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   3092篇
  免费   91篇
  国内免费   29篇
耳鼻咽喉   107篇
儿科学   161篇
妇产科学   20篇
基础医学   241篇
口腔科学   112篇
临床医学   166篇
内科学   497篇
皮肤病学   49篇
神经病学   267篇
特种医学   112篇
外科学   251篇
综合类   148篇
预防医学   271篇
眼科学   382篇
药学   303篇
  2篇
中国医学   69篇
肿瘤学   54篇
  2024年   3篇
  2023年   130篇
  2022年   172篇
  2021年   267篇
  2020年   201篇
  2019年   243篇
  2018年   217篇
  2017年   106篇
  2016年   71篇
  2015年   52篇
  2014年   276篇
  2013年   172篇
  2012年   165篇
  2011年   226篇
  2010年   163篇
  2009年   123篇
  2008年   105篇
  2007年   86篇
  2006年   69篇
  2005年   73篇
  2004年   31篇
  2003年   31篇
  2002年   13篇
  2001年   19篇
  2000年   22篇
  1999年   26篇
  1998年   9篇
  1997年   9篇
  1996年   7篇
  1995年   7篇
  1994年   10篇
  1993年   5篇
  1992年   8篇
  1991年   6篇
  1990年   8篇
  1989年   4篇
  1988年   7篇
  1987年   4篇
  1985年   18篇
  1984年   15篇
  1983年   7篇
  1982年   3篇
  1981年   6篇
  1980年   3篇
  1979年   3篇
  1977年   3篇
  1976年   1篇
  1975年   3篇
  1973年   1篇
  1969年   1篇
排序方式: 共有3212条查询结果,搜索用时 15 毫秒
41.
目的:对单纯行下斜肌后徙手术后水平斜视度的变化分析,探讨下斜肌后徙手术对原在位水平斜视度的影响.方法:收集2014-01/09在我院眼科行手术治疗的先天性上斜肌麻痹合并小角度水平斜视及小度数Ⅴ型斜视患者共30例,仅行下斜肌后徙手术,水平方向小度数斜视未行手术矫正.其中,先天性上斜肌麻痹患者25例,行单眼下斜肌后徙术;Ⅴ型斜视5例,行双眼下斜肌后徙术.随访3~6mo,术前、术后行33cm和6m三棱镜交替遮盖斜视度检查,同视机检查,Titmus立体图检查,Worth四点灯检查,眼球运动检查,眼底照相检查等,进而比较手术前后远、近水平斜视度变化(双侧者以1/2斜视度计算).结果:(1)外斜组23例(包括5例外斜Ⅴ征)手术前后看远、看近水平斜视度变化有统计学意义(P=0.00),术后分别使原在位外斜减小平均值3.35±2.87△,4.37±2.65△.(2)内斜组7例看远手术前后水平斜视度变化有统计学意义(P=0.02),术后使内斜减小平均值2.43±1.99△;看近手术前后水平斜视度变化无统计学意义(P=0.089).结论:下斜肌后徙手术后原在位外斜、内斜度数都有减小,这种变化通过手术后逐步完善、建立的融合功能代偿产生.  相似文献   
42.
Abstract

