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   5209篇
  免费   285篇
  国内免费   148篇
耳鼻咽喉   143篇
儿科学   27篇
妇产科学   61篇
基础医学   771篇
口腔科学   47篇
临床医学   439篇
内科学   565篇
皮肤病学   40篇
神经病学   666篇
特种医学   245篇
外科学   937篇
综合类   613篇
预防医学   160篇
眼科学   56篇
药学   241篇
  2篇
中国医学   54篇
肿瘤学   575篇
  2024年   13篇
  2023年   70篇
  2022年   164篇
  2021年   204篇
  2020年   190篇
  2019年   171篇
  2018年   185篇
  2017年   163篇
  2016年   165篇
  2015年   198篇
  2014年   345篇
  2013年   305篇
  2012年   283篇
  2011年   292篇
  2010年   232篇
  2009年   303篇
  2008年   252篇
  2007年   251篇
  2006年   238篇
  2005年   148篇
  2004年   166篇
  2003年   134篇
  2002年   104篇
  2001年   91篇
  2000年   89篇
  1999年   71篇
  1998年   95篇
  1997年   65篇
  1996年   76篇
  1995年   52篇
  1994年   53篇
  1993年   43篇
  1992年   44篇
  1991年   38篇
  1990年   40篇
  1989年   28篇
  1988年   27篇
  1987年   31篇
  1986年   25篇
  1985年   39篇
  1984年   26篇
  1983年   21篇
  1982年   20篇
  1981年   23篇
  1980年   22篇
  1979年   13篇
  1978年   10篇
  1977年   4篇
  1976年   12篇
  1973年   3篇
排序方式: 共有5642条查询结果,搜索用时 15 毫秒
141.
Intussusception of the appendix is an uncommon condition, and the diagnosis is rarely made preoperatively. Making an accurate diagnosis before laparotomy is important in providing the optimal treatment for the patient. We present the clinical and endoscopic features of two cases of intussusception of the appendix and review the literature. Diagnosis was made preoperatively by colonoscopy in these cases and an elective appendectomy was performed. Appendiceal intussusception should be considered in the differential diagnosis of abdominal pain. Colonoscopy can be a valuable tool in establishing this diagnosis and in selecting the appropriate management Accepted: 18 April 2000  相似文献   
142.
BACKGROUND: Alcoholics are at risk of developing major complications in the postoperative period. Adequate prophylactic treatment, as well as preoperative abstinence, can significantly decrease the rate of complications. However, the preoperative diagnosis of alcoholism is difficult to establish. The purpose of this study was to assess whether three preoperative visits, an alcohol-related questionnaire (CAGE), and the laboratory markers carbohydrate-deficient transferrin (CDT) and gamma-glutamyltransferase (GGT) would increase the rate of detection of chronic alcoholics. METHODS: The study included the Departments of ENT, Facial and Maxillofacial Surgery, and General Surgery of a university hospital; 705 male patients were assessed for tumor surgery of the upper digestive tract and were allocated to 5 different groups. All patients were seen three times, and five different strategies were used to detect chronic alcoholics. The gold standard was the diagnosis of alcohol misuse made by an experienced (blinded) investigator according to the DSM-III-R. The main outcome measurements were the detection rates of the different test strategies. RESULTS: By clinical routine alone, only 16% were detected during the first visit and 34% after three visits. If the CAGE questionnaire was added, sensitivity increased to 64%. The further addition of GGT or CDT led to 80 and 85% detections, respectively. A combination of all tests had a sensitivity of 91%. CONCLUSIONS: To detect more alcoholic patients at risk for major complications, patients should be seen more often, and additional diagnostic tools such as the CAGE, CDT, and GGT should be used before surgery.  相似文献   
143.
目的 评价低频小探头超声内镜检查(LFMPS)在胰腺内分泌肿瘤术前定位诊断中的临床价值。方法 2000年6月至2002年6月期间21例临床拟诊为胰腺内分泌肿瘤的患者术前行腹部 B超、螺旋 CT、磁共振(MRI)及 LFMPS探查(Fujinon 7.5 MHz低频小探头超声及超声系统),检查结果与外科术中定位和病理结果对照,评估LFMPS对胰腺内分泌肿瘤的术前定位诊断价值。结果21例患者中17例经外科手术及术后病理证实为内分泌肿瘤,4例未手术。其中胰岛素瘤16例(头部9例、体部 3例、尾部4例),胰腺外血管活性肠肽瘤1例,检出病灶的平均直径 2.02 cm。LFMPS确诊14例(82.4%),B超确诊9例(52.9%),螺旋CT确诊15例(88.2%),MRI确诊12例(70.6%),其中LFMPS对位于胰腺头、体部肿瘤以及直径<1cm病灶的确诊率优于其他常规影像方法。结论LFMPS对胰腺内分泌肿瘤的术前定位诊断准确率较高,且与肿瘤的位置与大小有关。  相似文献   
144.
