全文获取类型
收费全文 | 4243篇 |
免费 | 300篇 |
出版年
2024年 | 4篇 |
2023年 | 21篇 |
2022年 | 66篇 |
2021年 | 125篇 |
2020年 | 95篇 |
2019年 | 88篇 |
2018年 | 131篇 |
2017年 | 112篇 |
2016年 | 169篇 |
2015年 | 247篇 |
2014年 | 281篇 |
2013年 | 284篇 |
2012年 | 342篇 |
2011年 | 351篇 |
2010年 | 252篇 |
2009年 | 198篇 |
2008年 | 241篇 |
2007年 | 233篇 |
2006年 | 211篇 |
2005年 | 186篇 |
2004年 | 144篇 |
2003年 | 139篇 |
2002年 | 113篇 |
2001年 | 53篇 |
2000年 | 47篇 |
1999年 | 52篇 |
1998年 | 29篇 |
1997年 | 26篇 |
1996年 | 16篇 |
1995年 | 12篇 |
1994年 | 17篇 |
1993年 | 10篇 |
1992年 | 24篇 |
1991年 | 25篇 |
1990年 | 21篇 |
1989年 | 20篇 |
1988年 | 23篇 |
1987年 | 16篇 |
1986年 | 11篇 |
1985年 | 19篇 |
1984年 | 11篇 |
1983年 | 12篇 |
1982年 | 8篇 |
1981年 | 8篇 |
1980年 | 13篇 |
1978年 | 4篇 |
1973年 | 5篇 |
1972年 | 3篇 |
1968年 | 3篇 |
1967年 | 3篇 |
排序方式: 共有4543条查询结果,搜索用时 31 毫秒
821.
Walter Moises Tobias Braga Bruna Raphaeli da Silva Ana Carolina de Carvalho Yumi H. Maekawa Adriana Bruscato Bortoluzzo Edgar Gil Rizzatti Djordje Atanackovic Gisele Wally Braga Colleoni 《Cancer immunology, immunotherapy : CII》2014,63(11):1189-1197
Introduction
Multiple myeloma (MM) development involves a series of genetic abnormalities and changes in the bone marrow (BM) microenvironment, favoring the growth of the tumor and failure of local immune control. T regulatory (Treg) cells play an important role in dampening anti-tumor immune responses while T-helper-17 (Th17) cells seem to be critical for the eradication of malignant cells. The aim of our study was to characterize the expression of Treg- and Th17-related genes in total myeloma BM samples to assess their role as biomarkers, prognostic factors, and possible therapeutic targets in this incurable disease.Methods
Expression of markers for Treg (FOXP3, CTLA4) and Th17 cells (RORγt) was determined by quantitative real-time PCR in BM aspirates of 46 MM patients, four patients with monoclonal gammopathy of undetermined significance, five solitary plasmacytomas, and five healthy BM donors. Gene expression was evaluated regarding an influence on the patients’ overall survival (OS).Results
FOXP3 and CTLA4 presented a sixfold (p = 0.02) and 30-fold higher expression (p = 0.03), respectively, in MM patients than in controls. RORγt expression was similar in MM patients and controls. Median OS of MM patients was 16.8 (range 4.5–29.1) months, and international staging system was the only independent prognostic factor for patients survival.Conclusions
Overexpression of FOXP3 and CTLA4 in total BM samples suggests a local accumulation of immunosuppressive Tregs, the MM tumor environment, possibly dampening anti-tumor host immune responses. Therapeutic approaches targeting Treg cells and restoring local anti-tumor immunity may provide new treatment strategies for this incurable malignancy. 相似文献822.
Juliana F. Santos-Gandelman Kimberly Cruz Sharron Crane Guilherme Muricy Marcia Giambiagi-deMarval Tamar Barkay Marinella S. Laport 《Current microbiology》2014,69(3):374-380
Sponges are sessile marine invertebrates that can live for many years in the same location, and therefore, they have the capability to accumulate anthropogenic pollutants such as metals over a long period. Almost all marine sponges harbor a large number of microorganisms within their tissues. The Bacillus cereus strain Pj1 was isolated from a marine sponge, Polymastia janeirensis, and was found to be resistant to 100 μM HgCl2 and to 10 μM methylmercury (MeHg). Pj1 was also highly resistant to other metals, including CdCl2 and Pb(NO3)2, alone or in combination. The mer operon was located on the bacterial chromosome, and the volatilization test indicated that the B. cereus Pj1 was able to reduce Hg2+–Hg0. Cold vapor atomic absorption spectrometry demonstrated that Pj1 volatilized 80 % of the total MeHg that it was exposed to and produced elemental Hg when incubated with 1.5 μM MeHg. Pj1 also demonstrated sensitivity to all antibiotics tested. In addition, Pj1 demonstrated a potential for biosurfactant production, presenting an emulsification activity better than synthetic surfactants. The results of this study indicate that B. cereus Pj1 is a strain that can potentially be applied in the bioremediation of HgCl2 and MeHg contamination in aquatic environments. 相似文献
823.
