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   4794篇
  免费   249篇
  国内免费   77篇
耳鼻咽喉   23篇
儿科学   125篇
妇产科学   205篇
基础医学   593篇
口腔科学   64篇
临床医学   480篇
内科学   1036篇
皮肤病学   62篇
神经病学   264篇
特种医学   433篇
外国民族医学   1篇
外科学   634篇
综合类   49篇
一般理论   2篇
预防医学   321篇
眼科学   44篇
药学   350篇
中国医学   4篇
肿瘤学   430篇
  2021年   42篇
  2020年   36篇
  2019年   50篇
  2018年   57篇
  2017年   51篇
  2016年   65篇
  2015年   85篇
  2014年   103篇
  2013年   116篇
  2012年   187篇
  2011年   204篇
  2010年   145篇
  2009年   132篇
  2008年   149篇
  2007年   211篇
  2006年   152篇
  2005年   206篇
  2004年   178篇
  2003年   173篇
  2002年   155篇
  2001年   159篇
  2000年   153篇
  1999年   117篇
  1998年   131篇
  1997年   109篇
  1996年   101篇
  1995年   95篇
  1994年   72篇
  1993年   77篇
  1992年   114篇
  1991年   93篇
  1990年   104篇
  1989年   120篇
  1988年   118篇
  1987年   96篇
  1986年   84篇
  1985年   101篇
  1984年   52篇
  1983年   43篇
  1982年   43篇
  1981年   34篇
  1980年   31篇
  1979年   38篇
  1978年   38篇
  1977年   47篇
  1976年   32篇
  1975年   42篇
  1973年   46篇
  1972年   29篇
  1966年   28篇
排序方式: 共有5120条查询结果,搜索用时 0 毫秒
61.
Since the development of coronary heart disease (CAD) is affected by a specific pattern of plasma high density lipoprotein (HDL) effects it may be useful to know whether this occurs already in childhood. In this study we evaluated particle size distribution of HDL by gradient gel electrophoresis and the determination of cholesterol esterification rate (FERHDL) in plasma depleted of apo B lipoproteins in 221 children (108 boys and 113 girls) aged 4 months to 20 years. Total plasma- (TC), low-density lipoprotein- (LDL-C) and HDL- (HDL-C) cholesterol, HDL unesterified cholesterol (HDL-UC) and plasma triglycerides (TG) were also measured. There were no significant gender and age differences with respect to the plasma TC, LDL-TC and TG but concentration of HDL-TC increased with age. Post-pubertal girls had significantly higher relative concentrations of HDL2b compared to boys (30.4% vs 17.2%), while HDL3b,c was lower in post-pubertal girls (8.7% vs. 16.5 %). FERHDL correlated inversely with HDL2b and positively with HDL3b,c particles and was significantly higher in boys of the post-pubertal group compared to girls (16.9%/h vs 12.5%/h). While in girls there was a positive correlation between age and HDL-C, HDL-UC and the relative concentration of HDL2b no significant correlation were observed in boys. In girls the increase in TC showed a significant correlation with a simultaneous increase in HDL-C, HDL-UC and HDL2b. In boys TC correlated significantly with changes in TG only. When HDL2b and HDL3b,c cholesterol levels are calculated from HDL-C concentration and per cent distribution the differences between males and females are further emphasized. These data indicate that HDL particle size distribution is age- and gender-dependent.  相似文献   
62.
Persistent hyperinsulinemic hypoglycaemia of infancy (PHHI) is the most frequent cause of hypoglycaemia in infancy. Clinical presentation is heterogeneous, with variable onset of hypoglycaemia and response to diazoxide, and presence of sporadic or familial forms. Underlying histopathological lesions can be focal or diffuse. Focal lesions are characterised by focal hyperplasia of pancreatic islet-like cells, whereas diffuse lesions implicate the whole pancreas. The distinction between the two forms is important because surgical treatment and genetic counselling are radically different. Focal lesions correspond to somatic defects which are totally cured by limited pancreatic resection, whereas diffuse lesions require a subtotal pancreatectomy exposing to high risk of diabetes mellitus. Diffuse lesions are due to functional abnormalities involving several genes and different transmission forms. Recessively inherited PHHI have been attributed to homozygote mutations for the beta-cell sulfonylurea receptor (SUR1) or the inward-rectifying potassium-channel (Kir6.2) genes. Dominantly inherited PHHI can implicate the glucokinase gene, particularly when PHHI is associated with diabetes, the glutamate dehydrogenase gene when hyperammonaemia is associated, or another locus.  相似文献   
63.
