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991.
A trypsin inhibitor was isolated from Cassia obtusifolia by ammonium sulfate precipitation, Sepharose 4B-trypsin affinity and Sephadex G-75 chromatography. The inhibitor consisted
of a single polypeptide chain with a molecular mass of 19, 812.55 Da. It was stable from pH 2 to 12 for 24 h, whereas it was
unstable either above 70°C for 10 min or under reduced conditions. The inhibitor, which inhibited trypsin activity with an
apparent Ki of 0.3 μM, had one reactive site involving a lysine residue. The native inhibitor was resistant to pepsin digestion, whereas
the heated inhibitor produced 40% degree of susceptibility. The disulfide linkage and lysine residue were important in maintaining
its conformation. Partial amino acid sequence of the purified protein showed a high degree of homology with various members
of the Kunitz inhibitor family. Moreover, the inhibitor showed significant inhibitory activity against trypsin-like proteases
present in the larval midgut on Pieris rapae and could suppress the growth of larvae. 相似文献
992.
This study first reports the absorption kinetics of GST-TatdMt, a recombinant Tat protein possessing potent anti-obesity activity, in rats after nasal, s.c., and p.o. administration. GST-TatdMt was over-expressed in E. coli, purified, and radioiodinated using the IODO-GEN method. The radioiodinated 125I-GST-TatdMt was administered to rats by nasal, s.c., and oral routes at doses of 7.3 microg (420.7 nCi), 146.5 microg (8413.8 nCi), and 146.5 microg (8413.8 nCi), respectively. For the determination of absolute bioavailability, 125I-GST-TatdMt was also given to rats by i.v. injection (73.2 microg, 4206.9 nCi). Following administration by extravascular routes, the systemic absorption of radioactivity was prolonged, with Cmax being attained within 4.2-8.0 h. The absolute bioavailability calculated as dose-normalized AUC(extravascular)/AUC(i.v.) was 98.0, 75.8, and 87.1% after nasal, s.c., and oral administration, respectively. The majority of administered radioactivity was excreted in urine (57.5-64.7%), with fecal excretion being less (2.5-12.7%). The distribution of 125I-GST-TatdMt to various tissues was also determined at 4 and 72 h after s.c. injection. The findings of this study suggest that this protein may be absorbed into the systemic circulation when given by extravascular administration. 相似文献
993.
We investigated the effects of ions and temperature on the binding of E. coli to heparin using a chemiluminescence electrophoretic mobility shift assay. We found that magnesium ion is an effective inhibitor of the binding. The method can be readily applied to discover agents that can block the binding. 相似文献
994.
Inflammation is known to be an important underlying condition in the development of a variety of diseases. To investigate whether blood lead induces inflammatory reactions in non-occupationally exposed adults and the effects of genetic susceptibility associated with GSTM1 and TNF-alpha gene polymorphisms on this inflammatory response, we measured blood lead levels in 300 healthy university students. Total serum TNF-alpha and IL-6 levels and WBC counts were determined to evaluate the inflammatory response. Allelic loss of GSTM1 and the TNF-alpha-308 G>A polymorphism were determined by PCR and RFLP. Positive relations between blood lead and three inflammation biomarkers were shown in male subjects with blood lead > or =2.51microg/dl (median value) (TNF-alpha, p=0.015; IL-6, p=0.082; and WBC, p=0.044). However, subgroup analysis by genotype showed an effect of blood lead on the three biomarkers only in individuals with the GSTM1 null (TNF-alpha, p=0.020; IL-6, p=0.096; and WBC, p=0.017) or TNF-alpha GG (TNF-alpha, p=0.017; IL-6, p=0.088; and WBC, p=0.095) genotype, and not in individuals with GSTM1 present (all three inflammatory biomarkers, p>0.1) or the TNF-alpha GA or AA (all three biomarkers, p>0.1) genotype. These results suggest that blood lead affects the inflammatory response and that GSTM1 and TNF-alpha gene polymorphisms are genetic factors associated with lead-induced inflammatory response. 相似文献
995.
