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   3537篇
  免费   229篇
  国内免费   76篇
耳鼻咽喉   49篇
儿科学   271篇
妇产科学   101篇
基础医学   509篇
口腔科学   59篇
临床医学   388篇
内科学   858篇
皮肤病学   29篇
神经病学   273篇
特种医学   319篇
外国民族医学   1篇
外科学   364篇
综合类   85篇
一般理论   2篇
预防医学   161篇
眼科学   113篇
药学   125篇
中国医学   2篇
肿瘤学   133篇
  2021年   31篇
  2019年   30篇
  2018年   41篇
  2017年   31篇
  2016年   35篇
  2015年   46篇
  2014年   55篇
  2013年   88篇
  2012年   122篇
  2011年   123篇
  2010年   94篇
  2009年   80篇
  2008年   94篇
  2007年   153篇
  2006年   112篇
  2005年   98篇
  2004年   109篇
  2003年   97篇
  2002年   84篇
  2001年   104篇
  2000年   120篇
  1999年   103篇
  1998年   91篇
  1997年   96篇
  1996年   94篇
  1995年   83篇
  1994年   67篇
  1993年   71篇
  1992年   91篇
  1991年   101篇
  1990年   69篇
  1989年   99篇
  1988年   83篇
  1987年   97篇
  1986年   76篇
  1985年   78篇
  1984年   51篇
  1983年   65篇
  1982年   40篇
  1981年   45篇
  1980年   41篇
  1979年   38篇
  1978年   31篇
  1977年   42篇
  1976年   23篇
  1974年   24篇
  1971年   22篇
  1926年   23篇
  1925年   28篇
  1924年   22篇
排序方式: 共有3842条查询结果,搜索用时 15 毫秒
51.
52.
Arterial stenosis is known to be one of the most serious cardiovascular diseases. Angiographical estimation of arterial stenosis provides limited information on the severity of the occlusion and the flow of blood through it. Hemodynamical assessment of the flow and pressure behaviour, is known to be clinically important. Hemodynamically based parameters, such as pressure based myocardial fractional flow reserve (FFR) and the flow based coronary flow reserved (CFR) were introduced to provide a much better tool for treating arterial diseases.We have developed a new method for simultaneous measurement of pressure-derived CFR and FFR. The advantage of pressure derived hemodynamic parameters is very substantial, and its relatively straightforward application in clinical setting is solid. The method has been validated by means of a computational fluid dynamics (CFD) model of the arterial stenosis and in vitro bench studies.  相似文献   
53.
54.
Lung carcinoids occur sporadically and rarely in association with multiple endocrine neoplasia type 1 (MEN1). There are no well defined genetic abnormalities known to occur in these tumors. We studied 11 sporadic lung carcinoids for loss of heterozygosity (LOH) at the locus of the MEN1 gene on chromosome 11q13, and for mutations of the MEN1 gene using dideoxy fingerprinting. Additionally, a lung carcinoid from a MEN1 patient was studied. In four of 11 (36%) sporadic tumors, both copies of the MEN1 gene were inactivated. All four tumors showed the presence of a MEN1 gene mutation and loss of the other allele. Observed mutations included a 1 bp insertion, a 1 bp deletion, a 13 bp deletion and a single nucleotide substitution affecting a donor splice site. Each mutation predicts truncation or potentially complete loss of menin. The remaining seven tumors showed neither the presence of a MEN1 gene mutation nor 11q13 LOH. The tumor from the MEN1 patient showed LOH at chromosome 11q13 and a complex germline MEN1 gene mutation. The data implicate the MEN1 gene in the pathogenesis of sporadic lung carcinoids, representing the first defined genetic alteration in these tumors.   相似文献   
55.
