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991.
The Rooting of the Universal Tree of Life Is Not Reliable 总被引:19,自引:0,他引:19
Several composite universal trees connected by an ancestral gene duplication have been used to root the universal tree of
life. In all cases, this root turned out to be in the eubacterial branch. However, the validity of results obtained from comparative
sequence analysis has recently been questioned, in particular, in the case of ancient phylogenies. For example, it has been
shown that several eukaryotic groups are misplaced in ribosomal RNA or elongation factor trees because of unequal rates of
evolution and mutational saturation. Furthermore, the addition of new sequences to data sets has often turned apparently reasonable
phylogenies into confused ones. We have thus revisited all composite protein trees that have been used to root the universal
tree of life up to now (elongation factors, ATPases, tRNA synthetases, carbamoyl phosphate synthetases, signal recognition
particle proteins) with updated data sets. In general, the two prokaryotic domains were not monophyletic with several aberrant
groupings at different levels of the tree. Furthermore, the respective phylogenies contradicted each others, so that various
ad hoc scenarios (paralogy or lateral gene transfer) must be proposed in order to obtain the traditional Archaebacteria–Eukaryota
sisterhood. More importantly, all of the markers are heavily saturated with respect to amino acid substitutions. As phylogenies
inferred from saturated data sets are extremely sensitive to differences in evolutionary rates, present phylogenies used to
root the universal tree of life could be biased by the phenomenon of long branch attraction. Since the eubacterial branch
was always the longest one, the eubacterial rooting could be explained by an attraction between this branch and the long branch
of the outgroup. Finally, we suggested that an eukaryotic rooting could be a more fruitful working hypothesis, as it provides,
for example, a simple explanation to the high genetic similarity of Archaebacteria and Eubacteria inferred from complete genome
analysis. 相似文献
992.
993.
Goñi-Oliver P Lucas JJ Avila J Hernández F 《The Journal of biological chemistry》2007,282(31):22406-22413
Although GSK-3 activity can be regulated by phosphorylation and through interaction with GSK-3-binding proteins, here we describe N-terminal proteolysis as a novel way to regulate GSK-3. When brain extracts were exposed to calcium, GSK-3 was truncated, generating two fragments of approximately 40 and 30 kDa, a proteolytic process that was inhibited by specific calpain inhibitors. Interestingly, instead of inhibiting this enzyme, GSK-3 truncation augmented its kinase activity. When we digested recombinant GSK-3 alpha and GSK-3beta protein with calpain, each isoform was cleaved differently, yet the truncated GSK-3 isoforms were still active kinases. We also found that lithium, a GSK-3 inhibitor, inhibits full-length and cleaved GSK-3 isoforms with the same IC(50) value. Calpain removed the N-terminal ends of His-tagged GSK-3 isoenzymes, and exposing cultured cortical neurons with ionomycin, glutamate, or N-methyl-d-aspartate led to the truncation of GSK-3. This truncation was blocked by the calpain inhibitor calpeptin, at the same concentration at which it inhibits calpain-mediated cleavage of NMDAR-2B and of p35 (the regulatory subunit of CDK5). Together, our data demonstrate that calpain activation produces a truncation of GSK-3 that removes an N-terminal inhibitory domain. Furthermore, we show that GSK-3 alpha and GSK-3beta isoenzymes have a different susceptibility to this cleavage, suggesting a means to specifically regulate these isoenzymes. These data provide the first direct evidence that calpain promotes GSK-3 truncation in a way that has implications in signal transduction, and probably in pathological disorders such as Alzheimer disease. 相似文献
994.
