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   127615篇
  免费   7500篇
  国内免费   722篇
耳鼻咽喉   1175篇
儿科学   4189篇
妇产科学   2945篇
基础医学   18294篇
口腔科学   4192篇
临床医学   12334篇
内科学   28577篇
皮肤病学   3151篇
神经病学   12603篇
特种医学   2839篇
外国民族医学   1篇
外科学   11371篇
综合类   522篇
一般理论   73篇
预防医学   13048篇
眼科学   1953篇
药学   8836篇
中国医学   450篇
肿瘤学   9284篇
  2024年   135篇
  2023年   1222篇
  2022年   2540篇
  2021年   4349篇
  2020年   2747篇
  2019年   3781篇
  2018年   4202篇
  2017年   3181篇
  2016年   3697篇
  2015年   4077篇
  2014年   5317篇
  2013年   6956篇
  2012年   10663篇
  2011年   11034篇
  2010年   5991篇
  2009年   5047篇
  2008年   8755篇
  2007年   8778篇
  2006年   8186篇
  2005年   7611篇
  2004年   6863篇
  2003年   6092篇
  2002年   5485篇
  2001年   662篇
  2000年   457篇
  1999年   731篇
  1998年   964篇
  1997年   771篇
  1996年   669篇
  1995年   567篇
  1994年   505篇
  1993年   431篇
  1992年   329篇
  1991年   238篇
  1990年   230篇
  1989年   223篇
  1988年   209篇
  1987年   169篇
  1986年   192篇
  1985年   142篇
  1984年   175篇
  1983年   153篇
  1982年   178篇
  1981年   141篇
  1980年   142篇
  1979年   82篇
  1978年   95篇
  1977年   82篇
  1976年   83篇
  1974年   62篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
61.
Asthma patients that depend on emergency department (ED) services are generally considered to have extremely poor disease control and prognosis. It is important to identify characteristics related to poor disease control and frequent visits to the ED to apply appropriate clinical management. This study comprised a cross-sectional survey of consecutive patients with asthma exacerbation (age ≥12 years) presenting at the adult ED of a large, tertiary care, university-affiliated hospital over a 2-month period. The frequent visitors (FV) were defined by ≥3 visits to the ED in the preceding year, and the occasional visitors (OV) by ≤2 visits. Eighty-six patients (61 females and 25 males) were included in the study (mean age 38 ± 18 years). Of these patients, 51.2% were FV and 48.8% were OV. Sixty-nine percent had annual income lower than A$3000 and 66.3% had ≤8 years of the formal education. Only 18.6% had used inhaled corticosteroids, 79.1% identified the asthma attack severity, 70.9% increased or initiated inhaled β-agonist, 20.9% increased or initiated steroid therapy, and 55.8% had an asthma action plan for attack. The number of hospital admissions in past year (OR 4.3, P = .02), use of home nebulizer (OR 3.6, P = .05) and the lack of a written asthma action plan (OR 3.3, P = .03) were independently associated with frequent visits to the ED. We conclude that a substantial proportion of the patients that visit the ED are FV. These patients are more likely to have hospital admission in the past year, to use a home nebulizer, and to lack a written asthma action plan. They should be considered the most important target for asthma education.  相似文献   
62.
Alterations in blood glucose levels are known to be involved in electrocardiogram changes. Various types of arrhythmias have been reported. We present here the case of an 81-year-old woman presenting with transient atrial fibrillation while being treated for hypoglycaemia with dextrose infusion, and finally developing a sinus rhythm. The presence of alterations in glucose blood levels should always be considered as a potential cause of transient atrial fibrillation.  相似文献   
63.
64.
Forty-four evaluable patients with intracranial meningiomas were assessed for the expression of the cell-cycle regulator cyclin D1 and of proteins involved in proliferation and apoptosis such as PCNA, MIB-1, p53 and bcl-2. Analyses were carried out by western blot and immunohistochemistry after immediate processing of fresh tumor specimens. By western blot, expression of cyclin D1 significantly correlated with p53 (p=0.02) and with proliferative activity, as assessed by PCNA expression (p=0.0009). By immunohistochemistry, a significant relationship between cyclin D1 and the proliferation marker MIB-1 was confirmed (p=0.05), whereas significance with bcl-2 expression was not found (p=0.01). Moreover, although the association with tumor grade appeared of borderline statistical significance (p=0.07), all the grade II/III meningiomas showed increased expression of cyclin D1 and high proliferative activity. In conclusion, data from this preliminary study seem to suggest a potential value of the combined expression of cyclin D1 and proliferation indicators in defining subgroups of meningiomas with a more aggressive biological behavior.  相似文献   
65.
