全文获取类型
收费全文 | 823篇 |
免费 | 50篇 |
国内免费 | 45篇 |
专业分类
耳鼻咽喉 | 1篇 |
儿科学 | 41篇 |
妇产科学 | 8篇 |
基础医学 | 58篇 |
口腔科学 | 13篇 |
临床医学 | 140篇 |
内科学 | 236篇 |
皮肤病学 | 8篇 |
神经病学 | 28篇 |
特种医学 | 129篇 |
外科学 | 72篇 |
综合类 | 22篇 |
预防医学 | 81篇 |
眼科学 | 6篇 |
药学 | 54篇 |
中国医学 | 1篇 |
肿瘤学 | 20篇 |
出版年
2021年 | 4篇 |
2018年 | 7篇 |
2016年 | 7篇 |
2015年 | 7篇 |
2014年 | 12篇 |
2013年 | 32篇 |
2012年 | 18篇 |
2011年 | 22篇 |
2010年 | 35篇 |
2009年 | 39篇 |
2008年 | 33篇 |
2007年 | 70篇 |
2006年 | 31篇 |
2005年 | 34篇 |
2004年 | 28篇 |
2003年 | 26篇 |
2002年 | 14篇 |
2001年 | 14篇 |
2000年 | 15篇 |
1999年 | 12篇 |
1998年 | 43篇 |
1997年 | 33篇 |
1996年 | 38篇 |
1995年 | 25篇 |
1994年 | 17篇 |
1993年 | 22篇 |
1992年 | 13篇 |
1991年 | 9篇 |
1990年 | 15篇 |
1989年 | 31篇 |
1988年 | 35篇 |
1987年 | 23篇 |
1986年 | 25篇 |
1985年 | 16篇 |
1984年 | 9篇 |
1983年 | 10篇 |
1982年 | 11篇 |
1981年 | 6篇 |
1980年 | 7篇 |
1979年 | 4篇 |
1978年 | 9篇 |
1977年 | 12篇 |
1976年 | 5篇 |
1975年 | 7篇 |
1972年 | 2篇 |
1971年 | 2篇 |
1966年 | 3篇 |
1946年 | 2篇 |
1940年 | 2篇 |
1916年 | 2篇 |
排序方式: 共有918条查询结果,搜索用时 15 毫秒
91.
92.
Cardiac abnormalities such as mitral valve prolapse (MVP) are reported to
be common features of the Ehlers Danlos syndrome (EDS), and it has been
suggested that the majority of patients with type IV EDS will have cardiac
involvement and vascular aneurysms. However, the evidence for valve lesions
is inconsistent and often based on early clinical studies using mainly
M-mode echo. We studied 33 patients (six male, 27 female; median age 35 yr)
with EDS (30 type I, II or III, three type IV) and 30 age- and sex-matched
controls. The study assessed skin stretch and joint hypermobility using
Beighton and Contompasis scores. Echocardiographic examination included
standard two-dimensional views from the parasternal and apical windows, and
measurement of the aorta at four sites (annulus, sinotubular junction, arch
and abdominal aorta). Echocardiographic abnormalities were found in four
patients (12.1%) (one atrial septal aneurysm, one tricuspid prolapse, two
MVP) and two controls (6.7%). MVP was found in 6.1% of EDS patients and 7%
of controls. Seven patients had previously been diagnosed as having MVP;
only two were shown to have true MVP using current criteria. None of those
with type IV EDS had any echocardiographic abnormality. No patients with
EDS had mean aortic dimensions outside the normal range at any of the
points tested. Cardiac symptoms were more frequent amongst the patients
than controls (atypical chest pain 48%, P = 0.0001; palpitation 39%, P =
0.001; exertional dyspnoea 30%). A wide range of rheumatological complaints
were reported (current arthralgia 75%; recent back pain 72%, P = 0.005;
recurrent dislocation 72%). Contrary to earlier published observations, we
have not found an increased incidence of cardiac abnormalities in EDS. This
syndrome may be relatively more benign, from the cardiac point of view,
than was previously thought.
相似文献
93.
