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   348篇
  免费   30篇
  国内免费   1篇
耳鼻咽喉   2篇
儿科学   21篇
妇产科学   4篇
基础医学   54篇
口腔科学   29篇
临床医学   40篇
内科学   81篇
皮肤病学   11篇
神经病学   4篇
特种医学   57篇
外科学   32篇
综合类   9篇
预防医学   7篇
药学   15篇
  1篇
肿瘤学   12篇
  2022年   1篇
  2021年   3篇
  2020年   2篇
  2019年   1篇
  2018年   3篇
  2017年   3篇
  2016年   6篇
  2015年   22篇
  2014年   15篇
  2013年   19篇
  2012年   10篇
  2011年   9篇
  2010年   21篇
  2009年   11篇
  2008年   6篇
  2007年   6篇
  2006年   4篇
  2005年   6篇
  2004年   4篇
  2002年   1篇
  2001年   9篇
  2000年   2篇
  1999年   6篇
  1998年   20篇
  1997年   19篇
  1996年   29篇
  1995年   15篇
  1994年   22篇
  1993年   13篇
  1992年   4篇
  1991年   2篇
  1990年   5篇
  1989年   5篇
  1988年   14篇
  1987年   4篇
  1986年   6篇
  1985年   10篇
  1984年   5篇
  1983年   8篇
  1982年   3篇
  1981年   2篇
  1980年   3篇
  1979年   3篇
  1978年   1篇
  1977年   7篇
  1976年   4篇
  1975年   3篇
  1963年   1篇
  1961年   1篇
排序方式: 共有379条查询结果,搜索用时 15 毫秒
131.
132.

OBJECTIVES:

To assess outcomes of prenatally diagnosed tetralogy of Fallot and determine factors associated with the choice to undergo a valve-sparing repair versus transannular patch, and the use of prostaglandins at birth.

METHODS:

All cases at The Hospital for Sick Children (Toronto, Ontario) with a fetal diagnosis of tetralogy of Fallot from 1998 to 2006, were reviewed for demographic and fetal echocardiographic data to determine factors associated with the valve-sparing repair and need for perinatal support.

RESULTS:

Sixty-four fetuses met inclusion criteria (median gestational age 22 weeks) with 47 live births. Twenty-six underwent valve-sparing repair (median age 5.7 months) and 14 underwent transannular patch repair (median age 4.5 months). There were seven deaths before surgery and one post-transannular patch repair. One patient required a transannular patch repair after the initial valve-sparing repair. Twelve of 29 (41%) patients received prostaglandins at birth. Type of surgical repair, use of prostaglandins and postnatal death were among the outcomes investigated. The mean pulmonary valve (PV) z-score was −3.0±2.0 and the mean PV/aortic valve (AoV) ratio was 0.65±0.10. Lower PV z-score (P=0.04), smaller PV/AoV ratio (P=0.04) and the presence of nonantegrade arterial duct flow (P=0.02) were associated with prostaglandin use. A higher PV/AoV ratio was associated with valve-sparing repair (P=0.04). Fetal z-scores of the PV, AoV and right pulmonary artery at 29 to 32 weeks gestational age correlated with respective postnatal z-scores (P=0.01).

CONCLUSION:

