood in the week preceding their answer. Physicians had the highest rate of contact with blood followed by nurses. In the five groups--physicians, nurses, laboratory technicians and phlebotomists, nursing aides, and student nurses--contact with blood was less frequent in the subgroup that did know and comply with the basic principle of the Universal Precautions policy, compared with the subgroup that did not. When adding the results for the 5 groups, contact with blood was experienced by 91 of 571 (15.9%, CI95 = 13%-19%) of the personnel who did not know and comply with Universal Precautions. The personnel who did know and comply with Universal Precautions had a significantly lower (9 of 111 [8.1%], p < .05, CI95 = 3.8%-15%) rate of contact with blood. CONCLUSIONS: The healthcare workers who knew and complied with Universal Precautions had a significant lower rate of contact with patient blood than those who did not.  相似文献   
8.
A case of a muscular hamartoma of the breast in a 47-year-old woman is presented. Tumors containing smooth muscle are rare in the breast. Radiologically it appears as a circumscribed tumor with homogeneous or varying density. Histologically these lesions are composed of ducts, lobules, stroma prominently adipose, and smooth muscle.  相似文献   
9.
目的 探索LDH实验检测细胞活力的可行性。方法 原代培养骨髓细胞和软骨细胞,用LDH实验测定上述两组细胞的活力,并与镜下活体观察到细胞的生长状况相比较。与目前比较成熟的测定细胞活力的MTS实验的测得的值相比较。结果 LDH实验对上述两组细胞的活力的测定结果与镜下活体观察到的结果相符合。与MTS实验的测得的结果经统计学处理无显著差异。结论 LDH实验可用于细胞活力的直接测定,而对活细胞的生存、繁殖无影响。  相似文献   
10.
During the last year we developed a disposable anal plug electrode for pelvic floor/external anal sphincter electromyography. The electrode consists of 2 disposable silver chloride surface electrodes mounted on a trochlear-shaped sponge. Testing of the new electrode with simultaneous registration of external anal sphincter electromyography using a coaxial needle electrode showed synchronous electromyographic patterns. In clinical urodynamic studies, including 48 cystometry studies with anal sphincter electromyography and 48 pressure-flow electromyographic studies, the electrode provided technically good and reliable electromyograms. The electrode design secures good contact to the recording surface and a safe fixation of the electrode during recording. The compressibility of the electrode might circumvent the problem of possible detrusor reflex inhibition induced by conventional hard anal plug electrodes. We recommend this technique for anal sphincter electromyography, since it is simple, reliable and without discomfort, and it does not require sterilization of the electrode.  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