Stijn JB Van Weyenberg Sietze T Van Turenhout Maarten AJM Jacobs Gerd Bouma Chris JJ Mulder 《Digestive endoscopy》2012,24(4):247-254
Background and Aim: Little is known about the causes of overt obscure gastrointestinal bleeding (OGIB) in patients using anti‐thrombotic therapy. We aimed to describe video capsule endoscopy (VCE) findings and to identify factors associated with positive findings in these patients. Methods: We carried out a retrospective study of 56 patients who underwent VCE for evaluation of previous overt OGIB during anti‐thrombotic therapy. VCE studies were re‐evaluated by a gastroenterologist blinded to clinical details. Clinical data included in the multivariate analysis were sex, age, indication for and type of anti‐thrombotic therapy, hemodynamic instability on admission, type of blood loss, hemoglobin on admission, use of a proton pump inhibitor, NSAID use, time between bleeding episodes and VCE, and whether or not anti‐thrombotic therapy was resumed before the VCE study. Results: A probable cause for gastrointestinal bleeding was identified in 28 (50%) of the 56 studies. Angiodysplasia was found in 19 patients. Twenty‐two studies showed a possible cause in the small bowel. Multivariate logistic regression analysis showed that reinstitution of anti‐thrombotic therapy before VCE was carried out was the only independent predictor of positive VCE findings (OR: 8.61, 95% CI: 1.20–60.42, P = 0.032). Conclusions: Small intestinal angiodysplasia was the most common cause for overt OGIB. Reinstitution of withdrawn anti‐thrombotic drugs before the VCE examination was carried out was associated with positive VCE findings in multivariate analysis. 相似文献
94.
JB Gubbay A Al-Rezqi M Hawkes L Williams SE Richardson A Matlow 《The Canadian Journal of Infectious Diseases & Medical Microbiology》2012,23(2):78-81
OBJECTIVE:
To describe the viral etiology and epidemiology of nosocomial viral gastroenteritis (NVG) at a tertiary care pediatric hospital and identify any changes over the past two decades.METHODS:
Retrospective review of all patients with laboratory-confirmed NVG at The Hospital for Sick Children (Toronto, Ontario), from January 1, 2004, to December 31, 2005.RESULTS:
One hundred forty-two episodes of NVG were found among 133 patients, occurring in 0.48 of 100 admissions. The median age was two years; 42% were <1 year of age and 41% were immunocompromised. The most commonly detected pathogen was torovirus (67% of episodes), followed by rotavirus (19%) and adenovirus (9%). Seventy-five cases (53%) were epidemiologically linked in 32 separate clusters (median cluster size two, range two to four). The NVG rate fell from 0.63 of 100 to 0.22 of 100 admissions after March 2005 (P<0.001) when enhanced infection control precautions were instituted in response to an outbreak of vancomycin-resistant Enterococcus.CONCLUSIONS:
Torovirus remains the most commonly identified cause of NVG at The Hospital for Sick Children. Most NVG cases were epidemiologically linked, and a significant reduction in cases occurred after the institution of enhanced infection control practices following an outbreak of vancomycin-resistant Enterococcus. Improved education and surveillance for NVG should lead to further reduction in this problem. 相似文献95.
Sridharan Raghavan Mark C. Pachucki Yuchiao Chang Bianca Porneala Caroline S. Fox Josée Dupuis James B. Meigs 《Journal of general internal medicine》2016,31(10):1127-1133
BACKGROUND
Obesity and diabetes family history are the two strongest risk factors for type 2 diabetes (T2D). Prior work shows that an individual’s obesity risk is associated with obesity in social contacts, but whether T2D risk follows similar patterns is unknown.OBJECTIVE
We aimed to estimate the relationship between obesity or diabetes in an individual’s social contacts and his/her T2D risk. We hypothesized that obesity and diabetes in social contacts would increase an individual’s T2D risk.DESIGN
This was a retrospective analysis of the community-based Framingham Offspring Study (FOS).PARTICIPANTS
FOS participants with T2D status, height and weight, and at least one social contact were eligible for this study (n?=?4797 at Exam 1). Participants’ interpersonal ties, cardiometabolic and demographic variables were available at eight exams from 1971 to 2008, and a T2D additive polygenic risk score was measured at the fifth exam.MAIN MEASURES
Primary exposures were T2D (fasting glucose?≥?7 mmol/L or taking diabetes medications) and obesity status (BMI?≥?30 kg/m2) of social contacts at a prior exam. Primary outcome was incident T2D in participants.KEY RESULTS
Incident T2D was associated with having a social contact with diabetes (OR 1.32, p?=?0.004) or with obesity (OR 1.21, p?=?0.004). In stratified analyses, incident T2D was associated with diabetes in siblings (OR 1.64, p?=?0.001) and obesity in spouses (OR 1.54, p =?0.0004). The associations between diabetes and obesity in social contacts and an individual’s incident diabetes risk were stronger in individuals with a high diabetes genetic risk score.CONCLUSIONS
T2D and obesity in social contacts, particularly siblings and spouses, were associated with an individual’s risk of incident diabetes even after accounting for parental T2D history. Assessing risk factors in an individual’s siblings and spouses can inform T2D risk; furthermore, social network based lifestyle interventions involving spouses and siblings might be a novel T2D prevention approach.96.