PURPOSE: Prediction of success after anterior sphincter repair for incontinence is difficult. Standard multivariate analysis techniques have only 75 to 80 percent accuracy. Artificial intelligence, including artificial neural networks, has been used in the analysis of complex clinical data and has proved to be successful in predicting the outcome of other surgical procedures. Using a neural network algorithm, we have assessed the probability of success after anterior sphincter repair. METHODS: Prospective anorectal physiology data of 72 patients undergoing anterior sphincter repair was collected between 1995 and 1999. Complete data sets of 75 percent of the series were used to train an artificial neural network; the remaining 25 percent were used for data validation. The output was continence grading, ranging from 0 to 4 (worse to continent). RESULTS: The outcome at 3, 6, and 12 months postoperatively was obtained and assessed. The best correlation between actual data value and artificial neural network value was found at 12 months (r = 0.931; P = 0.0001). Clear correlations also were found at three months (r = 0.898; P = 0.0001) and six months (r = 0.742; P = 0.002). Results of applying a net to details excluding pudendal nerve latency were poor. CONCLUSIONS: Artificial neural networks are more accurate (93 percent correlation) than standard statistics (75 percent) when applied to the prediction of outcome after anterior sphincter repair. This assessment also confirms the usefulness of pudendal latency in the prediction of anterior sphincter repair outcome. The results obtained highlight the obvious usefulness of artificial neural networks, which could now be used in a prospective evaluation for application of the technique.  相似文献   
145.
The nuclear protein I2PP2A/SET, an endogenous inhibitor of protein phosphatase-2A (PP2A), is increased and translocated to the cytoplasm in the neurons of Alzheimer's disease (AD) brains, and PP2A activity in cytoplasm is compromised. However, it is not fully understood how SET is retained in the cytoplasm. By generating a phosphorylation site-specific antibody, we found in the present study that SET is phosphorylated at Ser9, by which it is accumulated in the cytoplasm of the AD brains. Further studies demonstrate that both the phosphor-mimic and casein kinase (CK)II-mediated phosphorylation at Ser9 interferes with the formation of the SET/importin-α/importin-β complex, and thus inhibits SET nuclear import and induces the cytoplasmic detention of SET. Interestingly, Ser9 is nested in the center of the sequence 6AKVSKK11 of SET, which is consistent with a classical nuclear localization signal (NLS). To test whether 6AKVSKK11 is a new NLS of SET, we mutated SET lysine 7, lysine 10, and lysine 11 to alanine acid (K7A, K10A, K11A) respectively, and expressed these mutants in HEK293/tau cells. We found that expression of SET (K11A) led to a nuclear import defect of SET, and application of a synthesized peptide Tat-AAKVSKKE that can competitively bind to importin α/β resulted in cytoplasmic detention of SET. Finally, phosphorylation of SET aggravates PP2A inhibition and leads to tau hyperphosphorylation. In conclusion, the current study has identified a novel mechanism that causes cytoplasmic detention of SET with a new NLS-dependent CKII-associated phosphorylation of Ser9, suggesting that inhibition of CKII arrests cytoplasmic accumulation of SET and thus preserves PP2A activity in AD brains.  相似文献   
146.
Pain arises from the integration of sensory and cognitive processes in the brain, resulting in specific patterns of neural oscillations that can be characterized by measuring electrical brain activity. Current source density (CSD) estimation from low‐resolution brain electromagnetic tomography (LORETA) and its standardized (sLORETA) and exact (eLORETA) variants, is a common approach to identify the spatiotemporal dynamics of the brain sources in physiological and pathological pain‐related conditions. However, there is no consensus on the magnitude and variability of clinically or experimentally relevant effects for CSD estimations. Here, we systematically examined reports of sample size calculations and effect size estimations in all studies that included the keywords pain, and LORETA, sLORETA, or eLORETA in Scopus and PubMed. We also assessed the reliability of LORETA CSD estimations during non‐painful and painful conditions to estimate hypothetical sample sizes for future experiments using CSD estimations. We found that none of the studies included in the systematic review reported sample size calculations, and less than 20% reported measures of central tendency and dispersion, which are necessary to estimate effect sizes. Based on these data and our experimental results, we determined that sample sizes commonly used in pain studies using CSD estimations are suitable to detect medium and large effect sizes in crossover designs and only large effects in parallel designs. These results provide a comprehensive summary of the effect sizes observed using LORETA in pain research, and this information can be used by clinicians and researchers to improve settings and designs of future pain studies.  相似文献   
147.
