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   28884篇
  免费   2036篇
  国内免费   139篇
耳鼻咽喉   417篇
儿科学   715篇
妇产科学   556篇
基础医学   4330篇
口腔科学   500篇
临床医学   2510篇
内科学   5529篇
皮肤病学   655篇
神经病学   2578篇
特种医学   1150篇
外科学   4060篇
综合类   638篇
现状与发展   1篇
一般理论   30篇
预防医学   1895篇
眼科学   750篇
药学   2156篇
中国医学   183篇
肿瘤学   2406篇
  2023年   179篇
  2022年   471篇
  2021年   802篇
  2020年   375篇
  2019年   620篇
  2018年   729篇
  2017年   500篇
  2016年   736篇
  2015年   868篇
  2014年   1051篇
  2013年   1374篇
  2012年   2038篇
  2011年   1870篇
  2010年   1139篇
  2009年   1017篇
  2008年   1597篇
  2007年   1552篇
  2006年   1401篇
  2005年   1474篇
  2004年   1406篇
  2003年   1273篇
  2002年   1111篇
  2001年   600篇
  2000年   566篇
  1999年   481篇
  1998年   287篇
  1997年   215篇
  1996年   207篇
  1995年   217篇
  1994年   157篇
  1993年   181篇
  1992年   312篇
  1991年   269篇
  1990年   271篇
  1989年   265篇
  1988年   248篇
  1987年   221篇
  1986年   222篇
  1985年   240篇
  1984年   181篇
  1983年   144篇
  1982年   150篇
  1981年   157篇
  1980年   134篇
  1979年   122篇
  1977年   100篇
  1976年   124篇
  1975年   104篇
  1974年   134篇
  1973年   101篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
951.
This study reports on the regulation and remodeling role of endothelin-1 (ET-1) and its receptor subtypes, ET(A)-Rs/ET(B)-Rs, at the coronary endothelium (CE) and cardiomyocyte (CM) sites. It is carried out in normal and normotensive rats with streptozotocin-induced diabetes mellitus receiving different treatment modalities. Normal rats were divided into two groups, namely a placebo (N) and a losartan-treated (NL), and diabetic rats into four groups receiving placebo (D), insulin-treated (DI), losartan-treated (DL), and insulin/losartan-treated (DIL) respectively. Binding kinetics of ET-1 to ET(A)-Rs/ET(B)-Rs on CE and CMs were assessed in the above groups to try to explain the effect of therapeutic doses of an angiotensin II receptor subtype-1 blocker on the dynamics of this ligand and its receptor in insulin supplemented diabetic animals. Each group was divided into two subgroups: CHAPS-untreated and CHAPS-treated rat hearts perfused with [125I]ET-1 to respectively estimate ET-1 binding affinity (tau = 1/k-n) to its receptor subtype(s) on CE and CMs using mathematical modeling describing a 1:1 reversible binding stoichiometry. Heart perfusion results revealed that insulin treatment significantly decreased tau on CE but not on CMs in diabetic rats. In diabetics treated with losartan, an increase in tau value on CE but not on CMs was noted. Cotreatment of diabetic rats with insulin and losartan normalized tau on CE but decreased it on CMs. Western blot, using snap-frozen heart tissues, revealed increase in ET(A)-R density in all diabetic groups. However, significant decrease in ET(B)-R density was observed in all groups compared to the normal, and was reconfirmed by immunohistochemical analysis. In conclusion, coadministration of insulin and losartan in nonhypertensive animals suffering from diabetes type 1 may offer new cardiac protection benefits by improving coronary blood flow and cardiomyocyte contractility through modulating ET-1 receptor subtypes density and affinity at CE and CM sites.  相似文献   
952.
953.
