全文获取类型
收费全文 | 1791篇 |
免费 | 170篇 |
国内免费 | 2篇 |
专业分类
1963篇 |
出版年
2022年 | 23篇 |
2021年 | 29篇 |
2020年 | 15篇 |
2019年 | 17篇 |
2018年 | 40篇 |
2017年 | 32篇 |
2016年 | 39篇 |
2015年 | 70篇 |
2014年 | 84篇 |
2013年 | 110篇 |
2012年 | 146篇 |
2011年 | 115篇 |
2010年 | 64篇 |
2009年 | 69篇 |
2008年 | 96篇 |
2007年 | 102篇 |
2006年 | 88篇 |
2005年 | 79篇 |
2004年 | 76篇 |
2003年 | 77篇 |
2002年 | 80篇 |
2001年 | 26篇 |
1999年 | 19篇 |
1998年 | 21篇 |
1997年 | 21篇 |
1996年 | 20篇 |
1995年 | 11篇 |
1994年 | 12篇 |
1993年 | 16篇 |
1992年 | 18篇 |
1991年 | 16篇 |
1990年 | 11篇 |
1989年 | 15篇 |
1988年 | 15篇 |
1987年 | 16篇 |
1986年 | 15篇 |
1985年 | 28篇 |
1984年 | 14篇 |
1983年 | 10篇 |
1982年 | 13篇 |
1981年 | 16篇 |
1979年 | 14篇 |
1978年 | 13篇 |
1977年 | 13篇 |
1975年 | 14篇 |
1974年 | 9篇 |
1973年 | 14篇 |
1972年 | 11篇 |
1970年 | 9篇 |
1969年 | 9篇 |
排序方式: 共有1963条查询结果,搜索用时 203 毫秒
1.
Ralf Heinrich Peter Bräunig Ismeni Walter Henning Schneider Edward A. Kravitz 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》2000,186(7-8):617-629
In the American lobster (Homarus americanus) the biogenic amines serotonin and octopamine appear to play important and opposite roles in the regulation of aggressive behavior, in the establishment and/or maintenance of dominant and subordinate behavioral states and in the modulation of the associated postural stances and escape responses. The octopamine-containing neurosecretory neurons in the thoracic regions of the lobster ventral nerve cord fall into two morphological subgroups, the root octopamine cells, a classical neurohemal group with release regions along second thoracic roots, and the claw octopamine cells, a group that selectively innervates the claws. Cells of both subgroups have additional sets of endings within neuropil regions of ganglia of the ventral nerve cord. Octopamine neurosecretory neurons generally are silent, but when spontaneously active or when activated, they show large overshooting action potentials with prominent after-hyperpolarizations. Autoinhibition after high-frequency firing, which is also seen in other crustacean neurosecretory cells, is readily apparent in these cells. The cells show no spontaneous synaptic activity, but appear to be excited by a unitary source. Stimulation of lateral or medial giant axons, which excite serotonergic cells yielded no response in octopaminergic neurosecretory cells and no evidence for direct interactions between pairs of octopamine neurons, or between the octopaminergic and the serotonergic sets of neurosecretory neurons was found. 相似文献
2.
3.
The signal sequence suffices to direct export of outer membrane protein OmpA of Escherichia coli K-12. 总被引:8,自引:3,他引:5 下载免费PDF全文
We studied whether information required for export is present within the mature form of the Escherichia coli 325-residue outer membrane protein OmpA. We had previously analyzed overlapping internal deletions in the ompA gene, and the results allowed us to conclude that if such information exists it must be present repeatedly within the membrane part of the protein encompassing amino acid residues 1 to 177 (R. Freudl, H. Schwarz, M. Klose, N. R. Movva, and U. Henning, EMBO J. 4:3593-3598, 1985). A deletion which removed the codons for amino acid residues 1 to 229 of the OmpA protein was constructed. In this construct the signal sequence was fused to the periplasmic part of the protein. The resulting protein, designated Pro-OmpA delta 1-229, was processed, and the mature 95-residue protein accumulated in the periplasm. Hence, information required for export does not exist within the OmpA protein. 相似文献
4.
