全文获取类型
收费全文 | 2432篇 |
免费 | 335篇 |
出版年
2016年 | 32篇 |
2015年 | 66篇 |
2014年 | 60篇 |
2013年 | 79篇 |
2012年 | 94篇 |
2011年 | 129篇 |
2010年 | 62篇 |
2009年 | 69篇 |
2008年 | 94篇 |
2007年 | 82篇 |
2006年 | 74篇 |
2005年 | 93篇 |
2004年 | 103篇 |
2003年 | 66篇 |
2002年 | 78篇 |
2001年 | 73篇 |
2000年 | 76篇 |
1999年 | 47篇 |
1998年 | 29篇 |
1997年 | 32篇 |
1996年 | 27篇 |
1995年 | 28篇 |
1994年 | 25篇 |
1993年 | 20篇 |
1992年 | 72篇 |
1991年 | 60篇 |
1990年 | 54篇 |
1989年 | 57篇 |
1988年 | 53篇 |
1987年 | 45篇 |
1986年 | 59篇 |
1985年 | 49篇 |
1984年 | 57篇 |
1983年 | 35篇 |
1982年 | 35篇 |
1981年 | 26篇 |
1980年 | 29篇 |
1979年 | 41篇 |
1978年 | 38篇 |
1977年 | 42篇 |
1975年 | 31篇 |
1974年 | 41篇 |
1973年 | 26篇 |
1972年 | 42篇 |
1971年 | 39篇 |
1970年 | 34篇 |
1969年 | 37篇 |
1968年 | 33篇 |
1967年 | 22篇 |
1966年 | 20篇 |
排序方式: 共有2767条查询结果,搜索用时 15 毫秒
1.
Increased urine podocyte‐associated messenger RNAs in severe obesity are evidence of podocyte injury 下载免费PDF全文
2.
Joshua M. Thurman Maria Wong Brandon Renner Ashley Frazer-Abel Patricia C. Giclas Melanie S. Joy Diana Jalal Milena K. Radeva Jennifer Gassman Debbie S. Gipson Frederick Kaskel Aaron Friedman Howard Trachtman 《PloS one》2015,10(9)
Background
Recent pre-clinical studies have shown that complement activation contributes to glomerular and tubular injury in experimental FSGS. Although complement proteins are detected in the glomeruli of some patients with FSGS, it is not known whether this is due to complement activation or whether the proteins are simply trapped in sclerotic glomeruli. We measured complement activation fragments in the plasma and urine of patients with primary FSGS to determine whether complement activation is part of the disease process.Study Design
Plasma and urine samples from patients with biopsy-proven FSGS who participated in the FSGS Clinical Trial were analyzed.Setting and Participants
We identified 19 patients for whom samples were available from weeks 0, 26, 52 and 78. The results for these FSGS patients were compared to results in samples from 10 healthy controls, 10 patients with chronic kidney disease (CKD), 20 patients with vasculitis, and 23 patients with lupus nephritis.Outcomes
Longitudinal control of proteinuria and estimated glomerular filtration rate (eGFR).Measurements
Levels of the complement fragments Ba, Bb, C4a, and sC5b-9 in plasma and urine.Results
Plasma and urine Ba, C4a, sC5b-9 were significantly higher in FSGS patients at the time of diagnosis than in the control groups. Plasma Ba levels inversely correlated with the eGFR at the time of diagnosis and at the end of the study. Plasma and urine Ba levels at the end of the study positively correlated with the level of proteinuria, the primary outcome of the study.Limitations
Limited number of patients with samples from all time-points.Conclusions
The complement system is activated in patients with primary FSGS, and elevated levels of plasma Ba correlate with more severe disease. Measurement of complement fragments may identify a subset of patients in whom the complement system is activated. Further investigations are needed to confirm our findings and to determine the prognostic significance of complement activation in patients with FSGS. 相似文献3.
Shai Efrati Haim Golan Yair Bechor Yifat Faran Shir Daphna-Tekoah Gal Sekler Gregori Fishlev Jacob N. Ablin Jacob Bergan Olga Volkov Mony Friedman Eshel Ben-Jacob Dan Buskila 《PloS one》2015,10(5)
BackgroundFibromyalgia Syndrome (FMS) is a persistent and debilitating disorder estimated to impair the quality of life of 2–4% of the population, with 9:1 female-to-male incidence ratio. FMS is an important representative example of central nervous system sensitization and is associated with abnormal brain activity. Key symptoms include chronic widespread pain, allodynia and diffuse tenderness, along with fatigue and sleep disturbance. The syndrome is still elusive and refractory. The goal of this study was to evaluate the effect of hyperbaric oxygen therapy (HBOT) on symptoms and brain activity in FMS.ConclusionsThe study provides evidence that HBOT can improve the symptoms and life quality of FMS patients. Moreover, it shows that HBOT can induce neuroplasticity and significantly rectify abnormal brain activity in pain related areas of FMS patients.
Trial Registration
ClinicalTrials.gov NCT01827683相似文献4.
5.
