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   4524篇
  免费   202篇
  国内免费   31篇
耳鼻咽喉   51篇
儿科学   98篇
妇产科学   31篇
基础医学   686篇
口腔科学   118篇
临床医学   237篇
内科学   1154篇
皮肤病学   167篇
神经病学   395篇
特种医学   210篇
外科学   806篇
综合类   29篇
预防医学   55篇
眼科学   19篇
药学   263篇
中国医学   13篇
肿瘤学   425篇
  2023年   25篇
  2022年   48篇
  2021年   68篇
  2020年   55篇
  2019年   64篇
  2018年   89篇
  2017年   56篇
  2016年   89篇
  2015年   71篇
  2014年   108篇
  2013年   121篇
  2012年   227篇
  2011年   244篇
  2010年   152篇
  2009年   128篇
  2008年   245篇
  2007年   260篇
  2006年   232篇
  2005年   257篇
  2004年   268篇
  2003年   257篇
  2002年   305篇
  2001年   104篇
  2000年   129篇
  1999年   100篇
  1998年   58篇
  1997年   58篇
  1996年   35篇
  1995年   51篇
  1994年   41篇
  1993年   43篇
  1992年   73篇
  1991年   65篇
  1990年   72篇
  1989年   60篇
  1988年   51篇
  1987年   53篇
  1986年   46篇
  1985年   32篇
  1984年   37篇
  1983年   26篇
  1981年   21篇
  1980年   18篇
  1979年   19篇
  1977年   17篇
  1973年   16篇
  1972年   20篇
  1970年   17篇
  1967年   16篇
  1966年   15篇
排序方式: 共有4757条查询结果,搜索用时 15 毫秒
71.
BackgroundThe disparity of overall diet quality by personal educational attainment has been a public issue. However, it remains unknown which food groups contribute to the disparity. This cross-sectional study assesses which food groups explain associations between education and overall diet quality in Japanese women.MethodsA total of 3,788 middle-aged (mean age, 47.7 years) and 2,188 older women (mean age, 74.4 years), who lived in 47 prefectures in Japan, provided data on their education (low, middle, and high) and dietary intakes from a diet history questionnaire. A diet quality score (possible score 0–70) was calculated based on seven food components. Mean diet quality scores, with adjustment for lifestyle and neighborhood variables, were estimated by education using a general linear model, and Dunnett’s multiple comparison was conducted. Additionally, mean scores of each food component were estimated by education and compared using the same manner.ResultsAfter adjustment for lifestyle and neighborhood variables, mean diet quality score of high or middle education was higher than low education for both generations. Middle-aged women with high and middle education had higher scores of ‘milk’, ‘snacks, confection, and beverages’, ‘fruits’, and ‘vegetable dishes’ than those with low education. Older women with high and middle education had higher scores of ‘sodium from seasonings’ and ‘fruits’ than those with low education.ConclusionsThis study suggests that positive associations between education and diet quality are explained by different food groups in middle-aged and older Japanese women, which are independent of lifestyle and neighborhood variables.Key words: education, diet quality, Japanese  相似文献   
72.
Gonadotropin-inhibitory hormone (GnIH) is a hypothalamic dodecapeptide (SIKPSAYLPLRF-NH(2)) that directly inhibits gonadotropin synthesis and release from quail pituitary. The action of GnIH is mediated by a novel G-protein coupled receptor. This gonadotropin-inhibitory system may be widespread in vertebrates, at least birds and mammals. In these higher vertebrates, histological evidence suggests contact of GnIH immunoreactive axon terminals with GnRH neurons, thus indicating direct regulation of GnRH neuronal activity by GnIH. In this study we investigated the interaction of GnIH and GnRH-I and -II neurons in European starling (Sturnus vulgaris) brain. Cloned starling GnIH precursor cDNA encoded three peptides that possess characteristic LPXRF-amide (X = L or Q) motifs at the C termini. Starling GnIH was further identified as SIKPFANLPLRF-NH(2) by mass spectrometry combined with immunoaffinity purification. GnIH neurons, identified by in situ hybridization and immunocytochemistry (ICC), were clustered in the hypothalamic paraventricular nucleus. GnIH immunoreactive fiber terminals were present in the external layer of the median eminence in addition to the preoptic area and midbrain, where GnRH-I and GnRH-II neuronal cell bodies exist, respectively. GnIH axon terminals on GnRH-I and -II neurons were shown by GnIH and GnRH double-label ICC. Furthermore, the expression of starling GnIH receptor mRNA was identified in both GnRH-I and GnRH-II neurons by in situ hybridization combined with GnRH ICC. The cellular localization of GnIH receptor has not previously been identified in any vertebrate brain. Thus, GnIH may regulate reproduction of vertebrates by directly modulating GnRH-I and GnRH-II neuronal activity, in addition to influencing the pituitary gland.  相似文献   
73.
