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   2120篇
  免费   166篇
  国内免费   6篇
耳鼻咽喉   8篇
儿科学   58篇
妇产科学   54篇
基础医学   338篇
口腔科学   21篇
临床医学   230篇
内科学   426篇
皮肤病学   54篇
神经病学   200篇
特种医学   48篇
外科学   153篇
综合类   12篇
一般理论   2篇
预防医学   253篇
眼科学   22篇
药学   241篇
中国医学   2篇
肿瘤学   170篇
  2023年   27篇
  2022年   54篇
  2021年   110篇
  2020年   69篇
  2019年   76篇
  2018年   92篇
  2017年   68篇
  2016年   62篇
  2015年   82篇
  2014年   89篇
  2013年   143篇
  2012年   188篇
  2011年   198篇
  2010年   96篇
  2009年   84篇
  2008年   105篇
  2007年   111篇
  2006年   119篇
  2005年   110篇
  2004年   94篇
  2003年   89篇
  2002年   61篇
  2001年   15篇
  2000年   6篇
  1999年   8篇
  1998年   13篇
  1997年   5篇
  1996年   5篇
  1995年   10篇
  1994年   3篇
  1992年   6篇
  1991年   10篇
  1990年   6篇
  1989年   3篇
  1987年   4篇
  1986年   3篇
  1985年   3篇
  1984年   3篇
  1983年   5篇
  1982年   3篇
  1981年   4篇
  1978年   5篇
  1971年   3篇
  1959年   2篇
  1954年   3篇
  1932年   2篇
  1930年   2篇
  1929年   2篇
  1927年   2篇
  1921年   2篇
排序方式: 共有2292条查询结果,搜索用时 15 毫秒
81.

Purpose

This study aims to identify whether selected patient and ward-related factors are associated with the use of coercive measures. Data were collected as part of the EUNOMIA international collaborative study on the use of coercive measures in ten European countries.

Methods

Involuntarily admitted patients (N = 2,027) were divided into two groups. The first group (N = 770) included patients that had been subject to at least one of these coercive measures during hospitalization: restraint, and/or seclusion, and/or forced medication; the other group (N = 1,257) included patients who had not received any coercive measure during hospitalization. To identify predictors of use of coercive measures, both patients’ sociodemographic and clinical characteristics and centre-related characteristics were tested in a multivariate logistic regression model, controlled for countries’ effect.

Results

The frequency of the use of coercive measures varied significantly across countries, being higher in Poland, Italy and Greece. Patients who received coercive measures were more frequently male and with a diagnosis of psychotic disorder (F20–F29). According to the regression model, patients with higher levels of psychotic and hostility symptoms, and of perceived coercion had a higher risk to be coerced at admission. Controlling for countries’ effect, the risk of being coerced was higher in Poland. Patients’ sociodemographic characteristics and ward-related factors were not identifying as possible predictors because they did not enter the model.

