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   1127篇
  免费   69篇
  国内免费   13篇
耳鼻咽喉   7篇
儿科学   13篇
妇产科学   26篇
基础医学   141篇
口腔科学   42篇
临床医学   106篇
内科学   214篇
皮肤病学   37篇
神经病学   161篇
特种医学   34篇
外科学   263篇
综合类   5篇
预防医学   48篇
眼科学   2篇
药学   53篇
肿瘤学   57篇
  2023年   11篇
  2022年   21篇
  2021年   44篇
  2020年   30篇
  2019年   51篇
  2018年   53篇
  2017年   29篇
  2016年   38篇
  2015年   37篇
  2014年   55篇
  2013年   67篇
  2012年   101篇
  2011年   95篇
  2010年   50篇
  2009年   26篇
  2008年   59篇
  2007年   52篇
  2006年   55篇
  2005年   56篇
  2004年   50篇
  2003年   41篇
  2002年   33篇
  2001年   19篇
  2000年   27篇
  1999年   15篇
  1998年   6篇
  1997年   3篇
  1996年   4篇
  1995年   3篇
  1994年   3篇
  1993年   6篇
  1992年   5篇
  1991年   7篇
  1990年   9篇
  1989年   9篇
  1988年   2篇
  1987年   7篇
  1985年   4篇
  1984年   3篇
  1982年   3篇
  1980年   1篇
  1979年   1篇
  1977年   1篇
  1975年   3篇
  1974年   2篇
  1973年   2篇
  1970年   1篇
  1966年   4篇
  1965年   2篇
  1964年   1篇
排序方式: 共有1209条查询结果,搜索用时 15 毫秒
61.
The hepatoprotective activity of the aqueous extract of the shells of pecan nut was investigated against ethanol-induced liver damage. This by-product of the food industry is popularly used to treat toxicological diseases. We evaluated the phytochemical properties of pecan shell aqueous extract (AE) and its in vitro and ex vivo antioxidant activity. The AE was found to have a high content of total polyphenols (192.4 ± 1.9 mg GAE/g), condensed tannins (58.4 ± 2.2 mg CE/g), and antioxidant capacity, and it inhibited Fe2+-induced lipid peroxidation (LP) in vitro. Rats chronically treated with ethanol (Et) had increased plasmatic transaminases (ALT, AST) and gamma glutamyl transpeptidase (GGT) levels (96%, 59.13% and 465.9%, respectively), which were effectively prevented (87; 41 and 383%) by the extract (1:40, w/v). In liver, ethanol consumption increased the LP (121%) and decreased such antioxidant defenses as glutathione (GSH) (33%) and superoxide dismutase (SOD) (47%) levels, causing genotoxicity in erythrocytes. Treatment with pecan shell AE prevented the development of LP (43%), GSH and SOD depletion (33% and 109%, respectively) and ethanol-induced erythrocyte genotoxicity. Catalase activity in the liver was unchanged by ethanol but was increased by the extract (47% and 73% in AE and AE + Et, respectively). Therefore, pecan shells may be an economic agent to treat liver diseases related to ethanol consumption.  相似文献   
62.
We analyzed trends over time and determinants of late diagnosis of HIV infection among people diagnosed with AIDS in 1986 to 1998 in a tertiary care center in Rome, Italy. Information on the date of a first HIV test was collected prospectively, in addition to data routinely collected for AIDS reporting. Patients with AIDS were defined as "late testers" if the time interval between first positive HIV test result and AIDS diagnosis was < or = 3 months. Overall, 503 people with AIDS of 1977 included in the analysis (25.4%) were late testers. the proportion of late testers decreased from 62.5% in 1986 to 16% in 1995. Thereafter, this proportion increased to 20.5% in 1996, 33.7% in 1997, and 36.6% in 1998. In multivariate analysis, the following variables were significantly associated with late testing: AIDS diagnosis in years 1986 to 1993 or 1997 to 1998 compared with 1995, male gender, age > or = 45 years, men who have sex with men, heterosexual contacts, or having unknown transmission mode compared with intravenous drug users, and being born outside Italy. Since 1996, the overall number of AIDS cases diagnosed at our center began to decrease whereas the number of late-testing AIDS patients did not decrease, resulting in an increasing proportion of late testers during the last 3 years of the study. This findings may reflect the effect of combination antiretroviral therapy in slowing progression to AIDS of HIV-infected persons aware of their status. A relevant number of people still discover their HIV infection late and may therefore miss treatment opportunities. New testing strategies are needed to reach more people who engage in high-risk behaviors, especially those at risk for sexual transmission, and those born outside Italy.  相似文献   
63.