González R Collado JA Nell S Briceño J Tamayo MJ Fraga E Bernardos A López-Cillero P Pascussi JM Rufián S Vilarem MJ De la Mata M Brigelius-Flohe R Maurel P Muntané J 《Free radical biology & medicine》2007,43(10):1439-1452
Vitamin E (alpha-tocopherol) has demonstrated antioxidant activity and gene-regulatory properties. d-Galactosamine (D-GalN)-induced cell death is mediated by nitric oxide in hepatocytes, and it is associated with hepatic steatosis. The beneficial properties of alpha-tocopherol and their relation to oxidative stress and gene regulation were assessed in D-GalN-induced cell death. Hepatocytes were isolated from human liver resections by a collagenase perfusion technique. alpha-Tocopherol (50 microM) was administered at the advanced stages (10 h) of D-GalN-induced cell death in cultured hepatocytes. Cell death, oxidative stress, alpha-tocopherol metabolism, and NF-kappaB-, pregnane X receptor (PXR)-, and peroxisome proliferator-activated receptor (PPAR-alpha)-associated gene regulation were estimated in the hepatocytes. D-GalN increased cell death and alpha-tocopherol metabolism. alpha-Tocopherol exerted a moderate beneficial effect against apoptosis and necrosis induced by D-GalN. Induction (rifampicin) or inhibition (ketoconazole) of alpha-tocopherol metabolism and overexpression of PXR showed that the increase in PXR-related CYP3A4 expression caused by alpha-tocopherol enhanced cell death in hepatocytes. Nevertheless, the reduction in NF-kappaB activation and inducible nitric oxide synthase expression and the enhancement of PPAR-alpha and carnitine palmitoyl transferase gene expression by alpha-tocopherol may be relevant for cell survival. In conclusion, the cytoprotective properties of alpha-tocopherol are mostly related to gene regulation rather than to antioxidant activity in toxin-induced cell death in hepatocytes. 相似文献
995.
Dendritic cells are less susceptible to human immunodeficiency virus type 2 (HIV-2) infection than to HIV-1 infection 总被引:1,自引:0,他引:1
Duvall MG Loré K Blaak H Ambrozak DA Adams WC Santos K Geldmacher C Mascola JR McMichael AJ Jaye A Whittle HC Rowland-Jones SL Koup RA 《Journal of virology》2007,81(24):13486-13498
Human immunodeficiency virus type 1 (HIV-1) infection of dendritic cells (DCs) has been documented in vivo and may be an important contributor to HIV-1 transmission and pathogenesis. HIV-1-specific CD4+ T cells respond to HIV antigens presented by HIV-1-infected DCs and in this process become infected, thereby providing a mechanism through which HIV-1-specific CD4+ T cells could become preferentially infected in vivo. HIV-2 disease is attenuated with respect to HIV-1 disease, and host immune responses are thought to be contributory. Here we investigated the susceptibility of primary myeloid DCs (mDCs) and plasmacytoid DCs (pDCs) to infection by HIV-2. We found that neither CCR5-tropic primary HIV-2 isolates nor a lab-adapted CXCR4-tropic HIV-2 strain could efficiently infect mDCs or pDCs, though these viruses could infect primary CD4+ T cells in vitro. HIV-2-exposed mDCs were also incapable of transferring virus to autologous CD4+ T cells. Despite this, we found that HIV-2-specific CD4+ T cells contained more viral DNA than memory CD4+ T cells of other specificities in vivo. These data suggest that either infection of DCs is not an important contributor to infection of HIV-2-specific CD4+ T cells in vivo or that infection of DCs by HIV-2 occurs at a level that is undetectable in vitro. The frequent carriage of HIV-2 DNA within HIV-2-specific CD4+ T cells, however, does not appear to be incompatible with preserved numbers and functionality of HIV-2-specific CD4+ T cells in vivo, suggesting that additional mechanisms contribute to maintenance of HIV-2-specific CD4+ T-cell help in vivo. 相似文献
996.
