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   4914篇
  免费   243篇
  国内免费   46篇
耳鼻咽喉   43篇
儿科学   143篇
妇产科学   64篇
基础医学   697篇
口腔科学   95篇
临床医学   354篇
内科学   872篇
皮肤病学   86篇
神经病学   541篇
特种医学   109篇
外科学   594篇
综合类   15篇
预防医学   736篇
眼科学   108篇
药学   347篇
中国医学   15篇
肿瘤学   384篇
  2023年   26篇
  2022年   41篇
  2021年   82篇
  2020年   53篇
  2019年   80篇
  2018年   71篇
  2017年   59篇
  2016年   81篇
  2015年   82篇
  2014年   132篇
  2013年   180篇
  2012年   282篇
  2011年   309篇
  2010年   153篇
  2009年   132篇
  2008年   307篇
  2007年   308篇
  2006年   295篇
  2005年   284篇
  2004年   275篇
  2003年   249篇
  2002年   228篇
  2001年   121篇
  2000年   113篇
  1999年   98篇
  1998年   52篇
  1997年   47篇
  1996年   33篇
  1995年   35篇
  1994年   29篇
  1993年   24篇
  1992年   65篇
  1991年   52篇
  1990年   83篇
  1989年   68篇
  1988年   52篇
  1987年   49篇
  1986年   71篇
  1985年   45篇
  1984年   34篇
  1983年   38篇
  1979年   37篇
  1978年   24篇
  1976年   19篇
  1975年   20篇
  1974年   21篇
  1973年   19篇
  1972年   22篇
  1969年   27篇
  1967年   20篇
排序方式: 共有5203条查询结果,搜索用时 31 毫秒
121.
AIMS: To compare interferon monotherapy with its combination with lamivudine for hepatitis B e antigen (HBeAg)-positive hepatitis B treatment. METHODS: Two independent researchers identified pertinent randomized controlled trials. The trials were evaluated for methodological quality and heterogeneity. Rates of sustained virological and biochemical responses, and HBeAg clearance and seroconversion were used as primary efficacy measures. Quantitative meta-analyses were conducted to assess differences between groups for conventional and pegylated interferon, and overall. RESULTS: Greater sustained virological, biochemical and seroconversion rates were observed with addition of lamivudine to conventional [odds ratio (OR)=3.1, 95% confidence intervals (CI) (1.7-5.5), P<0.0001, OR=1.8, 95% CI (1.2-2.7), P=0.007 and OR=1.8, 95% CI (1.1-2.8), P=0.01 respectively], although not pegylated [OR=1.1, 95% CI (0.5-2.3), P=0.8, OR=1.0, 95% CI (0.7-1.3), P=0.94, and OR=0.9, 95% CI (0.6-1.2), P=0.34 respectively] interferon-alpha, with no significant affect on HBeAg clearance rates [OR=1.6, 95% CI (0.9-2.7), P=0.09, and OR=0.8, 95% CI (0.6-1.1), P=0.26 respectively]. Excluding virological response (P<0.001), pegylated interferon monotherapy and conventional interferon and lamivudine combination therapy were similarly efficacious (P>0.05), with the former studied in harder to treat patients, as evidenced by the superior virological response observed with conventional as compared with pegylated interferon monotherapy (P<0.0001). CONCLUSION: In comparable populations, pegylated interferon monotherapy is likely to be equally or more efficacious than conventional interferon and lamivudine combination therapy, thus constituting the treatment of choice, with no added benefit with lamivudine addition. However, when conventional interferon is used, its combination with lamivudine should be considered.  相似文献   
122.
BACKGROUND: Psychosocial stressors such as job strain and marital stress have been associated with a sustained increase in blood pressure (BP). METHODS: We evaluated whether job strain and marital cohesion were associated with ambulatory BP in workers with normal or untreated elevated BP using baseline data from the Double Exposure study. The study population included 248 male and female volunteers who were nonmedicated, employed, and living with a significant other, all for a minimum of 6 months. Blood pressure was measured with an ambulatory BP monitor and participants completed a diary that recorded time during work, spousal contact, and sleep. Job strain and marital cohesion were calculated from the Job Content Questionnaire and the Dyadic Adjustment Scale, respectively. RESULTS: Of the subjects, 54.4% were female with a mean age of 50.8 years (6.6, SD). In all, 21.3% reported job strain. Significant assocations were found between 24-h systolic BP (SBP) and alcohol consumption (P = .033), job strain (P = .007), male gender (P = .004), and age (P = .039) and was inversely associated with exercise (P = .037). An interaction between 24-h SBP, job strain, and marital cohesion was found such that greater marital cohesion was associated with lower SBP in subjects with job strain. CONCLUSIONS: Psychosocial factors may influence the development of early hypertension. This should be clarified by the cohort phase of the Double Exposure study.  相似文献   
123.
