全文获取类型
收费全文 | 1500篇 |
免费 | 177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 | 201篇 |
口腔科学 | 90篇 |
临床医学 | 159篇 |
内科学 | 283篇 |
皮肤病学 | 50篇 |
神经病学 | 31篇 |
特种医学 | 173篇 |
外科学 | 223篇 |
综合类 | 38篇 |
预防医学 | 95篇 |
眼科学 | 40篇 |
药学 | 53篇 |
中国医学 | 2篇 |
肿瘤学 | 94篇 |
出版年
2023年 | 14篇 |
2022年 | 10篇 |
2021年 | 13篇 |
2020年 | 15篇 |
2019年 | 8篇 |
2018年 | 44篇 |
2017年 | 46篇 |
2016年 | 41篇 |
2015年 | 60篇 |
2014年 | 76篇 |
2013年 | 106篇 |
2012年 | 47篇 |
2011年 | 29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 | 29篇 |
2003年 | 13篇 |
2002年 | 19篇 |
2001年 | 16篇 |
2000年 | 9篇 |
1999年 | 24篇 |
1998年 | 101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 | 14篇 |
1989年 | 31篇 |
1988年 | 29篇 |
1987年 | 28篇 |
1986年 | 27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 | 7篇 |
1977年 | 9篇 |
1976年 | 13篇 |
1975年 | 10篇 |
1966年 | 1篇 |
排序方式: 共有1705条查询结果,搜索用时 15 毫秒
61.
In recent reports we described novel hybridization patterns (HP) corresponding to 22 potentially new HLA-B locus alleles in a panel of 547 subjects studied by PCR-SSOP. Three of them correspond to new subtypes of B35. To confirm the hybridization results we have isolated DNA from PBL and performed PCR, DNA cloning and nucleotide sequencing. One of the alleles, locally called B-3505v was found in three individuals: two Hispanic, one Caucasoid. It differs from B*3505 by 3 nucleotide substitutions that lead to changes in residues 94 (Ile > Thr), 95 (Ile > Leu) and 103 (Val > Leu). B-3505v differs from B*3501 in residues 97 and 103. Another allele called B-3508v, was found in 7 individuals, (6 of 122 Toba Indians, 1 of 18 Pilaga Indians). It differs from B*3509 in two silent nucleotide substitutions (codons 135 and 138) and in one substitution in residue 156 (Arg > Leu). The new allele has a hybrid sequence between B* 3508 and B*4801. A third subtype, locally called B-3504v, observed in two Hispanic individuals, is identical to B*3512. B*3512 differs from B*3504 by 3 nucleotides and one amino acid. Substitutions in residue 95 contribute to the structure of specificity pocket F, 97 to C and E, and 156 to pockets D and E. Therefore it is possible that some of the new alleles may have different peptide binding profiles. Since differences in residue 156 have been shown to affect allorecognition and mediate GvHD, identification of such variants may have important implications in transplantation and perhaps in studies of immune responses to peptides and pathogens. 相似文献
62.
63.
H4 acetylation, XIST RNA and replication timing are coincident and define x;autosome boundaries in two abnormal X chromosomes 总被引:2,自引:1,他引:2
The inactive X (Xi) differs from its active homologue (Xa) in a number of
ways, including increased methylation of CpG islands, replication late in S
phase, underacetylation of histone H4 and association with XIST RNA. Global
changes in DNA methylation occur relatively late in development, but the
other properties all change during or shortly after the establishment of Xi
and may play a role in the mechanism by which an inactive chromatin
conformation spreads across most of the chromosome. In the present report,
we use two human X;autosome translocation chromosomes to study the
spreading of inactive X chromatin across X;autosome boundaries. In one of
these chromosomes, t(X;6), Xp distal to p11.2 is replaced by 6p21.1-6pter
and, in the other, ins(X;16), a small fragment derived from 16p13 is
inserted into the distal third of Xq. In lymphoid cells from patients
carrying these translocations in an unbalanced form, Xi was shown by HUMARA
assay to be derived exclusively [t(X:6)] or predominantly [ins (X;16)] from
the derived X chromosome. We used a combination of immunolabelling and
RNA/DNA fluorescence in situ hybridization to define the distribution of
XIST RNA, deacetylated H4 and late-replicating DNA across the two derived X
chromosomes in inactive form. Within the limits of the cytogenetic
techniques employed, the results show complete coincidence of these three
parameters, with all three being excluded from the autosomal component of
the derived X chromosome.