824.
Maria Juliana Calderan‐Rodrigues Elisabeth Jamet Maria Beatriz Calderan Rodrigues Bonassi Simone Guidetti‐Gonzalez Amanda Carmanhanis Begossi Laís Vaz Setem Livia Maria Franceschini Juliana Guimarães Fonseca Carlos Alberto Labate 《Proteomics》2014,14(6):738-749
The use of cell walls to produce cellulosic ethanol from sugarcane bagasse is a new challenge. A better knowledge of proteins involved in cell wall remodelling is essential to improve the saccharification processes. Cell suspension cultures were used for this first cell wall proteomics study of sugarcane. Proteins extracted from cell walls were identified using an adapted protocol. They were extracted using 0.2 M CaCl2 and 2 M LiCl after purification of cell walls. The proteins were then identified by the innovative nanoACQUITY UPLC MS/MS technology and bioinformatics using the translated SUCEST EST cluster database of sugarcane. The experiments were reproduced three times. Since Sorghum bicolor is the closest plant with a fully sequenced genome, homologous proteins were searched for to complete the annotation of proteins, that is, prediction of subcellular localization and functional domains. Altogether, 69 different proteins predicted to be secreted were identified among 377 proteins. The reproducibility of the experiments is discussed. These proteins were distributed into eight functional classes. Oxidoreductases such as peroxidases were well represented, whereas glycoside hydrolases were scarce. This work provides information about the proteins that could be manipulated through genetic transformation, to increase second‐generation ethanol production. 相似文献
825.
Caroline Tanski Bueno Cláudia Maria Dornelles da Silva Regina Bones Barcellos Juliana da Silva Carla Rossana dos Santos Jo?o Evangelista Sampaio Menezes Honório Sampaio Menezes Maria Lucia Rosa Rossetti 《Genetics and molecular biology》2014,37(3):496-499
The aim of this study was to evaluate the association between the frequency of micronuclei (MN) and the cellular changes detected in the conventional Papanicolaou test. One hundred and seventy-four Papanicolaou test smears with cellular changes were examined. MN screening was done in cytopathological smears by counting 1,000 cervical cells in a light microscope. MN frequencies were significantly higher in the group with cellular changes compared to the control group (p < 0.001). The mean MN frequencies were 0.95 ± 1.12 (mean ± SD) in the control group (n = 223), 2.98 ± 1.20 in individuals with atypical squamous cells of undetermined significance (ASC-US) (n = 50), 4.04 ± 1.45 in cervical intraepithelial neoplasia (CIN) I (n = 52), 5.97 ± 1.83 in CIN II (n = 30), 7.29 ± 1.55 in CIN III (n = 17) and 8.64 ± 1.55 in invasive cancer (n = 25). These findings suggest that MN monitoring should be included as an additional criterion for the early detection of cytogenetic damage in routine examinations. This monitoring should be done in the same smear as used for cytopathological examination. More specific and systematic studies are necessary to confirm this proposal. 相似文献
826.
Laura Vicedo Jacociunas Rafael Rodrigues Dihl Mauricio Lehmann Alexandre de Barros Falc?o Ferraz Marc Fran?ois Richter Juliana da Silva Heloísa Helena Rodrigues de Andrade 《Genetics and molecular biology》2014,37(1):90-104
The genotoxicity of bloom head (BHE) and leaf (LE) extracts from artichoke (Cynara scolymus L.), and their ability to modulate the mutagenicity and recombinogenicity of two alkylating agents (ethyl methanesulfonate – EMS and mitomycin C – MMC) and the intercalating agent bleomycin (BLM), were examined using the somatic mutation and recombination test (SMART) in Drosophila melanogaster. Neither the mutagenicity nor the recombinogenicity of BLM or MMC was modified by co- or post-treatment with BHE or LE. In contrast, co-treatment with BHE significantly enhanced the EMS-induced genotoxicity involving mutagenic and/or recombinant events. Co-treatment with LE did not alter the genotoxicity of EMS whereas post-treatment with the highest dose of LE significantly increased this genotoxicity. This enhancement included a synergistic increase restricted to somatic recombination. These results show that artichoke extracts promote homologous recombination in proliferative cells of D. melanogaster. 相似文献
827.
