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   9876篇
  免费   779篇
  国内免费   25篇
耳鼻咽喉   105篇
儿科学   266篇
妇产科学   160篇
基础医学   1795篇
口腔科学   313篇
临床医学   794篇
内科学   2021篇
皮肤病学   111篇
神经病学   734篇
特种医学   270篇
外科学   1521篇
综合类   58篇
一般理论   3篇
预防医学   712篇
眼科学   87篇
药学   982篇
中国医学   9篇
肿瘤学   739篇
  2023年   42篇
  2022年   89篇
  2021年   153篇
  2020年   137篇
  2019年   171篇
  2018年   173篇
  2017年   193篇
  2016年   185篇
  2015年   185篇
  2014年   268篇
  2013年   423篇
  2012年   540篇
  2011年   571篇
  2010年   322篇
  2009年   327篇
  2008年   496篇
  2007年   500篇
  2006年   485篇
  2005年   448篇
  2004年   385篇
  2003年   389篇
  2002年   370篇
  2001年   262篇
  2000年   311篇
  1999年   266篇
  1998年   125篇
  1997年   115篇
  1996年   85篇
  1995年   99篇
  1994年   84篇
  1993年   73篇
  1992年   228篇
  1991年   212篇
  1990年   210篇
  1989年   194篇
  1988年   151篇
  1987年   176篇
  1986年   146篇
  1985年   123篇
  1984年   119篇
  1983年   103篇
  1982年   68篇
  1981年   57篇
  1980年   49篇
  1979年   88篇
  1978年   78篇
  1977年   54篇
  1974年   52篇
  1973年   42篇
  1972年   41篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
Summary The objective of this study was to investigate if the dust in a mill producing soft paper tissue caused respiratory symptoms or impaired respiratory function. Using a questionnaire and spirometry, 355 persons were examined. They were divided into three groups according to present exposure to dust; low (< 1 mg/m3), moderate (1–5 mg/m3) and heavy (> 5 mg/m3). There was a dose-dependent increase of symptoms from the upper respiratory tract. However, coughing and coughing with phlegm were not found to be more common among persons with heavy exposure compared to those with low exposure to the dust. There was no difference in FEV, or FVC during a work shift. Persons with long-term (> 10 years) and heavy exposure to dust seemed to have impaired respiratory function compared to those with low and/or short-term exposure to the dust.  相似文献   
32.
Zebrafish (Danio rerio) were orally exposed to a mixture of 20 PCBs in three different dose levels (0.008, 0.08, and 0.4 μg of each congener per gram of freeze-dried chironomids). Generally, the PCBs accumulated in a dose-related manner. After 13 weeks of exposure body, liver, and ovary weights, as well as the liver and ovary somatic index, were significantly lower in exposed groups. In addition, the PCB mixture was an effective inducer of hepatic EROD activity. The reproduction study performed with exposed females and unexposed males after 9 weeks revealed that median survival time for larvae was only 7.7 days in the high-dose group as compared with 14 days in controls. Furthermore, egg production was reduced in all three groups exposed. No differences in hatching frequency or median hatching time were recorded. Histologically, females in both the intermediate and high-dose groups contained a reduced number of mature oocytes. The present study demonstrates that the potency of the mixture of selected PCBs induces hepatic EROD activity and has a clearly negative effect on zebrafish reproduction. Received: 7 May 1997/Accepted: 29 November 1997  相似文献   
33.
Hereditary lymphedemas that are not associated with other malformations usually affect the lower limbs and are inherited in an autosomal dominant fashion. These non-syndromic hereditary lymphedemas are categorized by their age of onset, being either congenital (Milroy disease) or having an onset in childhood or around puberty (Meige disease). We describe a family in which three individuals in three generations had unusually late onset of lym-phedema in their mid-twenties or thirties. The proband additionally developed a very rare lymphangiosarcoma. This tumor, usually associated with post-mastectomy lym-phedema, has not been described in late-onset hereditary lymphedema. Because of an unusually high incidence of multiple primary tumors in association with lymphangiosarcoma in the literature (approximately 10%) and the proband's own familial cancer background, we speculate that an inherited predisposition to malignancy may underlie the development of lymphedema-associated lymphangiosarcoma. © 1995 Wiley-Liss, Inc.  相似文献   
34.
The aim of this study was to test the inter-rater reliability of a revised oral assessment guide (ROAG) for patients residing in a geriatric rehabilitation ward. A consecutive sample of 140 patients was recruited for the study. Oral assessments were performed for 133 newly admitted patients by one registered nurse (RN) during a period of six months. A dental hygienist (DH) carried out 103 oral assessments during the same half-year. For 66 patients, the RN and the DH performed independent assessments. There was an agreement between the RN and the DH in the majority of the independent assessments, except for tongue and teeth/dentures. The percentage agreement exceeded 80 percent. Inter-rater agreement measured by Cohen's Kappa coefficient ranged from moderate to very good and percentage agreement had a range of 58 to 91 percent. The agreement was highest in assessment of voice and swallowing (91%). Assessments of teeth and dentures seemed to be most difficult for the RN to evaluate. ROAG was found to be a clinically useful assessment tool. Additional education and training is needed to improve the reliability of the oral assessments and should include continuous support from a dental hygienist as well as a pictorial manual on how to use the ROAG.  相似文献   
35.
