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51.
Víctor M. Hernández-Rocamora Concepción García-Monta?és Belén Reija Bego?a Monterroso William Margolin Carlos Alfonso Silvia Zorrilla Germán Rivas 《The Journal of biological chemistry》2013,288(34):24625-24635
The interaction of MinC with FtsZ and its effects on FtsZ polymerization were studied under close to physiological conditions by a combination of biophysical methods. The Min system is a widely conserved mechanism in bacteria that ensures the correct placement of the division machinery at midcell. MinC is the component of this system that effectively interacts with FtsZ and inhibits the formation of the Z-ring. Here we report that MinC produces a concentration-dependent reduction in the size of GTP-induced FtsZ protofilaments (FtsZ-GTP) as demonstrated by analytical ultracentrifugation, dynamic light scattering, fluorescence correlation spectroscopy, and electron microscopy. Our experiments show that, despite being shorter, FtsZ protofilaments maintain their narrow distribution in size in the presence of MinC. The protein had the same effect regardless of its addition prior to or after FtsZ polymerization. Fluorescence anisotropy measurements indicated that MinC bound to FtsZ-GDP with a moderate affinity (apparent KD ∼10 μm at 100 mm KCl and pH 7.5) very close to the MinC concentration corresponding to the midpoint of the inhibition of FtsZ assembly. Only marginal binding of MinC to FtsZ-GTP protofilaments was observed by analytical ultracentrifugation and fluorescence correlation spectroscopy. Remarkably, MinC effects on FtsZ-GTP protofilaments and binding affinity to FtsZ-GDP were strongly dependent on ionic strength, being severely reduced at 500 mm KCl compared with 100 mm KCl. Our results support a mechanism in which MinC interacts with FtsZ-GDP, resulting in smaller protofilaments of defined size and having the same effect on both preassembled and growing FtsZ protofilaments. 相似文献
52.
Kathrin Schüller Dominik Bühler Nikolaus Plesnila 《Journal of visualized experiments : JoVE》2013,(81)
In this video publication a standardized mouse model of subarachnoid hemorrhage (SAH) is presented. Bleeding is induced by endovascular Circle of Willis perforation (CWp) and proven by intracranial pressure (ICP) monitoring. Thereby a homogenous blood distribution in subarachnoid spaces surrounding the arterial circulation and cerebellar fissures is achieved. Animal physiology is maintained by intubation, mechanical ventilation, and continuous on-line monitoring of various physiological and cardiovascular parameters: body temperature, systemic blood pressure, heart rate, and hemoglobin saturation. Thereby the cerebral perfusion pressure can be tightly monitored resulting in a less variable volume of extravasated blood. This allows a better standardization of endovascular filament perforation in mice and makes the whole model highly reproducible. Thus it is readily available for pharmacological and pathophysiological studies in wild type and genetically altered mice. 相似文献
53.
外源性视黄酸对斑马鱼心血管系统发育的影响 总被引:2,自引:0,他引:2
目的观察不同浓度外源性视黄酸对斑马鱼早期胚胎和心血管系统发育的影响,为进一步研究视黄酸影响斑马鱼心脏前后轴(A-P轴)发育的分子机制提供形态学依据。方法选择斑马鱼胚胎孵育的3,6,9·5,12h四个时间点,用不同浓度视黄酸(1×10-6,1×10-7,4×10-8,1×10-8mol/L)处理斑马鱼胚胎,在解剖显微镜下实时观察斑马鱼胚胎心脏发育的全过程和视黄酸对斑马鱼心脏发育的影响。并采用胚胎整体原位杂交技术观察flk-1mRNA在斑马鱼胚胎的表达。结果1×10-6mol/L视黄酸可导致斑马鱼胚胎表现出多系统的严重畸形,胚胎很快死亡。在胚胎孵育的9·5、12h给与10-7~10-8mol/L浓度的视黄酸,胚胎只表现出心血管系统的畸形,其他系统无明显异常。胚胎整体原位杂交显示视黄酸对flk-1mRNA在斑马鱼胚胎血管的表达没有影响。结论视黄酸影响斑马鱼胚胎心脏发育有剂量依赖性和严格的时间窗,视黄酸影响心脏前后轴发育的关键时间是原肠胚晚期。视黄酸处理组胚胎的循环缺陷主要为心脏发育异常所致。10-7~10-8mol/L浓度视黄酸在9·5、12h处理斑马鱼胚胎可以作为研究心脏发育调控机制的动物模型。 相似文献
54.
Recent advances in technologies such as DNA microarrays have provided an abundance of gene expression data on the genomic scale. One of the most important projects in the post-genome-era is the systemic identification of gene expression networks. However, inferring internal gene expression structure from experimentally observed time-series data are an inverse problem. We have therefore developed a system for inferring network candidates based on experimental observations. Moreover, we have proposed an analytical method for extracting common core binomial genetic interactions from various network candidates. Common core binomial genetic interactions are reliable interactions with a higher possibility of existence, and are important for understanding the dynamic behavior of gene expression networks. Here, we discuss an efficient method for inferring genetic interactions that combines a Step-by-step strategy (Y. Maki, Y. Takahashi, Y. Arikawa, S. Watanabe, K. Aoshima, Y. Eguchi, T. Ueda, S. Aburatani, S. Kuhara, M. Okamoto, An integrated comprehensive workbench for inferring genetic networks: Voyagene, Journal of Bioinformatics and Computational Biology 2(3) (2004) 533.) with an analysis method for extracting common core binomial genetic interactions. 相似文献
55.
