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   3761篇
  免费   419篇
  国内免费   45篇
耳鼻咽喉   29篇
儿科学   118篇
妇产科学   65篇
基础医学   457篇
口腔科学   55篇
临床医学   508篇
内科学   675篇
皮肤病学   73篇
神经病学   407篇
特种医学   222篇
外科学   484篇
综合类   117篇
一般理论   1篇
预防医学   369篇
眼科学   101篇
药学   324篇
中国医学   2篇
肿瘤学   218篇
  2022年   24篇
  2021年   46篇
  2020年   35篇
  2019年   55篇
  2018年   66篇
  2017年   41篇
  2016年   47篇
  2015年   63篇
  2014年   84篇
  2013年   105篇
  2012年   205篇
  2011年   204篇
  2010年   132篇
  2009年   95篇
  2008年   145篇
  2007年   178篇
  2006年   157篇
  2005年   145篇
  2004年   152篇
  2003年   135篇
  2002年   128篇
  2001年   142篇
  2000年   137篇
  1999年   139篇
  1998年   88篇
  1997年   70篇
  1996年   68篇
  1995年   53篇
  1994年   49篇
  1993年   52篇
  1992年   76篇
  1991年   73篇
  1990年   60篇
  1989年   79篇
  1988年   79篇
  1987年   93篇
  1986年   76篇
  1985年   69篇
  1984年   45篇
  1983年   44篇
  1982年   31篇
  1981年   32篇
  1980年   27篇
  1979年   31篇
  1978年   31篇
  1977年   30篇
  1976年   33篇
  1974年   23篇
  1973年   25篇
  1971年   31篇
排序方式: 共有4225条查询结果,搜索用时 15 毫秒
51.
The assessment of causality in drug-event associations depends on the setting and purpose of such an assessment. Epidemiologists are primarily interested in population-based inferences about whether a given drug can cause a certain adverse drug reaction (ADR), and if so, how often it does so. Pharmaceutical industries and regulatory agencies are also concerned with population-based risks, but in addition must worry about individual cases. Clinicians are primarily interested in the individual, ie, whether a given drug did cause a certain adverse event in a particular patient. The authors describe an algorithm that provides specific, detailed criteria for ranking the probability that an observed untoward clinical manifestation was caused by a given drug. The criteria are subdivided into six axes of decision strategy with a built-in scoring system that ordinally ranks the probability of an adverse drug reaction as definite, probable, possible, or unlikely. To illustrate the use of the algorithm, the authors assess a reference case of pancreatitis occurring after administration of methyldopa.  相似文献   
52.
Khadka  J.  Ratcliffe  J.  Hutchinson  C.  Cleland  J.  Mulhern  B.  Lancsar  E.  Milte  R. 《Quality of life research》2022,31(9):2849-2865
Quality of Life Research - To evaluate the construct (convergent and known group) validity of the Quality-of-Life-Aged Care Consumer (QOL-ACC), an older-person-specific quality-of-life measure...  相似文献   
53.
Inactivating mutations in human ecto-nucleotide pyrophosphatase/phosphodiesterase-1 (ENPP1) may result in early-onset osteoporosis (EOOP) in haploinsufficiency and autosomal recessive hypophosphatemic rickets (ARHR2) in homozygous deficiency. ARHR2 patients are frequently treated with phosphate supplementation to ameliorate the rachitic phenotype, but elevating plasma phosphorus concentrations in ARHR2 patients may increase the risk of ectopic calcification without increasing bone mass. To assess the risks and efficacy of conventional ARHR2 therapy, we performed comprehensive evaluations of ARHR2 patients at two academic medical centers and compared their skeletal and renal phenotypes with ENPP1-deficient Enpp1asj/asj mice on an acceleration diet containing high phosphate treated with recombinant murine Enpp1-Fc. ARHR2 patients treated with conventional therapy demonstrated improvements in rickets, but all adults and one adolescent analyzed continued to exhibit low bone mineral density (BMD). In addition, conventional therapy was associated with the development of medullary nephrocalcinosis in half of the treated patients. Similar to Enpp1asj/asj mice on normal chow and to patients with mono- and biallelic ENPP1 mutations, 5-week-old Enpp1asj/asj mice on the high-phosphate diet exhibited lower trabecular bone mass, reduced cortical bone mass, and greater bone fragility. Treating the Enpp1asj/asj mice with recombinant Enpp1-Fc protein between weeks 2 and 5 normalized trabecular bone mass, normalized or improved bone biomechanical properties, and prevented the development of nephrocalcinosis and renal failure. The data suggest that conventional ARHR2 therapy does not address low BMD inherent in ENPP1 deficiency, and that ENPP1 enzyme replacement may be effective for correcting low bone mass in ARHR2 patients without increasing the risk of nephrocalcinosis. © 2021 American Society for Bone and Mineral Research (ASBMR).  相似文献   
54.
Lambert-Eaton myasthenic syndrome is a presynaptic neuromuscular junction disorder typically associated with small cell lung carcinoma. The characterstic electrophysiological abnormality is a low amplitude compound muscle action potential that shows a marked increment after maximal voluntary contraction or brief tetanic nerve stimulation. We describe a patient who had LEMS in association with Hodgkin's disease. A 61 year old woman presented with proximal muscle weakness 6 years following successful treatment of Hodgkin's disease. Her symptoms responded well to treatment with diaminopyridine. 9 additional patients have been described with LEMS in association with lymphoproliferative diseases. A systemic malignancy is usually found within 2 years of LEMS diagnosis but may present later. LEMS should be considered in patients with Hodgkin's disease presenting with muscle weakness.  相似文献   
55.

