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   3871篇
  免费   142篇
  国内免费   27篇
耳鼻咽喉   177篇
儿科学   79篇
妇产科学   119篇
基础医学   562篇
口腔科学   31篇
临床医学   340篇
内科学   1050篇
皮肤病学   12篇
神经病学   263篇
特种医学   116篇
外科学   449篇
综合类   30篇
一般理论   3篇
预防医学   179篇
眼科学   71篇
药学   289篇
中国医学   2篇
肿瘤学   268篇
  2024年   4篇
  2023年   28篇
  2022年   156篇
  2021年   244篇
  2020年   66篇
  2019年   108篇
  2018年   139篇
  2017年   86篇
  2016年   102篇
  2015年   116篇
  2014年   165篇
  2013年   219篇
  2012年   320篇
  2011年   353篇
  2010年   175篇
  2009年   107篇
  2008年   232篇
  2007年   233篇
  2006年   267篇
  2005年   224篇
  2004年   228篇
  2003年   191篇
  2002年   134篇
  2001年   19篇
  2000年   9篇
  1999年   8篇
  1998年   14篇
  1997年   10篇
  1996年   10篇
  1995年   9篇
  1994年   6篇
  1993年   6篇
  1992年   6篇
  1991年   4篇
  1990年   9篇
  1989年   6篇
  1988年   4篇
  1987年   3篇
  1985年   2篇
  1983年   2篇
  1982年   1篇
  1981年   3篇
  1980年   2篇
  1979年   1篇
  1978年   2篇
  1977年   1篇
  1976年   1篇
  1975年   3篇
  1974年   1篇
  1971年   1篇
排序方式: 共有4040条查询结果,搜索用时 15 毫秒
81.
Dual-energy X-ray absorptiometry (DXA) method is widely used in pediatrics in the study of bone density and body composition. However, there is a limit to how precise DXA can estimate bone and body composition measures in children. The study was aimed to (1) evaluate precision errors for bone mineral density, bone mass and bone area, body composition, and mechanostat parameters, (2) assess the relationships between precision errors and anthropometric parameters, and (3) calculate a “least significant change” and “monitoring time interval” values for DXA measures in children of wide age range (5–18 yr) using GE Lunar Prodigy densitometer. It is observed that absolute precision error values were different for thin and standard technical modes of DXA measures and depended on age, body weight, and height. In contrast, relative precision error values expressed in percentages were similar for thin and standard modes (except total body bone mineral density [TBBMD]) and were not related to anthropometric variables (except TBBMD). Concluding, due to stability of percentage coefficient of variation values in wide range of age, the use of precision error expressed in percentages, instead of absolute error, appeared as convenient in pediatric population.  相似文献   
82.
The authors describe the use of bone cement containing calcium phosphate for vertebroplasty of the cavity in the base of odontoid process. A 23-year-old female patient was operated on by incision in lateral cervical area (anterior open access). After a blunt dissection, the working cannula (Kyphon) was introduced under fluoroscopic guidance through the C2 vertebral body to the cavity in the base of the odontoid process. Intraoperatively biopsy of the lesion was taken and histopathological examination excluded the presence of neoplasm. The cavity, presumably haemangioma, was successfully filled with calcium phosphate bone cement KyphOs? FS (Kyphon). The proper filling without paravertebral cement leak was confirmed by postoperative computed tomography (CT). The CT and magnetic resonance imaging performed 9 months after the procedure showed that cement was still present in the cavity. This is the first use of calcium phosphate cement to conduct the vertebroplasty of C2 vertebra.  相似文献   
83.
PURPOSETo report the outcomes for 76 patients with penile cancer treated with high-dose-rate brachytherapy (HDR-BT) at a single institution.METHODSSeventy-six patients with penile cancer treated with HDR-BT in our department between October 1998 and September 2018 were analyzed. Seventy underwent interstitial HDR-BT (fractionation dose range of 3–3.5 Gy given twice a day with an interval of at least six hours between the fractions), and six underwent superficial treatment with mold applicators (fractionation dose range of 4–7 Gy given once or twice a week).RESULTSMedian follow-up was 76 months (7–204 months). In the whole group, 22/76 local failures (28.9%) were observed: 14/76 (18.4%) local recurrences and 8/76 (10.5%) cases of persistent disease. Median time to recurrence was 24 months (9–54 months). Inguinal lymph node metastases were observed in 18/76 cases (23.7%). Distant metastases occurred in 12/76 (15.8%) cases. Patients with local recurrence and persistent disease underwent salvage penectomies, except four who refused surgery and underwent a second course of interstitial HDR-BT. Five- and 10-year cause-specific survival were 85.0% and 77.8%, respectively. Local control at 5 and 10 years was 65.6%. Five- and 10-year penile preservation were 69.5% and 66.9%, respectively. There was no G3 or G4 acute toxicity. One urethral stenosis (1.3%) occurred in a patient with a T3 tumor and was treated successfully with dilatation.CONCLUSIONSHDR-BT provides good local control of penile cancer and is a good option for penis preservation therapy and in our experience achieves a penile preservation rate at 10 years of 66.9%.  相似文献   
84.
