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   3759篇
  免费   296篇
  国内免费   274篇
耳鼻咽喉   17篇
儿科学   23篇
妇产科学   59篇
基础医学   509篇
口腔科学   74篇
临床医学   468篇
内科学   674篇
皮肤病学   16篇
神经病学   245篇
特种医学   131篇
外国民族医学   7篇
外科学   315篇
综合类   592篇
现状与发展   1篇
预防医学   185篇
眼科学   95篇
药学   387篇
中国医学   160篇
肿瘤学   371篇
  2024年   7篇
  2023年   65篇
  2022年   92篇
  2021年   182篇
  2020年   147篇
  2019年   125篇
  2018年   114篇
  2017年   115篇
  2016年   106篇
  2015年   173篇
  2014年   204篇
  2013年   194篇
  2012年   299篇
  2011年   299篇
  2010年   162篇
  2009年   135篇
  2008年   196篇
  2007年   183篇
  2006年   180篇
  2005年   217篇
  2004年   130篇
  2003年   155篇
  2002年   106篇
  2001年   78篇
  2000年   91篇
  1999年   95篇
  1998年   71篇
  1997年   73篇
  1996年   42篇
  1995年   42篇
  1994年   33篇
  1993年   27篇
  1992年   21篇
  1991年   32篇
  1990年   17篇
  1989年   21篇
  1988年   12篇
  1987年   13篇
  1986年   13篇
  1985年   3篇
  1984年   8篇
  1983年   9篇
  1982年   4篇
  1981年   10篇
  1980年   2篇
  1979年   7篇
  1978年   3篇
  1976年   3篇
  1971年   3篇
  1967年   3篇
排序方式: 共有4329条查询结果,搜索用时 279 毫秒
1.
BackgroundComminuted patellar fractures are not rare, and the ideal treatment method remains controversial. The present study was conducted to evaluate effects and compare complications of two different methods used to treat comminuted patellar fractures.MethodsFrom March 2010 to August 2016, 102 cases of 34-C2 or 34-C3 comminuted patellar fractures were treated at our hospital, wherein patients received two different treatments: titanium cable tension band with cerclage method (group A) and intrafragmentary screws with X-shaped plating technique (group B). At follow-ups, articular step-off, range of motion (ROM), Lysholm scores, time of union, and complications were recorded and analyzed. Radiographic and clinical data as well as rate of complications were statistically analyzed.ResultsIn total, 87 patients were included in the final analysis (n = 47 in group A and n = 40 in group B). No significant differences were noted in terms of cost of implant, age, gender, rate of 34-C3 fractures, rate of layered inferior pole fractures, postoperative articular step-off and union time. At 2-year follow-up, average Lysholm scores, ROM and rate of complications were (89.0 ± 4.5), (122°±12°) and (27.7%) in group A and (90.2 ± 3.9), (124°±11°) and (17.5%) in group B, respectively, with no significant differences (p > 0.05). The mean time of surgery in group B was shorter than that in group A with significant difference (p < 0.05).ConclusionsTreatment using the intrafragmentary screws and plate method for amenable comminuted patellar fractures achieved similar complication rate and favorable functional outcomes at the 2-year follow-up, which was comparable to the titanium cable tension band with cerclage method. Thus, the intrafragmentary screws and plate method is effective, safe and convenient for 34-C2/C3 comminuted patellar fractures, especially appropriate for patients with layered fragments.  相似文献   
2.
3.
目的 探讨CT引导徒手腔内联合插植实现影像引导自适应后装(IGABT)相较于传统A点二维后装(CP)剂量学优势,明确其在宫颈癌治疗中的价值。方法 选取在中山大学肿瘤医院行全量放疗的宫颈癌患者 26例,每例患者行4次后装治疗。治疗时先徒手置入宫腔管及2根插植针,后增加插植针数量并调整方向、深度,分别行CT扫描获得2套图像。勾画高危临床靶区(HRCTV),A点和危及器官(直肠、膀胱及乙状结肠)。在2套图像上分别行CP和IGABT计划设计,并配对t检验、Wilcoxon检验两者剂量参数差异。结果 以CP计划的覆盖指数(CI)进行分组,A组(CI≥0.90)包含20个CP和对应IGABT计划,B组(CI<0.90)包含84个CP和对应IGABT计划。A组的HRCTV体积及肿瘤直径明显小于B组(46.7cm3∶62.1cm3,P<0.001及3.1cm∶4.4cm,P<0.0001)。IGABT显著提高所有及B组D90%及覆盖指数,降低膀胱剂量,减少A组乙状结肠剂量,并改善剂量适形度及均匀性。结论 IGABT能提高靶区覆盖、剂量适形度和均匀性,保护危及器官,且对肿瘤较大的患者仍有优势。  相似文献   
