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   2587篇
  免费   112篇
  国内免费   10篇
耳鼻咽喉   97篇
儿科学   47篇
妇产科学   24篇
基础医学   312篇
口腔科学   18篇
临床医学   331篇
内科学   562篇
皮肤病学   21篇
神经病学   150篇
特种医学   63篇
外科学   455篇
综合类   28篇
预防医学   75篇
眼科学   41篇
药学   235篇
中国医学   16篇
肿瘤学   234篇
  2022年   18篇
  2021年   42篇
  2019年   27篇
  2018年   34篇
  2017年   26篇
  2016年   20篇
  2015年   39篇
  2014年   56篇
  2013年   57篇
  2012年   90篇
  2011年   106篇
  2010年   64篇
  2009年   55篇
  2008年   105篇
  2007年   90篇
  2006年   100篇
  2005年   91篇
  2004年   92篇
  2003年   92篇
  2002年   107篇
  2001年   109篇
  2000年   88篇
  1999年   89篇
  1998年   30篇
  1997年   25篇
  1996年   19篇
  1995年   19篇
  1994年   17篇
  1992年   53篇
  1991年   58篇
  1990年   53篇
  1989年   80篇
  1988年   49篇
  1987年   58篇
  1986年   77篇
  1985年   93篇
  1984年   41篇
  1983年   45篇
  1982年   22篇
  1981年   18篇
  1979年   41篇
  1978年   29篇
  1977年   19篇
  1976年   18篇
  1975年   25篇
  1974年   26篇
  1973年   22篇
  1970年   29篇
  1969年   25篇
  1968年   18篇
排序方式: 共有2709条查询结果,搜索用时 15 毫秒
11.
Summary The pathogenesis of diabetic cardiomyopathy is unknown. The synergistic, or enhanced, effect of hypertension on pathological changes in the heart of diabetic patients has been highly suspected. The purpose of this study was to evaluate the myocardial changes related to diabetes mellitus with and without hypertension, using biopsy specimens. We examined the ultrastructural changes in biopsy specimens of the endomyocardium obtained from 25 patients. They were divided into four groups: controls without hypertension or diabetes mellitus (n=6), and patient with hypertension (n=3), diabetes mellitus (n=8), and diabetes with hypertension (n=8). The diabetic patients showed nearly normal or mildly depressed systolic left ventricular function. Ultrastructural pictures were analyzed for thickening of the capillary basement membrane, presence of toluidine blue-positive materials (i.e., materials showing metachromasia) in the myocytes, size of myocytes, and interstitial fibrosis. The thickening of the capillary basement membrane, the accumulation of toluidine blue-positive materials, and interstitial fibrosis were all significantly greater in the patients with diabetes mellitus compared to the control subjects. The myocytes tended to be small (cell atrophy) in the diabetes group. Although these pathological changes in the heart were characteristic of diabetic patients, irrespective of the presence or absence of hypertension, the presence of hypertension increased the pathological changes of myocardial cells as well as abnormality in the capillary vessels in patients with diabetes mellitus. Alterations in the myocardial cells and capillaries, caused by diabetes mellitus, may lead to myocardial cell injury and interstitial fibrosis and, ultimately, to ventricular systolic and diastolic dysfunction, especially when the diabetes is accompanied by hypertension.  相似文献   
12.
Kidneys of 64 Afghan pikas (Ochotona rufescens rufescens) were examined histologically. Seven of 21 males and two of 21 females over 6 months of age had a cuboidal epithelium lining of the parietal layer of Bowman's capsule.  相似文献   
13.
J Tamaoki  A Chiyotani  E Tagaya  N Sakai    K Konno 《Thorax》1994,49(6):545-548
BACKGROUND--Anticholinergic bronchodilator drugs improve lung function in chronic bronchitis but less is known of their effects on the volume and physical properties of sputum in conditions associated with excessive airway secretions. This study examines the effects of the regular use of oxitropium bromide in such patients. METHODS--The study was conducted in a parallel, double blind, placebo controlled fashion. Patients were divided into two groups: the first group (n = 17) received oxitropium bromide from a metered dose inhaler (two puffs three times daily; 100 micrograms/puff) for eight weeks, and the second group (n = 16) received placebo. Lung function was measured as forced expiratory volume in one second (FEV1) and vital capacity. In evaluating airway secretion, daily amount of expectorated sputum, percentage solid composition, viscoelastic properties including elastic modulus and dynamic viscosity, and sputum microbiology were determined. RESULTS--Oxitropium bromide increased FEV1 and decreased the mean (SE) sputum production from 61(4) to 42(3) g/day after treatment, whereas placebo had no effect. Bacterial density and sputum flora were unchanged, but solid composition and elastic modulus increased from 2.52(0.43)% to 3.12(0.34)%, and 68(12) dyne/cm2, respectively, in the group taking oxitropium bromide. CONCLUSIONS--Regular treatment with oxitropium bromide not only improves airflow limitation but also reduces sputum production, probably through the inhibition of both mucus secretion and water transport, the latter component being predominant.  相似文献   
14.
