全文获取类型
收费全文 | 4339篇 |
免费 | 382篇 |
国内免费 | 2篇 |
出版年
2023年 | 13篇 |
2022年 | 26篇 |
2021年 | 78篇 |
2020年 | 58篇 |
2019年 | 70篇 |
2018年 | 96篇 |
2017年 | 80篇 |
2016年 | 131篇 |
2015年 | 198篇 |
2014年 | 206篇 |
2013年 | 344篇 |
2012年 | 353篇 |
2011年 | 335篇 |
2010年 | 222篇 |
2009年 | 187篇 |
2008年 | 285篇 |
2007年 | 297篇 |
2006年 | 276篇 |
2005年 | 250篇 |
2004年 | 206篇 |
2003年 | 213篇 |
2002年 | 220篇 |
2001年 | 47篇 |
2000年 | 36篇 |
1999年 | 52篇 |
1998年 | 57篇 |
1997年 | 28篇 |
1996年 | 34篇 |
1995年 | 31篇 |
1994年 | 37篇 |
1993年 | 26篇 |
1992年 | 26篇 |
1991年 | 12篇 |
1990年 | 21篇 |
1989年 | 18篇 |
1988年 | 15篇 |
1987年 | 10篇 |
1986年 | 13篇 |
1985年 | 6篇 |
1984年 | 11篇 |
1983年 | 5篇 |
1982年 | 11篇 |
1981年 | 10篇 |
1979年 | 8篇 |
1978年 | 8篇 |
1977年 | 10篇 |
1976年 | 8篇 |
1974年 | 6篇 |
1972年 | 6篇 |
1971年 | 5篇 |
排序方式: 共有4723条查询结果,搜索用时 31 毫秒
991.
Pascal Audet Céline Paquin Christophe Lacroix 《Applied microbiology and biotechnology》1988,29(1):11-18
Summary A cell entrapment process using -carrageenan — locust bean gum gel is presented. Streptococcus thermophilus, Lactobacillus bulgaricus and S. lactis were immobilized in small gel beads (0.5–1.0 mm and 1.0–2.0 mm diameter) and fermentations in bench bioreactors were conducted. Viability of entrapped cells, lactose utilization, lactic acid production and cell release rates were measured during fermentation. The procedure was effective for S. thermophilus, L. bulgaricus and S. lactis, and the viability of these bacteria remained very high throughout entrapment steps and subsequent storage. Bead diameter influenced the fermentation rate: smaller beads (0.5–1.0 mm) permitted an increase in release rates, lactose utilization and acid production by entrapped cells, approximating values attained with free cells. 相似文献
992.
993.
Roger Le Verge Pascal Le Corre Franois Chevanne Michle De De Maindreville Daniel Royer Jean Levy 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》1992,574(2)
The existence of at least two metabolites of yohimbine (YO) in humans is demonstrated. Combined high-performance liquid chromatographic (HPLC), NMR and mass spectral analyses permitted them to be identified as hydroxylated metabolites at the C-10 and C-11 positions. A normal-phase HPLC method allowing the simultaneous determination of YO and its main metabolite, 11-hydroxyyohimbine (11-OHYO), in biological samples is described. This assay was performed using a LiChrosorb Si 60 column and a mobile phase consisting of 0.02 M sodium acetate (pH 5)—methanol (5:95, v/v) at a flow-rate of 1 ml/min. Detection was achieved by a fluorimetric method (excitation at 280 nm and emission at 320 nm). The extraction yields of YO, 10-OHYO and 11-OHYO from plasma were 91.8, 45.3 and 17.8%, respectively, and their respective within-day reproducibilities were 3.8, 1.4 and 5.9%. The between-day reproducibility for YO at the concentrations of 1 and 10 ng/ml were 8.9 and 6.4%, respectively. The accuracy of the method for YO at concentrations of 1 and 10 ng/ml were 5.1 and 2.3%, respectively. The limits of determination of YO, 10-OHYO and 11-OHYO were 0.1, 0.5 and 1 ng/ml, respectively. The method was used in bioavailability study of YO following oral and intravenous administration in humans. 相似文献
994.
