全文获取类型
收费全文 | 796篇 |
免费 | 147篇 |
国内免费 | 4篇 |
专业分类
947篇 |
出版年
2023年 | 4篇 |
2022年 | 13篇 |
2021年 | 28篇 |
2020年 | 20篇 |
2019年 | 36篇 |
2018年 | 51篇 |
2017年 | 23篇 |
2016年 | 25篇 |
2015年 | 53篇 |
2014年 | 50篇 |
2013年 | 43篇 |
2012年 | 58篇 |
2011年 | 64篇 |
2010年 | 53篇 |
2009年 | 29篇 |
2008年 | 33篇 |
2007年 | 26篇 |
2006年 | 26篇 |
2005年 | 31篇 |
2004年 | 27篇 |
2003年 | 30篇 |
2002年 | 19篇 |
2001年 | 10篇 |
2000年 | 16篇 |
1999年 | 12篇 |
1997年 | 9篇 |
1996年 | 7篇 |
1994年 | 5篇 |
1993年 | 5篇 |
1992年 | 6篇 |
1991年 | 3篇 |
1990年 | 6篇 |
1989年 | 7篇 |
1988年 | 10篇 |
1987年 | 9篇 |
1986年 | 9篇 |
1985年 | 7篇 |
1984年 | 10篇 |
1983年 | 6篇 |
1982年 | 5篇 |
1981年 | 5篇 |
1980年 | 3篇 |
1979年 | 8篇 |
1977年 | 4篇 |
1976年 | 3篇 |
1975年 | 8篇 |
1974年 | 10篇 |
1973年 | 5篇 |
1970年 | 2篇 |
1968年 | 2篇 |
排序方式: 共有947条查询结果,搜索用时 15 毫秒
891.
Natriuretic peptides stimulate the cardiac sodium pump via NPR-C-coupled NOS activation 总被引:1,自引:0,他引:1
William M Hamilton EJ Garcia A Bundgaard H Chia KK Figtree GA Rasmussen HH 《American journal of physiology. Cell physiology》2008,294(4):C1067-C1073
Natriuretic peptides (NPs) and their receptors (NPRs) are expressed in the heart, but their effects on myocyte function are poorly understood. Because NPRs are coupled to synthesis of cGMP, an activator of the sarcolemmal Na(+)-K(+) pump, we examined whether atrial natriuretic peptide (ANP) regulates the pump. We voltage clamped rabbit ventricular myocytes and identified electrogenic Na(+)-K(+) pump current (arising from the 3:2 Na(+):K(+) exchange and normalized for membrane capacitance) as the shift in membrane current induced by 100 micromol/l ouabain. Ten nanomoles per liter ANP stimulated the Na(+)-K(+) pump when the intracellular compartment was perfused with pipette solutions containing 10 mmol/l Na(+) but had no effect when the pump was at near maximal activation with 80 mmol/l Na(+) in the pipette solution. Stimulation was abolished by inhibition of cGMP-activated protein kinase with KT-5823, nitric oxide (NO)-activated guanylyl cyclase with 1H-[1,2,4]oxadiazole[4,3-a]quinoxalin-1-one (ODQ), or NO synthase with N(G)-nitro-L-arginine methyl ester (L-NAME). Since synthesis of cGMP by NPR-A and NPR-B is not NO dependent or ODQ sensitive, we exposed myocytes to AP-811, a highly selective ligand for the NPR-C "clearance" receptor. It abolished ANP-induced pump stimulation. Conversely, the selective NPR-C agonist ANP(4-23) reproduced stimulation. The stimulation was blocked by l-NAME. To examine NO production in response to ANP(4-23), we loaded myocytes with the NO-sensitive fluorescent dye diacetylated diaminofluorescein-2 and examined them by confocal microscopy. ANP(4-23) induced a significant increase in fluorescence, which was abolished by L-NAME. We conclude that NPs stimulate the Na(+)-K(+) pump via an NPR-C and NO-dependent pathway. 相似文献
892.
