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   5913篇
  免费   460篇
  国内免费   32篇
耳鼻咽喉   51篇
儿科学   161篇
妇产科学   139篇
基础医学   913篇
口腔科学   186篇
临床医学   445篇
内科学   1344篇
皮肤病学   142篇
神经病学   785篇
特种医学   136篇
外科学   533篇
综合类   7篇
一般理论   1篇
预防医学   418篇
眼科学   74篇
药学   514篇
中国医学   15篇
肿瘤学   541篇
  2024年   10篇
  2023年   52篇
  2022年   141篇
  2021年   266篇
  2020年   157篇
  2019年   229篇
  2018年   241篇
  2017年   149篇
  2016年   212篇
  2015年   236篇
  2014年   288篇
  2013年   356篇
  2012年   538篇
  2011年   498篇
  2010年   278篇
  2009年   236篇
  2008年   352篇
  2007年   362篇
  2006年   368篇
  2005年   270篇
  2004年   293篇
  2003年   226篇
  2002年   198篇
  2001年   50篇
  2000年   41篇
  1999年   58篇
  1998年   49篇
  1997年   32篇
  1996年   25篇
  1995年   21篇
  1994年   17篇
  1993年   12篇
  1992年   28篇
  1991年   18篇
  1990年   14篇
  1989年   13篇
  1988年   9篇
  1987年   14篇
  1986年   3篇
  1985年   3篇
  1984年   10篇
  1982年   3篇
  1981年   3篇
  1980年   3篇
  1979年   6篇
  1978年   3篇
  1976年   3篇
  1975年   3篇
  1969年   2篇
  1921年   1篇
排序方式: 共有6405条查询结果,搜索用时 437 毫秒
101.
Non-myeloablative stem cell transplantation (NMT) has been increasingly used in compromised patients who would otherwise have been unable to undergo allotransplant. There is little understanding of the kinetics of immune reconstitution and its influence on infective complications following NMT. The aim of present study was to evaluate lymphocyte subset reconstitution over the first 12 months post-transplant in 15 adult patients receiving NMT with comparison to that of 30 patients grafted with a conventional hemopoietic stem cell transplantation (HSCT). NMT recipients were conditioned with fludarabine-based conditioning regimens. Peripheral blood stem cell (PBSC) was the source of stem cells in 13 NMT recipients and in 24 conventional HSCT recipients. Absolute numbers of helper (CD4+) T cells, naive (CD4+ CD45RA+) and memory (CD4+ CD45RO+) T cells as well as suppressor (CD8+) T cells, CD19+ B cells and NK cells were comparable in the two groups at all time points after transplantation. A median value of 200 CD4+ T cells/microl was achieved at 2 months post-transplant by the NMT and HSCT recipients. The CD4:CD8 ratio remained severely depressed throughout the study period. Almost all CD4+ lymphocytes expressed CD45RO antigen in the both groups of patients B lymphocytes showed low counts throughout the entire study period in both groups. Bacteremia and CMV antigenemia occurred respectively in 13 and 36% of the patients in the NMT group and in 15 and 39% of the patients in the HSCT group. Our preliminary data indicate that patients receiving a NMT have a lymphocyte reconstitution similar to that observed in patients who received a conventional HSCT. The incidence of bacteremia and CMV infection were not significantly different between the groups. Nevertheless, due to the small sample size, these results should be considered suggestive rather than definitive.  相似文献   
102.
Digestive Diseases and Sciences - Deregulation of immune response and oxidative stress contribute to nonalcoholic fatty liver disease (NAFLD) pathogenesis. Resistin is a physiological modulator of...  相似文献   
103.
Although surgery alone represents a curative approach for patients with pT3N0M0 colon cancer, about 15–20 % of these patients develop a relapse of disease. Microsatellite instability (MSI) is one of the most important molecular markers in colorectal cancer. The aim of this study was to investigate the prognostic relevance of MSI in all pT3N0M0 tumors recorded in the Cancer Registry of the Province of Modena—(Northern Italy) within the 2002–2006 period in patients who showed a relapse of disease during the 5-year period of follow-up (59 cases). They were compared to 59 controls similar in clinical and pathological features but with good prognosis. None of the subjects received adjuvant chemotherapy. MSI status was tested using BAT25, BAT26, NR24, and CAT25 fluorescent-labeled mononucleotide markers. The overall prevalence of MSI was 12.7 % (15 of 118 cases). MSI was detected mainly in mucinous adenocarcinoma (p < 0.003), in high-grade tumors (p < 0.008), in right-sided neoplasms (p < 0.005), and in patients with a better prognosis, though the difference was not statistically significant (11/59 patients ?18.6 % vs 4/59 patients ?6.7 %; OR 0.36 CI 95 % 0.11–1.15; p = 0.08). However, in multivariate analysis, MSI status becomes the strongest independent factor associated with relapse (OR 0.21, CI 95 % 0.06–0.81; p = 0.023), together with mucinous histological type (OR 0.40, CI 90 % 0.18–0.92). MSI is a relevant prognostic factor in stage pT3N0M0 colon cancer suitable to discriminate those patients with a high risk of relapse.  相似文献   
104.
The silent beta-thalassemia mutation, beta(+)-101C-->T, is the only mutation currently described in the distal beta-globin CACCC box. We present a novel mutation, a C-->G transversion, in the same position. Expression analysis in heterozygous subjects demonstrated that the mutation determines a 20% reduction in the output of the beta-globin gene. DNA-protein interaction and transactivation analysis correlated the decrease in the beta-globin synthesis with the reduced binding and transactivation of EKLF to the mutant promoter. These data predict that the beta-101C-->G mutation will display a silent thalassemia phenotype similar to that of the beta-101C-->T mutation.  相似文献   
105.
E Levi  G Z Fadda  C Ozbasli  S G Massry 《Endocrinology》1992,131(5):2182-2188
Phosphate depletion (PD) causes a rise in basal level of cytosolic calcium ([Ca2+]i) of pancreatic islets, a decrease in their basal and stimulated ATP content, a reduction in the maximum velocity (Vmax) of Ca2+ adenosine triphosphatase (ATPase) and Na(+)-K+ ATPase, impaired glucose-induced calcium signal and decreased glucose-induced insulin secretion. The sequence of events that lead to these derangements during the evolution of PD are not defined. The present study examined this issue by measuring the metabolic and functional profile of pancreatic islets weekly during the evolution of PD over a period of 6 weeks, and whether phosphate repletion reverses these abnormalities. The results show that initial abnormalities are a rise in Vmax of Ca2+ ATPase and modest rise in basal [Ca2+]i. This was followed by a fall in basal and stimulated ATP content. With the fall in ATP content, the Vmax of Ca2+ ATPase and Na(+)-K+ ATPase decreases and the rise in [Ca2+]i becomes more pronounced. A decrease in glucose-induced insulin secretion becomes evident with the fall in ATP, the decrease in glucose-induced calcium signal, and/or delta[Ca2+]i/basal[Ca2+]i. All functional and metabolic derangements of the pancreatic islets returned to normal after phosphate repletion. Taken together, our data are consistent with the notion that PD is associated with an initial increase in calcium influx into the islets. This is followed by modest but significant rise in [Ca2+]i which, in turn, would inhibit mitochondrial oxidation and ATP generation leading to a decrease in ATP content. The latter compromises the activity of Ca2+ ATPase and Na(+)-K+ ATPase which are involved, directly or indirectly, in calcium extrusion out of the islets. The increased influx of calcium combined with decreased calcium extrusion is followed by a further rise in basal levels of [Ca2+]i. This sequence of events continues until a steady state is reached and is characterized by reduced basal and stimulated ATP content, reduced Vmax of Ca2+ ATPase and Na(+)-K+ ATPase and elevated basal level of [Ca2+]i. Phosphate repletion reverses all these abnormalities.  相似文献   
106.