5.
6.
U. Henning und C. Herz 《Molecular & general genetics : MGG》1964,95(3):260-275
Summary Acetateless mutants ofEscherichia coli K 12 lacking the enzymatic activities either of the carboxylase, the lipoic reductase-transacetylase or of all components of the pyruvate dehydrogenase complex are shown to be the consequence of mutations in the closely linked structural genes for the constituent enzymes of the enzyme complex. This genetic segment (the acetate locus = Ac) was found on theE. coli chromosome between the leucine and TR loci. Acetate and leucine loci are transduced jointly by the phage Plkc. The preparation is described of double mutants carrying two genetic lesions in the pyruvate dehydrogenase structural gene cluster. The mutant sites of 00-type strains have been localized in a part of the carboxylase structural gene corresponding to the left extremity (nearest the leucine locus) of the acetate locus.Studies on possible genetic relationships between the pyruvate and -ketoglutarate dehydrogenases (which regarding the individual reactions catalyzed are very similar and partly identical) revealed that the two -keto acid dehydrogenases most likely do not share any genetic determinant.
Mit 5 Textabbildungen 相似文献
Mit 5 Textabbildungen 相似文献
7.
Restoration of membrane incorporation of an Escherichia coli outer membrane protein (OmpA) defective in membrane insertion 总被引:2,自引:0,他引:2
M Klose F J?hnig I Hindennach U Henning 《The Journal of biological chemistry》1989,264(36):21842-21847
The mechanism of sorting, to the outer membrane, of the 325-residue Escherichia coli protein OmpA has been investigated. It is thought to traverse the membrane eight times in antiparallel beta-strands, forming an amphiphilic beta-barrel which encompasses residues 1 to about 170; the COOH-terminal moiety is periplasmic. A mutant, carrying the substitutions Leu164----Pro and Val166----Asp within the last beta-strand (residues 160-170), has been described which was unable to assemble in the membrane (Klose, M., MacIntyre, S., Schwarz, H., and Henning, U. (1988) J. Biol. Chem. 263, 13297-13302). Linkers were inserted between the codons for residues 164 and 165 of the mutant protein. Of 13 different genes recovered, five encoded proteins which had regained the ability to assemble in the membrane. The properties of the mutant proteins, together with a structure prediction method, indicate the following rules for the final beta-strand to be compatible with, or possibly initiate, membrane insertion: (i) it must be amphiphilic or hydrophobic while its primary structure as such is fairly unimportant, (ii) it must extend over at least 9 residues, and (iii) it must not contain a proline residue around its center. One of the genes recovered coded for OmpA up to residue 164 and then followed by 10 linker-encoded residues. This 174-residue polypeptide was assembled in the membrane but did not, in contrast to all other proteins, expose sites sensitive to trypsin at the inner face of the membrane. This behavior agrees perfectly well with the OmpA model. 相似文献
8.
Frieder Schauer Kirsten Henning Helmut Pscheidl Rolf M. Wittich Peter Fortnagel Heinz Wilkes Volker Sinnwell Wittko Francke 《Biodegradation》1995,6(2):173-180
Trichosporon beigelii SBUG 752 was able to transform diphenyl ether. By TLC, HPLC, GC, GC-MS, NMR- and UV-spectroscopy, several oxidation products were identified. The primary attack was initiated by a monooxygenation step, resulting in the formation of 4-hydroxydiphenyl ether, 2-hydroxydiphenyl ether and 3-hydroxydiphenyl ether (48:47:5). Further oxidation led to 3,4-dihydroxydiphenyl ether. As a characteristic product resulting from the cleavage of an aromatic ring, the lactone of 2-hydroxy-4-phenoxymuconic acid was identified. The possible mechanism of ring cleavage to yield this metabolite is discussed. 相似文献
9.
10.