全文获取类型
收费全文 | 2977篇 |
免费 | 156篇 |
出版年
2022年 | 18篇 |
2021年 | 30篇 |
2020年 | 19篇 |
2019年 | 33篇 |
2018年 | 44篇 |
2017年 | 45篇 |
2016年 | 79篇 |
2015年 | 111篇 |
2014年 | 111篇 |
2013年 | 207篇 |
2012年 | 212篇 |
2011年 | 193篇 |
2010年 | 121篇 |
2009年 | 115篇 |
2008年 | 184篇 |
2007年 | 183篇 |
2006年 | 182篇 |
2005年 | 164篇 |
2004年 | 150篇 |
2003年 | 138篇 |
2002年 | 127篇 |
2001年 | 29篇 |
2000年 | 22篇 |
1999年 | 28篇 |
1998年 | 25篇 |
1997年 | 32篇 |
1996年 | 27篇 |
1995年 | 28篇 |
1994年 | 23篇 |
1993年 | 29篇 |
1992年 | 28篇 |
1991年 | 25篇 |
1990年 | 27篇 |
1989年 | 16篇 |
1988年 | 24篇 |
1987年 | 19篇 |
1986年 | 17篇 |
1985年 | 17篇 |
1984年 | 29篇 |
1983年 | 25篇 |
1982年 | 21篇 |
1981年 | 18篇 |
1980年 | 20篇 |
1979年 | 21篇 |
1978年 | 23篇 |
1977年 | 12篇 |
1976年 | 10篇 |
1975年 | 11篇 |
1974年 | 11篇 |
1973年 | 12篇 |
排序方式: 共有3133条查询结果,搜索用时 15 毫秒
981.
The trace proteome of white-wine vinegar has been identified via capture with home-made combinatorial peptide ligand libraries under conditions mimicking reverse-phase capture, i.e. at pH 2.2 in presence of 0.1% trifluoroacetic acid. A total of 27 unique gene products have been identified, of which 10 specific of the database Vitis vinifera, 13 found in the general database Uniprot_viridiplantae and 4 in Swiss Prot_all entries. The most abundant species detected, on the basis of spectral counts, appears to be the whole genome shotgun sequence of line PN40024, scaffold_22 (a protein of the glycosyl hydrolase family). Curiously, up to the present, no information had been available on vinegar proteome. 相似文献
982.
Eller-Vainicher C Chiodini I Santi I Massarotti M Pietrogrande L Cairoli E Beck-Peccoz P Longhi M Galmarini V Gandolini G Bevilacqua M Grossi E 《PloS one》2011,6(11):e27277
Background
It is known that bone mineral density (BMD) predicts the fracture''s risk only partially and the severity and number of vertebral fractures are predictive of subsequent osteoporotic fractures (OF). Spinal deformity index (SDI) integrates the severity and number of morphometric vertebral fractures. Nowadays, there is interest in developing algorithms that use traditional statistics for predicting OF. Some studies suggest their poor sensitivity. Artificial Neural Networks (ANNs) could represent an alternative. So far, no study investigated ANNs ability in predicting OF and SDI. The aim of the present study is to compare ANNs and Logistic Regression (LR) in recognising, on the basis of osteoporotic risk-factors and other clinical information, patients with SDI≥1 and SDI≥5 from those with SDI = 0.Methodology
We compared ANNs prognostic performance with that of LR in identifying SDI≥1/SDI≥5 in 372 women with postmenopausal-osteoporosis (SDI≥1, n = 176; SDI = 0, n = 196; SDI≥5, n = 51), using 45 variables (44 clinical parameters plus BMD). ANNs were allowed to choose relevant input data automatically (TWIST-system-Semeion). Among 45 variables, 17 and 25 were selected by TWIST-system-Semeion, in SDI≥1 vs SDI = 0 (first) and SDI≥5 vs SDI = 0 (second) analysis. In the first analysis sensitivity of LR and ANNs was 35.8% and 72.5%, specificity 76.5% and 78.5% and accuracy 56.2% and 75.5%, respectively. In the second analysis, sensitivity of LR and ANNs was 37.3% and 74.8%, specificity 90.3% and 87.8%, and accuracy 63.8% and 81.3%, respectively.Conclusions
ANNs showed a better performance in identifying both SDI≥1 and SDI≥5, with a higher sensitivity, suggesting its promising role in the development of algorithm for predicting OF. 相似文献983.