Senthil-Kumar M Hema R Anand A Kang L Udayakumar M Mysore KS 《The New phytologist》2007,176(4):782-791
Virus-induced gene silencing (VIGS) is a rapid and robust method for determining and studying the function of plant genes or expressed sequence tags (ESTs). However, only a few plant species are amenable to VIGS. There is a need for a systematic study to identify VIGS-efficient plant species and to determine the extent of homology required between the heterologous genes and their endogenous orthologs for silencing. Two approaches were used. First, the extent of phytoene desaturase (PDS) gene silencing was studied in various Solanaceous plant species using Nicotiana benthamiana NbPDS sequences. In the second approach, PDS sequences from a wide range of plant species were used to silence the PDS gene in N. benthamiana. The results showed that tobacco rattle virus (TRV)-mediated VIGS can be performed in a wide range of Solanaceous plant species and that heterologous gene sequences from far-related plant species can be used to silence their respective orthologs in the VIGS-efficient plant N. benthamiana. A correlation was not always found between gene silencing efficiency and percentage homology of the heterologous gene sequence with the endogenous gene sequence. It was concluded that a 21-nucleotide stretch of 100% identity between the heterologous and endogenous gene sequences is not absolutely required for gene silencing. 相似文献
996.
In this study, via a bioactivity-guided fractionation of MeOH extracts of the fruits of Piper nigrum, alkamide (5) and five previously-identified alkamides were isolated. Their structures were elucidated via spectroscopic analysis ((1)H, (13)C NMR and ESI-MS), as follows: retrofractamide A (1), pipercide (2), piperchabamide D (3), pellitorin (4), dehydroretrofractamide C (5) and dehydropipernonaline (6). The IC(50) values determined for the compounds were 24.5 (1), 3.7 (2), 13.5 (3), 40.5 (4), 60 (5) and 90 microM (6), according to the results of an ACAT enzyme assay system using rat liver microsomes. These compounds all inhibited cholesterol esterification in HepG2 cells. 相似文献
997.
998.
Comparison of APRI and Hydrus-2D models to simulate soil water dynamics in a vineyard under alternate partial root zone drip irrigation 总被引:2,自引:0,他引:2
Alternate partial root zone irrigation (APRI) is a new water-saving irrigation technique. It can reduce irrigation water and
transpiration without reduction in crop yield, thus increase water and nutrient use efficiency. Understanding of soil moisture
distribution and dynamic under the alternate partial root zone drip irrigation (APDI) can help to develop the efficient irrigation
schemes. In this paper, a two-dimensional (2D) root water uptake model was proposed based on soil water dynamic and root distribution
of grape vine, and a function of soil evaporation related to soil water content was defined under the APDI. Then the soil
water dynamic model of APDI (APRI-model) was developed based on the 2D root water uptake model and soil evaporation function
combined with average measured soil moisture content at 0–10 cm soil layer. Soil water dynamic in APDI was respectively simulated
by Hydrus-2D model and APRI-model. The simulated soil water contents by two models were compared with the measured value.
The results showed that the values of root-mean-square-error (RMSE) range from 0.01 to 0.022 cm3/cm3 for APRI-model, and from 0.012 to 0.031 cm3/cm3 for Hydrus-2D model. The average relative error between the simulated and measured soil water content is about 10% for APRI-model,
and from 11% to 29% for Hydrus-2D model, indicating that two models perform well in simulating soil moisture dynamic under
the APDI, but the APRI-model is more suitable for modeling the soil water dynamic in the arid region with greater soil evaporation
and uneven root distribution. 相似文献
999.
1000.
Characterization of rice tryptophan decarboxylases and their direct involvement in serotonin biosynthesis in transgenic rice 总被引:1,自引:0,他引:1
l-Tryptophan decarboxylase (TDC) and l-tyrosine decarboxylase (TYDC) belong to a family of aromatic l-amino acid decarboxylases and catalyze the conversion of tryptophan and tyrosine into tryptamine and tyramine, respectively.
The rice genome has been shown to contain seven TDC or TYDC-like genes. Three of these genes for which cDNA clones were available were characterized to assign their functions using
heterologous expression in Escherichia coli and rice (Oryza sativa cv. Dongjin). The purified products of two of the genes were expressed in E. coli and exhibited TDC activity, whereas the remaining gene could not be expressed in E. coli. The recombinant TDC protein with the greatest TDC activity showed a K
m of 0.69 mM for tryptophan, and its activity was not inhibited by phenylalanine or tyrosine, indicating a high level of substrate
specificity toward tryptophan. The ectopic expression of the three cDNA clones in rice led to the abundant production of the
products of the encoded enzymes, tyramine and tryptamine. The overproduction of TYDC resulted in stunted growth and a lack
of seed production due to tyramine accumulation, which increased as the plant aged. In contrast, transgenic plants that produced
TDC showed a normal phenotype and contained 25-fold and 11-fold higher serotonin in the leaves and seeds, respectively, than
the wild-type plants. The overproduction of either tyramine or serotonin was not strongly related to the enhanced synthesis
of tyramine or serotonin derivatives, such as feruloyltyramine and feruloylserotonin, which are secondary metabolites that
act as phytoalexins in plants. 相似文献