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   576篇
  免费   40篇
  国内免费   22篇
儿科学   37篇
妇产科学   3篇
基础医学   57篇
口腔科学   8篇
临床医学   75篇
内科学   109篇
皮肤病学   4篇
神经病学   7篇
特种医学   176篇
外科学   41篇
综合类   15篇
预防医学   44篇
眼科学   6篇
药学   41篇
肿瘤学   15篇
  2020年   3篇
  2018年   3篇
  2015年   6篇
  2014年   10篇
  2013年   15篇
  2012年   5篇
  2011年   4篇
  2010年   11篇
  2009年   9篇
  2007年   14篇
  2006年   4篇
  2005年   11篇
  2004年   3篇
  2003年   3篇
  2002年   2篇
  2001年   9篇
  2000年   5篇
  1999年   8篇
  1998年   32篇
  1997年   29篇
  1996年   40篇
  1995年   23篇
  1994年   19篇
  1993年   28篇
  1992年   9篇
  1991年   6篇
  1990年   15篇
  1989年   29篇
  1988年   26篇
  1987年   32篇
  1986年   17篇
  1985年   27篇
  1984年   14篇
  1983年   15篇
  1982年   23篇
  1981年   15篇
  1980年   13篇
  1979年   6篇
  1978年   3篇
  1977年   9篇
  1976年   20篇
  1975年   7篇
  1973年   5篇
  1972年   3篇
  1971年   6篇
  1969年   10篇
  1968年   7篇
  1967年   3篇
  1966年   4篇
  1957年   2篇
排序方式: 共有638条查询结果,搜索用时 31 毫秒
51.
Purpose: To retrospectively examine the optic disc photographs of a glaucoma population for optic disc haemorrhages, vascular occlusions and vascular abnormalities. Methods: The optic disc photographs of 906 eyes of glaucoma and suspect glaucoma patients were examined. Optic disc photographs were taken annually, where possible, with the follow-up period varying between 1 and 14 years duration (mean, 2.89). Glaucoma patients are regularly reviewed every 4–6 months and glaucoma suspects every 1–2 years, depending on the ophthalmologist. Low-tension glaucoma patients were reviewed more frequently (mean, every 2.6 months). The results of the findings were compared to a control group of 39 subjects with a mean follow-up period of 7 years, using Fisher's exact test. Results: It was found that during the period under review, 7.4% (n= 67) of eyes had optic disc haemorrhages. The highest frequency of optic disc haemorrhages (37.5%) was found in the low tension glaucoma group (P= 0.0001) followed by 11.4% of primary open-angle glaucoma eyes (P= 0.03). In the normal group there were three eyes with optic disc haemorrhages and one with a disc collateral, which constitutes 5.1% vascular changes in this sub-group. Of the study eyes 2.8% had central retinal vein occlusions, 1.3% branch vein occlusion, 1.2% disc vessel abnormalities (loops) and 1.1% disc collaterals. Discrete nerve fibre layer haemorrhages and microaneurysms were found in 0.8% and 1.8% of eyes, respectively. Conclusions: A total of 16.8% of the eyes observed in this study had either disc haemorrhages or vascular changes. The underlying trend of vascular and haemorrhagic changes in glaucoma are demonstrated in this sample, which is in general agreement with previous studies. The high percentage of optic disc haemorrhages in low tension glaucoma is highlighted. The presence of microaneurysms and nerve fibre layer haemorrhages is interesting but of unknown significance.  相似文献   
52.
In chronic inflammatory diseases, cytokines stimulate the hypothalamus pituitary adrenal axis and the hypothalamus autonomic nervous system (HANS) axis. The present study was performed to find autonomic nervous function parameters in patients with systemic lupus erythematosus (SLE) which are suitable to demonstrate the activation of the HANS axis during systemic inflammation. Thirty-four patients with SLE (age 35.3 +/- 1.9 yr) were investigated by seven standardized autonomic nervous function tests. The SLEDAI and laboratory parameters of systemic inflammation were assessed by standard techniques. Pupillary latency time hyperreflexia was found in 29.4%, whereas maximal pupillary area was hyperresponsive in only 2.9%. A total of 12% had overall cardiovascular autonomic nervous hyperreflexia. Patients with latency time hyperreflexia had more severe systemic inflammation [erythrocyte sedimentation rate (ESR): P < 0.001; C-reactive protein (CRP): P = 0.0094; fibrinogen: P < 0.001; albumin: P = 0.003; antinuclear antibodies: P = 0.020]. The longitudinal study of 13 patients during 4 yr demonstrated a parallel increase and decrease in latency time percentile and ESR. SLE patients with increased systemic inflammation had an activated HANS axis which can be measured by a parasympathetic pupillary reflex test.   相似文献   
53.
