全文获取类型
收费全文 | 2691篇 |
免费 | 248篇 |
出版年
2023年 | 7篇 |
2022年 | 17篇 |
2021年 | 36篇 |
2020年 | 23篇 |
2019年 | 36篇 |
2018年 | 58篇 |
2017年 | 43篇 |
2016年 | 86篇 |
2015年 | 115篇 |
2014年 | 135篇 |
2013年 | 147篇 |
2012年 | 198篇 |
2011年 | 197篇 |
2010年 | 150篇 |
2009年 | 138篇 |
2008年 | 176篇 |
2007年 | 165篇 |
2006年 | 133篇 |
2005年 | 129篇 |
2004年 | 133篇 |
2003年 | 138篇 |
2002年 | 129篇 |
2001年 | 23篇 |
2000年 | 18篇 |
1999年 | 26篇 |
1998年 | 36篇 |
1997年 | 32篇 |
1996年 | 27篇 |
1995年 | 39篇 |
1994年 | 26篇 |
1993年 | 37篇 |
1992年 | 34篇 |
1991年 | 21篇 |
1990年 | 21篇 |
1989年 | 24篇 |
1988年 | 20篇 |
1987年 | 9篇 |
1986年 | 12篇 |
1985年 | 14篇 |
1984年 | 9篇 |
1983年 | 9篇 |
1982年 | 10篇 |
1981年 | 13篇 |
1980年 | 11篇 |
1978年 | 10篇 |
1977年 | 11篇 |
1975年 | 7篇 |
1972年 | 6篇 |
1970年 | 7篇 |
1967年 | 6篇 |
排序方式: 共有2939条查询结果,搜索用时 39 毫秒
101.
Christiane Segarra Daisy Bougard Mohammed Moudjou Hubert Laude Vincent Béringue Joliette Coste 《PloS one》2013,8(7)
Background
Variant Creutzfeldt-Jakob disease (vCJD) is a neurodegenerative infectious disorder, characterized by a prominent accumulation of pathological isoforms of the prion protein (PrPTSE) in the brain and lymphoid tissues. Since the publication in the United Kingdom of four apparent vCJD cases following transfusion of red blood cells and one apparent case following treatment with factor VIII, the presence of vCJD infectivity in the blood seems highly probable. For effective blood testing of vCJD individuals in the preclinical or clinical phase of infection, it is considered necessary that assays detect PrPTSE concentrations in the femtomolar range.Methodology/Principal Findings
We have developed a three-step assay that firstly captures PrPTSE from infected blood using a plasminogen-coated magnetic-nanobead method prior to its serial amplification via protein misfolding cyclic amplification (PMCA) and specific PrPTSE detection by western blot. We achieved a PrPTSE capture yield of 95% from scrapie-infected material. We demonstrated the possibility of detecting PrPTSE in white blood cells, in buffy coat and in plasma isolated from the blood of scrapie-infected sheep collected at the pre-clinical stage of the disease. The test also allowed the detection of PrPTSE in human plasma spiked with a 10−8 dilution of vCJD-infected brain homogenate corresponding to the level of sensitivity (femtogram) required for the detection of the PrPTSE in asymptomatic carriers. The 100% specificity of the test was revealed using a blinded panel comprising 96 human plasma samples.Conclusion/Significance
We have developed a sensitive and specific amplification assay allowing the detection of PrPTSE in the plasma and buffy coat fractions of blood collected at the pre-clinical phase of the disease. This assay represents a good candidate as a confirmatory assay for the presence of PrPTSE in blood of patients displaying positivity in large scale screening tests. 相似文献102.
103.
Usha R. Dutta Vijaya Kumar Pidugu Ch. Venkateshwar Goud Christiane Hoefers Monika Hagemann Ashwin Dalal 《Gene》2013
Ambiguous genitalia or disorder of the sexual development is a birth defect where the external genitals do not have the typical appearance of either a male or female. Here we report a boy with ambiguous genitalia and short stature. The cytogenetic analysis by G-banding revealed a small Y chromosome and an additional material on the 15p arm. Further, molecular cytogenetic analysis by Fluorescence in situ hybridization (FISH) using whole chromosome paint probes showed the presence of Y sequences on the 15p arm, confirming that it is a Y;15 translocation. Subsequent, FISH with centromere probe Y showed two signals depicting the presence of two centromeres and differing with a balanced translocation. The dicentric nature of the derivative 15 chromosome was confirmed by FISH with both 15 and Y centromeric probes. Further, the delineation of the Y chromosomal DNA was also done by quantitative real time PCR. Additional Y-short tandem repeat typing was performed to find out the extent of deletion on small Y chromosome. Fine mapping was carried out with 8 Y specific BAC clones which helped in defining the breakpoint regions. MLPA was performed to check the presence or absence of subtelomeric regions and SHOX regions on Y. Finally array CGH helped us in confirming the breakpoint regions. In our study we identified and characterized a novel complex Y chromosomal rearrangement with a complete deletion of the Yq region and duplication of the Yp region with one copy being translocated onto the15p arm. This is the first report of novel and unique Y complex rearrangement showing a deletion, duplication and a translocation in the same patient. The possible mechanism of the rearrangement and the phenotype–genotype correlation are discussed. 相似文献
104.