A 54-year old man was admitted with general fatigue, muscle weakness and dyspnea on effort. Medical examinations led to a diagnosis of small cell lung carcinoma (SCLC) with Lambert-Eaton myasthenic syndrome (LEMS). Marked improvement of SCLC and symptoms of LEMS were recognized twice during chemoradiotherapy. On his third admission, he showed muscle weakness, dysaethesia, and neurodysfunction of the bladder and rectum. We initially considered these symptoms to be due to spinal metastasis because MRI findings showed multiple spinal metastases. However, electoromyogram and nerve conduction study demonstrated that his muscle weakness resulted from LEMS though dysethesia and neurodysfunction of bladder and rectum were caused by spinal metastasis. We believe that it is important to perform electomyogram and nerve conduction studies, not only radiographic findings, to detect the "hidden" symptoms of LEMS.  相似文献   
74.
A 69-year-old woman underwent percutaneous coronary intervention for a severe stenotic lesion in the bifurcation of the mid-left anterior descending artery and first diagonal branch. A single stent was implanted into the left anterior descending artery. After the stent strut was dilated by balloon inflation in the diagonal branch, dissection occurred at the ostium of the diagonal branch and resulted in side branch occlusion due to hematoma. Bailout stenting was performed in the diagonal branch, but thrombus projection occurred in the left anterior descending artery. Aspiration, balloon inflation and thrombolytic therapy were performed, but distal embolism developed. This case illustrates that thrombus projection caused by stenting in a side branch may occur as a rare complication in percutaneous coronary intervention.  相似文献   
75.
A 54-year old man was admitted to our hospital because of high fever, productive cough and purpura in both legs in June 2005. Urinalysis showed microscopic hematuria and proteinuria. Chest radiograph showed consolidation of right upper field. Because acid-fast bacilli and polymerase chain reaction test for Mycobacterium tuberculosis were positive in bronchial lavage fluid, we made a diagnosis of pulmonary tuberculosis, and prescribed antituberculosis therapy with isoniazid, rifampicin, ethambutol and pyrazinamide. In addition, anaphylactoid purpura was diagnosed by skin biopsy. In July 2005, renal function was deteriorated and nephrosis appeared. We treated with corticosteroid in addition to antituberculosis therapy. His symptoms and renal dysfunction improved. We report a rare case of an anaphylactoid purpura following occurence of pulmonary tuberculosis.  相似文献   
76.
BACKGROUND: The use of methylene blue chromoendoscopy in the diagnosis of specialized intestinal metaplasia in short-segment Barrett's esophagus is controversial. This study evaluated the use of magnifying endoscopy with methylene blue for this purpose. METHODS: A total of 30 patients (21 men, 9 women; median age 61 years, range 32-79 years) with short lengths of columnar-lined esophagus were enrolled in a prospective trial of magnifying endoscopy with methylene blue in which the appearance after methylene blue staining was used to target biopsy specimens. Patients were screened for Helicobacter pylori infection, and only those without infection were enrolled (because many Japanese patients have pan-gastritis caused by H pylori infection, and intestinal metaplasia distal to the squamocolumnar junction may be secondary to H pylori-induced gastritis). All biopsy specimens were stained with H and E; MUC2 immunostaining was used to identify specialized intestinal metaplasia. RESULTS: Thirty patients with short-segment columnar-lined esophagus underwent magnifying endoscopy with methylene blue. Ninety-three biopsy specimens were obtained, 33 from methylene blue-stained areas and 60 from unstained areas, each about 7 mm from the marginal edge of stained areas. Specialized intestinal metaplasia was confirmed in biopsy specimens from 28 of the 33 stained areas (sensitivity 84.8%); in biopsy specimens from 55 of the 60 unstained areas, specialized intestinal metaplasia was not found (specificity 91.7%). In magnified views of methylene blue-positive areas, a tubular, cavernous, or elliptical pattern was seen. Sixteen of 21 men (76.2%) and 3 of 9 women had specialized intestinal metaplasia, and short-segment Barrett's esophagus was diagnosed in these patients. Even in patients with less than 1 cm of columnar-lined esophagus, 8 of 10 stained areas contained specialized intestinal metaplasia (sensitivity 80%) and 23 of 24 unstained areas did not (specificity 95.8%). Six of 12 patients (50%) with less than 1 cm of columnar-lined esophagus had specialized intestinal metaplasia. In total, 19 of 30 patients had specialized intestinal metaplasia. CONCLUSIONS: Magnifying endoscopy with methylene blue selectively detects specialized intestinal metaplasia within short-segment columnar-lined esophagus.  相似文献   
77.
