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   2140篇
  免费   83篇
  国内免费   30篇
耳鼻咽喉   3篇
儿科学   95篇
妇产科学   19篇
基础医学   418篇
口腔科学   77篇
临床医学   246篇
内科学   491篇
皮肤病学   112篇
神经病学   39篇
特种医学   266篇
外科学   163篇
综合类   48篇
预防医学   74篇
眼科学   25篇
药学   135篇
中国医学   1篇
肿瘤学   41篇
  2015年   24篇
  2014年   19篇
  2013年   74篇
  2012年   22篇
  2010年   43篇
  2009年   30篇
  2008年   22篇
  2007年   43篇
  2006年   44篇
  2005年   23篇
  2004年   18篇
  2003年   22篇
  2001年   29篇
  2000年   20篇
  1999年   33篇
  1998年   81篇
  1997年   94篇
  1996年   104篇
  1995年   70篇
  1994年   73篇
  1993年   76篇
  1992年   39篇
  1991年   36篇
  1990年   41篇
  1989年   66篇
  1988年   57篇
  1987年   48篇
  1986年   51篇
  1985年   38篇
  1984年   55篇
  1983年   27篇
  1982年   31篇
  1981年   37篇
  1980年   49篇
  1979年   23篇
  1978年   27篇
  1977年   35篇
  1976年   38篇
  1975年   36篇
  1972年   24篇
  1971年   21篇
  1970年   23篇
  1969年   18篇
  1965年   50篇
  1964年   50篇
  1963年   47篇
  1962年   41篇
  1961年   40篇
  1960年   65篇
  1959年   20篇
排序方式: 共有2253条查询结果,搜索用时 16 毫秒
71.
Thrombocytopoietic properties of oncostatin M   总被引:1,自引:2,他引:1  
Oncostatin M (OM) is a 28-kD glycoprotein that exhibits a panoply of biologic effects. Based on histologic observations of increased splenic megakaryocytes in nude mice implanted with an OM-secreting cell line, the thrombocytopoietic properties of OM in mice were investigated in culture and in vivo. Alone, OM did not induce megakaryocytic colony formation, but in combination with murine interleukin-3 (IL-3), OM markedly enhanced colony formation. The effects of OM on colony formation were similar to those of IL-6. OM alone augmented acetylcholinesterase in short-term marrow cultures. In normal mice, the administration of OM augmented platelet counts without increasing other circulating blood cell counts. The increment in counts exceeded that observed with IL-6. The kinetics of the OM response suggested that maximal increases in platelets occurred 3 days after the cessation of OM administration, irrespective of the duration of administration. In irradiated mice, OM administration accelerated platelet recovery and prevented the decrease in red blood cells observed in irradiated control animals. The data show that OM behaves as a megakaryocytic maturation factor in vitro and augments platelet production in vivo. Based on these animal data, OM may have potential clinical utility as a thrombocytopoietic agent.  相似文献   
72.
Interventions in saphenous vein grafts present some of the most challenging problems in preventing acute complications and limiting restenosis. Available options include repeat bypass surgery, balloon angioplasty, directional atherectomy, transluminal extraction atherectomy, rotational atherectomy, laser angioplasty, and stenting. Stenting appears to provide the best acute and long-term results. Debulking with directional atherectomy prior to stenting may be helpful but its role is unproven. With any device, it is essential to attain the lowest possible residual stenosis with the least amount of manipulation. Complications with vein graft interventions are most commonly related to distal embolization, which occurs most frequently in older vein grafts with diffuse disease, large plaque volume or thrombus, or those with total occlusion. Use of thrombolytics, glycoprotein Ilb/IIIa receptor inhibitors, and thrombectomy devices may be helpful when thrombus is present. Calcium channel blockers may be beneficial when embolization of plaque debris results in slow flow or no-flow during interventions.  相似文献   
73.
74.
In mice and in dogs, the usefulness of infusions of marrow in reducing thetoxicity of thio-TEPA is limited to a very narrow range of dose of drug inwhich prompt restoration of hematopoiesis seems critical to survival. Belowthis range, control animals recover spontaneously; above this range, damageto other organ systems precludes survival.