Fetal echocardiographic variables were associated with the use of prostaglandins and valve-sparing repair in fetuses with tetralogy of Fallot, and at 29 weeks, correlated with postnatal valve diameters.  相似文献   
133.
Summary. Background and objectives: Thrombin activatable fibrinolysis inhibitor (TAFI) attenuates fibrinolysis and may therefore contribute to the pathophysiology of arterial thrombosis. The aim of the present study was to elucidate the pathogenetic role of TAFI levels and genotypes in young patients with arterial thrombosis. Patients and methods: In a case–control study, 327 young patients with a recent first‐ever event of coronary heart disease (CHD subgroup) or cerebrovascular disease (ischemic stroke subgroup) and 332 healthy young controls were included. TAFI levels [intact TAFI, activation peptide (TAFI‐AP) and (in)activated TAFI (TAFIa(i)] and TAFI activity were measured and genetic variations in the TAFI gene (?438G/A, 505G/A and 1040C/T) were determined. Results: In the total group of patients, TAFIa(i) levels were higher (145.1 ± 37.5%) than in controls (137.5 ± 31.3%, P = 0.02). Plasma levels of intact TAFI, TAFI‐AP and TAFI activity were similar in patients and controls. In the CHD subgroup (n = 218), intact TAFI levels were higher (109.4 ± 23.0%) than in controls (102.8 ± 20.7%, P = 0.02). In 325Ile/Ile homozygotes, lower TAFI levels and a decreased risk of arterial thrombosis were observed (OR 0.58, 95% CI 0.34–0.99) compared with patients with the common 325Thr/Thr genotype. This association was most evident in CHD patients (OR 0.48, 95% CI 0.26–0.90). Haplotype analyses supported a role for the Thr325Ile polymorphism. Conclusions: TAFIa(i) levels were higher in patients with cardiovascular disease. Furthermore, the TAFI 325Thr/Ile polymorphism was associated with lower TAFI levels and with the risk of cardiovascular disease in young patients, especially in CHD.  相似文献   
134.
To evaluate the separation efficiency of Ericsson's two- and three- layer albumin separation methods, semen samples from 21 healthy males were studied. Seven patients already had two or more sons, another seven had two or more daughters and the other seven had primary infertility due to female factors. The semen samples were divided into three aliquots: one remained unprocessed initially, the other two aliquots went through two- and three-layer albumin separation methods respectively. All samples were then stained with X-Y double staining probes. In each group, four or five samples were processed at room temperature, and two or three at body temperature (37 degrees C). The labelling efficiency of X-Y double staining probe was over 99%. The X:Y sperm ratios were even in the original samples. The ratios of the X and Y spermatozoa were altered slightly but significantly after the two- layer (P < or = 0.05) or the three-layer (P < or = 0.005) separation. The alterations occurred only at room temperature. The X spermatozoa increased and the Y spermatozoa decreased, both to a small degree of difference (1.4-3.5%). Double fluorescence in-situ hybridization analysis therefore showed that albumin separation methods do not enrich Y spermatozoa.   相似文献   
135.
Gay  JC; Stitt  ES 《Blood》1988,71(1):159-165
Platelet-activating factor (PAF) is a proinflammatory lipid that has both platelet- and phagocyte-stimulating properties. Because several known activators of calcium-, phospholipid-dependent protein kinase (protein kinase c, PKC) also stimulate neutrophil responses and because neutrophil stimuli such as phorbol diesters and the chemotactic peptide f-Met-Leu-Phe are reported to increase protein kinase activity in neutrophil (PMN) particulate fractions, we investigated the effect of PAF on neutrophil protein kinase activities. In neutrophils exposed to 10(-6) mol/L PAF, cytosolic PKC activity was 521 +/- 38 pmol 32P/10(7) PMN/min (mean +/- SEM), which was not significantly lower than cystolic activity in buffer-treated controls (558 +/- 32 pmol 32P/10(7) PMN/min, n = 14). PAF-exposed cells exhibited a concomitant rise in protein kinase activity associated with the particulate fraction with 53 +/- 4 pmol 32P/10(7) PMN/min compared with 32 +/- 2 pmol in control cells (n = 14). Particulate protein kinase activity was independent of the presence of calcium and phospholipid in the assay medium. The specific PKC inhibitor H-7 inhibited particulate protein kinase activity, however, which suggested that the enzyme activity assayed in this fraction may be PKC in a constitutively activated form. The increase in particulate protein kinase activity induced by PAF required the presence of cytochalasin B, was detectable within 5 seconds of exposure to PAF, and was not reversed by washing the cells free of extracellular PAF after initial exposure. Although PAF did not have a direct effect on PKC activity from cytosolic fractions from resting cells, the increase in particulate protein kinase activity induced by PAF was inhibited when the cells were first depleted of calcium by incubation with Quin 2. These results suggest that PAF induces an increase in particulate protein kinase activity in neutrophils by a calcium- dependent mechanism and that the induction of membrane-associated protein kinase activity may be involved in neutrophil-stimulating actions such as superoxide production, which occur at higher concentrations of PAF.  相似文献   