Ana Luiza Menegatti Pavan Maria Eugênia Dela Rosa Guilherme Giacomini Fernando Antonio Bacchim Neto Seizo Yamashita Luiz Carlos Vulcano Sergio Barbosa Duarte José Ricardo de Arruda Miranda Diana Rodrigues de Pina 《PloS one》2016,11(4)
Digital radiographic imaging is increasing in veterinary practice. The use of radiation demands responsibility to maintain high image quality. Low doses are necessary because workers are requested to restrain the animal. Optimizing digital systems is necessary to avoid unnecessary exposure, causing the phenomenon known as dose creep. Homogeneous phantoms are widely used to optimize image quality and dose. We developed an automatic computational methodology to classify and quantify tissues (i.e., lung tissue, adipose tissue, muscle tissue, and bone) in canine chest computed tomography exams. The thickness of each tissue was converted to simulator materials (i.e., Lucite, aluminum, and air). Dogs were separated into groups of 20 animals each according to weight. Mean weights were 6.5 ± 2.0 kg, 15.0 ± 5.0 kg, 32.0 ± 5.5 kg, and 50.0 ± 12.0 kg, for the small, medium, large, and giant groups, respectively. The one-way analysis of variance revealed significant differences in all simulator material thicknesses (p < 0.05) quantified between groups. As a result, four phantoms were constructed for dorsoventral and lateral views. In conclusion, the present methodology allows the development of phantoms of the canine chest and possibly other body regions and/or animals. The proposed phantom is a practical tool that may be employed in future work to optimize veterinary X-ray procedures. 相似文献
997.
José Angel Herrera‐Vásquez Deibis Ortega Ana Belkis Romero Salvatore Davino Luis Carlos Mejía Stefano Panno Mario Davino 《Journal of Phytopathology》2016,164(2):102-113
The key regions in Panama involved in open field‐ and greenhouse‐grown commercial tomato production, including the Chiriquí, Veraguas, Herrera, Los Santos, Coclé and Panama Oeste provinces, were surveyed for the incidence and distribution of begomoviruses in the growing seasons of 2011 and 2012. The surveys took place in 14 of the 51 districts of the above‐mentioned provinces and comprised all relevant tomato production areas of the provinces. A total of 28 tomato plots were surveyed. The exact location of each plot was geo‐referenced using a hand‐held Global Positioning System unit. In total, 319 individual tomato plants (181 in 2011 and 138 in 2012) were sampled. Plants displayed diverse combinations of virus‐like symptoms of different severity, including necrosis, yellowing, mosaic, mottling, rolling, curling, distortion and puckering of leaves, reduced leaf size, and stunted growth. DNA was extracted from each plant for a subsequent polymerase chain reaction (PCR) analysis, using two sets of degenerate primers able to detect members of the genus Begomovirus. The samples displaying a positive reaction were subsequently analysed with specific primer pairs to identify the affecting begomoviruses. A total of 42.3% of all collected samples showed a positive signal to PCRs. Three begomovirus species were detected with the species‐specific set of primers; in particular, in the samples obtained in 2011, Potato yellow mosaic Panama virus (PYMPV), Tomato leaf curl Sinaloa virus (ToLCSiV) and Tomato yellow mottle virus (TYMoV) were detected, while in the 2012 samples, only PYMPV and ToLCSiV were found. To our knowledge, this is the first reported incidence of ToLCSiV and TYMoV in Panamanian tomato crops. 相似文献
998.
Nasoethmoidal meningocele in a child presenting bilateral congenital cystic adenomatoid malformation: Evidence for a new entity or consequence of gestational exposures? 下载免费PDF全文
Ernani B. da Rosa Daniélle B. Silveira Laís G. Tsugami Nathan L. Bellé Izabelle O. Matos Luciano V. Targa Rosilene da S. Betat André C. da Cunha Rolando A.R. Villacis Sílvia R. Rogatto Luiza E. Dorfman Rafael F. M. Rosa Paulo R.G. Zen 《Birth defects research. Part A, Clinical and molecular teratology》2016,106(4):225-231
999.
1000.
Potential for oilseed rape resistance in pollen beetle control 总被引:1,自引:0,他引:1
Breeding for plant resistance to insect pests is a classic strategy in integrated management, but it has never been developed for use against European pests of oilseed rape (Brassica napus) (OSR), especially one of the most damaging ones, the pollen beetle (Meligethes aeneus). In this paper we look at the three strategies that could be employed to improve OSR resistance (based on transgenes, relatives of B. napus or OSR natural variation) and review our current knowledge as to how these strategies could be put into practice. We identify the drawbacks which are specific to the pollen beetle that could impede breeding programs for resistance, and propose an approach to circumvent them. Finally, we detail the steps of the interaction between OSR and the pollen beetle that could be targeted in order to improve plant resistance (host plant location, adult survival, adult feeding, egg production and oviposition, larval development) and discuss their efficiency and durability potential. 相似文献