全文获取类型
收费全文 | 15650篇 |
免费 | 1331篇 |
国内免费 | 1266篇 |
专业分类
耳鼻咽喉 | 107篇 |
儿科学 | 164篇 |
妇产科学 | 230篇 |
基础医学 | 1905篇 |
口腔科学 | 333篇 |
临床医学 | 2244篇 |
内科学 | 2543篇 |
皮肤病学 | 125篇 |
神经病学 | 855篇 |
特种医学 | 702篇 |
外国民族医学 | 11篇 |
外科学 | 1691篇 |
综合类 | 2387篇 |
现状与发展 | 3篇 |
一般理论 | 3篇 |
预防医学 | 878篇 |
眼科学 | 369篇 |
药学 | 1566篇 |
12篇 | |
中国医学 | 809篇 |
肿瘤学 | 1310篇 |
出版年
2024年 | 50篇 |
2023年 | 259篇 |
2022年 | 659篇 |
2021年 | 874篇 |
2020年 | 576篇 |
2019年 | 526篇 |
2018年 | 563篇 |
2017年 | 444篇 |
2016年 | 454篇 |
2015年 | 686篇 |
2014年 | 857篇 |
2013年 | 713篇 |
2012年 | 1098篇 |
2011年 | 1215篇 |
2010年 | 713篇 |
2009年 | 662篇 |
2008年 | 794篇 |
2007年 | 810篇 |
2006年 | 754篇 |
2005年 | 778篇 |
2004年 | 492篇 |
2003年 | 493篇 |
2002年 | 443篇 |
2001年 | 343篇 |
2000年 | 396篇 |
1999年 | 446篇 |
1998年 | 294篇 |
1997年 | 279篇 |
1996年 | 230篇 |
1995年 | 225篇 |
1994年 | 156篇 |
1993年 | 127篇 |
1992年 | 129篇 |
1991年 | 90篇 |
1990年 | 86篇 |
1989年 | 95篇 |
1988年 | 68篇 |
1987年 | 83篇 |
1986年 | 57篇 |
1985年 | 56篇 |
1984年 | 34篇 |
1983年 | 21篇 |
1982年 | 9篇 |
1981年 | 14篇 |
1980年 | 18篇 |
1979年 | 11篇 |
1978年 | 5篇 |
1968年 | 4篇 |
1964年 | 4篇 |
1931年 | 6篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
41.
Idiopathic thrombocytopenic purpura (ITP), caused by autoantibodies directed against certain platelet antigens, is the most common entity of the immune thrombocytopenias. ITP is an acquired disorder and can affect both children and adults. However, the clinical syndromes of ITP are distinct between children and adults. Childhood (acute) ITP characteristically is acute in onset, occurs within 1-2 weeks of an infection, usually of viral origin, resolves spontaneously within 6 months. Adult (chronic) ITP has an insidious onset and rarely resolves spontaneously. Over the last decade considerable new information has accumulated as to the pathophysiological mechanisms of immune thrombocytopenias. In addition, most of the knowledge on this disorder has been obtained from studies of adult patients with chronic ITP. The present work gives an updated overview of the platelet autoantigens and the molecular immunological reactions in ITP. 相似文献
42.
OBJECTIVE: Because survival from admission to discharge does not provide parents and physicians information about future life expectancy in the premature neonate, we characterized the actuarial survival, defined as the future life expectancy from a given postnatal age, in a large inborn population of premature infants < 30 weeks' gestation. STUDY DESIGN: We determined daily actuarial survival of 1925 inborn infants (23 to 29 weeks' gestation) admitted to the Baylor Affiliated Nurseries from July 1986 through December 1994, stratified by 100-g birth weight and by 1-week gestational-age intervals. RESULTS: In the 501- to 600-g birth weight stratum, actuarial survival improved from 31% at birth, to 61% on day of life 7, and then to 75% on day of life 28; in the 901- to 1000-g birth weight stratum, actuarial survival improved from 88%, to 94%, and then to 98% throughout the same times, respectively. Similar trends were obtained when data were stratified by gestational age. CONCLUSIONS: Survival in the smallest infants improves dramatically during the first few days of life, but there is a significant risk for late death in the smallest of these infants. 相似文献
43.
