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   12231篇
  免费   654篇
  国内免费   112篇
耳鼻咽喉   114篇
儿科学   269篇
妇产科学   118篇
基础医学   1270篇
口腔科学   185篇
临床医学   833篇
内科学   3387篇
皮肤病学   156篇
神经病学   681篇
特种医学   400篇
外科学   2373篇
综合类   67篇
预防医学   261篇
眼科学   163篇
药学   821篇
中国医学   21篇
肿瘤学   1878篇
  2023年   75篇
  2022年   160篇
  2021年   319篇
  2020年   201篇
  2019年   249篇
  2018年   294篇
  2017年   268篇
  2016年   297篇
  2015年   327篇
  2014年   388篇
  2013年   481篇
  2012年   781篇
  2011年   832篇
  2010年   477篇
  2009年   399篇
  2008年   657篇
  2007年   701篇
  2006年   727篇
  2005年   740篇
  2004年   706篇
  2003年   701篇
  2002年   705篇
  2001年   223篇
  2000年   214篇
  1999年   246篇
  1998年   144篇
  1997年   116篇
  1996年   113篇
  1995年   96篇
  1994年   98篇
  1993年   93篇
  1992年   117篇
  1991年   147篇
  1990年   116篇
  1989年   134篇
  1988年   117篇
  1987年   74篇
  1986年   68篇
  1985年   48篇
  1984年   46篇
  1983年   41篇
  1982年   23篇
  1980年   15篇
  1979年   36篇
  1978年   16篇
  1976年   12篇
  1973年   15篇
  1971年   21篇
  1969年   17篇
  1966年   15篇
排序方式: 共有10000条查询结果,搜索用时 140 毫秒
51.
Many asthmatic children have experienced atopic dermatitis in their younger days. As it is very difficult to cure childhood asthma we attempted to determine the anti-allergic drug effects in preventing the development of asthma by using ketotifen on atopic dermatitis patients. The study was designed as a placebo controlled double blind trial of 128 atopic dermatitis patients aged from 2-34 months. 91 patients were given complete analysis in the study, 33 patients were given only a safety rate and 4 patients were dropped. The 91 patients were followed for 52 weeks. Our primary finding was that the development of bronchial asthma was inhibited in the ketotifen group compared to the placebo controlled group with a statistically significant degree (p less than 0.001). We also found that clinical symptoms of atopic dermatitis were significantly improved in the ketotifen group (p less than 0.001). Only 5 patients complained of mild side effects.  相似文献   
52.
Eosinophilic bronchitis without asthma can cause a persistent non-productive cough which is resistant to bronchodilator therapy. To understand the mechanism of the cough in this disorder, an animal model of eosinophilic bronchitis was developed. Guinea-pigs were treated with transnasal administration of polymyxin B or saline twice a week for 3 weeks. The number of eosinophils in bronchoalveolar lavage fluid increased in polymyxin B-treated animals when compared with those treated with saline. In addition, histological examination showed that the number of eosinophils infiltrated into the tracheal epithelium increased; injury to the tracheal epithelium was greater in polymyxin B-treated animals. The numbers of coughs induced by saline and each concentration of capsaicin (10–18, 10–16, 10–14M) were greater in the polymyxin B-treated animals. FK-224 (a neurokinin receptor antagonist) decreased the heightened cough reflex in this animal model of eosinophilic bronchitis. These findings suggest that neuropeptides, and particularly neurokinins, are involved in the heightened cough receptor sensitivity in eosinophilic bronchitis without asthma. This has implications for better understanding of this disorder and its treatment.  相似文献   
53.
A 31-year-old adult with an aortico-left ventricular tunnel (ALVT) arising from the right aortic sinus is reported. Preoperative transesophageal echocardiography demonstrated a ruptured sinus of Valsalva with severe aortic valve regurgitation which originated from the right coronary sinus entering the outlet portion of the left ventricular outflow tract. Operation revealed the aortic entrance of the tunnel was above the right coronary sinus. Direct closure of the orifice of the tunnel using three stitches of 4-0 polypropylene with felt and aortic valve replacement (AVR) was performed. At 10-month follow-up the patient is asymptomatic and receiving no oral medications except anticoagulants. We believe this to be the oldest case of ALVT managed with AVR.  相似文献   
54.