What is the recommended diagnostic work-up of female genital anomalies according to the European Society of Human Reproduction and Embryology (ESHRE)/European Society for Gynaecological Endoscopy (ESGE) system? The ESHRE/ESGE consensus for the diagnosis of female genital anomalies is presented. Accurate diagnosis of congenital anomalies still remains a clinical challenge due to the drawbacks of the previous classification systems and the non-systematic use of diagnostic methods with varying accuracy, with some of them quite inaccurate. Currently, a wide range of non-invasive diagnostic procedures are available, enriching the opportunity to accurately detect the anatomical status of the female genital tract, as well as a new objective and comprehensive classification system with well-described classes and sub-classes. The ESHRE/ESGE Congenital Uterine Anomalies (CONUTA) Working Group established an initiative with the goal of developing a consensus for the diagnosis of female genital anomalies. The CONUTA working group and imaging experts in the field have been appointed to run the project. The consensus is developed based on (1) evaluation of the currently available diagnostic methods and, more specifically, of their characteristics with the use of the experts panel consensus method and of their diagnostic accuracy performing a systematic review of evidence and (2) consensus for (a) the definition of where and how to measure uterine wall thickness and (b) the recommendations for the diagnostic work-up of female genital anomalies, based on the results of the previous evaluation procedure, with the use of the experts panel consensus method. Uterine wall thickness is defined as the distance between interostial line and external uterine profile at the midcoronal plane of the uterus; alternatively, if a coronal plane is not available, the mean anterior and posterior uterine wall thickness at the longitudinal plane could be used. Gynaecological examination and two-dimensional ultrasound (2D US) are recommended for the evaluation of asymptomatic women. Three-dimensional ultrasound (3D US) is recommended for the diagnosis of female genital anomalies in “symptomatic” patients belonging to high-risk groups for the presence of a female genital anomaly and in any asymptomatic woman suspected to have an anomaly from routine avaluation. Magnetic resonance imaging (MRI) and endoscopic evaluation are recommended for the sub-group of patients with suspected complex anomalies or in diagnostic dilemmas. Adolescents with symptoms suggestive for the presence of a female genital anomaly should be thoroughly evaluated with 2D US, 3D US, MRI and endoscopy. The various diagnostic methods should be used in a proper way and evaluated by experts to avoid mis-, over- and underdiagnosis. The role of a combined ultrasound examination and outpatient hysteroscopy should be prospectively evaluated. It is a challenge for further research, based on diagnosis, to objectively evaluate the clinical consequences related to various degrees of uterine deformity.  相似文献   
954.
BackgroundAtopic dermatitis (AD) is a heterogeneous disease with different age of onset, disease course, clinical symptoms, severity, and risk of comorbidity. The characteristics of children with AD also vary by age or country. However, little is known about the clinical characteristics of AD in Korean school-aged children and adolescents. Furthermore, there are few studies on phenotypic differences according to onset age. This study aimed to explore the clinical characteristics and phenotypes according to onset age and severity of AD in children and adolescents in Korea.MethodsAD patients aged 6–18 years who presented to 18 hospitals nationwide were surveyed. The patients were examined for disease severity by pediatric allergy specialists, and data on history of other allergic diseases, familial allergy history, onset age, trigger factors, lesion sites, treatment history and quality of life were collected. The results of the patient’s allergy test were also analyzed. The patients were classified into infancy-onset (< 2 years of age), preschool-onset (2–5 years of age), and childhood-onset (≥ 6 years of age) groups. Study population was analyzed for clinical features according to onset-age groups and severity groups.ResultsA total of 258 patients with a mean age of 10.62 ± 3.18 years were included in the study. Infancy-onset group accounted for about 60% of all patients and presented significantly more other allergic diseases, such as allergic rhinitis and asthma (P = 0.002 and P = 0.001, respectively). Food allergy symptoms and diagnoses were highly relevant to both earlier onset and more severe group. Inhalant allergen sensitization was significantly associated with both infancy-onset group and severe group (P = 0.012 and P = 0.024, respectively). A family history of food allergies was significantly associated with infancy-onset group (P = 0.036). Severe group was significantly associated with a family history of AD, especially a paternal history of AD (P = 0.048 and P = 0.004, respectively). Facial (periorbital, ear, and cheek) lesions, periauricular fissures, hand/foot eczema, and xerosis were associated with infancy-onset group. The earlier the onset of AD, the poorer the quality of life (P = 0.038). Systemic immunosuppressants were used in only 9.6% of the patients in the severe group.ConclusionThis study analyzed the clinical features of AD in Korean children and adolescents through a multicenter nationwide study and demonstrated the phenotypic differences according to onset age and severity. Considering the findings that the early-onset group is more severe and accompanied by more systemic allergic diseases, early management should be emphasized in young children and infants.  相似文献   
955.
Virus associated hemophagocytic syndrome (VAHS) are a heterogeneous group of disorders in which viral infection is associated with a proliferation of hemophagocytic histiocytes through the reticuloendothelial system. We report the case of a 21-year-old Korean man who presented to us with high fever, marked hepatosplenomegaly, severe hepatic dysfunction, coagulopathy, pancytopenia and marked panhypogammaglobulinemia. Bone marrow aspiration and biopsy showed histiocytes proliferation with active phagocytosis of red cells and neutrophils. Primary Epstein-Barr (EB) viral infection at presentation was confirmed by the presence of IgM antibody to viral capsid antigen (VCA) with absence of antibody to EB viral nuclear antigen (EBNA). A liver biopsy performed one month after the presentation showed erythrophagocytic histiocytes within the sinusoids. EB virus was demonstrated in the liver biopsy tissue by DNA PCR method, and EBER mRNA in situ hybridization.  相似文献   
956.
