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   1529篇
  免费   108篇
  国内免费   9篇
耳鼻咽喉   34篇
儿科学   28篇
妇产科学   11篇
基础医学   199篇
口腔科学   20篇
临床医学   133篇
内科学   492篇
皮肤病学   21篇
神经病学   89篇
特种医学   55篇
外科学   262篇
综合类   16篇
预防医学   29篇
眼科学   23篇
药学   117篇
中国医学   3篇
肿瘤学   114篇
  2022年   19篇
  2021年   29篇
  2020年   12篇
  2019年   27篇
  2018年   34篇
  2017年   28篇
  2016年   35篇
  2015年   26篇
  2014年   30篇
  2013年   39篇
  2012年   68篇
  2011年   79篇
  2010年   35篇
  2009年   46篇
  2008年   75篇
  2007年   85篇
  2006年   85篇
  2005年   88篇
  2004年   91篇
  2003年   99篇
  2002年   98篇
  2001年   42篇
  2000年   60篇
  1999年   63篇
  1998年   24篇
  1997年   16篇
  1996年   14篇
  1995年   12篇
  1994年   15篇
  1993年   14篇
  1992年   11篇
  1991年   25篇
  1990年   10篇
  1989年   17篇
  1988年   13篇
  1987年   15篇
  1986年   8篇
  1985年   19篇
  1984年   10篇
  1983年   11篇
  1982年   7篇
  1979年   10篇
  1978年   8篇
  1977年   7篇
  1976年   6篇
  1974年   9篇
  1973年   10篇
  1972年   13篇
  1970年   9篇
  1969年   9篇
排序方式: 共有1646条查询结果,搜索用时 15 毫秒
71.
A double-blind, parallel-group, placebo-controlled trial was performed on 50- to 80-year-old Japanese men and women diagnosed with mild cognitive impairment in order to examine the efficacy of oral administration of Yamabushitake (Hericium erinaceus), an edible mushroom, for improving cognitive impairment, using a cognitive function scale based on the Revised Hasegawa Dementia Scale (HDS-R). After 2 weeks of preliminary examination, 30 subjects were randomized into two 15-person groups, one of which was given Yamabushitake and the other given a placebo. The subjects of the Yamabushitake group took four 250 mg tablets containing 96% of Yamabushitake dry powder three times a day for 16 weeks. After termination of the intake, the subjects were observed for the next 4 weeks. At weeks 8, 12 and 16 of the trial, the Yamabushitake group showed significantly increased scores on the cognitive function scale compared with the placebo group. The Yamabushitake group's scores increased with the duration of intake, but at week 4 after the termination of the 16 weeks intake, the scores decreased significantly. Laboratory tests showed no adverse effect of Yamabushitake. The results obtained in this study suggest that Yamabushitake is effective in improving mild cognitive impairment.  相似文献   
72.
Adiponectin, also referred to as AdipoQ or ACRP30, is a plasma protein produced and secreted exclusively from adipose tissue. The protein contains a collagen-like domain and a C1q-like globular domain. A protease-generated globular segment enhances fatty acid oxidation in muscles, thereby modulating lipid and glucose metabolism. Plasma adiponectin levels are inversely correlated with the severity of insulin resistance. A recent genome-wide scan study mapped a susceptibility locus for type 2 diabetes and the metabolic syndrome to chromosome 3q27, where the adiponectin gene is located. Here, we screened Japanese patients with type 2 diabetes and age- and BMI-matched nondiabetic control subjects for mutations in adiponectin gene. We identified four missense mutations (R112C, I164T, R221S, and H241P) in the globular domain. Among these mutations, the frequency of I164T mutation was significantly higher in type 2 diabetic patients than in age- and BMI- matched control subjects (P < 0.01). Furthermore, plasma adiponectin concentrations of subjects carrying I164T mutation were lower than those of subjects without the mutation. All the subjects carrying I164T mutation showed some feature of metabolic syndrome, including hypertension, hyperlipidemia, diabetes, and atherosclerosis. Our findings suggest that I164T mutation is associated with low plasma adiponectin concentration and type 2 diabetes.  相似文献   
73.
74.
75.
DNA methylation status correlates with clinical outcomes of anti‐epidermal growth factor receptor (EGFR) treatment. There is a strong need to develop a simple assay for measuring DNA methylation status for the clinical application of drug selection based on it. In this study, we collected data from 186 patients with metastatic colorectal cancer (mCRC) who had previously received anti‐EGFR treatment. We modified MethyLite to develop a novel assay to classify patients as having highly methylated colorectal cancer (HMCC) or low‐methylated colorectal cancer (LMCC) based on the methylation status of 16 CpG sites of tumor‐derived genomic DNA in the development cohort (n = 30). Clinical outcomes were then compared between the HMCC and LMCC groups in the validation cohort (n = 156). The results showed that HMCC had a significantly worse response rate (4.2% vs 33.3%; P = .004), progression‐free survival (median: 2.5 vs 6.6 mo, P < .001, hazard ratio [HR] = 0.22), and overall survival (median: 5.6 vs 15.5 mo, P < .001, HR = 0.23) than did LMCC in patients with RAS wild‐type mCRC who were refractory or intolerable to oxaliplatin‐ and irinotecan‐based chemotherapy (n = 101). The DNA methylation status was an independent predictive factor and a more accurate biomarker than was the primary site of anti‐EGFR treatment. In conclusion, our novel DNA methylation measurement assay based on MethyLight was simple and useful, suggesting its implementation as a complementary diagnostic tool in a clinical setting.  相似文献   
76.
