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   17068篇
  免费   1061篇
  国内免费   200篇
耳鼻咽喉   407篇
儿科学   243篇
妇产科学   342篇
基础医学   2893篇
口腔科学   336篇
临床医学   1304篇
内科学   3450篇
皮肤病学   475篇
神经病学   1281篇
特种医学   1099篇
外科学   2312篇
综合类   87篇
现状与发展   3篇
一般理论   11篇
预防医学   675篇
眼科学   455篇
药学   1346篇
中国医学   161篇
肿瘤学   1449篇
  2024年   12篇
  2023年   146篇
  2022年   386篇
  2021年   706篇
  2020年   295篇
  2019年   482篇
  2018年   573篇
  2017年   441篇
  2016年   655篇
  2015年   923篇
  2014年   1019篇
  2013年   1101篇
  2012年   1656篇
  2011年   1507篇
  2010年   892篇
  2009年   757篇
  2008年   986篇
  2007年   978篇
  2006年   854篇
  2005年   720篇
  2004年   588篇
  2003年   525篇
  2002年   455篇
  2001年   313篇
  2000年   259篇
  1999年   211篇
  1998年   90篇
  1997年   62篇
  1996年   44篇
  1995年   46篇
  1994年   33篇
  1993年   51篇
  1992年   68篇
  1991年   55篇
  1990年   49篇
  1989年   46篇
  1988年   45篇
  1987年   40篇
  1986年   23篇
  1985年   20篇
  1984年   19篇
  1983年   14篇
  1981年   16篇
  1979年   15篇
  1978年   13篇
  1977年   14篇
  1976年   13篇
  1975年   16篇
  1974年   12篇
  1973年   12篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
32.
33.
BackgroudOutcomes of traditional treatment for osteonecrosis of the femoral head (ONFH) are not always satisfactory. Hence, cell-supplementation therapy has been attempted to facilitate necrotic-tissue regeneration. Adipose-derived mesenchymal stem cell (ADMSC) transplantation is potentially advantageous over bone marrow-derived MSC implantation, but its outcomes for ONFH remain unclear. The aim of this study was to determine 2-year radiological and clinical outcomes of culture-expanded autologous ADMSC implantation for ONFH.MethodsEighteen hips with necrotic lesions involving ≥ 30% of the femoral head were included. ADMSCs were harvested by liposuction and culture expanded for 3 passages over 3 weeks. With a 6-mm single drilling, ADMSCs were implanted into the necrotic zone. All patients underwent magnetic resonance imaging (MRI), single-photon emission computed tomography/computed tomography (SPECT/CT) at screening and 6 months, 12 months, and 24 months postoperatively. The primary outcome was the change in the size of necrotic area on MRI. Secondary outcomes were changes in clinical scores and radioisotope uptake on SPECT/CT. Conversion total hip arthroplasty (THA) was defined as the endpoint.ResultsPreoperatively, the necrotic lesion extent was 63.0% (38.4%–96.7%) of the femoral head. The mean Harris hip score was 89.2, the University of California at Los Angeles (UCLA) score was 5.6, and Western Ontario and McMaster Universities Arthritis index (WOMAC) was 79.4. Three patients underwent THA and 1 patient died in an accident. Finally, 11 patients (14 hips) were available for ≥ 2-year follow-up. At the last follow-up, no surgery-related complications occurred, and 14 of 17 hips (82%) were able to perform daily activities without THA requirement. There was no significant decrease in lesion size between any 2 intervals on MRI. However, widening of high signal intensity bands on T2-weighted images inside the necrotic lesion was observed in 9 of 14 hips (64%); 11 of 14 hips (79%) showed increased vascularity on SPECT/CT at 2 years postoperatively. No significant differences were observed between preoperative and 24-month mean Harris hip score (89.2 vs. 88.6), WOMAC (79.4 vs. 75.7), and UCLA score (5.6 vs. 6.2).ConclusionsOur outcomes suggest that culture-expanded ADMSC implantation is a viable option for ONFH treatment without adverse events.  相似文献   
34.