BackgroundAltered muscle activation patterns and proprioception, loss of strength, and weight bearing asymmetries are common limitations after total knee arthroplasty, which can also affect balance. Therefore, preoperative sensorimotor training has been proposed to enhance surgical outcome.Research questionIs preoperative sensorimotor training effective in improving functional outcome in patients undergoing total knee arthroplasty? Does preoperative sensorimotor training affect secondary outcomes such as balance, pain, and quality of life?MethodsA systematic review and meta-analysis were conducted by searching PEDro, MEDLINE, Embase, Cochrane Library, and Scopus databases from inception to May 2020. Studies were eligible if participants underwent total knee arthroplasty after two or more weeks of preoperative sensorimotor training. A meta-analysis compared the effects of such interventions with standard care before and after surgery using standardized mean differences (SMD) with 95 % confidence interval (CI). Functional outcome was the primary measure. Balance, pain, and quality of life were also outcomes of interest.ResultsOf the 384 items identified, 7 met the inclusion criteria, and 332 participants were assessed. There was limited evidence suggesting that preoperative sensorimotor training enhanced self-reported function (SMD, 0.89; 95 % CI, 0.16–1.62), functional performance (SMD, 0.56; 95 % CI, 0.19 to 0.93), or knee function (SMD = 0.22–1.05) compared with conventional care. Moderate quality evidence suggested that benefits were only maintained in terms of functional performance up to 3 months after surgery (SMD = 0.37; 95 % CI, 0.13 to 0.62). The outcome was similar after one year.SignificanceCompared with conventional care, preoperative sensorimotor training may enhance early postoperative functional recovery, with no additional benefits on balance, knee function, or pain. The outcome is the same one year after surgery, regardless of whether such training is implemented. Further investigation is needed to determine whether sensorimotor training may be a feasible conservative treatment for severe knee osteoarthritis.  相似文献   
148.
Breast cancer characteristics obtained at the time of diagnosis are important for setting the basic strategy of the treatment. Reliability of preoperative investigation differs for various features of the disease. The aim of this study was to ascertain the agreements and differences between preoperative and postoperative values.  相似文献   
149.
《Clinical neurophysiology》2021,132(12):2948-2958
ObjectiveCerebral spatiotemporal dynamics of visual naming were investigated in epilepsy patients undergoing stereo-electroencephalography (SEEG) monitoring.MethodsBrain networks were defined by Parcel-Activation-Resection-Symptom matching (PARS) approach by matching high-gamma (50–150 Hz) modulations (HGM) in neuroanatomic parcels during visual naming, with neuropsychological outcomes after resection/ablation of those parcels. Brain parcels with >50% electrode contacts simultaneously showing significant HGM were aligned, to delineate spatiotemporal course of naming-related HGM.ResultsIn 41 epilepsy patients, neuroanatomic parcels showed sequential yet temporally overlapping HGM course during visual naming. From bilateral occipital lobes, HGM became increasingly left lateralized, coursing through limbic system. Bilateral superior temporal HGM was noted around response time, and right frontal HGM thereafter. Correlations between resected/ablated parcels, and post-surgical neuropsychological outcomes showed specific regional groupings.ConclusionsConvergence of data from spatiotemporal course of HGM during visual naming, and functional role of specific parcels inferred from neuropsychological deficits after resection/ablation of those parcels, support a model with six cognitive subcomponents of visual naming having overlapping temporal profiles.SignificanceCerebral substrates supporting visual naming are bilaterally distributed with relative hemispheric contribution dependent on cognitive demands at a specific time. PARS approach can be extended to study other cognitive and functional brain networks.  相似文献   
150.
《Clinical neurophysiology》2021,132(2):568-580
ObjectiveFast Oscillations (FO) >40 Hz are a promising biomarker of the epileptogenic zone (EZ). Evidence using scalp electroencephalography (EEG) remains scarce. We assessed if electrical source imaging of FO using 256-channel high-density EEG (HD-EEG) is useful for EZ identification.MethodsWe analyzed HD-EEG recordings of 10 focal drug-resistant epilepsy patients with seizure-free postsurgical outcome. We marked FO candidate events at the time of epileptic spikes and verified them by screening for an isolated peak in the time-frequency plot. We performed electrical source imaging of spikes and FO within the Maximum Entropy of the Mean framework. Source localization maps were validated against the surgical cavity.ResultsWe identified FO in five out of 10 patients who had a superficial or intermediate deep generator. The maximum of the FO maps was localized inside the cavity in all patients (100%). Analysis with a reduced electrode coverage using the 10–10 and 10–20 system showed a decreased localization accuracy of 60% and 40% respectively.ConclusionsFO recorded with HD-EEG localize the EZ. HD-EEG is better suited to detect and localize FO than conventional EEG approaches.SignificanceThis study acts as proof-of-concept that FO localization using 256-channel HD-EEG is a viable marker of the EZ.  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