Dunyo S Sirugo G Sesay S Bisseye C Njie F Adiamoh M Nwakanma D Diatta M Janha R Sisay Joof F Temple B Snell P Conway D Walton R Cheung YB Milligan P 《PloS one》2011,6(6):e17371
Background
Chlorproguanil-dapsone (Lapdap), developed as a low-cost antimalarial, was withdrawn in 2008 after concerns about safety in G6PD deficient patients. This trial was conducted in 2004 to evaluate the safety and effectiveness of CD and comparison with artemether-lumefantrine (AL) under conditions of routine use in G6PD normal and G6PD deficient patients with uncomplicated malaria in The Gambia. We also examined the effects of a common genetic variant that affects chlorproguanil metabolism on risk of treatment failure.Methods
1238 children aged 6 months to 10 years with uncomplicated malaria were randomized to receive CD or artemether-lumefantrine (AL) and followed for 28 days. The first dose was supervised, subsequent doses given unsupervised at home. G6PD genotype was determined to assess the interaction between treatment and G6PD status in their effects on anaemia. The main endpoints were clinical treatment failure by day 28, incidence of severe anaemia (Hb<5 g/dL), and haemoglobin concentration on day 3.Findings
One third of patients treated with AL, and 6% of patients treated with CD, did not complete their course of medication. 18% (109/595) of children treated with CD and 6.1% (36/587) with AL required rescue medication within 4 weeks, risk difference 12% (95%CI 8.9%–16%). 23 children developed severe anaemia (17 (2.9%) treated with CD and 6 (1.0%) with AL, risk difference 1.8%, 95%CI 0.3%–3.4%, P = 0.02). Haemoglobin concentration on day 3 was lower among children treated with CD than AL (difference 0.43 g/dL, 95% CI 0.24 to 0.62), and within the CD group was lower among those children who had higher parasite density at enrolment. Only 17 out of 1069 children who were typed were G6PD A- deficient, of these 2/9 treated with CD and 1/8 treated with AL developed severe anaemia. 5/9 treated with CD had a fall of 2 g/dL or more in haemoglobin concentration by day 3.Interpretation
AL was well tolerated and highly effective and when given under operational conditions despite poor adherence to the six-dose regimen. There were more cases of severe malaria and anaemia after CD treatment although G6PD deficiency was uncommon.Trial Registration
Clinicaltrials.gov NCT00118794相似文献984.
Orecchia A Scarponi C Di Felice F Cesarini E Avitabile S Mai A Mauro ML Sirri V Zambruno G Albanesi C Camilloni G Failla CM 《PloS one》2011,6(9):e24307
Histone deacetylases (HDAC) are key enzymes in the epigenetic control of gene expression. Recently, inhibitors of class I and class II HDAC have been successfully employed for the treatment of different inflammatory diseases such as rheumatoid arthritis, colitis, airway inflammation and asthma. So far, little is known so far about a similar therapeutic effect of inhibitors specifically directed against sirtuins, the class III HDAC. In this study, we investigated the expression and localization of endogenous sirtuins in primary human dermal microvascular endothelial cells (HDMEC), a cell type playing a key role in the development and maintenance of skin inflammation. We then examined the biological activity of sirtinol, a specific sirtuin inhibitor, in HDMEC response to pro-inflammatory cytokines. We found that, even though sirtinol treatment alone affected only long-term cell proliferation, it diminishes HDMEC inflammatory responses to tumor necrosis factor (TNF)α and interleukin (IL)-1β. In fact, sirtinol significantly reduced membrane expression of adhesion molecules in TNFã- or IL-1β-stimulated cells, as well as the amount of CXCL10 and CCL2 released by HDMEC following TNFα treatment. Notably, sirtinol drastically decreased monocyte adhesion on activated HDMEC. Using selective inhibitors for Sirt1 and Sirt2, we showed a predominant involvement of Sirt1 inhibition in the modulation of adhesion molecule expression and monocyte adhesion on activated HDMEC. Finally, we demonstrated the in vivo expression of Sirt1 in the dermal vessels of normal and psoriatic skin. Altogether, these findings indicated that sirtuins may represent a promising therapeutic target for the treatment of inflammatory skin diseases characterized by a prominent microvessel involvement. 相似文献
985.
