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   76628篇
  免费   5688篇
  国内免费   841篇
耳鼻咽喉   958篇
儿科学   1857篇
妇产科学   1704篇
基础医学   12086篇
口腔科学   1905篇
临床医学   7655篇
内科学   14614篇
皮肤病学   1277篇
神经病学   6726篇
特种医学   3303篇
外国民族医学   50篇
外科学   9912篇
综合类   2289篇
现状与发展   1篇
一般理论   87篇
预防医学   5799篇
眼科学   1453篇
药学   5845篇
  3篇
中国医学   864篇
肿瘤学   4769篇
  2023年   364篇
  2022年   873篇
  2021年   1597篇
  2020年   1071篇
  2019年   1372篇
  2018年   1562篇
  2017年   1182篇
  2016年   1311篇
  2015年   1678篇
  2014年   2118篇
  2013年   3021篇
  2012年   3975篇
  2011年   4133篇
  2010年   2909篇
  2009年   2376篇
  2008年   3475篇
  2007年   3586篇
  2006年   3572篇
  2005年   3402篇
  2004年   3265篇
  2003年   3109篇
  2002年   3103篇
  2001年   2525篇
  2000年   2504篇
  1999年   2224篇
  1998年   1042篇
  1997年   860篇
  1996年   763篇
  1995年   775篇
  1994年   642篇
  1993年   663篇
  1992年   1528篇
  1991年   1467篇
  1990年   1392篇
  1989年   1386篇
  1988年   1148篇
  1987年   1161篇
  1986年   1089篇
  1985年   988篇
  1984年   718篇
  1983年   663篇
  1982年   468篇
  1981年   453篇
  1980年   386篇
  1979年   635篇
  1978年   381篇
  1977年   369篇
  1975年   381篇
  1974年   418篇
  1973年   354篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
81.
Temporoparietal and posterior cingulate metabolism deficits characterize patients with Alzheimer's disease (AD). A H(2)(15)O resting PET scan covariance pattern, derived by using multivariate techniques, was previously shown to discriminate 17 mild AD patients from 16 healthy controls. This AD covariance pattern revealed hypoperfusion in bilateral inferior parietal lobule and cingulate; and left middle frontal, inferior frontal, precentral, and supramarginal gyri. The AD pattern also revealed hyperperfusion in bilateral insula, lingual gyri, and cuneus; left fusiform and superior occipital gyri; and right parahippocampal gyrus and pulvinar. In an independent sample of 23 outpatients with mild cognitive impairment (MCI) followed at 6-month intervals, the AD pattern score was evaluated as a predictor of cognitive decline. In this MCI sample, an H2(15)O resting PET scan was carried out at baseline. Mean duration of follow-up was 48.8 (SD 15.5) months, during which time six of 23 MCI patients converted to AD. In generalized estimating equations (GEE) analyses, controlling for age, sex, education, and baseline neuropsychological scores, increased AD pattern score was associated with greater decline in each neuropsychological test score over time (Mini Mental State Exam, Selective Reminding Test delayed recall, Animal Naming, WAIS-R digit symbol; Ps<0.01-0.001). In summary, a resting PET covariance pattern previously reported to discriminate AD patients from control subjects was applied prospectively to an independent sample of MCI patients and found to predict cognitive decline. Independent replication in larger samples is needed before clinical application can be considered.  相似文献   
82.
The case reports of 102 patients with subdural empyema, diagnosed in the years 1935-83, were reviewed to determine the factors affecting the outcome. Statistical analysis (likelihood ratio tests with chi square approximation and logistic regression) showed that year of diagnosis (p less than 0.01) and level of consciousness at the moment of diagnosis (p less than 0.01) had a significant bearing on the chance to survive and that these same two factors (each factor p less than 0.01) and extent of subdural pus accumulation at the moment of diagnosis (p less than 0.05) had a significant bearing on the chance of survival without severe disability. Among others the duration of the disease up to the moment of diagnosis and the mode of the first surgical procedure had no significant bearing on the outcome. These results together with those in the literature are discussed and it is concluded that diagnosis and treatment before the patient lapses into stupor or coma, increases the chance of survival and that with adequate management a mortality rate of 10% or lower is to be expected.  相似文献   
83.
84.
In France, general practitioners (GPs) express difficulties in exercise of home palliative care. Those difficulties are described in various studies but none assesses the multidisciplinary collaboration’s impact. In the present study (2005–2008), 291 GPs included in a palliative care network responded to a questionnaire. Results showed the benefits of this partnership organization. Detailed analysis of 36 collaboration cases clarified the reasons for these difficulties and the network influence.  相似文献   
85.
86.