Empirical evidence suggests that mortality rates for coronary artery bypass graft (CABG) surgery are lower in hospitals that perform a higher volume of the procedure. In recent years, the criteria for CABG surgery have been expanded to include patients with a wide variety of co-morbidities. To address the question of whether the volume-outcome relationship continues to exist for this new group of patients, discharge abstracts for 18,986 CABG operations at 77 hospitals in California in 1983 were analyzed using multiple-regression techniques. Higher-volume hospitals had lower in-hospital mortality (adjusted for case mix); this effect was greatest in patients who might be characterized as having "non-scheduled" CABG surgery. Higher-volume hospitals also had shorter average postoperative lengths of stay and fewer patients with extremely long stays. The results of this study suggest that the greatest improvement in average outcomes for CABG surgery would result from the closure of low-volume surgery units.  相似文献   
56.
57.
Highly effective CFTR modulator drug therapy is increasingly available to those with cystic fibrosis. Multiple observational research studies are now being conducted to better understand the impacts of this important therapeutic milestone on long-term outcomes, patient care needs, and future research priorities. PROMISE is a large, multi-disciplinary academic study focused on the broad impacts of starting elexacaftor/tezacaftor/ivacaftor in the US population age 6 years and older. The many areas of investigation and rationale for each are discussed by organ systems, along with recognition of remaining important questions that will not be addressed by this study alone. Knowledge gained through this and multiple complementary studies around the world will help to understand important health outcomes, clinical care priorities, and research needs for a large majority of people treated with these or similarly effective medications targeting the primary cellular impairment in cystic fibrosis.  相似文献   
58.
止泻散敷脐治疗婴幼儿腹泻100例   总被引:1,自引:1,他引:0  
梁蜀筠  刘延英 《医学争鸣》2000,21(12):1500-1500
0 引言 腹泻乃小儿最常见病 ,尤以 2岁以下婴幼儿最为常见 .年龄越小 ,发病率越高 ,且多在夏、秋季发病 .小儿患病后惧怕打针 ,服药以及输液 ,给治疗带来一些困难 . 12 a来 ,我们用自拟的止泻散敷脐治疗婴幼儿泄泻 ,效果良好 .1 对象和方法1.1 对象  1998- 0 6 / 1999- 10婴幼儿腹泻发病高峰期门诊病例 10 0 (男 6 6 ,女 34 )例 ,年龄 2月龄~ 5岁 .肠炎 5 8例 ,单纯消化不良 42例 . 6 7例曾多次治疗 ,33例初诊 .凡接受治疗之患儿 ,一律停止用其他药物 .1.2 方法 药物组成 :川椒 12 g,干姜 12 g,小茴香 12 g,白芷 2 0 g,吴茱萸 5 g,…  相似文献   
59.
SUMMARY  Previous studies have shown that premature infants may be at risk for hypoxemia and bradycardia when placed in standard car seats. However, the relationship of such breathing abnormalities to sleep state have not been studied. The purpose of the present study was to investigate the effect of car seat positioning on respiratory patterns in preterm infants during sleep and to evaluate their relationship to sleep state. Complete polysomnography, including sleep and breathing parameters, was performed on twenty-eight premature infants. Each infant was randomly assigned to the car seat or prone (crib) position for the first recording period. Following the recording of at least two sleep cycles, the position was reversed. The percentage of active and quiet sleep was calculated and breathing parameters were measured. In the car seat, the infants spent significantly more time in active sleep and less time in quiet sleep than in the prone position, of the respiratory parameters, periodic breathing (PB) was significantly higher in the car seat. The presence of at least one abnormal breathing events (bradycardia, desaturation, PB apnoea) was also significantly higher in the car seat. An analysis of variance (ANOVA) of PB revealed significant sleep-state effect (active vs. quiet sleep), but no significant condition or interaction effects, indicating that PB was more frequent in active sleep regardless of the sleeping condition. It is concluded that increased active sleep in the car seat condition, rather than the positioning of the infant in the seat per se, may account for the increase in periodic breathing and possibly other breathing abnormalities reported in car seats.  相似文献   
60.
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