全文获取类型
收费全文 | 966篇 |
免费 | 44篇 |
国内免费 | 1篇 |
专业分类
耳鼻咽喉 | 6篇 |
儿科学 | 61篇 |
妇产科学 | 24篇 |
基础医学 | 125篇 |
口腔科学 | 19篇 |
临床医学 | 93篇 |
内科学 | 198篇 |
皮肤病学 | 8篇 |
神经病学 | 71篇 |
特种医学 | 158篇 |
外科学 | 83篇 |
综合类 | 7篇 |
预防医学 | 66篇 |
眼科学 | 11篇 |
药学 | 46篇 |
肿瘤学 | 35篇 |
出版年
2021年 | 4篇 |
2019年 | 6篇 |
2018年 | 10篇 |
2017年 | 8篇 |
2016年 | 8篇 |
2015年 | 12篇 |
2014年 | 22篇 |
2013年 | 28篇 |
2012年 | 18篇 |
2011年 | 32篇 |
2010年 | 35篇 |
2009年 | 26篇 |
2008年 | 22篇 |
2007年 | 23篇 |
2006年 | 32篇 |
2005年 | 34篇 |
2004年 | 26篇 |
2003年 | 28篇 |
2002年 | 29篇 |
2001年 | 20篇 |
2000年 | 27篇 |
1999年 | 33篇 |
1998年 | 36篇 |
1997年 | 32篇 |
1996年 | 34篇 |
1995年 | 30篇 |
1994年 | 28篇 |
1993年 | 24篇 |
1992年 | 12篇 |
1991年 | 15篇 |
1990年 | 27篇 |
1989年 | 21篇 |
1988年 | 27篇 |
1987年 | 26篇 |
1986年 | 16篇 |
1985年 | 25篇 |
1984年 | 21篇 |
1983年 | 14篇 |
1982年 | 23篇 |
1981年 | 13篇 |
1980年 | 12篇 |
1978年 | 12篇 |
1977年 | 11篇 |
1976年 | 16篇 |
1975年 | 9篇 |
1971年 | 4篇 |
1970年 | 4篇 |
1968年 | 4篇 |
1967年 | 5篇 |
1966年 | 5篇 |
排序方式: 共有1011条查询结果,搜索用时 15 毫秒
1.
2.
Filipin, a complex of polyene antibiotics, forms morphologically distinctive complexes with cholesterol in cell membranes under proper experimental conditions. When applied to non-activated, discoid platelets, filipin-induced lesions (FIL) occurred in rows at the platelet equator, suggesting a specialized membrane organization at the platelets' largest circumference. In some thrombin-activated platelets we observed surface membrane blebbing and release of lipid vesicles that predominantly originated from the plasma membrane proper, but some originated from (unidentified) platelet granules. FIL were initially present in high numbers over the entire bleb, they accumulated later at the neck of blebs, while the released vesicle was free of FIL. Absence of intramembrane protein particles (IMP) from the membranes of blebs and vesicles suggests that released vesicles are essentially without cholesterol and intrinsic membrane proteins and may consist predominantly of phospholipids. Membrane blebbing and vesicle release may represent unmasking and release of procoagulant platelet factor 3 activity. 相似文献
3.
4.
Ralf-Peter Vonberg Sabine Stamm-Balderjahn Sonja Hansen Irina Zuschneid Henning Ruden Michael Behnke Petra Gastmeier 《Infection control and hospital epidemiology》2006,27(10):1123-1127
A systematic search was performed to identify outbreaks of methicillin-resistant Staphylococcus aureus infection and colonization caused by healthcare workers (HCWs). Of 191 outbreaks identified, 11 had strong epidemiological evidence that HCWs were the source. In 3 of these outbreaks, asymptomatic carriers were the cause. The frequent practice of screening asymptomatic HCWs should be reconsidered. 相似文献
5.
Steenbergen EJ; Verhagen OJ; van Leeuwen EF; van den Berg H; von dem Borne AE; van der Schoot CE 《Blood》1995,86(2):692-702
Crosslineage T-cell receptor delta (TCR delta) rearrangements are widely used as tumor markers for the follow up of minimal residual disease in childhood B-precursor acute lymphoblastic leukemia (ALL) by polymerase chain reaction (PCR). The major drawback of this approach is the risk of false-negative results due to clonal evolution. We investigated the stability of V delta 2D delta 3 rearrangements in a group of 56 childhood B-precursor ALL patients by PCR and Southern blot analysis. At the PCR level, V delta 2D delta 3-to-J alpha rearranged subclones (one pathway for secondary TCR delta recombination) were demonstrated in 85.2% of V delta 2D delta 3-positive patients tested, which showed that small subclones are present in the large majority of patients despite apparently monoclonal TCR delta Southern blot patterns. Sequence analysis of V delta 2D delta 3J alpha rearrangements showed a biased J alpha gene usage, with HAPO5 and J alpha F in 26 of 32 and 6 of 32 clones, respectively. Comparison of V delta 2D delta 3 rearrangement status between diagnosis and first relapse showed differences in seven of eight patients studied. In contrast, from first relapse onward, no clonal changes were observed in six patients studied. To investigate the occurrence of crosslineage TCR delta rearrangements in normal B and T cells, fluorescence-activated cell sorter-sorted peripheral blood CD19+/CD3- and CD19-/CD3+ cell populations from three healthy donors were analyzed. V delta 2D delta 3 rearrangements were detected at low frequencies in both B and T cells, which suggests that V delta 2-to-D delta 3 joining also occurs during normal B-cell differentiation. A model for crosslineage TCR delta rearrangements in B-precursor ALL is deduced that explains the observed clonal changes between diagnosis and relapse and is compatible with multistep leukemogenesis of B-precursor ALL. 相似文献
6.
