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31.
Sandrine Villechanoux Monique Garnier Frédéric Laigret Joël Renaudin Joseph-Marie Bové 《Current microbiology》1993,26(3):161-166
We have recently cloned three DNA fragments (In-2.6, In-1.0, and In-0.6) of the noncultured, bacterial-like organism (BLO) associated with citrus greening disease. Nucleotide sequence determination has shown that fragment In-2.6 is part of therplKAJL-rpoBC gene cluster, a well-known operon in eubacteria. The DNA fragment upstream of and partially overlapping with In-2.6 could be isolated and was shown to be thenusG gene. InEscherichia coli, nusG is also immediately upstream ofrplKAJL-rpoBC. Fragment In-1.0 carries the gene for a bacteriophage type DNA polymerase. Fragment In-0.6 could not be identified.When In-2.6 was used, at high stringency, as a probe to detect greening BLO strains in infected plants, hybridization was obtained with all Asian strains tested, but not with the African strain examined. At lower stringencies, In-2.6 was able to detect also the African strain. The implications of these reults in the taxonomical position of the greening BLO are discussed. 相似文献
32.
33.
Renée Dallaire Alain Labrecque Mireille Marcotte Éric Bauce & Johanne Delisle 《Entomologia Experimentalis et Applicata》2004,112(3):169-181
The sublethal effects of tebufenozide, an ecdysone agonist, on the reproductive biology of Choristoneura fumiferana (Clem) and of Choristoneura rosaceana (Harris) (Lepidoptera: Tortricidae), treated during the larval stage, were evaluated using two treatment methods: the force‐feeding method and the diet method. The percentage of mortality and the developmental time of survivors increased linearly with the concentration of tebufenozide used. This ecdysone analogue proved to be more toxic to C. fumiferana than to C. rosaceana. In C. rosaceana, the weight of males and females decreased proportionally with the dose ingested, but females were affected to a greater extent. This difference might be due to a greater consumption of the treated diet, or to a differential vulnerability to tebufenozide. Tebufenozide did not modify the pre‐copulatory activities associated with chemical communication in the females. However, the consumption of tebufenozide delayed ovarian maturation, causing a reduction in the fecundity of females. Treated males had smaller spermatophores and fewer eupyrene sperms in their bursa copulatrix and spermatheca, along with lower mating success. In C. fumiferana, tebufenozide delayed the females’ onset time of calling the first night after emergence, but did not affect the mean time spent calling or the production of the main component of the sex pheromone. The males showed significantly greater difficulty in executing oriented flight in a wind tunnel, although their mating success was not affected. We concluded that tebufenozide interferes with various aspects of the reproductive biology of males and females of C. fumiferana and C. rosaceana, including some pre‐copulatory behaviors associated with sex pheromone communication. 相似文献
34.
Effects of SO2, aqueous fluoride (NaF) and a solution of nitrogen compounds (NH4NO3) on the visible symptoms, pollutant accumulation and ultrastructure of Scots pine (Pinus sylvestris L.) and Norway spruce [Picea abies (L.) Karst.] seedlings were studied in an open-air experiment lasting for 3 consecutive years. Visible injury symptoms were
most pronounced in combination exposures and whenever F was applied. Visible symptoms correlated well with needle pollutant
concentrations. Exposure to NaF increased needle F contents particularly when F was applied with SO2 or NH4NO3. This suggests that a reduction in N or SO2 emissions, in F polluted areas, could improve the condition of conifers via decreased accumulation of phytotoxic F in the
needles. Norway spruce needles accumulated 2 – 10 times as much S and F as those of Scots pine. Microscopic observations showed
various changes in the needle mesophyll cell ultrastructure. In both species, exposure to SO2 increased significantly the amount of cytoplasmic vacuoles, suggesting detoxification of excess sulphate or low pH. F treatments
resulted in a significant enlargement of plastoglobuli in Scots pine and a darkening of plastoglobuli in Norway spruce. All
exposures enhanced the accumulation of lipid bodies. An increased portion of translucent plastoglobuli was most pronounced
in N treatments. Many of the ultrastructural changes and visible symptoms appeared only as number of years exposed increased,
indicating that long-term experiments are needed. Both visible symptoms and ultrastructural changes pointed to the more pronounced
sensitivity of Norway spruce compared to Scots pine. Ultrastructural results mostly supported earlier qualitative observations
of F, N and SO2 effects on needle mesophyll cell ultrastructure. However, no reduction of thylakoids in SO2 containing exposure or curling of thylakoids in F exposure could be detected in the present study.
