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   3580篇
  免费   312篇
  国内免费   31篇
耳鼻咽喉   33篇
儿科学   198篇
妇产科学   76篇
基础医学   421篇
口腔科学   106篇
临床医学   438篇
内科学   626篇
皮肤病学   92篇
神经病学   187篇
特种医学   381篇
外科学   477篇
综合类   132篇
一般理论   2篇
预防医学   278篇
眼科学   47篇
药学   197篇
中国医学   3篇
肿瘤学   229篇
  2023年   21篇
  2022年   31篇
  2021年   47篇
  2020年   31篇
  2019年   43篇
  2018年   76篇
  2017年   80篇
  2016年   64篇
  2015年   93篇
  2014年   134篇
  2013年   323篇
  2012年   142篇
  2011年   143篇
  2010年   123篇
  2009年   136篇
  2008年   102篇
  2007年   134篇
  2006年   136篇
  2005年   106篇
  2004年   96篇
  2003年   94篇
  2002年   78篇
  2001年   75篇
  2000年   94篇
  1999年   71篇
  1998年   116篇
  1997年   105篇
  1996年   122篇
  1995年   77篇
  1994年   93篇
  1993年   54篇
  1992年   56篇
  1991年   66篇
  1990年   54篇
  1989年   71篇
  1988年   56篇
  1987年   56篇
  1986年   74篇
  1985年   85篇
  1984年   29篇
  1983年   32篇
  1982年   34篇
  1981年   24篇
  1980年   24篇
  1979年   26篇
  1978年   16篇
  1977年   13篇
  1976年   20篇
  1975年   16篇
  1974年   16篇
排序方式: 共有3923条查询结果,搜索用时 6 毫秒
41.
OBJECTIVE: Colonic infarction is a recognized complication of abdominal aortic aneurysm (AAA) surgery. The clinical difficulty in establishing the diagnosis combined with the patient's poor physiological status is usually associated with a fatal outcome. We assessed our experience with this problem to identify a possible risk factor profile for these patients. METHOD: Patients records were identified from the operative logs, intensive care unit, Hospital Inpatient Enquiry system and vascular unit databases over a 6-year period. RESULTS: A total of 405 patients underwent AAA repair during this period; 140 as emergency ruptures. Nine patients were identified from the databases with known colonic infarction (2.2%). One was a woman. The mean age was 70 years. Seven patients had emergency ruptures (5%). Twenty independent risk factors were analysed using univariate and multivariate logistic regression models. Significant risk factors identified by using a multivariate analysis included the nature of the presenting patient, preoperative hypotension, prolonged cross-clamp time, intra-operative ischaemia and postoperative acidosis. Confirmatory diagnosis was made by colonoscopy in eight patients. One patient survived following the salvage surgery. The mean duration of survival was 10.5 days. The overall mortality was 89% of patients. CONCLUSION: In our unit infrarenal AAA repair has a 2.2% rate of colonic infarction. A definitive diagnosis is best made by colonoscopy. A risk factor profile for the development of colonic infarction may be constructed on the basis of specific clinical parameters. Earlier intervention on the basis of this profile may ultimately reduce the current excessive mortality.  相似文献   
42.
BACKGROUND: Talactoferrin alfa, a recombinant form of human lactoferrin, is a novel immunomodulatory protein with demonstrated ulcer healing properties in animal models. METHODS: A phase 1/2 clinical study was conducted at 7 clinical sites to determine if talactoferrin can improve wound healing in diabetic patients with foot ulceration. Fifty-five patients with diabetic neuropathic foot ulcers participated in this 2-phase study. In phase 1, groups of 3 patients each received open-label 1%, 2.5%, or 8.5% talactoferrin gel twice daily, in a sequential design, to their ulcer for 30 days. No drug-related adverse events were found at any dose level. Phase 2 was a randomized, placebo-controlled, single-blind study of 2.5% and 8.5% gels, with patients equally divided between the 3 groups. In combination with good wound care, treatment was administered topically twice daily to the ulcers for 12 weeks. The primary endpoint was the incidence of > or = 75% healing (relative to baseline size). RESULTS: The study, which in phase 2 was powered to detect a difference between the placebo and combined talactoferrin arms with P < .1, met the primary objective. The groups receiving the 2.5% (n = 15) and 8.5% (n = 15) gels had twice the incidence of > or = 75% reduction in ulcer size compared with the placebo group (n = 16): 47%, 53%, and 25%, respectively. On an intent-to-treat basis, the combination of the 2 active groups when compared with the placebo group showed a strong trend toward statistical significance (P = .09). There were no talactoferrin-related adverse events or laboratory abnormalities. CONCLUSIONS: Topical talactoferrin appears to be safe and well tolerated and improves healing of diabetic neuropathic ulcers.  相似文献   
43.
