全文获取类型
收费全文 | 1432篇 |
免费 | 88篇 |
国内免费 | 11篇 |
专业分类
耳鼻咽喉 | 15篇 |
儿科学 | 107篇 |
妇产科学 | 20篇 |
基础医学 | 226篇 |
口腔科学 | 30篇 |
临床医学 | 157篇 |
内科学 | 254篇 |
皮肤病学 | 24篇 |
神经病学 | 139篇 |
特种医学 | 321篇 |
外科学 | 80篇 |
综合类 | 13篇 |
预防医学 | 35篇 |
眼科学 | 7篇 |
药学 | 40篇 |
肿瘤学 | 63篇 |
出版年
2021年 | 12篇 |
2020年 | 4篇 |
2019年 | 8篇 |
2018年 | 18篇 |
2017年 | 10篇 |
2016年 | 21篇 |
2015年 | 29篇 |
2014年 | 33篇 |
2013年 | 42篇 |
2012年 | 26篇 |
2011年 | 35篇 |
2010年 | 37篇 |
2009年 | 38篇 |
2008年 | 39篇 |
2007年 | 53篇 |
2006年 | 36篇 |
2005年 | 33篇 |
2004年 | 32篇 |
2003年 | 19篇 |
2002年 | 18篇 |
2001年 | 21篇 |
2000年 | 15篇 |
1999年 | 32篇 |
1998年 | 97篇 |
1997年 | 71篇 |
1996年 | 83篇 |
1995年 | 55篇 |
1994年 | 56篇 |
1993年 | 62篇 |
1992年 | 24篇 |
1991年 | 15篇 |
1990年 | 19篇 |
1989年 | 46篇 |
1988年 | 35篇 |
1987年 | 46篇 |
1986年 | 32篇 |
1985年 | 32篇 |
1984年 | 30篇 |
1983年 | 21篇 |
1982年 | 23篇 |
1981年 | 26篇 |
1980年 | 28篇 |
1979年 | 9篇 |
1978年 | 18篇 |
1977年 | 19篇 |
1976年 | 22篇 |
1975年 | 18篇 |
1970年 | 9篇 |
1969年 | 4篇 |
1966年 | 2篇 |
排序方式: 共有1531条查询结果,搜索用时 31 毫秒
21.
R S Hikida R S Staron F C Hagerman M Leonardi R Gilders J Falkel T Murray K Appell 《Clinical physiology》1991,11(1):51-59
The significance of the absolute elevations of serum creatine kinase (CK) levels after intense exercise and injuries was studied by measuring CK activities from seven healthy active males during a 2-week period, with a muscle biopsy taken between the first and second week. Most of the subjects (three lifters and two runners) carried on their normal exercise activities, while two lifters stopped training during the 2 weeks. The weight of the biopsy, number of fibres, percentage of fibre types, and cross-sectional areas of the muscle fibres were measured. The CK levels of the non-active subjects and runners remained consistently low during the control week, whereas those of the lifters were usually 500% greater than those of the other two groups, and fluctuated with the intensity of their workouts. A muscle biopsy, having a mean weight of 71.3 mg and containing 1800 fibres, increased the CK values by approximately 100 units litre-1 (U l-1) in most of the subjects. One runner injured his right hamstring muscles 2 days prior to the biopsy, and his CK values rose from 50 to 4400 U l-1. The increases in CK after the biopsy were not related to fibre type, activity, weight of the biopsy, or number or size of fibres removed. These results indicate that: (1) CK values are consistently lower in normal subjects and runners than in lifters. (2) Weight training results in chronic elevations of CK. (3) Compared to a muscle biopsy, muscular injury dramatically increases CK levels. (4) Elevation of serum CK is observed as early as 1 h after an intense weight-lifting session.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
22.