Stabler  SP; Lindenbaum  J; Savage  DG; Allen  RH 《Blood》1993,81(12):3404-3413
Homocysteine can be methylated to form methionine by the cobalamin- (Cbl) and folate-dependent enzyme, methionine synthase; serum levels of total homocysteine are elevated in greater than 95% of patients with either Cbl or folate deficiency. Homocysteine can also condense with serine to form cystathionine in a pyridoxal phosphate-dependent reaction catalyzed by cystathionine beta-synthase. Cystathionine is subsequently cleaved to cysteine and alpha-ketobutyrate by the pyridoxal phosphate-dependent enzyme gamma-cystathionase. To assess levels of cystathionine in Cbl and folate deficiency, we developed a new capillary gas chromatographic-mass spectrometric assay and measured cystathionine in the serum of normal subjects and patients with clinically confirmed deficiencies of these vitamins. The normal range for serum cystathionine was 65 to 301 nmol/L (median = 126 nmol/L) for 50 normal blood donors. In 30 patients with clinically confirmed Cbl deficiency, values for cystathionine ranged from 208 nmol/L to 2,920 nmol/L (median = 816 nmol/L) and 26 (87%) had levels above the normal range. In 20 patients with clinically confirmed folate deficiency, cystathionine concentrations ranged from 138 nmol/L to 4,150 nmol/L (median = 1,560 nmol/L) and 19 (95%) had values above the normal range. Five homozygotes for cystathionine beta-synthase deficiency had high values for serum-total homocysteine and low or low-normal values for serum cystathionine that ranged from 30 nmol/L to 114 nmol/L even though they were on treatment with pyridoxine and had partially responded. One patient with a defect in the synthesis of 5-CH3- tetrahydrofolate and five patients with defects in the synthesis of CH3- Cbl had high values for serum-total homocysteine and high values for cystathionine that ranged from 311 nmol/L to 1,500 nmol/L even though they were on treatment with folic acid and Cbl, respectively, and had partially responded. We conclude that levels of cystathionine are evaluated in the serum of most patients with Cbl and folate deficiency and that they are useful in the differential diagnosis of an elevated serum-total homocysteine level.  相似文献   
54.
Composites are increasing in popularity as restorative materials. This growing role indicates the necessity of studies on their clinical outcome. In this study, clinical studies published on the performance of posterior composite restorations were included except those of less than a 24‐month assessment period. Results of non‐vital, anterior or primary teeth and cervical single‐surface restorations were also excluded. Records about composite type, number of final recall restorations, failure/survival rate, assessment period and failure reasons were analysed for each decade. Overall survival/failure rates for studies in 1995–2005 were 89.41%/10.59% and for 2006–2016 were 86.87%/13.13%, respectively. In 1995–2005, the reasons for failure were secondary caries (29.47%) and composite fracture (28.84%) with low tooth fracture (3.45%) compared with reasons of failure in 2006–2016, which were secondary caries (25.68%), composite fracture (39.07%), and tooth fracture (23.76%). An increase in incidence of composite fracture, tooth fracture and need for endodontic treatment as failure reasons was noted in the latter decade in addition to a decrease in secondary caries, postoperative sensitivity, unsatisfactory marginal adaptation and wear. The overall rates of failure showed little difference, but the causes showed a notable change. This is believed to be a reflection of increased use of composites for larger restorations and possibly changes of material characteristics.  相似文献   
55.
Twenty-six patients with progressive Hodgkin's disease after conventional chemotherapy received intensive chemoradiotherapy and autologous bone marrow transplantation (ABMT); 19 also received additional involved-field radiotherapy. Twenty-one patients [81%, 95% confidence intervals (CI) 61% to 94%] attained complete (n = 18) or partial responses. Ten patients (38%, 95% CI 20% to 59%) are disease- free a median of 4.5 years later (range 3.5 to 7.0 years), including seven patients with continuous complete responses. The likelihood of overall response was not significantly influenced by any clinical or treatment variable examined. However, there was a trend favoring patients with higher Karnofsky scores, and higher scores were associated with attainment of complete responses (P = .06 and P = .02, respectively, Mann-Whitney U test). Both higher Karnofsky scores and shorter durations of disease before transplantation were associated with improved survival in a stepwise Cox multivariate analysis. The chief cause of failure was progression at sites previously involved with Hodgkin's disease. No patient relapsed in the marrow, and two of three patients with a history of marrow involvement with Hodgkin's disease achieved durable complete responses after transplantation. These data suggest that inadequate pretransplant conditioning, and not the reinoculation of occult tumor cells in the autologous marrow, caused most relapses. Fatal treatment-related toxicity occurred in six patients. Three patients died of idiopathic interstitial pneumonitis; each had previously received local mediastinal irradiation before intensive chemoradiotherapy. Intensive chemoradiotherapy and ABMT produces durable responses in some patients with Hodgkin's disease incurable with conventional therapy. Use of such therapies at the first sign of failure with conventional chemotherapy and development of more effective conditioning regimens should further improve results.  相似文献   
56.
