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   1571篇
  免费   70篇
  国内免费   4篇
耳鼻咽喉   20篇
儿科学   28篇
妇产科学   20篇
基础医学   176篇
口腔科学   32篇
临床医学   83篇
内科学   546篇
皮肤病学   83篇
神经病学   146篇
特种医学   20篇
外科学   185篇
综合类   12篇
一般理论   2篇
预防医学   108篇
眼科学   13篇
药学   79篇
肿瘤学   92篇
  2023年   13篇
  2022年   5篇
  2021年   34篇
  2020年   14篇
  2019年   46篇
  2018年   51篇
  2017年   24篇
  2016年   26篇
  2015年   35篇
  2014年   38篇
  2013年   63篇
  2012年   146篇
  2011年   130篇
  2010年   81篇
  2009年   54篇
  2008年   115篇
  2007年   104篇
  2006年   104篇
  2005年   106篇
  2004年   100篇
  2003年   96篇
  2002年   88篇
  2001年   32篇
  2000年   23篇
  1999年   22篇
  1998年   7篇
  1997年   5篇
  1996年   4篇
  1995年   4篇
  1994年   3篇
  1993年   2篇
  1992年   6篇
  1991年   5篇
  1990年   4篇
  1989年   9篇
  1988年   6篇
  1987年   6篇
  1985年   4篇
  1984年   3篇
  1983年   3篇
  1973年   1篇
  1972年   1篇
  1971年   1篇
  1969年   1篇
  1967年   6篇
  1966年   1篇
  1964年   1篇
  1962年   4篇
  1960年   1篇
  1958年   1篇
排序方式: 共有1645条查询结果,搜索用时 15 毫秒
91.
Deep venous thrombosis (DVT) and pulmonary embolism (PE) are entities with a relative high frequency in post-surgical patients and can occur immediately after the surgical procedure or even two or three weeks after the surgical event. In the United States and Europe, DVT is present in over 5 million events each year, while PE is present in over 500,000 cases. The purpose of this study is to review the cases that undergo surgery during a period of three months (1,500 cases), from June 15th to September 15th, 2003, at the Angeles of Pedregal Hospital in Mexico City, in order to evaluate the type of risk that each one represents (International Consensus, 1997 ACCP, and the 2000 Mexican Consensus over venous thromboembolism (VTE) questionnaire), and the prophylaxis applied in each case, to be compared with international standards. The Angeles of Pedregal Hospital maintains a general prophylactic standard with its patients equivalent in number to the international standard; however, there is deficiency in the measures taken in orthopedic, high-risk, and very high-risk patients, where prophylaxis was low. It has also been called to our attention that the prophylactic measures taken were insufficient, both in the type of measure that was chosen and the combination of those that were applied, which in relation to the international recommendations were extremely low.  相似文献   
92.
A 37-year-old primiparous woman with syringomyelia and Arnold-Chiari type I malformation was scheduled to undergo elective caesarean section for a fetus in the breech presentation. Caesarean section was performed under general anaesthesia without complications; all we observed was an exaggerated response to atracurium. The patient was discharged home 7 days after the operation without neurological deterioration. General anaesthesia was chosen in this patient to avoid any spinal manipulation that could increase intracranial pressure or reduce intraspinal pressure and cause deterioration of neurological symptoms. Syringomyelia is a progressive myelopathy characterised by cystic degeneration within the spinal cord, which causes severe neurological deficits. The anaesthetic management is discussed.  相似文献   
93.
Background. Aberrations of the p53 gene and overexpression of its protein are widely recognized markers of malignancy including oral squamous cell carcinomas. This study was performed to evaluate the relationship of immunoexpression of p53 protein in series of 91 squamous cell carcinomas of the oral cavity with clinicopathologic parameters and to investigate whether p53 immunoexpression might influence the clinical outcome of the disease. Methods. From a group of 287 consecutive patients, 91 surgically treated ones were randomly selected. P53 protein expression was investigated by means of immunohistochemistry. Clinical and histopathologic data were gathered, and the patient survival was analyzed. Results. Of the oral carcinomas, 52.7% (n = 48) overexpressed p53, using a threshold of 10% stained cell nuclei. There was a negative correlation of p53 immunoexpression with a histologic grade of differentiation (r = ?0.236, p = .06) but not with clinical variables. Overall survival rate was 59% at 5 years. In univariate analysis, tumor size, node status, and advanced clinical stage were significantly associated with shortened overall survival. In patients without neck node metastases, p53 showed a strong correlation with survival (p = .01). In multivariate analysis performed only on N0 patients, tumor extension and p53 immunoexpression were found to be the only independent prognostic parameters with relative risks of 1.9 and 4.3, respectively. Conclusions. A strong relationship was observed between p53 immunoexpression and poor prognosis in patients with oral squamous cell carcinomas without neck node metastases. © 2004 Wiley Periodicals, Inc. Head Neck 26: 22–30, 2004  相似文献   
94.
95.
96.
97.