Ninety patients with cervical intraepithelial neoplasia (CIN) were randomly assigned to loop excision (n = 38) or cold-knife conization (n = 52). All specimens were well evaluable at histology. The average width of the lesions at histology was 10.2 and 9.7 mm, respectively (ns). The average weight of the specimens was 2.6 and 5.6 g (P < 0.01) and the average depth was 9.2 and 15.8 mm (P < 0.01), respectively. The distance between the cervical resection margin and CIN was 14 mm after loop excision and 24 mm after cold-knife conizatiun (P < 0.06). The margins of the specimen were not clear of disease in 8 patients after loop excision and in 12 patients after conization (ns). Two patients after loop excision and in three patients after cold-knife conization had postoperative bleeding. The results suggest that, compared with cold-knife conization, loop excision removes less healthy tissue without reducing the chances for cure.  相似文献   
64.
Bone morphogenetic proteins (BMPs) are low molecular weight glycoproteins that play a vital role in the development and maturation of skeletal tissue. Bone morphogenetic protein-induced mesenchymal cell recruitment and differentiation leads to the formation of chondroblasts and osteoblasts leading to the formation of de novo bone. Overwhelming pre-clinical and clinical evidence has suggested a promising role for BMPs for anterior and posterolateral spinal fusion. Strength of this approach lies in the potential ability of these growth factors to reverse inhibitory conditions common in the clinical setting and enabling predictable fusion. However, several issues related to carriers, costs, and dosages still need to be consecutively addressed. Gene therapy techniques producing in vivo osteoinductive factors and utilizing minimally invasive approaches are attractive options being developed for the future.  相似文献   
65.
Aneurysm of the main pulmonary artery is a rare anomaly with a poorly understood pathogenesis. We report the successful surgical resection and repair of a pulmonary artery aneurysm using aneurysmectomy and replacement of the pulmonary artery with Dacron, a procedure with excellent longterm outcome that eliminates the risk of recurrence. The 65-year-old male patient presented with a marked decrease in exercise tolerance and worsening dyspnea. He had a history of pulmonary stenosis diagnosed during childhood, episodic shortness of breath beginning during his teenage years, hypertension, and smoking. On physical examination, the patient appeared generally well. Computed tomographic scan of the chest revealed an 8-cm aneurysm involving the main pulmonary artery and pulmonary artery bifurcation. Coronary angiography showed a massive aneurysm of the main and left pulmonary arteries, with mild dilation of the proximal right pulmonary artery. Surgery was performed through a median sternotomy with the use of normothermic, bicaval cardiopulmonary bypass. The aneurysm of the main pulmonary artery and dilated bifurcation of the pulmonary artery was excised and reconstruction was performed using a 22-mm Dacron graft. The patient's postoperative course was uneventful. He was discharged to home on postoperative day 5 and was well at 1-month follow-up.  相似文献   
66.
67.
68.
Patients with pre-existing coagulopathies who undergo surgical interventions are at increased risk for bleeding complications. This risk is especially true in cardiac surgical procedures with cardiopulmonary bypass (CPB) because of the necessity for heparinization and the use of the extracorporeal circuits, which have destructive effects on most of the blood components. In this review, cases of cardiac surgeries in patients with certain pre-existing coagulopathies are summarized, which could shed a light on future managements of such patients undergoing cardiac procedures with CPB. Pre-existing coagulopathies include antithrombin III deficiency, heparin-induced thrombocytopenia, cancer, factor XII deficiency, hemophilia, idiopathic thrombocytopenic purpura, protein S deficiency, and drug-induced platelet inhibition. In summary, pre-existing coagulopathy in patients undergoing open-heart surgeries, if not recognized and appropriately managed, can cause serious complications. Management of patients undergoing cardiac procedures should include a routine coagulation work-up and a thorough past medical history examination. If any of the foregoing is abnormal, further evaluation is warranted. Proper diagnosis and management of the pre-existing coagulopathy disorders is of crucial importance to the surgical outcome and long-term morbidity.  相似文献   
69.
70.
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