全文获取类型
收费全文 | 7679篇 |
免费 | 516篇 |
国内免费 | 3篇 |
专业分类
8198篇 |
出版年
2023年 | 48篇 |
2022年 | 94篇 |
2021年 | 181篇 |
2020年 | 108篇 |
2019年 | 128篇 |
2018年 | 173篇 |
2017年 | 190篇 |
2016年 | 269篇 |
2015年 | 420篇 |
2014年 | 435篇 |
2013年 | 522篇 |
2012年 | 624篇 |
2011年 | 531篇 |
2010年 | 353篇 |
2009年 | 317篇 |
2008年 | 400篇 |
2007年 | 442篇 |
2006年 | 384篇 |
2005年 | 358篇 |
2004年 | 340篇 |
2003年 | 317篇 |
2002年 | 297篇 |
2001年 | 86篇 |
2000年 | 51篇 |
1999年 | 88篇 |
1998年 | 83篇 |
1997年 | 62篇 |
1996年 | 51篇 |
1995年 | 59篇 |
1994年 | 54篇 |
1993年 | 55篇 |
1992年 | 48篇 |
1991年 | 49篇 |
1990年 | 53篇 |
1989年 | 33篇 |
1988年 | 36篇 |
1987年 | 16篇 |
1986年 | 30篇 |
1985年 | 28篇 |
1984年 | 29篇 |
1983年 | 19篇 |
1982年 | 28篇 |
1981年 | 24篇 |
1980年 | 14篇 |
1979年 | 17篇 |
1977年 | 12篇 |
1976年 | 19篇 |
1975年 | 13篇 |
1974年 | 21篇 |
1970年 | 16篇 |
排序方式: 共有8198条查询结果,搜索用时 0 毫秒
211.
Viviana Volta Elia Ranzato Simona Martinotti Simone Gallo Maria Veronica Russo Luciano Mutti Stefano Biffo Bruno Burlando 《PloS one》2013,8(3)
Malignant pleural mesothelioma (MPM) is a poor prognosis disease lacking adequate therapy. We have previously shown that ascorbic acid administration is toxic to MPM cells. Here we evaluated a new combined therapy consisting of ascorbate/epigallocatechin-3-gallate/gemcitabine mixture (called AND, for Active Nutrients/Drug). In vitro effects of AND therapy on various MPM cell lines revealed a synergistic cytotoxic mechanism. In vivo experiments on a xenograft mouse model for MPM, obtained by REN cells injection in immunocompromised mice, showed that AND strongly reduced the size of primary tumor as well as the number and size of metastases, and prevented abdominal hemorrhage. Kaplan Meier curves and the log-rank test indicated a marked increase in the survival of AND-treated animals. Histochemical analysis of dissected tumors showed that AND induced a shift from cell proliferation to apoptosis in cancer cells. Lysates of tumors from AND-treated mice, analyzed with an antibody array, revealed decreased TIMP-1 and -2 expressions and no effects on angiogenesis regulating factors. Multiplex analysis for signaling protein phosphorylation exhibited inactivation of cell proliferation pathways. The complex of data showed that the AND treatment is synergistic in vitro on MPM cells, and blocks in vivo tumor progression and metastasization in REN-based xenografts. Hence, the AND combination is proposed as a new treatment for MPM. 相似文献
212.
213.
da Silva-Carvalho Lidiane Maria Genovez-Oliveira Jhon Lennon de Souza Oliveira Mariana de Oliveira Águida Aparecida de Lima Viviane Moreira Ferreira Ildemar Berto Bruno Pereira 《Systematic parasitology》2020,97(6):847-855
Systematic Parasitology - Isospora parnaitatiaiensis Silva, Rodrigues, Lopes, Berto, Luz, Ferreira & Lopes, 2015 was identified from a new host, the plain antvireo Dysithamnus mentalis... 相似文献
214.
Marcelo F. G. Brito Ayda V. Alcântara Daniela C. O. Rosa Bruno E. Soares 《Zeitschrift fur angewandte Ichthyologie》2020,36(5):753-756
Length-weight relationships (LWR) and length-length relationships (LLR) were provided for eight species inhabiting Northeastern Brazilian coast. Nine transects (5, 15, 30 m deep) between Sergipe and Vaza-Barris rivers mouths were sampled monthly from September 2013 to August 2014. Each sampling was carried out using a shrimp boat equipped with double ring nets (4 m mouth wide, 10 m long and 20 mm mesh size) and trawlings were performed for 15 min. Fishes were measured (standard and total length, 0.1 cm) and weighted (total weight, 0.01 g). We provide LWR and LLR coefficients for these eight species, including new maximum TL for five species, and discuss the similarity of these results with estimates available in Fishbase. 相似文献
215.
Pereira Isabela Tiemy Spangenberg Lucia Cabrera Guillermo Dallagiovanna Bruno 《Molecular and cellular biochemistry》2020,466(1-2):35-44
Molecular and Cellular Biochemistry - In stress conditions, as neoplastic transformation, amino acids serve not only as nutrients to maintain the cell survival but also as mediators of several... 相似文献
216.