Atraumetic Restorative Treatment (ART) has been adopted around the world to avoid unnecessary extractions, especially in non-industrialized countries The development of specific glass ionomer cements marketed for the ART technique has contributed to the technical success rate. In this study. Ketac-Molara (3M ESPE. Dental Medzn Germany) was used to restore 150 Class I cavities in 118 Brazilian public school children, aged from 7–12 years. At baseline and at subsequent recalls. CPI probes with a ball-end of 0.5 millimeters (mm) were used to assess loss of restorative material, and photographic color transparencies of restorations were made. After six months. 83 patients returned for follow-up examinations, with 71.8% of their restorations designated as acceptable. After three years. 49 patients with 57 ART-restorations were evaluated, with 21.0% of these restorations graded as acceptable Another 29.8% of their restorations had been replaced by more permanent materials. The main objective of the ART technique is tooth retention; this was achieved for 94.7% of the restored teeth in a high caries risk population who returned for recalls.  相似文献   
66.
We performed a literature search for all clinical studies reporting outcomes in patients with the acquired immunodeficiency syndrome (AIDS) receiving granulocyte-macrophage colony-stimulating factor (GM-CSF) for any indication. Safety outcomes included human immunodeficiency virus replication, immune status, and frequency of opportunistic infections and neoplasms. Data were synthesized qualitatively. We identified 22 studies (274 patients): 12 addressed AIDS neutropenia, 8 AIDS cancer therapy, and 2 opportunistic infections. Viral burden was assessed by serum p24Ag in 15 studies. Nine reported no change in levels, three net decreases, and three net increases. All studies showing net increases involved patients receiving GM-CSF without a concurrent antiretroviral. The CD4 counts were unchanged in 5 studies, increased in 3, and not reported in 14. The incidence of neoplasms or new opportunistic infections was low. The literature suggests no increased risk of viral replication or clinical deterioration in patients with AIDS who take GM-CSF concurrently with zidovudine.  相似文献   
67.
In an attempt to determine the risks for and kinds of dementia most prevalent among the African American population, the Alzheimer's Disease Research Center at the University of Pittsburgh developed a community satellite program specifically targeting the African American and historically medically underserved communities in Allegheny County, PA. The primary mission of the Alzheimer Outreach Center (AOC) was to increase the awareness of AD among the targeted population. The number of nonwhite patients participating in the studies at ADRC increased from 2 to 16% in the first year of the program. In May 1995, the AOC became a permanent ADRC program.  相似文献   
68.
This paper presents the results obtained from 87 questionnaires completed by dietitians about the dietary management of gall-biadder disease. Of the patients referred to the dietitians, 86% were referred by surgeons. Of the dietitians that responded 77% thought that there was a role for low fat diets in the management of these patients; 92% would advise a low fat diet to help avoid pain, and 11% would advise a low fat diet to patients with gall-bladder disease who did not have pain, steatorrhoea or obesity.
The paper reviews the available evidence concerning the effect of dietary fat on the gall-bladder; it is concluded that, at present, there is little data to support the therapeutic use of a low fat diet for individuals with gall-stones.  相似文献   
69.
The neuroendocrine and clinical effects of transdermal 17β-estradiol (rated at 50 μg/day; TTS 50) were studied in 40 postmenopausal women; ten additional postmenopausal women did not receive any drugs. The changes in LH and rectal temperature induced by the infusion of the opioid antagonist naloxone (10 mg i.v. bolus plus 10 mg/h for 4 h) were used to evaluate the central activity of endogenous opioid peptides. TTS 50 increased opioid activity, as evidenced by the restoration of the LH response (P < 0.01) and the enhancement of the hypothermic effect (P < 0.05) of naloxone. A greater reduction in hot flushes was observed in TTS 50-treated subjects than in untreated women, with the maximal effect of TTS 50 achieved after 3 months of therapy. TTS 50 did not modify the concentrations of circulating lipids, glucose or liver enzymes but reduced the biochemical parameters indicative of bone reabsorption. Bone density of the distal radius significantly increased during TTS 50 (P < 0.02), reaching its maximum value after 6 months of therapy. Thereafter bone density declined, but more slowly than in untreated women.

Our data suggest that TTS 50 has marked neuroendocrine effects, that it diminishes the incidence of hot flushes and reduces bone demineralization. By contrast, it has a very little, if any, metabolic impact on the liver or on glucose and lipid metabolism.  相似文献   

70.
We evaluated the effectiveness of statewide bicycle legislation using direct observation of the number of elementary and middle school children riding bicycles with and without helmets to or from school over a 7-year period. The percentage of children wearing helmets increased dramatically over the past 7 years (to a high of 81%) due to the passage of state law that required helmet usage. Rates for elementary school children were consistently higher than rates of middle school children. Numerous children still do not wear helmets, particularly older children. Further interventions are needed to promote helmet wearing.  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