77.
Endoscopic submucosal dissection (ESD) has emerged as a novel technique for achieving en bloc resection for superficial neoplasms limited to the mucosa. ESD was originally developed in Japan as a method of endoscopic resection of superficial gastric cancers. In our hospital, ESD has been used concurrently in other parts of the gastrointestinal tract, including the esophagus and colorectum from the beginning of its development. However, ESD in the duodenum is considered more challenging than other parts. From August 2005 to March 2008, a total of 15 superficial duodenal neoplastic lesions in 14 patients were treated with endoscopic resection. Of these, nine underwent ESD. We report our experience with duodenal ESD with a combination of ST hood and hook knife.  相似文献   
78.
BACKGROUND: The usefulness of sputum Gram stain and culture in guiding microbiological diagnosis of community-acquired pneumonia (CAP) is controversial. We evaluated the role of sputum examination at a university teaching hospital. MATERIAL/METHODS: Three hundred forty-seven adult patients with CAP were enrolled in this study. Before administering antibiotic therapy, sputum was collected and its quality evaluated. Samples were gram stained and those of good quality were assessed for a predominant morphotype. RESULTS: Sputum samples were obtained from 216 patients (62%), and of these 124 (57%) samples were good quality and 80 (65%) showed a predominant morphotype. Sputum culture yielded a causative organism in 70 (88%) of the 80 samples with a predominant morphotype. In the cases of patients who had received previous antibiotic treatment, a good quality samples showing a predominant morphotype and positive culture was less frequently obtained from than from those who had not (p<0.0001). The sensitivity and specificity of the gram-positive diplococci identification in the sputum culture of S. pneumoniae were 68.2% and 93.8%, respectively, and the sensitivity and specificity of the gram-negative coccobacilli identification in the sputum culture of H. influenzae were 76.2% and 100%, respectively. CONCLUSIONS: Gram stain of sputum samples was useful in guiding microbiological diagnosis of CAP in 23% of patients. The Gram stain and culture of sputum samples obtained from patients who have received antibiotic treatment was unreliable. The presence of gram-positive diplococci and gram-negative coccobacilli was highly specific for the culture of S. pneumoniae and H. influenzae, respectively.  相似文献   
79.
We conducted a prospective study to evaluate the significanceof serum neuron-specific enolase (NSE) as a predictor of relapseof small cell lung cancer (SCLC). Patients entered into thestudy were drawn from those who had shown a complete or partialresponse to first-line chemotherapy with a concurrent declinein the NSE level to less than 10 ng/ml. When the serum NSE levelincreased to more than 15 ng/ml, the patient was restaged onthe basis of clinical, radiological, and bronchoscopic examinations.During the period from August 1988 to December 1990, 57 patientswith SCLC were enrolled and followed up until May 1992; Of thesepatients, 45 had clinical relapses, and 14 (31%) of them showeda clear elevation of the serum NSE level prior to the clinicalrecognition of relapse. Although one false-positive case wasnoted, this involved only a transient elevation of the NSE level.In patients who showed increased NSE levels, the relapses occurredin more difficult to detect silent sites such as the adrenalgland, liver, and deep lymph nodes. In addition, the percentageof patients demonstrating high NSE levels who were able to benefitfrom salvage chemotherapy was higher than for those who didnot (P<0.05). Our results indicate that serial NSE measurementsare useful for the early prediction of SCLC relapse and shouldhelp to facilitate early administration of salvage chemotherapyfor affected patients.(P<0.05)  相似文献   
80.
False negative rates were compared in two screening modalities, physical examination with or without mammography, in an intervention study for women aged over 50 in Miyagi Prefecture. Thirty-five breast cancers were detected in 12,515 subjects who participated in the trial consisting of physical examination and mammography, whereas 44 breast cancers were detected in 50,105 subjects who received physical examination alone, so that the detection rates were 0.28% and 0.09%, respectively. Among 50,061 subjects who received physical examination alone, 8 women were diagnosed as having breast cancer within 12 months after the screening, while only one of 12,480 screenees receiving the combined modality was so diagnosed, implying false negative rates of 15.4% and 2.8%, respectively. When the screening sensitivity in the combined system was analyzed according to each single modality, the false negative rate provided by physical examination with mammography turned out to be 2.8%, significantly lower than that (33.3%) by the physical examination alone. Minimal breast cancers represented 25.7% of all screen-detected cancers in the combined modality, compared with 9.1% in the modality without mammography. The trial thus indicates that physical examination combined with mammography may be an appropriate modality for breast cancer screening in women aged over 50 on the basis of screening sensitivity.  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