Recent molecular cytogenetic studies have elucidated the origin and nature of extra structurally abnormal chromosomes (ESACs)
or small supernumerary chromosomes, which are often associated with developmental delay and malformations. We studied the
prevalence of inv dup(15) in a nationwide screening programme for mentally retarded children in Taiwan and tried to correlate
the genotype and phenotype in those patients. Fluorescence in situ hybridization (FISH) analysis using D15Z, D15Z1, and the
cosmids from the Prader-Willi/Angelman syndrome chromosome region (PW/ASCR) was performed on 54 patients (0.45%) with ESACs
from 11893 probands within a 5-year period. Of them, inv dup(15) was confirmed in 25 children (46.3%) by FISH analysis. The
PW/ASCR probes were used to clarify the size and DNA composition of the markers. Patients with inv dup(15) chromosomes, containing
only the heterochromatin or little euchromatin of the proximal 15q (i.e., pter→q11:q11→pter) may have a rather mild or nearly
normal phenotype (group 1). Only one patient had some features suggestive of Angelman syndrome, but was considered to be a
result of deleted (15)(q12) in the chromosome 15 homologue. Additional copies within D15S11 through GABRB3 (15q11.2-13) resulted
in an abnormal phenotype which involved mental and developmental delay but was different from the classical phenotype of PW/AS
(groups 2, 3). Signs of autistic behavior did occur in each group. FISH combined with microsatellite analyses showed that
the marker was often of maternal origin in de novo cases (n = 12, 86%), or inherited from the mother in only one familial case. Down-inv dup(15) was mentioned in two cases. Unusual
features including diaphragmatic eventration, hyperlaxity of joints, arachnodactyly, brain atrophy, epilepsy (particularly
infantile spasm), ataxia, genital abnormalities, and cleft lip/palate were noted in those patients. This observation expands
the range of phenotypic expression associated with this relatively common ESAC.
Conclusion Marked phenotypic diversities exist in children with inv dup(15), dependent upon the size or genetic composition of the markers,
degree of mosaicism, parental origin and familial occurrence or not. Patients with a larger inv dup(15) marker chromosome
including the PW/ASCR may have a higher risk of abnormalities, but not the typical Prade-Willi/Angelman syndrome phenotype.
Received: 11 February 1997 and in revised form: 20 May 1997 / Accepted: 20 May 1997 相似文献
44.
Antisense RNA-mediated reduction of p53 induces malignant phenotype in nontumorigenic rat urothelial cells 总被引:2,自引:1,他引:2
p53 mutation is commonly associated with high-grade, high-stage human
urothelial carcinomas. Recent studies suggest that p53 mutation in low-
grade, low-stage bladder carcinomas may be correlated with the progression
of the disease. In the present study, we used antisense RNA methodology in
vitro to evaluate the significance of the loss of p53 function at an early
stage of urinary bladder carcinogenesis. An immortalized nontumorigenic rat
urothelial cell line (MYP3) that strongly expresses wild-type (WT) p53 was
transfected with a plasmid (pcDL-SR alpha-296) containing a rat WT p53 cDNA
in antisense orientation. The transfection resulted in a significant
reduction in p53 mRNA expression and protein synthesis, in stimulation of
anchorage- dependent growth, and in acquisition of anchorage-independent
growth potential. Three such clones, when tested in athymic nude mice, all
formed muscle-invasive, high-grade transitional cell carcinomas at s.c.
injection sites. When cells were inoculated into an orthotopic site
(urinary bladder), one of two antisense transfectants tested formed bulky
tumors in the bladder in all seven nude mice and metastases to lungs in
three of the seven mice. Analysis of these cells revealed a decrease in the
expression of p21 (WAF1, sdi1, or CIP1) and retinoblastoma (Rb) gene
product. Phosphorylation of Rb protein was not inhibited when the cells
were starved. No significant difference was observed in the expression of
p16 protein. In cell cycle analysis, all antisense transfectants tested
escaped from G1 arrest by starvation. Furthermore, secretion of interleukin
(IL)-6 into culture medium was increased significantly. Treatment with
anti-IL-6 antibody suppressed anchorage-dependent growth. This study
directly demonstrates that the loss of p53 function at an early stage of
urothelial carcinogenesis may result in acquisition of a malignant
phenotype by regulating IL-6 production as well as cell cycle related
genes.