Using albumin and crystalloid as the only replacement fluids, the effect of partial plasma exchange on the removal and recovery of normal plasma constituents was studied. The results of 30 procedures on 10 individuals were evaluated. Four patterns of removal are described: reduction in the concentration of fibrinogen and C3 were greater than would be expected based upon the extent of the exchange, while IgG, IgM, cholesterol, alkaline phosphatase and SGPT were removed as expected. Reduction of serum glutamicoxalacetic transaminase (SGOT), lactate dehydrogenase (LDH), amylase, and creatine phosphokinase (CPK) averaged 17% less, and uric acid, calcium and K+ averaged 53% less than expected. Concentrations of HCO-3 and glucose did not change. The mean recovery for all constituents except fibrinogen, C3, cholesterol. IgG and IgM was near 100% at 48-72 hr postpheresis. The 72-hr recovery of fibrinogen and complement was 66% and 60%, respectively. Cholesterol recovery was also slow, requiring a minimum of 1 wk to reach prepheresis levels. Measured at a time when quantitative IgM levels were still reduced, alloantibody agglutinating activity (anti-A and anti-B) in a postpheresis sample exceeded prepheresis agglutinating activity. These data demonstrated that, depending upon quantity and frequency of pheresis, partial plasma exchange using albumin replacement may cause progressive marked reduction in concentrations of immunoglobulin, complement, fibrinogen, and cholesterol. Furthermore, newly synthesized antibody may have increased biologic activity. 相似文献
97.
JB Epstein 《Oral diseases》1997,3(Z1):S124-S128
Kaposi's sarcoma (KS) is the most common neoplastic disease in patients with disease due to human immunodeficiency virus (HIV), and oral KS (OKS) is the commonest oral neoplasia. OKS has been managed by local excision, intralesional chemotherapy regional radiotherapy, and systemic chemotherapy. Comparison between studies is difficult as the severity of oral involvement is not well defined in most studies. This paper reviews the approach to the management of OKS and also presents a proposal for the clinical staging of OKS. Clinical staging of OKS will facilitate comparisons of outcomes of treatment of OKS and improve our understanding of the natural history of the neoplasia, which has varied presentation and rates of progression. 相似文献
98.
BC SHARMA RP SINGH YK CHAWLA KL NARASIMHAN KLN RAO SK MITRA JB DILAWARI 《Journal of gastroenterology and hepatology》1997,12(8):582-584
Shunt surgery is considered to be the treatment of choice in patients with non-cirrhotic portal hypertension. There is little data on the effect of side-to-side lieno-renal (SSLR) shunt on oesophageal variceal size, splenic size and splenic pulp pressure (SPP) in patients with non-cirrhotic portal hypertension. We evaluated pre- and postoperatively endoscopic grading of varices, splenic size and SPP for predicting shunt patency in 86 patients with non-cirrhotic portal hypertension: 56 with extrahepatic portal venous obstruction (EHPVO) and 30 with non-cirrhotic portal fibrosis (NCPF). The EHPVO patients with patent shunts (n= 47) showed significant reduction in SPP (pre-operative 43.56±7.9 vs postoperative 29.96±7.7 cm of saline), splenic size (6.5±2.8 vs 4.00±2.6 cm below costal margin) and varices grades (2.96±0.5 vs 0.92±0.8). Patients with blocked shunt (n= 9) did not show significant reduction in SPP and varices grades. However, there was reduction in spleen size (8.6±3.0 vs 6.3±4.3). In the NCPF group, 28 had patent shunts and showed significant reduction in SPP (46.3±13.5 vs 33.8±7.6 cm of saline), splenic size (9.1±3.3 vs 6.8±4.6 cm below costal margin) and varices grades (2.8±0.7 vs 1.05±0.96). As only two patients with NCPF had blocked shunts, no statistical comparison between patients with patent and patients with blocked shunts could be done. In conclusion, following SSLR, there is a significant reduction in SPP and varices grades in patients with patent shunts. Endoscopic grading of varices can be used to predict shunt patency. However, spleen size is not a good criteria for predicting shunt patency. 相似文献
99.
100.
MR Carvalho ; MA Krieger ; E Almeida ; W Oelemann ; MA Shikanai-Yassuda ; AW Ferreira ; JB Pereira ; A Saez-Alquezar ; PE Dorlhiac-Llacer ; DF Chamone ; et al. 《Transfusion》1993,33(10):830-834
Blood transfusion is one of the principal routes of transmission of Chagas' disease, a major endemic disease in Latin America. Methods for blood screening are not accurate and may yield false results that lead to high social and economic costs. This study compares two methods of diagnosing Chagas' disease (indirect immunofluorescence and hemagglutination) and several enzyme-linked immunosorbent assays (ELISAs) with regard to specificity and sensitivity, by using human sera with known serologic and parasitologic characteristics, as well as samples with discrepant results on conventional serologic tests. An ELISA using recombinant antigens showed no cross-reactivity with sera that were positive for other diseases. All evaluated ELISAs performed well, and their use may lead to a reduction of more than 50 percent in the number of discordant sera. Further improvements are needed in view of the complexity of the serologic diagnosis of Chagas' disease. 相似文献