Mutation spectrum and genotype-phenotype analyses in Cowden disease and Bannayan-Zonana syndrome, two hamartoma syndromes with germline PTEN mutation 总被引:22,自引:1,他引:22
Marsh DJ; Coulon V; Lunetta KL; Rocca-Serra P; Dahia PL; Zheng Z; Liaw D; Caron S; Duboue B; Lin AY; Richardson AL; Bonnetblanc JM; Bressieux JM; Cabarrot-Moreau A; Chompret A; Demange L; Eeles RA; Yahanda AM; Fearon ER; Fricker JP; Gorlin RJ; Hodgson SV; Huson S; Lacombe D; Eng C 《Human molecular genetics》1998,7(3):507-515
The tumour suppressor gene PTEN , which maps to 10q23.3 and encodes a 403
amino acid dual specificity phosphatase (protein tyrosine phosphatase;
PTPase), was shown recently to play a broad role in human malignancy.
Somatic PTEN deletions and mutations were observed in sporadic breast,
brain, prostate and kidney cancer cell lines and in several primary tumours
such as endometrial carcinomas, malignant melanoma and thyroid tumours. In
addition, PTEN was identified as the susceptibility gene for two hamartoma
syndromes: Cowden disease (CD; MIM 158350) and Bannayan-Zonana (BZS) or
Ruvalcaba-Riley-Smith syndrome (MIM 153480). Constitutive DNA from 37 CD
families and seven BZS families was screened for germline PTEN mutations.
PTEN mutations were identified in 30 of 37 (81%) CD families, including
missense and nonsense point mutations, deletions, insertions, a
deletion/insertion and splice site mutations. These mutations were
scattered over the entire length of PTEN , with the exception of the first,
fourth and last exons. A 'hot spot' for PTEN mutation in CD was identified
in exon 5 that contains the PTPase core motif, with 13 of 30 (43%) CD
mutations identified in this exon. Seven of 30 (23%) were within the core
motif, the majority (five of seven) of which were missense mutations,
possibly pointing to the functional significance of this region. Germline
PTEN mutations were identified in four of seven (57%) BZS families studied.
Interestingly, none of these mutations was observed in the PTPase core
motif. It is also worthy of note that a single nonsense point mutation,
R233X, was observed in the germline DNA from two unrelated CD families and
one BZS family. Genotype-phenotype studies were not performed on this small
group of BZS families. However, genotype-phenotype analysis inthe group of
CD families revealed two possible associations worthy of follow-up in
independent analyses. The first was an association noted in the group of CD
families with breast disease. A correlation was observed between the
presence/absence of a PTEN mutation and the type of breast involvement
(unaffected versus benign versus malignant). Specifically and more
directly, an association was also observed between the presence of a PTEN
mutation and malignant breast disease. Secondly, there appeared to be an
interdependent association between mutations upstream and within the PTPase
core motif, the core motif containing the majority of missense mutations,
and the involvement of all major organ systems (central nervous system,
thyroid, breast, skin and gastrointestinal tract). However, these
observations would need to be confirmed by studying a larger number of CD
families.
相似文献
23.
24.
ATRX encodes a novel member of the SNF2 family of proteins: mutations point to a common mechanism underlying the ATR-X syndrome 总被引:11,自引:3,他引:11
Picketts DJ; Higgs DR; Bachoo S; Blake DJ; Quarrell OW; Gibbons RJ 《Human molecular genetics》1996,5(12):1899-1907
It was shown recently that mutations of the ATRX gene give rise to a
severe, X-linked form of syndromal mental retardation associated with alpha
thalassaemia (ATR-X syndrome). In this study, we have characterised the
full-length cDNA and predicted structure of the ATRX protein. Comparative
analysis shows that it is an entirely new member of the SNF2 subgroup of a
superfamily of proteins with similar ATPase and helicase domains. ATRX
probably acts as a regulator of gene expression. Definition of its genomic
structure enabled us to identify four novel splicing defects by screening
52 affected individuals. Correlation between these and previously
identified mutations with variations in the ATR-X phenotype provides
insights into the pathophysiology of this disease and the normal role of
the ATRX protein in vivo.
