全文获取类型
收费全文 | 219篇 |
免费 | 10篇 |
国内免费 | 1篇 |
专业分类
230篇 |
出版年
2021年 | 3篇 |
2019年 | 3篇 |
2017年 | 3篇 |
2015年 | 3篇 |
2014年 | 9篇 |
2013年 | 11篇 |
2012年 | 13篇 |
2011年 | 4篇 |
2010年 | 11篇 |
2009年 | 6篇 |
2008年 | 7篇 |
2007年 | 9篇 |
2006年 | 4篇 |
2005年 | 10篇 |
2004年 | 4篇 |
2003年 | 3篇 |
2002年 | 3篇 |
2001年 | 8篇 |
2000年 | 3篇 |
1999年 | 9篇 |
1998年 | 11篇 |
1997年 | 9篇 |
1996年 | 2篇 |
1995年 | 4篇 |
1994年 | 5篇 |
1993年 | 3篇 |
1992年 | 2篇 |
1991年 | 3篇 |
1990年 | 6篇 |
1989年 | 2篇 |
1988年 | 3篇 |
1987年 | 5篇 |
1986年 | 4篇 |
1985年 | 5篇 |
1984年 | 4篇 |
1983年 | 2篇 |
1982年 | 3篇 |
1981年 | 4篇 |
1978年 | 2篇 |
1977年 | 4篇 |
1976年 | 3篇 |
1975年 | 2篇 |
1967年 | 2篇 |
1963年 | 1篇 |
1959年 | 1篇 |
1954年 | 1篇 |
1950年 | 1篇 |
1933年 | 1篇 |
1924年 | 1篇 |
1923年 | 1篇 |
排序方式: 共有230条查询结果,搜索用时 0 毫秒
31.
32.
33.
M. Boel J. Timmermans L. Emmery G. Dralands J. P. Fryns H. Van den Berghe 《Human genetics》1979,51(2):237-240
Summary In this report two brothers with a severe form of Peters' anomaly, i.e., primary dysgenesis mesodermalis of the cornea, are described. The thirddegree consanguinity of the parents is an additional argument for the autosomal recessive inheritance of this condition. 相似文献
34.
Marmoset phylogenetics, conservation perspectives, and evolution of the mtDNA control region 总被引:2,自引:1,他引:2
Tagliaro CH; Schneider MP; Schneider H; Sampaio IC; Stanhope MJ 《Molecular biology and evolution》1997,14(6):674-684
Marmosets (genus Callithrix) are a diverse group of platyrrhine primates
with 13-15 purported taxa, many of them considered endangered.
Morphological analyses constitute most of the basis for recognition of
these forms as distinct taxa. The purpose of this study was to provide a
molecular view, based on mitochondrial control region sequences, of the
evolutionary history of the marmosets, concomitant with a molecular
phylogenetic perspective on species diversity within the group. An
additional purpose was to provide the first comparative examination of a
complete New World monkey control region sequence with those of other
mammals. The phylogenetic analyses provide convincing support for a split
between the Atlantic forest and Amazonian marmosets, with the inclusion of
the pygmy marmoset (Cebuella pygmaea) at the base of the Amazonian clade.
The earliest branch of the Atlantic forest group was C. aurita. In the
Amazonian group, the analyses do not support the recognition of C.
humeralifer and the recently described C mauesi as distinct taxa. They do,
however, support a clear distinction between C. argentata and a strongly
supported mixed clade of C. humeralifer and C. mauesi. In the Atlantic
forest group, the phylogenetic tree suggests mixing between C. penicillata,
C. kuhli, and possibly C. jacchus. Most of the sequence features
characteristic of other mammal control regions were also evident in
marmosets, with the exception that conserved sequence blocks (CSBs) 2 and 3
were not clearly identifiable. Tandem repeat units often associated with
heteroplasmy in a variety of other mammals were not evident in the marmoset
sequences.
相似文献
35.
ALEXEY V. F. CH. BOBROV PETER K. ENDRESS ALEXANDER P. MELIKIAN MIKHAIL S. ROMANOV ALEXEY N. SOROKIN ALEJANDRO PALMAROLA BEJERANO 《Botanical journal of the Linnean Society. Linnean Society of London》2005,148(3):265-274
The indehiscent fruitlets of the apparently basalmost extant angiosperm, Amborella trichopoda, have a pericarp that is differentiated into five zones, a thin one‐cell‐layered skin (exocarp), a thick fleshy zone of 25–35 cell layers (outer mesocarp), a thick, large‐celled sclerenchymatous zone (unlignified) of 6–18 cell layers (middle mesocarp), a single cell layer with thin‐walled (silicified?) cells (inner mesocarp), and a 2–4‐cell‐layered, small‐celled sclerenchymatous zone (unlignified) derived from the inner epidermis (endocarp). The border between inner and outer mesocarp is not even but the inner mesocarp forms a network of ridges and pits; the ridges support the vascular bundles, which are situated in the outer mesocarp. In accordance with previous observations by Bailey & Swamy, no ethereal oil cells were observed in the pericarp; however, lysigenous cavities as mentioned by these authors are also lacking; they seem to be an artefact caused by re‐expanding dried fruits. The seed coat is not sclerified. The fruitlets of Amborella differ from externally similar fruits or fruitlets in other basal angiosperms, such as Austrobaileyales or Laurales, in their histology. © 2005 The Linnean Society of London, Botanical Journal of the Linnean Society, 2005, 148 , 265–274. 相似文献
36.
