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   6203篇
  免费   687篇
  国内免费   165篇
耳鼻咽喉   193篇
儿科学   70篇
妇产科学   231篇
基础医学   358篇
口腔科学   83篇
临床医学   692篇
内科学   550篇
皮肤病学   52篇
神经病学   124篇
特种医学   739篇
外国民族医学   1篇
外科学   1377篇
综合类   660篇
预防医学   185篇
眼科学   36篇
药学   186篇
  1篇
中国医学   17篇
肿瘤学   1500篇
  2024年   16篇
  2023年   51篇
  2022年   134篇
  2021年   181篇
  2020年   127篇
  2019年   129篇
  2018年   145篇
  2017年   168篇
  2016年   172篇
  2015年   209篇
  2014年   361篇
  2013年   347篇
  2012年   423篇
  2011年   441篇
  2010年   451篇
  2009年   435篇
  2008年   445篇
  2007年   395篇
  2006年   359篇
  2005年   354篇
  2004年   314篇
  2003年   291篇
  2002年   245篇
  2001年   181篇
  2000年   162篇
  1999年   118篇
  1998年   92篇
  1997年   69篇
  1996年   30篇
  1995年   43篇
  1994年   38篇
  1993年   15篇
  1992年   18篇
  1991年   11篇
  1990年   9篇
  1989年   12篇
  1988年   13篇
  1987年   5篇
  1986年   4篇
  1985年   6篇
  1984年   4篇
  1983年   2篇
  1982年   6篇
  1981年   6篇
  1980年   7篇
  1979年   2篇
  1978年   4篇
  1977年   2篇
  1974年   2篇
  1972年   1篇
排序方式: 共有7055条查询结果,搜索用时 15 毫秒
121.
BACKGROUND Neuroblastoma(NB) is the most common type of extracranial solid tumour in children. The overall prognosis of NB is poor, but at the same time, NB shows significant clinical diversity. NB can demonstrate spontaneous regression or can differentiate into benign ganglioneuroma.CASE SUMMARY This study retrospectively analyzed the clinical data of a patient with spontaneous regression of stage Ⅲ NB who was admitted in May 2015. Studies of the spontaneous regression of NB published from October 1946 to September 2019 were retrieved through Pub Med. The clinical manifestations, diagnosis,treatment, and follow-up results were analysed.CONCLUSION Spontaneous regression of stage Ⅲ NB is rare in the clinic. The report of this case is an important supplement to the study of the spontaneous regression of NB.  相似文献   
122.
Purpose: Neurosurgical laser ablation is experiencing a renaissance. Computational tools for ablation planning aim to further improve the intervention. Here, global optimisation and inverse problems are demonstrated to train a model that predicts maximum laser ablation extent.

Methods: A closed-form steady state model is trained on and then subsequently compared to N?=?20 retrospective clinical MR thermometry datasets. Dice similarity coefficient (DSC) is calculated to provide a measure of region overlap between the 57?°C isotherms of the thermometry data and the model-predicted ablation regions; 57?°C is a tissue death surrogate at thermal steady state. A global optimisation scheme samples the dominant model parameter sensitivities, blood perfusion (ω) and optical parameter (μeff) values, throughout a parameter space totalling 11?440 value-pairs. This represents a lookup table of μeffω pairs with the corresponding DSC value for each patient dataset. The μeffω pair with the maximum DSC calibrates the model parameters, maximising predictive value for each patient. Finally, leave-one-out cross-validation with global optimisation information trains the model on the entire clinical dataset, and compares against the model naïvely using literature values for ω and μeff.

Results: When using naïve literature values, the model’s mean DSC is 0.67 whereas the calibrated model produces 0.82 during cross-validation, an improvement of 0.15 in overlap with the patient data. The 95% confidence interval of the mean difference is 0.083–0.23 (p?Conclusions: During cross-validation, the calibrated model is superior to the naïve model as measured by DSC, with +22% mean prediction accuracy. Calibration empowers a relatively simple model to become more predictive.  相似文献   
123.