Viral activation of the coagulation cascade: molecular interactions at the surface of infected endothelial cells 总被引:10,自引:0,他引:10
Herpesviral infection of endothelial cells (ECs) induces arterial injury. We now demonstrate that such infection promoted enhanced monocyte-endothelial adhesion. Enhanced adhesion was blocked by monoclonal antibodies to the viral-encoded cell surface glycoprotein gC but not by antibodies to gD or gE. Adhesion was also blocked by treating ECs with specific thrombin inhibitors or by growing cells in prothrombin-depleted serum. We found that gC bound and promoted activation of factor X on infected ECs, thereby contributing to thrombin generation. Factor X also bound to transfected L cells that were induced to express gC. Cross-linking and immunoprecipitation studies demonstrated factor X-gC complex formation on the surface of these cells. We suggest that gC-dependent thrombin generation by herpes-infected endothelium may be an important mediator of vascular pathology during viral infection. 相似文献
6.
K Alston R C Robinson S S Park H V Gelboin F K Friedman 《The Journal of biological chemistry》1991,266(2):735-739
The quaternary structure of rat liver cytochrome P-450 within microsomal membranes from 3-methyl-cholanthrene-treated rats was examined by a novel chemical cross-linking-monoclonal antibody approach. Complex formation among the different forms of P-450 was probed by cross-linking of membrane proteins followed by immunopurification with a monoclonal antibody (mAb) to P-450c, the major 3-methylcholanthrene-inducible form. Subsequent immunoblot analysis of the immunopurified proteins with this mAb indicated that P-450c formed complexes with other microsomal proteins. Immunoblots with mAbs to different P-450s were carried out to identify the P-450s that were cross-linked to P-450c. This approach detected specific cross-linking of P-450c to P-450 2a. Immunoinhibition experiments suggest that P-450 2a further metabolizes the primary phenols produced by P-450c-catalyzed hydroxylation of benzo[a]pyrene. Complex formation among membrane-bound enzymes has implications for their catalytic efficiency and an approach combining cross-linking and monoclonal antibody-based characterization of cross-linked proteins will be useful for elucidating such membrane protein macrostructures. 相似文献
7.
8.
Reproductive timing is a key life‐history trait that impacts the pool of available mates, the environment experienced during flowering, and the expression of other traits through genetic covariation. Selection on phenology, and its consequences on other life‐history traits, has considerable implications in the context of ongoing climate change and shifting growing seasons. To test this, we grew field‐collected seed from the wildflower Mimulus guttatus in a greenhouse to assess the standing genetic variation for flowering time and covariation with other traits. We then created full‐sib families through phenological assortative mating and grew offspring in three photoperiod treatments representing seasonal variation in daylength. We find substantial quantitative genetic variation for the onset of flowering time, which covaried with vegetative traits. The assortatively‐mated offspring varied in their critical photoperiod by over two hours, so that families differed in their probability of flowering across treatments Allocation to flowering and vegetative growth changed across the daylength treatments, with consistent direction and magnitude of covariation among flowering time and other traits. Our results suggest that future studies of flowering time evolution should consider the joint evolution of correlated traits and shifting seasonal selection to understand how environmental variation influences life histories. 相似文献
9.
D D Monkovic W J VanDusen C J Petroski V M Garsky M K Sardana P Zavodszky A M Stern P A Friedman 《Biochemical and biophysical research communications》1992,189(1):233-241
An invertebrate alpha-ketoglutarate-dependent aspartyl/asparaginyl beta-hydroxylase, which posttranslationally hydroxylates specific aspartyl or asparaginyl residues within epidermal growth factor-like modules, was identified, partially purified and characterized. Preparations derived from two insect cell lines catalyzed the hydroxylation of the expected asparaginyl residue within a synthetic epidermal growth factor-like module. This activity was found to be similar to that of the purified mammalian aspartyl/asparaginyl beta-hydroxylase with respect to cofactor requirements, stereochemistry and substrate sequence specificity. Furthermore, recombinant human C1r, expressed in an insect cell-derived baculovirus expression system, was also found to be hydroxylated at the expected asparaginyl residue. Thus, these results establish the potential for invertebrate aspartyl/asparaginyl hydroxylation. Since several invertebrate proteins known to be required for proper embryonic development contain a putative consensus sequence that may be required for hydroxylation, the studies presented here provide the basis for further investigations concerned with identifying hydroxylated invertebrate proteins and determining their physiologic function. 相似文献
10.
Beata Matysioková Nicholas Friedman Lucia Turčoková Vladimír Remeš 《Journal of avian biology》2017,48(7):1015-1024
What is the tempo and mode of evolution – how fast and in what pattern do traits evolve – is a major question of evolutionary biology. Here we studied patterns of evolutionary change in visual and acoustic signals in Old World orioles. Since producing multiple signals may be costly, we also tested whether there was an evolutionary trade‐off between the elaboration of those two types of signals. We studied 30 Oriolus taxa using comparative methods and a recent molecular phylogeny. Morphology and plumage hue evolved comparatively slowly, whereas song evolved rapidly. Among individual feather patches, the evolutionary rate of color was slowest in primaries, which are critical for flapping flight, and fastest in patches exposed to observers (mantle and breast). Thus, primaries seem to be under functional constraint while the evolution of visually exposed patches is perhaps shaped by sexual selection. Song evolution was comparatively fast, but also attracted to a single optimum. This may be due to selection for signal efficacy, because all orioles inhabit similar forested habitats. Only color diversity was best fit by a speciational model: the biggest changes in coloration were concentrated at speciation events, thus perhaps linked to the evolution of species recognition. Our analysis did not reveal any evolutionary trade‐off between acoustic and visual signals, suggesting that the elaboration of visual and acoustic signals in the Old World orioles evolved independently. Our study shows that patterns of evolutionary change may be surprisingly complex even within a single clade of birds and thus further studies are needed to identify general patterns of signal macroevolution. 相似文献