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   9957篇
  免费   1053篇
  国内免费   26篇
耳鼻咽喉   103篇
儿科学   295篇
妇产科学   252篇
基础医学   1388篇
口腔科学   300篇
临床医学   1258篇
内科学   1968篇
皮肤病学   101篇
神经病学   914篇
特种医学   339篇
外国民族医学   3篇
外科学   1260篇
综合类   199篇
一般理论   10篇
预防医学   1156篇
眼科学   106篇
药学   732篇
中国医学   3篇
肿瘤学   649篇
  2022年   68篇
  2021年   118篇
  2020年   96篇
  2019年   144篇
  2018年   158篇
  2017年   121篇
  2016年   114篇
  2015年   164篇
  2014年   241篇
  2013年   300篇
  2012年   477篇
  2011年   528篇
  2010年   268篇
  2009年   292篇
  2008年   427篇
  2007年   445篇
  2006年   452篇
  2005年   443篇
  2004年   398篇
  2003年   382篇
  2002年   362篇
  2001年   357篇
  2000年   333篇
  1999年   272篇
  1998年   123篇
  1997年   119篇
  1996年   105篇
  1995年   122篇
  1994年   104篇
  1993年   95篇
  1992年   214篇
  1991年   219篇
  1990年   219篇
  1989年   194篇
  1988年   181篇
  1987年   180篇
  1986年   202篇
  1985年   191篇
  1984年   138篇
  1983年   127篇
  1982年   81篇
  1981年   83篇
  1979年   138篇
  1978年   117篇
  1977年   95篇
  1976年   87篇
  1975年   71篇
  1974年   87篇
  1973年   93篇
  1972年   78篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
In this report, we give details of two families in which fixed subaortic stenosis was found in more than one member. It is rare for this entity to show familial incidence.  相似文献   
42.
Magnetic resonance (MR) imaging may be a noninvasive method for assessing perfusion of vascularized bone grafts placed for treatment of avascular necrosis. One proximal femur of seven beagles was devascularized, with insertion of a vascularized fibular graft. MR imaging at 1 week (seven dogs) and 6 weeks (five dogs) after surgery included pre- and postcontrast spin-echo sequences, unenhanced twodimensional time-of-flight (TOF) vascular imaging, and dynamic gradient-echo imaging during infusion of gadolinium. Relative signal intensity values of selected regions obtained from the dynamic gradientecho images were plotted as percent enhancement versus time. In the operated hip, MR imaging did not show enhancement in six of seven femoral heads and greater trochanters at 1 week after surgery, with similar results after 6 weeks. MR imaging of fibular grafts 6 weeks after surgery showed an initial rapid increase in enhancement and a subsequent slower increase in five of five dogs, although no enhancement was seen in six of seven dogs at 1 week. These findings contrasted with a rapid initial increase in enhancement followed by slow decline in non-operated hips. Two-dimensional TOP imaging did not show the vascular pedicle of the graft in any dog. Findings of radionuclide bone scanning performed 1 week after surgery were consistent with devascularization of the operated femur and fibular graft. However, tetracycline distribution and histologic findings confirmed the viability of five of five grafts within the devascularized femurs 6 weeks after surgery. Thus, dynamic contrast-enhanced MR imaging at 6 weeks after surgery is valuable for assessing vascular bone graft perfusion, while similar imaging at 1 week may suggest otherwise.  相似文献   
43.
44.
A multicancer site, multifactor case-control study was undertaken to generate hypotheses about possible occupational carcinogens. Probing interviews were carried out with eligible cases, comprising all incident cases of 20 types of cancer who were male, aged 35-70 years, and a resident in Montreal. The interview was designed to obtain detailed lifetime job histories and information on potential confounders. Each job history was reviewed by a team of chemists and industrial hygienists who translated it into a history of occupational exposures. These occupational exposures were then analyzed as potential risk factors in relation to the sites of cancer included; 3,726 cases were interviewed. For each site of cancer analyzed, controls were selected from among the other sites in the study. This report concerns the associations between the 12 main types of cancer in our series and 10 inorganic dusts that are found mainly in construction and metal industries. All site-exposure combinations were investigated. After intensive control for confounding, nonadenocarcinoma (NAC) of the lung was associated with long duration-high level exposure to silica (odds ratio [OR] = 1.4), excavation dust (OR = 1.9), concrete dust (OR = 2.5), abrasives dust (OR = 1.4), and alumina (OR = 1.5). It was difficult to disentangle the relative effects of those substances, and confounding among them was a distinct possibility. Although residual confounding by some uncontrolled factors may explain the elevated ORs, the results were compatible with the hypothesis of a nonspecific relation between NAC of the lung and respirable inorganic dusts as a class. Other associations that remained suggestive after in-depth analysis were silica and stomach cancer (OR = 1.2) and concrete dust and lymphoma (OR = 2.9).  相似文献   
45.
A single case of bilateral congenital mydriasis is described. A review of the literature is presented and possible modes of inheritance are discussed.  相似文献   
46.