Poster Session 3

Multiple sclerosis  相似文献   
56.
BACKGROUND: The epidemiologic observation that physical activity reduces the risk for hypertension has only been made for white men who self-reported hypertension. This study examined physical activity and clinically determined incident hypertension in black and white men and women of the Atherosclerosis Risk in Communities (ARIC) Study. METHODS: ARIC is a population-based prospective study with four U.S. clinic centers. The present analyses included 7,459 black and white adults 45-65 years of age. Hypertension (systolic/diastolic blood pressure >/= 140/90 mm Hg) was defined by blood pressure measured by a random-zero device or medication use. Physical activity was assessed with the Baecke questionnaire. RESULTS: After adjustment for age, baseline blood pressure, ARIC center, education, body mass index, waist-hip ratio, parental history of hypertension, cigarette smoking, alcohol consumption, and diet, white men in the highest quartile of leisure activity (primarily cycling and walking) had a 34% lower odds of developing hypertension over 6 years compared to the least active (OR = 0.66, 95% CI = 0.47-0.94; P for quartile trend = 0.01). Baseline activity was not associated with incident hypertension in white women or blacks. CONCLUSIONS: Leisure-time physical activity reduces the odds of hypertension in middle-aged white men. Additional studies in women and blacks are needed.  相似文献   
57.
58.
The immune response to an allograft varies from one individual to another. This individual variation is, at least in part, due to genetic variation in the regulation of cytokine gene expression. High and low cytokine responses in vitro for tumour necrosis factor-alpha (TNF-alpha), transforming growth factor-beta 1 (TGF-beta1) and other cytokines can be predicted from an individual's cytokine genotype. Using the same genetic markers we have been able to show associations, in particular between TNF-alpha genotype of the recipient and acute allograft rejection and, similarly, between TGF-beta1 genotype and chronic rejection. The ability to identify high and low responders to allografts by a simple genetic test, and to predict who will suffer acute and chronic rejection, has implications for donor selection and recipient treatment as well as for the design and interpretation of clinical trials of new immunosuppressive agents.  相似文献   
59.
BACKGROUND AND PURPOSE: MR imaging has revealed putative evidence of subclinical cerebrovascular disease (CVD) as reflected by white matter signal changes and infarct-like lesions (ILLs). Nonetheless, the prevalence of this condition in the general population has been defined only to a limited extent. We herein report the prevalence and anatomic characteristics of ILLs seen on cranial MR images obtained as part of a population-based study of cardiovascular disease in middle-aged adults. These results are contrasted to those of previous similar studies, particularly those of an elderly population in the Cardiovascular Health Study (CHS). METHODS: This Atherosclerosis Risk in Communities (ARIC) cohort consists of a probability sample of community-living persons who were 55 to 72 years old at the time of MR examination. MR imaging of 1890 participants was performed at two ARIC field centers, based on a common protocol. MR studies were evaluated by trained readers at the MR Reading Center using original digital data displayed on a high-resolution workstation. The measures of lesion size, anatomic location, and signal intensity were collected. The definition for an ILL was a non-mass, hyperintense region with an arterial vascular distribution on spin-density and T2-weighted images. RESULTS: Two hundred ninety participants had ILLs, for an overall prevalence of 15.3%. Eighty-two percent of participants with ILLs had lesions that were 3 mm or larger in maximal dimension, although 87% of these lesions were 20 mm or smaller in maximal dimension. The prevalence of ILLs increased with age, from 7.9% in the 55- to 59-year-old age group to 22.9% in the 65- to 72-year-old age group (P < .001). Lesion prevalence was greater in black (20.7%) than in white persons (10.2% [P < .0001]), but did not differ significantly between male and female participants. The basal ganglia and thalamic region was the most commonly affected anatomic site, accounting for 78.9% of the lesions. CONCLUSION: Considering that the prevalence of self-reported stroke or transient ischemic attack in ARIC participants is 1.5%, these results suggest that there is significantly more subclinical than clinical CVD in the general population. Furthermore, the prevalence of this subclinical disease increases with age, and is greater in black persons. ILLs are dominated by "lacunae" in the basal ganglia and thalamus. These results are, in general, similar to those of a comparable study of elderly participants in the CHS, except for a 60% lower prevalence of ILLs in this younger population.  相似文献   
60.
Interleukin-10 (IL10) is an anti-inflammatory cytokine which may modulate disease expression in multiple sclerosis (MS). Three dimorphic polymorphisms within the IL10 promoter region at positions - 1082, -819 and -519 have previously been identified. The - 1082*A allele has been associated with low and the - 1082*G allele with high in vitro IL10 production. We have genotyped 185 Caucasian MS patients and 211 ethnically matched controls for each of these three dimorphisms. MS patients were stratified for severity of disease outcome. No associations were found for any IL10 promoter polymorphisms when the MS cases were compared with controls or with disease outcome with regards to disability. IL10 polymorphism does not appear to be associated with MS or to influence disease progression.  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