Received: 5 December 1994 / Accepted: 28 April 1995 相似文献
35.
In vitro influence of zinc and magnesium on the deformability of red blood cells artificially hardened by heating 总被引:2,自引:0,他引:2
Collette Dupuy-Fons Jean-Frédéric Brun Claire Mallart Joseph Carvajal Michèle Fussellier Lucette Bardet André Orsetti 《Biological trace element research》1995,47(1-3):247-255
Trace elements have been shown to improve red blood cell (RBC) deformability: zinc in sickle cell disease and magnesium in
an in vitro model of chemically rigidified erythrocytes. In this study, we investigated the effect and the influence of incubation
time of zinc or magnesium on an in vitro model of rigidified RBCs by heating. Erythrocyte rigidity was determined by viscosimetry
at high shear rate by a falling ball viscosimeter MT 90.
In the first part of the study, six normal volunteers participated. Viscosimetry was performed on native blood before and
after heating the sample for 10 min at 50°C. Therefore, increasing concentrations of zinc gluconate (final concentration:
0.5–4 g/L) or isotonic NaCl as control medium were added to the sample. Heating induced a twofold increase in all indices
of RBC rigidity (p<0.05). At all these concentrations of zinc, a highly significant, dose-related fluidifying effect was observed (40–70%):
this effect was immediately obtained and did not change over 60 min. Even at the highest concentration, recovery was not complete.
In the second part of the study, we studied magnesium’s effects on blood. In a first protocol, whole blood was rigidified
by heating at 56°C for 10 min, and the correcting effect of 5 min of incubation at 37°C of RBCs in 150 mmol/L NaCl, MgSO4, magnesium acetate, and magnesium gluconate was investigated. In a second protocol, the same incubation with NaCl and magnesium
salts was made on blood that had not been previously heated. In a third protocol, the correcting effect of magnesium gluconate
on heated red blood cells was tested at four concentrations (75, 150, 225, and 300 mmol/L) over 1 h, for evaluating the effects
of both concentration and time. Erythrocyte rigidity by heating is corrected by the three salts employed in protocol 1 (compared
to sodium). In protocol 2, the deformability of normal (nonheated) red cells is not modified by magnesium. In protocol 3,
no marked modification over 1 h is observed. The correcting effect is not complete for 75 mmol/L Mg, but remains the same
at the three other concentrations.
This study shows that zinc and magnesium at supraphysiological concentration are able to reverse RBC’s rigidification induced
by heating, but that magnesium does not modify the flexibility of normal RBCs. This article suggests that zinc and magnesium
may be studied in vivo as potential pharmacologic tools for improving hemorheologic disturbances. 相似文献
36.