Virus-specific cytotoxic T lymphocytes were generated in two strains of mice (BALB/c and CBA/Ca) against baculovirus recombinant proteins (minor and nonstructural) derived from bluetongue virus serotype 10. Immunization of mice with recombinant baculovirus insect cell extracts expressing the nonstructural protein NS2 (Bac-NS2) conferred partial protection against infection with vaccinia virus expressing the NS2 protein. This protective immunity was mediated by CD8+ cells. In contrast, no protection was observed when mice were immunized with similarly expressed Bac-NS1 or -NS3 or the virion minor structural proteins (Bac-VP1, -VP4, or -VP6). Furthermore, the in vitro cytotoxicity activity of T cells derived from immunized animals did not correlate to the protective efficacy of baculovirus recombinant proteins. The implications of this work with regard to the design of noninfectious subunit vaccines are discussed.  相似文献   
957.
Our objectives were to describe fetal cases of vertebral defects (VD), assess the diagnostic yield of fetal chromosomal analysis for VD and determine which investigations should be performed when evaluating fetal VD. We performed a retrospective chart review for fetuses with VD seen between 2006 and 2015. Cases were identified from CHU Sainte‐Justine's prenatal clinic visits, postmortem fetal skeletal surveys, and medical records. Cases with neural tube defects were excluded. Sixty‐six fetuses with VD were identified at a mean gestational age of 20 weeks. Forty‐seven (71.2%) had associated antenatal anomalies, most commonly genitourinary, skeletal/limb, and cardiac anomalies. Thirteen mothers (19.7%) had pregestational diabetes (95% CI [10.1%–29.3%]). Fifty‐three cases had chromosomal analysis. Three had abnormal results (5.6%): trisomy 13, trisomy 22, and 9q33.1q34.11 deletion. Thirty‐four (51.5%) pregnancies were terminated, one led to intrauterine fetal demise and 31 (46.9%) continued to term. Of 27 children who survived the neonatal period, 21 had congenital scoliosis and 3 had spondylocostal dysostosis. Seven had developmental delay. In conclusion, prenatal evaluation of fetuses with VD should include detailed morphological assessment (including fetal echocardiogram), maternal diabetes screening, and chromosomal microarray if non‐isolated. Our findings provide guidance about management and counseling after a diagnosis of fetal VD.  相似文献   
958.
Das S  Ghosh R  Paul S  Roy A  Ghosh SK 《Archives of virology》2008,153(9):1791-1796
Yellow vein mosaic disease of mesta in northern India was found to be associated with a distinct begomovirus species. Except the AC1 gene, this begomovirus isolate shares low sequence identity with the Mesta yellow vein mosaic virus reported to be associated with a similar disease of mesta from eastern India.  相似文献   
959.
In the present study, the authors investigated the management of mechanical valve thrombosis (MVT). From January 1981 through March 2006, 2,908 mechanical valve replacements were performed in 2,298 patients at our institution. Twenty (0.87%) patients presented with MVT, 14 (70.0%) were women, and the mean age of the patients was 42.0+/-14.0 (27-66) yr. Thrombosis involved mitral in 14 (70.0%), aortic in 2 (10.0%), tricuspid/aortic in 1 (5%), and tricuspid in 3 (15%). The interval from first operation to valve thrombosis was 121.8+/-75.4 (0.9-284.7) months. The most frequent clinical presentation was heart failure (13/20, 65%), and predisposing causes of MVT were: poor compliance with warfarin (7), pregnancy (5), drug interaction (2), and unknown (6). All 20 patients underwent valve replacement: mitral (14, 70.0%), tricuspid (3, 15.0%), aortic (2, 10%) and tricuspid/aortic (1, 5%). One early death occurred due to left ventricular failure, but no late mortality occurred during 63.3+/-49.9 (0.5-165.1) months of follow-up. MVT was treated successfully, and pregnancy and inadequate anticoagulation were found to influence the occurrence of this rare complication.  相似文献   
960.
Co-infections with HIV-1 and the human T leukemia virus types 1 and 2 (HTLV-1, HTLV-2) occur frequently, particularly in large metropolitan areas where injection drug use is a shared mode of transmission. Recent evidence suggests that HIV-HTLV co-infections are associated with upregulated HTLV-1/2 virus expression and disease. An in vitro model of HIV-1 and HTLV-1/2 co-infection was utilized to determine if cell free HIV-1 virions or recombinant HIV-1 Tat protein (200-1,000 ng/ml) upregulated HTLV-1/2 expression and infectivity. Exposure to HIV-1 increased the number of HTLV-1 antigen expressing cells, from 6% at baseline to 12% at 24 hr, and 20% at 120 hr (P < 0.05) post-exposure. A similar, although less robust response was observed in HTLV-2 infected cells. HIV-1 co-localized almost exclusively with HTLV-1/2 positive cells. Exposure to HIV-1 Tat protein (1,000 ng/ml) increased HTLV-1 p19 expression almost twofold by 48 hr, and cells co-stimulated with 10 nM phorbol myristate acetate (PMA) showed almost a fourfold increase over baseline. It is concluded that HIV-1 augments HTLV-1/2 infectivity in vitro. The findings also suggest a role for the HIV-1 Tat protein and PMA-inducible cellular factors, in HIV-1 induced HTLV-1/2 antigen expression.  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