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101.
Determination of nifedipine in human plasma by flow-injection tandem mass spectrometry 总被引:1,自引:0,他引:1
Jan Dankers Jos van den Elshout Gertrude Ahr Erich Brendel Cees van der Heiden 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》1998,710(1-2):115-120
For use in clinical studies, a fast and sensitive assay method was developed for the determination of nifedipine in human plasma samples. The assay method is based on tandem mass spectrometry detection (HPLC–MS–MS). The effect of flow injection as well as HPLC separation on the results of the nifedipine determination were evaluated. The limit of quantification is 0.5 ng/ml and the accuracy (as determined by spiking recovery) was found to be good. 相似文献
102.
Martin Roos Ernst Pittenauer Erich Schmid Manfred Beyer Bernhard Reinike Günter Allmaier Harald Labischinski 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》1998,705(2):M499
Reversed-phase high-performance liquid chromatography (RP-HPLC) of muropeptides, obtained by muramidase digestion of peptidoglycan in combination with amino acid analysis and plasma desorption time-of-flight mass spectrometry is today by far the best tool to analyze the fine structure of the peptidoglycans. Here we report further improvements of the RP-HPLC separation of muropeptides for analyzing the peptidoglycans of various methicillin-resistant strains of Staphylococcus aureus, with emphasis on a more detailed characterization of the interpeptide bridge of the peptidoglycans of this species. 相似文献
103.
Relationship between T-wave amplitude and oxygen pulse in guinea pigs in hyperbaric helium and hydrogen 总被引:1,自引:0,他引:1
Kayar Susan R.; Parker Erich C.; Aukhert Eugenia O. 《Journal of applied physiology》1998,85(3):798-806
Diving isknown to induce a change in the amplitude of the T wave(ATw) ofelectrocardiograms, but it is unknown whether this is linked to achange in cardiovascular performance. We analyzed ATw in guinea pigs at 10-60atm and 25-36°C, breathing 2%O2 in either helium (heliox;n = 10) or hydrogen (hydrox;n = 9) for 1 h at each pressure. Coretemperature and electrocardiograms were detected by using implantedradiotelemeters. O2 consumption rate was measured by using gas chromatography. In a previous study (S. R. Kayar and E. C. Parker. J. Appl.Physiol. 82: 988-997, 1997), we analyzed theO2 pulse, i.e., theO2 consumption rate per heartbeat, in the same animals. By multivariate regression analysis, weidentified variables that were significant toO2 pulse: body surface area,chamber temperature, core temperature, and pressure. In this study,inclusion of ATw made asignificantly better model with fewer variables. After normalizing forchamber temperature and pressure, theO2 pulse increased with increasing ATw in heliox(P = 0.001) but with decreasingATw in hydrox(P < 0.001). ThusATw is associated with thedifferences in O2 pulse foranimals breathing heliox vs. hydrox. 相似文献
104.
105.
Philine G. D. Feulner Frédéric J. J. Chain Mahesh Panchal Yun Huang Christophe Eizaguirre Martin Kalbe Tobias L. Lenz Irene E. Samonte Monika Stoll Erich Bornberg-Bauer Thorsten B. H. Reusch Manfred Milinski 《PLoS genetics》2015,11(2)
The patterns of genomic divergence during ecological speciation are shaped by a combination of evolutionary forces. Processes such as genetic drift, local reduction of gene flow around genes causing reproductive isolation, hitchhiking around selected variants, variation in recombination and mutation rates are all factors that can contribute to the heterogeneity of genomic divergence. On the basis of 60 fully sequenced three-spined stickleback genomes, we explore these different mechanisms explaining the heterogeneity of genomic divergence across five parapatric lake and river population pairs varying in their degree of genetic differentiation. We find that divergent regions of the genome are mostly specific for each population pair, while their size and abundance are not correlated with the extent of genome-wide population differentiation. In each pair-wise comparison, an analysis of allele frequency spectra reveals that 25–55% of the divergent regions are consistent with a local restriction of gene flow. Another large proportion of divergent regions (38–75%) appears to be mainly shaped by hitchhiking effects around positively selected variants. We provide empirical evidence that alternative mechanisms determining the evolution of genomic patterns of divergence are not mutually exclusive, but rather act in concert to shape the genome during population differentiation, a first necessary step towards ecological speciation. 相似文献
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108.