4.
ObjectivesTo investigate the effect of corneal stromal pocket irrigation after small-incision lenticule extraction (SMILE) on visual acuity, intraocular pressure (IOP), corneal parameters and complications after surgery.MethodsA total of 242 eyes of 121 patients undergoing SMILE were enrolled in this prospective controlled study, and it was designed for one eye to randomly undergo SMILE with balanced salt solution irrigation of the corneal stromal pocket, while the other eye was not. The uncorrected distance visual acuity (UDVA) and slit lamp examination were recorded at 1 hour, 1 day, 1 week, and 1 month. Postoperative corneal density, corneal biomechanical, corneal endothelial cell number, and anterior OCT images were compared at 1 day, 1 week, and 1 month.ResultsCompared with the nonirrigation group, the irrigation group showed significantly higher UDVA at 1 day postoperatively (P < 0.05), but there was no significant difference during the rest of the postoperative period (1 hour, 1 week, and 1 month). In addition, no significant differences were found in IOP, corneal density, corneal biomechanics, corneal endothelial cells, and corneal morphology. No visual decline or severe postoperative complications were found in the patients in this study.ConclusionsInterlamellar irrigation did not affect IOP, corneal parameters, morphology, complications, or UDVA at 1 hour, 1 week, and 1 month after the operation, but it may promote UDVA 1 day after the operation.Subject terms: Refractive errors, Outcomes research, Surgery  相似文献   
5.
The prevalence and clinical relevance of TP53 germline mutations in a large unselected breast cancer series are largely unknown. Here, we determined TP53 germline mutations in a large cohort of 10,053 unselected breast cancer patients through multigene panel-based next-generation and/or Sanger sequencing assays. We found that 0.5% of patients (50 cases) carried a pathogenic TP53 germline mutation in this large series of 10,053 unselected breast cancer patients, and the prevalence of TP53 germline mutation was 3.8% in very early onset breast cancer (age ≤30 years) in this large cohort. TP53 mutation carriers were significantly more likely to have early onset cancer (p < 0.001) and bilateral breast cancer (p = 0.03), they and were significantly more likely to respond to carboplatin-based neoadjuvant chemotherapy compared to anthracycline- or taxane-based regimen in terms of pathologic complete response (50% vs. 0%, p = 0.006). At the median follow-up of 54 months, TP53 mutation was an independent unfavorable factor for recurrence-free survival (RFS), distant recurrence-free survival (DRFS), and overall survival (OS) (RFS, adjusted hazard ratio [HR]: 2.24, 95% confidence interval [CI]: 1.15–4.33, p = 0.02; DRFS, adjusted HR: 2.73, 95% CI: 1.41–5.30, p = 0.003; OS, adjusted HR: 4.60, 95% CI: 2.26–9.41, p < 0.001) in multivariate analyses. Our study suggested that TP53 germline mutations occur more frequently in very early onset unselected breast cancer patients; and TP53 germline mutation carriers have a very poor survival and may benefit from carboplatin-based neoadjuvant chemotherapy in unselected breast cancer patients.  相似文献   
6.
7.

