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   6575篇
  免费   337篇
  国内免费   44篇
耳鼻咽喉   147篇
儿科学   122篇
妇产科学   91篇
基础医学   760篇
口腔科学   272篇
临床医学   383篇
内科学   1662篇
皮肤病学   199篇
神经病学   673篇
特种医学   162篇
外科学   869篇
综合类   43篇
一般理论   1篇
预防医学   179篇
眼科学   55篇
药学   506篇
中国医学   17篇
肿瘤学   815篇
  2022年   59篇
  2021年   94篇
  2020年   57篇
  2019年   71篇
  2018年   111篇
  2017年   86篇
  2016年   96篇
  2015年   95篇
  2014年   126篇
  2013年   170篇
  2012年   243篇
  2011年   244篇
  2010年   154篇
  2009年   119篇
  2008年   257篇
  2007年   306篇
  2006年   309篇
  2005年   348篇
  2004年   299篇
  2003年   304篇
  2002年   280篇
  2001年   287篇
  2000年   252篇
  1999年   231篇
  1998年   106篇
  1997年   67篇
  1996年   67篇
  1995年   69篇
  1994年   61篇
  1993年   57篇
  1992年   180篇
  1991年   150篇
  1990年   173篇
  1989年   140篇
  1988年   137篇
  1987年   154篇
  1986年   119篇
  1985年   134篇
  1984年   94篇
  1983年   74篇
  1982年   36篇
  1980年   37篇
  1979年   63篇
  1978年   35篇
  1977年   35篇
  1975年   32篇
  1974年   39篇
  1973年   28篇
  1972年   33篇
  1971年   30篇
排序方式: 共有6956条查询结果,搜索用时 15 毫秒
31.
We herein report the case of a 53-year-old man with a nonspecific acute colonic ulcer whose liver function deteriorated after he had undergone hepatectomy. He was referred to our hospital for a hepatoma caused by hepatitis B virus and a right hemihepatectomy was performed. His liver function was poor after the operation, and minor complications such as pleural effusion and biliary fistula developed. A large amount of melena was seen 29 days after the hepatectomy and he developed hemorrhagic shock. Superior mesenteric arteriography revealed pooling of blood in both the hepatic flexure of the ascending colon and the cecum. An emergency right hemicolectomy was performed. There was a 5 x 1-mm ulcer 18 cm distal to the ileocecal valve. Numerous erosions were observed to be scattered throughout the colonic mucosa. The patient recovered slowly and was discharged 6 months after the hepatectomy. This is the first report of an acute colonic ulcer that could have been caused by liver dysfunction.  相似文献   
32.
Early gastric cancer manifested as brain metastasis: Report of a case   总被引:1,自引:0,他引:1  
A case of early gastric cancer, limited to submucosal layer, which was manifested as cerebral metastasis is presented herein. A 47-year-old man was admitted to Nagaoka Chuo General Hospital with convulsions and a disturbance in consciousness, where a computed tomography (CT) scan revealed a cerebral tumor in the left temporal lobe. The resected tumor was identified as a metastatic adenocarcinoma. Further investigation revealed gastric cancer involving the posterior wall of the cardia. At laparotomy, multiple and small metastases of the liver and a jejunal metastasis were found, and a palliative total gastrectomy was performed. The surgical specimen revealed a protruding, poorly differentiated medullary adenocarcinoma, with invasion of the submucosal layer. The patient died 4 months after undergoing the laparotomy. This case report is presented to make clinicians aware of the possibility that early gastric cancers may present as brain metastasis.  相似文献   
33.
Cutaneous tumour-like growths were observed on the face and other areas of the body surface of young Chilean flamingos. In the cells of these lesions, avian pox-specific cytoplasmic inclusion bodies were observed by light microscopy and virus particles were detected under an electron-microscope. It was diagnosed as avian pox.  相似文献   
34.
Extracellular single-unit activity was recorded from 21 median preoptic nucleus (MnPO) neurones, antidromically identified as projecting to the hypothalamic paraventricular nucleus (PVN), in urethane-anaesthetized male rats. Of these identified MnPO neurones, 14 displayed an excitatory response in neuronal excitability following electrical stimulation (5 Hz, 600 microA) of the A1 noradrenergic region of the ventrolateral medulla, while the remaining neurones were unresponsive. The excitatory response of MnPO neurones was blocked by microiontophoretically applied phentolamine, an alpha-adrenoceptor antagonist, but not by timolol, a beta-adrenoceptor antagonist. These results suggest that the A1 region acts to enhance the activity of MnPO neurones projecting to the PVN via an alpha-adrenoceptor mechanism.  相似文献   
35.
