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   3800篇
  免费   195篇
  国内免费   13篇
耳鼻咽喉   110篇
儿科学   145篇
妇产科学   54篇
基础医学   485篇
口腔科学   71篇
临床医学   227篇
内科学   993篇
皮肤病学   49篇
神经病学   322篇
特种医学   117篇
外国民族医学   4篇
外科学   484篇
综合类   16篇
预防医学   248篇
眼科学   50篇
药学   323篇
中国医学   7篇
肿瘤学   303篇
  2023年   25篇
  2022年   36篇
  2021年   87篇
  2020年   58篇
  2019年   76篇
  2018年   91篇
  2017年   73篇
  2016年   69篇
  2015年   95篇
  2014年   105篇
  2013年   129篇
  2012年   209篇
  2011年   236篇
  2010年   133篇
  2009年   114篇
  2008年   214篇
  2007年   216篇
  2006年   179篇
  2005年   166篇
  2004年   153篇
  2003年   123篇
  2002年   128篇
  2001年   107篇
  2000年   86篇
  1999年   89篇
  1998年   30篇
  1997年   34篇
  1996年   26篇
  1995年   33篇
  1994年   24篇
  1993年   20篇
  1992年   60篇
  1991年   52篇
  1990年   53篇
  1989年   56篇
  1988年   53篇
  1987年   54篇
  1986年   42篇
  1985年   30篇
  1984年   24篇
  1983年   27篇
  1981年   22篇
  1979年   36篇
  1978年   15篇
  1975年   17篇
  1974年   22篇
  1973年   18篇
  1971年   18篇
  1970年   14篇
  1968年   16篇
排序方式: 共有4008条查询结果,搜索用时 31 毫秒
941.
BACKGROUND: Although an association between primary biliary cirrhosis and coeliac disease has recently been reported in Northern Europe, there are still conflicting data concerning this issue. AIM: To evaluate both the prevalence of coeliac disease in a series of primary biliary cirrhosis patients and that of antimitochondrial antibodies in a series of adult biopsy proven coeliac disease patients from Northern Italy. PATIENTS AND METHODS: A total of 87 primary biliary cirrhosis patients (79 female, 8 male) were screened for both IgA-transglutaminase antibodies and antiendomysium antibodies and, in those with either IgA-transglutaminase antibodies or antiendomysium antibodies positivity, upper endoscopy with distal duodenum biopsy was offered. In those who refused upper endoscopy, the intestinal permeability test with lactulose/mannitol excretion was performed. RESULTS: Antiendomysium antibodies positivity was detected in 3 subjects (3.4%), all of whom had serum IgA-transglutaminase antibodies above the normal range, and fulfilled the diagnosis of coeliac disease. Of 21 other patients with serum IgA-transglutaminase antibodies above the normal range, 17 underwent upper endoscopy which revealed normal duodenum architecture. The remaining 4 patients underwent the lactulose/mannitol excretion test which was within the normal range. Sera from 108 adult coeliac disease patients were tested for antimitochondrial antibodies and positivity was found in 4 patients (3.7%): all had normal liver biochemistry tests, whereas 2 of them also presented thyroid disease. Antibodies directed to the 74-kDa polypeptide of antimitochondrial antibodies were found in 3 out of 4 antimitochondrial antibodies+ve patients. CONCLUSIONS: These results suggest an association between primary biliary cirrhosis and coeliac disease similar to that observed in the Northern European series. In conclusion, screening for coeliac disease with antiendomysium antibodies in primary biliary cirrhosis is justified, and screening for antimitochondrial antibodies is advisable in adult coeliac disease patients.  相似文献   
942.
In the literature published during the last decade an increased risk of death due to cerebrovascular and cardiovascular events in growth hormone deficient adults has been reported. A partial reversibility of the syndrome following recombinant growth hormone treatment has also been described. Both these factors have contributed to the proposal of growth hormone therapy not only for children but also for adults. Following the initial enthusiasm, the scientific community is now evaluating various clinical experiences held over recent years and weighing up the results. Present day medicine has to take the economic impact of prescribed therapeutic regimens into consideration; in other words the ratio between cost and benefits must be calculated. The relatively recent issuance of the license for the treatment of growth hormone deficiency in adults using recombinant growth hormone does not allow us to evaluate a possible reduction in the risk of death due to cerebrovascular and cardiovascular events in treated subjects. A much longer observational period will be required. Besides the partial reversibility of the syndrome as a consequence of treatment, it is necessary to single out the selection criteria for the choice of treatment. These could also be useful as indicators of the efficacy of the same treatment.  相似文献   
