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   474篇
  免费   27篇
  国内免费   41篇
耳鼻咽喉   8篇
儿科学   20篇
妇产科学   1篇
基础医学   77篇
口腔科学   18篇
临床医学   48篇
内科学   178篇
皮肤病学   3篇
神经病学   16篇
特种医学   55篇
外科学   24篇
综合类   16篇
预防医学   21篇
眼科学   5篇
药学   34篇
中国医学   1篇
肿瘤学   17篇
  2023年   1篇
  2022年   3篇
  2021年   12篇
  2020年   6篇
  2019年   6篇
  2018年   4篇
  2017年   7篇
  2016年   6篇
  2015年   19篇
  2014年   15篇
  2013年   23篇
  2012年   15篇
  2011年   15篇
  2010年   21篇
  2009年   18篇
  2008年   18篇
  2007年   41篇
  2006年   24篇
  2005年   37篇
  2004年   14篇
  2003年   14篇
  2002年   19篇
  2001年   10篇
  2000年   10篇
  1999年   9篇
  1998年   15篇
  1997年   29篇
  1996年   20篇
  1995年   7篇
  1994年   10篇
  1993年   8篇
  1992年   3篇
  1991年   5篇
  1990年   2篇
  1989年   10篇
  1988年   7篇
  1987年   9篇
  1986年   7篇
  1985年   3篇
  1984年   7篇
  1983年   4篇
  1982年   4篇
  1981年   8篇
  1980年   6篇
  1979年   1篇
  1977年   1篇
  1976年   7篇
  1975年   2篇
排序方式: 共有542条查询结果,搜索用时 0 毫秒
61.
A 36 year-old infertile female developed a stage IV (FIGO) ovarian carcinoma consisting of a poorly differentiated Sertoli-Leydig cell tumour after receiving one course of ovulation induction with follicle stimulating hormone (FSH), human menopausal gonadotrophin (HMG) and human chorionic gonadotrophin (HCG) followed by gonadotrophin-releasing hormone analogue (GnRHa). The patient died of liver metastasis and hepatic failure 4 1/2 months after first diagnosis, despite aggressive treatment consisting of debulking surgery and aggressive adjuvant chemotherapy.   相似文献   
62.
The evaluation of a new computer program for analysis and interpretation of pediatric Frank vectorcardiograms is reported. The program includes extensive age- and sex-dependent criteria based on tables of limits for numerous vectorcardiographic parameters. In 728 catheterized patients, the diagnostic performance for type A statements was tested against independent and objective evidence obtained from hemodynamic and angiographic data. The overall diagnostic accuracy ranged from 75 to 89% without difference between children < 2 years of age and those >- 2 years of age. Sensitivities and specificities of the various diagnoses did not differ much between the 2 age groups. In the younger children, the accuracy of a positive diagnosis of left ventricular hypertrophy, right ventricular hypertrophy, and biventricular hypertrophy was 20, 15, and 32% higher, respectively, than in the older children. The accuracy of the diagnosis “normal” was 28% lower in the younger children. These differences were explained by the higher proportion of pathologic findings in the younger children: 93% versus 74% in the older children.Given the strict methods of the evaluation, the diagnostic accuracy of this pediatric program was considered clinically satisfactory. Program performance appears to be dependent not on patient age but on prevalence of abnormalities in the population analyzed. Further improvement can be expected by making the criteria more adaptable to the composition of the population.  相似文献   
63.
We investigated the efficacy of 2-chlorodeoxyadenosine (2-CdA) therapy in patients with mycosis fungoides (MF) and the Sezary syndrome (SS). Between February 1991 and November 1993, 21 patients with relapsed or refractory MF/SS were treated with 2-CdA. 2-CdA was administered by continuous intravenous infusion at a dose of 0.1 mg/kg/d for 7 days initially (13 patients), but was subsequently reduced to 5 days (nine patients) due to hematologic toxicity. All patients had failed to respond to at least one prior treatment for MF/SS (median number of total prior therapies, five; median number of systemic prior therapies, three) and had an Eastern Cooperative Oncology Group performance status of two or better. Cycles were administered at 28-day intervals. Assessable patients received at least 5 days of 2-CdA. Fourteen patients received more than one cycle of 2-CdA. An overall response rate of 28% was achieved. Three patients (14%) had a complete response with a median duration of 4.5 months (range, 2.5 to 16). Three (14%) had a partial response with a median duration of 2 months (range, 2 to 4). Fifteen patients (72%) had no response. The most significant toxicities encountered were bone marrow suppression (62% of patients) and infectious complications (62% of patients). Thirty-eight percent of patients experienced no toxicity from 2-CdA. 2-CdA has activity as a single agent in patients with previously treated relapsed MF/SS. Studies in less heavily pretreated individuals with 2-CdA alone or in combination will be undertaken.  相似文献   
64.