Background

Attention-deficit hyperactivity disorder (ADHD) is a common childhood neuropsychiatric disorder. Diagnosis of ADHD is based on core symptoms or checklists; however, practitioner subjectivity inevitably results in instances of over- or under-diagnosis. Although an elevated theta/beta ratio (TBR) of the electroencephalography (EEG) band has been approved by the Food and Drug Administration as a factor that may be used in diagnosis of ADHD, several studies have reported no significant differences between the TBR of patients with ADHD and controls.

Purpose

In this study, a method was developed based on Hjorth Mobility (M) analysis of EEG to compare patients with ADHD and controls.

Methods

Differences in the presentations of ADHD between boys and girls are well established; therefore, separate investigations are required. The present study enrolled 30 girls with ADHD and 30 age-matched controls.

Results

The results revealed that the control group had significantly higher Hjorth M values in most brain areas in EEG readings compared with the values for the ADHD group. Compared with TBR, our method revealed a greater number of more significant differences between the girls in the ADHD group and the controls. Moreover, our method can produce the higher average sensitivity (0.796), average specificity (0.796), average accuracy (0.792), and average area under the curve of receiver operating characteristic curve (AUC) value (0.885). Therefore, compared with TBR, Hjorth M possessed the better potential for differentiating between girls with ADHD and controls.

Conclusion

The proposed method was more accurate than the TBR in diagnosing ADHD. Therefore, Hjorth M may be a promising tool for differentiating between children with ADHD and controls.  相似文献   
8.
Stress has been suggested to disturb the 5-hydroxytryptamine system and decrease neurogenesis, which contribute to the development of depression. Few studies have investigated the effect of predator stress, a type of psychological stress, on depression and hippocampal neurogenesis in adult mice; we therefore investigated this in the present study. A total of 35 adult male Kunming mice were allocated to a cat stress group, cat odor stress group, cat stress + fluoxetine group, cat odor stress + fluoxetine group, or a control group(no stress/treatment). After 12 days of cat stress or cat odor stress, behavioral correlates of depression were measured using the open field test, elevated plus maze test, and dark-avoidance test. The concentrations of hippocampal 5-hydroxytryptamine and 5-hydroxyindoleacetic acid were measured using high-performance liquid chromatography-electrochemical detection. Neurogenesis was also analyzed using a bromodeoxyuridine and doublecortin double-immunostaining method. Cat stress and cat odor stress induced depression-like behaviors; this effect was stronger in the cat stress model. Furthermore, compared with the control group, cat stress mice exhibited lower 5-hydroxytryptamine concentrations, higher 5-hydroxyindoleacetic acid concentrations, and significantly fewer bromodeoxyuridine+/doublecortin+-labeled cells in the dentate gyrus, which was indicative of less neurogenesis. The changes observed in the cat stress group were not seen in the cat stress + fluoxetine group, which suggests that the effects of predator stress on depression and neurogenesis were reversed by fluoxetine. Taken together, our results indicate that depression-like behaviors induced by predator stress are associated with the inhibition of hippocampal neurogenesis.  相似文献   
9.
10.
Helicobacter pylori (H. pylori) is a main risk factor for gastric cancer (GC). Epithelial-mesenchymal transition (EMT) is involved in the development and progression of H. pylori-associated GC. However, the exact molecular mechanism of this process remains unclear. The AKT/GSK3β signaling pathway has been demonstrated to promote EMT in several types of cancer. The present study investigated whether H. pylori infection induced EMT, and promoted the development and metastasis of cancer in the normal gastric mucosa, and whether this process was dependent on AKT activation. The expression levels of the EMT-associated proteins, including E-cadherin and N-cadherin, were determined in 165 gastric mucosal samples of different disease stages by immunohistochemical analysis. The expression levels of E-cadherin, N-cadherin, AKT, phosphorylated (p-)AKT (Ser473), GSK3β and p-GSK3β (Ser9) were further determined in H. pylori-infected Mongolian gerbil gastric tissues and cells co-cultured with H. pylori by immunohistochemical analysis and western blotting. The results indicated that the expression levels of the epithelial marker E-cadherin were decreased, whereas the expression levels of the mesenchymal marker N-cadherin were increased during gastric carcinogenesis. Their expression levels were associated with H. pylori infection. Furthermore, H. pylori infection resulted in downregulation of E-cadherin expression and upregulation of N-cadherin expression in Mongolian gerbils and GES-1 cells. In addition, an investigation of the associated mechanism of action revealed that p-AKT (Ser473) and p-GSK3β (Ser9) were activated in GES-1 cells following co-culture with H. pylori. Furthermore, following pretreatment of the cells with the AKT inhibitor VIII, the expression levels of E-cadherin, N-cadherin, p-AKT and p-GSK3β did not show significant differences between GES-1 cells that were co-cultured with or without H. pylori. The levels of p-AKT and p-GSK3β were increased in H. pylori-infected Mongolian gerbils. In conclusion, the present study demonstrated that H. pylori infection activated AKT and resulted in the phosphorylation and inactivation of GSK3β, which in turn promoted early stage EMT. These effects were AKT-dependent. This mechanism may serve as a prerequisite for GC development.  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