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   5832篇
  免费   297篇
  国内免费   21篇
耳鼻咽喉   77篇
儿科学   228篇
妇产科学   175篇
基础医学   682篇
口腔科学   127篇
临床医学   402篇
内科学   1133篇
皮肤病学   137篇
神经病学   325篇
特种医学   108篇
外科学   1031篇
综合类   185篇
一般理论   3篇
预防医学   499篇
眼科学   185篇
药学   527篇
中国医学   34篇
肿瘤学   292篇
  2023年   58篇
  2022年   141篇
  2021年   253篇
  2020年   161篇
  2019年   190篇
  2018年   231篇
  2017年   148篇
  2016年   186篇
  2015年   198篇
  2014年   228篇
  2013年   302篇
  2012年   478篇
  2011年   456篇
  2010年   261篇
  2009年   189篇
  2008年   289篇
  2007年   276篇
  2006年   260篇
  2005年   263篇
  2004年   219篇
  2003年   208篇
  2002年   200篇
  2001年   82篇
  2000年   73篇
  1999年   70篇
  1998年   40篇
  1997年   26篇
  1996年   18篇
  1995年   25篇
  1994年   19篇
  1993年   24篇
  1992年   48篇
  1991年   40篇
  1990年   34篇
  1989年   37篇
  1988年   40篇
  1987年   25篇
  1986年   28篇
  1985年   29篇
  1984年   36篇
  1983年   25篇
  1982年   16篇
  1981年   22篇
  1980年   26篇
  1979年   9篇
  1977年   16篇
  1976年   19篇
  1972年   10篇
  1966年   10篇
  1931年   8篇
排序方式: 共有6150条查询结果,搜索用时 15 毫秒
121.
Metabolic Brain Disease - We report the potential role of 1H Nuclear Magnetic Resonance (NMR) based metabolomics in tuberculous meningitis (TBM). We also correlate the significant metabolites with...  相似文献   
122.
The aim of this study was to evaluate the use of different fixatives on the reliability of histopathological changes in a rabbit model of proliferative vitreoretinopathy (PVR). Twenty eyes from 10 rabbits were divided into four groups. The right eyes were used in two experimental groups (each n = 5), and the left, in two control groups (each n = 5). Using a newly developed scleral incision marker, an oblique scleral incision was standardized in the experimental groups, followed by intravitreal injection of 0.4 ml autologous blood and the left for wound repair for four weeks. Eyes were enucleated at four weeks. The groups differed in the type of used fixative solution (formaldehyde 4% vs. 1% buffered formaldehyde and 1.25% glutaraldehyde). The eyes were evaluated for the development of fibrosis, retinal detachment (RD), and processed for histopathology. Fibrous ingrowth of a variable degree was present in the experimental groups originating from the trauma site. Experimental eyes fixed with formaldehyde 4% had RD extension that was greater than that fixed in formaldehyde/glutaraldehyde mixture; however, the difference did not reach statistical significance (P = 0.15). This difference was not fully explained by the fibrosis which developed. In addition, in control groups, formaldehyde 4% induced a fixative-dependent retinal separation that was absent in eyes fixed with formaldehyde/glutaraldehyde mixture (P = 0.03). In conclusion, a mixture of buffered formaldehyde 1% and glutaraldehyde 1.25% combined with standardized scleral incision resulted in consistent pathological changes. A reliable PVR model is a condition sine qua non to evaluate antifibrotic treatment strategies.  相似文献   
123.
Loss-of-function variants in ANKRD11 were identified as the cause of KBG syndrome, an autosomal dominant syndrome with specific dental, neurobehavioural, craniofacial and skeletal anomalies. We present the largest cohort of KBG syndrome cases confirmed by ANKRD11 variants reported so far, consisting of 20 patients from 13 families. Sixteen patients were molecularly diagnosed by Sanger sequencing of ANKRD11, one familial case and three sporadic patients were diagnosed through whole-exome sequencing and one patient was identified through genomewide array analysis. All patients were evaluated by a clinical geneticist. Detailed orofacial phenotyping, including orthodontic evaluation, intra-oral photographs and orthopantomograms, was performed in 10 patients and revealed besides the hallmark feature of macrodontia of central upper incisors, several additional dental anomalies as oligodontia, talon cusps and macrodontia of other teeth. Three-dimensional (3D) stereophotogrammetry was performed in 14 patients and 3D analysis of patients compared with controls showed consistent facial dysmorphisms comprising a bulbous nasal tip, upturned nose with a broad base and a round or triangular face. Many patients exhibited neurobehavioural problems, such as autism spectrum disorder or hyperactivity. One-third of patients presented with (conductive) hearing loss. Congenital heart defects, velopharyngeal insufficiency and hip anomalies were less frequent. On the basis of our observations, we recommend cardiac assessment in children and regular hearing tests in all individuals with a molecular diagnosis of KBG syndrome. As ANKRD11 is a relatively common gene in which sequence variants have been identified in individuals with neurodevelopmental disorders, it seems an important contributor to the aetiology of both sporadic and familial cases.  相似文献   
124.
A phase 1 diagnostic study was performed to evaluate a novel technology for clinical proteomic research based on capillary electrophoresis and mass spectrometry. Urine from 40 patients after hematopoietic stem cell transplantation (HSCT; 35 allogeneic, 5 autologous) and 5 patients with sepsis was collected for a period of 100 days and analyzed. More than 1000 different polypeptides could be detected in individual samples. Polypeptide patterns excreted in the urine of patients were significantly different from those of healthy volunteers. No significant differences were detected comparing different conditioning regimens. The aim of this study was to identify polypeptide patterns functioning as early indicators of graft-versus-host disease (GVHD). Eighteen patients developed GVHD after allogeneic HSCT. Sixteen differentially excreted polypeptides formed a pattern of early GVHD markers, allowing discrimination of GVHD from patients without complications with 82% specificity and 100% sensitivity, cross-validated. Inclusion of 13 sepsis-specific polypeptides allowed us to distinguish sepsis from GVHD with a specificity of 97% and a sensitivity of 100%. Sequencing 2 prominent GVHD-indicative polypeptides led to the identification of a peptide from leukotriene A4 hydrolase and a peptide from serum albumin. The data reveal that capillary electrophoresis and mass spectrometry allow identification of biomarkers for a variety of diseases or related complications.  相似文献   
125.

