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91.
Prolonged in vivo functional assessment of the mouse oviduct using optical coherence tomography through a dorsal imaging window 下载免费PDF全文
The oviduct (or fallopian tube) serves as an environment for gamete transport, fertilization and preimplantation embryo development in mammals. Although there has been increasing evidence linking infertility with disrupted oviduct function, the specific roles that the oviduct plays in both normal and impaired reproductive processes remain unclear. The mouse is an important mammalian model to study human reproduction. However, most of the current analyses of the mouse oviduct rely on static histology or 2D visualization, and are unable to provide dynamic and volumetric characterization of this organ. The lack of imaging access prevents longitudinal live analysis of the oviduct and its associated reproductive events, limiting the understanding of mechanistic aspects of fertilization and preimplantation pregnancy. To address this limitation, we report a 3D imaging approach that enables prolonged functional assessment of the mouse oviduct in vivo. By combining optical coherence tomography with a dorsal imaging window, this method allows for extended volumetric visualization of the oviduct dynamics, which was previously not achievable. The approach is used for quantitative analysis of oviduct contraction, spatiotemporal characterization of cilia beat frequency and longitudinal imaging. This new approach is a useful in vivo imaging platform for a variety of live studies in mammalian reproduction. 相似文献
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The rate of vegetation recovery from boreal wildfire influences terrestrial carbon cycle processes and climate feedbacks by affecting the surface energy budget and land‐atmosphere carbon exchange. Previous forest recovery assessments using satellite optical‐infrared normalized difference vegetation index (NDVI) and tower CO2 eddy covariance techniques indicate rapid vegetation recovery within 5–10 years, but these techniques are not directly sensitive to changes in vegetation biomass. Alternatively, the vegetation optical depth (VOD) parameter from satellite passive microwave remote sensing can detect changes in canopy biomass structure and may provide a useful metric of post‐fire vegetation response to inform regional recovery assessments. We analyzed a multi‐year (2003–2010) satellite VOD record from the NASA AMSR‐E (Advanced Microwave Scanning Radiometer for EOS) sensor to estimate forest recovery trajectories for 14 large boreal fires from 2004 in Alaska and Canada. The VOD record indicated initial post‐fire canopy biomass recovery within 3–7 years, lagging NDVI recovery by 1–5 years. The VOD lag was attributed to slower non‐photosynthetic (woody) and photosynthetic (foliar) canopy biomass recovery, relative to the faster canopy greenness response indicated from the NDVI. The duration of VOD recovery to pre‐burn conditions was also directly proportional (P < 0.01) to satellite (moderate resolution imaging spectroradiometer) estimated tree cover loss used as a metric of fire severity. Our results indicate that vegetation biomass recovery from boreal fire disturbance is generally slower than reported from previous assessments based solely on satellite optical‐infrared remote sensing, while the VOD parameter enables more comprehensive assessments of boreal forest recovery. 相似文献
95.
The structural conversion of the prion protein PrP into a transmissible, misfolded form is the central element of prion disease, yet there is little consensus as to how it occurs. Key aspects of conversion into the diseased state remain unsettled, from details about the earliest stages of misfolding such as the involvement of partially- or fully-unfolded intermediates to the structure of the infectious state. Part of the difficulty in understanding the structural conversion arises from the complexity of the underlying energy landscapes. Single molecule methods provide a powerful tool for probing complex folding pathways as in prion misfolding, because they allow rare and transient events to be observed directly. We discuss recent work applying single-molecule probes to study misfolding in prion proteins, and what it has revealed about the folding dynamics of PrP that may underlie its unique behavior. We also discuss single-molecule studies probing the interactions that stabilize non-native structures within aggregates, pointing the way to future work that may help identify the microscopic events triggering pathogenic conversion. Although single-molecule approaches to misfolding are relatively young, they have a promising future in prion science. 相似文献
96.
A model optical immunosensor was developed to quantify an antibody present in a sample by measuring the fluorescence of Cyanine-5 conjugated with the antibody, using a competitive and a sandwich immunoreaction configuration, with the antigen immobilised in controlled pore glass beads. At pH 2, 94% of the antigen-antibody complex was dissociated, allowing reutilisation. Photobleaching had no effect on the fluorescence. This model system was used to detect Brucella sp. infection and could quantify anti-Brucella sp. antibodies in ovine serum samples in the range from 0.005 to 0.11 mg ml(-1). 相似文献
97.