OBJECTIVE: To gain insight into the mechanisms of the antiinflammatory effect of tumor necrosis factor alpha (TNFalpha)-induced protein 6 (Tnfip6) in arthritis, using Tnfip6-deficient animals. METHODS: TNFalpha-stimulated gene 6 (TSG-6) coding for Tnfip6 was disrupted. Tnfip6-deficient mice were backcrossed into proteoglycan-induced arthritis (PGIA)-susceptible BALB/c mice, and arthritis was induced by systemic immunization with cartilage proteoglycan (PG). Thioglycollate-induced sterile peritonitis was also assessed, to monitor the early events of neutrophil extravasation in wild-type and Tnfip6-deficient mice in the presence or absence of treatment with recombinant murine Tnfip6. RESULTS: The onset of PGIA was similar, but progression and severity were significantly greater, in Tnfip6-deficient mice compared with wild-type BALB/c mice. However, this was not associated with enhanced T or B cell responses to cartilage PGs, but rather, an early and more extensive infiltration of the synovium with neutrophil leukocytes was the most prominent histopathologic feature of PGIA in Tnfip6-deficient mice. This was accompanied by elevated serum levels of interleukin-6 and amyloid A, and significantly increased activities of the enzymes plasmin, myeloperoxidase, and neutrophil elastase in the inflamed paw joints of Tnfip6-null mice, when compared with that of the wild-type littermates. Loss of control over several components of inflammation resulted in extensive and rapid cartilage degradation, bone erosion, joint ankylosis, and deformities in Tnfip6-null animals. In support of the antiinflammatory effect of Tnfip6 via the inhibition of polymorphonuclear (PMN) cell efflux, neutrophil invasion during thioglycollate-induced peritonitis was 2-fold higher in Tnfip6-deficient animals than in wild-type animals, but was dramatically suppressed by intravenous injection of recombinant murine Tnfip6. CONCLUSION: Tnfip6 is a multifunctional antiinflammatory protein that is produced at the site of inflammation and can be retained by the hyaluronan-rich extracellular matrix. A major effect of Tnfip6 is the inhibition of the extravasation of PMN cells, predominantly neutrophils, into the site of inflammation, most likely via a CD44/hyaluronan/Tnfip6-mediated blocking mechanism.  相似文献   
124.
Drosophila homolog of the murine Int-1 protooncogene.   总被引:3,自引:0,他引:3       下载免费PDF全文
We have isolated phage clones from Drosophila melanogaster genomic and cDNA libraries containing a sequence homologous to the murine Int-1 protooncogene. The Drosophila gene is represented by a single locus at position 28A1-2 on chromosome 2. The gene is expressed as a 2.9-kilobase-long polyadenylylated mRNA in embryo, larval, and pupal stages. It is hardly detectable in adult flies. The longest open reading frame of the cDNA clone corresponds to a protein 469 amino acids long. Alignment of the predicted amino acid sequences shows that the Drosophila protein is 86 amino acids longer than its murine counterpart. In spite of the difference in length, the two proteins are highly conserved with an overall sequence homology of 54%. Both Drosophila and murine Int-1 proteins begin with a hydrophobic leader sequence and contain cysteine residues and sites for glycosylation (four in the murine protein and one in the Drosophila protein) in conserved positions, suggesting that they play important functional roles.  相似文献   
125.
T cells are involved in control of coronavirus disease 2019 (COVID-19), but limited knowledge is available on the relationship between antigen-specific T cell response and disease severity. Here, we used flow cytometry to assess the magnitude, function, and phenotype of SARS coronavirus 2–specific (SARS-CoV-2–specific) CD4+ T cells in 95 hospitalized COVID-19 patients, 38 of them being HIV-1 and/or tuberculosis (TB) coinfected, and 38 non–COVID-19 patients. We showed that SARS-CoV-2–specific CD4+ T cell attributes, rather than magnitude, were associated with disease severity, with severe disease being characterized by poor polyfunctional potential, reduced proliferation capacity, and enhanced HLA-DR expression. Moreover, HIV-1 and TB coinfection skewed the SARS-CoV-2 T cell response. HIV-1–mediated CD4+ T cell depletion associated with suboptimal T cell and humoral immune responses to SARS-CoV-2, and a decrease in the polyfunctional capacity of SARS-CoV-2–specific CD4+ T cells was observed in COVID-19 patients with active TB. Our results also revealed that COVID-19 patients displayed reduced frequency of Mycobacterium tuberculosis–specific CD4+ T cells, with possible implications for TB disease progression. These results corroborate the important role of SARS-CoV-2–specific T cells in COVID-19 pathogenesis and support the concept of altered T cell functions in patients with severe disease.  相似文献   
126.
127.
Malignant mesothelioma (MM) is a connective tissue tumor with partial epithelioid differentiation. The pattern of proteoglycan (PG) expression by epithelioid and fibroblast-like (sarcomatoid) MM cells differ; cell surface PGs being more abundant in the former phenotype and matrix PGs in the latter. The differentiation as well as much of the malignant nature of these tumors is dependent on the expression of surface PGs. The syndecans, however, also translocate to the nucleus for an as yet unknown function.  相似文献   
128.
ObjectivesThis study examined whether late-onset (versus early-onset) suicidal behavior is associated with worse cognition.MethodsParticipants included 278 adults aged 50+ years (56 nonpsychiatric comparison group; 67 nonsuicidal depressed older adults; 63 depressed suicide ideators; and 44 late-onset (55+ years) and 48 early-onset suicide attempters (<55 years). Using a case-control design, this study examined group differences in global cognition, episodic memory, information processing speed, and executive functioning, assessed using the Repeatable Battery of Neuropsychological Status and the Trail Making Test from the Delis-Kaplan Executive Function System. Linear regression was used for data analyses.ResultsBoth attempter groups displayed worse executive functioning than nonsuicidal depressed older adults. Late-onset attempters additionally displayed poorer global cognition and processing speed than nonsuicidal depressed older adults and poorer memory than early-onset attempters.ConclusionsLate-onset suicidal behavior is associated with worse performance in a broad range of cognitive domains, possibly reflective of a dementia prodrome.  相似文献   
129.
130.
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