Submitted on August 21, 1962 Accepted on October 29, 1962  相似文献   
75.
76.
Ball  ED; Mills  LE; Coughlin  CT; Beck  JR; Cornwell  GG d 《Blood》1986,68(6):1311-1315
Second or third chemotherapy-induced remissions in acute myelogenous leukemia (AML) are limited by early relapse of the leukemia. We developed monoclonal antibodies (MoAbs) that are cytotoxic to myeloid leukemia cells to treat bone marrow from these patients ex vivo for autologous transplantation. In this pilot study, bone marrow was harvested from ten patients with AML in remission, treated with one or two complement-fixing MoAbs, PM-81 and AML-2-23, which react with myeloid differentiation antigens, incubated with rabbit complement, and cryopreserved. These MoAbs were chosen because they have broad reactivity with AML cells but not with pluripotent progenitor cells. At the time of transplant, 6 patients were in second complete remission, 1 each was in third complete or partial remission, and 2 were in early first relapse. The patients were treated with cyclophosphamide (60 mg/kg a day for 2 days) and total body irradiation (200 cGy twice a day for 3 days) and given infusions of MoAb-treated bone marrow. Full bone marrow reconstitution was observed in eight patients; two patients did not recover platelets. Seven of the ten patients are surviving and disease-free at 21.0, 15.0, 13.0, 10.0, 6.0, 3.0, and 2.0 months posttransplant. Treating bone marrow with MoAbs to myeloid differentiation antigens does not interfere with pluripotential stem cell engraftment. Longer follow-up and a controlled study are necessary to prove that the apparent efficacy of this therapeutic approach in some patients is attributable to MoAb-mediated killing of leukemia cells.  相似文献   
77.
Using accepted diagnostic criteria we have selected, for study, 160 patients with Crohn's disease involving the colon. There is a remarkable discrepancy between the clinical diagnosis prior to or at the time of initial admission to this hospital and the diagnosis following definitive investigation and observation of the progression of disease.
The peak age incidence occurred in the second decode The colitis group showed a greater percentage of patients over 30 years of age. Although histopathology was not obtained in all patients, there appeared to be sparing of the ascending colon in a small percentage (9%) of patients with ileocolitis.
Comparison of the clinical features of granulomatous disease limited to the colon and granulomatous ileocolitis shows a significantly greater incidence of extraintestinal symptoms and overt bleeding in the former. Nausea, vomiting, subacute obstruction, abdominal mass and internal fistulas were substantially more common in ileocolitis but the difference was not statistically significant. In this series retroperitoneal abscess did not occur in patients with disease localized to the colon. In the 10 patients with ileocolitis who developed an abscess, however, the site of fistula was the colon in four patients. In one of these, the abscess was left-sided.  相似文献   
78.

Background

Dietary oleic acid may prevent pancreatic ductal adenocarcinoma (PDA) by reducing hyperinsulinaemia which can otherwise promote DNA damage and tumour growth. Results from previous epidemiological studies investigating oleic acid are inconsistent. This study aims to clarify the relationship between dietary oleic acid intake and the risk of developing PDA using nutritional information from food diaries plus published serum biomarker data from HbA1c.

Methods

23,658 participants, aged 40–74 years, were recruited into EPIC-Norfolk and completed 7-day food diaries which recorded; foods, brands and portion sizes to calculate nutrient intakes. Serum HbA1c was measured at recruitment in 11,147 participants (48.7% of cohort). Hazard ratios (HRs) for quintiles of dietary oleic acid intake and serum HbA1c were estimated using Cox regression. Additional analyses were made according to whether body mass index (BMI) was greater or less than 25?kg/m2 as this influences hyperinsulinaemia.

Results

88 participants (55% women) developed PDA after a mean follow-up of 8.4 years (SD?=?3.9) (mean age at diagnosis?=?72.6 years, SD?=?8.8). A decreased risk of PDA was associated with increased dietary oleic acid intake (highest vs lowest quintile, HR?=?0.29, 95% CI?=?0.10–0.81, P trend across quintiles?=?0.011), with statistical significance maintained when BMI>25?kg/m2 but not if BMI<25?kg/m2. An elevated serum HbA1c was associated with increased risk of disease (highest vs lowest quintiles, HR?=?6.32, 95% CI?=?1.38–28.89, P for trend?=?0.004).

Conclusions

The data supports a protective role of oleic acid against development of PDA in those with higher BMIs possibly through influencing hyperinsulinaemia. Oleic acid intake should be accurately measured in future aetiological studies.  相似文献   
79.
Retroperitoneal lumbocrural abscess occurred in 12 patients of 231 with Crohn's colitis or ileocolitis. Although all patients with this complication fell within the group of 175 ileocolitis patients, at least four originated in fistulous tracts of the colon. Eleven of the 12 abscesses developed spontaneously as the first major complication of the disease. The prominent clinical features included pain radiating down the thigh, hip joint flexion, difficulty in walking, hydronephrosis and hydroureter. Internal and external fistulas were significantly more common in the abscess group of 12 patients than in the 219 patients without retroperitoneal abscess. Radiological evidence of granulomatous disease was found in all patients; fistulous tract formation was characteristic and the development of extraperitoneal gas bubbles, in four patients, pathognomonic of abscess with gast-forming organisms. In the presence of established retroperitoneal abscess, the surgical sequence suggested is drainage synchronous with, or followed by diversion and ultimately definitive resection. Resection with anastomosis should not be carried out in the presence of an acute inflammatory process with frank abscess or free pus communicating with the peritoneal cavity. The spontaneous development of retroperitoneal abscess is a serious development in the natural history of Crohn's (ileo) colitis. It frequently heralds the first of a series of operative procedures to deal with the abscess. It sequels are enterocutaneous fistulas and further extension of the disease process.  相似文献   
80.
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