相似文献
64.
Joyce JPA Bierbooms Inge MB Bongers Hans AM van Oers 《BMC medical informatics and decision making》2011,11(1):1
Background
Despite large-scale investments in mental health care in the community since the 1990 s, a trend towards reinstitutionalization has been visible since 2002. Since many mental health care providers regard this as an undesirable trend, the question arises: In the coming 5 years, what types of residence should be organized for people with mental health problems? The purpose of this article is to provide mental health care providers, public housing corporations, and local government with guidelines for planning organizational strategy concerning types of residence for people with mental health problems. 相似文献65.
AM Waryah A Rehman ZM Ahmed Z-H Bashir SY Khan AU Zafar S Riazuddin TB Friedman S Riazuddin 《Clinical genetics》2009,76(3):270-275
Autosomal recessive nonsyndromic hearing impairment (ARNSHI) segregating in three unrelated, large consanguineous Pakistani families (PKDF528, PKDF859 and PKDF326) is linked to markers on chromosome 12q14.2-q15. This novel locus is designated DFNB74 . Maximum two-point limit of detection (LOD) scores of 5.6, 5.7 and 2.6 were estimated for markers D 12 S 313, D 12 S 83 and D 12 S 75 at θ = 0 for recessive deafness segregating in these three families. Haplotype analyses identified a critical linkage interval of 5.35 cM (5.36 Mb) defined by D 12 S 329 at 74.58 cM and D 12 S 313 at 79.93 cM. DFNB74 is the second ARNSHI locus mapped to chromosome 12, but the physical intervals do not overlap with one another. A locus contributing to the early onset, rapidly progressing hearing loss of A/J mice ( ahl4 , age-related hearing loss 4) was reported to map to chromosome 10 in a region of conserved synteny to DFNB74 , suggesting that ahl4 and DFNB74 may be due to mutations of the same gene in these two species. 相似文献
66.
67.
68.
69.
70.
Anderson RA; Wallace AM; Kicman AT; Wu FC 《Human reproduction (Oxford, England)》1997,12(8):1657-1662
Administration of supraphysiological doses of testosterone to normal men
causes inhibition of spermatogenesis, but while most become azoospermic,
30-55% maintain a low rate of spermatogenesis. We have investigated whether
there are differences in endogenous androgen production, of testicular and
adrenal origin, which may be related to the degree of suppression of
spermatogenesis. Thirty-three healthy Caucasian men were given weekly i.m.
injections of 200 mg testosterone oenanthate (TE), 18 became azoospermic,
while 15 remained oligozoospermic. Urinary excretion of epitestosterone, a
specific testicular product, was reduced to <10% of pretreatment values,
with no differences between the groups. Similar results were obtained for
other markers of testicular steroidogenesis. Urinary and plasma adrenal
androgens were also reduced during TE treatment: a statistically
significant decrease in both (P < 0.001 and P < 0.05 respectively)
was seen in the azoospermic but not oligozoospermic responders. These
results suggest that testicular steroidogenesis is decreased to <10% by
the administration of supraphysiological doses of exogenous testosterone.
Differences in the degree of ongoing steroidogenesis in the testis do not
appear to account for incomplete suppression of spermatogenesis, thus
differences in androgen metabolism may underlie this heterogeneous
response. A small but significant reduction in secretion of adrenal
androgens was also detectable, the relevance of which is unclear.
相似文献