943.
BACKGROUND: Psychiatric symptoms, common in untreated coeliac disease patients, may improve after gluten withdrawal. AIMS: To estimate the incidence of psychiatric disorders in coeliac disease patients on gluten withdrawal and to evaluate: (1) the psychological weight of a chronic disease that involves a restrictive diet and a limited life style; (2) the acceptance of the disease; (3) the effects of both disease and diet on behaviour and quality of life. PATIENTS AND METHODS: Three groups of 100 patients (coeliac disease patients, diabetic patients and healthy controls, respectively) were assessed by means of a professional semi-structured diagnostic interview based on DSM-IV criteria. This interview, together with specific psychiatric questionnaires, ruled out axis I or II psychopathological disturbances. RESULTS: The modified Self-rating Depression Scale and State and Trait Anxiety Inventory Y2 scores were significantly higher in both coeliac and diabetic patients than in healthy controls. The duration of gluten restriction was related to significantly higher modified Self-rating Depression Scale scores in patients with a more recent diagnosis. Quality of life was poorer in both coeliac and diabetic patients than in healthy controls and significantly correlated with anxiety. The Illness Behaviour Questionnaire showed a high psychological and somatic perception of illness in both coeliac and diabetic patients. Its subscale scores correlated significantly with anxiety and depression symptoms. CONCLUSIONS: In coeliac disease, affective disorders should be ascribed to difficulties in adjusting to the chronic nature of the disease rather than directly to the disease itself, thus giving an indication for preventive liaison psychiatric interventions.  相似文献   
944.
Background: The pesticide atrazine does not bind to or activate the classical estrogen receptor (ER), but it up-regulates the aromatase activity in estrogen-sensitive tumor cells. The G protein estrogen receptor (GPR30/GPER) has been reported to be involved in certain biological responses to endogenous estrogens and environmental compounds exerting estrogen-like activity.Objectives: We aimed to evaluate the potential of atrazine to trigger GPER-mediated signaling in cancer cells and cancer-associated fibroblasts (CAFs).Methods and Results: Using gene reporter assays in diverse types of cancer cells, we found that atrazine did not transactivate endogenous ERα or chimeric proteins that encode the ERα and ERβ hormone binding domains. Conversely, atrazine was able to bind to GPER to induce ERK activation and the expression of estrogen target genes, which, interestingly, appeared to rely on both GPER and ERα expression. As a biological counterpart, atrazine stimulated the proliferation of ovarian cancer cells that depend on GPER and ERα, as evidenced by gene silencing experiments and the use of specific signaling inhibitors. Of note, through GPER, atrazine elicited ERK phosphorylation, gene expression, and migration in CAFs, thus extending its stimulatory role to these main players of the tumor microenvironment.Conclusions: Our results suggest a novel mechanism through which atrazine may exert relevant biological effects in cancer cells and CAFs. On the basis of our data, atrazine should be included among the environmental contaminants that may elicit estrogenic activity through GPER-mediated signaling.Citation: Albanito L, Lappano R, Madeo A, Chimento A, Prossnitz ER, Capello AR, Dolce V, Abonante S, Pezzi V, Maggiolini M. 2015. Effects of atrazine on estrogen receptor α– and G protein–coupled receptor 30–mediated signaling and proliferation in cancer cells and cancer-associated fibroblasts. Environ Health Perspect 123:493–499; http://dx.doi.org/10.1289/ehp.1408586  相似文献   
945.
946.

