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   3374篇
  免费   249篇
  国内免费   15篇
耳鼻咽喉   25篇
儿科学   130篇
妇产科学   94篇
基础医学   544篇
口腔科学   38篇
临床医学   285篇
内科学   806篇
皮肤病学   81篇
神经病学   397篇
特种医学   119篇
外科学   336篇
综合类   12篇
一般理论   1篇
预防医学   205篇
眼科学   23篇
药学   228篇
中国医学   5篇
肿瘤学   309篇
  2024年   4篇
  2023年   40篇
  2022年   88篇
  2021年   146篇
  2020年   102篇
  2019年   124篇
  2018年   112篇
  2017年   98篇
  2016年   110篇
  2015年   125篇
  2014年   172篇
  2013年   195篇
  2012年   307篇
  2011年   309篇
  2010年   155篇
  2009年   147篇
  2008年   264篇
  2007年   209篇
  2006年   178篇
  2005年   188篇
  2004年   138篇
  2003年   119篇
  2002年   88篇
  2001年   19篇
  2000年   21篇
  1999年   21篇
  1998年   19篇
  1997年   17篇
  1996年   23篇
  1995年   9篇
  1994年   6篇
  1993年   9篇
  1992年   10篇
  1991年   8篇
  1990年   4篇
  1989年   3篇
  1988年   11篇
  1986年   10篇
  1985年   5篇
  1984年   8篇
  1983年   1篇
  1980年   3篇
  1979年   1篇
  1975年   1篇
  1974年   2篇
  1972年   1篇
  1971年   2篇
  1970年   2篇
  1967年   1篇
  1966年   2篇
排序方式: 共有3638条查询结果,搜索用时 109 毫秒
61.
Electrochemotherapy (ECT) is a novel treatment for recurrent or in-transit unresectable melanoma metastases based on the administration of anti-neoplastic drugs followed by cancer cell electroporation. Whether ECT can also induce anti-tumour immunity is unclear. We addressed this issue investigating the presence of dendritic cells (DCs) in the inflammatory infiltrate of ECT-treated lesions. Biopsies from melanoma patients (n = 9) were taken before ECT (T0), at d7 and d14 after treatment and studied by immunofluorescence with DCs-related antibodies. Epidermal Langerin+ Langerhans cells (LCs) were the most represented subset before treatment. ECT induced a significant reduction in epidermal LCs number at d7 (p < 0.001), while they were completely replaced at d14. Similarly, the few LCs observed intermingled with metastatic melanoma cells at T0 decreased after treatment (p < 0.001), suggesting an ECT-induced activation of LCs. Consistently, at d1 after ECT (n = 3 patients), LCs were found to express CCR7, which mediates LCs migration to regional lymph nodes, and CD83, the typical DCs maturation marker. In contrast, plasmacytoid DCs (pDCs) were not present at T0, but significantly increased after ECT both in melanoma metastasis (p < 0.001) and perilesionally (p < 0.05). Similarly, CD1c+ dermal DCs (dDCs), observed in low number before ECT, strongly increased at d7 and even more at d14 (p < 0.05 and p < 0.001, respectively). Notably, some dDCs expressed CD83. These data suggest that ECT promotes LCs migration from the tumour to draining lymph nodes and pDCs and dDCs recruitment at the site of the lesion. These findings may help to design new strategies of in situ DCs vaccination in cancer patients.  相似文献   
62.
ObjectiveTo update the Spanish Society of Neurology's guidelines for stroke prevention in patients with type 2 diabetes or prediabetes, analysing the available evidence on the effect of metabolic control and the potential benefit of antidiabetic drugs with known vascular benefits in addition to conventional antidiabetic treatments in stroke prevention.DevelopmentPICO-type questions (Patient, Intervention, Comparison, Outcome) were developed to identify practical issues in the management of stroke patients and to establish specific recommendations for each of them. Subsequently, we conducted systematic reviews of the PubMed database and selected those randomised clinical trials evaluating stroke as an independent variable (primary or secondary). Finally, for each of the PICO questions we developed a meta-analysis to support the final recommendations.ConclusionsWhile there is no evidence that metabolic control reduces the risk of stroke, some families of antidiabetic drugs with vascular benefits have been shown to reduce these effects when added to conventional treatments, both in the field of primary prevention in patients presenting type 2 diabetes and high vascular risk or established atherosclerosis (GLP-1 agonists) and in secondary stroke prevention in patients with type 2 diabetes or prediabetes (pioglitazone).  相似文献   
63.
ObjectivesA seroprevalence study of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was conducted in a high-incidence area located in northeastern Italy.MethodsAll citizens above 10 years of age resident in five municipalities of the Autonomous Province of Trento, with the highest incidence of coronavirus disease 2019 (COVID-19) cases, were invited to participate in the study. Among 6098 participants, 6075 sera and a standardized questionnaire administered face-to-face were collected between 5 May and 15 May 2020 and examined. Symptomatic individuals and their family contacts were tested by RT-PCR. Anti-SARS-CoV-2 antibodies were detected using an Abbott SARS-CoV-2 IgG assay, which was performed on the Abbott Architect i2000SR automated analyser. Seroprevalence was calculated as the proportion of positive results among the total number tested. A multivariable logistic regression model was performed to assess the relationship between seropositive versus seronegative individuals for a set of explanatory variables.ResultsA total of 1402 participants were positive for IgG antibodies against SARS-CoV-2, with a prevalence of 23.1% (1402/6075). The highest prevalence was found in the age class 40–49 years. Overall, 34.4% (2096/6098) of the participants reported at least one symptom. The ratio between reported cases identified by molecular test and those with seropositive results was 1:3, with a maximum ratio of about 1:7 in the age group <20 years and a minimum around 1:1 in those >70 years old. The infection fatality rate was 2.5% (35/1402). Among the symptoms, anosmia and ageusia were strongly associated with seropositivity.ConclusionsThe estimated seroprevalence of 23% was three-fold higher than the number of cases reported in the COVID-19 Integrated Surveillance data in the study area. This may be explained in part by a relatively high number of individuals presenting mild or no illness, especially those of younger age, and people who did not seek medical care or testing, but who may contribute to virus transmission in the community.  相似文献   
64.