ZmMYB31 directly represses maize lignin genes and redirects the phenylpropanoid metabolic flux 总被引:4,自引:0,他引:4
Fornalé S Shi X Chai C Encina A Irar S Capellades M Fuguet E Torres JL Rovira P Puigdomènech P Rigau J Grotewold E Gray J Caparrós-Ruiz D 《The Plant journal : for cell and molecular biology》2010,64(4):633-644
Few regulators of phenylpropanoids have been identified in monocots having potential as biofuel crops. Here we demonstrate the role of the maize (Zea mays) R2R3-MYB factor ZmMYB31 in the control of the phenylpropanoid pathway. We determined its in vitro consensus DNA-binding sequence as ACC(T)/(A) ACC, and chromatin immunoprecipitation (ChIP) established that it interacts with two lignin gene promoters in vivo. To explore the potential of ZmMYB31 as a regulator of phenylpropanoids in other plants, its role in the regulation of the phenylpropanoid pathway was further investigated in Arabidopsis thaliana. ZmMYB31 downregulates several genes involved in the synthesis of monolignols and transgenic plants are dwarf and show a significantly reduced lignin content with unaltered polymer composition. We demonstrate that these changes increase cell wall degradability of the transgenic plants. In addition, ZmMYB31 represses the synthesis of sinapoylmalate, resulting in plants that are more sensitive to UV irradiation, and induces several stress-related proteins. Our results suggest that, as an indirect effect of repression of lignin biosynthesis, transgenic plants redirect carbon flux towards the biosynthesis of anthocyanins. Thus, ZmMYB31 can be considered a good candidate for the manipulation of lignin biosynthesis in biotechnological applications. 相似文献
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110.
Zhengdong Zhang Luo Wang Sheng Wei Zhensheng Liu Li-E. Wang Erich M. Sturgis Qingyi Wei 《DNA Repair》2010,9(5):558-566
Methylating agents are involved in carcinogenesis, and the DNA repair protein O6-methylguanine-DNA methyltransferase (MGMT) removes methyl group from O6-methylguanine. Genetic variation in DNA repair genes has been shown to contribute to susceptibility to squamous cell carcinoma of the head and neck (SCCHN). We hypothesize that MGMT polymorphisms are associated with risk of SCCHN. In a hospital-based case–control study of 721 patients with SCCHN and 1234 cancer-free controls frequency-matched by age, sex and ethnicity, we genotyped four MGMT polymorphisms, two in exon 3, 16195C > T and 16286C > T and two in the promoter region, 45996G > T and 46346C > A. We found that none of these polymorphisms alone had a significant effect on risk of SCCHN. However, when these four polymorphisms were evaluated together by the number of putative risk genotypes (i.e. 16195CC, 16286CC, 45996GT + TT, and 46346CA + AA), a statistically significantly increased risk of SCCHN was associated with the combined genotypes with three to four risk genotypes, compared with those with zero to two risk genotypes (adjusted odds ratio (OR) = 1.27; 95% confidence interval (CI) = 1.05–1.53). This increased risk was also more pronounced among young subjects (OR = 1.81; 95% CI = 1.11–2.96), men (OR = 1.24; 95% CI = 1.00–1.55), ever smokers (OR = 1.25; 95% = 1.01–1.56), ever drinkers (OR = 1.29; 95% CI = 1.04–1.60), patients with oropharyngeal cancer (OR = 1.45; 95% CI = 1.12–1.87), and oropharyngeal cancer with regional lymph node metastasis (OR = 1.52; 95% CI = 1.16–1.89). In conclusion, our results suggest that any one of MGMT variants may not have a substantial effect on SCCHN risk, but a joint effect of several MGMT variants may contribute to risk and progression of SCCHN, particularly for oropharyngeal cancer, in non-Hispanic whites. 相似文献