The clinical, CT, and magnetic resonance features of two cases of hypothalamic/optic chiasm involvement with Langerhans cell histiocytosis are presented. In both cases, the mass was iso- to hyperdense on noncontrast CT with uniform postcontrast enhancement, whereas with magnetic resonance (one case) the mass remained isointense to brain on both long and short repetition time sequences. The pathophysiology of hypothalamic pituitary dysfunction is briefly reviewed.  相似文献   
44.
45.
46.
Heterogeneity of B cell involvement in acute nonlymphocytic leukemia   总被引:2,自引:0,他引:2  
In order to study the pattern of B cell involvement in acute nonlymphocytic leukemia (ANLL), multiple B lymphoid cell lines were established by Epstein-Barr virus transformation of peripheral blood mononuclear cells from two patients with the disease who were heterozygous for the X chromosome-linked glucose-6-phosphate dehydrogenase (G6PD). In one patient, the progenitor cells involved by the leukemia exhibited multipotent differentiative expression, whereas in the other patient the cells showed differentiative expression restricted to the granulocytic pathway. In the patient whose abnormal clone showed multipotent expression, the ratio of B-A G6PD in B lymphoid cell lines was skewed in the direction of type B (the enzyme characteristic of the leukemia clone) and significantly different from the 1:1 ratio expected. It is, therefore, likely that the neoplastic event occurred in a stem cell common to the lymphoid series as well as to the myeloid series. In contrast, evidence for B cell involvement was not detected in the patient whose ANLL progenitor cells exhibited restricted differentiative expression. These findings underscore the heterogeneity of ANLL. Clinically and morphologically similar malignancies in these two patients originated in progenitors with different patterns of stem cell differentiative expression. This difference may reflect differences in cause and pathogenesis.  相似文献   
47.
Charbord  P; Gown  AM; Keating  A; Singer  JW 《Blood》1985,66(5):1138-1142
The CGA-7, a monoclonal antibody that reacts with smooth muscle cell actin but not with endothelial cell or fibroblast actin, and HHF, a monoclonal antibody that reacts with smooth muscle, skeletal muscle, and cardiac muscle actin, both recognize microfilaments present within adherent cells from actively hematopoietic human long-term marrow cultures. Macrophages, monocytes, and cultured marrow fibroblasts do not react with either antibody. These data suggest that the anti-actin antibodies may serve as useful markers for in vitro microenvironmental cells and lend support to the hypothesis that stromal cells from long- term marrow cultures are different from marrow fibroblasts and may constitute a unique cell lineage.  相似文献   
48.
The influence of multiple clinical, angiographic and technical variables on the outcome of percutaneous transluminal coronary angioplasty was evaluated in a group of 76 consecutive patients with total coronary artery occlusion. Angioplasty was performed successfully in 53% of these patients. The likelihood of successful angioplasty was favorably influenced by: 1) a history of prior myocardial infarction in the distribution of the occluded arterial segment (p = 0.03); 2) an estimated maximal duration of arterial occlusion of less than 20 weeks (p less than 0.001); and 3) a length of nonvisualized arterial segment distal to the point of occlusion of less than 1.5 cm (p = 0.03). The outcome of coronary angioplasty was not significantly influenced by the vessel involved, the location of the occlusion within an involved vessel, the morphology of the occlusion (tapered versus abrupt) or the age and sex of the patient. There were no deaths and no vascular perforations. Four patients had recurrent coronary occlusion within 24 hours of the procedure; in three of these, recurrent occlusion was successfully treated with reangioplasty and in one, emergent surgical revascularization was performed. Embolic occlusion of an arterial branch distal to the point of total coronary occlusion occurred in 4 of the 40 successfully recanalized arteries. Seventy-five percent of patients having successful recanalization of an occluded coronary artery were free of the anginal symptoms that had prompted performance of the procedure at a mean follow-up period of 7.3 months. Thus, angioplasty of a total coronary artery occlusion can be performed safely and effectively, particularly in patients with a history of prior myocardial infarction, a brief estimated duration of coronary occlusion and a short nonvisualized occluded arterial segment.  相似文献   
49.
