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   77291篇
  免费   7128篇
  国内免费   166篇
耳鼻咽喉   890篇
儿科学   2555篇
妇产科学   2220篇
基础医学   11370篇
口腔科学   1453篇
临床医学   10224篇
内科学   14553篇
皮肤病学   1217篇
神经病学   7075篇
特种医学   2180篇
外国民族医学   1篇
外科学   9149篇
综合类   1246篇
一般理论   61篇
预防医学   8467篇
眼科学   1224篇
药学   5508篇
中国医学   117篇
肿瘤学   5075篇
  2023年   430篇
  2022年   745篇
  2021年   1517篇
  2020年   975篇
  2019年   1630篇
  2018年   1813篇
  2017年   1282篇
  2016年   1530篇
  2015年   1601篇
  2014年   2233篇
  2013年   3339篇
  2012年   4728篇
  2011年   4837篇
  2010年   2700篇
  2009年   2315篇
  2008年   4019篇
  2007年   4274篇
  2006年   4152篇
  2005年   3987篇
  2004年   3672篇
  2003年   3484篇
  2002年   3448篇
  2001年   1785篇
  2000年   1761篇
  1999年   1592篇
  1998年   925篇
  1997年   788篇
  1996年   641篇
  1995年   654篇
  1994年   587篇
  1993年   590篇
  1992年   1223篇
  1991年   1140篇
  1990年   1097篇
  1989年   1012篇
  1988年   950篇
  1987年   938篇
  1986年   911篇
  1985年   924篇
  1984年   757篇
  1983年   653篇
  1982年   479篇
  1981年   391篇
  1980年   410篇
  1979年   611篇
  1978年   475篇
  1977年   385篇
  1976年   385篇
  1974年   393篇
  1972年   352篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
41.
Diacetyl is a diketone flavouring agent that is commonly employed for buttery taste as well as other purposes. Industrial exposure to flavouring agents, particularly diacetyl, has recently been associated with bronchiolitis obliterans, a severe respiratory illness producing fibrosis and obstruction of the small airways. This has been most commonly reported in the microwave popcorn production industry, but it has occurred elsewhere. In addition to bronchiolitis obliterans, spirometry abnormalities (fixed airflow obstruction) and respiratory symptoms have been associated with exposure. A direct effect on the respiratory epithelium with the disorganised fibrotic repair appears most likely as the underlying mechanism. Current data suggest that diacetyl is the agent responsible, although it is possible that diacetyl is simply a marker for another causative agent.  相似文献   
42.
In this review, we critically evaluate the evidence for local IgE production in allergic rhinitis mucosa and the concept of local allergy in non-atopic idiopathic rhinitis. Significantly, fewer studies have focused on the disease pathways associated with non-allergic rhinitis compared with their allergic counterparts. Recently, there's been a revival of the hypothesis concerning the existence of local tissue-specific allergic disease confined to the nasal mucosa of some systemically non-atopic rhinitis subjects. Providing the evidence for local mucosal IgE production in allergic rhinitis is a pre-requisite to reviewing its existence in non-allergic rhinitis. In addition, practical and theoretical approaches useful in the detection of allergy in non-allergic rhinitis will be discussed. Furthermore, successful therapeutic regimens used in the treatment of non-allergic rhinitis will be examined as these could provide an insight into the underlying pathophysiology of this common but poorly understood disease.  相似文献   
43.
Abstract   We evaluated the associations between glycemic therapies and prevalence of diabetic peripheral neuropathy (DPN) at baseline among participants in the Bypass Angioplasty Revascularization Investigation 2 Diabetes (BARI 2D) trial on medical and revascularization therapies for coronary artery disease (CAD) and on insulin-sensitizing vs. insulin-providing treatments for diabetes. A total of 2,368 patients with type 2 diabetes and CAD was evaluated. DPN was defined as clinical examination score >2 using the Michigan Neuropathy Screening Instrument (MNSI). DPN odds ratios across different groups of glycemic therapy were evaluated by multiple logistic regression adjusted for multiple covariates including age, sex, hemoglobin A1c (HbA1c), and diabetes duration. Fifty-one percent of BARI 2D subjects with valid baseline characteristics and MNSI scores had DPN. After adjusting for all variables, use of insulin was significantly associated with DPN (OR = 1.57, 95% CI: 1.15–2.13). Patients on sulfonylurea (SU) or combination of SU/metformin (Met)/thiazolidinediones (TZD) had marginally higher rates of DPN than the Met/TZD group. This cross-sectional study in a cohort of patients with type 2 diabetes and CAD showed association of insulin use with higher DPN prevalence, independent of disease duration, glycemic control, and other characteristics. The causality between a glycemic control strategy and DPN cannot be evaluated in this cross-sectional study, but continued assessment of DPN and randomized therapies in BARI 2D trial may provide further explanations on the development of DPN.  相似文献   
44.
