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   8580篇
  免费   400篇
  国内免费   34篇
耳鼻咽喉   208篇
儿科学   219篇
妇产科学   94篇
基础医学   1075篇
口腔科学   165篇
临床医学   553篇
内科学   1868篇
皮肤病学   298篇
神经病学   725篇
特种医学   327篇
外科学   1055篇
综合类   50篇
预防医学   307篇
眼科学   142篇
药学   758篇
中国医学   32篇
肿瘤学   1138篇
  2023年   49篇
  2022年   91篇
  2021年   193篇
  2020年   105篇
  2019年   104篇
  2018年   135篇
  2017年   111篇
  2016年   121篇
  2015年   131篇
  2014年   210篇
  2013年   234篇
  2012年   390篇
  2011年   429篇
  2010年   264篇
  2009年   229篇
  2008年   405篇
  2007年   468篇
  2006年   449篇
  2005年   390篇
  2004年   456篇
  2003年   384篇
  2002年   376篇
  2001年   261篇
  2000年   281篇
  1999年   288篇
  1998年   101篇
  1997年   90篇
  1996年   86篇
  1995年   86篇
  1994年   77篇
  1993年   60篇
  1992年   195篇
  1991年   183篇
  1990年   157篇
  1989年   164篇
  1988年   142篇
  1987年   139篇
  1986年   142篇
  1985年   91篇
  1984年   88篇
  1983年   69篇
  1982年   42篇
  1980年   32篇
  1979年   52篇
  1978年   36篇
  1975年   35篇
  1972年   34篇
  1969年   33篇
  1967年   40篇
  1966年   36篇
排序方式: 共有9014条查询结果,搜索用时 15 毫秒
51.
The efficacy of TCR antagonist peptides in inhibition of antigen-specific antibody production and T cell responses in vivo was evaluated. Among amino acid-substituted analogs of a peptide corresponding to residues 119 - 133 of bovine beta-lactoglobulin (p119 - 133), pR124Q and pD129S, prepared by substitution of Gln and Ser for Arg(124) and Asp(129), respectively, have been shown to display TCR antagonist activity for three out of four distinct p119 - 133-specific T cell clones and for polyclonal T cells derived from p119 - 133-immunized C57BL / 6 mice. Both pD129S and pR124Q inhibited in vivo priming and subsequent activation of T cells by p119 - 133 when co-injected with p119 - 133 into mice, as shown by the decreased proliferation of T cells in response to p119-133 in vitro. pD129S significantly inhibited production of anti-p119 - 113 antibodies of IgG1, IgG2b and IgE isotype in vivo when co-injected into mice together with p119 - 133 at the time of the first immunization. However, pR124Q was totally ineffective in inhibition of the antibody responses. Anti-p119 - 133 antibodies from p119 - 133-immunized mice could bind to pR124Q but not to pD129S, suggesting that the difference in cross-reactivity is responsible for the different effect of these two peptides on specific antibody production. Our findings demonstrate that a single TCR antagonist peptide can inhibit antigen-specific polyclonal antibody production when this antagonist peptide does not cross-react with the antibody elicited in response to an antigenic peptide.  相似文献   
52.
We report on a female baby with Fryns syndrome who died soon after birth. The patient had short limbs, coarse face, hypoplastic lungs, diaphragmatic hernia, and acral hypoplasia. Literature review disclosed varying degrees of skeletal manifestations in Fryns syndrome; short limbs may be a component of Fryns syndrome. © 1995 Wiley-Liss, Inc.  相似文献   
53.
54.
Summary Two cases of renal epithelial tumours are reported in females aged 46 and 66 years respectively. In spite of the large size of the tumours, neither invasive growth nor metastasis was observed. Histologically, the tumours were composed of immature epithelial cells forming tubules with abortive glomeruloid structures. Electron microscopy of tumour cells revealed poorly developed polarity and intracytoplasmic organelles. They showed similar immunohistochemical reactions to those of developing nephrons, particularly to those of the S-shaped body. The nuclear DNA content of the tumour cells was almost euploid. We conclude that the lesions were epithelial tumours of the kidney histologically mimicking developing renal parenchyma.  相似文献   
55.