The condition of a 51-year-old man was complicated with empyema and bronchopleural fistula (BPF) after left upper lobectomy and thoracoplasty for pulmonary aspergillosis. On the postoperative day (POD) 12, the opened bronchial stump was directly closed and covered with a pedicled pectoralis major muscle flap. On POD 66, an open-window thoracostomy was done, because of empyema with Pseudomonas aeruginosa. Two years later, we could fill the empyema cavity, and close the multiple BPFs with the transposition of a modified pedicled musculocutaneous (MC) flap and the additional thoracoplasty to gain good quality of life. Although the MC flap was a proximal part of the latissimus dorsi muscle, which was dissected along the posterolateral incision of the first operation, it could be successfully transplanted to cover the BPFs in the open-window. In some patients with a small open-window on the upper anterior chest wall, the pedicled proximal latissimus dorsi MC flap may be very useful for treating persistent BPFs even after a standard posterolateral incision.  相似文献   
15.
Hepatic angiomyolipoma is a rare tumor composed of spindle-shaped and epithelioid smooth muscle cells, adipose tissue, and proliferating blood vessels. We report the first documented case of this tumor developing in a patient with ulcerative colitis. A solitary tumor (7.5×7.5×7cm) was detected in the left lateral segment of the liver and a left hepatic lobectomy was performed. The diagnosis of angiomyolipoma was confirmed by a pathological examination. We also review the literature on previously reported cases of hepatic angiomyolipoma.  相似文献   
16.
Effects on human performance of remoxipride (RX), an antipsychotic drug of substituted benzamide structure, were studied in a randomized double-blind crossover trial where 12 young healthy volunteers took at 1 week intervals single oral doses of placebo or remoxipiride 100 mg both alone and in combination with 15 mg diazepam (DZ) or 0.8 g/kg ethanol (EtOH). Objective (digit symbols, tracking, choice reaction, flicker fusion, Maddox wing, body balance, memory) and subjective (visual analogue scales, questionnaire) tests were administered at baseline and 1.5, 3, 4.5 and 6 h post-treatment.  相似文献   
17.
Summary Monoclonal antibodies (MRC OX-6 and OX-17) recognized three types of cells expressing Ia antigen during the course of acute experimental allergic encephalomyelitis (EAE) in rats. In earlier stages of the disease, in animals with or without paralysis, Ia antigens were mostly localized to subarachnoidal and perivascular lymphocytic and histiocytic cell infiltrates, possibly serving as antigen-presenting cells. On the other hand, in convalescent rats, Ia antigens were expressed in a large number of cells with dendritic processes heavily populating the spinal gray matter. The appearance of these Ia-expressing cells in the convalescent stage coincided with the development of degenerating axon terminals in the spinal gray matter. These Ia-expressing cells possessed morphological features characteristic of microglia and were positive for ML-1 lectin but did not express glial fibrillary acidic protein. Immune electron microscopy disclosed the presence of Ia reaction products in the Golgi apparatus, endoplasmic reticulum and plasma membrane of these cells with dendritic processes, indicating active synthesis of Ia molecules in microglia. In addition, Ia antigens were localized to the cells with ultrastructural features of macrophages. Thus, Ia-expressing cells in EAE seems to play dual roles: the induction of immunological reactions during earlier stages and the participation in reparative processes during convalescence.Supported by Grants-in-aid from the Ministry of Health and Welfare for Intractable Neuroimmunological Diseases and from the Ministry of Education, Science and Culture (Project 61570380 to HK)  相似文献   
18.
Chronic active Epstein-Barr virus infection (CAEBV) is a syndrome that takes diverse clinical courses and is often associated with lymphoproliferative disorders of T/natural killer (NK)-cell lineage. We describe a patient with CAEBV associated with persistent pharyngeal ulcer, and with subsequent nasal T/NK-cell lymphoma in her neck lymph nodes and nasopharynx. Immunophenotyping of lymphoid cells showed that the lineage of Epstein-Barr virus (EBV)-positive cells in the patient was of NK-cell origin. By means of high-dose recombinant interleukin-2, we established an EBV-positive cell line of NK-cell lineage from her peripheral blood. Southern blot analysis for the number of terminal repeat sequences of EBV detected three NK-cell clones in the patient's lymph node. One of these clones was identical to the established cell line but was not observed in the pharyngeal ulcer, while the other two clones were present in the pharyngeal ulcer. These results suggest that the patient had expansion of the three NK-cell clones, one of which had proliferative capacity in vitro and was involved in the formation of the lymphoma. Moreover, the results suggest that the proliferative capacity of EBV-positive cells can be variable even in a single patient, and this variability may explain the clinical diversity in CAEBV.  相似文献   
19.
The highly potent and selective anti-DNA virus agent (S)-9-(3-hydroxy-2-phosphonylmethoxypropyl)adenine [(S)-HPMPA] was found to inhibit in vitro the replication of a number of clinical varicella-zoster virus strains within the concentration range of 0.63—5.7 ng/ml. With a mean 50 % inhibitory concentration of 1.8 ng/ml and selectivity index of 29000, (S)-HPMPA is one of the most potent and most selective varicella-zoster virus inhibitors discovered to date.  相似文献   
20.
A new mutation in the serine-threonine klnase domain of the transforming growth factor β type II receptor (TGFpRII) was found in a case of diffuse, B cell non-Hodgkin's lymphoma of the stomach. A mfssense mutation (ACA to GCA, Thr to Ala) was detected In exon 5, and a wild type allele was also present. This Is the first naturally occurring mutation in the klnase domain of this gene identified in human primary lymphoma. The replication error at three loci was negative, and the poly A tract of exon 3, which is frequently a target of mismatch repair genes, was intact. Malignant lymphoma of B cell origin in the stomach Is an addition to an expanding catalogue of tumors with TGFβRII alterations, and the biological sequelae of the change in the functional domain and the clinical characteristics of the patient in this study are intriguing.  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