Intravenous urokinase in acute myocardial infarction   总被引:4,自引:0,他引:4  
To achieve reperfusion early, an intravenous bolus of 2 million units of urokinase was administered in 50 patients with transmural acute myocardial infarction (AMI) 1.8 +/- 2.5 hours after the onset of symptoms. Coronary angiography performed 1.1 +/- 0.6 hours after urokinase therapy revealed patent coronary arteries in 30 patients (60%), with no significant difference between those with anterior and those with inferior AMI. Reocclusion occurred in only 1 of 24 patients restudied. Failure to achieve reperfusion was not related to the degree of systemic fibrinolytic activity, which was equally high in patients who did and those who did not achieve reperfusion, as evident from serially obtained fibrinogen measurements (77 +/- 52 vs 84 +/- 24 mg/dl, difference not significant). Plasmin activity, measured serially from 15 minutes to 24 hours after urokinase in 7 patients, was maximal at 15 minutes and undetectable after 3 hours. Wall motion at the infarct site measured from contrast ventriculograms was significantly better at follow-up only in patients in whom reperfusion was achieved and who received urokinase within 2 hours after the onset of symptoms as compared with patients in whom reperfusion was not achieved (-1.2 +/- 1.4 vs -2.4 +/- 0.9 standard deviations from normal, p less than 0.05). Peak serum creatine kinase level was significantly lower in patients in whom reperfusion was achieved than in those in whom it was not or those who had rethrombosis (802 +/- 763 vs 1,973 +/- 1,071 U/liter, p less than 0.005).(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
50.
OBJECT: Lung carcinoma is the leading cause of death from cancer. More than 25% of those patients with lung cancer develop a brain metastasis at some time during the course of their disease. Corticosteroid therapy, radiotherapy, and resection have been the mainstays of treatment. Nonetheless, the median survival for patients with lung carcinoma metastasis is approximately 3 to 6 months. The authors examine the efficacy of gamma knife radiosurgery (GKS) for treating non-small cell lung carcinoma (NSCLC) metastases to the brain and evaluate factors affecting long-term patient survival. METHODS: A retrospective review of 273 patients who had undergone GKS to treat a total of 627 NSCLC metastases was performed. Clinical and neuroimaging data encompassing a 14-year treatment interval were collected. Univariate and multivariate analyses were performed to determine significant prognostic factors influencing patient survival. The overall median patient survival time was 15 months (range 1-116 months) from the diagnosis of brain metastases. The median survival was 10 months from GKS treatment in those patients with adenocarcinoma and 7 months for those with other histological tumor types. In patients with no active extracranial disease at the time of GKS, the median survival time was 16 months. In multivariate analyses, factors significantly affecting survival included: 1) female sex (p = 0.014); 2) preoperative Karnofsky Performance Scale score (p < 0.0001); 3) adenocarcinoma histological subtype (p = 0.0028); 4) active systemic disease (p = 0.0001); and 5) time from lung cancer diagnosis to the development of brain metastasis (p = 0.0074). Prior tumor resection or whole-brain radiation therapy did not correlate with extended patient survival time. Postradiosurgical imaging of brain metastases revealed that 60% decreased, 24% remained stable, and 16% eventually increased in size. Factors affecting local tumor control included tumor volume (p = 0.042) and treatment isodose (p = 0.015). Fourteen patients (5.1%) later underwent craniotomy and tumor resection for tumor refractory to GKS or a new symptomatic metastasis. CONCLUSIONS: Gamma knife surgery for NSCLC metastases affords effective local tumor control in approximately 84% of patients. Early detection of brain metastases, aggressive treatment of systemic disease, and a therapeutic strategy including GKS can afford patients an extended survival time.  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