Background

Chagas disease is a cause of dilated cardiomyopathy, and information about left atrial (LA) function in this disease still lacks.

Objective

To assess the different LA functions (reservoir, conduit and pump functions) and their correlation with the echocardiographic parameters of left ventricular (LV) systolic and diastolic functions.

Methods

10 control subjects (CG), and patients with Chagas disease as follows: 26 with the indeterminate form (GI); 30 with ECG alterations (GII); and 19 with LV dysfunction (GIII). All patients underwent M-mode and two-dimensional echocardiography, pulsed-wave Doppler and tissue Doppler imaging.

Results

Reservoir function (Total Emptying Fraction: TEF): (p <0.0001), lower in GIII as compared to CG (p = 0.003), GI (p <0.001) and GII (p <0.001). Conduit function (Passive Emptying Fraction: PEF): (p = 0.004), lower in GIII (GIII and CG, p = 0.06; GI and GII, p = 0.06; and GII and GIII, p = 0.07). Pump function (Active Emptying Fraction: AEF): (p = 0.0001), lower in GIII as compared to CG (p = 0.05), GI (p<0.0001) and GII (p = 0.002). There was a negative correlation of E/e’average with the reservoir and pump functions (TEF and AEF), and a positive correlation of e’average with s’ wave (both septal and lateral walls) and the reservoir, conduit and pump LA functions.

