全文获取类型
收费全文 | 3324篇 |
免费 | 249篇 |
国内免费 | 27篇 |
专业分类
耳鼻咽喉 | 14篇 |
儿科学 | 156篇 |
妇产科学 | 83篇 |
基础医学 | 376篇 |
口腔科学 | 123篇 |
临床医学 | 266篇 |
内科学 | 713篇 |
皮肤病学 | 39篇 |
神经病学 | 235篇 |
特种医学 | 143篇 |
外科学 | 512篇 |
综合类 | 190篇 |
一般理论 | 2篇 |
预防医学 | 223篇 |
眼科学 | 136篇 |
药学 | 121篇 |
中国医学 | 9篇 |
肿瘤学 | 259篇 |
出版年
2023年 | 23篇 |
2022年 | 25篇 |
2021年 | 77篇 |
2020年 | 57篇 |
2019年 | 69篇 |
2018年 | 78篇 |
2017年 | 49篇 |
2016年 | 62篇 |
2015年 | 108篇 |
2014年 | 126篇 |
2013年 | 113篇 |
2012年 | 192篇 |
2011年 | 207篇 |
2010年 | 134篇 |
2009年 | 116篇 |
2008年 | 177篇 |
2007年 | 184篇 |
2006年 | 201篇 |
2005年 | 151篇 |
2004年 | 165篇 |
2003年 | 190篇 |
2002年 | 123篇 |
2001年 | 121篇 |
2000年 | 112篇 |
1999年 | 83篇 |
1998年 | 66篇 |
1997年 | 44篇 |
1996年 | 45篇 |
1995年 | 20篇 |
1994年 | 33篇 |
1993年 | 19篇 |
1992年 | 34篇 |
1991年 | 36篇 |
1990年 | 37篇 |
1989年 | 32篇 |
1988年 | 34篇 |
1987年 | 32篇 |
1986年 | 35篇 |
1985年 | 41篇 |
1984年 | 29篇 |
1983年 | 15篇 |
1982年 | 16篇 |
1981年 | 11篇 |
1980年 | 11篇 |
1979年 | 8篇 |
1978年 | 6篇 |
1977年 | 10篇 |
1976年 | 8篇 |
1975年 | 10篇 |
1971年 | 5篇 |
排序方式: 共有3600条查询结果,搜索用时 31 毫秒
21.
22.
Summary Human leukocyte interferon produced in primary cultures of buffy coat cells and human fibroblast interferon from cultures of the FS-4 foreskin cell strain were subjected to isoelectric focusing in polyacrylamide gels. Leukocyte interferon could be resolved into three major components (pI 5.5, 6.2 and 6.6, respectively) and one minor component (pI 7.0). Fibroblast interferon activity focused in a broad pH range of 6.8–7.8.The isoelectrically distinct subspecies of human leukocyte interferon were isolated and compared as to their antigenic nature, heterospecific antiviral activity in cultures of bovine cells, and apparent molecular weights upon electrophoresis in sodium dodecyl sulfate-polyacrylamide gels (SDS-PAGE). The three major subspecies (pI 5.5, 6.2 and 6.6) were similar in their neutralization by antiserum against whole leukocyte interferon and in their relative heterospecific activities on bovine cells. When analyzed on SDS-PAGE, the component focusing at pH 5.5 migrated to a position corresponding to a molecular weight of 17,500 (Le
f), the component with the pI of 6.6 had its major peak corresponding to a molecular weight of 23,000 (Le
s), while the pI 6.2 component contained a mixture of the two molecular weight species. The minor isoelectric component focusing at pI 7.0 contained interferon with the antigenic specificity of fibroblast (F) interferon. It is concluded that the two major antigenic species of human interferon (Le andF) and two known subspecies of human leukocyte interferon (Le
s andLe
f) can be resolved by isoelectric focusing.With 3 Figures 相似文献
23.
The absence of a B allele in acquired B blood group phenotype confirmed by a DNA based genotyping method.
下载免费PDF全文
![点击此处可从《Journal of clinical pathology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
A case of an 87 year old woman with carcinomatous sigmoid colon, found to be of group A1 with acquired B status, is reported. The acquired B phenotype was confirmed by the absence of a B allele in the patient using denaturing gradient gel electrophoresis of a DNA fragment amplified from the ABO locus by the polymerase chain reaction. 相似文献
24.