35.
BackgroundExcessive portal pressure after massive hepatectomy can cause hepatic sinusoidal injury and have deleterious impacts on hepatic functional recovery, contributing to developing post-hepatectomy liver failure. This study aimed to assess the effects of splanchnic vasoactive agents on hepatic functional recovery and regeneration while clarifying the underlying mechanism, using a 70% hepatectomy porcine model.MethodsEighteen pigs undergoing 70% hepatectomy were involved in this study and divided into three groups: control (n=6), terlipressin (n=6), and octreotide (n=6). Terlipressin (0.5 mg) and octreotide (0.2 mg) were administered 3 times a day for each group with the first dose starting just before surgery until the 7th postoperative day, at which time the surviving pigs were sacrificed. During the period, portal pressure, liver weight, biochemical analysis, histological injury score, and molecular markers were evaluated and compared between groups.ResultsThe 7-day survival rates in the octreotide, terlipressin, and control groups were 100%, 83.3%, and 66.7%, respectively. The portal pressures decreased in both terlipressin and octreotide groups than the control group at 30 minutes, 1 hour and 6 hours after hepatectomy. The amount of regeneration measured by liver weight to body weight ratio at the time of sacrifice in the terlipressin group was smaller than that in the control group (117% vs. 129%, P=0.03). Serum aspartate aminotransferase (AST) and total bilirubin levels at 1 and 6 hours after hepatectomy and prothrombin time/international normalized ratio (PT/INR) at 6 hours after hepatectomy were significantly improved in the terlipressin and octreotide groups compared to the control group. Serum endothelin-1 (ET-1) was significantly lower in the terlipressin group than that in the control group 6 hours after hepatectomy (P<0.01). The histological injury score in the control group was significantly higher than that in the terlipressin group on the 7th postoperative day (P<0.01).ConclusionsSplanchnic vasoactive agents, such as terlipressin and octreotide, could effectively decrease portal pressure and attenuate liver injury after massive hepatectomy.  相似文献   
36.
One case of arthritis complicating leukemia is described in which leukemic cells were identified in synovial fluid by light microscopy. Although arthritis is a well-known manifestation of leukemia with an incidence of 13.5%, the pathogenesis often is unclear, and the direct demonstration of leukemic cells in synovial fluid has been very uncommon. A 16 year-old male patient was admitted due to left elbow joint pain and swelling. Synovial fluid examination revealed blast cells and this finding has directed to a final diagnosis of acute lymphoblastic leukemia.  相似文献   
37.
Recombinant human epidermal growth factor (rhEGF), a polypeptide of 53 amino acid residues, is subject to degradation by numerous enzymes, especially proteases, when it is applied on the skin for the treatment of open wound. Amastatin, aprotinin, bestatin, EDTA, EGTA, gabexate, gentamicin, leupeptin, and TPCK were investigated for the possible protease inhibitors, which may use to protect rhEGF from degradation by the enzymes in the skin. Skin homogenates containing protease inhibitors and rhEGF were incubated at 37°C for 30 minutes. After the reaction was stopped with trifluoroacetic acid, the amount of rhEGF remaining in the sample was determined with an HPLC method. The percentages of rhEGF degraded, at the skin/PBS ratio of 0.25, in the mouse, rat, and human skin homogenate were 85%, 70%, and 46%, respectively. The degree of degradation of rhEGF in the cytosolic fraction was higher than that in the membrane fraction and these enzyme reactions were completed in 30 minutes. Bestatin, EGTA, and TPCK showed significant inhibitory effects on the degradation of rhEGF in the two fractions (p<0.05), while the other protease inhibitors had no significant inhibitory effects or, even resulted in deleterious effects. Therefore, the formulation containing one or several inhibitors among these effective inhibitors would be a promising topical preparation of rhEGF for the treatment of open wound.  相似文献   
38.
