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81.
Felipe?A.?Cisternas Gladys?Tapia Miguel?Arredondo Denise?Cartier-Ugarte Pamela?Romanque Walter?D.?Sierralta María?T.?Vial Luis?A.?Videla Magdalena?ArayaEmail author 《Biometals》2005,18(5):541-551
Cu is an essential trace element capable of producing toxic effects in animals and man when ingested acutely or chronically
in excess. Although chronic Cu exposure is increasingly recognized as a public health issue, its early effects remain largely
unknown. We approached the significance of a moderate chronic Cu load in young rats to correlate early hepatic histopathological
changes with functional alterations of liver cells. For this purpose, supplementation with 1200 ppm of Cu in rat food for
16 weeks was chosen. In these conditions, Cu load elicited a significant decrease in growth curves. There were mild light
microscopy alterations in Cu-treated rats, although increasing intracellular Cu storage was correlated with longer Cu exposure
both by histological and biochemical measurements. Ultrastructural alterations included lysosomal inclusions as well as mitochondrial
and nuclear changes. Liver perfusion studies revealed higher rates of basal O2 consumption and colloidal carbon-induced O2 uptake in Cu-treated rats, with enhanced carbon-induced O2/carbon uptake ratios and NF-κB DNA binding activity. These changes were time-dependent and returned to control values after
12 or16 weeks. It is concluded that subchronic Cu loading in young rats induces early hepatic morphological changes, with
enhancement in Küpffer cell-dependent respiratory burst activity and NF-κB DNA binding, cellular responses that may prevent
or alleviate the hepatotoxicity of the metal. 相似文献
82.
Complementary expression of IGF-II and IGFBP-5 during anterior pituitary development 总被引:1,自引:0,他引:1
The specification of the five individual hormone-secreting cell types in the anterior pituitary requires a series of sequential cell fate decisions. We have immortalized cells at several stages along this pathway of pituitary differentiation. Here, we present analysis of differences in gene expression between an anterior pituitary precursor cell line, alphaT1-1, and an immature gonadotrope cell line, alphaT3-1, identified by using cDNA subtraction. Messenger RNA expression of members of the insulin-like growth factor signaling system, IGF-II and IGFBP-5, was found in the alphaT1-1 precursor cell line, but not in the more differentiated cell line, alphaT3-1. This inferred stage specificity was confirmed in the mouse embryo by using in situ hybridization on embryonic days e10.5 through e18.5. Expression of IGF-II and IGFBP-5 mRNAs was both temporally and spatially regulated during pituitary development. IGF-II was highly expressed in the epithelium surrounding Rathke's pouch at e10.5, while IGFBP-5 expression was restricted to the adjacent oral epithelium. At e11.5 (represented by alphaT1-1), IGF-II was expressed throughout the pouch, but was coexpressed with IGFBP-5 and alpha-subunit in the ventral portion of the pouch epithelium. On e12.5, the two mRNAs were expressed in opposing dorsoventral (IGF-II) and ventrodorsal (IGFBP-5) patterns, with IGF-II excluded from the rostral, alpha-subunit-expressing region. A decrease of both mRNAs was observed at e14.5 (equivalent to alphaT3-1), with IGF-II levels low and IGFBP-5 concentrated in the anterior pituitary rostral tip. These findings suggest that the timing of IGF-II expression and regulation of its accessibility by IGFBP-5 may play a role in anterior pituitary differentiation, survival, and/or proliferation. 相似文献
83.
James J. Gilroy Graham W. Prescott Johann S. Cardenas Pamela González del Pliego Castañeda Andrés Sánchez Luis E. Rojas‐Murcia Claudia A. Medina Uribe Torbjørn Haugaasen David P. Edwards 《Global Change Biology》2015,21(4):1531-1540
Oil palm agriculture is rapidly expanding in the Neotropics, at the expense of a range of natural and seminatural habitats. A key question is how this expansion should be managed to reduce negative impacts on biodiversity. Focusing on the Llanos of Colombia, a mixed grassland–forest system identified as a priority zone for future oil palm development, we survey communities of ants, dung beetles, birds and herpetofauna occurring in oil palm plantations and the other principal form of agriculture in the region – improved cattle pasture – together with those of surrounding natural forests. We show that oil palm plantations have similar or higher species richness across all four taxonomic groups than improved pasture. For dung beetles, species richness in oil palm was equal to that of forest, whereas the other three taxa had highest species richness in forests. Hierarchical modelling of species occupancy probabilities indicated that oil palm plantations supported a higher proportion of species characteristic of forests than did cattle pastures. Across the bird community, occupancy probabilities within oil palm were positively influenced by increasing forest cover in a surrounding 250 m radius, whereas surrounding forest cover did not strongly influence the occurrence of other taxonomic groups in oil palm. Overall, our results suggest that the conversion of existing improved pastures to oil palm has limited negative impacts on biodiversity. As such, existing cattle pastures of the Colombian Llanos could offer a key opportunity to meet governmental targets for oil palm development without incurring significant biodiversity costs. Our results also highlight the value of preserving remnant forests within these agricultural landscapes, protecting high biodiversity and exporting avian ‘spill‐over’ effects into oil palm plantations. 相似文献
84.
