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   14129篇
  免费   764篇
  国内免费   97篇
耳鼻咽喉   158篇
儿科学   372篇
妇产科学   378篇
基础医学   1891篇
口腔科学   327篇
临床医学   1403篇
内科学   2890篇
皮肤病学   523篇
神经病学   847篇
特种医学   791篇
外科学   2231篇
综合类   185篇
现状与发展   1篇
一般理论   2篇
预防医学   601篇
眼科学   275篇
药学   1074篇
中国医学   150篇
肿瘤学   891篇
  2023年   90篇
  2022年   249篇
  2021年   421篇
  2020年   197篇
  2019年   271篇
  2018年   418篇
  2017年   300篇
  2016年   349篇
  2015年   445篇
  2014年   654篇
  2013年   668篇
  2012年   1047篇
  2011年   1015篇
  2010年   609篇
  2009年   486篇
  2008年   810篇
  2007年   790篇
  2006年   747篇
  2005年   737篇
  2004年   651篇
  2003年   526篇
  2002年   498篇
  2001年   428篇
  2000年   398篇
  1999年   321篇
  1998年   149篇
  1997年   123篇
  1996年   123篇
  1995年   98篇
  1994年   89篇
  1993年   53篇
  1992年   127篇
  1991年   113篇
  1990年   106篇
  1989年   77篇
  1988年   74篇
  1987年   82篇
  1986年   69篇
  1985年   66篇
  1984年   40篇
  1983年   33篇
  1981年   26篇
  1980年   27篇
  1979年   33篇
  1977年   33篇
  1976年   29篇
  1975年   27篇
  1974年   28篇
  1973年   26篇
  1972年   30篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
992.
The phenomenon of tumor-associated tissue eosinophilia (TATE) is seen in some cases of nasopharyngeal carcinoma (NPC) and is characterized by the eosinophils breaking through the vascular wall and pervading the tumor stroma. The margination and trans-endothelial migration of eosinophils in a typical inflammatory reaction depend on the activating effects of certain cytokines and the expression of adhesion molecules on the eosinophils and endothelial cells. In order to investigate whether the adhesion molecules and activating cytokines play a role in eosinophil tumor infiltration, we measured the serum levels of 3 adhesion molecules, intercellular adhesion molecule-1, E-selectin and vascular cell adhesion molecule-1, and 2 cytokines, IL-3 and IL-5, in 60 NPC patients and 40 normal healthy subjects. We found that the NPC patients had higher serum levels of all three soluble adhesion molecules than the normal subjects but the levels of adhesion molecules failed to correlate with the TATE phenomenon. The levels of IL-3 and IL-5 appeared not to differ between the NPC and control groups. We postulate that the three soluble adhesion molecules do not play a major role in TATE and that their elevation in serum may be due to local and/or systemic immune responses.  相似文献   
993.
A semi-implantable electromagnetic hearing device (SIMEHD) for sensorineural hearing loss has been developed and tested in animals and limited clinical trial. The authors' electromagnetic transducer, which is the driver of the SIMEHD, when used in reverse mode is applicable to the fabrication of a bioelectronic microphone. Instead of being a driver, it transforms the sound-activated eardrum-ossicular vibration into an electric signal through the NdFeBo magnet implanted on the head of the malleus, interacting in a contactless manner with the electromagnetic coil.  相似文献   
994.
Autoimmune hepatitis   总被引:2,自引:0,他引:2  
Autoimmune hepatitis is one of the causes of chronic progressive liver disease in childhood. Here we report 14 cases with clinical findings, therapeutic management and prognosis, in order to define the course of the disease. Diagnosis of autoimmune hepatitis was done with the presence of at least one of these autoantibodies; antinuclear antibody, smooth muscle antibody, liver-kidney microsomal type 1 antibody, and perinuclear antineutrophilic cytoplasmic antibody. Patients were seen every 3 to 6 months. After doing a complete physical examination, biochemical parameters and autoantibodies determined at each visit. Mean age at diagnosis was 10.9±2.6 years (range, 7–15.5 years) and female to male ratio was 1∶3. Thirteen patients had jaundice and all had high levels of ALT, AST and gammaglobulin. Hepatomegaly was found in 71.4% and splenomegaly in 64.3% of the patients. All patients were classified as type 1 autoimmune hepatitis. Liver biopsies revealed severe active hepatitis with mononuclear cell infiltration in portal areas, piecemeal necrosis. Drug therapy consisted of prednisone (2 mg/kg/day) per oral at the beginning, and addition of azathioprine (1.5 mg/kg/day) per oral at the 3rd-6th month with slow tapering of prednisone in 12 children. Both drugs were started together to two patients. Follow-up period was 30.7±15.6 months (range, 12–72 months). Sustained normalization of ALT could not be obtained with tapering doses of prednisone alone. Decrease in ALT levels did not correlate with disappearance of serum autoantibodies. None of the patients showed decompensation of liver disease. Azathioprine administration is necessary to decrease prednisone dose and to maintain a sustained normal transaminase values.  相似文献   
995.
996.