Clinical features such as types of diseases, sex ratio, age of onset, sites of initial involvement, the appearance of bulbar signs, and duration of illness were studied in 52 patients with motor neuron disease (MND) with a special reference to immunoglobulin in cerebrospinal fluid (CSF) and serum. Although MND has been thought to be a degenerative disease of unknown cause, our data suggested there are some immunological abnormalities in this disease. The duration of illness and the abnormalities of CSF immunoglobulins appeared to be correlated with the type of disease and the site of initial involvement. However, whether or not these abnormalities in CSF immunoglobulins are directly related to the pathogenesis of MND remains unclear.  相似文献   
36.
Optimal initial palliation and a subsequent staged approach is mandatory for high-risk Fontan candidates. We describe the case of mitral atresia with severe tricuspid regurgitation and pulmonary hypertension successfully managed by repeated palliation from the neonatal period and 2-stage Fontan surgery. A 1-month-old boy diagnosed with mitral atresia and double-outlet right ventricle underwent pulmonary artery banding at 1 month of age, followed by repeated pulmonary artery banding accompanied by tricuspid annuloplasty and atrial septal defect enlargement at 6 months. Because of the presence of pulmonary artery distortion, right ventricular dysfunction, and borderline pulmonary vascular resistance, a hemi-Fontan procedure was conducted with extended pulmonary artery plasty when the boy was 3 years and 8 months old. Cardiac catheterization done 3 months after showed improvement in risk factors, and the final Fontan operation (total cavopulmonary connection) was successfully done in conjunction with repeated tricuspid annuloplasty when the boy was 4 years and 5 months old. The patient remains in excellent clinical condition at the last follow-up 5 years after the final Fontan procedure with sinus rhythm and good ventricular function.  相似文献   
37.
38.
In order to determine the prevalence of allergic disorders and their association with agricultural factors, a total of 3,717 inhabitants of rural districts in Kumamoto Prefecture were ashed to fill out a questionnaire concerning their allergic status. The results obtained were as follows: One or more items of allergic symptoms were reported by 44% of the subjects. The prevalence rate of each symptom was 8% for respiratory organs, 5% for delayed type of respiratory disorders, 10% for nasal mucosa, 16% for eyes, 16% for urticaria-like derma and 26% for eczema-like derma. Twenty-one percent of the subjects had past histories of allergic diseases such as asthma (3%), nasal allergy (3%), urticaria (6%), contact dermatitis (9%) and so forth. These allergic conditions were seen to be more common among farmers than non-agricultural workers, and also among subjects with allergic constitution than those without such constitution. The highest (62%) prevalence of allergic symptoms was observed in farmers engaged in poultry raising, followed by those engaged in raising flowers (58%), tobacco (58%), cortinellus shiitake (55%), cucumber in plastic greenhouse (53%) and mandarin orange (53%). Among the symptomatic subjects, 12-38% of those with each symptom gave farm work as the direct causative factor for developing the corresponding symptom. Pesticide spraying was the most common agent among those factors.  相似文献   
39.
The in vitro clonogenic assay has been used to assess the biological effects of estradiol-17 beta (E 2) and an antiestrogen, tamoxifen (TAM) on human breast cancer, and the results were compared with the estrogen receptor status (ER). The sera used were treated with dextran-coated charcoal to avoid the modification effects of the endogenous hormones. There was a significant difference between ER (+) and ER (-) breast cancers in the incidence of cases in which the plating efficiency of cancers increased more than 50% over those of untreated control by adding 10(-8) M of E 2 (40.2% vs. 21.3%). TAM, 10(-6) M revealed a less than 50% colony formation of the control in 30.5% of ER (+) cancers, whereas only 13.0% of ER (-) cancers showed a response to TAM.  相似文献   
40.
Glutathione transferase P (GST-P; glutathione transferase, EC 2.5.1.18) is known to be specifically expressed at high levels in precancerous lesions and in hepatocellular carcinomas from a very early phase of chemically induced hepatocarcinogenesis in the rat. The almost invariable occurrence of this phenotype in these lesions strongly suggests a mechanism by which GST-P gene is activated together with a crucial transforming gene of liver cells. To distinguish the two alternative possibilities--either the GST-P gene is coactivated with a closely located transforming gene by a cis mechanism or it is activated in trans by a common trans-acting factor--we carried out carcinogenesis experiments using transgenic rats harboring the bacterial chloramphenicol acetyltransferase reporter gene ligated to the upstream regulatory sequence of the GST-P gene. In each of three independent lines tested, liver foci and nodules produced by chemical carcinogens (Solt-Farber procedure) were found to express high levels of chloramphenicol acetyltransferase activity, indicating clearly that the GST-P gene is activated by a trans mechanism during hepatocarcinogenesis.  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