Mikko?PS?AresEmail author Maria?Stollenwerk Anneli?Olsson Bengt?Kallin Stefan?Jovinge Jan?Nilsson 《BMC immunology》2002,3(1):13
Background
Inflammation and immune responses are considered to be very important in the pathogenesis of atherosclerosis. Lipid accumulation in macrophages of the arterial intima is a characteristic feature of atherosclerosis which can influence the inflammatory potential of macrophages. We studied the effects of lipid loading on the regulation of TNF expression in human monocyte-derived macrophages. 相似文献25.
26.
BACKGROUND: Seasonal variations in suicide deaths and attempted suicides have been reported for many countries. Recent research has suggested that seasonal patterns of suicide deaths have diminished considerably. The seasonality pattern between attempts and completed ones are not the same. This paper is the first one to examine seasonal variation between suicide deaths and attempts simultaneously. METHOD: Census and Statistics Department and the Hospital Authority provided mortality and morbidity data on suicides for the period 1997-2001 in Hong Kong SAR, respectively. Seasonal patterns of suicide deaths and attempts were examined by a harmonic analysis and a non-parametric chi-square test. RESULTS: A significant seasonal variation was detected in suicide attempts with a markedly bi-seasonal pattern was found amongst females with a peak in May and October; only a cyclic pattern was observed for males with a peak in summer. The female attempters who used non-violent suicide methods contributed to the second peak in October. On the other hand, there was no evidence of significant differences in the seasonal distribution among the suicide deaths for males and females. Only a mild pattern was found amongst females involving in violent suicide deaths, while others can be treated as a random event and no significantly pattern was observed in our study. Overall, a significant difference in seasonal variation existed between suicide deaths and attempts (p-value<0.01). CONCLUSIONS: This study reinforces the findings that seasonal variation in suicide appears to be diminishing. Also, suicide attempters and completed suicides in Hong Kong seem to arise from two non-identical but overlapping groups in the community. 相似文献
27.
K.K.W. To C.C.Y. Yip C.Y.W. Lai C.K.H. Wong D.T.Y. Ho P.K.P. Pang A.C.K. Ng K.-H. Leung R.W.S. Poon K.-H. Chan V.C.C. Cheng I.F.N. Hung K.-Y. Yuen 《Clinical microbiology and infection》2019,25(3):372-378
Objectives
Automated point-of-care molecular assays have greatly shortened the turnaround time of respiratory virus testing. One of the major bottlenecks now lies at the specimen collection step, especially in a busy clinical setting. Saliva is a convenient specimen type that can be provided easily by adult patients. This study assessed the diagnostic validity, specimen collection time and cost associated with the use of saliva.Methods
This was a prospective diagnostic validity study comparing the detection rate of respiratory viruses between saliva and nasopharyngeal aspirate (NPA) among adult hospitalized patients using Xpert® Xpress Flu/RSV. The cost and time associated with the collection of saliva and nasopharyngeal specimens were also estimated.Results
Between July and October 2017, 214 patients were recruited. The overall agreement between saliva and NPA was 93.3% (196/210, κ 0.851, 95% CI 0.776–0.926). There was no significant difference in the detection rate of respiratory viruses between saliva and NPA (32.9% (69/210) versus 35.7% (75/210); p 0.146). The overall sensitivity and specificity were 90.8% (81.9%–96.2%) and 100% (97.3%–100%), respectively, for saliva, and were 96.1% (88.9%–99.2%) and 98.5% (94.7%–99.8%), respectively, for NPA. The time and cost associated with the collection of saliva were 2.26-fold and 2.59-fold lower, respectively, than those of NPA.Conclusions
Saliva specimens have high sensitivity and specificity in the detection of respiratory viruses by an automated multiplex Clinical Laboratory Improvement Amendments-waived point-of-care molecular assay when compared with those of NPA. The use of saliva also reduces the time and cost associated with specimen collection. 相似文献28.
Mahadevaiah SK; Odorisio T; Elliott DJ; Rattigan A; Szot M; Laval SH; Washburn LL; McCarrey JR; Cattanach BM; Lovell-Badge R; Burgoyne PS 《Human molecular genetics》1998,7(4):715-727
An RNA-binding motif (RBM) gene family has been identified on the human Y
chromosome that maps to the same deletion interval as the 'azoospermia
factor' (AZF). We have identified the homologous gene family (Rbm) on the
mouse Y with a view to investigating the proposal that this gene family
plays a role in spermatogenesis. At least 25 and probably >50 copies of
Rbm are present on the mouse Y chromosome short arm located between Sry and
the centromere. As in the human, a role in spermatogenesis is indicated by
a germ cell-specific pattern of expression in the testis, but there are
distinct differences in the pattern of expression between the two species.