Yu. V. Mezentsev A. A. Molnar O. V. Gnedenko Yu. V. Krasotkina N. N. Sokolov A. S. Ivanov 《Biochemistry (Moscow) Supplemental Series B: Biomedical Chemistry》2007,1(1):58-67
Bacterial L-asparaginases catalyzing hydrolysis of L-asparagine to L-aspartate and ammonia, are used in medical practice for treatment of acute lymphoblastic leukemia. The long-term therapy with these preparations is accompanied by a number of side effects, which are attributed to glutaminase activity of L-asparaginase. Substrate specificity and activity of L-asparaginases are directly associated with the oligomerization process of this enzyme, which is active only as the tetramer because its active sites are located in the contact areas between monomers. The present work is devoted to homology modeling of spatial structure of L-asparaginase from Erwinia carotovora, the comparative molecular-graphic analysis of subunit interfaces, and the development of a new experimental approach for studies of enzyme oligomerization. L-Asparaginase was immobilized on a surface of CM5 optical chip of biosensor Biacore 3000, which is based on the surface plasmon resonance technology. The dissociation process of enzyme tetrameric complexes up to monomers and subsequent oligomerization process have been registered. 相似文献
98.
【背景】道路重金属污染问题日益严峻,寻找高效的微生物资源用于环境修复已迫在眉睫。【目的】从乌鲁木齐市道路林带土壤中筛选抗重金属菌株,并对其重金属去除能力进行探究。【方法】使用含5种重金属离子(铅、镉、锌、铜、镍)的4种培养基进行抗性菌株筛选,通过形态学特征和16S rRNA基因序列进行鉴定,采用电感耦合等离子体发射光谱仪(inductively coupled plasma optical emission spectrometer,ICP-OES)检测分离株对重金属离子的去除情况。【结果】4种分离培养基中,TSA是抗重金属菌株筛选的最适培养基,共筛选出16株抗重金属菌,其中4株抗Pb菌、4株抗Cd菌、4株抗Zn菌、3株抗Cu菌和1株抗Ni菌,其抗性分别高达3 000、800、600、300和400mg/L,16株菌中以芽孢杆菌属(Bacillus)数量最多。在初始浓度为700mg/L Pb2+下,菌株Pb6的去除率高达92.48%,菌株Pb11、Pb3和Pb9的去除率分别为27.70%、40.37%和58.88%;在200mg/L Cd2+... 相似文献
99.
D. Landowne 《The Journal of membrane biology》1985,88(2):173-185
Summary Measurements of the changes in birefringence associated with changes in membrane potential were made with internally perfused squid giant axons in low sodium solutions at 0–8°C. The time course of the birefringence changes share many properties of the gating (polarization) currents previously studied in this nerve. Both can be demonstrated as an asymmetry in the response to voltage pulses symmetrical about the resting potential which is not present about a hyperpolarized holding potential. Both have a rapid relaxation, which precedes the sodium permeability change. Both exhibit an initial delay or rising phase. Both are reversibly blocked by perfusion with 30mm colchicine; neither are altered by changes on sodium concentrations or 300nm tetrodotoxin. The birefringence response has a decrease in the amplitude of the rapid relaxation associated with the appearance of a slow relaxation. This is similar to the immobilization of fast gating charges which parallels sodium current inactivation.The amplitude of the birefringence and the gating current responses is consistent with a change in the alignment of several hundred peptide bonds per sodium channel. 相似文献
100.
城市景观空间构型与热岛效应关联性较强,研究高时空分辨率的城市不同下垫面地表温度变化,可以更加精细地掌握城市热环境的时空特征。光纤温度传感系统具有实时在线、测温精度高和不受电磁干扰等优点,具备实时、在线、连续开展城市地表温度在线监测的能力。在北京市通州某园区内,选择有太阳辐射的4个时段,对多种类型下垫面的地表温度进行了时间间隔为1 min、空间间隔为1 m的连续4 h、总长度为100 m的实时在线监测。通过对监测时间段内不同类型下垫面地表温度的变化分析,发现这种分布式光纤测温系统能够有效辨识小尺度下地表温度的时间变化性和空间变化性,能有效区分透水和不透水地面,并监测和评估沥青马路地表温度的升温速率以及遮荫效果对地表温度的降温作用。同时,这种监测模式获取的数据能够对地表温度空间序列开展自相关分析,进一步验证了地表温度空间序列在较小尺度上仍然具有自相关性,且距离越近,相关性越大。研究同时表明,光纤测温技术能直接地获取城市热环境的现场真实数据,可以有效应用于小尺度城市热环境的观测与研究。 相似文献