LRWD1 Regulates Microtubule Nucleation and Proper Cell Cycle Progression in the Human Testicular Embryonic Carcinoma Cells 下载免费PDF全文
Chia‐Yih Wang Yu‐Han Hong Jhih‐Siang Syu Yung‐Chieh Tsai Xiu‐Ying Liu Ting‐Yu Chen Yin‐Mei Su Pao‐Lin Kuo Yung‐Ming Lin Yen‐Ni Teng 《Journal of cellular biochemistry》2018,119(1):314-326
Leucine‐rich repeats and WD repeat domain containing protein 1 (LRWD1) is a testis‐specific protein that mainly expressed in the sperm neck where centrosome is located. By using microarray analysis, LRWD1 is identified as a putative gene that involved in spermatogenesis. However, its role in human male germ cell development has not been extensively studied. When checking in the semen of patients with asthenozoospermia, teratozoospermia, and asthenoteratozoospermia, the level of LRWD1 in the sperm neck was significantly reduced with a defective neck or tail. When checking the sub‐cellular localization of LRWD1 in the cells, we found that LRWD1 resided in the centrosome and its centrosomal residency was independent of microtubule transportation in NT2/D1, the human testicular embryonic carcinoma, cell line. Depletion of LRWD1 did not induce centrosome re‐duplication but inhibited microtubule nucleation. In addition, the G1 arrest were observed in LRWD1 deficient NT2/D1 cells. Upon LRWD1 depletion, the levels of cyclin E, A, and phosphorylated CDK2, were reduced. Overexpression of LRWD1 promoted cell proliferation in NT2/D1, HeLa, and 239T cell lines. In addition, we also observed that autophagy was activated in LRWD1 deficient cells and inhibition of autophagy by chloroquine or bafilomycin A1 promoted cell death when LRWD1 was depleted. Thus, we found a novel function of LRWD1 in controlling microtubule nucleation and cell cycle progression in the human testicular embryonic carcinoma cells. J. Cell. Biochem. 119: 314–326, 2018. © 2017 Wiley Periodicals, Inc. 相似文献
893.
Inside Front Cover: Near‐infrared bone densitometry: A feasibility study on distal radius measurement (J. Biophotonics 7/2018) 下载免费PDF全文
This study provides a simple method to detect human distal radius bone density based on near infrared (NIR) imaging. The information of bone mineral density can be measured by transluminational optical bone densitometric system. Compared to dual‐energy x‐ray absorptiometry (DXA) results in clinical trial, NIR images show a strong correlation to DXA. Further details can be found in the article by Chun Chung, Yu‐Pin Chen, Tsai‐Hsueh Leu, and Chia‐Wei Sun ( e201700342 ).
894.
895.
Primate infants are born in an altricial state and rely on the care of their parents for a relatively long period of time.
Parental investment is critical to offspring survival and thus to the reproductive success of the parent as well. However,
mothers and infants may experience a conflict of interest, in that infants may benefit by receiving prolonged maternal care
but mothers may curtail such care in a tradeoff between investment in current versus future offspring. Documenting life history
characteristics, such as age at weaning, is important not only for understanding the conflicts of interest and tradeoffs;
such information can also provide insights about female reproductive rates and be valuable for conservation efforts. Little
is known about the life history of white-headed langurs (Trachypithecus leucocephalus), despite their endangered status. We were the first to investigate mother-infant relationships and infant behavioral development
in the species. We studied 3 wild mother-infant pairs throughout infancy. We used data from >460 h of focal subject sampling
to calculate the proportion of time individuals spent in different behavioral states and the frequency of instantaneous events,
such as maternal rejection. White-headed langur infants depended on their mothers for 19–21 mo, at which time they were weaned.
Maternal rejection facilitated infant independence in the early stages of infant development, and mothers stopped investing
in their infants when they resumed estrus. The weaning age of the wild white-headed langurs we studied was dramatically longer
than that of captives, possibly as a result of the nutritional differences between wild and captive populations. Weaning age
was also longer than for most other Asian colobines, and may be attributable to the degradation and fragmentation of their
natural habitat. 相似文献
896.
897.
