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861.
Structural colors are generated by scattering of light by variations in tissue nanostructure. They are widespread among animals and have been studied most extensively in butterflies and moths (Lepidoptera), which exhibit the widest diversity of photonic nanostructures, resultant colors, and visual effects of any extant organism. The evolution of structural coloration in lepidopterans, however, is poorly understood. Existing hypotheses based on phylogenetic and/or structural data are controversial and do not incorporate data from fossils. Here we report the first example of structurally colored scales in fossil lepidopterans; specimens are from the 47-million-year-old Messel oil shale (Germany). The preserved colors are generated by a multilayer reflector comprised of a stack of perforated laminae in the scale lumen; differently colored scales differ in their ultrastructure. The original colors were altered during fossilization but are reconstructed based upon preserved ultrastructural detail. The dorsal surface of the forewings was a yellow-green color that probably served as a dual-purpose defensive signal, i.e. aposematic during feeding and cryptic at rest. This visual signal was enhanced by suppression of iridescence (change in hue with viewing angle) achieved via two separate optical mechanisms: extensive perforation, and concave distortion, of the multilayer reflector. The fossils provide the first evidence, to our knowledge, for the function of structural color in fossils and demonstrate the feasibility of reconstructing color in non-metallic lepidopteran fossils. Plastic scale developmental processes and complex optical mechanisms for interspecific signaling had clearly evolved in lepidopterans by the mid-Eocene. 相似文献
862.
Junjie Xiao Huaming Cao Dandan Liang Ying Liu Hong Zhang Hong Zhao Yi Liu Jun Li Biao Yan Luying Peng Zhaonian Zhou Yi‐Han Chen 《Journal of cellular and molecular medicine》2011,15(5):1166-1176
Microtubule integrity is important in cardio‐protection, and microtubule disruption has been implicated in the response to ischemia in cardiac myocytes. However, the effects of Taxol, a common microtubule stabilizer, are still unknown in ischemic ventricular arrhythmias. The arrhythmia model was established in isolated rat hearts by regional ischemia, and myocardial infarction model by ischemia/reperfusion. Microtubule structure was immunohistochemically measured. The potential mechanisms were studied by measuring reactive oxygen species (ROS), activities of oxidative enzymes, intracellular calcium concentration ([Ca2+]i) and Ca2+ transients by using fluorometric determination, spectrophotometric assays and Fura‐2‐AM and Fluo‐3‐AM, respectively. The expression and activity of sarcoplasmic reticulum Ca2+‐ATPase (SERCA2a) was also examined using real‐time polymerase chain reaction, Western blot and pyruvate/Nicotinamide adenine dinucleotide‐coupled reaction. Our data showed that Taxol (0.1, 0.3 and 1 μM) effectively reduced the number of ventricular premature beats and the incidence and duration of ventricular tachycardia. The infarct size was also significantly reduced by Taxol (1 μM). At the same time, Taxol preserved the microtubule structure, increased the activity of mitochondrial electron transport chain complexes I and III, reduced ROS levels, decreased the rise in [Ca2+]i and preserved the amplitude and decay times of Ca2+ transients during ischemia. In addition, SERCA2a activity was preserved by Taxol during ischemia. In summary, Taxol prevents ischemic ventricular arrhythmias likely through ameliorating abnormal calcium homeostasis and decreasing the level of ROS. This study presents evidence that Taxol may be a potential novel therapy for ischemic ventricular arrhythmias. 相似文献
863.
Li Y Zheng H Luo R Wu H Zhu H Li R Cao H Wu B Huang S Shao H Ma H Zhang F Feng S Zhang W Du H Tian G Li J Zhang X Li S Bolund L Kristiansen K de Smith AJ Blakemore AI Coin LJ Yang H Wang J Wang J 《Nature biotechnology》2011,29(8):723-730
Here we use whole-genome de novo assembly of second-generation sequencing reads to map structural variation (SV) in an Asian genome and an African genome. Our approach identifies small- and intermediate-size homozygous variants (1-50 kb) including insertions, deletions, inversions and their precise breakpoints, and in contrast to other methods, can resolve complex rearrangements. In total, we identified 277,243 SVs ranging in length from 1-23 kb. Validation using computational and experimental methods suggests that we achieve overall <6% false-positive rate and <10% false-negative rate in genomic regions that can be assembled, which outperforms other methods. Analysis of the SVs in the genomes of 106 individuals sequenced as part of the 1000 Genomes Project suggests that SVs account for a greater fraction of the diversity between individuals than do single-nucleotide polymorphisms (SNPs). These findings demonstrate that whole-genome de novo assembly is a feasible approach to deriving more comprehensive maps of genetic variation. 相似文献
864.
Ibutilide is a newer class-III antiarrhythmic agent approved for clinical use. We sought to investigate its electrophysiological
effects in canines and also the underlying mechanism of conversion of atrial flutter (AFL). For this purpose, 15 male mongrel
dogs were anesthetized, intubated with tracheal tube, and heart was exposed and connected to electrodes. Electrophysiologic
variables were measured with and without ibutilide (10-min infusion-dose: 0.10 mg/kg; 30-min later, maintaining dose: 0.01 mg/min)
which included heart rate, conduction of intra- and inter-atrium, conduction ratio of isthmus, and ERP. Ibutilide had a significant
inhibitory effect on sinus atrial node, peak response time was 20–30 min, and heart rate returned to the baseline after 2 h.