136.
Internal mammary lymph nodes are an important site of occult metastasis in clinically operable and recurrent breast carcinoma. Anatomic distribution of enlarged internal mammary nodes in patients with breast cancer was analyzed in a review of thoracic computed tomographic studies of 219 women with operable, advanced, or recurrent cancer. Enlarged nodes were observed in 45 patients (20.5%), 32 with unilateral and 13 with bilateral involvement. Mean nodal diameter was 1.95 cm (0.6-6.0 cm). Lymphadenopathy was limited to one anterior intercostal space in 43%, two spaces in 26%, three spaces in 22%, and four spaces in 9%. Solitary or dominant nodal enlargement was centered at the first space in 14%, second space in 60%, and third space in 26%. Isolated lymphadenopathy in the fourth or fifth spaces was not observed. Metastases to internal mammary nodes frequently occur at multiple levels and are most common in the second and third spaces. This finding concurs with current surgical practice when internal mammary nodes are sampled.  相似文献   
137.
Sixty-two Dutch patients with the diagnosis paranoid schizophrenia (SCH) were HLA-A-, -B- and -C-typed. An increase in the frequencies of A9 ( P = 0.02, relative risk 1.8) and B5 ( P = 0.04, relative risk 1.9) was found. Although these correlations do not remain significant after correction for the number of antigens tested, both findings confirm other data from the literature, including the first published report from a population in Sweden. From all hitherto published literature data, the combined relative risks for A9 and B5 is significantly increased. These data strongly indicate that the distribution of HLA antigens among SCH patients is different from the control population.  相似文献   
138.
Most patients with primary IgA nephropathy (IgAN) have a significantly higher memory repertoire of IgA1-producing B lymphocytes in their bone marrow together with high plasma levels of IgA1. The connection between the mucosal immune system and the bone marrow compartment is probably based on traffic of either antigen-presenting cells (APC) or antigen-specific lymphocytes. Cytokines play an important role in the proliferation and differentiation of lymphoid cells. In order to mimic the in vivo situation as much as possible, we assessed cytokine production profiles ex vivo in 23 IgAN patients and matched controls, using lipopolysaccharide (LPS)- or phytohaemagglutinin (PHA)-stimulated whole blood (WB) cultures. Interferon-gamma (IFN-γ), IL-2, IL-6, IL-10 and tumour necrosis factor-alpha (TNF-α) production in culture supernatants were determined by cytokine-specific ELISAs. Compared with controls, PHA-stimulated cultures resulted in significantly higher IL-10 (P < 0.001), IL-2 (P < 0.005) and IFN-γ (P < 0.001) levels in IgAN patients, but no significant differences in TNF-α or IL-6 levels were found. In LPS-stimulated cultures, the only significant difference (P < 0.001) between the two groups was the increased IL-10 production in IgAN patients. The enhanced cytokine production in stimulated WB cultures suggests altered monocyte-related T cell responses in patients with IgAN. Increased IL-10 production may eventually result in an increased number of IgA-producing B lymphocytes in the bone marrow. In addition, high levels of endogenous IL-10 may down-regulate the effector functions of monocytes, or possibly APC in general, and consequently the IgA response at the mucosal level.  相似文献   
139.
Background: The purpose of this study was to evaluate the effectiveness of directly integrating self‐monitoring blood glucose (BG) information with insulin pump therapy on overall glycemic control. Methods: In this randomized trial, 34 youth with type 1 diabetes using insulin pump therapy were trained on the use of the Deltec Cozmo® Insulin Pump. Seventeen were randomized to use the CoZmonitor® Blood Glucose Module, a device that attaches to the back of the pump using FreeStyle® technology to perform BG tests which read directly on the pump screen. The remaining 17 (control group) used a FreeStyle Flash meter, a stand‐alone BG meter, for their BG testing. At baseline, 3 and 6 months, the subjects filled out a questionnaire, had a hemoglobin A1c (HbA1c) test, and had pumps and meters downloaded. Results: After 3 months of study, there were no changes in mean HbA1c (± SD) values for the experimental (8.7 ± 1.1 to 8.6 ± 1.1) or the control groups (9.1 ± 1.4 to 9.2 ± 1.5). There were also no significant differences in HbA1c values after 6 months. The average number of BG tests per day did not change significantly in either group during the study. After 3 and 6 months, the experimental group rated satisfaction with the use of the CoZmonitor at 4.4 and 3.8 (respectively) on a five‐point Likert scale, with 5 being the most satisfied. Conclusions: Although significant changes in HbA1c values or the number of BG tests were not found, use of the BG module had a positive level of satisfaction.  相似文献   
140.
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