We studied the seed predation and scatter‐hoarding behaviour of Azara's agoutis Dasyprocta azarae (Rodentia: Dasyproctidae) in relation to the seeds of the Brazilian ‘pine’, Araucaria angustifolia (Araucariaceae), the rodent's main winter food source. We compared seed‐removal rates, seed‐caching rates, cache distances and recovery rates between a summer period of food abundance (with a low demand for A. angustifolia seeds and no such seeds naturally available) and a winter period of food scarcity (with a high demand for A. angustifolia seeds). We investigated whether the relative seed value affected the rodent's seed‐handling behaviour. We predicted that during the high seed‐demand period (winter): (1) cache distances would be greater; (2) fewer seeds would be stored; (3) more seeds would be recovered and the seed‐recovery time would be lower. In support of our first two predictions, the caching distances were greater in winter (mean ± SE = 15.67 ± 5.11 m) than in summer (9.40 ± 1.59 m), and agoutis hoarded >9 times more seeds in summer (55) than in winter (6). Our third prediction was not supported, and the proportion of unrecovered caches and buried seed recovery times did not differ between winter (mean ± SE = 3.00 ± 0.00 days, n = 5 seeds) and summer (11.05 ± 3.68 days, n = 20 seeds). The high resource density (during summer) rather than the density of A. angustifolia seeds likely influenced seed fate. Agoutis acted mainly as predators, leaving few intact seeds, caching a low proportion of handled seeds (? 8%) and rapidly consuming the caches. Agoutis may cache seeds to keep them safe from competitors on a short‐term basis rather than maintaining medium‐ or long‐term reserves for use during food‐scarcity periods. 相似文献
828.
829.
Camila M Bonocher Mary L Montenegro Julio C Rosa e Silva Rui A Ferriani Juliana Meola 《Reproductive biology and endocrinology : RB&E》2014,12(1):1-5
Regular physical exercise seems to have protective effects against diseases that involve inflammatory processes since it induces an increase in the systemic levels of cytokines with anti-inflammatory and antioxidant properties and also acts by reducing estrogen levels. Evidence has suggested that the symptoms associated with endometriosis result from a local inflammatory peritoneal reaction caused by ectopic endometrial implants. Thus, the objective of the present review was to assess the relationship between physical exercise and the prevalence and/or improvement of the symptoms associated with endometriosis. To this end, data available in PubMed (1985–2012) were surveyed using the terms “endometriosis and physical exercises”, “endometriosis and life style and physical exercises” in the English language literature. Only 6 of the 935 articles detected were included in the study. These studies tried establish a possible relationship between the practice of physical exercise and the prevalence of endometriosis. The data available are inconclusive regarding the benefits of physical exercise as a risk factor for the disease and no data exist about the potential impact of exercise on the course of the endometriosis. In addition, randomized studies are necessary. 相似文献
830.
Sharifa Alebrahim Zohreh Khavandgar Juliana Marulanda Monzur Murshed 《Genesis (New York, N.Y. : 2000)》2014,52(5):408-416
Sphingomyelin phosphodiesterase 3 (SMPD3) is a pleiotropic lipid metabolizing enzyme involved in multiple physiological processes. A deletion mutation in the murine Smpd3 gene called fragilitas ossium (fro) leads to severe skeletal abnormalities in the developing fro/fro embryos. Although fro/fro mice can be useful to study many different aspects of SMPD3 functions, their perinatal lethality makes it difficult to generate a sufficient number of mice for controlled studies. In fact, on the C57BL/6 genetic background, none of the fro/fro mice survive beyond the perinatal stage. In this study, we used the “Tet‐On” inducible gene expression system to express Smpd3 transiently in fro/fro;ROSA‐rtTA;TRE‐Smpd3 embryos on the C57BL/6 background. This induced Smpd3 expression corrected all the skeletal abnormalities in these embryos and prevented their early death. However, induction of Smpd3 expression in the adolescent fro/fro;ROSA‐rtTA;TRE‐Smpd3 mice was not sufficient to correct the defects in trabecular bone mineralization and the impaired growth of the long bones. This novel mouse model will be a useful tool to study SMPD3 biology in vivo. genesis 52:408–416, 2014. © 2014 Wiley Periodicals, Inc. 相似文献