IntroductionTo assess the value of referring to Diffusion-weighted images in evaluation of T2-weighted images of patients clinically suspicious of locoregional rectal cancer recurrence.MethodsAfter ethics committee approval and informed consent were obtained, 37 consecutive patients (male/female of 22/15; mean age 56 ± 13.5 SD) clinically suspicious of recurrent rectal tumor were prospectively included in the study over a two-year period. T2-weighted images of the patients were reviewed and the results were recorded. Right after that, the corresponding DWI images were provided for the radiologist and new ratings were given to the patients after taking into account the DWI findings. Finally, the patients underwent tissue biopsy. Receiver Operating Characteristic (ROC) analysis was performed, and Area Under the Curve (AUC) of the “T2-weighted alone” and “T2-weighted + DWI” methods were calculated and compared.Results“T2-weighted alone” and “T2-weighted + DWI” methods had an AUC of 0.64 (95% CI 0.47 to 0.79) and 0.75 (95% CI 0.58 to 0.88), respectively. The Difference between the two AUCs was 0.11 (P = 0.16). In the subgroup of patients having equivocal ratings in T2-weighted images, DWI images correctly identified 81% (13/16) of patients with true tumor recurrence and 66% (8/12) of patients without recurrence.ConclusionOur results suggest that referring to DWI does not significantly change the overall diagnostic performance of T2-weighted images. However, DWI is of great value in evaluation of the subgroup of patients with equivocal findings in T2-weighted images. Studies with larger sample sizes are needed to confirm these findings.Implications for practiceWhen T2-weighted images are equivocal, DWI images may be helpful in evaluation of patients with suspected locoregional recurrence of rectal tumor.  相似文献   
124.
ObjectiveTo investigate the occurrence of synchronous colorectal cancer metastases (SCCM) confined to the lungs, risk factors for these metastases and their impact on survival.MethodsIn a nationwide cohort study of 26,200 patients data were prospectively entered into the Danish Colorectal Cancer Group’s (DCCG’s) database between May 2001 and December 2011. The recorded data were merged with data from the Danish Pathology Registry and the National Patient Registry. Multivariable logistic- and extended Cox regression analyses were used to adjust for confounding variables.ResultsIn total, 1970 patients (7.5%) had pulmonary SCCM of whom 736 (37%) had metastases exclusively in the lungs. Advanced age, recent years of diagnosis and a rectal index cancer were significantly associated with pulmonary SCCM. Adjustment for excess use of thoracic CT scans in rectal cancer patients did not alter this association (adjusted OR = 1.81 (95% CI: 1.46–2.25, P < 0.001)). Patients subjected to pulmonary metastasectomy, resection of primary tumour and chemotherapy had a superior overall survival compared with non-treated patients, especially when these therapeutic modalities were combined.ConclusionsThe occurrence of pulmonary SCCM was higher than previously reported and had a severe impact on survival. Our analyses suggest that pulmonary metastasectomy, resection of the primary tumour and chemotherapy may be a sound strategy in patients with confined pulmonary SCCM, but the risk of selection bias and consequent exaggeration of the treatment effect should be kept in mind. This study may serve as a reliable un-biased reference for future evaluation on detection strategies and potential therapeutic interventions.  相似文献   
125.
Aim: Human Papillomavirus is one of the most crucial infectious disease in gynecology disease. To assess the efficacy of supplemental zinc treatment in clearance of HPV infection. Methods: Eighty zinc-sufficient women between 21-55 years, with positive HPV DNA testing, and abnormal cervical cytology in Pap test (ASCUS or LISL) were randomly divided to case (n=40) and control group (n=40). Case group received oral tablets of zinc sulfate twice a day for 3 months while control group received no placebo. During follow-up patients underwent repeat HPV DNA test and PAP test and were evaluated for clearance/persistence of HPV infection and regression/progression in the lesion grading. Results: As far as demographics, serum zinc levels and the relevant risk factors for persistence of HPV were concerned, there was no significant difference between two groups, except for the frequency distribution of HR-HPV which was significantly higher in case  group. Zinc treatment for 3 months reduced the risk of persistence of HPV infection and progression from baseline cytology (OR = 0.130) (CI 95% 0.04-0.381; p <0.001) and 0.301 (95% CI 0.777-0.116; p = 0.012), respectively. Age, initial cytology, HPV type, and contraceptive method were not related to persistence of HPV. Serum zinc levels increased in the casr group as a result of oral zinc consumption for 3-month period, though without any statistical significance (p = 0.407). Conclusion: The results of the following study suggested that oral intake of zinc sulfate supplement for 3 months increases the rates of HPV clearance and resolution of pre-existing cervical lesion.  相似文献   
126.
127.