Long‐term hemodialysis catheter dwell time in the central vein predisposes to fibrin sheath development, which subsequently causes catheter malfunction or occlusion. In very rare cases, the catheter can be overgrown with fibrin and rigidly connected with the vein or heart structures. This makes its removal almost impossible and dangerous because of the possibility of serious complications, namely vein and heart wall perforation, bleeding, or catheter abruption in deep tissues. We describe two cases in which standard retrieval of long‐term catheters was not possible. Balloon dilatation of catheter lumens was successfully used to increase the catheter diameter with simultaneous tearing of the fibrin sheath surrounding it. This allowed the catheter to be set free safely. Based on this experience, we present recent literature and our point of view.  相似文献   
85.
86.
87.
Introduction: The aim of the study was to evaluate some selected parameters of the antioxidative system in patients with type 2 diabetes. Materials and Methods: Eighty-one type 2 diabetes patients took part in the study (39 patients with metabolically balanced and 42 with metabolically unbalanced diabetes). The control group consisted of 30 healthy people. The total antioxidant capacity of plasma was measured fluorometrically using phycoerythrin. To calculate the low-molecular-weight antioxidant concentration in the plasma samples, the duration of Trolox activity as a function of its concentration in the sample was measured. The activity of antioxidative enzymes in red blood cells was determined using the Misra and Fridovich method and Beers and Sizer method. Results: The total plasma antioxidant capacity and the low-molecular-weight antioxidant concentration in the group of patients with metabolically compensated type 2 diabetes were statistically significantly higher than in the group of patients with metabolically uncontrolled diabetes. The activity of antioxidative enzymes was found to be higher in the group of type 2 diabetes patients at the stage of metabolic balance. Conclusions: The obtained results confirm the thesis of glucose toxicity and intensification of oxidative stress in patients with diabetes.  相似文献   
88.
Immunohistochemical analyses (IHC) of biomarkers are extensively used for tumor characterization and as prognostic and predictive measures. The current standard of single slide analysis assumes that one 5 microM section is representative of the entire tumor. We used our automated image analysis technology (AQUA) using a modified IHC technique with fluorophores to compare estrogen receptor (ER) expression in multiple blocks/slides from cases of primary breast cancer with the objective of quantifying tumor heterogeneity within sections and between blocks. To normalize our ER scores and allow slide-to-slide comparisons, 0.6 microm histospots of representative breast cancer cases with known ER scores were assembled into a 'gold standard array' (GSA) and placed adjacently to each whole section. Overall, there was excellent correlation between AQUA scores and the pathologist's scores and reproducibility of GSA scores (mean linear regression R value 0.8903). Twenty-nine slides from 11 surgical cases were then analyzed totaling over 2000 AQUA images. Using standard binary assignments of AQUA (>10) and pathologist's (>10%) scores as being positive, there was fair concordancy between AQUA and pathologist scores (73%) and between slides from different blocks from the same cases (75%). However using continuous AQUA scores, agreement between AQUA and pathologist was far lower and between slides from different blocks from the same cases only 19%. Within individual slides there was also significant heterogeneity in a scattered pattern, most notably for slides with the highest AQUA scores. In sum, using a quantitative measure of ER expression, significant block-to-block heterogeneity was found in 81% of cases. These results most likely reflect both laboratory-based variability due to lack of standardization of immunohistochemistry and true biological heterogeneity. It is also likely to be dependent on the biomarker analyzed and suggests further studies should be carried out to determine how these findings may affect clinical decision-making processes.  相似文献   
89.
In this study, we applied various assays to reveal new activities of phenylcyanomethylenequinone oxime-4-(hydroxyimino) cyclohexa-2,5-dien-1-ylidene](phenyl)ethanenitrile (4-AN) for potential anti-microbial applications. These assays demonstrated (a) the antimicrobial effect on bacterial and fungal cultures, (b) the effect on the in vitro activity of the kinase CK2, (c) toxicity towards human erythrocytes, the Caco-2 cancer cell line, and embryonic development of Zebrafish. We demonstrated the activity of 4-AN against selected bacteria and Candida spp. The MIC ranging from 4?µg/ml to 125?µg/ml proved effective in inhibition of formation of hyphae and cell aggregation in Candida, which was demonstrated at the cytological level. Noteworthy, 4-AN was found to inhibit the CK2 kinase with moderate potency. Moreover, at low concentrations, it did not exert any evident toxic effects on human erythrocytes, Caco-2 cells, or Zebrafish embryos. 4-AN can be a potential candidate as a novel drug against Candida infections.  相似文献   
90.
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