The T-6b gene of Agrobacterium tumefaciens strain Tm4 induces tumours on Nicotiana rustica by an as yet unknown mechanism. These tumours cannot be regenerated into normal plants. To study the effect of the T-6b gene product on normal plant cells, the T-6b gene was placed under control of the Drosophila melanogaster hsp70 heat-shock promoter and introduced into N. rustica. Progeny of an hsp70-T-6b transformant developed into normal plants. The inducibility of the hsp70-T-6b construct was shown by northern analysis and by heat-shock-dependent growth alterations on the level of whole seedlings. Upon wounding at normal temperature conditions hsp70-T-6b plants formed small tumours on leaves and stems. Grafts between transformed plants and normal plants led to a wound callus which remained limited to transformed tissues, indicating that the T-6b gene product does not diffuse. Protoplasts of hsp70-T-6b plants divided in the same way as control protoplasts under standard culture conditions. However, when protoplast cultures were started in the absence of hormones, normal cells rapidly lost their sensitivity towards hormones, whereas hsp70-T-6b cells remained sensitive for a significantly longer period. Thus, the T-6b gene product alters hormone sensitivity during the initial phases of protoplast culture. 相似文献
995.
Marie-Pierre Dorthu Suzanne Remy Marie-Rose Michel-Wolwertz Laurence Colleaux Didier Breyer Marie-Claire Beckers Serge Englebert Claire Duyckaerts Francis E. Sluse René F. Matagne 《Plant molecular biology》1992,18(4):759-772
Eight respiratory-deficient mutants ofChlamydomonas reinhardtii have been isolated after mutagenic treatment with acriflavine or ethidium bromide. They are characterized by their inability to grow or their very reduced growth under heterotrophic conditions. One mutation (Class III) is of nuclear origin whereas the seven remaining mutants (Classes I and II) display a predominantly paternalmt
- inheritance, typical of mutations residing in the mitochondrial DNA. Biochemical analysis has shown that all mutants are deficient in the cyanide-sensitive cytochrome pathway of the respiration whereas the alternative pathway is still functional. Measurements of complexes II + III (antimycin-sensitive succinate-cytochromec oxido-reductase) and complex IV (cytochromec oxidase) activities allowed to conclude that six mutations have to be localized in the mitochondrial apocytochromeb (COB) gene, one in the mitochondrial cytochrome oxidase subunit I (COI) gene and one in a nuclear gene encoding a component of the cytochrome oxidase complex. By using specific probes, we have moreover demonstrated that five mutants (Class II mutants) contain mitochondrial DNA molecules deleted in the terminal end containing the COB gene and the telomeric region; they also possess dimeric molecules resulting from end-to-end junctions of deleted monomers. The two other mitochondrial mutants (Class I) have no detectable gross alteration. Class I and Class II mutants can also be distinguished by the pattern of transmission of the mutation in crosses.Anin vivo staining test has been developed to identify rapidly the mutants impaired in cyanide-sensitive respiration. 相似文献
996.
Synthetic CpG oligonucleotides induce a genetic profile ameliorating murine myocardial I/R injury 下载免费PDF全文
Tobias Hilbert Paul Markowski Stilla Frede Olaf Boehm Pascal Knuefermann Georg Baumgarten Andreas Hoeft Sven Klaschik 《Journal of cellular and molecular medicine》2018,22(7):3397-3407
We previously demonstrated that pre‐conditioning with CpG oligonucleotide (ODN) 1668 induces quick up‐regulation of gene expression 3 hours post‐murine myocardial ischaemia/reperfusion (I/R) injury, terminating inflammatory processes that sustain I/R injury. Now, performing comprehensive microarray and biocomputational analyses, we sought to further enlighten the “black box” beyond these first 3 hours. C57BL/6 mice were pretreated with either CpG 1668 or with control ODN 1612, respectively. Sixteen hours later, myocardial ischaemia was induced for 1 hour in a closed‐chest model, followed by reperfusion for 24 hours. RNA was extracted from hearts, and labelled cDNA was hybridized to gene microarrays. Data analysis was performed with BRB ArrayTools and Ingenuity Pathway Analysis. Functional groups mediating restoration of cellular integrity were among the top up‐regulated categories. Genes known to influence cardiomyocyte survival were strongly induced 24 hours post‐I/R. In contrast, proinflammatory pathways were down‐regulated. Interleukin‐10, an upstream regulator, suppressed specifically selected proinflammatory target genes at 24 hours compared to 3 hours post‐I/R. The IL1 complex is supposed to be one regulator of a network increasing cardiovascular angiogenesis. The up‐regulation of numerous protective pathways and the suppression of proinflammatory activity are supposed to be the genetic correlate of the cardioprotective effects of CpG 1668 pre‐conditioning. 相似文献
997.
