全文获取类型
收费全文 | 2148篇 |
免费 | 137篇 |
专业分类
2285篇 |
出版年
2023年 | 7篇 |
2022年 | 22篇 |
2021年 | 44篇 |
2020年 | 31篇 |
2019年 | 35篇 |
2018年 | 54篇 |
2017年 | 27篇 |
2016年 | 68篇 |
2015年 | 100篇 |
2014年 | 95篇 |
2013年 | 166篇 |
2012年 | 182篇 |
2011年 | 166篇 |
2010年 | 97篇 |
2009年 | 93篇 |
2008年 | 138篇 |
2007年 | 124篇 |
2006年 | 123篇 |
2005年 | 99篇 |
2004年 | 111篇 |
2003年 | 97篇 |
2002年 | 87篇 |
2001年 | 22篇 |
2000年 | 12篇 |
1999年 | 14篇 |
1998年 | 25篇 |
1997年 | 14篇 |
1996年 | 19篇 |
1995年 | 13篇 |
1994年 | 18篇 |
1993年 | 23篇 |
1992年 | 14篇 |
1991年 | 13篇 |
1990年 | 20篇 |
1989年 | 4篇 |
1988年 | 10篇 |
1987年 | 5篇 |
1986年 | 4篇 |
1985年 | 16篇 |
1984年 | 7篇 |
1983年 | 7篇 |
1982年 | 7篇 |
1981年 | 11篇 |
1980年 | 4篇 |
1979年 | 10篇 |
1978年 | 7篇 |
1975年 | 3篇 |
1974年 | 4篇 |
1971年 | 2篇 |
1968年 | 2篇 |
排序方式: 共有2285条查询结果,搜索用时 0 毫秒
61.
62.
Absolute Configuration Assignment of a Paraconic Acid Derivative via Vibrational Circular Dichroism Spectroscopy and Density Functional Theory Calculation 下载免费PDF全文
Sara Meninno Paola Rizzo Sergio Abbate Giovanna Longhi Giuseppe Mazzeo Guglielmo Monaco Alessandra Lattanzi Riccardo Zanasi 《Chirality》2016,28(2):110-115
Density functional theory calculation of the vibrational circular dichroism spectrum was used to assign the absolute configuration of an all‐carbon quaternary β‐stereocenter of a γ‐butyrolactone recently synthesized through an asymmetric organocatalytic tandem aldol/lactonization sequence. Comparison with the experimental spectrum is satisfactory, on account of the fact that spectroscopic features are weak due to the presence of multiple conformers. As a result, the (R) absolute configuration was assigned to the (+) optical isomer. Chirality 28:110–115, 2016. © 2015 Wiley Periodicals, Inc. 相似文献
63.
Giovanna Poce Robert H. Bates Salvatore Alfonso Martina Cocozza Giulio Cesare Porretta Lluís Ballell Joaquin Rullas Fátima Ortega Alessandro De Logu Emanuela Agus Valentina La Rosa Maria Rosalia Pasca Edda De Rossi Baojie Wae Scott G. Franzblau Fabrizio Manetti Maurizio Botta Mariangela Biava 《PloS one》2013,8(2)
1,5-Diphenyl pyrroles were previously identified as a class of compounds endowed with high in vitro efficacy against M. tuberculosis. To improve the physical chemical properties and drug-like parameters of this class of compounds, a medicinal chemistry effort was undertaken. By selecting the optimal substitution patterns for the phenyl rings at N1 and C5 and by replacing the thiomorpholine moiety with a morpholine one, a new series of compounds was produced. The replacement of the sulfur with oxygen gave compounds with lower lipophilicity and improved in
vitro microsomal stability. Moreover, since the parent compound of this family has been shown to target MmpL3, mycobacterial mutants resistant to two compounds have been isolated and characterized by sequencing the mmpL3 gene; all the mutants showed point mutations in this gene. The best compound identified to date was progressed to dose-response studies in an acute murine TB infection model. The resulting ED99 of 49 mg/Kg is within the range of commonly employed tuberculosis drugs, demonstrating the potential of this chemical series. The in vitro and in vivo target validation evidence presented here adds further weight to MmpL3 as a druggable target of interest for anti-tubercular drug discovery. 相似文献
64.
Diego Bucci Giovanna Galeati Elisa Giaretta Carlo Tamanini Marcella Spinaci 《Reproductive biology》2013,13(4):341-343
Sex-sorting damages spermatozoa function, shortening their lifespan and fertility. This study used an immunofluorescence technique to investigate the effect of sex-sorting on the localization of glucose transporters (GLUTs) in boar spermatozoa. GLUTs are trans-membrane proteins responsible for glucose transport within cells. Distribution of GLUTs on sperm cells was similar in unsorted and sex-sorted semen, suggesting that the flow cytometric sex-sorting process did not affect the sperm energy apparatus. 相似文献
65.
Maria Giovanna Riparbelli Romano Dallai Giuliano Callaini 《Biology of the cell / under the auspices of the European Cell Biology Organization》1993,78(3):223-227
Rhodamine phalloidin-staining was used to study the organization of the cortical actin cytoskeleton of the early Ceratitis capitata embryo. The dynamics of the actin aggregates and their changes in distribution during the formation of the syncytial blastoderm, were followed in detail. It was found that these aggregates formed a shell-like cluster around the interphase nuclei, and concentrated toward the poles of the mitotic apparatus when the nuclei divided. Laser scanning confocal microscopy revealed that aggregates not clustered at the poles of the mitotic apparatus were closely associated with fine fibers of a dense cytoplasmic network of actin filaments. 相似文献
66.