Conclusion

An impairment of LA functions in Chagas cardiomyopathy was observed.  相似文献   
65.
We have previously described a unique type of delta beta-thalassemia in a Chinese family characterized by increased expression of the G gamma and A gamma fetal globin genes in the absence of a large deletion in the beta-globlin gene cluster. Our earlier study of the beta-globin gene on this delta beta-thalassemia chromosome showed a promoter mutation in the TATA box. In this report, we describe the results of our study of the fetal globin domain of this delta beta-thalassemia chromosome. We have cloned a 13-kb DNA fragment that includes the G gamma and the A gamma genes and the 3' A gamma enhancer element of this delta beta-thalassemia chromosome. DNA sequence analysis of the G gamma and A gamma-globin genes including their promoters did not show any mutations, but analysis of the putative enhancer element downstream from the A gamma-globin gene showed a C to T substitution 2,401 nucleotides downstream from the A gamma cap site. We performed DNA linkage analysis to determine if this mutation is unique to this chromosome or represents a common polymorphism. Our linkage analysis showed that this mutation is not a common polymorphism and that it is also not an intrinsic part of the haplotype of the chromosome on which it was found. We also studied the interaction of nuclear proteins from erythroid and nonerythroid cells with the DNA sequences surrounding this mutation. We have shown by in vitro DNase I footprinting that this mutation falls within a region that is occupied by a novel DNA-binding protein that binds to this site in nuclear extracts from erythroid, but not nonerythroid cells. The binding of this nuclear protein to DNA appears to be dependent on GATA-1 binding to an adjacent GATA-1 site. We have also developed a new functional assay to compare the activity of the normal and mutant A gamma enhancer elements in erythroid cells. Analysis of the activity of the mutant enhancer shows that the mutation completely eliminates all enhancer activity in this assay. These findings suggest that this mutation of the A gamma enhancer on a chromosome that carries a partially inactivated beta-globin gene may be responsible for the increased expression of both gamma-globin genes seen in this condition.  相似文献   
66.
BACKGROUND: Pure, benign epidermoid cysts of the abdominal viscera are rare. There have been only four reports of epidermoid cysts of the cecum in the literature, two following appendectomies and attributed to the surgical procedure, and two in female patients, raising the possibility of dermoid cysts related to the ovaries. PATIENTS AND METHODS: We report the first case of epidermoid cyst of the cecum in an elderly man with no previous history of trauma or surgery, detected by computed tomography as an incidental finding of extraluminal cystic cecal mass. It was treated by partial colectomy. Pathologically the cyst was roughly spherical, extending from and expanding the serosal surface of the cecum with no communication through the muscularis wall. Histologically the inner lining of the cyst was composed of benign, mature, keratinized, stratified squamous epithelium with a well formed granular layer. No calcification, hair, teeth, or bone elements was detected. RESULTS: The interesting finding in our case is the unusual anatomical location and the age and sex of the patient. The patient had no history of any abdominal surgical procedures. The most likely explanation for the presence and development of an epidermoid cyst in this location is the result of an aberrant ectodermal implantation during embryogenesis. CONCLUSION: Awareness of the possibility of the presence of epidermoid cysts in this area with distinctive radiological findings consistent with a well circumscribed benign cyst should be considered in the differential diagnosis of cysts within the abdomen.  相似文献   
67.
Interaction of platelet plasma membranes with thrombin-activated platelets   总被引:1,自引:0,他引:1  
Prasanna  HR; Edwards  HH; Phillips  DR 《Blood》1981,57(2):305-312
This study described the binding of platelet plasma membranes to either control or thrombin-activated platelets. Glycoproteins in plasma membranes isolated from human platelets were labeled by oxidation with periodate followed by reduction with [3H]NaBH4. Labeled membranes were incubated with either control or thrombin-activated platelets. The amount of membranes bound was measured by separating platelets with bound membranes from solution by rapid centrifugation through 27% sucrose and determining the amount of radioactivity associated with platelets. Five- to sevenfold more membranes bound to thrombin- activated platelets than to control platelets. This enhanced binding of labeled membranes was completely inhibited by an excess of unlabeled platelet membranes. Human erythrocyte membranes had little affinity for either washed or thrombin-activated platelets and therefore did not compete for platelet-membrane binding. Binding of platelet membranes to thrombin-treated platelets was inhibited by prior incubation of the platelets with PGI2 suggesting that the enhanced binding of membranes was to activated platelets. This study demonstrates that the purified platelet membranes have functional sites that can mediate membrane binding to platelets and that quantitation of membrane binding appears to reflect the increased aggregation capability of activated platelets.  相似文献   
68.
69.

Background

The epidemiological characteristics of thoracic aortic diseases (TAD) in the State of São Paulo and in Brazil, as well as their impact on the survival of these patients have yet to be analyzed.

Objectives

To evaluate the mortality impact of TAD and characterize it epidemiologically.

Methods

Retrospective analysis of data from the public health system for the TAD registry codes of hospitalizations, procedures and deaths, from the International Code of Diseases (ICD-10), registered at the Ministry of Health of São Paulo State from January 1998 to December 2007.

Results

They were 9.465 TAD deaths, 5.500 men (58.1%) and 3.965 women (41.9%); 6.721 dissections (71%) and 2.744. aneurysms. In 86.3% of cases the diagnosis was attained during autopsy. There were 6.109 hospitalizations, of which 67.9% were males; 21.2% of them died (69% men), with similar proportions of dissection and aneurysm between sexes, respectively 54% and 46%, but with different mortality. Men with TAD die more often than women (OR = 1.5). The age distribution for deaths and hospitalizations was similar with predominance in the 6th decade. They were 3.572 surgeries (58% of hospitalizations) with 20.3% mortality (patients kept in clinical treatment showed 22.6% mortality; p = 0.047). The number of hospitalizations, surgeries, deaths of in-patients and general deaths by TAD were progressively greater than the increase in population over time.

Conclusions

Specific actions for the early identification of these patients, as well as the viability of their care should be implemented to reduce the apparent progressive mortality from TAD seen among our population.  相似文献   
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