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21.
Brain Quinolinic Acid in Chronic Experimental Hepatic Encephalopathy: Effects of an Exogenous Ammonium Acetate Challenge 总被引:1,自引:1,他引:0
Peter B. F. Bergqvist Melvyn P. Heyes †Mogens Bugge Finn Bengtsson 《Journal of neurochemistry》1995,65(5):2235-2240
Abstract: Elevated brain concentrations of the neurotoxin and NMDA receptor agonist quinolinic acid (QUIN) have been demonstrated in portacaval-shunted (PCS) rats, a chronic hepatic encephalopathy (HE) model. Increased brain QUIN levels have also been shown in acute hyperammonemic rats. In the present study, the plasma and brain (neocortical) QUIN levels in chronic PCS rats were investigated. The study also included a single exogenous ammonium acetate (NH4 Ac; 5.2 mmol/kg, i.p.) challenge to precipitate a reversible hepatic coma. Compared with sham-operated controls, chronic PCS rats exhibited decreased rather than increased plasma and brain QUIN levels. The plasma-to-brain QUIN ratio was not found to be altered. The NH4 Ac administration induced coma in all of the PCS rats 20–25 min after the challenge, and this coma was resolved within 60–75 min. No relevant temporal relationship between changes in brain QUIN levels and the neurological status in the PCS rats was observed. Therefore, our results do not support the contention that increased brain QUIN levels per se are involved in the pathogenesis of HE. 相似文献
22.
J. C. du Preez M. Immelman J. L. F. Kock S. G. Kilian 《World journal of microbiology & biotechnology》1997,13(1):81-87
The effect of different initial acetic acid concentrations on the growth of and lipid and gamma-linolenic acid (GLA) production
byMucor circinelloides CBS 203.28 was determined in a 14 litre stirred tank reactor operated in a fedbatch, pH-stat mode with acetic acid as carbon
source and pH titrant. Increased acetic acid concentrations in the culture resulted in a significant increase in the crude
oil content of the biomass. By contrast, all the other parameters such as the biomass concentration, GLA and oil yield on
acetic acid, the GLA content of the biomass and oil, the growth rate and volumetric rate of GLA production decreased with
an increase in acetic acid concentration. The best results were obtained with acetic acid at 2 g/1, which gave 39.8 mg GLA/g
biomass and 15.6% GLA in the neutral lipid fraction, amounting to 340 mg GLA/1 culture. A decrease in the glyco- and phospho-lipid
fractions during the cultivation coincided with an increase in the neutral lipid fraction. The GLA content of the biomass
remained within rather narrow limits of 3.5% to 4% of the biomass, irrespective of the oil content of the biomass. The fatty
acid profile was not greatly affected by the acetic acid concentration. The hyphae of the fungus were characterized by the
accumulation of large intracellular oil droplets and some septa delimited the hyphae. 相似文献
23.
Rice-barley synteny and its application to saturation mapping of the barley Rpg1 region. 总被引:4,自引:0,他引:4 下载免费PDF全文
A Kilian D A Kudrna A Kleinhofs M Yano N Kurata B Steffenson T Sasaki 《Nucleic acids research》1995,23(14):2729-2733
In order to facilitate the map-based cloning of the barley stem rust resistance gene Rpg1, we have demonstrated a high degree of synteny at a micro level between the telomeric region of barley chromosome 1P and rice chromosome 6. We have also developed and applied a simple and efficient method for selecting useful probes from large insert genomic YAC and cosmid clones. The gene order within the most terminal 6.5 cM of barley chromosome 1P was compared with the most terminal 2.7 cM of rice chromosome 6. Nine rice probes, previously mapped in rice or isolated from YAC or cosmid clones from this region, were mapped in barley. All, except one, were in synteny with the rice gene order. The exception, probe Y617R, was duplicated in barley. One copy was located on a different chromosome and the other in a non-syntenic position on barley chromosome 1P. The barley probes from this region could not be mapped to rice, but two of them were inferred to be in a syntenic location based on their position on a rice YAC. This work demonstrates the utility of applying the results of genetic and physical mapping of the small genome cereal rice to map-based cloning of interesting genes from large genome relatives. 相似文献
24.