105.
106.
Eric Allan Wolfgang W. Weisser Markus Fischer Ernst-Detlef Schulze Alexandra Weigelt Christiane Roscher Jussi Baade Romain L. Barnard Holger Beßler Nina Buchmann Anne Ebeling Nico Eisenhauer Christof Engels Alexander J. F. Fergus Gerd Gleixner Marlén Gubsch Stefan Halle Alexandra M. Klein Ilona Kertscher Annely Kuu Markus Lange Xavier Le Roux Sebastian T. Meyer Varvara D. Migunova Alexandru Milcu Pascal A. Niklaus Yvonne Oelmann Esther Pašalić Jana S. Petermann Franck Poly Tanja Rottstock Alexander C. W. Sabais Christoph Scherber Michael Scherer-Lorenzen Stefan Scheu Sibylle Steinbeiss Guido Schwichtenberg Vicky Temperton Teja Tscharntke Winfried Voigt Wolfgang Wilcke Christian Wirth Bernhard Schmid 《Oecologia》2013,173(1):223-237
In order to predict which ecosystem functions are most at risk from biodiversity loss, meta-analyses have generalised results from biodiversity experiments over different sites and ecosystem types. In contrast, comparing the strength of biodiversity effects across a large number of ecosystem processes measured in a single experiment permits more direct comparisons. Here, we present an analysis of 418 separate measures of 38 ecosystem processes. Overall, 45 % of processes were significantly affected by plant species richness, suggesting that, while diversity affects a large number of processes not all respond to biodiversity. We therefore compared the strength of plant diversity effects between different categories of ecosystem processes, grouping processes according to the year of measurement, their biogeochemical cycle, trophic level and compartment (above- or belowground) and according to whether they were measures of biodiversity or other ecosystem processes, biotic or abiotic and static or dynamic. Overall, and for several individual processes, we found that biodiversity effects became stronger over time. Measures of the carbon cycle were also affected more strongly by plant species richness than were the measures associated with the nitrogen cycle. Further, we found greater plant species richness effects on measures of biodiversity than on other processes. The differential effects of plant diversity on the various types of ecosystem processes indicate that future research and political effort should shift from a general debate about whether biodiversity loss impairs ecosystem functions to focussing on the specific functions of interest and ways to preserve them individually or in combination. 相似文献
107.
Ludovic D'Auria Marisa Fenaux Paulina Aleksandrowicz Patrick Van Der Smissen Christophe Chantrain Christiane Vermylen Miikka Vikkula Pierre J. Courtoy Donatienne Tyteca 《Journal of lipid research》2013,54(4):1066-1076
Micrometric membrane lipid segregation is controversial. We addressed this issue in attached erythrocytes and found that fluorescent boron dipyrromethene (BODIPY) analogs of glycosphingolipids (GSLs) [glucosylceramide (BODIPY-GlcCer) and monosialotetrahexosylganglioside (GM1BODIPY)], sphingomyelin (BODIPY-SM), and phosphatidylcholine (BODIPY-PC inserted into the plasma membrane spontaneously gathered into distinct submicrometric domains. GM1BODIPY domains colocalized with endogenous GM1 labeled by cholera toxin. All BODIPY-lipid domains disappeared upon erythrocyte stretching, indicating control by membrane tension. Minor cholesterol depletion suppressed BODIPY-SM and BODIPY-PC but preserved BODIPY-GlcCer domains. Each type of domain exchanged constituents but assumed fixed positions, suggesting self-clustering and anchorage to spectrin. Domains showed differential association with 4.1R versus ankyrin complexes upon antibody patching. BODIPY-lipid domains also responded differentially to uncoupling at 4.1R complexes [protein kinase C (PKC) activation] and ankyrin complexes (in spherocytosis, a membrane fragility disease). These data point to micrometric compartmentation of polar BODIPY-lipids modulated by membrane tension, cholesterol, and differential association to the two nonredundant membrane:spectrin anchorage complexes. Micrometric compartmentation might play a role in erythrocyte membrane deformability and fragility. 相似文献
108.