PJ Dutton LK Warrander SA Roberts G Bernatavicius LM Byrd D Gaze J Kroll RL Jones CP Sibley JF Frøen AE Heazell 《PloS one》2012,7(7):e39784
Background
Maternal perception of reduced fetal movement (RFM) is associated with increased risk of stillbirth and fetal growth restriction (FGR). RFM is thought to represent fetal compensation to conserve energy due to insufficient oxygen and nutrient transfer resulting from placental insufficiency.Objective
To identify predictors of poor perinatal outcome after maternal perception of reduced fetal movements (RFM).Design
Prospective cohort study.Methods
305 women presenting with RFM after 28 weeks of gestation were recruited. Demographic factors and clinical history were recorded and ultrasound performed to assess fetal biometry, liquor volume and umbilical artery Doppler. A maternal serum sample was obtained for measurement of placentally-derived or modified proteins including: alpha fetoprotein (AFP), human chorionic gonadotrophin (hCG), human placental lactogen (hPL), ischaemia-modified albumin (IMA), pregnancy associated plasma protein A (PAPP-A) and progesterone. Factors related to poor perinatal outcome were determined by logistic regression.Results
22.1% of pregnancies ended in a poor perinatal outcome after RFM. The most common complication was small-for-gestational age infants. Pregnancy outcome after maternal perception of RFM was related to amount of fetal activity while being monitored, abnormal fetal heart rate trace, diastolic blood pressure, estimated fetal weight, liquor volume, serum hCG and hPL. Following multiple logistic regression abnormal fetal heart rate trace (Odds ratio 7.08, 95% Confidence Interval 1.31–38.18), (OR) diastolic blood pressure (OR 1.04 (95% CI 1.01–1.09), estimated fetal weight centile (OR 0.95, 95% CI 0.94–0.97) and log maternal serum hPL (OR 0.13, 95% CI 0.02–0.99) were independently related to pregnancy outcome. hPL was related to placental mass.Conclusion
Poor perinatal outcome after maternal perception of RFM is closely related to factors which are connected to placental dysfunction. Novel tests of placental function and associated fetal response may provide improved means to detect fetuses at greatest risk of poor perinatal outcome after RFM. 相似文献67.
Sara Benedetti Pia Bernasconi Enrico Bertini Elena Biagini Giuseppe Boriani Cristina Capanni Nicola Carboni Giovanna Cenacchi Marta Columbaro Monica D’Adamo Adele D’Amico Maria Rosaria D’Apice Marianna Fontana Alessandra Gambineri Giovanna Lattanzi Rocco Liguori Nadir M Maraldi Laura Mazzanti Eugenio Mercuri Tiziana Mongini Lucia O Morandi Iria Neri Giovanni Nigro Giuseppe Novelli Michela Ortolani Renato Pasquali Antonella Pini Stefania Petrini Luisa Politano Stefano Previtali Lisa Pucci Claudio Rapezzi Giulia Ricci Carmelo Rodolico Paolo Sbraccia Emanuela Scarano Gabriele Siciliano Stefano Squarzoni Antonio Toscano Liliana Vercelli Matteo Ziacchi 《Orphanet journal of rare diseases》2012,7(1):1-3
The need for a collaborative approach to complex inherited diseases collectively referred to as laminopathies, encouraged Italian researchers, geneticists, physicians and patients to join in the Italian Network for Laminopathies, in 2009. Here, we highlight the advantages and added value of such a multidisciplinary effort to understand pathogenesis, clinical aspects and try to find a cure for Emery-Dreifuss muscular dystrophy, Mandibuloacral dysplasia, Hutchinson-Gilford Progeria and forms of lamin-linked cardiomyopathy, neuropathy and lipodystrophy. 相似文献
68.
69.
A taxonomic survey of lactic acid bacteria isolated from wheat (Triticum durum) kernels and non-conventional flours 总被引:2,自引:0,他引:2
Corsetti A Settanni L Chaves López C Felis GE Mastrangelo M Suzzi G 《Systematic and applied microbiology》2007,30(7):561-571
In order to explore the correspondence between raw material- and mature sourdough-lactic acid bacterial (LAB) communities, 59 Italian wheat (Triticum durum) grain samples, one bran and six non-conventional flour samples were analyzed through a culture-dependent approach. The highest cell count by an agar medium specific for LAB was 2.16 log CFU/g. From about 2300 presumptive LAB (Gram-positive and catalase-negative) colonies collected, a total of 356 isolates were subjected to identification by a genetic polyphasic strategy consisting of RAPD-PCR analysis, partial 16S rRNA gene sequencing, species-specific and multiplex PCRs. The isolates were recognized as 137 strains belonging to Aerococcus, Enterococcus, Lactobacillus, Lactococcus and Pediococcus genera and a phylogram based on partial 16S rRNA genes was constructed. The species most frequently found were Enterococcus faecium, Enterococcus mundtii and Lactobacillus graminis, which are not generally reported to be typical in mature sourdoughs. 相似文献
70.
The COP9 signalosome: more than a protease 总被引:1,自引:0,他引:1
The COP9 signalosome (CSN) is a conserved protein complex that functions in the ubiquitin-proteasome pathway. After two decades of research, we now know that the CSN is a multi-subunit protease that regulates the activity of cullin-RING ligase (CRL) families of ubiquitin E3 complexes. The CSN is rapidly emerging as a key player in the DNA-damage response, cell-cycle control and gene expression. The independent functions of CSN5 (also known as JAB1) add to the complexity of the CSN machinery. Here, we provide an updated view of the structure, functions and regulation of this protein complex. 相似文献