全文获取类型
收费全文 | 1209篇 |
免费 | 88篇 |
出版年
2023年 | 4篇 |
2022年 | 16篇 |
2021年 | 17篇 |
2020年 | 17篇 |
2019年 | 33篇 |
2018年 | 37篇 |
2017年 | 18篇 |
2016年 | 49篇 |
2015年 | 65篇 |
2014年 | 65篇 |
2013年 | 86篇 |
2012年 | 85篇 |
2011年 | 105篇 |
2010年 | 59篇 |
2009年 | 44篇 |
2008年 | 66篇 |
2007年 | 90篇 |
2006年 | 70篇 |
2005年 | 55篇 |
2004年 | 50篇 |
2003年 | 46篇 |
2002年 | 33篇 |
2001年 | 9篇 |
2000年 | 11篇 |
1999年 | 13篇 |
1998年 | 11篇 |
1997年 | 7篇 |
1996年 | 17篇 |
1995年 | 5篇 |
1994年 | 14篇 |
1993年 | 3篇 |
1992年 | 6篇 |
1991年 | 15篇 |
1989年 | 5篇 |
1988年 | 4篇 |
1987年 | 3篇 |
1986年 | 4篇 |
1985年 | 6篇 |
1983年 | 8篇 |
1980年 | 3篇 |
1977年 | 7篇 |
1976年 | 5篇 |
1974年 | 2篇 |
1973年 | 3篇 |
1972年 | 5篇 |
1971年 | 3篇 |
1970年 | 2篇 |
1968年 | 2篇 |
1967年 | 3篇 |
1966年 | 3篇 |
排序方式: 共有1297条查询结果,搜索用时 218 毫秒
1.
2.
Chiara D'Onofrio Caterina D. Pesce Tecla Fontana Fabrizio Ciprani Enzo Bonmassar Raffaele Calio 《Cancer immunology, immunotherapy : CII》1990,31(4):213-220
Summary Infection with human T-cell leukemia virus type I (HTLV-I) is associated in vitro and in vivo with a remarkable depression of cell-mediated immune functions. In the present report it is shown that early events following virus-induced suppression of the cell-mediated immune response of freshly isolated cord blood mononuclear cells (CBL) infected with HTLV-I can be partially counteracted by treatment with interferons , or (IFN). All three types of IFN exerted a protective effect on CBL cultures exposed to the virus. This resulted in: (a) a reduced number of virus-positive cells until 4 weeks of culture; (b) delay in the clonal expansion of infected cells (IFN and ); (c) increased natural killer cell activity of CBL, 1 week post-infection (p.i.), mediated by IFN; (d) increase of allospecific recognition of infecting and priming HTLV-I donor MT-2 cells by CBL in a cytotoxic-T-lymphocyte-like response, mediated by IFN and particularly by IFN; (e) phenotype distribution of CBL subpopulations, tested 4 days p.i., more similar to that of non-infected CBL cultures.In contrast, the overall CBL proliferation, that is profoundly depressed during the first week p.i., was not restored by IFN treatments, suggesting that boosting of the cell-mediated killing induced by IFN might involve the maturation of undifferentiated precursor cells rather than stimulation of their proliferation. The improvement of the efficiency of the antiviral immune response induced by treatment with IFN is likely to contribute to the clearance of virus-positive cells during the early phase of infection. This would provide experimental evidence to support an immunopharmacological approach contributing to the conversion of HTLV-I carriers from positive to negative. 相似文献
3.
4.
M. Rizzardini A. Graziani C. Carugo L. Cantoni 《Journal of biochemical and molecular toxicology》1988,3(1):33-45
Male C57BY/10 mice were chronically fed hexachlorobenzene (HCB) (0.02% of the diet) alone or in combination with a single subcutaneous dose of iron (12.5 mg iron per mouse). After eight weeks the group of mice pretreated with the iron overload was highly sensitized to the porphyrogenic effect of HCB, as shown by liver porphyrin accumulation. A synergistic effect of iron was evident on other parameters too, such as HCB-induced hepatic damage, activation of type O of xanthine oxidase, and decreased activity of copper zinc superoxide dismutase and glutathione peroxidase(s). None of these parameters was affected by iron alone. Iron alone and in association with HCB markedly raised the level of lipid peroxides, the increase in the HCB group being smaller. The combined treatment resulted in a significant reduction of HCB's inductive effects on microsomal heme and cytochromes P-450 and b5 and on the activity of aryl hydrocarbon hydroxylase. The content of nonprotein sulfhydryl groups was reduced to the same extent in mice treated with HCB or HCB plus iron. The results suggest that reactive intermediates such as are formed by lipid peroxidation are not sufficient on their own to create the conditions for uroporphyrinogen decarboxylase impairment, as evident in the group of mice receiving iron overload alone. Conversely, HCB administration induced a specific condition of imbalance in the liver between formation and inactivation of reactive intermediates which was associated with hepatic porphyrin accumulation and was potentiated by concomitant administration of iron. 相似文献
5.