To examine the role of thyroid hormones in the seasonal breeding cycle in Japanese monkeys (Macaca fuscata fuscata), sexually mature females were thyroidectomized (n=6) in early December, during the midbreeding season, or they received sham operations (n=4). They were housed indoors individually, and blood samples were collected two to three times a week to monitor gonadotropin and gonadal steroid hormone secretions. Control monkeys exhibited ovulatory cycles during the breeding season. The mean dates of onset and end of the ovulatory cycles were October 22±13 d and February 25±14 d, respectively. These dates coincided well with those of our colonies under captivity. By contrast, three of the six thyroidectomized monkeys terminated ovulatory cycles immediately after operations; the remaining three monkeys ovulated only once or twice after thyroid removal. The mean dates of onset and end of the ovulatory cycles of thyroidectomized monkeys were October 18±4 d and December 31±4 d, respectively. This was a significantly earlier termination of the ovulatory cycles than in controls. Mean concentrations of plasma thyroxine of control monkeys were maintained throughout the experimental period, whereas plasma thyroxine concentrations of thyroidectomized monkeys decreased abruptly to undetectable levels. Thyroidectomized monkeys exhibited significantly higher levels of plasma prolactin (PRL) than controls. Moreover, even in control monkeys, plasma PRL increased during the transition out of the breeding season. These results suggest that thyroid hormones play an important role in the regulation of ovulatory cycles in Japanese monkeys, directory or indirectly, possibly by mediating the changes of PRL secretion.  相似文献   
78.
We report on a case of metastatic adenocarcinoma of liver that was removed and examined histochemically after microwave coagulation therapy (MCT). The patient was a 65-year-old woman who had a metastatic tumor in the liver (S3) after high anterior resection due to a rectal adenocarcinoma and received MCT against the tumor. One month after MCT, multiple metastatic tumors were detected by abdominal computed tomography (CT) scan. As it was difficult to control them by MCT alone, we performed lateral segmentectomy. To assess the effects of microwave ablation on cellular viability of metastatic tumor, we used enzyme histochemistry for acid phosphatase (AcP), which is positive in macrophages infiltrating in the tumor. In a part of the ablated area of resected liver, there was remaining neoplastic tissue of which the morphology was maintained in H&E staining. This was found to be microwave-fixed non-viable tissue because no enzyme activity of AcP was detected in the infiltrating macrophages. This case report suggests that enzyme histochemistry was useful to assess the effect of MCT, enabling us to distinguish fixed cells from viable cells.  相似文献   
79.
80.
Objective: To investigate the potential beneficial effects of guideline-based pharmacological therapy on pulmonary function and quality of life (QOL) in Japanese chronic obstructive pulmonary disease (COPD) patients without prior treatment.

Research design and methods: Multicenter survey, open-label study of 49 Japanese COPD patients aged ≥ 40 years; outpatients with >10 pack years of smoking history; ratio of forced expiratory volume in 1 s (FEV1)/forced vital capacity (FVC) < 70%; predicted FEV1 < 80%; treated with bronchodilators and/or inhaled corticosteroids as maintenance therapy until week 48.

Main outcome measures: The primary endpoint was change in pulmonary function (trough FEV1, trough FVC); secondary endpoints were QOL and physical activity at 48 weeks after initiation of therapy.

Results: Airway reversibility was confirmed in untreated patients. Significant changes over time were not observed for FEV1 and FVC, indicating lung function at initiation of treatment was maintained during the observation period. COPD assessment test scores showed statistical and clinical improvements. Cough, sputum, breathlessness, and shortness of breath were significantly improved.

Conclusions: Lung function and QOL of untreated Japanese COPD patients improved and improvements were maintained by performing a therapeutic intervention that conformed to published guidelines.  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