The effect of poisoning doses of selenium on serum matrix-degrading enzymes activity was investigated in rats intoxicated with selenium. Fifteen animals were receiving orally sodium selenite in a daily dose of 300 microg/kg body weight. Intoxication with selenium was carried out for 10 weeks. The present study revealed significant increase in activities of enzymes involved in the connective tissue matrix metabolism i.e. beta-glucuronidase, N-acetyl-beta-glucosaminidase, elastase and collagen peptidase. There was no change in the cathepsin activity. The relative enzyme activities calculated over protein level resulted in higher values than those found in direct measurements. Serum enzyme activity was increased most for elastase (about 31%) and N-acetyl-beta-glucosaminidase (about 33%) based on activity per gram of protein. The current data indicate that lysosomes are target organelles for selenium toxicity. Generalized increase in lysosomal enzymes activity contributes to the altered metabolism of the connective tissue in selenium-intoxicated animals. The mechanisms that lead to the increase of lysosomal enzymes activity in rats receiving poisoning doses of selenium could be related to biochemical disturbances caused by selenium toxicity.  相似文献   
997.
OBJECTIVES—Some patients with occupational asthma resulting from exposure to reactive dyes have skin reactivity to the causative dyes and specific IgE to reactive dyes have been found in these patients. However, the usefulness of skin prick tests (SPTs) and serological measurement of specific IgE in screening, diagnosis, and monitoring the occupational asthma resulting from exposure to reactive dyes have not yet been assessed. In this study, the clinical validation of SPTs and measurement of specific IgE to vinyl sulphone reactive dyes by enzyme linked immunosorbent assay (ELISA) was evaluated.
METHODS— 42 Patients with occupational asthma from reactive dyes (true positive group) were enrolled. In these the causative reactive dye was confirmed by bronchial challenge test. 93 Asymptomatic factory workers with negative challenge to the reactive dye (true negative group) and 16 unexposed controls with negative challenge to the reactive dye were also enrolled. Skin prick tests were done with 10 mg/ml reactive dye in 0.4% phenol/0.9% saline. IgE specific to reactive dye conjugated to human serum albumin (HSA) was measured with enzyme linked immunosorbent assays (ELISAs).
RESULTS—None of the unexposed controls had a positive response to SPTs. The sensitivity (76.2% v 53.7%), specificity (91.4% v 86.0%), positive predictive value (80.0% v 62.9%), and negative predictive value (89.5% v 80.8%) of SPTs were higher than those of ELISAs. The mean weal size of reaction to reactive dye was weakly correlated with the ELISA optical density of IgE to reactive dye conjugate in patients with occupational asthma from reactive dyes (n=41, r=0.337, p<0.05). In four patients with occupational asthma from reactive dyes and eight control subjects exposed to reactive dye, IgE specific to reactive dye conjugated to HSA was detected with ELISA even though they showed negative skin reactivity. Six patients completely avoided the reactive dye for a mean (SD) 27.8 (10.3) months, IgE specific to reactive dyes decreased in all six patients (p<0.05) during this time.
CONCLUSIONS—Both SPTs and detection of IgE specific to reactive dye in serum samples could be valuable for screening, diagnosis, and monitoring occupational asthma resulting from exposure to reactive dyes. These two tests would complement each other.


Keywords: reactive dye; occupational asthma; skin prick test  相似文献   
998.
999.
Cerebrotendinous xanthomatosis (CTX) is exceptionally rare in the Chinese population. We reported a 31-year-old Chinese male in Hong Kong, who has the characteristic features of cerebrotendinous xanthomatosis including the multiple xanthomas of tendons, mental retardation, bilateral cataracts, cerebellar ataxia and spasticity of the left arm, high concentrations of plasma phytosterols and abnormal MR of brain. On screening the family, two other siblings of 27 and 29 respectively, have tendon xanthomas and high plasma phytosterols. An extensive search of the international medical literature, including the Medline, has revealed only one other case report of cerebrotendinous xanthomatosis in Taiwan. CTX is a potentially treatable disease. It is hoped by alertness, early diagnosis and treatment can be made, and hence prevent further progression of the disease.  相似文献   
1000.
Kidney biopsy is an indispensible procedure for making a pathologic diagnosis of renal diseases by fixing and staining the biopsy specimen. However, it is not a routine procedure to culture the cells from a renal biopsy specimen directly, or to utilize the cultured cells for any kind of diagnostic or functional evaluation. In this study, primary culture of the renal tubular epithelial cells was tried from a piece of percutaneous kidney biopsy specimen. Successive passages of the cells were possible until fourth passage. With these cells, morphologic characteristics of the cultured cells and integrin expression profiles were investigated. On light and electron microscopy, these cells were characterized by the cobblestone-like growth, presence of microvilli and tight junction, and the preservation of polarity. Immunohistochemical studies demonstrated the epithelial nature of these cells and particularly their differentiation from renal tubular epithelial cells, of either proximal or distal nephronic segment. The integrin profile confirms the epithelial nature of the cell. We hope that our results facilitate the understanding of pathophysiology of renal tubular cells from the patient directly.  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