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   571篇
  免费   56篇
  国内免费   5篇
耳鼻咽喉   8篇
儿科学   23篇
妇产科学   13篇
基础医学   43篇
口腔科学   11篇
临床医学   81篇
内科学   129篇
皮肤病学   21篇
神经病学   15篇
特种医学   97篇
外科学   59篇
综合类   22篇
预防医学   40篇
眼科学   12篇
药学   15篇
肿瘤学   43篇
  2023年   6篇
  2021年   15篇
  2020年   8篇
  2019年   5篇
  2018年   14篇
  2017年   16篇
  2016年   10篇
  2015年   17篇
  2014年   30篇
  2013年   40篇
  2012年   8篇
  2011年   13篇
  2010年   32篇
  2009年   19篇
  2008年   20篇
  2007年   19篇
  2006年   13篇
  2005年   9篇
  2004年   10篇
  2003年   4篇
  2002年   11篇
  2001年   13篇
  2000年   5篇
  1999年   15篇
  1998年   25篇
  1997年   32篇
  1996年   29篇
  1995年   17篇
  1994年   19篇
  1993年   12篇
  1992年   9篇
  1991年   3篇
  1990年   6篇
  1989年   9篇
  1988年   8篇
  1987年   8篇
  1986年   8篇
  1985年   12篇
  1984年   9篇
  1983年   5篇
  1982年   13篇
  1981年   7篇
  1980年   11篇
  1979年   5篇
  1978年   6篇
  1977年   8篇
  1976年   6篇
  1975年   5篇
  1973年   3篇
  1970年   3篇
排序方式: 共有632条查询结果,搜索用时 0 毫秒
91.
A patient with a lifelong bleeding disorder was diagnosed as having Type II von Willebrand disease. The larger multimers of von Willebrand factor were absent from her plasma but present in platelets. A high- resolution electrophoretic technique was used to study the complex structure of individual von Willebrand factor multimers. In normal plasma, each multimer could be resolved into five bands: a more intense central one and four less intense, two moving faster and two slower than the central band. In normal platelets, each multimer could also be resolved into five bands. The central one had a mobility similar to that in plasma, whereas the four satellite bands had a mobility that differed from that of the corresponding plasma bands. In the patient, platelet von Willebrand factor antigen content and ristocetin cofactor activity were normal, and von Willebrand factor showed the same structure of individual multimers as seen in normal platelets. On the other hand, plasma von Willebrand factor antigen and ristocetin cofactor activity were decreased, and the structure of individual von Willebrand factor multimers was different from that of normal plasma and similar to that seen in normal and patient's platelets. After infusion of 1-deamino-8-D-arginine vasopressin, the largest von Willebrand factor multimers, as well as new satellite bands with a mobility similar to those in normal plasma, appeared in the patient plasma, and the levels of von Willebrand factor antigen and ristocetin cofactor activity became normal. Yet no relevant change in the prolonged bleeding time was observed. This new variant of von Willebrand disease, therefore, is characterized by the presence of a dysfunctional von Willebrand factor molecule that exhibits unique structural abnormalities in plasma but appears to be normal in platelets. The designation of Type IIF is proposed for this type of von Willebrand disease in accordance with the terminology that has been previously used.  相似文献   
92.
Diet,fecal bile acids,and neutral sterols in carcinoma of the colon   总被引:4,自引:0,他引:4  
Increased concentrations of fecal bile acids and neutral sterols or their degradation products have been linked to certain diets and are implicated in colonic carcinogenesis. We measured fecal bile acid and neutral sterol concentrations by thin-layer and gas-liquid chromatography in 15 patients with colonic adenocarcinoma, 23 controls, and 16 patients with nongastrointestinal cancer. We compared these results with dietary intake. Detailed dietary histories showed no differences among the groups in the ingestion of calories, protein, fiber, fat, or carbohydrate. A wide variation in fecal concentration of individual bile acids and neutral sterols was found within each group, but no significant differences in the total bile acid or total neutral sterol per gram dry weight feces were found. Decreased coprostanol, coprostanone, and lithocholic acid excretion was found in the colon cancer group compared with controls. The fecal excretion of all bile acids and neutral sterols was lower significantly in the nongastrointestinal cancer patients with liver metastases as compared with those without. We conclude that total bile acid and total neutral sterol excretion is similar in the three groups, all ingesting similar diets. We cannot confirm reported increased excretion of total bile acids nor excessive bacterial conversion to degradation products in colonic cancer patients. Hepatic metastases correlate with decreased fecal excretion of both bile acids and neutral sterols, which may be due to diminished hepatobiliary excretion.  相似文献   
93.
We observed the presence of a new autoantibody, anti-erythrocyte protein 4.1, in a patient with autoimmune hemolytic anemia (AIHA). Western blotting analysis revealed that IgG from the patient's plasma reacted with erythrocyte protein 4.1. However, among other patients with hemolytic diseases (six having AIHA and three each having either hereditary spherocytosis, elliptocytosis, or lead poisoning) as well as among control subjects, no antibody activity to protein 4.1 was observed. In addition to the anti-protein 4.1 antibody, two different kinds of anti-erythrocyte antibodies were detected by conventional serological studies in this patient. One of them was an anti-Ena-like antibody in the eluate from the patient's erythrocytes, while another was the anti-S-specific antibody in the plasma. An elution study and an absorption study using S antigen-positive erythrocytes demonstrated that the anti-protein 4.1 antibody differed from both the anti-Ena-like antibody and the anti-S antibody. Familial analysis of the patient revealed the same antibody in her brother, who did not have hemolytic anemia. These results demonstrate that anti-protein 4.1 antibody is considered to be included in the spectrum of anti-cytoskeleton autoantibodies, which have been observed in patients having increased cell lysis as well as in healthy subjects.  相似文献   
94.