OBJECTIVES: Calorie restriction has been associated with anorexia in growing individuals, but the mechanisms involved are not known. Also, the effects of carbohydrates and lipid restriction in growing individuals were not studied. The aim of this study was to determine whether 66% calorie restriction (lipids and carbohydrates) differentially affects growing rats of the Wistar or Lewis strains. METHODS: Growing male Wistar and Lewis rats were subjected to 66% calorie restriction for 4 weeks. Plasma prolactin, growth hormone (GH), and adrenocorticotropic hormone (ACTH) levels were measured by specific radioimmunoassays. Likewise, lymphocytes from submaxillary lymph nodes were aseptically obtained to study absolute number of lymphocytes, cell surface markers (CD4+, CD8+, CD4+CD8+, B, and T cells), and proliferation. RESULTS: The body weight gain was lower in Lewis than in Wistar rats and was blunted in both strains by calorie restriction. Wistar and Lewis rats exhibited differential patterns of plasma prolactin, ACTH, and GH levels as well as proliferative capacities of T and B cells and their distribution in the submaxillary lymph nodes. Calorie restriction increased plasma prolactin and ACTH levels in Lewis as compared with Wistar rats. However, the plasma GH levels were diminished in both strains of rats by calorie restriction. All changes in plasma prolactin ACTH and GH levels seemed to correlate with the modifications observed in the distributions of T and B subsets in the submaxillary lymph nodes as well as in their proliferative capacity. CONCLUSIONS: Calorie restriction differentially modifies the secretory patterns of prolactin, GH, and ACTH in Lewis and in Wistar rats. These changes may explain, at least in part, the associated modifications in the proliferative capacity of submaxillary lymph node lymphocytes and in their distribution.  相似文献   
98.
99.
Lip cancer is the most frequent malignant neoplasm of the oral cavity; however, there is no information available on the incidence of this type of cancer in Mexico. This study provides information about the clinico-pathological features of lip cancer patients admitted at a cancer hospital in Mexico City during an 11-year period and describes the treatment modalities performed and their results. A total of 113 patients were studied. There were 74 men (65.5%) and 39 women (34.5%), ranging in age from 14 to 106 years (mean 70 years). In 53 cases (46.9%) an association was found between the disease and chronic sun exposure. Additionally, positive smoking antecedents were recorded in 58 cases (51.3%). As 15 patients were followed for less than 1 month, they were excluded for further analysis. There were 82 cases (83.7%) of squamous cell carcinoma, 10 (10.2%) basal cell carcinomas, and one case (1%) each of adenocarcinoma NOS, melanoma, adenoid cystic carcinoma, Merkel cell carcinoma, lymphoepithelioma and angiosarcoma. We observed an incidence of malignant neoplasms in the upper lip of 33.7%, which is higher than most of the published series and may be due to the fact that in this series we included all histological types of lip cancers. Fifty percent of the cases were found in stages III and IV. Cervical lymph node metastases were found in 21% of patients with no previous treatment, and they developed in 5.3% after treatment. Our data suggest that tumoral size is directly related to the possibility of developing node metastases, as none of them occurred in patients T1, whereas 10 (62.5%) of the patients in T4 presented them. Seven deaths were documented (7.1%), five of which corresponded to squamous cell carcinoma, one to Merkel cell carcinoma, and one to adenocarcinoma. Deaths were directly related to the disease in six cases, and one patient died due to surgical complications. Distant metastases were found in only two patients, one of which coursed with an adenocarcinoma and the other with a Merkel cell carcinoma. Based on the present results, we suggest that the differences encountered with respect to other series, particularly the higher incidence found in women, the frequent presentation of this type of neoplasms in the upper lip, the wide variety of histopathological diagnoses and the high frequency of cases with cervical lymph node affection, should lead us to search for multi-modal treatment alternatives in this population.  相似文献   
100.
OBJECTIVE: To assess the potential value of ductus venosus Doppler studies in the detection of fetal aneuploidy on measurement of nuchal translucency. METHODS: The pulsatility index for veins (PIV) and the lowest velocity during atrial contraction (A-wave) were determined in the fetal ductus venosus in 3382 consecutive pregnancies at 10 to 14 weeks and studied from December 1996 to December 2001. Nuchal translucency was also measured. The population studied included 1664 pregnancies at high risk and 1718 at low risk for fetal aneuploidy. RESULTS: In relation to the prenatal detection of trisomy 21, the ductus venosus PIV was increased in 75% (36/48), the A-wave was decreased in 58% (28/48), and nuchal translucency was enlarged in 81% (39/48) of the trisomy 21 fetuses [71% (22/31) when nuchal translucency referrals were excluded]. The corresponding figures for trisomies 18 and 13 were 71, 58 and 83%, respectively, being 33, 33 and 33% for other unbalanced anomalies. CONCLUSION: There is a high proportion of fetuses with trisomies 21, 18 and 13 (around 75%) in which the ductus venosus PIV is increased (above the 95th percentile) at 10 to 14 weeks, this proportion being similar to that observed for increased nuchal translucency measurement.  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