全文获取类型
收费全文 | 1503篇 |
免费 | 179篇 |
国内免费 | 28篇 |
专业分类
耳鼻咽喉 | 6篇 |
儿科学 | 143篇 |
妇产科学 | 24篇 |
基础医学 | 202篇 |
口腔科学 | 90篇 |
临床医学 | 158篇 |
内科学 | 287篇 |
皮肤病学 | 49篇 |
神经病学 | 30篇 |
特种医学 | 173篇 |
外科学 | 228篇 |
综合类 | 38篇 |
预防医学 | 94篇 |
眼科学 | 40篇 |
药学 | 53篇 |
中国医学 | 2篇 |
肿瘤学 | 93篇 |
出版年
2023年 | 14篇 |
2022年 | 10篇 |
2021年 | 13篇 |
2020年 | 14篇 |
2019年 | 7篇 |
2018年 | 44篇 |
2017年 | 46篇 |
2016年 | 41篇 |
2015年 | 62篇 |
2014年 | 76篇 |
2013年 | 108篇 |
2012年 | 48篇 |
2011年 | 30篇 |
2010年 | 77篇 |
2009年 | 91篇 |
2008年 | 28篇 |
2007年 | 48篇 |
2006年 | 47篇 |
2005年 | 25篇 |
2004年 | 28篇 |
2003年 | 14篇 |
2002年 | 21篇 |
2001年 | 16篇 |
2000年 | 11篇 |
1999年 | 24篇 |
1998年 | 102篇 |
1997年 | 86篇 |
1996年 | 98篇 |
1995年 | 63篇 |
1994年 | 74篇 |
1993年 | 39篇 |
1992年 | 14篇 |
1991年 | 21篇 |
1990年 | 13篇 |
1989年 | 31篇 |
1988年 | 29篇 |
1987年 | 28篇 |
1986年 | 26篇 |
1985年 | 24篇 |
1984年 | 12篇 |
1983年 | 9篇 |
1982年 | 20篇 |
1981年 | 15篇 |
1980年 | 16篇 |
1979年 | 5篇 |
1978年 | 6篇 |
1977年 | 9篇 |
1976年 | 13篇 |
1975年 | 9篇 |
1966年 | 1篇 |
排序方式: 共有1710条查询结果,搜索用时 15 毫秒
991.
Bollen J Polstra A Van Der Kuyl A Weel J Noorduyn L Van Oers M Cornelissen M 《BMC blood disorders》2003,3(1):3
Background
Multicentric Castleman's disease (MCD) is a rare disease, but is more frequent in AIDS patients. MCD has only been reported twice before in patients receiving immunosuppressive therapy after renal transplantation, and never in patients receiving immunosuppressive therapy without transplantation. About half of the cases of MCD are human herpesvirus 8 (HHV8) – related, in contrast to Kaposi's sarcoma, a more common complication arising after immunosuppression, where the virus is found in virtually all cases. 相似文献992.
AM Havens Y Jung YX Sun J Wang RB Shah HJ Bühring KJ Pienta RS Taichman 《BMC cancer》2006,6(1):195-13
Background
The chemokine stromal derived factor-1 (SDF-1 or CXCL12) and its receptor CXCR4 have been demonstrated to be crucial for the homing of stem cells and prostate cancers to the marrow. While screening prostate cancers for CXCL12-responsive adhesion molecules, we identified CD164 (MGC-24) as a potential regulator of homing. CD164 is known to function as a receptor that regulates stem cell localization to the bone marrow. 相似文献993.
hMLH1 and hMSH2 expression and BAX frameshift mutations in ovarian cancer cell lines and tumors 总被引:2,自引:0,他引:2
Colella G; Vikhanskaya F; Codegoni AM; Bonazzi C; D'Incalci M; Broggini M 《Carcinogenesis》1998,19(4):691-694
The expression of mismatch repair proteins hMSH2 and hMLH1 was investigated
in human ovarian cancer cell lines and in biopsies of ovarian carcinomas
obtained from 20 patients undergoing surgical operation. By Western
blotting analysis hMSH2 protein was detected in all the tumor samples
analyzed and in eight out of nine human ovarian cancer cell lines, while
hMLH1 was undetectable in four out of 20 ovarian tumors and in five out of
nine human ovarian cancer cell lines analyzed. The possible presence of
frameshift mutations in the BAX gene, which contains a sequence of eight
contiguous guanines in its third exon, was tested in all the samples. All
the cell lines presented the normal alleles for the BAX gene while only in
one of the tumor samples a heterozygous frameshift mutation was found. The
frameshift mutation was associated to a low, almost undetectable, level of
BAX protein which was instead present at much higher levels in all the
other samples investigated. The results indicate that frameshift mutations
in the BAX gene, possibly arising as a consequence of microsatellite
instability (detectable in these tumors), is detectable in human ovarian
cancer although quantitatively it does not appear to be a major determinant
of the low apoptotic response to chemotherapy observed in ovarian cancer
cells.