Frantz's tumour (papillary and cystic tumour) of the pancreas is a rare neoplasm usually seen in young women. It is of low grade malignancy and deserves special note among pancreatic malignancies as it is frequently amenable to local resection and has a good long-term survival rate after excision. Three such cases have been treated at Westmead Hospital, one young male and two females. In two the disease was confined to the pancreas. In one, local invasion outside the pancreas and trans-coelomic spread to the ovaries was present at the time of diagnosis. Complete surgical removal of macroscopic disease was achieved in all three and all remain disease free between 2 and 4 years post-surgery. All have good exocrine and endocrine pancreatic function. These cases are discussed in detail. The need to be aware of this uncommon variant of pancreatic cancer is stressed. Investigation and treatment options are reviewed. The role of cytology studies in diagnosis and the potential for long-term surgical control of this tumour are highlighted on the basis of our limited experience and that presented in recent surgical literature.  相似文献   
47.
The clinical presentation of SARS is nonspecific and diagnostic tests do not provide accurate results early in the disease course. Initial diagnosis remains reliant on clinical assessment. To identify features of the clinical assessment that are useful in SARS diagnosis, the exposure status and the prevalence and timing of symptoms, signs, laboratory and radiographic findings were determined for all adult patients admitted with suspected SARS during the Toronto SARS outbreak. Findings were compared between patients with laboratory-confirmed SARS and those in whom SARS was excluded by laboratory or public health investigation. Of 364 cases, 273 (75%) had confirmed SARS, 30 (8%) were excluded, and 61 (17%) remained indeterminate. Among confirmed cases, exposure occurred in the healthcare environment (80%) or in the households of affected patients (17%); community or travel-related cases were rare (<3%). Fever occurred in 97% of patients by the time of admission. Respiratory findings including cough, dyspnea and pulmonary infiltrates evolved later and were present in only 59, 37 and 68% of patients, respectively, at admission. Direct exposure, fever on the first day of illness, and elevated temperature, pulmonary infiltrates, lymphopenia and thrombocytopenia at admission were associated with confirmed cases. Rhinorrhea, sore throat, and an elevated neutrophil count at admission were associated with excluded cases. In the absence of fever or significant exposure, SARS is unlikely. Other clinical, laboratory and radiographic findings further raise or lower the likelihood of SARS and provide a rational basis for estimating the likelihood of SARS and directing initial management.  相似文献   
48.
Phase I trial of piroxicam in 62 dogs bearing naturally occurring tumors   总被引:3,自引:0,他引:3  
Summary Piroxicam, a nonsteroidal antiinflammatory drug, was given to 62 dogs bearing naturally occurring tumors in a phase I clinical trial. Dose escalation was performed, with oral doses ranging from 0.5 mg/kg every 48 h (q48h) to 1.5 mg/kg q48h being tested. Dose-limiting gastromestinal irritation/ulceration occurred in all four animals that received 1.5 mg/kg q48h. The maximum tolerated dose was 1 mg/kg q48h. Subclinical renal papillary necrosis occurred in two dogs (initial dosages, 1 and 1.5 mg/kg q48h, respectively). Following dose escalation, an additional group of dogs was treated with 0.3 mg/kg piroxicam q24h per os, the accepted canine dosage prior to this trial. Inclusion of this treatment group enabled evaluation of the toxicity of and tumor response to a daily dosage regimen. No complete remissions occurred in this trial. Partial remission was documented in three of ten dogs exhibiting transitional-cell carcinoma, in three of five animals bearing squamous-cell carcinoma, in one of three dogs displaying mammary adenocarcinoma, and in the one dog that exhibited a transmissible venereal tumor. The results of this study support the additional evaluation of piroxicam in a phase II clinical trial in dogs bearing naturally occurring tumors.This investigation was supported by Pfizer Inc.  相似文献   
49.
OBJECTIVE: To determine to what degree attending physicians contribute to cost variations in the care of ventilator-dependent newborns. DATA SOURCES: Clinical data were merged with hospital financial data describing daily ancillary care costs during the first two weeks of life for 132 extremely low-birthweight newborns. In addition, each patient's chart was reviewed and illness severity graded using both SNAP and CRIB scores. STUDY DESIGN: This was a retrospective cohort of infants with birth weights of less than 1,001 grams and respiratory distress syndrome requiring mechanical ventilation in the first day of life. From birth up to two weeks of life, each received care directed by only one of 11 faculty neonatologists in a single university hospital. Data were analyzed stratified by these physicians. t-Test, ANOVA, and chi-square were used to assess bivariate data. For continuous data, log linear regressions were used. PRINCIPAL FINDINGS: After controlling for illness severity, when stratified by physicians, there were significant variances in the costs of ancillary resources for the study infants (p < .0001). Twenty-nine percent of the variance was attributable to whether or not the hospital day included the use of a ventilator. Physician identity explained only 5.6 percent (p < .0001). CONCLUSIONS: Physician identity was significant but explained less than 6 percent of the total variance in ancillary costs. Whether or not a ventilator was used during care was far more important. We conclude that for very sick babies during the first two weeks of care, reducing variations in ancillary services utilization among neonatologists will yield only modest savings.  相似文献   
50.
Diarrhea has been reported as an early, mild, and uncommon complication of carbamazepine (CBZ) therapy. We report three cases of intractable diarrhea induced by CBZ necessitating discontinuation of the drug.  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