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151.
The use of Escherichia coli bearing a phoN gene for the removal of uranium and nickel from aqueous flows 总被引:1,自引:0,他引:1
G. Basnakova E. R. Stephens M. C. Thaller G. M. Rossolini L. E. Macaskie 《Applied microbiology and biotechnology》1998,50(2):266-272
A Citrobacter sp. originally isolated from metal-polluted soil accumulates heavy metals via metal-phosphate deposition utilizing inorganic
phosphate liberated via PhoN phosphatase activity. Further strain development was limited by the non-transformability of this
environmental isolate. Recombinant Escherichia coli DH5α bearing cloned phoN or the related phoC acquired metal-accumulating ability, which was compared with that of the Citrobacter sp. with respect to removal of uranyl ion (UO2
2+) from dilute aqueous flows and its deposition in the form of polycrystalline hydrogen uranyl phosphate (HUO2PO4). Subsequently, HUO2PO4-laden cells removed Ni2+ from dilute aqueous flows via intercalation of Ni2+ into the HUO2PO4 lattice. Despite comparable acid phosphatase activity in all three strains, the E. coli DH5α (phoN) construct was superior to Citrobacter N14 in both uranyl and nickel accumulation, while the E. coli DH5α (phoC) construct was greatly inferior in both respects. Expression of phosphatase activity alone is not the only factor that permits
efficient and prolonged metal phosphate accumulation, and the data highlight possible differences in the PhoN and PhoC phosphatases,
which are otherwise considered to be related in many respects.
Received: 30 December 1997 / Received revision: 25 March 1998 / Accepted: 26 March 1998 相似文献
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154.
Tools for estimating population structure from genetic data are now used in a wide variety of applications in population genetics. However, inferring population structure in large modern data sets imposes severe computational challenges. Here, we develop efficient algorithms for approximate inference of the model underlying the STRUCTURE program using a variational Bayesian framework. Variational methods pose the problem of computing relevant posterior distributions as an optimization problem, allowing us to build on recent advances in optimization theory to develop fast inference tools. In addition, we propose useful heuristic scores to identify the number of populations represented in a data set and a new hierarchical prior to detect weak population structure in the data. We test the variational algorithms on simulated data and illustrate using genotype data from the CEPH–Human Genome Diversity Panel. The variational algorithms are almost two orders of magnitude faster than STRUCTURE and achieve accuracies comparable to those of ADMIXTURE. Furthermore, our results show that the heuristic scores for choosing model complexity provide a reasonable range of values for the number of populations represented in the data, with minimal bias toward detecting structure when it is very weak. Our algorithm, fastSTRUCTURE, is freely available online at http://pritchardlab.stanford.edu/structure.html. 相似文献
155.
This paper, written by two social scientists, presents a social science perspective on the issues raised at the FRAME symposium on Human Alternatives to Animal Studies. Drawing upon the authors' experience of conducting research with stem cell scientists, issues around access to human tissue for in vitro uses are considered. The paper concludes by raising questions pertinent to both interested social scientists and the Three Rs agenda. 相似文献
156.
S Patyar R Joshi DS Prasad Byrav A Prakash B Medhi BK Das 《Journal of biomedical science》2010,17(1):21
Resistance to conventional anticancer therapies in patients with advanced solid tumors has prompted the need of alternative
cancer therapies. Moreover, the success of novel cancer therapies depends on their selectivity for cancer cells with limited
toxicity to normal tissues. Several decades after Coley's work a variety of natural and genetically modified non-pathogenic
bacterial species are being explored as potential antitumor agents, either to provide direct tumoricidal effects or to deliver
tumoricidal molecules. Live, attenuated or genetically modified non-pathogenic bacterial species are capable of multiplying
selectively in tumors and inhibiting their growth. Due to their selectivity for tumor tissues, these bacteria and their spores
also serve as ideal vectors for delivering therapeutic proteins to tumors. Bacterial toxins too have emerged as promising
cancer treatment strategy. The most potential and promising strategy is bacteria based gene-directed enzyme prodrug therapy.
Although it has shown successful results in vivo yet further investigation about the targeting mechanisms of the bacteria are required to make it a complete therapeutic approach
in cancer treatment. 相似文献
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Christopher A. Sellick David Knight Alexandra S. Croxford Arfa R. Maqsood Gill M. Stephens Royston Goodacre Alan J. Dickson 《Metabolomics : Official journal of the Metabolomic Society》2010,6(3):427-438
In this study we report on the optimisation of the technologies for generation of a global metabolomics profile for intracellular
metabolites in Chinese hamster ovary (CHO) cells. We evaluated the effectiveness of a range of different extraction methods
applied to CHO cells which had been quenched using a previously optimised approach. The extraction methods tested included
cold methanol, hot ethanol, acid, alkali and methanol/chloroform plus combinations of these. The extraction of metabolites
using two 100% methanol extractions followed by a final water extraction recovered the largest range of metabolites. For the
majority of metabolites, extracts generated in this manner exhibited the greatest recovery with high reproducibility. Therefore,
this was the best extraction method for attaining a global metabolic profile from a single sample. However, another parallel
extraction method (e.g. alkali) may also be required to maximise the range of metabolites recovered (e.g. non-polar metabolites). 相似文献
159.
Jim M Dunwell Mike J Wilkinson Stephen Nelson Sri Wening Andrew C Sitorus Devi Mienanti Yuzer Alfiko Adam E Croxford Caroline S Ford Brian P Forster Peter DS Caligari 《BMC plant biology》2010,10(1):1-25