Emmanuelle Stoetzel Christiane Denys Jacques Michaux Sabrina Renaud 《Biological journal of the Linnean Society. Linnean Society of London》2013,109(3):599-621
North Africa is an intricate biogeographical region at the crossroads of immigration waves from tropical Africa and Asia. Species confined between various barriers (Atlas Mountains, arid environments such as the Sahara in the south, water masses such as the Mediterranean Sea in the north, and the Atlantic Ocean in the west) were generally forced to adapt locally to environmental changes instead of tracking their habitat by shifting their distribution area. The present study aims at providing first insight into the evolution of the genus Mus, and more specifically of the western Mediterranean species Mus spretus in this area. The study relies on the abundant Late Pleistocene and Middle Holocene fossil assemblage from the El Harhoura 2 cave (Rabat‐Témara, Morocco). This exceptional record was studied using geometric morphometrics applied to first upper and lower molars, constituting the most informative and best preserved fossil remains for such small rodents. Two main issues were addressed. (1) Geometric morphometrics was used to clarify taxonomic status and phylogenetic relationships among fossil and modern species in this area. Morphometric analysis revealed good discrimination of most modern and fossil species but failed to document intermediate forms tracing anagenetic evolution. Not mutually exclusive, the occurrence of complex processes of morphological evolution in this genus such as parallel evolution and the action of stabilizing selection may make it difficult to translate patterns of morphological evolution into phylogenetic conclusions. (2) The record was shown to document a sequence of intraspecific evolution of M. spretus. The morphology of the molars through the fossil record of El Harhoura 2 was surprisingly stable despite extensive modern variation. The limited temporal variation largely failed to correlate to palaeoenvironmental proxies. The mouse fossil record at El Harhoura 2 thus presents an intriguing case of morphological stasis despite extensive environmental changes. This long‐term stability may have been recently perturbed by anthropogenic factors including landscape changes and introduction of various competitors and predators, leading to a size reduction. © 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2013, 109 , 599–621. 相似文献
109.
Background
Continuing efforts in development of non-invasive prenatal genetic tests have focused on the isolation of fetal nucleated red blood cells (NRBCs) from maternal blood for decades. Because no fetal cell-specific antibody has been described so far, the present study focused on the development of monoclonal antibodies (mAbs) to antigens that are expressed exclusively on fetal NRBCs.Methods: Mice were immunized with fetal erythroid cell membranes and hybridomas screened for Abs using a multi-parameter fluorescence-activated cell sorting (FACS). Selected mAbs were evaluated by comparative FACS analysis involving Abs known to bind erythroid cell surface markers (CD71, CD36, CD34), antigen-i, galactose, or glycophorin-A (GPA). Specificity was further confirmed by extensive immunohistological and immunocytological analyses of NRBCs from umbilical cord blood and fetal and adult cells from liver, bone marrow, peripheral blood, and lymphoid tissues.Results: Screening of 690 hybridomas yielded three clones of which Abs from 4B8 and 4B9 clones demonstrated the desired specificity for a novel antigenic structure expressed on fetal erythroblast cell membranes. The antigenic structure identified is different from known surface markers (CD36, CD71, GPA, antigen-i, and galactose), and is not present on circulating adult erythroid cells, except for occasional detectability in adult bone marrow cells.Conclusions:The new mAbs specifically bind the same or highly overlapping epitopes of a surface antigen that is almost exclusively expressed on fetal erythroid cells. The high specificity of the mAbs should facilitate development of simple methods for reliable isolation of fetal NRBCs and their use in non-invasive prenatal diagnosis of fetal genetic status. 相似文献110.
Christiane Baumert Marianne Günthel Sören Krawczyk Marc Hemmer Tom Wersig Andreas Langner Joséf Molnár Hermann Lage Andreas Hilgeroth 《Bioorganic & medicinal chemistry》2013,21(1):166-177
Novel series of N-benzyl 1,4-dihydropyridines have been prepared by facile syntheses. All relevant substituents of the molecular scaffold have been varied. The resulting compounds were biologically evaluated as P-glycoprotein (P-gp) inhibitors. Substitutions of the N-benzyl residue favour biological activity beside respective 3-ester functions. Most active compounds were further evaluated as multidrug resistance (MDR) modulators to restore the cytotoxic properties of varying daunorubicin applications. 相似文献