Yuhsi Matuq Pamela S. Adams Nozomu Nishi Hidetaro Yasumitsu John W. Crabb Robert J. Matusik Wallace L. McKeehan 《In vitro cellular & developmental biology. Plant》1989,25(6):581-584
Summary Rat prostate extracts contain an abundant 20–22 kilodalton heparin-binding protein with near identical chromatographic properties,
but only 0.2–1% of the mitogenic activity, of bovine brain heparin-binding growth factor-1 (acidic fibroblast growth factor).
Amino terminal amino acid sequence (met-met-thr-asp-lys-asn-leu-lys-lys-lys-ile-glu-gly-asn-trp-arg-thr-val-tyr-leu-ala-ala-ser-?-val-glu-lys-ile-asn-glu-gly-ser-pro)
and immunochemical analysis revealed that the protein is identical to the androgen-dependent protein “probasin”.
This work was supported in part by NCI grant CA37589 (W. L. M., J. W. C.) and the Medical Research Council of Canada (R. J.
M.). 相似文献
85.
Michel P. Rathbone Pamela J. Middlemiss John W. Gysbers Susan DeForge Penny Costello Rolando F. Del Maestro 《In vitro cellular & developmental biology. Animal》1992,28(7-8):529-536
Summary Presumptive astrocytes isolated from 10-day white Leghorn chick embryos, Factor VIII-positive human brain capillary endothelial
cells, meningeal fibroblasts from 10-day chick embryos, Swiss mouse 3T3 cells, and human astrocytoma cell lines, SKMG-1 and
U373, were rendered quiescent when placed in culture medium that contained 0 or 0.2% serum for 48 h; their proliferation was
markedly reduced and they incorporated [3H]thymidine at a low rate. [3H]Thymidine incorporation and cell proliferation were induced in all types of cells by addition of guanosine, GMP, GDP, GTP,
and to a lesser extent, adenosine, AMP, ADP or ATP to the culture medium. The stimulation of proliferation by adenosine and
guanosine was abolished by 1,3-dipropyl-7-methylxanthine (DPMX), an adenosine A2 receptor antagonist, but not by 1,3,-dipropyl-8-(2-amino-4-chorophenyl)xanthine (PACPX), an A1 antagonist. Stimulation of proliferation by the nucleotides was not abolished by either DPMX or PACPX. The P2 receptor agonists,α,β-methyleneATP and 2-methylthioATP, also stimulated [3H]thymidine incorporation into the cells with peak activity at approximately 3.5 and 0.03 nM, respectively. These data imply that adenosine and guanosine stimulate proliferation of these cell types through activation
of an adenosine A2 receptor, and the stimulation of cell proliferation by the nucleotides may be due to the activation of purinergic P2y receptors. As the primary cultures grew older their growth rate slowed. The capacity of the purine nucleosides and nucleotides
to stimulate their growth diminished concomitantly. The 3T3 cells showed neither decreased growth with increased passages
nor reduced response to the purines. In contrast, although the doubling time of the immortalized human astrocytoma cell lines
SKMG-1 and U373 remained constant, the responsiveness to purinergic stimulation of the U373 cells decreased but that of the
SKMG-1 did not. These data are compatible with a decrease in the number, or the ligand-binding affinity of the purinergic
receptors, or a decreased coupling of purinergic receptors to intracellular mediators in primary cells aged in tissue culture. 相似文献
86.
Belinda Martineau H. Jane Smith Caroline Dean Pamela Dunsmuir John Bedbrook Laurens J. Mets 《Plant molecular biology》1989,13(4):419-426
We report the successful transformation, via Agrobacterium tumefaciens infection, and regeneration of two species of the genus Flaveria: F. brownii and F. palmeri. We document the expression of a C3 plant gene, an abundantly expressed ribulose 1,5-bisphosphate carboxylase/oxygenase small subunit gene isolated from petunia, in these C4 plants. The organ-specific expression of this petunia gene in Flaveria brownii is qualitatively identical to its endogenous pattern of expression. 相似文献
87.