The measurement of regional cerebral blood flow (rCBF) and perfusion reserve (PR) with H2(15)O positron emission tomography (PET) and acetazolamide challenge is of importance in evaluating patients with cerebrovascular disease and is thought to be useful in selecting patients for possible vascular surgery. Full quantitative assessment of rCBF with PET requires arterial blood sampling, which is inconvenient in a clinical setting. In this work, we present a simple non-invasive method with which to quantitatively evaluate PR in one PET session lasting no more than 30 min. In ten patients with cerebrovascular disease, rCBF was measured with H2(15)O PET under the baseline condition and after administration of 1 g acetazolamide using a standard technique involving arterial blood sampling. The activity accumulated over 60 s was normalized to injected activity per kilogram body weight (nAA) and compared with rCBF in eight different brain regions. A high linear correlation was found for PR based on nAA (PRnAA) and rCBF (PRrCBF) (PRnAA=0.843 PRrCBF + 0.092, r=-0.83, Pearson's correlation coefficient). Bland-Altman analyses further confirmed that PRnAA reflects PR in a quantitative manner. These results demonstrate that the method based on normalized counts allows the quantitative assessment of PR without blood sampling.  相似文献   
64.
PURPOSE: Although rare overall, marginal zone B-cell lymphoma (MZBCL) is the most common primary low-grade CNS lymphoma reported in the literature. The aim of this study is to elucidate the biology and genetic features of this unusual tumor. PATIENTS AND METHODS: Fifteen CNS MZBCLs were studied clinically, pathologically, and genetically, including fluorescent in situ hybridization analyses with commercially available MALT1 and IgH break-apart and centromere 3, 7, 12, and 18 probes. RESULTS: CNS MZBCLs preferentially affect middle-aged women (female-to-male ratio, 4:1), with 93% presenting as dural-based masses mimicking meningioma. Ten patients with 1 to 7.6 years of follow-up after diagnosis showed no evidence of disease after radiation and/or chemotherapy. Like MZBCLs outside of the CNS, they consisted of CD20+, CD3- small B lymphocytes with varying degrees of plasmacytic differentiation and predominantly kappa light-chain restriction (78%). Lymphoid follicles with follicular colonization were seen in three patients and deposition of amyloid was noted in samples from two patients, one of which was tumefactive. Neither Bcl-6 protein nor Epstein-Barr virus-encoded RNA was expressed. Trisomy 3 was detected in six of 12 patients, with no rearrangements of MALT1 or IgH and no trisomies of 7, 12, or 18 detected. CONCLUSION: Our data suggest that intracranial MZBCL is an indolent primary CNS lymphoma that typically presents as a meningioma-like dural-based mass. Trisomy 3, but not MALT1 or IgH translocation, is a common genetic abnormality that may contribute to the pathogenesis of this CNS lymphoma.  相似文献   
65.
The Mediterranean diet (MD) is known to be one of the healthiest dietary patterns. Despite the significance of a healthful diet during the early stage of life, data for young individuals indicate that nutrition problems are common. This cross-sectional study aimed to determine parental factors associated with MD adherence in children and adolescents living in the Mediterranean region in Croatia. In total, 2623 children aged 2 to 18 years and their parents participated in this study. Data were collected during the period from September 2021 to February 2022 by using an anonymous questionnaire. We used KIDMED and MEDAS questionnaires for assessing MD adherence in young individuals and their parents, respectively. To assess the association of children’s MD adherence categories with the parental predictors, we performed multivariate multinomial logistic regression. Results showed that the children of parents with a low MD adherence are much more likely to have poor MD adherence than good (OR = 47.54 (95% C.I 18.24, 123.87), p < 0.001) or average (OR = 5.64 (95% C.I 3.70, 8.6), p < 0.001) MD adherence. Further, children of fathers with higher BMI (OR = 1.035 (95% C.I 1.0, 1.071)) and those who do not live with both parents (OR = 1.703 (95% C.I 0.994, 2.916), p = 0.053) are more likely to have poor MD adherence than good MD adherence. These results indicate that interventions focusing on enhancing the quality of both parents’ diets could effectively improve their children’s eating habits.  相似文献   
66.