Conclusions

The use of coercive measures varied significantly in the participating countries. Clinical factors, such as high levels of psychotic symptoms and high levels of perceived coercion at admission were associated with the use of coercive measures, when controlling for countries’ effect. These factors should be taken into consideration by programs aimed at reducing the use of coercive measures in psychiatric wards.  相似文献   
82.
This paper provides up to date prevalence estimates of mental disorders in Germany derived from a national survey (German Health Interview and Examination Survey for Adults, Mental Health Module [DEGS1‐MH]). A nationally representative sample (N = 5318) of the adult (18–79) population was examined by clinically trained interviewers with a modified version of the Composite International Diagnostic Interview (DEGS‐CIDI) to assess symptoms, syndromes and diagnoses according to DSM‐IV‐TR (25 diagnoses covered). Of the participants 27.7% met criteria for at least one mental disorder during the past 12 months, among them 44% with more than one disorder and 22% with three or more diagnoses. Most frequent were anxiety (15.3%), mood (9.3%) and substance use disorders (5.7%). Overall rates for mental disorders were substantially higher in women (33% versus 22% in men), younger age group (18–34: 37% versus 20% in age group 65–79), when living without a partner (37% versus 26% with partnership) or with low (38%) versus high socio‐economic status (22%). High degree of urbanization (> 500,000 inhabitants versus < 20,000) was associated with elevated rates of psychotic (5.2% versus 2.5%) and mood disorders (13.9% versus 7.8%). The findings confirm that almost one third of the general population is affected by mental disorders and inform about subsets in the population who are particularly affected. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   
83.
The intestinal epithelium is perpetually renewed from a stem cell niche in the base of crypts to maintain a healthy bowel mucosa. Exit from this niche and maturation of epithelial cells requires tightly controlled gradients in BMP signalling, progressing from low BMP signalling at the crypt base to high signalling at the luminal surface. The BMP antagonist gremlin 1 (Grem1) is highly expressed by subepithelial myofibroblasts adjacent to the intestinal crypts but its role in regulating the stem cell niche and epithelial renewal in vivo has not been explored. To explore the effects of Grem1 loss in adulthood following normal growth and development, we bred mice (ROSA26CreER-Grem1 flx/flx) in which Grem1 could be deleted by tamoxifen administration. While Grem1 remained intact, these mice were healthy, grew normally, and reproduced successfully. Following Grem1 depletion, the mice became unwell and were euthanised (at 7–13 days). Post-mortem examination revealed extensive mucosal abnormalities throughout the small and large intestines with failure of epithelial cell replication and maturation, villous atrophy, and features of malabsorption. Bone marrow hypoplasia was also observed with associated early haematopoietic failure. These results demonstrate an essential homeostatic role for gremlin 1 in maintaining normal bowel epithelial function in adulthood, suggesting that abnormalities in gremlin 1 expression can contribute to enteropathies. We also identified a previously unsuspected requirement for gremlin 1 in normal haematopoiesis. © 2020 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.  相似文献   
84.
85.
86.
87.
Alterations in the genome that lead to changes in DNA sequence copy number are characteristic features of solid tumors. We used CGH+SNP microarray and HPV-FISH techniques for detailed screening of copy number alterations (CNAs) in a cohort of 26 patients with cervical carcinoma (CC). This approach identified CNAs in 96.2% (25/26) of tumors. Array-CGH discovered CNAs in 73.1% (19/26) of samples, HPV-FISH experiments revealed CNAs in additional 23.1% (6/26) of samples. Common gains of genetic sequences were observed in 3q (50.0%), 1q (42.4%), 19q (23.1%), while losses were frequently found in 11q (30.8%), 4q (23.1%) and 13q (19.2%). Chromosomal regions involved in loss of heterozygosity were observed in 15.4% of samples in 8q21, 11q23, 14q21 and 18q12.2. Incidence of gain 3q was associated with HPV 16 and HPV 18 positive samples and simultaneous presence of gain 1q (P = 0.033). We did not found a correlation between incidence of CNAs identified by array-CGH and HPV strain infection and incidence of lymph node metastases. Subsequently, HPV-FISH was used for validation of array-CGH results in 23 patients for incidence of hTERC (3q26) and MYC (8q24) amplification. Using HPV-FISH, we found chromosomal lesions of hTERC in 87.0% and MYC in 65.2% of specimens. Our findings confirmed the important role of HPV infection and specific genomic alterations in the development of invasive cervical cancer. This study also indicates that CGH+SNP microarrays allow detecting genome-wide CNAs and copy-neutral loss of heterozygosity more precisely, however, it may be less sensitive than FISH in samples with low level clonal CNAs.  相似文献   
88.
This article is focused on the comparison of the reliability of the results obtained by image analysis (newly proposed evaluation method) with well-known methods of evaluation of long-term corrosion resistance of glass fibers in an alkaline environment (pH > 12). The developed method is based on the analysis of scanning electron microscopy images (diameter and structures on the fiber surface). An experiment (52 weeks) was performed to evaluate two types of glass fibers: anticorrosive glass fibers (ARGFs) and E-glass fibers (EGFs). Three media were used to treat the fibers (23 ± 2 °C): H2O, Ca(OH)2, and K2SiO3. The ARGFs’ tensile strength did not reduce; a decrease by 68% was observed for EGFs in H2O. Tensile strength decreased by 32% and 85–95% in K2SiO3; by 50% and 64% in Ca(OH)2 for the ARGF and EGF, respectively. Statistical analysis was performed to validate the reliability and plausibility of the developed method. ARGFs and EGFs did not show any relationship between the fiber diameter and weight in H2O; however, the linear trends may predict this relationship in Ca(OH)2 and K2SiO3. For the ARGF and EGF, the cubic trend was suitable for predicting the change in fiber weight and diameter over time in Ca(OH)2 and K2SiO3.  相似文献   
89.
Background: High hydrostatic pressure (HHP) processing is a non-thermal method proposed as an alternative to Holder pasteurization (HoP) for the sterilization of human breast milk (BM). HHP preserves numerous milk bioactive factors that are degraded by HoP, but no data are available for milk apelin and glucagon-like peptide 1 (GLP-1), two hormones implicated in the control of glucose metabolism directly and via the gut–brain axis. This study aims to determine the effects of HoP and HHP processing on apelin and GLP-1 concentrations in BM and to test the effect of oral treatments with HoP- and HHP-BM on intestinal contractions and glucose metabolism in adult mice. Methods: Mice were treated by daily oral gavages with HoP- or HHP-BM during one week before intestinal contractions, and glucose tolerance was assessed. mRNA expression of enteric neuronal enzymes known to control intestinal contraction was measured. Results: HoP-BM displayed a reduced concentration of apelin and GLP-1, whereas HHP processing preserved these hormones close to their initial levels in raw milk. Chronic HHP-BM administration to mice increased ileal mRNA nNos expression level leading to a decrease in gut contraction associated with improved glucose tolerance. Conclusion: In comparison to HoP, HPP processing of BM preserves both apelin and GLP-1 and improves glucose tolerance by acting on gut contractions. This study reinforces previous findings demonstrating that HHP processing provides BM with a higher biological value than BM treated by HoP.  相似文献   
90.
In parallel with increasing Ni production and utilisation, Ni pollution in the soil–water continuum has become an alarming and global problem. Solutions for removing Ni from industrial effluents have been widely investigated and biosorption has emerged as an efficient, cost-effective, scalable and sustainable alternative for water treatment. However, the biosorption capacity is limited by the chemical composition of the biomaterial and the Ni-enriched biomaterials are rarely valorised. In this work, the biosorption capacity of three abundant biomaterials with different chemical properties – water hyacinth, coffee grounds and pinecones – was studied before and after functionalization, and reached a maximum biosorption capacity of 51 mg g−1 of Ni(ii). A bioinspired functionalization approach was investigated introducing carboxylate moieties and was conducted in green conditions. The Ni-enriched biomaterials were valorised by transformation into catalysts, which were characterised by MP-AES and XRPD. Their characterisation revealed a structure similar to nickel formate, and hence the Eco-Ni(HCOO)2 catalysts were tested in Suzuki–Miyaura reactions. Several aryl iodides were successfully cross-coupled to phenylboronic acids using Eco-Ni(HCOO)2 without any ligand, a mild and green base in a mixture of green solvents.

New biomaterials were functionalised for biosorption of Ni from aqueous solutions and valorised as ecocatalysts in Suzuki–Miyaura green reactions.  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