The aim of this study was to investigate markers of serotonin and immune function in suicidal patients. Cytotoxic activity of natural killer cells (NK) and CD16 lymphocytes were studied in 28 suicide attempters and 26 healthy controls, and related in patients to 5-hydroxyindoleacetic acid (5-HIAA) in cerebrospinal fluid (CSF). Patients with CSF 5-HIAA below the median had significantly lower NK cell activity than other patients. CD16 cell frequency was significantly lower in patients than in controls, and patients also tended to have lower NK cell cytotoxicity than healthy controls. There were no statistically significant correlations between 4-hydroxy-3methoxyphenyl glycol (HMPG), homovanillic acid (HVA), CSF cortisol and NK cell activity. The results support the hypothesis of compromised immune function in suicidal patients with evidence of disordered serotonin function.  相似文献   
36.
37.
Treatment with flurbiprofen (100 mg twice a day for 5 days), tranexamic acid (1.5 gm three times a day for 3 days and 1 gm twice a day for another 2 days), and an intrauterine contraceptive device releasing 20 micrograms levonorgestrel per day was compared in women with idiopathic menorrhagia. The menstrual blood loss during two control periods in 15 women subsequently treated with flurbiprofen and tranexamic acid was 295 +/- 52 ml and 203 +/- 25.2 ml in the 16 women later fitted with a levonorgestrel-releasing intrauterine contraceptive device. Menstrual blood loss was reduced by all three forms of treatment. The reduction in menstrual blood loss expressed as a percentage of the mean of two control cycles for each form of treatment was as follows: flurbiprofen, 20.7% +/- 9.9%; tranexamic acid, 44.4% +/- 8.3%; levonorgestrel-releasing intrauterine contraceptive device after 3 months, 81.6% +/- 4.5%; levonorgestrel-releasing intrauterine contraceptive device after 6 months, 88.0% +/- 3.1%; levonorgestrel-releasing intrauterine contraceptive device after 12 months, 95.8% +/- 1.2%. The reduction in menstrual blood loss achieved by the levonorgestrel-releasing intrauterine contraceptive device was greater than that recorded with flurbiprofen (p less than 0.001) and tranexamic acid (p less than 0.01), and was greater for tranexamic acid when compared with flurbiprofen (p less than 0.05). The levonorgestrel-releasing intrauterine contraceptive device was the only form of treatment to reduce mean menstrual blood loss below 80 ml per menstruation, the upper limit of normal menstrual blood loss.  相似文献   
38.
An axillary brachial plexus nerve block by a transarterial approach is commonly used to achieve regional anaesthesia for hand surgery. We designed a retrospective study to evaluate efficacy and safety of the technique for acute and elective operations. Anaesthetic records of 189 of all 5520 patients (1996-2000) who had axillary brachial plexus blocks for hand surgery were reviewed, and results compared with complications recorded in the anaesthetic register and in the hand surgery records. Successful axillary block was achieved in 5128/5520 (93%) of patients, according to anaesthetic charts, and primarily in 157/189 (83%), and after supplementation in 171/189 (90%), according to anaesthetic records. Four patients had a toxic drug reaction or axillary haematoma with a transient neurological deficit. Medical complications were recorded in the anaesthetic register in less than 0.7% of axillary brachial plexus procedures. Axillary brachial plexus block by a transarterial approach is effective and safe in hand surgery.  相似文献   
39.
The purpose was to investigate experienced loneliness among the elderly. The material included 1725 people, aged 75 and over. The study describes relationships between loneliness, social network, cognitive function and health. Thirty-five per cent experienced loneliness, and a higher percentage was found among women. A gradual increase in loneliness was found up to the age of 90, after which a levelling was found. Elderly persons living together with a partner experienced less loneliness. There were no significant differences between those with and without children. Ten per cent reported not having any friends and, of these, one out of two experienced loneliness. A high frequency of experienced loneliness was found among elderly people with reduced cognitive function. Subjectively experienced bad health and loneliness were strongly related to each other, i.e. a person who experienced loneliness did usually not feel completely healthy.  相似文献   
40.
H O Svensson  G B Andersson 《Spine》1989,14(5):517-522
The association between low-back pain (LBP) and different work factors was investigated in a retrospective cross-sectional study of a random sample of 1,760 38- to 64-year-old women. The life-time incidence of LBP was 66% and the prevalence was 35%. In a univariate analysis, eight work variables correlated to LBP viz. more forward bending, more lifting, more standing, more monotonous work, dissatisfaction with the work tasks, dissatisfaction with the work environment, a higher degree of worry, and fatigue at the end of the work day. In a covariate analysis, however, only the three psychological variables remained directly associated to LBP viz. dissatisfaction with the work environment, a higher degree of worry, and fatigue at the end of the work day.  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