45.
46.
Contrary to popular beliefs, a recent empirical study using eye tracking has shown that a non-clinical sample of socially anxious adults did not avoid the eyes during face scanning. Using eye-tracking measures, we sought to extend these findings by examining the relation between stable shyness and face scanning patterns in a non-clinical sample of 11-year-old children. We found that shyness was associated with longer dwell time to the eye region than the mouth, suggesting that some shy children were not avoiding the eyes. Shyness was also correlated with fewer first fixations to the nose, which is thought to reflect the typical global strategy of face processing. Present results replicate and extend recent work on social anxiety and face scanning in adults to shyness in children. These preliminary findings also provide support for the notion that some shy children may be hypersensitive to detecting social cues and intentions in others conveyed by the eyes. Theoretical and practical implications for understanding the social cognitive correlates and treatment of shyness are discussed.  相似文献   
47.

Background  

Long-term survival for combined aortic and mitral valve replacement appears to be determined by the mitral valve prosthesis from our previous studies. This 21-year retrospective study assess long-term outcome and durability of aortic valve replacement (AVR) with either concomitant mitral valve replacement (MVR) or mitral valve repair (MVrep). We consider only a single mechanical prosthesis.  相似文献   
48.
Regional cerebral [11C]3-O-methyl-D-glucose ([11C]MeG) uptake kinetics have been measured in five insulin-dependent diabetic patients and four normal controls using positron emission tomography (PET). Concomitant measurement of regional cerebral blood volume and CBF enabled corrections for the presence of intravascular [11C]MeG signal in cerebral regions of interest to be carried out, and regional cerebral [11C]MeG unidirectional extraction fractions to be computed. Four of the five diabetic subjects were studied with their fasting plasma glucose level clamped at a normoglycaemic level (4 mM), and four were studied at hyperglycaemic plasma glucose levels (mean 13 mM). The four diabetic subjects whose fasting plasma glucose levels were clamped at a normoglycaemic level of 4 mM had mean fasting whole-brain, cortical, and white matter [11C]MeG extraction fractions of 15, 15, and 16%, respectively, values similar to those found for the four normal controls (whole brain, 14%; cortex, 13%; white matter, 17%). Mean regional cerebral [11C]MeG extraction fractions were significantly reduced in diabetic subjects during hyperglycaemia whether their plasma insulin levels were undetectable or whether they were raised by continuous intravenous insulin infusion. Such a reduction in [11C]MeG extraction under hyperglycaemic conditions can be explained entirely in terms of increased competition between [11C]MeG and D-glucose for the passive facilitated transport carrier system for hexoses across the blood-brain barrier (BBB). It is concluded that the number and affinity of D-glucose carriers present in the BBB are within normal limits in treated insulin-dependent diabetic subjects. In addition, insulin appears to have no effect on the transport of D-glucose across the BBB.  相似文献   
49.
The present status of total colectomy with ileorectal anastomosis in the surgical treatment of inflammatory bowel disease is examined. Special reference is made to the different indications for the use of the operation in Crohn's disease and in ulcerative colitis. The late results are illustrated by the outcome in the 59 patients in a personal series, and other published results.  相似文献   
50.
In order to establish a venom fingerprint and a peptide profile of the Lasiodora parahybana tarantula venom gland, we used conventional methods such as reversed phase liquid chromatography coupled to an electrospray-ionisation hybrid quadrupole time of flight mass spectrometer (LC/ESI-QqTOFMS), matrix-assisted laser desorption/ionization time-of-flight-MS (MALDI-TOFMS) and direct study of L. parahybana venom by nanospray-ionization QqTOFMS (nanoESI-QqTOFMS) and a new technology for the direct analysis of fresh tissues using MALDI-TOFMS. The analysis of the crude venom allowed the characterization of specific juvenile and adult biomarkers. In situ MALDI analysis of L. parahybana venom gland sections revealed different peptide expression levels all along the gland and non-processed peptide precursors, demonstrating the power of the method for the dynamic investigation of peptide evolution in the venom gland of spiders.  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