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   784篇
  免费   83篇
  国内免费   60篇
耳鼻咽喉   2篇
儿科学   41篇
妇产科学   7篇
基础医学   123篇
口腔科学   25篇
临床医学   143篇
内科学   179篇
皮肤病学   15篇
神经病学   50篇
特种医学   89篇
外科学   66篇
综合类   20篇
预防医学   49篇
眼科学   5篇
药学   74篇
中国医学   2篇
肿瘤学   37篇
  2021年   5篇
  2019年   10篇
  2018年   11篇
  2017年   5篇
  2016年   13篇
  2015年   14篇
  2014年   25篇
  2013年   29篇
  2012年   17篇
  2011年   15篇
  2010年   35篇
  2009年   32篇
  2008年   40篇
  2007年   67篇
  2006年   32篇
  2005年   33篇
  2004年   31篇
  2003年   22篇
  2002年   22篇
  2001年   18篇
  2000年   15篇
  1999年   21篇
  1998年   35篇
  1997年   38篇
  1996年   25篇
  1995年   24篇
  1994年   32篇
  1993年   21篇
  1992年   13篇
  1991年   14篇
  1990年   6篇
  1989年   22篇
  1988年   20篇
  1987年   13篇
  1986年   8篇
  1985年   15篇
  1984年   10篇
  1983年   8篇
  1982年   13篇
  1981年   12篇
  1980年   9篇
  1978年   7篇
  1977年   8篇
  1976年   11篇
  1975年   9篇
  1973年   7篇
  1972年   4篇
  1971年   3篇
  1970年   8篇
  1969年   4篇
排序方式: 共有927条查询结果,搜索用时 15 毫秒
921.
SUMMARY The incidence of climacteric symptoms was determined in 247 healthy premenopausal women in a community setting. These volunteers had been recruited to a longitudinal study of bone density. Of these subjects, 46 ceased to menstruate during the study, and in this subgroup symptoms were compared before and after cessation of menstruation. Only hot flushes increased after cessation of menstruation in the longitudinal study and showed age correlation in the cross-sectional study. Hot flushes thus emerged as a true menopausal symptom. Although evidence for this is weaker, cold sweats and suffocation seem likely to be genuinely menopausal. Breast discomfort and the four mood symptoms of irritability, excitability, depression and poor concentration improved after cessation of menstruation, and this study gives no support for their being part of the menopausal syndrome; it suggests that these symptoms are more likely to be related to menstruation than to the menopause.  相似文献   
922.
Rowley  JD; Golomb  HM; Vardiman  JW 《Blood》1981,58(4):759-767
Cytogenetic studies were performed on 26 patients who developed acute nonlymphocytic leukemia (ANLL) or a dysmyelopoietic syndrome after treatment of a primary malignancy. Fifteen patients had radiotherapy and chemotherapy, seven had only chemotherapy, and four had only radiotherapy. The median times from diagnosis of the initial disease to the development of bone marrow dysfunction for these treatment groups were 50, 46, and 49 mo, respectively. Twenty-five patients had an abnormal karyotype in myeloid cells. Loss of part or all of no. 5 and/or no. 7 was noted in 23 of 25 patients with aneuploidy. Loss of no. 5 was noted only in patients who previously had malignant lymphoma, whereas loss of no. 7 was seen in these patients as well as in those who had other malignancies. Abnormalities of both nos. 5 and 7 occurred in 53% of the patients treated with combined therapy and in only 27% of patients treated with either modality alone. Although these changes are distinctly different from those noted in lymphomas, they are similar to those seen in 25% of aneuploid patients with ANLL de novo.  相似文献   
923.
MacGregor EA  Dowson A  Davies PT 《Headache》2002,42(4):249-255
OBJECTIVE: To compare the efficacy of mouth-dispersible aspirin 900 mg and placebo in the treatment of migraine. BACKGROUND: Aspirin is widely accepted as an effective therapy for migraine. Previous studies have indicated that gastric stasis and delayed gastric emptying, which occur during migraine attacks, delay aspirin absorption. Mouth-dispersible formulations are considered to be more quickly absorbed than solid formulations and, therefore, may be more effective in treating migraine. DESIGN: Randomized, double-blind, placebo-controlled, crossover study in four specialized migraine clinics in the United Kingdom. METHODS: One hundred one patients diagnosed with migraine (according to the International Headache Society diagnostic criteria) participated in the study. Patients received either single doses of mouth-dispersible aspirin (3 x 300 mg) or placebo for moderate pain in the treatment of two migraine attacks. Rescue medication could be taken after 2 hours, if required. The primary efficacy parameter was response to therapy at 2 hours posttreatment. Other efficacy parameters were response to treatment, pain-free, and pain intensity at all other time points. Functional disability, nausea, vomiting, photophobia, phonophobia, symptom relief, patient and investigator global evaluation, use of rescue medication, headache recurrence, and palatability and convenience were also recorded. RESULTS: Of 101 patients, 73 took both treatments. At 2 hours, 48% of patients taking mouth-dispersible aspirin responded, compared to only 19% taking placebo (P =.0005). Mouth-dispersible aspirin was significantly better than placebo for response to treatment (P<.05) and pain intensity difference (P<.01) at all time points from 30 minutes posttreatment; for pain-free (P<.05) and use of rescue medication (P<.01) from 3 hours posttreatment; for headache recurrence (P<.05); and for patients' and investigators' global evaluations of efficacy (P =.0001 in both cases). CONCLUSIONS: Mouth-dispersible aspirin 900 mg is effective compared with placebo for the treatment of moderate migraine head pain, with relief seen from as early as 30 minutes after taking medication.  相似文献   
924.