Half the story: Thermal effects on within‐host infectious disease progression in a warming climate 下载免费PDF全文
Alexander Stewart Pascal I. Hablützel Martha Brown Hayley V. Watson Sophie Parker‐Norman Anya V. Tober Anna G. Thomason Ida M. Friberg Joseph A. Jackson 《Global Change Biology》2018,24(1):371-386
Immune defense is temperature dependent in cold‐blooded vertebrates (CBVs) and thus directly impacted by global warming. We examined whether immunity and within‐host infectious disease progression are altered in CBVs under realistic climate warming in a seasonal mid‐latitude setting. Going further, we also examined how large thermal effects are in relation to the effects of other environmental variation in such a setting (critical to our ability to project infectious disease dynamics from thermal relationships alone). We employed the three‐spined stickleback and three ecologically relevant parasite infections as a “wild” model. To generate a realistic climatic warming scenario we used naturalistic outdoors mesocosms with precise temperature control. We also conducted laboratory experiments to estimate thermal effects on immunity and within‐host infectious disease progression under controlled conditions. As experimental readouts we measured disease progression for the parasites and expression in 14 immune‐associated genes (providing insight into immunophenotypic responses). Our mesocosm experiment demonstrated significant perturbation due to modest warming (+2°C), altering the magnitude and phenology of disease. Our laboratory experiments demonstrated substantial thermal effects. Prevailing thermal effects were more important than lagged thermal effects and disease progression increased or decreased in severity with increasing temperature in an infection‐specific way. Combining laboratory‐determined thermal effects with our mesocosm data, we used inverse modeling to partition seasonal variation in Saprolegnia disease progression into a thermal effect and a latent immunocompetence effect (driven by nonthermal environmental variation and correlating with immune gene expression). The immunocompetence effect was large, accounting for at least as much variation in Saprolegnia disease as the thermal effect. This suggests that managers of CBV populations in variable environments may not be able to reliably project infectious disease risk from thermal data alone. Nevertheless, such projections would be improved by primarily considering prevailing thermal effects in the case of within‐host disease and by incorporating validated measures of immunocompetence. 相似文献
998.
Phimpha Paboriboune Thomas Vial Philavanh Sitbounlang Stéphane Bertani Christian Trépo Paul Dény Francois-Xavier Babin Nicolas Steenkeste Pascal Pineau Eric Deharo 《中国病毒学》2018,33(4):295-303
Hepatitis C virus(HCV) is a global health concern, notably in Southeast Asia, and in Laos the presentation of the HCVinduced liver disease is poorly known. Our objective was thus to describe a comprehensive HCV infection pattern in order to guide national health policies. A study on a group of 1765 patients formerly diagnosed by rapid test in health centres was conducted at the Centre of Infectiology Lao Christophe Merieux in Vientiane. The demographic information of patients,their infection status(viral load: VL), liver function(aminotransferases) and treatments were analysed. Results showed that gender distribution of infected people was balanced; with median ages of 53.8 for men and 51.6 years for women(13–86 years). The majority of patients(72%) were confirmed positive(VL [ 50 IU/mL) and 28% of them had high VL([ 6 log10). About 23% of patients had level of aminotransferases indicative of liver damage([ 40 IU/m L); but less than20% of patients received treatment. Patients rarely received a second sampling or medical imaging. The survey also showed that cycloferon, pegylated interferon and ribavirin were the drugs prescribed preferentially by the medical staff,without following any international recommendations schemes. In conclusion, we recommend that a population screening policy and better management of patients should be urgently implemented in the country, respecting official guidelines.However, the cost of biological analysis and treatment are significant barriers that must be removed. Public health resolutions should be immediately enforced in the perspective of meeting the WHO HCV elimination deadline by 2030. 相似文献
999.
Microparticle miRNAs as Biomarkers of Vascular Function and Inflammation Response to Aerobic Exercise in Obesity? 下载免费PDF全文
Saloua Dimassi Esma Karkeni Pascal Laurant Zouhair Tabka Jean‐François Landrier Catherine Riva 《Obesity (Silver Spring, Md.)》2018,26(10):1584-1593