One canine had 5 s sinus pause, and the other had 2:1 atrioventricular conduction post-administration. Atrial, ventricular,
and pulmonary vein ERP was significantly prolonged (P < 0.05). No significant differences were observed regarding conduction of intra-atrium, inter-atrium, and isthmus. It was,
therefore, concluded that ibutilide had suppressive effect on sinus atrial and atrioventricular nodes. Ibutilide rapidly terminated
AFL due to the reentrant wave front’s inability to proceed as the refractory period was protracted and hence caused the whole
excitable gap of the reentrant circuit to be affected by refractoriness. 相似文献
865.
Choksi S Lin Y Pobezinskaya Y Chen L Park C Morgan M Li T Jitkaew S Cao X Kim YS Kim HS Levitt P Shih G Birre M Deng CX Liu ZG 《Molecular cell》2011,42(5):597-609
The regulation of apoptosis is critical for controlling tissue homeostasis and preventing tumor formation and growth. Reactive oxygen species (ROS) generation plays a key role in such regulation. Here, we describe a HIF-1 target, Vasn/ATIA (anti-TNFα-induced apoptosis), which protects cells against TNFα- and hypoxia-induced apoptosis. Through the generation of ATIA knockout mice, we show that ATIA protects cells from apoptosis through regulating the function of the mitochondrial antioxidant, thioredoxin-2, and ROS generation. ATIA is highly expressed in human glioblastoma, and ATIA knockdown in glioblastoma cells renders them sensitive to hypoxia-induced apoptosis. Therefore, ATIA is not only a HIF-1 target that regulates mitochondrial redox pathways but also a potentially diagnostic marker and therapeutic target in human glioblastoma. 相似文献
866.
867.
868.
Youshuang Zhu Haibo Zhang Mingle Cao Zhenzhen Wei Feng Huang Peiji Gao 《Biotechnology and Bioprocess Engineering》2011,16(5):1027-1035
Production of laccase using a submerged culture of Trametes versicolor sdu-4 was optimized using a central composite design of the Response Surface Methodology. Optimized conditions gave a laccase
yield of 4,213 U/L which was approximately three times of that in basal medium. The laccase was purified to homogeneity using
a three-step process. The overall yield of the purification was 58%, with a purification fold of 11.4 and a specific activity
of 1320.7 U/mg protein. The molecular mass of the laccase was 60 kDa. The optimum pH values of the enzyme were 2.2, 3.7, and
7 for the oxidations of ABTS, DMP, and syringaldazine, respectively. The enzyme had adaptability to a broad pH range and high
temperature and wsa stable at pH 3.0 ∼ 10.0. The half-life of this laccase at 70°C was 2.2 h. Methyl red, 2-bromophenol, and
4-bromophenol were oxidized by the purified laccase in the absence of mediators. Purified laccase was effective in the decolorization
of several dyes and was not inhibited by Cu2+, Mn2+, Zn2+, Na+, K+, Mg2+, Ba2+, and Ca2+ at 5 mM. These excellent characteristics made it a highly attractive candidate for industrial use. 相似文献
869.
Bo Zhou Dan Peng Jianzhong Lin Xingqun Huang Wusheng Peng Reqing He Ming Guo Dongying Tang Xiaoying Zhao Xuanming Liu 《Journal of Plant Biology》2011,54(1):23-32
Gibberellins (GAs) are endogenous hormones that play an important role in regulating plant stature by increasing cell division
and promoting seed germination. The GA2-oxidase gene from Arabidopsis thaliana (AtGA2ox8) was introduced into Brassica napus L. by Agrobacterium-mediated floral-dip transformation with the aim of decreasing the amount of bioactive GA and hence reduced the plant height.
As anticipated, the transgenic plant exhibited dwarf phenotype. Importantly, compared with the wild type, the transgenic plants
had delayed the seed germination, increased the chlorophyll content (28.7–36.3%) and photosynthesis capacity (14.3–18.7%)
in a single leaf. At the same time, the photosynthesis capacity of the whole plants was significantly enhanced (35.7–48.6%)
due to the extra leaves and branches. 相似文献
870.
Cao Y Evans SC Soans E Malki A Liu Y Liu Y Chen X 《Apoptosis : an international journal on programmed cell death》2011,16(9):902-913
p53 is essential for cell cycle arrest and apoptosis induction while insulin receptor (IR) signaling is important for cell
metabolism and proliferation and found upregulated in cancers. While IR has recently been found to be involved in apoptosis,
p53 induction or apoptosis mediated through IR signaling activation has never been documented. Here, we report that the IR
signaling pathway, particularly the IR-MEK pathway, mediates biological and biochemical changes in p53 and apoptosis in tumor
cells. Specifically, natural compound penta-O-galloyl-α-d-glucopyranose (α-PGG), a previously characterized IR signaling activator, induced apoptosis in RKO cells without significantly
affecting its normal counterpart FHC cells. α-PGG induced apoptosis in RKO cells through p53, Bax and caspase 3. Importantly,
α-PGG’s ability to elevate p53 was diminished by IR inhibitor and IR-siRNA, suggesting a non-conventional role of IR as being
involved in p53 induction. Further studies revealed that α-PGG activated MEK, a downstream signaling factor of IR. Blocking
MEK significantly suppressed α-PGG-induced p53 and Bax elevation. All these results suggested that α-PGG induced p53, Bax,
and apoptosis through the IR-MEK signaling pathway. The unique activity of α-PGG, a novel IR phosphorylation and apoptosis
inducer, may offer a new therapeutic strategy for eliciting apoptotic signal and inhibiting cancer growth. 相似文献