Introduction

The incidence of left ventricular (LV) thrombus formation in ST-segment elevation myocardial infarction (STEMI) patients in the current era of primary percutaneous coronary intervention (PCI) is not well established. We performed a meta-analysis to assess the actual incidence and predictors of LV thrombus by cardiovascular magnetic resonance (CMR) in STEMI treated by primary PCI.

Methods

We searched MEDLINE and EMBASE databases up to February 2018. We included all studies published as a full-text article, reporting the incidence of LV thrombus by CMR within 1 month following acute STEMI in patients treated by primary PCI. A binary random-effects model was used to estimate the pooled incidence of LV thrombus. The diagnostic performance of transthoracic echocardiography (TTE) as compared with CMR was pooled to obtain the sensitivity and specificity of TTE with CMR as the gold standard. Embolic and bleeding complications of LV thrombus were also evaluated.

Results

Ten studies were included in the meta-analysis. The incidence of LV thrombus by CMR in all-comer STEMI patients (n?=?2072) was 6.3% with 96% of LV thrombus occurring in those with anterior STEMI (12.2% incidence). When only anterior STEMI with LVEF<?50% were considered (n?=?447), the incidence of LV thrombus was 19.2%. Compared with CMR, the sensitivity of TTE to detect LV thrombus was 29% with a specificity of 98%. The sensitivity of TTE increased to 70% in those with anterior STEMI and reduced LVEF. LV thrombus resolved in 88% of cases by 3 to 6 months. After 1–2 years follow-up, the embolic complication rate was similar at 1.5% (P?=?0.25) but the bleeding complication rate was significantly higher (8.8% versus 0.5%, P?<?0.001) in the LV thrombus group on triple therapy when compared to the no LV thrombus group on dual antiplatelet therapy.

Conclusion

In the primary PCI era, CMR detection of an LV thrombus post-STEMI remains high with incidence of nearly 20% in anterior STEMI with depressed LVEF. Patients with LV thrombus treated by triple therapy had similar embolic complications but higher bleeding complications than those with no LV thrombus treated with dual antiplatelet therapy. A 3 month follow-up CMR scan to guide anticoagulation duration might help mitigate bleeding risk.
  相似文献   
107.
108.
109.

OBJECTIVE:

to analyze the socio-familial and community inclusion and social participation of people with disabilities, as well as their inclusion in occupations in daily life.

METHOD:

qualitative study with data collected through open interviews concerning the participants'' life histories and systematic observation. The sample was composed of ten individuals with acquired or congenital disabilities living in the region covered by a Family Health Center. The social conception of disability was the theoretical framework used. Data were analyzed according to an interpretative reconstructive approach based on Habermas'' Theory of Communicative Action.

RESULTS:

the results show that the socio-familial and community inclusion of the study participants is conditioned to the social determinants of health and present high levels of social inequality expressed by difficult access to PHC and rehabilitation services, work and income, education, culture, transportation and social participation.

CONCLUSION:

there is a need to develop community-centered care programs in cooperation with PHC services aiming to cope with poverty and improve social inclusion.  相似文献   
110.
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