Huanping Zhou Tze‐Bin Song Choong‐Heui Chung Bao Lei Brion Bob Rui Zhu Hsin‐Sheng Duan Chia‐Jung Hsu Yang Yang 《Liver Transplantation》2012,2(11):1368-1374
As a wide‐bandgap semiconductor, titanium dioxide (TiO2) with a porous structure has proven useful in dye‐sensitized solar cells, but its application in low‐cost, high‐efficiency inorganic photovoltaic devices based on materials such as Cu(InGa)Se2 or Cu2ZnSnS4 is limited. Here, a thin film made from solution‐processed TiO2 nanocrystals is demonstrated as an alternative to intrinsic zinc oxide (i‐ZnO) as the window layer of CuInSxSe1?x solar cells. The as‐synthesized, well‐dispersed, 6 nm TiO2 nanocrystals are assembled into thin films with controllable thicknesses of 40, 80, and 160 nm. The TiO2 nanocrystal films with thicknesses of 40 and 80 nm exhibit conversion efficiencies (6.2% and 6.33%, respectively) that are comparable to that of a layer of the typical sputtered i‐ZnO (6.42%). The conversion efficiency of the devices with a TiO2 thickness of 160 nm decreases to 2.2%, owing to the large series resistance. A 9‐hour reaction time leads to aggregated nanoparticles with a much‐lower efficiency (2%) than that of the well‐dispersed TiO2 nanoparticles prepared using a 15‐hour reaction time. Under optimized conditions, the champion TiO2 nanocrystal‐film‐based device shows even higher efficiency (9.2%) than a control device employing a typical i‐ZnO film (8.6%). 相似文献
898.
The fusion of myoblasts leading to the formation of myotubes is an integral part of skeletal myogenesis in many organisms. In Drosophila, specialized founder myoblasts initiate fusion through expression of the receptor-like attractant Dumbfounded (Duf), which brings them into close contact with other myoblasts. Here, we identify Rols7, a gene expressed in founders, as an essential component for fusion during myotube formation. During fusion, Rols7 localizes in a Duf-dependent manner at membrane sites that contact other myoblasts. These sites are also enriched with D-Titin, which functions to maintain myotube structure and morphology. When Rols7 is absent or its localization is perturbed, the enrichment of D-Titin fails to occur. Rols7 integrates the initial event of myoblast attraction with the downstream event of myotube structural organization by linking Duf to D-Titin. 相似文献
899.
Poh‐Kheng Ng Yu‐Shan Chiou Li‐Chia Liu Zhongmin Sun Hiromori Shimabukuro Showe‐Mei Lin 《Journal of phycology》2019,55(1):7-24
The evolutionary influences of historical and contemporary factors on the population connectivity and phylogeographic structure of a brown seaweed, Sargassum ilicifolium, were elucidated using the nuclear ITS2 and mitochondrial COI markers for the collections newly sampled within its distribution range in the northwestern Pacific (NWP). Significant genetic structure at variable levels was identified between populations (pairwise FST) and among populations grouped by geographical proximity (ΦCT among regions). The adjacent groups of populations with moderate structure revealed from AMOVA appeared to have high genetic connectivity. However, a lack of genealogical concordance with the geographic distribution was uncovered for S. ilicifolium from the NWP. Such genetic homogeneity is interpreted as a result of the interaction between postglacial recolonization and dynamic oceanic current regimes in the region. Two separated glacial refugia, the South China Sea and the Okinawa Trough, in the marginal seas of east China were recognized based on the presence of endemic haplotypes and high haplotype diversity in the populations at southern China and northeast of Taiwan. Populations persisting in these refugia may have served as the source for recolonization in the NWP with the rise of sea level during the warmer interglacial periods. The role of oceanic currents in maintaining genetic connectivity of S. ilicifolium in the region was further corroborated by the coherence between the direction of oceanic currents and that of gene flow, especially along the eastern coast of Taiwan. This study underlines the interaction between historical postglacial recolonization and contemporary coastal hydrodynamics in contributing to population connectivity and distribution for this tropical seaweed in the NWP. 相似文献
900.
Crystal structure of a conserved domain in the intermembrane space region of the plastid division protein ARC6 下载免费PDF全文
Nitin Kumar Abhijith Radhakrishnan Chih‐Chia Su Katherine W. Osteryoung Edward W. Yu 《Protein science : a publication of the Protein Society》2016,25(2):523-529
The chloroplast division machinery is composed of numerous proteins that assemble as a large complex to divide double‐membraned chloroplasts through binary fission. A key mediator of division‐complex formation is ARC6, a chloroplast inner envelope protein and evolutionary descendant of the cyanobacterial cell division protein Ftn2. ARC6 connects stromal and cytosolic contractile rings across the two membranes through interaction with an outer envelope protein within the intermembrane space (IMS). The ARC6 IMS region bears a structurally uncharacterized domain of unknown function, DUF4101, that is highly conserved among ARC6 and Ftn2 proteins. Here we report the crystal structure of this domain from Arabidopsis thaliana ARC6. The domain forms an α/β barrel open towards the outer envelope membrane but closed towards the inner envelope membrane. These findings provide new clues into how ARC6 and its homologs contribute to chloroplast and cyanobacterial cell division. 相似文献