相似文献
45.
OBJECTIVE: Based on a study of Concha Ostreae, to provide some reference for the rational approach to leaching mineral drugs. METHOD: Taking the change rates of compatible leaching and value of A as targets, the compatible leaching effect of Concha Ostreae with Radix et Rhizoma Rhei Praeparata, Radix Scutellariae, Pollen Typhae and Fructus Aurantii lmmaturus was studied. RESULT: If Concha Ostreae and the above cited medicinal herbs are decocted together, the yield of extract may be reduced to a certain extent, but the target composition of Radix et Rhizoma Rhei Praeparata and Fructus Aurantii lmmaturus remains intact, only the content of Radix Scutellariae baicalin may be influenced. CONCLUSION: The relationship of technology with preparation must be taken into consideration when making choice of the proper way to leach Concha Ostreae. 相似文献
46.
47.
Psychometric evaluation of the Taiwan version of the Disability of the Arm, Shoulder, and Hand (DASH) questionnaire. 总被引:2,自引:0,他引:2
BACKGROUND AND PURPOSE: To adapt the Taiwan version of the Disability of the Arm, Shoulder, and Hand (DASH) questionnaire and evaluate its psychometric properties. METHODS: The DASH questionnaire was adapted through the process of translation, back-translation, and expert review. Eighty two subjects with upper extremity disorders were recruited in a medical center and 46 of these patients could be followed up to assess retest reliability in less than 10 days. Cronbach alpha and intraclass correlation coefficient were used to evaluate the internal consistency and test-retest reliability. Principal axis factor analysis was performed to assess the factor-construct validity, while concurrent validity was tested with the Medical Outcomes Study Short Form-36 (SF-36) Taiwan version questionnaire. RESULTS: The internal consistency of the Taiwan version of the DASH questionnaire was high (Cronbach alpha = 0.96) and the test-retest reliability was satisfactory (intraclass correlation coefficient = 0.9). Principal axis factor analysis confirmed the 1-factor model. The Pearson correlation coefficients of the DASH questionnaire to the SF-36 showed a correlation with physical component summary scores rather than mental component summary scores. Bodily pain, physical function and role-physical scores among the SF-36 subscales were most significantly correlated with DASH disability/symptom scores. CONCLUSION: The Taiwan version of the DASH questionnaire is a valid and reliable measure of health status for patients with upper-extremity disorders. 相似文献
48.
49.
50.
Keratoconjunctivitis sicca (KCS) is a common complication of graft-versus-host disease (GVHD), and may lead to corneal epithelial defect and melting. In contrast, recurrent corneal calcareous degeneration and perforation is rare. A 46-year-old woman developed chronic GVHD after bone marrow transplantation for aplastic anemia. Severe KCS with corneal melting and calcium deposits were noted in the left eye. Penetrating keratoplasty was performed because of corneal perforation, but poor re-epithelialization and calcium deposition recurred. Lamellar keratectomy and amniotic membrane transplantation (AMT) were performed, but acute calcareous degeneration developed with subsequent recurrence of corneal perforation. After regraft, AMT and tarsorrhaphy, the corneal graft remained clear for 3 months. However, breakdown of the corneal epithelium occurred 3 weeks after spontaneous separation of tarsorrhaphy. Six months later, corneal perforation recurred again along with exacerbation of GVHD. Regraft was performed, but the patient refused tarsorrhaphy and AMT. Poor re-epithelialization persisted after regraft. Corneal melting with impending corneal perforation ensued. Further corneal surgery was refused and the patient chose to undergo evisceration. This case demonstrates that the ocular complications of GVHD may be severe enough to lead to corneal perforation and calcareous degeneration that is recalcitrant to medical and surgical treatment. 相似文献