7.
Summary In various primary brain tumours of neuroepithelial tissue recombinant DNA techniques were used to demonstrate changes of the epidermal growth factor receptor gene, which is homologous to the c-erbB oncogene. Twenty-one of 40 grade III/IV tumours, but only 1 of 16 grade I/II tumours were found to contain amplified and/or rearranged c-erbB sequences. This highly significant difference suggest that c-erbB amplification, rearrangement, or both, are important steps in malignant transformation in a subset of patients with neuroepithelial tumours. 相似文献
8.
Analysis of the mechanism of immunodepression following heterologous antigenic stimulation during concurrent infection with Nematospiroides dubius. 总被引:1,自引:0,他引:1 下载免费PDF全文
The suppression of immune responsiveness to heterologous antigenic stimulation during concurrent infection with Nematospiroides dubius was reproduced using soluble antigens derived from adult parasites. Immunosuppression appeared to be selective in that the administration of equivalent quantities of an irrelevant heterogeneous antigen had no immunosuppressive effect, and suppression was transferable using spleen cells from parasite antigen-treated donors. The differential immunomodulatory activity of parasite antigens from a variety of nematode species suggested that a correlation might exist between suppressor activity and chronicity of infection. A role for suppressor T cell activity in the infected host was implicated by the restorative effect of 2'deoxyguanosine treatment on the immune response, and non-specific suppressor cell activity was detected in splenocyte populations from infected mice. It is suggested that a parasite-induced defect in antigen processing led to the induction of suppressor cell activity in the infected host and that this may be one mechanism of parasite survival. The relevance of these observations to vaccination against chronic gastrointestinal nematode infections is discussed. 相似文献
9.
Sequence comparison of human and yeast telomeres identifies structurally distinct subtelomeric domains 总被引:6,自引:2,他引:6
Flint J; Bates GP; Clark K; Dorman A; Willingham D; Roe BA; Micklem G; Higgs DR; Louis EJ 《Human molecular genetics》1997,6(8):1305-1313
We have sequenced and compared DNA from the ends of three human
chromosomes: 4p, 16p and 22q. In all cases the pro-terminal regions are
subdivided by degenerate (TTAGGG)n repeats into distal and proximal sub-
domains with entirely different patterns of homology to other chromosome
ends. The distal regions contain numerous, short (<2 kb) segments of
interrupted homology to many other human telomeric regions. The proximal
regions show much longer (approximately 10-40 kb) uninterrupted homology to
a few chromosome ends. A comparison of all yeast subtelomeric regions
indicates that they too are subdivided by degenerate TTAGGG repeats into
distal and proximal sub-domains with similarly different patterns of
identity to other non-homologous chromosome ends. Sequence comparisons
indicate that the distal and proximal sub-domains do not interact with each
other and that they interact quite differently with the corresponding
regions on other, non- homologous, chromosomes. These findings suggest that
the degenerate TTAGGG repeats identify a previously unrecognized,
evolutionarily conserved boundary between remarkably different subtelomeric
domains.
相似文献
10.
Canfield MC; Tamarappoo BK; Moses AM; Verkman AS; Holtzman EJ 《Human molecular genetics》1997,6(11):1865-1871
Congenital nephrogenic diabetes insipidus (NDI) is a rare disease caused
most often by mutations in the vasopressin V2 receptor (AVPR2). We studied
a family which included a female patient with NDI with symptoms dating from
infancy. The patient responded to large doses of desmopressin (dDAVP) which
decreased urine volume from 10 to 4 I/day. Neither the parents nor the
three sisters were polyuric. The patient was found to be a compound
heterozygote for two novel recessive point mutations in the aquaporin-2
(AQP2) gene: L22V in exon 1 and C181W in exon 3. Residue Cys181 in AQP2 is
the site for inhibition of water permeation by mercurial compounds and is
located near to the NPA motif conserved in all aquaporins. Osmotic water
permeability (Pf) in Xenopus oocytes injected with cRNA encoding C181W-AQP2
was not increased over water control, while expression of L22V cRNA
increased the Pf to approximately 60% of that for wild-type AQP2.
Co-injection of the mutant cRNAs with the wild-type cRNA did not affect the
function of the wild-type AQP2. Immunolocalization of AQP2-transfected CHO
cells showed that the C181W mutant had an endoplasmic reticulum-like
intracellular distribution, whereas L22V and wild-type AQP2 showed endosome
and plasma membrane staining. Water permeability assays showed a high Pf in
cells expressing wild-type and L22V AQP2. This study indicates that AQP2
mutations can confer partially responsive NDI.
相似文献