Purpose

The adequate perioperative antibiotic prophylaxis in maxillofacial surgery is still under discussion due to the wide range of hard and soft tissue procedures as well as contaminated, semi-contaminated and clean surgical sides. Perioperative antibiosis is an easy applicable tool that can be used to decrease nosocomial morbidity and mortality by reducing the rate of infections. We compared strictly perioperative antibiosis with an extended postoperative prophylactic antibiosis.

Materials and methods

In this study, 901 consecutive patients, from a tertiary care maxillofacial surgery department were included and distributed into two groups: The first group received peri- and postoperative antibiotic prophylaxis (PP; n = 365) from the day of operation until the fifth day postoperatively. The second group was treated with single shot prophylaxis with intraoperative repetition as needed (SSP; n = 536) only. Furthermore, the patients were grouped according to their main diagnosis and surgical procedure. For comparison, general anamnestic data, cultured bacteria and resistances, number of surgical site infections and duration of hospitalization were compared.

Results

There were no statistically significant differences in general diseases or extent of surgery between the groups. There was no statistical difference in the surgical site infections between the groups regardless of their diagnosis. There were significant correlations between tracheotomised patients (p < 0.001) as well as patients with a higher BMI (p = 0.009) and the incidence of surgical site infections. Most common cultured bacteria were staphylococci.