Our objective was to determine the incidence of complications in postoperative patients who were either normothermic or hypothermic. A recent, widely publicized paper concluded that the maintenance of normothermia could reduce the incidence of infectious complications and shorten hospitalization in patients undergoing colorectal surgery. However, some controversy arose regarding the methods of this paper. Patients were deliberately rendered hypothermic, were given more than 3.5 days of prophylactic antibiotics and were transfused significantly more units of blood. We reviewed the charts of 150 consecutive patients who underwent elective partial or subtotal colectomy with primary anastomosis. Among the key items analyzed were intraoperative and postoperative temperature, use of warming devices, duration of surgery, transfusions, interval to oral intake and bowel function, length of stay, complications, infections, and laboratory values. Hypothermia was defined as intraoperative temperature <95.5 degrees F. There were 101 normothermic patients and 49 hypothermic patients. Hypothermic patients had a mean age of 68.7 years versus 66.8 for the normothermic patients (P = 0.472). Comorbidities were similar in both groups. Warming devices were used in >90 per cent of the patients in both groups. The rates of postoperative infections and complications were similar in both groups. Postoperative lengths of stay were also not different. Despite finding that one-third of our patients were hypothermic during elective colon resection, hypothermia had no effect on outcome variables. In contrast to the previous study, the incidence of infectious complications was identical in our patients. Before ascribing postoperative complications and increased resource utilization as adverse effects of hypothermia, further studies are indicated.  相似文献   
39.
Neonatal porcine pancreas has considerable capacity for growth and differentiation, making it an attractive potential source of islet tissue for xenotransplantation. Pancreases from 1-3-day-old newborn pigs were digested with collagenase and cultured for 8 days. The resulting cellular aggregates are called porcine neonatal pancreatic cell clusters (NPCCs). The mean yield of NPCCs from a newborn pig was 28,200 +/- 1700 islet equivalents. Cytokeratin 7 (CK7) was used as a marker for the immunostaining of pancreatic duct cells. In neonatal pancreas, 18% of the insulin-positive cells co-stained for CK7, thus being protodifferentiated. NPCCs also contained protodifferentiated cells; insulin/PP and insulin/somatostatin co-stained cells were more common than insulin/glucagon cells. Between 1 and 8 days of culture, the DNA content of the NPCCs fell to 16% and the insulin content to 33% of the starting value, mainly due to the preferential loss of exocrine cells. Transplantation of 2000 or 4000 NPCCs into diabetic nude mice typically normalized glucose values in 10-20 weeks. Mice with successful grafts had lower fasting blood glucose levels than normal mice and accelerated glucose clearance after an i.p. glucose load. The starting NPCCs consisted of 17% insulin-staining cells, but the grafts of mice with reversed diabetes consisted of 94% beta cells, with some co-stained for CK7, indicating that the grafts still contained immature cells. The mass of insulin-producing cells rose from 0.22 +/- 0.08 mg 1 week after transplantation to 4.34 +/- 0.27 mg in mice sacrificed at 27-35 weeks. In summary, NPCCs contain mostly islet precursor cells, which when transplanted into nude mice undergo striking differentiation and beta cell expansion.  相似文献   
40.
Mouse-to-rat testicle transplantation   总被引:4,自引:0,他引:4  
This report details mouse-to-rat testicular transplantation with immediate revascularization. Donor preparation involved grafting a long segment of aorta and inferior vena cava (IVC) containing the testicular artery and vein. The graft aorta and IVC were anastomosed to the rat aorta and IVC, respectively. Vasovasostomy was completed and the scrotal epithelia were anastomosed to draw the graft toward the host scrotal sac. Twenty-nine of 53 transplants were determined to be viable. Histologically, 6- to 18-hr-old grafts displayed moderate to minimal polymorphonuclear neutrophil (PMN) infiltrates. Ischemia set in somewhere between 18-24 hr postoperatively. Beyond 24 hr the grafts displayed progressive infiltration of PMN and perivascular and intertubular lymphocytes, disorganization of the germinal epithelium, and cessation of spermatogenesis.  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