The alpha-chloroether carcinogen chloromethylmethyl ether (CME) and its impurity bis(chloromethyl)ether (BCME) are direct-acting alkylating agents. Vinyl chloride (VC) is an indirect-acting carcinogen but its accepted carcinogenic intermediate, chloroethylene oxide, is also an alpha-chloroether. Both CME-BCME and VC have been in industrial use since about 1950. Hence, they were selected for comparison of potency as human carcinogens using numerous epidemiologic reports. There were 115 deaths due to angiosarcoma of the liver among several hundred thousand VC-exposed workers on the basis of reports from 10 countries during 1955 and 1984. Reports from five countries cited a total of 87 respiratory cancer deaths among only 3024 CME-BCME-exposed workers. If a recent court settlement in the United States is taken into account, the number of respiratory cancer deaths due to CME-BCME rises to 117. On the basis of these numbers of cancer deaths, and the levels and durations of exposure, it is concluded that VC is a weak human carcinogen compared to CME-BCME.  相似文献   
87.
Double-outlet right ventricle and severe systemic outflow tract hypoplasia comprises a subset of patients in whom total correction or palliation requires complex surgical procedures in the neonatal period. Our experience with 3 patients illustrates the difficulties associated with treatment and suggests possible surgical options for this otherwise lethal variant of the Taussig-Bing syndrome.  相似文献   
88.
Patients with complaints of halitosis do seek treatment from physicians and dental practitioners, because of the fear that their halitosis may interfere with their social activities. Although the prevalence of halitosis has been reported to be as high as 50%, most physicians and dental practitioners are poorly informed about the causes and treatments of halitosis. In order to care for patients with complaints of halitosis a multidisciplinary team was established at the Erasmus Medical Centre, Rotterdam, The Netherlands. The team included a dental hygienist, an otorhinolaryngologist, and a dentist, who developed a special halitosis programme. One short press release regarding the establishment of the team, was provided to the national press-centre. In the out-patient clinic more than 700 patients were seen by the team. Using a structured questionnaire fed to a PC, patients answered questions regarding complaints about the oral cavity, the upper respiratory tract, the throat, their general health, their cleansing habits of the oral cavity, and prior experiences with general physicians, dental practitioners, and medical specialists. They underwent examinations of the extent of their halitosis, of the perioral and neck region, the oral cavity, the upper respiratory tract, and the upper digestive tract. Finally, the members of the team came to a joint diagnosis and a joint treatment plan for every individual patient. Of the first 700 consecutive patients around 90% had a natural dentition without removable partial dentures. More than 60% were diagnosed as having periodontal disease with pockets of 4 mm or more in the maxilla. This figure was more than 50% in the mandible. Around 95% had tongue coating.  相似文献   
89.
Kollicoat IR, a new pharmaceutical excipient developed as a coating polymer for instant release tablets, was evaluated as a carrier in solid dispersions of Itraconazole. The solid dispersions were prepared by hot stage extrusion. Modulated temperature differential scanning calorimetry and X-ray powder diffraction were used to evaluate the miscibility of the drug and the carrier. The pharmaceutical performance was evaluated by dissolution experiments, performed in simulated gastric fluid without pepsin (SGF(sp)). In the X-ray diffractograms no Itraconazole peaks were visible; the polymer on the other hand appeared to be semi-crystalline. Moreover, its crystallinity increased during the extrusion process due to exposure to heat and shear forces. Modulated temperature differential scanning calorimetry analysis showed that the drug and the polymer formed a two phase system. Separate clusters of glassy Itraconazole were present for drug loads of 40% or higher, indicating further phase separation. Dissolution measurements demonstrated a significantly increased dissolution rate for the solid dispersions compared to physical mixtures. Interestingly the physical mixture made up of glassy Itraconazole and Kollicoat IR (20/80, w/w) showed a dissolution rate and maximum that was much higher than that of the physical mixture made up of crystalline Itraconazole and that of pure glassy Itraconazole. The results of this study show that Kollicoat IR is a promising excipient for the formulation of solid dispersions of Itraconazole prepared by hot stage extrusion.  相似文献   
90.
The authors present an update version of the indications for radiotherapy in the management of benign diseases. This is based on available randomized trials and recent international meetings. Validated indications remain the prevention of resected heterotopic bone ossifications, kelo?ds scars and pterygium and also treatment of arteriovenous malformations; the place of radiotherapy for malignant exophtalmia is more and more restricted. Randomized trials have demonstrated the efficacy of endobrachytherapy in the prevention of restenosis after angioplasty but the use of embedded stent has replaced this indication. Macular degeneration is no more an indication of radiotherapy. Quality requirements for radiotherapy are identical for benign or malignant indications.  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