Nasal turbinals, delicate and complex bones of the nasal cavity that support respiratory or olfactory mucosa (OM), are now easily studied using high resolution micro-computed tomography (μ-CT). Standard μ-CT currently lacks the capacity to identify OM or other mucosa types without additional radio-opaque staining techniques. However, even unstained mucosa is more radio-opaque than air, and thus mucosal thickness can be discerned. Here, we assess mucosal thickness of the nasal fossa using the cranium of a cadaveric adult dog that was μ-CT scanned with an isotropic resolution of 30 μm, and subsequently histologically sectioned and stained. After co-alignment of μ-CT slice planes to that of histology, mucosal thickness was estimated at four locations. Results based on either μ-CT or histology indicate olfactory mucosa is thicker on average compared with non-olfactory mucosa (non-OM). In addition, olfactory mucosa has a lesser degree of variability than the non-OM. Variability in the latter appears to relate mostly to the varying degree of vascularity of the lamina propria. Because of this, in structures with both specialized vascular respiratory mucosa and OM, such as the first ethmoturbinal (ET I), the range of thickness of OM and non-OM may overlap. Future work should assess the utility of diffusible iodine-based contrast enhanced CT techniques, which can differentiate epithelium from the lamina propria, to enhance our ability to differentiate mucosa types on more rostral ethmoturbinals. This is especially critical for structures such as ET I, which have mixed functional roles in many mammals.  相似文献   
65.
66.
67.
BackgroundPressure injuries (PIs) are a patient safety issue that impact patient outcomes. Intensive care unit (ICU) patients are at high risk of PIs.ObjectivesTo report the prevalence and classification of documented PIs in adult ICU patients, the use of pressure injury risk assessment tools, and support surface management as a part of the prevention of PIs.MethodsThis was a prospective, single-day, multicentre, cross-sectional study of patients aged ≥ 16 years admitted to adult ICUs in Australia and New Zealand (ANZ), August 2016 as part of the Australian and New Zealand Intensive Care Society Clinical Trials Group (ANZICS-CTG) Point Prevalence Program.FindingsData were collected on 671 patients (58% male) in 47 ICUs. The mean [standard deviation] age and weight were 60.2 years [17.2 years] and 82.1 kg [29.7 kg], respectively, with a severity of illness score (Acute Physiology and Chronic Health Evaluation [APACHE] II) of 18.2 [8.4]. PIs were reported in 10% (70/671) of patients. Patients with a PI had a mean APACHE II score of 22.5 [standard deviation; 7.7], and 57.1% (40/70) met the criteria for sepsis on the study day. There were 107 PIs documented on the study day (N = 107) in the 70 patients with nearly half of PIs present on ICU admission (46.7%; 50/107). The sacrum was the most common location for PIs (28.9%; 31/107) and then the heels (15.9%; 17/107). All units routinely use a risk of PI assessment tool and were cared for on an active or reactive support surface. Patients with a PI were more often moved to an active support surface.ConclusionsThe prevalence rate was reported at 10% for PIs for adult intensive care patients on the study day. More than half of the patients with a PI had signs of sepsis on the study day and a higher severity of illness, and more were cared for on active support surfaces. Most PIs were located at the sacrum and then the heels. All clinical sites routinely used a PI risk assessment tool.  相似文献   
68.
69.
70.
Giant cell tumor of bone (GCTb) represents 5% of bone tumors, and although considered benign, 5% metastasize to the lung. The expression of proteins directly or indirectly associated with osteolysis and tumor growth was studied on 163 samples of GCTb. Of these, 33 patients developed lung metastasis during follow‐up. The impact of tumor–host interaction on clinical aspects was evaluated with the aim of finding specific markers for new biological therapies, thus improving clinical management of GCTb. Protein expression was evaluated by immunohistochemical analysis on Tissue Microarray. The majority of GCTb samples from patients with metastatic disease were strongly positive to RANKL and its receptor RANK as well as to CAII and MMP‐2 and to pro‐survival proteins NFIB and c‐Fos. Kaplan–Meier analysis indicated a significant difference in metastasis free survival curves based on protein staining. Interestingly, the statistical correlation established a strong association between all variables studied with a higher τ coefficient for RANK/RANKL, RANK/NFIB, and RANKL/NFIB pairs. At multivariate analysis co‐overexpression of NFIB, RANK and RANKL significantly increased the risk of metastasis with an odds ratio of 13.59 (95%CI 4.12–44.82; p < 0.0005). In conclusion, the interconnection between matrix remodeling and tumor cell activity may identify tumor–host endpoints for new biological treatments. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 33:1205–1211, 2015.  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