Jesper Hald Niels Rasmussen Mogens H. Claesson 《Cancer immunology, immunotherapy : CII》1995,41(4):243-250
Tumour-infiltrating lymphocytes (TIL) and tumours from six patients with squamous cell carcinomas of the head and neck (SCCHN) were investigated. The six tumours all expressed major histocompatibility complex (MHC) class I antigens both in vivo and as tumor cell lines grown in vitro. In addition, the cancer cells either overexpressed the tumour-suppressor gene product p53 or harboured human papilloma virus 16/18 (HPV). The TIL were expanded in vitro in the presence of interleukin-2, immobilised anti-CD3 mAb and soluble anti-CD28 mAb. Expanded TIL cultures contained both CD4+and CD8+T cells, but generally contained few CD56+CD3-cells of the natural killer (NK) phenotype. CD8+T cells dominated the individual TIL cultures from five of the six patients and showed significant autologous tumour cell lysis. In TIL cultures derived from four of these tumour-reactive TIL cultures, killing could be partially blocked by an anti-MHC class I mAb. TIL cultures reacting with autologous tumour cells also showed strong TCR/CD3-redirected cytotoxicity when assayed against hybridoma cells expressing anti-TCR/CD3 mAb as well as natural-killer(NK)-like activity. A number of TIL cultures devoid of autologous tumour cell lysis were capable of lysing the natural-killer(NK)-sensitive K562 cell line suggesting that the SCCHN cells themselves are resistant to NK-like lysis. In conclusion, TIL cultures from head and neck carcinomas contain T cells which, upon expansion in vitro, can lyse autologous tumour cells in a MHC-class-I-restricted fashion. Thus, the results of the present study document that carcinomas of the head and neck in some patients are infiltrated by cytotoxic T cell precursors potentially capable of rejecting the autologous tumour. 相似文献
25.
R.Douglas Carter Robert E. Hardy Kilian Dill 《International journal of biological macromolecules》1984,6(3):164-166
The 13C resonances of Nα,N-[13C]dimethylserine of partially 13C reductively methylated glycophorin AM were monitored as a function of pH at 45°C. For comparison, limited data are also presented for the pH dependence of the 13C resonances of Nα,N- [13C]dimethylserine of fully 13C reductively methylated deglycosylated glycophorin AM. The ‘major’ component of Nα,N- [13C]dimethylserine of glycophorin AM did not titrate, whereas the ‘minor’ component titrated with a pKa of 7.80 (Hill coefficient of 0.95). Similar results are also indicated for the Nα,N- [13C]dimethylserine resonances of 13C reductively methylated deglycosylated glycophorin AM. 相似文献
26.
Stephen C. Wood Mogens L. Glass Kjell Johansen 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1977,116(3):287-296
Summary Ventilation, gas exchange, blood gas tensions and arterial pH were measured simultaneously in monitor lizards,Varanus exanthematicus. In contrast to previously studied poikilotherms, the arterial pH is independent of body temperature within the normally encountered temperature range (Fig. 1). This exception to the relative alkalinity concept (Rahn, 1966) is correlated with the finding thatV. exanthematicus maintains a constant ratio of ventilation to oxygen uptake (and CO2 production) at different temperatures (Fig. 3). The increase in arterial
(Fig. 1) is related to an increase in physiological dead space; i.e., alveolar ventilation increases less with temperature than total ventilation (Fig. 4). This may result from the increased frequency of breathing which results in a reduced breath holding time (Fig. 2). Varanid lizards have a higher oxygen requirement than other reptiles. This is reflected in the control of ventilation, the specialized lung morphology, the high arterial saturation due to low intracardiac shunting, pH regulation and other mammal-like features ofVaranus. 相似文献
27.
Marsha E. Daman Ron L. Batstone-Cunningham Robert E. Hardy Kilian Dill 《International journal of biological macromolecules》1983,5(6):371-373
13C-n.m.r. spectral data for 13C reductively methylated intact homozygous and heterozygous glycophorins A were compared with the 13C-n.m.r. spectral data for the 13C reductively methylated homozygous and heterozygous N-terminal glycopeptides derived from the trypsin digest of glycophorin A. The results indicate that pronounced aggregation of this glycoprotein in solution does not affect the structural differences that we have previously observed for glycophorins AM and AN at and/or near the N-terminal amino acid. Moreover, the data suggest that two structural states exist for glycophorin AM. 相似文献
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