Valeria Cavaliere Franco Graziani Silvia Andone Andrea Manzi Carla Malva 《Molecular & general genetics : MGG》1991,230(3):433-441
Summary The abnormal oocyte phenotype is characterized by instability, as shown by the loss and reappearance of the abo maternal effect under specific genetic conditions. Our previous finding that a correlation exists between the abo phenotype and the presence of a blood transposon in region 32E, led us to perform an extensive genetic and molecular analysis of the most significant aspects of the abo phenotype in different genetic backgrounds. The results of these experiments can be summarized as follows: Complete reversion occurs only when the blood transposon is lost, thus definitively demonstrating that the insertion of the blood transposon in region 32E is the molecular event that causes the pleiotropic abo phenotype. Partial reversion can also occur without loss of the transposon, indicating that different molecular pathways may be involved in the loss of the abo phenotype. Reappearance of the full abo phenotype can occur only in heterozygous lines constructed from partially revertant abo homozygous lines that have not lost the blood transposon. 相似文献
6.
The candidate gene for the X-linked Kallmann syndrome encodes a protein related to adhesion molecules 总被引:34,自引:0,他引:34
R Legouis J P Hardelin J Levilliers J M Claverie S Compain V Wunderle P Millasseau D Le Paslier D Cohen D Caterina 《Cell》1991,67(2):423-435
Kallmann syndrome associates hypogonadotropic hypogonadism and anosmia and is probably due to a defect in the embryonic migration of olfactory and GnRH-synthesizing neurons. The Kallmann gene had been localized to Xp22.3. In this study 67 kb of genomic DNA, corresponding to a deletion interval containing at least part of the Kallmann gene, were sequenced. Two candidate exons, identified by multiparameter computer programs, were found in a cDNA encoding a protein of 679 amino acids. This candidate gene (ADMLX) is interrupted in its 3' coding region in the Kallmann patient, in which the proximal end of the KAL deletion interval was previously defined. A 5' end deletion was detected in another Kallmann patient. The predicted protein sequence shows homologies with the fibronectin type III repeat. ADMLX thus encodes a putative adhesion molecule, consistent with the defect of embryonic neuronal migration. 相似文献
7.
8.
Effects of atrial natriuretic factor on human platelet function 总被引:1,自引:0,他引:1
We examined the hypothesis that atrial natriuretic factor (ANF), a substance with known vasorelaxant activities, shares with other vasodilators the property of inhibiting platelet function. Aggregation of citrated platelet-rich plasma (PRP) from 23 healthy volunteers induced by ADP, adrenaline, arachidonic acid, collagen, gamma-thrombin, the endoperoxide analogue U-44069, serotonin, the calcium ionophore A-23187 or platelet aggregating factor was measured after incubation of PRP with ANF for 3 minutes at concentrations of 4 X 10(-9), 4 X 10(-8) and 4 X 10(-7) M or vehicle as control. ANF decreased ADP-induced aggregation significantly (P less than 0.02), but only at the highest concentration used and to a minor extent (control: 73.6 +/- 11.2%; after ANF 4 X 10(-7) M: 60.0 +/- 17.1%, mean +/- S.D., n = 39) by a selective inhibitory effect on the secondary wave; neither aggregation by all other agents tested nor thromboxane B2 generation induced by ADP and adrenaline was altered by incubation with ANF. Although ANF thus has detectable effects on ADP-induced platelet aggregation in vitro, these data suggest that ANF is unlikely to be a physiologically significant modulator of platelet function. 相似文献
9.
Lucio Annunziato Salvatore Amoroso Gianfranco Di Renzo Filomena Argenzio Caterina Aurilio Antonio Grella Aldo Quattrone 《Life sciences》1983,33(26):2651-2655
In humans the release of growth hormone (GH) elicited by dopamine (DA) and DA agonists may represent a reliable model to assess change in sensitivity of DA receptors. We now report that in chronic alcoholics, 4–7 days after the suspension of alcohol consumption, the increase of GH response to DA infusion was higher than that seen in non alcoholic volunteers. The specificity of this GH response to DA administration was demonstrated by the use of domperidone, a novel peripheral antagonist of DA receptors. These results suggest the development of hyper-responsiveness of DA receptors involved in the control of GH secretion in chronic alcoholics during the later phases of the “withdrawal syndrome”. 相似文献
10.
Caterina Crescimanno Jean-Michel Foidart Agns Noël Myriam Polette Erik Maquoi Philippe Birembaut Eugenia Baramova Peter Kaufmann Mario Castellucci 《Experimental cell research》1996,227(2):240
Implantation and placental development are dependent upon trophoblast invasion of the endometrium. While the villous trophoblast does not display invasive behavior, the extravillous cytotrophoblast is highly invasive. By cloning BeWo choriocarcinoma cells, we have isolated two distinct clones that share similarities with villous and extravillous cytotrophoblasts. When cultured at the surface of a type I collagen gel, BeWo MC-1 cells were not invasive, whereas BeWo MC-2 cells rapidly invaded this matrix. When injected subcutaneously in nude mice, BeWo MC-1 cells developed a localized tumor and BeWo MC-2 cells developed larger tumors with micrometastases. Gelatinase A expression and minute amounts of gelatinase B were detected in the parental cell line and in both clones. However, the parental and the BeWo MC-2 cells secreted 5- to 10-fold more gelatinase A than the BeWo MC-1 cells. Laminin and matrigel stimulated the production of gelatinase A in BeWo MC-2 cells. Type I collagen promoted the conversion of the 72-kDa progelatinase A in an active enzyme only in parental BeWo and in BeWo MC-2 cells. These clones provide an interesting model for studying the complex mechanisms regulating implantation as well as the controlled invasiveness during implantation compared to tumor invasion. 相似文献