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   16285篇
  免费   1158篇
  国内免费   37篇
耳鼻咽喉   73篇
儿科学   618篇
妇产科学   382篇
基础医学   2429篇
口腔科学   137篇
临床医学   2434篇
内科学   3012篇
皮肤病学   253篇
神经病学   1434篇
特种医学   282篇
外科学   1328篇
综合类   196篇
一般理论   33篇
预防医学   2082篇
眼科学   375篇
药学   997篇
中国医学   38篇
肿瘤学   1377篇
  2024年   22篇
  2023年   157篇
  2022年   196篇
  2021年   385篇
  2020年   289篇
  2019年   393篇
  2018年   431篇
  2017年   345篇
  2016年   404篇
  2015年   409篇
  2014年   554篇
  2013年   852篇
  2012年   1212篇
  2011年   1319篇
  2010年   705篇
  2009年   642篇
  2008年   1142篇
  2007年   1118篇
  2006年   1121篇
  2005年   1099篇
  2004年   962篇
  2003年   879篇
  2002年   843篇
  2001年   127篇
  2000年   92篇
  1999年   133篇
  1998年   175篇
  1997年   136篇
  1996年   137篇
  1995年   126篇
  1994年   96篇
  1993年   104篇
  1992年   65篇
  1991年   62篇
  1990年   56篇
  1989年   40篇
  1988年   56篇
  1987年   35篇
  1986年   32篇
  1985年   43篇
  1984年   45篇
  1983年   41篇
  1982年   42篇
  1981年   39篇
  1980年   41篇
  1979年   23篇
  1978年   24篇
  1975年   32篇
  1974年   22篇
  1973年   21篇
排序方式: 共有10000条查询结果,搜索用时 58 毫秒
61.
The salivary glands are the major sites of persistent replication of rat cytomegalovirus (RCMV). At several months post infection (pi), infectious RCMV is usually still produced in the salivary glands but not in any other organ or tissue of the rat. To investigate whether the persistence of RCMV in the salivary glands is crucial to the pathogenesis of viral infection, we monitored the progression of RCMV-induced disease in rats from which the salivary glands had been surgically removed (desalivated) as well as in sham-operated rats, both after a lethal and sublethal challenge with RCMV. Desalivation did not have a significant effect on either RCMV-induced morbidity or mortality. As expected, at 1 year pi, relatively high levels of infectious virus were detected in the salivary glands of sham-operated rats, whereas neither infectious virus nor RCMV DNA could be detected in liver, spleen and lungs of these animals. Infectious virus and viral DNA were also undetectable in organs from desalivated animals at 1 year pi. Surprisingly, a difference was found between desalivated and sham-operated rats in the titers of anti-RCMV IgG antibodies, which were significantly higher in sham-operated rats than in desalivated animals at 183, 295 and 365 days pi. This finding indicates that the persistence of RCMV in the salivary glands may contribute significantly to the anti-RCMV humoral immunity of infected rats.  相似文献   
62.
It is not certain which protein kinase (A, C or both) is involved in the acute phase of β-endorphin (β-EP) release stimulated in the corticotrope by vasopressin (VP) and corticotropin-releasing factor (CRF). We have employed an isolated ovine anterior pituitary cell superfusion system to determine the dynamic effects of forskolin, a protein kinase A (PKA) stimulator, and phorbol 12-myristate 13-acetate (PMA), a protein kinase C (PKC) activator. Both secretagogues stimulated β-EP release within 5 min and therefore both PKA and PKC are potential mediators of the acute phase of hormonal stimulation of the corticotrope. Pretreatment with PMA specifically desensitized the pituitary cell columns to subsequent PMA exposure while not significantly altering sensitivity to forskolin or 50 mM KCl.  相似文献   
63.
64.
Prevention Science - The NAMWEZA intervention was implemented, using a ten-session group format, to build skills targeting psychosocial vulnerabilities and enhancing HIV prevention among people...  相似文献   
65.
Journal of Occupational Rehabilitation - Purpose Little is currently known about how early intervention vocational rehabilitation (EIVR) works for people with newly acquired neurological conditions...  相似文献   
66.
Journal of Immigrant and Minority Health - Although multiple studies have shown that resettled refugee women are less likely to receive preventative cancer screenings like pap smears and...  相似文献   
67.
Neurosurgical Review - Treatment options for hydrocephalus include endoscopic third ventriculostomy (ETV) and ventriculoperitoneal shunt (VPS). Some ambiguity remains regarding indications, safety,...  相似文献   
68.
BackgroundCystic Fibrosis (CF) is a multi-systemic disorder resulting from genetic variation in the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) gene which can result in bronchiectasis, chronic sinusitis, pancreatic malabsorption, cholestatic liver disease and distal intestinal obstructive syndrome. This study generates multi-dimensional clinical phenotypes that capture the complexity and spectrum of the disease manifestations seen in adult CF patients using statistically robust techniques.MethodsPre-transplant clinical data from adult (age ≥18 years) CF patients (n = 992) seen in six regionally distinct US CF centers between 1/1/2014 and 6/30/2015 were included. Demographic, spirometry, nutritional, microbiological and therapy data were used to generate clusters using the Random Forests statistical-learning and Partitioning around Medoids (PAM) clustering algorithms. Five commonly measured demographic, physiological and nutritional parameters were needed to create the final phenotypes that are highly similar to a regionally matched group of patients from the CF Foundation Patient RegistryResultsThis approach identified high-risk phenotypes with expected characteristics including high rates of pancreatic insufficiency, diabetes and Pseudomonas aeruginosa colonization. It also identified unexpected populations including a) a male-dominated, well-nourished group with good lung function with a high prevalence of severe genotypes (i.e. 60% subjects had two minimal function CFTR variations), b) and an older, “survivor” phenotype that had high rates of chronic P. aeruginosa infection.ConclusionsThis study identified recognizable phenotypes that capture the clinical complexity in a statistically robust manner and which may aide in the identification of specific genetic and environmental factors responsible for these disease manifestation patterns.  相似文献   
69.
Sexuality and Disability - Every individual should have equal access to sexuality-related information and services. Regrettably, societal stigma revolves around the sexuality of youth with...  相似文献   
70.
Papillary carcinomas (PCs) of thyroid are among the most common but least aggressive human malignancies. The factors explaining the indolence of these tumors are unknown but host-tumor immune interactions may play a role. This study was designed to determine if there is morphologic evidence of these. Frozen tissues collected from 21 PCs, 4 follicular adenomas (FAs), 4 follicular carcinomas (FCs), and 11 nodular hyperplasias (NHs) were stained immunohistochemically for HLA-D antigens, lymphocyte and macrophage markers; results were graded numerically. Paraffin-embedded tumors (35 PCs, 10 FAs, and 10 FCs) were stained for S-100 protein to detect Langerhans' cells (LCs). Diffuse staining for HLA-D antigens and heavy mononuclear infiltrates were found more commonly in PCs compared to follicular neoplasms (FNs) or NHs. No consistent relationship was found between lymphocyte/macrophage infiltrates and expression of HLA-D antigens. The largest number of LCs was in PCs (median 11.8 cells/standard microscopic field [c/smf]), fewer cells were found in FA (3.7 c/smf), and the least in FC (0.05 c/smf). Features of host-tumor interaction including HLA-D expression and infiltrates with lymphocyte macrophages and LC are more strongly expressed in PC than other tumors. This may play a role in explaining their biological behavior.  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