Mice carrying the deletion Yd1, that maps to the proximal Y short arm, are
female due to a position effect resulting in non-expression of Sry ;
sex-reversing such mice with an Sry transgene produces males with a high
incidence of abnormal sperm, making this the third deletion interval on the
mouse Y that affects some aspect of spermatogenesis. Most of the copies of
Rbm map to this deletion interval, and the Yd1males have markedly reduced
Rbm expression, suggesting that RBM deficiency may be responsible for, or
contribute to, the abnormal sperm development. In man, deletion of the
functional copies of RBM is associated with meiotic arrest rather than
sperm anomalies; however, the different effects of deletion are consistent
with the differences in expression between the two species.
相似文献
29.
Distribution of mutations in the PEX gene in families with X-linked hypophosphataemic rickets (HYP) 总被引:8,自引:0,他引:8
Rowe PS; Oudet CL; Francis F; Sinding C; Pannetier S; Econs MJ; Strom TM; Meitinger T; Garabedian M; David A; Macher MA; Questiaux E; Popowska E; Pronicka E; Read AP; Mokrzycki A; Glorieux FH; Drezner MK; Hanauer A; Lehrach H; Goulding JN; O'Riordan JL 《Human molecular genetics》1997,6(4):539-549
Mutations in the PEX gene at Xp22.1 (phosphate-regulating gene with
homologies to endopeptidases, on the X-chromosome), are responsible for
X-linked hypophosphataemic rickets (HYP). Homology of PEX to the M13 family
of Zn2+ metallopeptidases which include neprilysin (NEP) as prototype, has
raised important questions regarding PEX function at the molecular level.
The aim of this study was to analyse 99 HYP families for PEX gene
mutations, and to correlate predicted changes in the protein structure with
Zn2+ metallopeptidase gene function. Primers flanking 22 characterised
exons were used to amplify DNA by PCR, and SSCP was then used to screen for
mutations. Deletions, insertions, nonsense mutations, stop codons and
splice mutations occurred in 83% of families screened for in all 22 exons,
and 51% of a separate set of families screened in 17 PEX gene exons.
Missense mutations in four regions of the gene were informative regarding
function, with one mutation in the Zn2+-binding site predicted to alter
substrate enzyme interaction and catalysis. Computer analysis of the
remaining mutations predicted changes in secondary structure,
N-glycosylation, protein phosphorylation and catalytic site molecular
structure. The wide range of mutations that align with regions required for
protease activity in NEP suggests that PEX also functions as a protease,
and may act by processing factor(s) involved in bone mineral metabolism.
相似文献
30.
We have investigated the effects of intravitreal sciatic nerve (SN) and/or optic nerve (ON) grafts on the survival and the axonal regeneration of retinal ganglion cells (RGCs). Following transection of the ON, approximately 40% RGCs survived at 7 days post-axotomy (dpa). Results showed that the intravitreal ON graft significantly promoted the survival of RGCs at 7 dpa (39,063 vs 28,246). Intravitreal SN graft, however, did not rescue axotomized RGCs at 5, 7 or 14 dpa. Axotomized RGCs could be induced to regenerate axons along a segment of SN graft attached to the proximal stump of ON. On average, 608 axotomized RGCs were induced to regenerate axons along the attached SN graft. The presence of intravitreal SN graft promoted about 100% increase in the number of regenerating RGCs (1,227) relative to the control groups. The intravitreal ON graft, surprisingly, also induced about 100% more regenerating RGCs (1220) than in the control group. When SN and ON grafts were co-transplanted into the vitreous, about 200% more regenerating RGCs (1916) were observed than in the control group. These findings illustrated that the intravitreal ON graft rescued axotomized RGCs and enhanced the regeneration of retinal axons. This is the first report to show that ON promotes RGC axonal regeneration. The intravitreal SN graft did not rescue RGCs but promoted axonal regeneration. The differential effects of intravitreal ON and SN grafts on the survival and the RGC regeneration suggest that these might be two independently operating events. 相似文献