The accumulation and seasonal impact of riverine discharge on coral reefs of the Meso-American Region (MAR) were estimated
using a numerical simulation of river runoff dispersion. River-reef connectivity, or source-sink dynamics of terrestrial runoff
was further assessed from more than 400 watersheds of the region onto discrete coral reef areas. Using land use for 2003 and
2004 in the MAR, this work builds upon a Regional Ocean Modeling System simulation of the MAR validated by ocean color satellite
data, and on the monthly river nutrient and sediment load and discharge provided by the World Resources Institute using the
N-SPECT model. Analysis of the variability of simulated runoff transport to the reefs showed that reefs of the Mesoamerican
Barrier Reef System (MBRS) were mostly impacted from June to September, following the peak time of river discharge. At that
time, the coastal and oceanic circulations contribute quickly to expel the runoff from the MBRS. High runoff concentration
waters leaving the eastern coast of Honduras during the months of October to December return to the southwestern MAR in March
as they are entrained in a cyclonic gyre. Coral reefs of the MAR are thus impacted twice, first from the coastal side with
runoff of local origin and later from the oceanic side with runoff from mixed origin. High probability of connectivity between
rivers and remote reefs is established as this study revealed that river runoff from the north shore of Honduras has a wide-spread
impact on most of the coral reefs of southern Belize, while watersheds on the Gulf of Honduras are mostly connected to coral
reefs in the northern shore of Honduras. Although the level of remote influence (or runoff concentration reaching the reef)
is lower than the local, the cumulative effect of numerous remote river-reef connections remains significant.
Communicated by Biology Editor Michael Lesser 相似文献
56.
诱发电位(EP)是继脑电图和肌电图之后临床神经电生理的第三大进展,在检测神经系统的状态和变化上有重要意义,常常用来协助确定神经系统的可疑病变,检出亚临床病灶,帮助病损定位,监护感觉系统的功能状态。其中,视觉、听觉和部分体感诱发电位已得到广泛应用。本文介绍了外阴诱发电位的相关原理及其应用等。 相似文献
57.
Hyung J. Kim Mi-Young Jeong Un Na Dennis R. Winge 《The Journal of biological chemistry》2012,287(48):40670-40679
The enzymatic function of succinate dehydrogenase (SDH) is dependent on covalent attachment of FAD on the ∼70-kDa flavoprotein subunit Sdh1. We show presently that flavinylation of the Sdh1 subunit of succinate dehydrogenase is dependent on a set of two spatially close C-terminal arginine residues that are distant from the FAD binding site. Mutation of Arg582 in yeast Sdh1 precludes flavinylation as well as assembly of the tetrameric enzyme complex. Mutation of Arg638 compromises SDH function only when present in combination with a Cys630 substitution. Mutations of either Arg582 or Arg638/Cys630 do not markedly destabilize the Sdh1 polypeptide; however, the steady-state level of Sdh5 is markedly attenuated in the Sdh1 mutant cells. With each mutant Sdh1, second-site Sdh1 suppressor mutations were recovered in Sdh1 permitting flavinylation, stabilization of Sdh5 and SDH tetramer assembly. SDH assembly appears to require FAD binding but not necessarily covalent FAD attachment. The Arg residues may be important not only for Sdh5 association but also in the recruitment and/or guidance of FAD and or succinate to the substrate site for the flavinylation reaction. The impaired assembly of SDH with the C-terminal Sdh1 mutants suggests that FAD binding is important to stabilize the Sdh1 conformation enabling association with Sdh2 and the membrane anchor subunits. 相似文献
58.
59.
Rogov VV Rogova NY Bernhard F Löhr F Dötsch V 《The Journal of biological chemistry》2011,286(21):18775-18783
RcsF, a proposed auxiliary regulator of the regulation of capsule synthesis (rcs) phosphorelay system, is a key element for understanding the RcsC-D-A/B signaling cascade, which is responsible for the regulation of more than 100 genes and is involved in cell division, motility, biofilm formation, and virulence. The RcsC-D-A/B system is one of the most complex bacterial signal transduction pathways, consisting of several membrane-bound and soluble proteins. RcsF is a lipoprotein attached to the outer membrane and plays an important role in activating the RcsC-d-A/B pathway. The exact mechanism of activation of the rcs phosphorelay by RcsF, however, remains unknown. We have analyzed the sequence of RcsF and identified three structural elements: 1) an N-terminal membrane-anchored helix (residues 3-13), 2) a loop (residues 14-48), and 3) a C-terminal folded domain (residues 49-134). We have determined the structure of this C-terminal domain and started to investigate its interaction with potential partners. Important features of its structure are two disulfide bridges between Cys-74 and Cys-118 and between Cys-109 and Cys-124. To evaluate the importance of this RcsF disulfide bridge network in vivo, we have examined the ability of the full-length protein and of specific Cys mutants to initiate the rcs signaling cascade. The results indicate that the Cys-74/Cys-118 and the Cys-109/Cys-124 residues correlate pairwise with the activity of RcsF. Interaction studies showed a weak interaction with an RNA hairpin. However, no interaction could be detected with reagents that are believed to activate the rcs phosphorelay, such as lysozyme, glucose, or Zn(2+) ions. 相似文献
60.