相似文献
994.
The effects of H2O2-induced oxidative DNA damage in 80 healthy individuals
with relation to age (20-25 and 55-60 years old) and smoking has been
investigated with the comet assay technique. Both factors have shown a
significant effect upon basal DNA damage with smoking appearing to have the
most impact. A differentiation of the four groups response to induced
oxidative damage was also observed. A distinctly separate behavior of the
younger non-smokers group, when compared with the rest of the categories,
was found. This is attributed to the lower degree of initial basal damage
that occurs in their lymphocytes.
相似文献
995.
To study the effects of carotenoids on the initiation of liver
carcinogenesis by aflatoxin B1 (AFB1), male weanling rats were fed beta-
carotene, beta-apo-8'-carotenal, canthaxanthin, astaxanthin or lycopene
(300 mg/kg diet), or an excess of vitamin A (21000 RE/kg diet), or were
injected i.p. with 3-methylcholanthrene (3-MC) (6 x 20 mg/kg body wt)
before and during i.p. treatment with AFB1 (2 x 1 mg/kg body wt). The rats
were later submitted to 2-acetylaminofluorene treatment and partial
hepatectomy, and placental glutathione S-transferase-positive liver foci
were detected and quantified. The in vivo effects of carotenoids or of 3-MC
on AFB1-induced liver DNA damage were evaluated using different endpoints:
liver DNA single-strand breaks (SSB) induced by AFB1, and in vivo binding
of [3H]AFB1 to liver DNA and plasma albumin. Finally, the modulation of
AFB1 metabolism by carotenoids or by 3-MC was investigated in vitro by
incubating [14C]AFB1 with liver microsomes from rats that had been fed with
carotenoids or treated by 3- MC, and the metabolites formed by HPLC were
analyzed. In contrast to lycopene or to an excess of vitamin A, both of
which had no effect, beta-carotene, beta-apo-8'carotenal, astaxanthin and
canthaxanthin, as well as 3-MC, were very efficient in reducing the number
and the size of liver preneoplastic foci. In a similar way as 3-MC, the
P4501A- inducer carotenoids, beta-apo-8'-carotenal astaxanthin and
canthaxanthin, decreased in vivo AFB1-induced DNA SSB and the binding of
AFB1 to liver DNA and plasma albumin, and increased in vitro AFB1
metabolism to aflatoxin M1, a less genotoxic metabolite. It is concluded
that these carotenoids exert their protective effect through the deviation
of AFB1 metabolism towards detoxication pathways. In contrast,
beta-carotene did not protect hepatic DNA from AFB1-induced alterations,
and caused only minor changes of AFB1 metabolism: seemingly, its protective
effect against the initiation of liver preneoplastic foci by AFB1 is
mediated by other mechanisms.
相似文献
996.
MH Cnossen A de Goede-Bolder KM van den Broek CM Waasdorp AP Oranje H Stroink HJ Simonsz AM van den Ouweland DJ Halley MF Niermeijer 《Archives of disease in childhood》1998,78(5):408-412
OBJECTIVE: To establish the prevalence and incidence of symptoms and complications in children with neurofibromatosis type 1 (NF1) and to assess possible risk factors for the development of complications. DESIGN: A 10 year prospective multidisciplinary follow up study. PATIENTS: One hundred and fifty children diagnosed with NF1 according to criteria set by the National Institutes of Health. RESULTS: In 62 of 150 children (41.3%) complications were present, including 42 (28.0%) children with one complication, 18 (12.0%) with two complications, and two (1.3%) with three complications (mean (SD) duration of follow up 4.9 (3.8) years). Ninety five of the 150 children presented without complications (follow up, 340.8 person-years). The incidence of complications was 2.4/100 person-years in this group. An association was found between behavioural problems and the presence of complications. CONCLUSION: This is the largest single centre case series of NF1 affected children followed until 18 years of age. Children with NF1, including those initially presenting without complications, should have regular clinical examinations. 相似文献
997.