This paper presents a software-based scheme for reliable and robust Electrocardiogram (ECG) data compression and its efficient transmission using Second Generation (2G) Global System for Mobile Communication (GSM) based Short Message Service (SMS). To achieve a firm lossless compression in high standard deviating QRS complex regions and an acceptable lossy compression in the rest of the signal, two different algorithms have been used. The combined compression module is such that it outputs only American Standard Code for Information Interchange (ASCII) characters and, hence, SMS service is found to be most suitable for transmitting the compressed signal. At the receiving end, the ECG signal is reconstructed using just the reverse algorithm. The module has been tested to all the 12 leads of different types of ECG signals (healthy and abnormal) collected from the PTB Diagnostic ECG Database. The compression algorithm achieves an average compression ratio of ~22.51, without any major alteration of clinical morphology.  相似文献   
43.
44.
45.
The gerbil is a rodent considered a good model for studies of prostatic morphophysiology under different experimental conditions. Studies involving castration and steroidal blockers of aged gerbils showed that the glandular epithelium persists after long-term therapy, preventing the organ atrophy. Thus, the objective of this study was to evaluate the phenotypic characteristics and behavior of prostatic epithelial cells that remained after different periods of hormone ablation in aged gerbils. The identification of elements that influenced the survival of this cell type was performed by morphometric, nuclear phenotypes, ultrastructural and immune histochemical analysis. The most significant responses to treatment, by analyzing morphometric features, were observed during the first three time points (day 1, day 3, and day 7), after which there appeared to be an adjustment of the gland to the hormone ablation. All treatments led to changes in the state of chromatin condensation, DNA methylation pattern and phenotypic changes indicated cell senescence. Additionally, an increase in the basal cells seemed to guarantee self-renewal properties to the epithelium. These data indicate that changes occur at many levels, including gene expression and nuclear architecture in the epithelial cells, when aging and steroidal blockade are associated. These aspects are important when considering castration-resistant prostate cancer, a malignant tumor posing difficult therapeutic intervention.  相似文献   
46.
The longevity gene clk-1/coq7 encodes an enzyme that is essential for the biosynthesis of coenzyme Q (CoQ) in mitochondria and regulates the lifespan and behavioral timing in Caenorhabditis elegans and the chronological lifespan in fission yeast. However, whether the mammalian clk-1/coq7 ortholog (clk-1) regulates these phenotypes in mammals remains to be fully evaluated due to the embryonic lethality of clk-1-deficient (clk-1(-/-)) mice. To investigate whether clk-1 regulates biological functions, such as growth and heartbeat, through CoQ in mouse embryos, we cultivated the cells and hearts of clk-1(-/-) mouse embryos at embryonic day 10.5 (E10.5) for at least 10 days in the presence of fetal bovine serum. In embryonic cells, cardiomyocytes, and hearts, the growth and heart rates were significantly slowed in clk-1(-/-) compared with wild-type or heterozygous mouse tissues. Moreover, frequent apoptosis and a significant reduction in mitochondrial functions, including membrane potential and ATP production, were observed in the clk-1(-/-) cells and hearts. The slowed growth and heart rates and the reduced mitochondrial function of clk-1(-/-) embryonic cells and hearts in culture were almost completely rescued by the administration of exogenous CoQ(10). The results indicate that clk-1 regulates growth and heart rates through CoQ-mediated mitochondrial functions in mouse embryos.  相似文献   
47.
Objective:To evaluate the mean dimensions and morphologic characteristics of mandibular premolars that had mesiodistally elongated and faciolingually squeezed tooth shape deviations (MnP-TSD) and determine the population prevalence of this anomaly.Materials and Methods:Clinical photographs and study models were made for all new patients with MnP-TSD teeth who were seen over 20 years. The mesiodistal (MD) and faciolingual (FL) dimensions of the anomalous premolars were measured. MD/FL indices and MD × FL mm2 occlusal crown areas were calculated and means and standard deviations were derived. Male and female means from the mandibular first and second anomalous premolars (MnP1/MnP2-TSD) were statistically compared against gender-specific means derived from published normative data using Student''s t-tests and chi-square tests.Results:Fifty-six individuals (33 male and 23 female) with MnP-TSD were identified, giving a male to female ratio of 1.4∶1, while the prevalence rate in the indigenous British population was estimated to be 0.6%. The MD widths of the MnP1-TSD and MnP2-TSD teeth were approximately 1 mm wider than normal, while the FL diameters were about 0.5 mm and 1.5 mm narrower respectively, for the first and second premolar teeth. The MD/FL indices, instead of being under 90 as usual were above 100, while the mean MD/FL mm2 crown surface areas were normal.Conclusions:This study supplies odontometric dimensional and morphologic data on MnP-TSD teeth that provide a reference source for future comparisons.  相似文献   
48.
PurposeTo evaluate the volume reduction rate (VRR) of thyroid nodules over a long period of time after radiofrequency (RF) ablation treatment in both solid and mixed nodules; to determine ablation parameters; and to evaluate complications and success rates and safety of RF ablation.Material and MethodsIn this prospective study, 24 patients (83% females and 17% males; age 50.17 ± 13.6 years) underwent ultrasound-guided percutaneous RF ablation of benign thyroid nodules with radiologic follow-up at 1, 3, 6, 12, 24, and 36 months after treatment. All patients presented with compressive or cosmetic complaints and with Thyroid Imaging Reporting and Data System 1 or 2 nodules under ultrasound and were confirmed to be Bethesda Category II after 2 fine-needle aspirations.ResultsA total of 24 nodules (54.2% solid, 37.5% solid predominance, and 8.3% cystic predominance) were included in this study. Significant results in VRR (%) were found at 24 months and 36 months of 69.92 ± 19.23 and 76.84 ± 15.92, respectively. Furthermore, a logarithmic relationship was found when VRR was plotted over time, in both solid and mixed nodules. No correlations were found with any of the ablation parameters. The success rate reached 72.22% at 12 months, and the total complication rate was 16.67% (12.5% minor complications and 4.2% major complications—1 laryngeal nerve palsy), reaching an 83.3% safety.ConclusionsRF ablation can be an alternative treatment modality in the management of benign symptomatic thyroid nodules. The results show that it is a safe and effective treatment if trans-isthmic approach and moving-shot techniques are correctly followed.  相似文献   
49.
Objectives: This research aimed to evaluate pre-operatively and post-operatively the olfactory function of patients who had undergone surgery in our clinic for chronic nasal blockage via the Connecticut Chemosensory Clinical Research Center (CCCRC) smell test.

Method: Thirty-seven patients (24 females, 13 males) were enrolled in this study. All had undergone surgery in our clinic due to chronic nasal blockage (not for smell dysfunction), having been diagnosed with septal deviation in conjunction with concha bullosa and/or inferior turbinate hypertrophy. This is a prospective study without a control group. The mean age was 33.74?±?8.98 (range =19–54). All of the operations were performed under general anesthesia. CCCRC smell tests were performed on every patient before the operation and at post-operative 1st week, 6th week, 6th month, and 1st year.

Results: In this study, we found that septoplasty, in conjunction with middle concha surgery and/or inferior concha radiofrequency, did not affect the olfactory function negatively.

Conclusion: Although nasal surgery has the potential to affect the smell function negatively, it was found that olfactory function was not affected after the surgery during a considerably long follow-up period. Moreover, an improvement in smell function was detected at post-operative 6th month and 1st year.  相似文献   
50.
目的 总结抗生素微生物检定法(管碟法)中影响测定结果准确性的常见系统误差并加以控制。方法 梳理10余年来中检院仲裁复验的案例,对共性问题进行整理,找出可能原因,并采用单一变量实验设计的方式加以确证。结果 估计效价和浓度比的错误计算、点样顺序和点样时间规范性和熟练程度、试验标准菌株的变异均会对管碟法测定结果产生影响。结论 通过细化实验操作规范,可以避免或尽量消除此类系统误差的影响。  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