相似文献
25.
26.
R J Hagerman K Van Housen A C Smith L McGavran 《American journal of medical genetics》1984,17(1):111-121
Eleven cytogenetically documented patients with the fragile X syndrome were evaluated for hyperextensibility of the finger joints and the presence of other manifestations of connective tissue dysfunction. All of the patients had hyperextensibility of several finger joints and many had features such as flat feet, highly arched palate and the ability to voluntarily dislocate finger joints. These traits, particularly hyperextensibility of the joints, are a useful aid in the clinical diagnosis of the fragile X syndrome. 相似文献
27.
Evolutionary silencing of the human elastase I gene (ELA1) 总被引:6,自引:0,他引:6
28.
Huisman JA; Paulussen RJ; Geurts TB; Odink J; Rekers H 《Human reproduction (Oxford, England)》1997,12(1):34-38
The objective was to demonstrate bioequivalence between s.c. and i.m.
administration of Humegon (FSH/LH ratio 1:1) and Normegon (FSH/LH ratio
3:1). In two randomized, single-centre, cross-over studies, 18 healthy
volunteers on each formulation were assigned to one of the two
administration sequences. Subjects were given single doses of one of the
above gonadotrophins after endogenous gonadotrophin production had first
been suppressed using high-dose oral contraceptive. Subsequently, rate
(Cmax, tmax) and extent (AUC) of absorption of follicle stimulating hormone
(FSH) and luteinizing hormone (LH) were determined for 14 days. For Cmax
and AUC, analysis of variance (ANOVA) was performed on log-transformed data
and for tmax ANOVA was performed on ranks. Intramuscular and s.c.
injections of Humegon were bioequivalent with respect to the main
pharmacokinetic parameters, being AUC and Cmax of FSH absorption.
Intramuscular and s.c. injections of Normegon were bioequivalent with
respect to the AUC of FSH and not bioequivalent with respect to the Cmax of
FSH. For tmax of FSH as well as for most LH variables of both preparations,
bioequivalence could not be proven due to the high intra- and
interindividual variability and/or concentrations being close to the
detection limit. Thus, the main pharmacokinetic FSH variables after i.m.
and s.c. administration of Humegon and Normegon were bioequivalent.
相似文献
29.
Alessio HM Hagerman AE Nagy S Philip B Byrnes RN Woodward JL Callahan P Wiley RL 《Physiology & behavior》2005,84(1):65-72
Voluntary and forced exercise decrease morbidity and mortality in laboratory animals. Caloric restriction has similar effects on health and unique benefits on life span. Nonetheless, in most experiments, animals do not have access to physical activity and are fed ad libitum (AL). We hypothesized that with regular access to either unlimited running wheel exercise (EX) or limited physical activity (PA), key biomarkers of health would be enhanced enough to counter some consequences of a sedentary AL lifestyle. This 16-month study compared body weight, tumor number and size, tissue lesions, oxidative stress, and reactive stress in (1) sedentary animals with no access to physical activity (SED); (2) animals with access to hour-long, twice weekly activity in a large box (PA); and (3) animals with access every other day to a running wheel (EX). At the end of the study, EX body weight was 8-9% lower than PA and SED. In addition, EX had no kidney lesions versus 50% in PA and SED, and had smaller tumor size (10+/-2 vs. 14+/-4 and 30+/-4 mm). Exhaustive exercise lowered glutathione/oxidized glutathione ratio in EX and PA, but in SED, the ratio was depressed even in resting animals. In all treatments, prolactin (PRL) levels were lower in resting animals than in acutely exercised animals. In conclusion, EX had the most favorable health biomarkers while SED had the least. PA did not confer gross health benefits different than the SED group, but was biochemically more similar to EX animals. 相似文献
30.