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   2191篇
  免费   142篇
  国内免费   66篇
耳鼻咽喉   36篇
儿科学   94篇
妇产科学   47篇
基础医学   191篇
口腔科学   50篇
临床医学   242篇
内科学   501篇
皮肤病学   100篇
神经病学   79篇
特种医学   277篇
外科学   176篇
综合类   62篇
一般理论   1篇
预防医学   287篇
眼科学   24篇
药学   101篇
肿瘤学   131篇
  2021年   22篇
  2020年   19篇
  2019年   11篇
  2018年   19篇
  2017年   17篇
  2016年   20篇
  2015年   32篇
  2014年   34篇
  2013年   53篇
  2012年   65篇
  2011年   75篇
  2010年   51篇
  2009年   86篇
  2008年   104篇
  2007年   132篇
  2006年   102篇
  2005年   84篇
  2004年   93篇
  2003年   62篇
  2002年   67篇
  2001年   79篇
  2000年   56篇
  1999年   52篇
  1998年   76篇
  1997年   78篇
  1996年   81篇
  1995年   65篇
  1994年   52篇
  1993年   70篇
  1992年   35篇
  1991年   42篇
  1990年   49篇
  1989年   56篇
  1988年   36篇
  1987年   53篇
  1986年   29篇
  1985年   42篇
  1984年   40篇
  1983年   33篇
  1982年   28篇
  1981年   33篇
  1980年   27篇
  1979年   11篇
  1978年   17篇
  1977年   13篇
  1976年   8篇
  1975年   13篇
  1973年   9篇
  1969年   6篇
  1968年   7篇
排序方式: 共有2399条查询结果,搜索用时 31 毫秒
31.
32.
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   
33.
34.
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   
35.
36.
OBJECTIVES: To assess whether different definitions of acute coronary events yielded concordant results concerning trends and geographical disparities in coronary heart disease (CHD) mortality and morbidity in France. STUDY DESIGN: Data from three French CHD registries participating in the WHO MONICA Project during the period 1985-1992. SETTING: Three areas of about one million inhabitants each in the North, South and East of France. SUBJECTS: About 2,000 acute coronary events each year. MAIN OUTCOME MEASURES: Mortality, annual rate of fatal and non-fatal events, incidence of first and recurrent events, case-fatality rates. RESULTS: For incidence and mortality, the broader the broader the definition of the acute event, the higher the reported rates. The same tendency was not observed for case-fatality rates. Comparing between-registry rates for mortality, 28-day case-fatality and hospital case fatality yielded relatively concordant results whatever the definition of event. As a whole, the higher mortality rate in Lille and its intermediate rank in Strasbourg were related more to disparities in case-fatality rates, with only small variations in incidence rates, independently of the definition used. Comparing temporal trends in rates within and between regions, a consistent decrease in annual mortality rates and case-fatality rates was observed, whatever the definition. In contrast, the incidence of non-fatal probable myocardial infarction did not change during the period in any register. CONCLUSIONS: Although the absolute estimates of rates were variable with the definition of the event, major findings in relation to trends and geographical disparities were fairly consistent across the definitions: the North-South gradient in mortality observed in France was found to be much more pronounced for case fatality than for incidence. The proportion of milder acute myocardial infarction is currently increasing and this element should be taken into account when analysing CHD rates.  相似文献   
37.
Long-chain 3-hydroxyacyl-coenzyme A dehydrogenase (LCHAD), the third enzyme of the mitochondrial -oxidation pathway, carries out the dehydrogenation of 3-hydroxyacyl-CoA compounds of 12–18 carbon length. To date only nine cases of LCHAD deficiency have been documented. We report a further patient who as a neonate developed non-specific gastro-intestinal symptoms and at 5 months of age cardiomyopathy, recurrent hypoketotic hypoglycaemia and gross alterations of plasma carnitine fractions. Dietary management with medium chain triglycerides led rapidly to clinical improvement. There was a close correlation between the clinical condition, plasma carnitine fractions and cardiac function. At 2 years of age she is developing normally.  相似文献   
38.
This is the first study to test concurrently the effectiveness of four treatment programs for patients with serious mental illness. Three-year outcome data on utilization and functioning demonstrated important positive changes for seriously mentally ill veterans enrolled in specialized, enhanced inpatient and community case management treatment programs, when compared to patients in an enhanced day treatment program or traditional standard care.  相似文献   
39.
Objective: To evaluate the incidence and severity of apnoea and bradycardia in hospitalized preterm infants following immunization at 2 months of age, and identify risk factors.
Methodology: A prospective study of 98 preterm infants, of gestational age 24–31 weeks, immunized at approximately 2 months post natal age with diphtheria-tetanus-whole cell pertussis vaccine (DTPw) in the neonatal intensive care unit (NICU) at King George V Hospital Sydney. Half the infants also received Haemophilus influenzae type b conjugate vaccine (Hib) simultaneously. All infants were monitored for apnoea and bradycardia in the 24 h periods pre- and post immunization.
Results: Only one infant had apnoea and/or bradycardia pre-immunization compared with 17 post immunization. For 12 infants these events were brief, self-limiting and not associated with desaturations (oxygen saturation <90%). However, for five infants (30%) these events were associated with oxygen desaturation and two of these infants required supplemental oxygen. The group that had apnoea and/or bradycardia and the group that did not were not significantly different in terms of gestational age, birth weight and other variables. Infants who received Hib together with DTPw were less likely to have apnoea and/or bradycardia than those given DTPw alone.
Conclusion: When considering immunization for preterm infants, the benefits of early immunization must be balanced against the risk of apnoea and bradycardia. We recommend that the cardio-respiratory function of hospitalized infants born at less than 31 weeks gestation be monitored for 48 h post immunization.  相似文献   
40.
A diet history method for estimating energy and N intakes was validated against 24 h urinary N excretion and energy expenditure measured by the doubly-labelled water (DLW) method. Forty-eight women aged 50-65 years were studied over 1 year. Weighed diet records from 4 d and two 24 h urine collections, for measurement of urinary N excretion, were obtained in each of four seasons. At the end of the year, a diet history was obtained, BMR was measured by whole-body calorimetry, and, in sixteen women, total energy expenditure (EE) was measured by DLW. Energy intake (EI) and N intake (NI) were calculated using food tables. Using weighed records and diet history respectively mean NI were 11.21 (SD 2.09) g and 11.47 (SD 2.40) g (NS) and EI were 8.08 (SD 1.54) MJ and 8.20 (SD 1.86) MJ (NS). Mean urine N:NI and EI:BMR values indicated bias to under-reporting by weighed record and diet history techniques in some individuals, but there was no significant difference between these measures at the group level. The Pearson correlation coefficient (r) for urine N v. NI was 0.81 for the weighed record and 0.38 for the diet history. The correlation of EE v. EI was r 0.48 for weighed record and r 0.11 for diet history. In this study the diet history gave the same estimate of mean intake, but the weighed record appeared to perform better in ranking individuals.  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