Background

The MPLSer505Asn mutation has been reported to be a cause of hereditary thrombocythemia. Recently, we detected this mutation in a large proportion of children with familial thrombocythemia, suggesting that in Italy the incidence of MPLSer505Asn mutation could be underestimated.

Design and Methods

We extended the search for this mutation to all patients with essential thrombocythemia who had a positive family history for thrombocytosis or essential thrombocythemia. We identified eight Italian families positive for the MPLSer505Asn mutation. Clinical and hematologic data were available for members of seven families, including 21 patients with a proven mutation and 20 relatives with thrombocytosis.

Results

Fifteen major thrombotic episodes, nine of which were fatal, were recorded among 41 patients. The thrombotic manifestation was stroke in four cases, myocardial infarction in seven cases, fetal loss in two cases, deep vein thrombosis of the leg in one case and Budd Chiari syndrome in one case. Almost all patients over 20 years old had splenomegaly and bone marrow fibrosis, while these were rarely observed in patients under 20 years old, suggesting that these manifestations are associated with aging. Finally, the life expectancy of family members with thrombocytosis was significantly shorter than that of members without thrombocytosis (P=0.003).

Conclusions

Patients with familial thrombocytosis caused by a MPLSer505Asn mutation have a high risk of thrombosis and, with aging, develop splenomegaly and bone marrow fibrosis, significantly affecting their life expectancy.  相似文献   
947.
We aimed at evaluating the relationship of lean and fat mass to bone mass in osteoporotic postmenopausal women. We invited 65 women who were being treated at the São Paulo Hospital osteoporosis outpatients’ clinic to participate. Body composition and bone mineral density (BMD) measurements were performed using Dual-energy X-ray absorptiometry methodology (DXA). The mean age and weight were 69.7 ± 6.4 years and 56.3 ± 7.6 kg, respectively. Accordingly to the body mass index (BMI), 52.8% were of normal weight and 47.1% of the patients were overweight. Overweight women had significantly higher bone mass. Similarly, skeletal muscle index (SMI) showed a positive effect on BMD measurements and women with sarcopenia had significantly lower BMD measurements in total femur and femoral neck. In multiple regression analysis only lean mass and age, after adjustments to fat mass and BMI, were able to predict total body bone mineral content (BMC) (R2 = 28%). Also lean mass adjusted to age and BMI were able to predict femoral neck BMD (R2 = 14%). On the other hand, none of the components of the body composition (lean mass or fat mass) contributed significantly to explaining total femur BMD and neither body composition measurements were associated with spine BMD. These findings suggest that lean mass has a relevant role in BMC and BMD measurements. In addition, lower BMI and lean mass loss (sarcopenia) is associated to lower BMC and BMD of femoral neck and total femur and possible higher risk of osteoporotic fracture.  相似文献   
948.
Radiofrequency ablation(RFA)of pancreatic neoplasms is restricted to locally advanced,non-resectable but nonmetastatic tumors.RFA of pancreatic tumors is nowadays an ultrasound-guided procedure performed during laparotomy in open surgery.Intraoperative ultrasound covers the mandatory role of staging,evaluation of feasibility,guidance and monitoring of the procedure.Different types of needle can be used.The first aim in the evaluation of RFA as a treatment for locally advanced pancreatic ductal adenocarcinom...  相似文献   
949.
The aim of the present study is to evaluate the influence of Helicobacter pylori on Bax and Bcl-2 mRNA and protein levels in patients with chronic gastritis and gastric cancer. The study included 217 patients, of which 26 were uninfected; 127 had chronic gastritis and were H. pylori-positive, and 64 had gastric cancer. Bacterial genotypes were evaluated by PCR, and the expression values were determined by quantitative real-time PCR and immunohistochemistry. Our data showed that the up-regulationary effects of H. pylori infection on the pro-apoptotic gene, Bax, were stronger than its induction of Bcl-2; this effect may increase apoptosis in patients with chronic gastritis. In patients with gastric cancer, the up-regulation of the anti-apoptotic gene, Bcl-2, counteracted the pro-apoptotic effects of Bax, leading to a deregulation of apoptosis-associated gene expression, favoring cell proliferation. Thus, the disturbance in Bax and Bcl-2 balance, induced by H. pylori, might be important in gastric cancer development.  相似文献   
950.
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