BACKGROUND: Several instruments can be used to identify patients with an unfavourable course of low back pain in general practice. However, it is unclear which instrument is the predictor of outcome. AIM: To compare the predictive performance (that is, calibration and discrimination) of risk estimation by GPs with assessments using the Orebro Musculoskeletal Pain Screening Questionnaire, the Low Back Pain Perception Scale (LBPPS), and a prediction rule developed for this purpose. Design of study: A prospective cohort study with 1-year follow-up. SETTING: General practice in The Netherlands. METHOD: The outcome 'unfavourable course of low back pain' was defined as having no clinically important improvement at minimally 50% of the measurements at 6, 13, 26, and 52 weeks. Logistic regression analyses were used to study associations between potential predictors and outcome. RESULTS: In total, 60 GPs recruited 314 patients to the study (16 patients were excluded from analysis due to missing data on the course of low back pain). Over a third of patients (112/298) showed an unfavourable course of low back pain on follow-up. Risk estimation by GPs, the Orebro questionnaire, the LBPPS, and the prediction rule had discriminative ability (area under the curve) of 0.59 (95% CI [confidence intervals] = 0.52 to 0.66); 0.61 (95% CI = 0.54 to 0.67); 0.59 (95% CI = 0.52 to 0.66); and 0.75 (95% CI = 0.69 to 0.81) respectively. The prediction rule included history of low back pain, self-perceived risk to develop chronic low back pain, no solicitous responses of the patient's partner (as reported by the patient), frequent walking at work, and 'pain catastrophising'. CONCLUSION: Although the prediction rule performed best with regard to calibration and discrimination, it needs to be externally validated. Risk estimation by GPs performs as well as other instruments and, at present, seems to be the best available option.  相似文献   
95.
Chemerin is an adipokine that regulates adipogenesis and metabolic functions of mature adipocytes mainly through the activation of chemokine‐like receptor 1 (CMKLR1). Elevated levels of chemerin have been found in individuals with obesity, type 2 diabetes, and osteoporosis. This adipokine was identified as an inflammatory and metabolic syndrome marker. Considering that the association between metabolic syndrome and bone health remains unclear, the present study aimed to clarify the role of chemerin in the pathophysiology of bone loss induced by dyslipidemia, particularly modulating osteoclastogenesis. In vitro analyses showed a downregulation of CMKLR1 at the early stage of differentiation and a gradual increase at late stages. Strikingly, chemerin did not modify osteoclast differentiation markers or osteoclast formation; however, it increased the actin‐ring formation and bone resorption activity in mature osteoclasts. The increased bone resorption activity induced by chemerin was effectively inhibited by CMKLR1 antagonist (CCX832). Chemerin boosting mature osteoclast activity involves ERK5 phosphorylation. Moreover, two models of dyslipidemia (high‐fat diet [HFD]‐treated C57/BL6 and db/db mice) exhibited significantly increased level of chemerin in the serum and gingival tissue. Morphometric analysis showed that HFD‐treated and db/db mice exhibited increased alveolar bone loss compared to respective control mice, which was associated with an up‐regulation of chemerin, CMKLR1 and cathepsin K mRNA expression in the gingival tissue. The treatment of db/db mice with CCX832 effectively inhibited bone loss. Antagonism of chemerin receptor also inhibited the expression of cathepsin K in the gingival tissue. Our results show that chemerin not only increases osteoclasts activity in vitro, but also that increased level of chemerin in dyslipidemic mice plays a critical role in bone homeostasis. © 2016 American Society for Bone and Mineral Research.  相似文献   
96.
97.
We sought to evaluate whether residency application statements regarding expected career paths are accurate predictors of early postresidency career paths. We evaluated 162 residents who completed a categorical medicine residency at Georgetown University Hospital between 1990 and 1998 to determine if their stated career plans (generalist practice, subspecialization, or undecided) at application predicted activity immediately after residency. Of 130 residents with defined postresidency plans at application, most 78 (60%) followed those career paths after graduation; 18 (67%) of 27 pursued their initial interest in generalist practice, and 60 (58%) of 103 pursued their stated interest in subspecialty training. We also noted a movement of residents toward generalism (79 [49%] of 162), despite low initial interest (27 [17%] of 162).  相似文献   
98.
Purpose of ReviewWith increased understanding of the biomechanical function of the acetabular labrum, more attention has been directed towards surgical techniques that preserve or restore normal joint anatomy. While labral repair has been shown to produce superior outcomes to labral debridement, repair is not always possible in the setting of severe labral intrasubstance tearing or deficiency. These patients were previously left without suitable arthroscopic treatment options.Recent FindingsLabral reconstruction is an emerging procedure that has been shown to offer promising outcomes for traditionally difficult-to-treat hip pathology. Short- and mid-term follow-up studies have consistently demonstrated significant improvement in patient-reported outcomes, function, and patient satisfaction postoperatively, often despite less favorable preoperative characteristics.SummaryLabral reconstruction is a viable arthroscopic treatment option that has been shown to reliably produce clinically meaningful results in patients with severe labral pathology that is not amenable to repair/refixation or augmentation.  相似文献   
99.
Abdominal trauma: use of oral contrast material for CT is safe   总被引:2,自引:0,他引:2  
  相似文献   
100.
Color Doppler imaging (CDI) can demonstrate the relative direction and velocity of blood flow in color, superimposed on a conventional gray-scale ultrasound image that depicts stationary tissue. Twenty-five infants were studied with portable CDI in the coronal, sagittal, and axial planes. Bilateral antegrade flow was noted in the anterior, middle, and posterior cerebral arteries in all patients. Multiplanar CDI can image flow in the circle of Willis and its tributaries and branches.  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