<正>To the Editor: Hypoxic hepatitis(HH), also known as ischemic hepatitis or shock liver, is a liver injury characterized by necrosis of centrilobular hepatocytes with a rapid increase in serum aminotransferase levels. The incidence rate of HH among patients in the intensive care unit(ICU) was found to be 0.9%-11.9% [1]. Occurrence of HH appears to have a significant impact on the clinical outcome.  相似文献   
925.
输入病人体内的血小板的循环能力和功能与体外保存损害和受者的体内环境有关。患有血小板减少症的住院病人,体内影响血小板存活和功能的因素比体外保存损害的影响更重要。然而人们长久以来一直认为,预测血小板成分在体内的作用可以为现行的输血措施提供有价值的参考,也可能进一步提高临床疗效,同时更有效的管理血小板贮存。确实,新的病原菌灭活方法推动了临床应用,同时可能使浓缩血小板保存更安全、保存时间更长,精确评定临床有意义的浓缩血小板质量。 保存血小板在输血后的存活和功能差异较大。如果血小板处理小心,也没有长时间保存(采集后24—48小时内)便很快  相似文献   
926.
Burkholderia multivorans is a prominent B. cepacia complex (BCC) species causing infection in people with cystic fibrosis. Despite infection control measures being introduced to reduce the spread of BCC there is a continued emergence of infections by B. multivorans. Our objective was to analyze a global collection of B. multivorans isolates, comparing those from environmental and clinical sources with those from reported outbreaks. Multilocus sequence typing (MLST) was performed on 107 B. multivorans isolates to provide a detailed analysis of the global population biology of this species. MLST resolved 64 B. multivorans sequence types. Twelve of these were globally distributed and associated with human infection; two of these (ST-21 and ST-375) were also composed of environmental isolates. These global lineages included strains previously linked to large outbreaks (e.g., French epidemic clone ST-16). Though few environmental isolates of B. multivorans were available for analysis, of six strains identified, three were identical to strains recovered from cystic fibrosis (CF) infection. Although the ability of B. multivorans to cause CF outbreaks is known, our report here concerning the existence of globally distributed B. multivorans CF strains is a new observation for this emerging B. cepacia complex pathogen and suggests that certain strain types may be better adapted to human infection than others. Common transmission-associated risk factors were not obviously linked to the globally distributed strains; however, the overlap in strains recovered from water environments, industrial products, and human infection suggests that environmental sources may be an important reservoir for infection with B. multivorans.  相似文献   
927.
目的通过观察香烟提取物对牛冠状动脉内皮细胞(BCAEC)的损伤作用,为研究吸烟与心血管疾病之间的关系提供依据。方法以吸烟者体内通常的尼古丁浓度为基准,分别用尼古丁、香烟主流烟雾提取物(MSW)和侧流烟雾提取物(SSW)对 BCAEC 进行染毒(尼古丁染毒终浓度分别为1×10~(-5)、0.8×10~(-5)、0.9×10~(-5)mol/L),用显微数码成像系统记录细胞形态变化,检测凋亡细胞与坏死细胞的发生比例,测定 caspase 酶活力。结果经尼古丁、MSW 处理的 BCAEC 形态上发生凋亡样变化,处理24 h 后凋亡细胞发生率为5.89%和11.94%。而 SSW 处理后的 BCAEC 呈坏死样变化.处理24 h 后62.84%的细胞发生坏死。尼古丁和 MSW 可诱导 caspase-3活力增高。结论香烟提取物可诱导牛冠状动脉内皮细胞损伤,MSW 可引起细胞凋亡,SSW 导致细胞坏死,caspase-3的激活可能是香烟提取物诱导牛冠状动脉内皮细胞凋亡的机制。  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