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   1381篇
  免费   101篇
  国内免费   24篇
耳鼻咽喉   16篇
儿科学   48篇
妇产科学   13篇
基础医学   147篇
口腔科学   15篇
临床医学   157篇
内科学   231篇
皮肤病学   67篇
神经病学   91篇
特种医学   198篇
外科学   158篇
综合类   21篇
一般理论   1篇
预防医学   125篇
眼科学   20篇
药学   106篇
肿瘤学   92篇
  2021年   17篇
  2020年   13篇
  2019年   15篇
  2018年   20篇
  2017年   14篇
  2016年   14篇
  2015年   10篇
  2014年   36篇
  2013年   43篇
  2012年   49篇
  2011年   43篇
  2010年   36篇
  2009年   31篇
  2008年   44篇
  2007年   52篇
  2006年   49篇
  2005年   83篇
  2004年   48篇
  2003年   43篇
  2002年   40篇
  2001年   33篇
  2000年   42篇
  1999年   33篇
  1998年   40篇
  1997年   33篇
  1996年   43篇
  1995年   30篇
  1994年   24篇
  1993年   36篇
  1992年   29篇
  1991年   21篇
  1990年   22篇
  1989年   35篇
  1988年   36篇
  1987年   46篇
  1986年   26篇
  1985年   32篇
  1984年   25篇
  1983年   31篇
  1982年   31篇
  1981年   19篇
  1980年   18篇
  1979年   16篇
  1978年   11篇
  1977年   16篇
  1976年   20篇
  1975年   14篇
  1973年   6篇
  1972年   4篇
  1967年   4篇
排序方式: 共有1506条查询结果,搜索用时 15 毫秒
11.
The results of the measurement of vitamin B(12) absorption by counting the radioactivity of 5 ml. serum obtained eight to 10 hours after the ingestion of an oral dose of 0.5 mug. vitamin B(12) labelled with 0.5 muc. (57)Co are compared with those obtained with the urinary excretion (Schilling) test. Inadequate urine collection and impaired renal function were responsible for low results in the Schilling test in four of the 12 control subjects, and an incomplete urine collection in four patients with pernicious anaemia could have led to doubt about the validity of the low result.The measurement of serum radioactivity for 1,000 seconds gave conclusive results, the range in the patients with malabsorption of vitamin B(12) being between 0 and 24 counts per minute, and in the control subjects and other patients with megaloblastic anaemia between 28 and 64 counts per minute. The highest serum radioactivity level in a patient with pernicious anaemia was 19 counts per minute.Serum counting is simpler than the Schilling test and may be done alone when the patient's renal function is known to be poor, when urine collection is expected to be unreliable, or when the flushing dose of vitamin B(12) should be avoided. Otherwise there is an advantage in doing both tests together for confirmation.  相似文献   
12.
Oligonucleotide fingerprinting of genomic DNA from oral isolates of four different Candida species other than C. albicans and atypical chlamydospore-positive isolates from human immunodeficiency virus (HIV)-positive individuals and AIDS patients was investigated as a means for differentiating between isolates within individual species. Oligonucleotides composed of simple repetitive sequence motifs, including (GACA)4, (GATA)4, (GGAT)4, (GTG)5, and (GT)8, all yielded fingerprints suitable for strain segregation of 8 C. tropicalis isolates, 12 Torulopsis (Candida) glabrata isolates, 8 atypical Candida isolates, and, except for (GATA)4, 2 C. krusei probe in turn and so generate several distinct DNA fingerprints of the same DNA sample. However, none of the probes yielded fingerprints suitable for strain segregation with three C. parapsilosis isolates. The (GATA)4 probe was also used to detect restriction fragment length polymorphisms among a genetically closely related group of atypical Candida isolates on primary isolation from an additional HIV-infected patient. These chlamydospore-positive atypical Candida isolates were sucrose positive, were of C. albicans serotype A, hybridized weakly with the C. albicans-specific mid-repeat sequence probe 27A, and yielded fingerprint profiles by random polymorphic DNA analysis that were distinct from those derived from C. albicans isolates. The C. stellatoidea ex-type strain NCPF 3108 was indistinguishable from the atypical Candida isolates in all these tests and also yielded an identical carbohydrate and nitrogen source assimilation profile by using the ID 32C yeast identification system.  相似文献   
13.
Ultrasound scans of 51 consecutive patients with gallbladder wall thickening were reviewed, and specific sonographic features were correlated with surgical and clinical follow-up. Two patterns of thickening were identified as specific indicators of the presence or absence of acute cholecystitis. "Striated" wall thickening, consisting of several alternating, irregular, discontinuous, lucent and echogenic bands, was seen in eight of 13 patients (62%) with acute cholecystitis. This pattern was not encountered in any of the patients who did not have acute cholecystitis. Conversely, "three-layer" thickening, consisting of a single circumferential lucent zone between two relatively uniform echogenic layers, was seen in only one of 13 patients (8%) with acute cholecystitis but in 11 of 38 patients (29%) with other diagnoses. Other abnormalities, including the presence of intramural echogenic foci and wall irregularities, were more frequently seen in patients with acute cholecystitis but were not as helpful. Use of these features may suggest or help exclude a diagnosis of acute cholecystitis in those patients in whom the cause of gallbladder wall thickening is otherwise not apparent.  相似文献   
14.