High-dose (HD) cytosine arabinoside (ARA-C) is more effective treatment than conventional-dose ARA-C regimens for patients with relapsed acute nonlymphocytic leukemia (ANLL). We report here that HD ARA-C given during the first remission of ANLL has resulted in long remission durations and a high proportion of patients who survive more than three years free of disease. From August 1979 to September 1983, 36 adult patients with ANLL in first remission received one to three courses of HD ARA-C (3 g/m2 by one-hour infusion every 12 hours for 12 doses on days 1 through 6) alone or with daunorubicin (30 mg/m2 for two or three doses on days 7 through 9). Three patients died of sepsis or hemorrhage during consolidation, and 14 patients have relapsed from five to 48 months after diagnosis. The remaining 19 patients are in continued complete remission (CCR) from 11 to 62 months. Denoting all deaths in remission as relapse, the actuarial probability of CCR is 42% at 62 months, with an apparent plateau in the survival curve. Of the first 22 patients treated, ten remain in CCR from 37 to 62 months with no therapy for at least three years. Due to its heightened anti-leukemic activity, HD ARA-C allows brief but effective consolidation of ANLL in first remission, with long-term disease-free survival comparable to other approaches.  相似文献   
57.
我非常高兴向大家推荐这份发展中国家幽门螺杆菌(H.priori)临床指南。该指南的编译是由数位在该领域具有丰富临床经验的世界知名专家共同完成的。  相似文献   
58.
Kickler  TS; Herman  JH; Furihata  K; Kunicki  TJ; Aster  RH 《Blood》1988,71(4):894-898
Baka is a platelet alloantigen whose putative allele, Bakb, has not been identified previously. By using a serum, "Har," obtained from a patient with posttransfusion purpura, we describe the platelet alloantigen Bakb. The Har serum reacted with an NP-40-extractable platelet membrane protein of 142 kd with mobility similar to platelet glycoprotein IIb alpha. We found that the antigen recognized by the Har serum is inherited in an autosomal dominant mode with an apparent gene frequency of .39. Chi-square analysis of observed and expected phenotype frequencies indicated that serum Har recognizes Bakb, the anticipated allele of Baka. Our findings provide new evidence for polymorphism of glycoprotein IIb and for the association of posttransfusion purpura with alloimmunization to determinants on this glycoprotein.  相似文献   
59.
In order to study the fat-soluble vitamin concentration of patients with chronic alcohol-induced pancreatitis (CAIP) we measured vitamins A and E, total lipids, and retinol-binding protein (RBP) in the plasma of 44 patients with CAIP and 83 controls (44 healthy controls; 39 Crohn's disease patients). Mean plasma vitamin E and vitamin E/total lipid ratio were significantly lower in CAIP when compared with either control or Crohn's disease groups. A low vitamin E/total lipid ratio was found in 75% of CAIP patients (91% with steatorrhea) and a ratio less than 1.0 was virtually 100% predictive of steatorrhea. The mean plasma vitamin A level for the CAIP group was significantly lower (overall 16%, 38% with steatorrhea) than in controls. Patients with CAIP show subnormal plasma levels vitamin E more often as compared to vitamin A. Further, the plasma vitamin E/total lipids ratio may be a sensitive and practical means in the detection and follow-up of steatorrhea in these patients.This work was accepted for oral presentation at the XXII Meeting of the European Pancreatic Club, September 16–18, 1991, Lund, Sweden.  相似文献   
60.
The clinical features found in 14 children with toxocara ELISA titres of greater than or equal to 0.7 were compared with those found in 34 toxocara negative children. Blood eosinophils were elevated in 7 of the 14 patients and the highest eosinophilia was 14%. There was a highly significant association between hepatomegaly, cough, sleep disturbance and a raised titre (p less than 0.01). Behaviour disturbance, abdominal pain and headache were also significantly associated with a raised titre (p less than 0.05). The combination of abdominal pain, headache and cough was even more significantly associated with a high titre (p less than 0.0005) than were individual clinical features. It is suggested that in addition to the two well recognised clinical conditions of visceral larva migrans and ocular toxocariasis the clinical entity of covert toxocariasis should receive recognition. Eosinophilia may or may not be present in this condition.  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