Hudson T. Pinheiro Bruno C. L. Macena Ronaldo B. Francini-Filho Carlos E. L. Ferreira Fernanda V. Albuquerque Natalia P. A. Bezerra Alfredo Carvalho-Filho Romulo C. P. Ferreira Osmar J. Luiz Thayna J. Mello Sibele A. Mendonça Diogo M. Nunes Caio R. Pimentel Alessandra M. A. Pires Abilio Soares-Gomes Danielle L. Viana Fabio H. V. Hazin Luiz A. Rocha 《Journal of fish biology》2020,97(4):1143-1153
Saint Peter and Saint Paul's Archipelago (SPSPA), one of the smallest and most isolated island groups in the world, is situated on the Mid-Atlantic Ridge, between Brazil and the African continent. SPSPA has low species richness and high endemism; nonetheless, the diversity of fishes from deep habitats (>30 m depth) had not been previously studied in detail. Several expeditions conducted between 2009 and 2018 explored the shallow and deep reefs of SPSPA using scuba, closed-circuit rebreathers, manned submersibles, baited remote underwater stereo-videos (stereo-BRUV) and fishing between 0 and 1050 m depth. These expeditions yielded 41 new records of fishes for SPSPA: 9 in open waters, 9 in shallow waters (0–30 m), 8 in mesophotic ecosystems (30–150 m) and 15 in deeper reefs (>150 m). Combined with literature records of adult pelagic, shallow and deep-reef species, as well as larvae, the database of the fish biodiversity for SPSPA currently comprises 225 species (169 recorded as adult fishes and 79 as larvae, with 23 species found in both stages). Most of them (112) are pelagic, 86 are reef-associated species and 27 are deep-water specialists. Species accumulation curves show that the number of fish species has not yet reached an asymptote. Whereas the number of species recorded in SPSPA is similar to that in other oceanic islands in the Atlantic Ocean, the proportion of shorefishes is relatively lower, and the endemism level is the third highest in the Atlantic. Twenty-nine species are listed as threatened with extinction. Observations confirm the paucity of top predators on shallow rocky reefs of the island, despite the presence of several pelagic shark species around SPSPA. Because all of the endemic species are reef associated, it is argued that the new marine-protected areas created by the Brazilian government do not ensure the protection and recovery of SPSPA's biodiversity because they allow exploitation of the most vulnerable species around the archipelago itself. This study suggests a ban on reef fish exploitation inside an area delimited by the 1000 m isobath around the islands (where all known endemics are concentrated) as the main conservation strategy to be included in the SPSPA management plan being prepared by the Brazilian government. 相似文献
217.
Alexis Rodriguez Marie Ø. Pedersen Elba Villegas Bruno Rivas-Santiago Jessica Villegas-Moreno Carlos Amero Raymond S. Norton Gerardo Corzo 《Proteins》2020,88(1):175-186
The spread of multidrug resistant bacteria owing to the intensive use of antibiotics is challenging current antibiotic therapies, and making the discovery and evaluation of new antimicrobial agents a high priority. The evaluation of novel peptide sequences of predicted antimicrobial peptides from different sources is valuable approach to identify alternative antibiotic leads. Two strategies were pursued in this study to evaluate novel antimicrobial peptides from the human β-defensin family (hBD). In the first, a 32-residue peptide was designed based on the alignment of all available hBD primary structures, while in the second a putative 35-residue peptide, hBD10, was mined from the gene DEFB110. Both hBDconsensus and hBD10 were chemically synthesized, folded and purified. They showed antimicrobial activity against Escherichia coli, Staphylococcus aureus, and Mycobacterium tuberculosis, but were not hemolytic on human red blood cells. The NMR-based solution structure of hBDconsensus revealed that it adopts a classical β-defensin fold and disulfide connectivities. Even though the mass spectrum of hBD10 confirmed the formation of three disulfide bonds, it showed limited dispersion in 1H NMR spectra and structural studies were not pursued. The evaluation of different β-defensin structures may identify new antimicrobial agents effective against multidrug-resistant bacterial strains. 相似文献
218.
Hydrobiologia - Extreme climatic events, such as heat waves, may induce changes in nutrient acquisition by omnivorous ectotherms. Likely modulated by the intensity, frequency and duration of these... 相似文献
219.
Cyrille Gavazzi Catherine Isel Emilie Fournier Vincent Moules Annie Cavalier Daniel Thomas Bruno Lina Roland Marquet 《Nucleic acids research》2013,41(2):1241-1254
The genome of influenza A viruses (IAV) is split into eight viral RNAs (vRNAs) that are encapsidated as viral ribonucleoproteins. The existence of a segment-specific packaging mechanism is well established, but the molecular basis of this mechanism remains to be deciphered. Selective packaging could be mediated by direct interaction between the vRNA packaging regions, but such interactions have never been demonstrated in virions. Recently, we showed that the eight vRNAs of a human H3N2 IAV form a single interaction network in vitro that involves regions of the vRNAs known to contain packaging signals in the case of H1N1 IAV strains. Here, we show that the eight vRNAs of an avian H5N2 IAV also form a single network of interactions in vitro, but, interestingly, the interactions and the regions of the vRNAs they involve differ from those described for the human H3N2 virus. We identified the vRNA sequences involved in five of these interactions at the nucleotide level, and in two cases, we validated the existence of the interaction using compensatory mutations in the interacting sequences. Electron tomography also revealed significant differences in the interactions taking place between viral ribonucleoproteins in H5N2 and H3N2 virions, despite their canonical ‘7 + 1’ arrangement. 相似文献
220.