Conclusion

Based on the findings of the study, we believe that a perioperative antibiosis delivers a sufficient prophylaxis for patients undergoing maxillofacial surgery procedures.
  相似文献   
126.
127.
The regeneration and establishment of osseointegration within oral peri‐implant bone defects remains a clinical challenge. Bone tissue engineering (BTE) is emerging as a promising alternative to autogenous and/or biomaterial‐based bone grafting. The objective of this systematic review was to answer the focused question: in animal models, do cell‐based BTE strategies enhance bone regeneration and/or implant osseointegration in experimental peri‐implant defects, compared with grafting with autogenous bone or only biomaterial scaffolds? Electronic databases were searched for controlled animal studies reporting on peri‐implant defects and implantation of mesenchymal stem cells (MSC) or other cells seeded on biomaterial scaffolds, following Preferred Reporting Items for Systematic reviews and Meta‐Analyses (PRISMA) guidelines. Random effects meta‐analyses were performed for the outcomes histomorphometric bone area fraction (BA) and bone‐to‐implant contact (BIC). Nineteen studies reporting on large animal models (dogs and sheep) were included. Experimental defects were created surgically (16 studies) or via ligature‐induced peri‐implantitis (LIPI, three studies). In general, studies presented with an unclear to high risk of bias. In most studies, MSC were used in combination with alloplastic mineral phase or polymer scaffolds; no study directly compared cell‐loaded scaffolds vs. autogenous bone. In three studies, cells were also modified by ex vivo gene transfer of osteoinductive factors. The meta‐analyses indicated statistically significant benefits in favour of: (a) cell‐loaded vs. cell‐free scaffolds [weighted mean differences (WMD) of 10.73–12.30% BA and 11.77–15.15% BIC] in canine surgical defect and LIPI models; and (b) gene‐modified vs. unmodified cells (WMD of 29.44% BA and 16.50% BIC) in canine LIPI models. Overall, heterogeneity in the meta‐analyses was high (I2 70–88%); considerable variation was observed among studies regarding the nature of cells and scaffolds used. In summary, bone regeneration and osseointegration in peri‐implant defects are enhanced by the addition of osteogenic cells to biomaterial scaffolds. Although the direction of treatment outcome is clearly in favour of BTE strategies, due to the limited magnitude of treatment effect observed, no conclusive statements regarding the clinical benefit of such procedures for oral indications can yet be made. Copyright © 2017 John Wiley & Sons, Ltd.  相似文献   
128.
Context: Intentional self-poisoning with the herbicide paraquat has a very high case-fatality and is a major problem in rural Asia and Pacific.

Objectives: We aimed to determine whether the addition of immunosuppression to supportive care offers benefit in resource poor Asian district hospitals.

Materials and methods: We performed a randomised placebo-controlled trial comparing immunosuppression (intravenous cyclophosphamide up to 1?g/day for two days and methylprednisolone 1?g/day for three days, and then oral dexamethasone 8?mg three-times-a-day for 14 days) with saline and placebo tablets, in addition to standard care, in patients with acute paraquat self-poisoning admitted to six Sri Lankan hospitals between 1st March 2007 and 15th November 2010. The primary outcome was in-hospital mortality.

Results: 299 patients were randomised to receive immunosuppression (147) or saline/placebo (152). There was no significant difference in in-hospital mortality rates between the groups (immunosuppression 78 [53%] vs. placebo 94 [62%] (Chi squared test 2.4, p?=?.12). There was no difference in mortality at three months between the immunosuppression (101/147 [69%]) and placebo groups (108/152 [71%]); (mortality reduction 2%, 95% CI: ?8 to +12%). A Cox model did not support benefit from high-dose immunosuppression but suggested potential benefit from the subsequent two weeks of dexamethasone.

Conclusions: We found no evidence that high dose immunosuppression improves survival in paraquat-poisoned patients. The continuing high mortality means further research on the use of dexamethasone and other potential treatments is urgently needed.  相似文献   
129.
130.
An efficient sequential multi-component method for the synthesis of N-arylpyrrole-3-carbaldehydes has been developed. This reaction involved a proline-catalyzed direct Mannich reaction-cyclization sequence between succinaldehyde and in situ generated Ar/HetAr/indolyl-imines, followed by IBX-mediated oxidative aromatization in one-pot operation. The practical utility of this procedure is shown at gram-scale and the synthesis of diverse bioactive fused heterocyclic scaffolds such as pyrroloquinoline, pyrrolo-oxadiazole, dihydro pyrroloquinoline, and pyrrolo-phenanthridine.

An efficient sequential multi-component method for the synthesis of N-arylpyrrole-3-carbaldehydes has been developed.  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