Cutaneous mesenchymal neoplasms often pose significant diagnostic challenges; many such entities are rare or show clinical and histologic overlap with both other mesenchymal and non-mesenchymal lesions. Recent advances in the genetic classification of many cutaneous mesenchymal neoplasms have not only helped define unique pathologic entities and increase our understanding of their biology, but have also provided new diagnostic markers. This review details these recent discoveries, with a focus on their implications for tumor classification and diagnosis.  相似文献   
128.
目的:建立人原发性直肠恶性淋巴瘤裸小鼠原位移植模型,探讨其生物学特性.方法:采用人直肠原发性恶性淋巴瘤术中的新鲜瘤组织块植入裸鼠的直肠黏膜层内,观察原位移植的成瘤率,移植瘤的侵袭和转移率.进行形态学(光镜、电镜、免疫组织化学),染色体核型,流式细胞分析.结果:依据WHO新的分类标准,建成1株人直肠原发性(非霍奇金B细胞性)恶性淋巴瘤裸鼠原位移植模型HRBL-0305.移植瘤组织病理学为(非霍奇金B细胞性)高度恶性淋巴瘤;免疫组织化学示CD19,CD20,CD22,CD45阳性,CD3,CD7阴性.染色体众数56-69条,流式细胞DI值为1.57-1.61,均为异倍体.HRBL-0305已传至31代;共移植裸鼠187只.其肿瘤移植生长率和液氮冻存复苏成活率均为100.0%,肝转移率为45.4%,淋巴结和腹腔种植转移率均为38.0%,移植瘤在裸鼠的直肠内自主侵袭性生长,发生血液、淋巴转移和腹腔内种植性转移,移植瘤组织病理学,超微结构的观察,流式细胞DNA含量测定及染色体核型的分析,表明与人源直肠恶性淋巴瘤细胞相一致.结论:HRBL-0305是首次成功建立的人直肠原发性恶性淋巴瘤裸鼠原位移植模型,完整地重现了人直肠原发性恶性淋巴瘤的自然临床病理过程,且转移模式与临床患者相似,为研究直肠恶性淋巴瘤的生物学特性和治疗提供了理想动物模型平台.  相似文献   
129.
CD44 V6和MMP-9在胃癌及癌前病变组织中表达   总被引:1,自引:1,他引:1  
目的探讨CD44V6和基质金属蛋白酶9(MMP-9)在胃癌及癌前病变组织中表达。方法免疫组化SP法测定正常胃黏膜(NOR)、萎缩性胃炎伴中重度肠化(IM)、萎缩性胃炎伴中重度不典型增生(DYS)和早期胃癌(EGC)各40例,进展期胃癌(AGC)100例中CD44V6和MMP-9的表达。结果NOR、IM、DYS、EGC和AGC组中,分别有0、15.0%、25.0%、45.0%和72.0%CD44V6阳性,0、40.0%、50.0%、40.0%和68.0%MMP-9阳性。从IM、DYS至EGC和AGC组,CD44V6和MMP-9表达渐增(均P〈0.05)。结论CD44V6、MMP-9在胃痛的演变过程中不仅仅参与了浸润转移.其在胃癌早期发生、发展中也起着重要作用。  相似文献   
130.
Despite the availability of all advanced diagnostic tools, fever of unknown origin (FUO) remains a diagnostic challenge for physicians. The objective was to define, through a retrospective study, the categories of the diseases of Sicilian patients admitted at the Department of Clinical Medicine and Emerging Diseases, University of Palermo, Italy, for classical FUO. Using the registration system for patients admitted from 1991 to 2002, 508 charts of patients admitted because of fever were reviewed. Of these, only 91 patients fulfilled the criteria for classical FUO. The origin of FUO was diagnosed in 62 (68.1%) patients. Infection was the most common cause of FUO with 29 cases (31.8% of total of FUO), neoplasms accounted for 13 cases (14.2%), collagen vascular disease for 11 cases (12.0%), and miscellaneous for 9 cases (9.8%). Undiagnosed FUO were 29 (31.8%) and, of them, 22 cases were followed-up for 2 years. A definite diagnosis could be established only in 8 cases, 13 subjects completely recovered and 4 of them died. In the 73.4% of cases, the FUO have been the result of misleading factors in the diagnostic approaches as made by the physician. The results of our study are similar to those already reported by other authors in other populations, with infections as first, neoplasm as second, and collagen vascular diseases as third most important causes of FUO. In our study the prognosis for undiagnosed FUO cases was good, but a definite diagnosis could be established only in few cases. Therefore, further multicentric, prospective studies of good design are required.  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