Vitulo N Albiero A Forcato C Campagna D Dal Pero F Bagnaresi P Colaiacovo M Faccioli P Lamontanara A Šimková H Kubaláková M Perrotta G Facella P Lopez L Pietrella M Gianese G Doležel J Giuliano G Cattivelli L Valle G Stanca AM 《PloS one》2011,6(10):e26421
Wheat is one of the world's most important crops and is characterized by a large polyploid genome. One way to reduce genome complexity is to isolate single chromosomes using flow cytometry. Low coverage DNA sequencing can provide a snapshot of individual chromosomes, allowing a fast characterization of their main features and comparison with other genomes. We used massively parallel 454 pyrosequencing to obtain a 2x coverage of wheat chromosome 5A. The resulting sequence assembly was used to identify TEs, genes and miRNAs, as well as to infer a virtual gene order based on the synteny with other grass genomes. Repetitive elements account for more than 75% of the genome. Gene content was estimated considering non-redundant reads showing at least one match to ESTs or proteins. The results indicate that the coding fraction represents 1.08% and 1.3% of the short and long arm respectively, projecting the number of genes of the whole chromosome to approximately 5,000. 195 candidate miRNA precursors belonging to 16 miRNA families were identified. The 5A genes were used to search for syntenic relationships between grass genomes. The short arm is closely related to Brachypodium chromosome 4, sorghum chromosome 8 and rice chromosome 12; the long arm to regions of Brachypodium chromosomes 4 and 1, sorghum chromosomes 1 and 2 and rice chromosomes 9 and 3. From these similarities it was possible to infer the virtual gene order of 392 (5AS) and 1,480 (5AL) genes of chromosome 5A, which was compared to, and found to be largely congruent with the available physical map of this chromosome. 相似文献
986.
987.
Millioni R Tolin S Puricelli L Sbrignadello S Fadini GP Tessari P Arrigoni G 《PloS one》2011,6(5):e19603
Background
To date, the complexity of the plasma proteome exceeds the analytical capacity of conventional approaches to isolate lower abundance proteins that may prove to be informative biomarkers. Only complex multistep separation strategies have been able to detect a substantial number of low abundance proteins (<100 ng/ml). The first step of these protocols is generally the depletion of high abundance proteins by the use of immunoaffinity columns or, alternatively, the enrichment of by the use of solid phase hexapeptides ligand libraries.Methodology/Principal Findings
Here we present a direct comparison of these two approaches. Following either approach, the plasma sample was further fractionated by SCX chromatography and analyzed by RP-LC-MS/MS with a Q-TOF mass spectrometer. The depletion of the 20 most abundant plasma proteins allowed the identification of about 25% more proteins than those detectable following low abundance proteins enrichment. The two datasets are partially overlapping and the identified proteins belong to the same order of magnitude in terms of plasma concentration.Conclusions/Significance
Our results show that the two approaches give complementary results. However, the enrichment of low abundance proteins has the great advantage of obtaining much larger amount of material that can be used for further fractionations and analyses and emerges also as a cheaper and technically simpler approach. Collectively, these data indicate that the enrichment approach seems more suitable as the first stage of a complex multi-step fractionation protocol. 相似文献988.