Jean-Frédéric Brun Rosine Guintrand-Hugret Colette Fons Joseph Carvajal Christine Fedou Michelle Fussellier Lucette Bardet André Orsetti 《Biological trace element research》1995,47(1-3):385-391
Zinc improves both insulin secretion and insulin sensitivity, and exerts insulin-like effects. We investigated its acute effects on the parameters of glucose assimilation determined with the minimal model technique from frequent sampling intravenous glucose tolerance test (FSIVGTT) in seven healthy volunteers. FSIVGTTs (0.5 g/kg of glucose, followed by 2 U insulin iv injection at 19 min) were performed after the subjects had taken 20 mg zinc gluconate twice (the evening before and 30 min before the beginning of the test) or placebo pills (simple blind randomized protocol). Glucose assimilation was analyzed by calculating Kg (slope of the exponential decrease in glycemia), glucose effectiveness Sg (i.e., ability of glucose itself to increase its own disposal independent of insulin response), and SI (insulin sensitivity, i.e. the effect of increases in insulinemia on glucose disposal). The two latter parameters were calculated by fitting the experimental data with the two equations of Bergman’s “minimal model”. Zinc increased Kg (p<0.05) and Sg (p<0.05), whereas SI and insulin first-phase secretion did not significantly increase. This study suggests that zinc improves glucose assimilation, as evidenced by the increase in Kg, and that this improvement results mainly from an increase in glucose effectiveness (insulin-like effect), rather than an action on insulin response or insulin sensitivity. 相似文献
37.
Kader Thiam Estelle Loing Frédéric Gilles Claudie Verwaerde Brigitte Quatannens Claude Auriault Hélène Gras-Masse 《Letters in Peptide Science》1997,4(4-6):397-402
Intracellular enzymes or receptors are interesting targets for thepharmacomodulation of cellular metabolism. We have previously shown thatmodification of relatively long peptides by a palmitoyl-lysine residue couldfacilitate their delivery into the cytoplasm of living cells. Severalpeptides containing pseudosubstrate sequences of protein kinase C (PKC) havebeen evaluated for their ability to modulate phosphorylation of modelsubstrate, neuronal morphology or tumor necrosis factor secretion. In thiswork we have evaluated the effect of palmitoyl-modified PKC-pseudosubstratepeptides on induction of apoptosis. We have established that these peptidesare able to induce apoptosis in different human cell types (primaryfibroblasts, T- and B-lymphocyte cell lines) as assessed by (terminal deoxynucleotidyl transferase dUTP nick-end labelling) and DNAfragmentation. In contrast, control peptides (non-lipidicPKC-pseudosubstrate peptides and irrelevant lipopeptides) had no or littleeffect on programmed cell death. This work highlights the pharmacologicalinterest of lipopeptides and argues in favor of the potential role of PKC(s)in the cell death machinery. 相似文献
38.
39.
Prof. Dr. Ichiro Ichihara Martin Kallio Lauri J. Pelliniemi 《Cell and tissue research》1978,192(3):381-390
Summary The ducts of the rat ventral prostate have been studied by light and electron microscopy for elucidation of their role in prostatic function. The epithelium of the main duct consists of simple columnar cells and polymorphic basal cells. The columnar cells show no indication of secretory activity. The basal cells contain bundles of filaments of 5–6 nm thickness and numerous pinocytotic vesicles. The ducts are surrounded by layers of circular smooth muscle cells interspersed with nerve axons. On ultrastructural grounds the ducts do not appear to secrete material into the seminal fluid, but apparently the muscular coat actively helps drain the gland during ejaculation. 相似文献
40.
Adult-dystrophic chicken muscle had 30% higher tRNA methylase activity and 42% higher tRNA methylating capacity than normal-adult chicken muscle. Eighty percent of the tRNA methylase activity of the dystrophic muscle resulted in the synthesis of N2-methylguanine, and 9% in the formation of N2,N2-dimethylguanine. From adult-normal muscle extracts, 33% of the tRNA methylase activity was due to the synthesis of N2-methylguanine, and 45% to the formation of N2,N2-dimethylguanine. Eight other methylated bases accounted for 5–15% of the enzyme activity in both tissues. Dialyzed and nondialyzed adult-normal muscle extracts had equivalent tRNA methylase activity. However, the dialyzed extracts synthesized 22% more N2-methylguanine and 18% less N2,N2-dimethylguanine than the nondialyzed extracts. Dialysis had no effect on the tRNA methylase activity or tRNA methylation pattern produced by adult-dystrophic muscle. 相似文献