We describe trends in acute rheumatic fever (ARF), rheumatic heart disease (RHD), and RHD deaths among population groups in New Zealand. We analyzed initial primary ARF and RHD hospitalizations during 2000–2018 and RHD mortality rates during 2000–2016. We found elevated rates of initial ARF hospitalizations for persons of Māori (adjusted rate ratio [aRR] 11.8, 95% CI 10.0–14.0) and Pacific Islander (aRR 23.6, 95% CI 19.9–27.9) ethnicity compared with persons of European/other ethnicity. We also noted higher rates of initial RHD hospitalization for Māori (aRR 3.2, 95% CI 2.9–3.5) and Pacific Islander (aRR 4.6, 95% CI 4.2–5.1) groups and RHD deaths among these groups (Māori aRR 12.3, 95% CI 10.3–14.6, and Pacific Islanders aRR 11.2, 95% CI 9.1–13.8). Rates also were higher in socioeconomically disadvantaged neighborhoods. To curb high rates of ARF and RHD, New Zealand must address increasing social and ethnic inequalities.  相似文献   
15.
Organ transplant recipients (OTRs) are at increased risk of cutaneous malignancy. Skin disorders in OTRs of color (OTRoC) have rarely been systematically assessed. We aimed to ascertain the burden of skin disease encountered in OTRoC by prospectively collecting data from OTRs attending 2 posttransplant skin surveillance clinics: 1 in London, UK and 1 in Philadelphia, USA. Retrospective review of all dermatological diagnoses was performed. Data from 1766 OTRs were analyzed: 1024 (58%) white, 376 (21%) black, 261 (15%) Asian, 57 (3%) Middle Eastern/Mediterranean (ME/M), and 48 (2.7%) Hispanic; and 1128 (64%) male. Viral infections affected 45.1% of OTRs, and were more common in white and ME/M patients (P < .001). Fungal infections affected 28.1% and were more common in ME/M patients (P < .001). Inflammatory skin disease affected 24.5%, and was most common in black patients (P < .001). In addition, 26.4% of patients developed skin cancer. There was an increased risk of skin cancer in white vs nonwhite OTRs (HR 4.4, 95% CI 3.5-5.7, P < .001): keratinocyte cancers were more common in white OTRs (P < .001) and Kaposi sarcoma was more common in black OTRs (P < .001). These data support the need for programs that promote targeted dermatology surveillance for all OTRs, regardless of race/ethnicity or country of origin.  相似文献   
16.
Comrades     
Four organisations have collaborated to produce a consensus statement on clinical management. The result, writes Alys Harwood, could lead to a revolution in patient care.  相似文献   
17.
18.
OBJECTIVE--To develop a handicap measurement scale in a self completion questionnaire format, with scale weights allowing quantification of handicap at an interval level of measurement. DESIGN--Adaptation of the International Classification of Impairments, Disabilities and handicaps into a practical questionnaire incorporating the dimensions of handicap mobility, occupation, physical independence, social integration, orientation, and economic self sufficiency and scale weights derived from interviews with a general population sample, with the technique of conjoint analysis. SETTING--Two general practices in different areas of London. SUBJECTS--240 adults aged 55-74 years randomly selected from the practices, 101 (42%) of whom agreed to be interviewed, and 79 (78%) of whom completed the exercise. MAIN MEASURES--Rating of severity of handicap associated with 30 hypothetical health scenarios on a visual analogue scale, from which was derived a matrix of scale weights ("part utilities") relating to different levels of disadvantage on each dimension, with a formula for combining them into an overall handicap score. Severity scores measured directly for five scenarios not used to derive the scale weights were compared with those calculated from the formula to validate the model. RESULTS--The part utilities obtained conformed with the expected hierarchy for each dimension, confirming the validity of the method. The measured severities and those calculated from the formula for the five scenarios used to validate the model agreed closely (Pearson's r = 0.98, p = 0.0009; Kendall's tau = 1.00, p = 0.007). CONCLUSIONS--This interval level handicap measurement scale will be useful in assessing both specific therapies and health services, in clinical trials, in analyses of cost effectiveness, and in assessments of quality assurance.  相似文献   
19.
OBJECTIVE: To determine whether elderly medical inpatients without dementia who score >3.31 on the short form of the Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE) are at an increased risk of developing dementia.DESIGN/PARTICIPANTS: Twenty-nine patients with an IQCODE score of >3.31 without dementia and 29 age- and sex-matched controls, from an original sample of 201 medical inpatients over 65, were examined 17-24 months after initial assessment.SETTING: Interviews took place in patients' homes, but all subjects had been recruited while medical inpatients in a general hospital 17-24 months previously.MEASURES: The IQCODE and clinical interview to make DSM-III-R diagnosis of dementia.RESULTS: Ten of the study group and one control had developed dementia since the original assessment.CONCLUSIONS: Non-demented elderly medical inpatients with an admission IQCODE score of >3.31 are more likely to develop dementia than those with an IQCODE score of <3.31. The IQCODE is a sensitive tool for detecting early dementia.  相似文献   
20.
A large number of studies have examined both the epidemiology and neuropsychiatric manifestations of dementia among older adults. However, there is a relative dearth of studies focusing on ethnic minority elders in the United States. This article reviews the existing empiric literature in the area of ethnicity and dementia. For the purpose of this paper, the focus will be on Hispanics and black Americans, the two most prevalent ethnic minority populations in the United States. This review includes discussion of terminology issues, diagnosis, epidemiology, and clinical features, in addition to caregiver issues.  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