Hypoglycemia is associated with increased risk of cardiovascular adverse clinical outcomes. There is evidence that impaired glucose tolerance (IGT) is associated with cardiovascular morbidity and mortality. Whether IGT individuals have asymptomatic hypoglycemia under real-life conditions that are related to early atherosclerosis is unknown. To this aim, we measured episodes of hypoglycemia during continuous interstitial glucose monitoring (CGM) and evaluated their relationship with early manifestation of vascular atherosclerosis in glucose tolerant and intolerant individuals. An oral glucose tolerance test (OGTT) was performed in 79 non-diabetic subjects. Each individual underwent continuous glucose monitoring for 72 h. Cardiovascular risk factors and ultrasound measurement of carotid intima-media thickness (IMT) were evaluated. IGT individuals had a worse cardiovascular risk profile, including higher IMT, and spent significantly more time in hypoglycemia than glucose-tolerant individuals. IMT was significantly correlated with systolic (r = 0.22; P = 0.05) and diastolic blood pressure (r = 0.28; P = 0.01), total (r = 0.26; P = 0.02) and LDL cholesterol (r = 0.27; P = 0.01), 2-h glucose (r = 0.39; P<0.0001), insulin sensitivity (r = −0.26; P = 0.03), and minutes spent in hypoglycemia (r = 0.45; P<0.0001). In univariate analyses adjusted for gender, minutes spent in hypoglycemia were significantly correlated with age (r = 0.26; P = 0.01), waist circumference (r = 0.33; P = 0.003), 2-h glucose (r = 0.58; P<0.0001), and 2-h insulin (r = 0.27; P = 0.02). In a stepwise multivariate regression analysis, the variables significantly associated with IMT were minutes spent in hypoglycemia (r2 = 0.252; P<0.0001), and ISI index (r2 = 0.089; P = 0.004), accounting for 34.1% of the variation. Episodes of hypoglycemia may be considered as a new potential cardiovascular risk factor for IGT individuals. 相似文献
989.
Morris GA Edwards DR Hill PC Wejse C Bisseye C Olesen R Edwards TL Gilbert JR Myers JL Stryjewski ME Abbate E Estevan R Hamilton CD Tacconelli A Novelli G Brunetti E Aaby P Sodemann M Østergaard L Adegbola R Williams SM Scott WK Sirugo G 《PloS one》2011,6(2):e16656
We examined whether polymorphisms in interleukin-12B (IL12B) associate with susceptibility to pulmonary tuberculosis (PTB) in two West African populations (from The Gambia and Guinea-Bissau) and in two independent populations from North and South America. Nine polymorphisms (seven SNPs, one insertion/deletion, one microsatellite) were analyzed in 321 PTB cases and 346 controls from Guinea-Bissau and 280 PTB cases and 286 controls from The Gambia. For replication we studied 281 case and 179 control African-American samples and 221 cases and 144 controls of European ancestry from the US and Argentina. First-stage single locus analyses revealed signals of association at IL12B 3′ UTR SNP rs3212227 (unadjusted allelic p = 0.04; additive genotypic p = 0.05, OR = 0.78, 95% CI [0.61–0.99]) in Guinea-Bissau and rs11574790 (unadjusted allelic p = 0.05; additive genotypic p = 0.05, OR = 0.76, 95% CI [0.58–1.00]) in The Gambia. Association of rs3212227 was then replicated in African-Americans (rs3212227 allelic p = 0.002; additive genotypic p = 0.05, OR = 0.78, 95% CI [0.61–1.00]); most importantly, in the African-American cohort, multiple significant signals of association (seven of the nine polymorphisms tested) were detected throughout the gene. These data suggest that genetic variation in IL12B, a highly relevant candidate gene, is a risk factor for PTB in populations of African ancestry, although further studies will be required to confirm this association and identify the precise mechanism underlying it. 相似文献
990.