Gary Gibson Pamela Nielsen Victoria Mykytyn Ken Carlson John Blass 《Neurochemical research》1989,14(1):17-24
To further elucidate the molecular basis of the selective damage to various brain regions by thiamin deficiency, changes in enzymatic activities were compared to carbohydrate flux through various pathways from vulnerable (mammillary bodies and inferior colliculi) and nonvulnerable (cochlear nuclei) regions after 11 or 14 days of pyrithiamin-induced thiamin deficiency. After 11 days,large decreases (–43 to –59%) in transketolase (TK) occurred in all 3 regions; 2-ketoglutarate dehydrogenase (KGDHC) declined (–45%), but only in mammillary bodies; pyruvate dehydrogenase (PDHC) was unaffected. By day 14, TK remained reduced by 58%–66%; KGDHC was now reduced in all regions (–48 to –55%); PDHC was also reduced (–32%), but only in the mammillary bodies. Thus, the enzyme changes did not parallel the pathological vulnerability of these regions to thiamin deficiency.14CO2 production from14C-glucose labeled in various positions was utilized to assess metabolic flux. After 14 days, CO2 production in the vulnerable regions declined severely (–46 to 70%) and approximately twice as much as those in the cochlear nucleus. Also by day 14, the ratio of enzymatic activity to metabolic flux increased as much as 56% in the vulnerable regions, but decreased 18 to 30% in the cochlear nuclei. These differences reflect a greater decrease in flux than enzyme activities in the two vulnerable regions. Thus, selective cellular responses to thiamin deficiency can be demonstrated ex vivo, and these changes can be directly related to alterations in metabolic flux. Since they cannot be related to enzymatic alterations in the three regions, factors other than decreases in the activity of these TPP-dependent enzymes must underlie selective vulnerability in this model of thiamin deficiency.Abbreviations KGDHC
2-ketoglutarate dehydrogenase complex EC 1.2.4.2., EC 2.3.1.61, EC 1.6.4.3.
- PDHC
pyruvate dehydrogenase complex EC 1.2.4.2., EC 2.3.1.12, EC 1.6.4.3
- TK
transketolase (EC 2.2.1.1)
- TPP
thiamin pyrophosphate 相似文献
88.
Tatarkiewicz K Smith PA Sablan EJ Polizzi CJ Aumann DE Villescaz C Hargrove DM Gedulin BR Lu MG Adams L Whisenant T Roy D Parkes DG 《American journal of physiology. Endocrinology and metabolism》2010,299(6):E1076-E1086
The risk of developing pancreatitis is elevated in type 2 diabetes and obesity. Cases of pancreatitis have been reported in type 2 diabetes patients treated with GLP-1 (GLP-1R) receptor agonists. To examine whether the GLP-1R agonist exenatide potentially induces or modulates pancreatitis, the effect of exenatide was evaluated in normal or diabetic rodents. Normal and diabetic rats received a single exenatide dose (0.072, 0.24, and 0.72 nmol/kg) or vehicle. Diabetic ob/ob or HF-STZ mice were infused with exenatide (1.2 and 7.2 nmol·kg(-1)·day(-1)) or vehicle for 4 wk. Post-exenatide treatment, pancreatitis was induced with caerulein (CRN) or sodium taurocholate (ST), and changes in plasma amylase and lipase were measured. In ob/ob mice, plasma cytokines (IL-1β, IL-2, IL-6, MCP-1, IFNγ, and TNFα) and pancreatitis-associated genes were assessed. Pancreata were weighed and examined histologically. Exenatide treatment alone did not modify plasma amylase or lipase in any models tested. Exenatide attenuated CRN-induced release of amylase and lipase in normal rats and ob/ob mice but did not modify the response to ST infusion. Plasma cytokines and pancreatic weight were unaffected by exenatide. Exenatide upregulated Reg3b but not Il6, Ccl2, Nfkb1, or Vamp8 expression. Histological analysis revealed that the highest doses of exenatide decreased CRN- or ST-induced acute inflammation, vacuolation, and acinar single cell necrosis in mice and rats, respectively. Ductal cell proliferation rates were low and similar across all groups of ob/ob mice. In conclusion, exenatide did not modify plasma amylase and lipase concentrations in rodents without pancreatitis and improved chemically induced pancreatitis in normal and diabetic rodents. 相似文献
89.
90.