Objective.To identify the clinicopathological and chemoresistant factors predicting the response to neoadjuvant chemotherapy and the patient prognosis in high-risk cervical carcinomas.Methods.We retrospectively reviewed 47 patients with locally advanced or bulky cervical carcinoma treated with two courses of intraarterial infusion of cisplatin, doxorubicin, mitomycin C, and 5-fluorouracil (5-FU), followed by radical hysterectomy at our hospital between 1988 and 1995. Expressions of the chemoresistance-related proteins, such as P-glycoprotein, glutathioneS-transferase π (GST-π), and proliferating cell nuclear antigen (PCNA) in the tumor cells, were examined by immunohistochemistry using pretreatment biopsy specimens. These results were compared with the chemotherapeutic response, which was evaluated by magnetic resonance imaging (MRI) and histopathology. Outcome of the patients was also studied.Results.Chemotherapeutic effect of either complete (CR) or partial (PR) response on MRI was obtained in 36 of the 47 (86%) patients. Poor response to chemotherapy was significantly correlated with P-glycoprotein expression (P< 0.005) and low PCNA labeling (P< 0.05), but not GST-π expression in the tumor cells. Independent prognostic factors for patient survival were parametrial involvement and lymph node metastasis. Neither the expression of GST-π nor PCNA was correlated with the patient survival.Conclusion.Assessment of the expression of P-glycoprotein and PCNA is potentially useful for the prediction of tumor response to neoadjuvant chemotherapy for cervical carcinomas.  相似文献   
55.
Effects of a protein-free diet on the rat stomach   总被引:1,自引:0,他引:1  
The effects of a protein-free diet containing a mixture of free amino acids on the stomach were studied using male Wistar strain rats. In the forestomach, thickening of mucosa and hyperkeratosis appeared and papillomas frequently developed, but they did not occur in the control rats fed a semipurified diet. Mucous neck cells increased and parietal cells and chief cells decreased in the fundus. Goblet cells occurred in the antral glands, and intestinal metaplastic glands developed in the late stage of the experiment. The number of deoxyribonucleic acid-synthesizing cells in the glandular stomach was significantly higher than that of the control. Moreover, in the antrum, somatostatin-producing cells increased in the early stage and gastrin-producing cells decreased in the late stage. These results suggest that dietary protein might play a crucial role in the differentiation of gastric epithelium and the development of intestinal metaplasia in the stomach.  相似文献   
56.
57.
58.
The distribution patterns of choline acetyltransferase (CAT), as a marker for cholinergic neurons, and Calbindin-D28k (CaBP) immunoreactivities in the forebrain basal ganglia of the Japanese monkeyMacaca fuscata were compared. Similar distribution patterns of CAT and CaBP immunoreactivities were found in the medial septal nucleus (MS) and the nucleus of the diagonal band of Broca (DBB). Double-labeling fluorescence immunocytochemistry revealed that most, but not all, cholinergic neurons were CaBP-immunoreactive in the MS and DBB. The results suggest that CaBP may play a role in the septohippocampal cholinergic neuron system of the monkey.  相似文献   
59.
Predictors of healthy aging in men with high life expectancies.   总被引:5,自引:0,他引:5       下载免费PDF全文
OBJECTIVE: The purpose of this study was to identify risk factors that consistently predict staying healthy in contrast to developing clinical illness and/or physical and mental impairments. METHODS: More than 8000 men of Japanese ancestry were followed for 28 years with repeat examinations and surveillance for deaths and incident clinical illness. Physical and cognitive functions were measured in 1993. Measures of healthy aging included surviving and remaining free of major chronic illnesses and physical and cognitive impairments. RESULTS: Of 6505 healthy men at baseline, 2524 (39%) died prior to the final exam. Of the 3263 available survivors, 41% remained free of major clinical illnesses, 40% remained free of both physical and cognitive impairment, and 19% remained free of both illness and impairment. The most consistent predictors of healthy aging were low blood pressure, low serum glucose, not smoking cigarettes, and not being obese. CONCLUSIONS: Beyond the biological effects of aging, much of the illness and disability in the elderly is related to risk factors present at midlife.  相似文献   
60.
We investigated the relative effects of 0.5, 1.0, 1.5, 2.0 MAC halothane and enflurane, and concurrent noxious stimulus on hepatic blood flow and oxygen consumption in 14 mongrel dogs randomly divided into groups of seven each. Hepatic arterial and portal venous blood flow (HABF and PVBF, respectively) were measured continuously using ultrasonic transit time flow meter. Mean arterial blood pressure (MAP), cardiac index (CI), hepatic oxygen supply, and hepatic oxygen consumption (H O 2) were measured. Halothane significantly deceased HABF, but not PVBF in a dose dependent manner. Enflurane did not affect HABF and PVBF significantly. MAP and CI decreased in both groups, with halothane producing more marked decreases than enflurane. H O 2 did not change with enflurane, but did with halothane, producing significant differences, with halothane being greater at 1.5, 2.0 MAC. A noxious stimulus only caused minor change in blood flow. The results suggest that liver blood flow and oxygen consumption are affected differently by halothane and enflurane and that halothane has a stronger tendency to cause an imbalance between liver oxygen supply and consumption than dose enflurane.(Masaki E, Yasuda N, Tanifuji Y et al.: Effect of halothane and enflurane on hepatic blood flow and oxygen consumption in dogs. J Anesth 3: 118–122, 1989)  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