C. TH. Buchelos C. G. Athanassiou C. CH. Papapostolou A. Georgiou 《Journal of Applied Entomology》1999,123(7):433-436
In order to evaluate the influence of the number of catches in pheromone-baited traps on the percentage of larval infestation, six delta traps equipped with sex attractant were placed in each of three regions in Central Greece (Farkadona, Farsala, Almyros) in cotton fields from 20 June until 30 September 1995. The collection of fruiting bodies took place weekly and the counting of adults in the traps was carried out each day. The population fluctuation in all three regions was similar with their peak during the first weeks of August. In Farkadona the infestation level was low (1% at the first sampling of August) with a maximum of 9% in the last sampling of September. In Farsala and Almyros, the infestation level was already high (10% and above) in early August. There was a significant positive linear correlation between the number of moth catches and the infestation percentage from first- and second-stage larvae on the first (R = 0694) and second (R = 0.7399) boll-feeding generations. 相似文献
37.
Active and passive cation transport and L antigen hertogeneity in low potassium sheep red cells 下载免费PDF全文
Several lines of experimental evidence are presented suggesting that the L antigens in low potassium (LK) sheep red cells are associated with separate Na(+)K(+) pump flux is distinct from the action of anti-L(l) on K(+) leak flux, implying that K(+) leak transport sites may not be converted into active pumps by the L antiserum. Treatment of LK red cells with trypsin completely abolished both the stimulation of K(+) pump flux and the enhancement of the rate of ouabain binding brought about by anti- L. That this effect is due to a total destruction of the L(p) determinant associated with the LK pump was evident from the complete failure of anti-L(p) to bind to trypsinized LK red cells. The L(p) antigen can be effectively protected against the trypsin attack by prior incubation with anti-L, indicating that the sites for antibody binding and trypsin action may be closely adjacent at the structural level. Trypsin treatment, however, did not interfere with anti-L(l) reducing ouabain insensitive K(+) leak influx, nor did it prevent binding of anti-L(ly), the hemolytically active L antibody which is probably identical with anti-L(l). The functional independence of the L(p) and L(l) sites was documented by the observation that anti-L(l) still reduced K(+) leak influx in LK cells with experimentally induced high potassium concentrations, at which K(+) pump flux is fully suppressed, whether or not anti-L(p) was binding to the L(p) antigen associated with the LK pump. 相似文献
38.
39.
Quenching of the amidolytic activity of one-chain tissue-type plasminogen activator by mutation of lysine-416 总被引:1,自引:0,他引:1
In contrast to most other serine proteases, tissue-type plasminogen activator (t-PA) possesses enzymatic activity as the one-chain zymogen form. The hypothesis that lysine residues 277 or 416 may be involved in stabilization of an active conformation of one-chain t-PA via salt-bridge formation with aspartic acid residue 477 was tested by site-directed mutagenesis. Four recombinant t-PA mutants were constructed. The amidolytic activities of these analogues were compared to that of authentic t-PA. Substitution of arginine-275 provided an analogue [( R275G]t-PA) resistant to plasmin cleavage. The amidolytic activity of [R275G]t-PA was comparable to that of authentic one-chain t-PA, and so was the activity of [R275L,K277L]t-PA, in which additional substitution of lysine residue 277 was carried out. This suggested that its presence was nonessential for obtaining one-chain t-PA activity. In contrast, substitution of lysine residue 416 to obtain [K416S]t-PA and [K416S,H417T]t-PA resulted in substantial quenching of amidolytic one-chain activity. As expected, the amidolytic activities of the two-chain forms were less affected by the substitution. Involvement of lysine residue 416 in one-chain t-PA activity was also indicated by decreased activities of [K416S]t-PA and [K416S,H417T]t-PA with plasminogen as the substrate. The one-chain activity of the lysine residue 416 substitution analogues was partially restored in the presence of fibrin. This could indicate that strong ligands such as fibrin might provide an alternative stabilization of the active conformation of one-chain t-PA. 相似文献
40.
Hildur Helgadottir Emilia Andersson Lisa Villabona Lena Kanter Henk van der Zanden Geert W. Haasnoot Barbara Seliger Kjell Bergfeldt Johan Hansson Boel Ragnarsson-Olding Rolf Kiessling Giuseppe Valentino Masucci 《Cancer immunology, immunotherapy : CII》2009,58(10):1599-1608
Purpose We have previously demonstrated an association of the human leukocyte antigen (HLA), HLA-A2 allele with ovarian and prostate
cancer mortality as well as a segregation of the ancestral HLA haplotype (AHH) 62.1 [(A2) B15 Cw3 DRB1*04] in patients with
stage III–IV serous ovarian cancer. The objective of the present study was to determine the role of the HLA phenotype on the
prognosis in stage III–IV malignant melanoma patients.
Patients and methods A cohort of metastatic malignant melanoma patients (n = 91), in stage III (n = 26) or IV (n = 65) were analysed for HLA-A, -B, -Cw and -DRB1 types by PCR/sequence-specific primer method. The frequencies of HLA alleles
in the patients were compared to that of healthy Swedish bone marrow donors. The effect of HLA types on prognosis was defined
by Kaplan–Meier and Cox analysis.
Results The presence of the AHH 62.1 in clinical stage IV patients was significantly and independently associated with the worst survival
rate recorded from the appearance of metastasis (HR = 2.14; CI = 1.02–4.4; P = 0.04). In contrast, the period from the primary diagnosis to metastasis was the longest in patients with this haplotype
(HR = 0.40; CI = 0.17–0.90; P = 0.02).
Conclusions Melanoma patients in our cohort with 62.1 AHH which is associated with autoimmune diseases have an initial strong anti-tumour
control with longer metastasis-free period. These patients have rapid progression after the appearance of metastasis, responding
poorly to chemo- or/and immunotherapy. This apparently paradoxical clinical process could be due to the interplay between
tumour clones escape and immune surveillance ending up with a rapid disease progression.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献