BACKGROUND: In evidence-based medicine, stratum-specific likelihood ratios (SSLRs) are now being increasingly recognized as a more convenient and generalizable method to interpret diagnostic information than an optimal cut-off and its associated sensitivity and specificity. We previously examined the SSLRs of the General Health Questionnaire (GHQ) in primary care settings. The present paper aims to examine if these SSLRs are generalizable to the community settings. METHODS: The Composite International Diagnostic Interview (CIDI) and the GHQ were administered on a representative sample of the Australian population in the Australian National Survey of Mental Health and Well-Being. We first compared the SSLRs of GHQ in urban Australia with the estimates that we had previously obtained from the developed urban centres in the WHO Psychological Problems in General Health Care study. If the SSLRs in the community were found to differ significantly from those in the primary care, we sought for explanatory variables. RESULTS: The SSLRs in urban Australia and in the urban centres in the WHO study were significantly different for three out of the six strata. When we limited the sample to those with physical problems who visited a health professional, however, the SSLRs in the Australian study were strikingly close to those observed for primary care settings. CONCLUSIONS: Different sets of SSLRs apply to primary care and general population samples. For general population surveys in developed countries, the results of the Australian National Survey represent the currently available best estimates. For developing countries or rural areas, the results are less definitive and an investigator may wish to conduct a pilot study.  相似文献   
56.
Previous fate mapping analysis, using Cre recombinase driven by the Mesp1 locus, revealed that Mesp1 is expressed in almost all of the precursors of the cardiovascular system, including the endothelium, endocardium, myocardium, and epicardium. Mesp1-nonexpressing cells were found to be restricted to the outflow tract cushion and along the interventricular septum (IVS), which is a location that is suggestive of specialized cardiac conduction system (CCS). In our current study, we examined the identity of these IVS cells by using the pattern of beta-galactosidase activity in CCS-lacZ mice. In addition, by crossing Mesp1-Cre and floxed GFP reporter mice with CCS-lacZ mice, we have calculated that approximately 20% of the ventricular CCS within the IVS corresponds to Mesp1-nonexpressing cells. These data suggest that the ventricular CCS is of heterocellular origin. Furthermore, we indicate a possibility that a population of the cells that contribute to the ventricular CCS might be distinguished at an early stage of development.  相似文献   
57.
T Furukawa  J H Jean  S A Plotkin 《Virology》1978,85(2):622-625
Replication of poliovirus in human cytomegalovirus (CMV)-infected cells is enhanced 5-to 10-fold over replication in uninfected cells. Enhanced poliovirus replication in dually infected cells was not due to a difference in adsorption on infected cells and was supported by evidence of increased synthesis of polio-specific RNA. A functional CMV genome appeared to be required for the enhancement of polio replication since enhanced replication was not seen in cells infected with uv-irradiated CMV or in cultures treated with the inhibitors of CMV replication. Enhanced polio replication in CMV-infected cells may be due to the enhanced cellular metabolism in these cells.  相似文献   
58.
Role of cytokines in autoimmune myocarditis and cardiomyopathy   总被引:3,自引:0,他引:3  
Cellular as well as humoral autoimmune responses are critically associated with the pathogenesis and progression of myocarditis and cardiomyopathy. Cytokines appear to play critical roles in accentuating or regulating autoimmune mechanisms in these disorders. However, depending on the triggers of autoimmune responses against the heart, such as viral or parasitic infections and experimental immunization with cardiac myosin, the effect of each cytokine on autoimmune myocardial disease may vary. Cytokines may represent new therapeutic targets in the treatment and prevention of autoimmunity-mediated myocarditis and cardiomyopathy, though the etiology and variability in the type of autoimmune responses should be taken into account in the development of cytokine/anti-cytokine treatment of these disorders.  相似文献   
59.
60.
Zusammenfassung Mit Hilfe der kultivierten Fibroblasten aus Hautbiopsiematerial gelingt es, vor dem Auftreten anderer biochemischer Veränderungen zu klären, ob in einer mit Cystinose belasteten Familie ein junger Säugling, der noch keine klinischen Symptome bietet, an Cystinose leidet. Das Cystin erreicht in den Fibroblasten Cystinosekranker Konzentrationen von etwa 5–11 Mol1/2 Cystin/g Protein, während normale Fibroblasten nur Spuren von Cystin enthalten. Damit ist eine verläßliche Methode zur Frühdiagnose gegeben, die eine diätetische Therapie zu einem Zeitpunkt erlaubt, wo die irreversible Tubulopathie noch gering ist.
Summary It is possible to diagnose cystinosis in young infants from families, where cystinosis is known, by culturing fibroblasts from skin biopsy material before any biochemical or clinical symptoms are evident. Fibroblasts from patients suffering from cystinosis show a high content of about 5–11 Mol1/2 cystine/g protein, while normal fibroblasts only have traces of cystine.This is a very reliable method for early diagnosis and dietetic therapy can be started before any damage has been done to the tubuli.
  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