Jane B Morgan AC Kimber AM Redfern BJ Stordy 《Acta paediatrica (Oslo, Norway : 1992)》1995,84(5):512-515
Mothers'perceptions of desirable nutritional practices in infant feeding were examined using a questionnaire consisting of open and closed questions. A total of 1004 mother–infant pairs were recruited from a mixture of urban and rural areas in England. The sample represented a cross–section of socioeconomic groups and educational backgrounds. Mothers'attitudes to healthy eating for infants revealed some misconceptions; 83% felt that a high fibre intake was important or very important and 87% that a low fat intake was important or very important, while 20% considered that plenty of calories was not important. Other health guidelines were appropriately applied and most mothers considered a wide variety of foods, plenty to drink and a low sugar and salt intake to be important. These beliefs were representative of the sample population, irrespective of the socioeconomic group, location, age and education of the mother. 相似文献
998.
The causes, classification, and prevention of mechanical asphyxial death in children were examined. The Office of Population Censuses and Surveys (OPCS) identified children, under 15 years of age, who had died as a result of choking, suffocation, or strangulation in England and Wales during the years 1990 and 1991. Cases in the International Classification of Diseases (ICD) codes of E911-3, E953, E963, and E983 were selected and case details from HM coroners' records and the death certificates were extracted. The OPCS identified 136 children (99 boys, 37 girls) in the two year period, 65% were under 3 years of age. The children were classified as dying from choking (21 cases), aspirating gastric contents (39 cases), suffocation (29 cases), strangulation (11 cases), and hanging (36 cases). The strangulation cases could be further subdivided into a group of 12 younger children who were suspended from ligatures around the home and a group of 21 boys (8-14 years) who died of self initiated hanging. Overall, 11 children were deliberately killed and 31 children died in beds or cots. Children whose deaths are classified as being due to aspiration of vomit appear to be cases of the sudden infant death syndrome or background medical conditions. This study suggests the need for advice on maintaining a safe sleeping environment. Only one child choked on a toy and European Standards for Toy Safety appear to have been successful. The prevention of hanging in the group of older boys needs further exploration. 相似文献
999.
GM Taylor SP Dearden AM Will DI Evans RF Stevens S Simon M Super G Morrell WD Fergusson IH Brown 《Archives of disease in childhood》1995,73(5):453-455
The successful correction of infantile osteopetrosis in an Asian child by bone marrow transplantation (BMT) from an HLA-A,B matched cousin donor is reported. Retrospective HLA molecular analysis revealed that patient and donor were incompatible for HLA-DPB1. Donor type cells detected in the patient after transplantation indicate successful engraftment. The patient is currently alive and well. 相似文献
1000.
AJ Green JR Yates AM Taylor P Biggs GM McGuire CM McConville CJ Billing ND Barnes 《Archives of disease in childhood》1995,73(5):431-434
A brother and sister are described with severe microcephaly of prenatal onset, normal intellectual and motor development, chromosomal breakage and cellular immunodeficiency, which is characteristic of the autosomal recessive condition, Nijmegen breakage syndrome. The proband was a girl who presented at 15 months, with normal developmental milestones and an extremely small head circumference of 36 cm. Twenty per cent of her lymphocytes showed spontaneous translocations involving chromosome 7p13, 7q35, 14q11, and 14q32. The lymphocytes also showed excessive x ray induced chromosome damage. She had T cell lymphopenia, but normal immunoglobulins, and a normal alpha fetoprotein. A brother was born shortly after her diagnosis was made. He also had extreme microcephaly of 28 cm, with similar spontaneous and x ray induced chromosomal breakage, and T cell lymphopenia. Neither child has clinical evidence of immunodeficiency. To test the hypothesis that Nijmegen breakage syndrome and ataxia telangiectasia are allelic disorders, haplotype analysis was carried out in the family using DNA markers spanning the AT locus on chromosome 11q22. The affected boy had a different haplotype from his affected sister. Thus in this family, the Nijmegen breakage syndrome is not allelic to the ataxia telangiectasia locus on chromosome 11q, and the two conditions are genetically distinct. The normal intellect in these children raises questions about normal brain development in the presence of severe microcephaly. 相似文献