67.
Elevated office blood pressure (BP) has previously been associated with increased levels of circulating extracellular vesicles (EVs). The present study aimed to assess the relationship between levels of platelet derived EVs, ambulatory BP parameters, and pulse wave velocity as a marker of macrovascular organ damage. A total of 96 participants were included in the study. Platelet‐derived extracellular vesicles (pEVs) were evaluated by flow cytometry (CD41+/Annexin v+). BP evaluation included unobserved automated office BP and ambulatory BP monitoring. Carotid‐femoral pulse wave velocity (PWV) was measured as a marker of macrovascular damage. pEVs correlated with nocturnal systolic BP (r = 0.31; p = .003) and nocturnal dipping (r = ‐0.29; p = .01) in univariable analysis. Multivariable regression models confirmed robustness of the association of EVs and nocturnal blood pressure (p = .02). In contrast, systolic office, 24h‐ and daytime‐BP did not show significant associations with pEVs. No correlations were found with diastolic BP. Circulating pEVs correlated with pulse wave velocity (r = 0.25; p = .02). When comparing different hypertensive phenotypes, higher levels of EVs and PWV were evident in patients with sustained hypertension compared to patients with white coat HTN and healthy persons. Circulating platelet derived EVs were associated with nocturnal BP, dipping, and PWV. Given that average nocturnal BP is the strongest predictor of CV events, platelet derived EVs may serve as an integrative marker of vascular health, a proposition that requires testing in prospective clinical trials.  相似文献   
68.
MMPI and 16 PF patterns of a group of drug abusers who were participating in a voluntary VA Drug Abuse Program were investigated. The MMPI profiles of 91 male veterans who ranged in age from 18-45 years were classified according to two-point code types. A comparison was made of the most frequently occurring code types among drug abusers, medical patients, and psychiatric patients. The two modal profile types among drug abusers were the 4-9/9-4 and the 2-4/4-2, which accounted for 32% of the sample. An additional comparison between the two modal types and responses to the 16 PF was made. Results indicate a closer resemblance to psychiatric patients than to medical patients, and the variety of high point code types is discussed. The similarity between the present sample of modal code types with research on drug abusers undertaken 20 years previously also is discussed.  相似文献   
69.
A 46-year-old man ingested approximately 50 ml of a plastic resin catalyst He developed persistent gastrointestinal bleeding, renal and hepatic failure, pneumonitis, and septicemia, and died four weeks later. Autopsy revealed chronic esophagitis and gastritis with massive intraluminal gastrointestinal hemorrhage. This case emphasizes the potential danger of ingestion of such substances.  相似文献   
70.
This retrospective, cost consequence analysis examined three distinct outreach strategies used by a community-based public health agency to enroll uninsured, low-income pregnant women in perinatal health care services. The three strategies included outreach workers, liaison workers, and case managers. Data analysis revealed that costs per enrollee by strategy were: outreach workers: $429; liaison workers: $98; and case managers: $187. Cost per strategy must be considered cautiously, however, because outreach and enrollment strategies at this agency are not mutually exclusive. Data analysis also revealed that the number of low and very low birth weight babies born to women enrolled in the study agency was half that of the general population, even though less than half the participants were enrolled in prenatal care during the first trimester of pregnancy. Findings from this study support the use of outreach and enrollment strategies to reduce barriers to access to health care and reduce health disparities of low-income, vulnerable populations.  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