全文获取类型
收费全文 | 1219篇 |
免费 | 66篇 |
出版年
2021年 | 12篇 |
2020年 | 8篇 |
2019年 | 6篇 |
2018年 | 19篇 |
2017年 | 12篇 |
2016年 | 17篇 |
2015年 | 37篇 |
2014年 | 42篇 |
2013年 | 47篇 |
2012年 | 74篇 |
2011年 | 68篇 |
2010年 | 43篇 |
2009年 | 32篇 |
2008年 | 56篇 |
2007年 | 38篇 |
2006年 | 47篇 |
2005年 | 41篇 |
2004年 | 53篇 |
2003年 | 40篇 |
2002年 | 38篇 |
2001年 | 29篇 |
2000年 | 40篇 |
1999年 | 28篇 |
1998年 | 20篇 |
1997年 | 18篇 |
1996年 | 18篇 |
1995年 | 12篇 |
1994年 | 11篇 |
1993年 | 12篇 |
1992年 | 28篇 |
1991年 | 14篇 |
1990年 | 24篇 |
1989年 | 30篇 |
1988年 | 31篇 |
1987年 | 23篇 |
1986年 | 22篇 |
1985年 | 25篇 |
1984年 | 21篇 |
1983年 | 14篇 |
1982年 | 12篇 |
1981年 | 14篇 |
1980年 | 8篇 |
1979年 | 17篇 |
1978年 | 13篇 |
1975年 | 8篇 |
1974年 | 8篇 |
1973年 | 10篇 |
1972年 | 7篇 |
1971年 | 5篇 |
1970年 | 11篇 |
排序方式: 共有1285条查询结果,搜索用时 15 毫秒
931.
S-O. Olsson P. Baekbo S. Ö. Hansson H. Rautala O. Østerås 《Acta veterinaria Scandinavica》2001,42(Z1):S51
Disease recording of cattle is compulsory in Sweden and Norway. Sweden and Denmark also have mandatory disease recording for swine, whereas Finland and Norway only have compulsory recording of infectious diseases. Both compulsory and voluntary systems are databased, the first ones developed in the 1970's.Disease recording at pig slaughtering is somewhat older. The veterinary practitioner, and often also the farmer, can report treated cases as well as fertility disturbances to the systems. Disease recording at slaughter is carried out by veterinarians and inspection officers. The databases are handled by the veterinary authorities or the agricultural organisations in each country. Costs are defrayed by the authorities and/or the agricultural industry. The farmers receive periodic reports. Data are stored for three to ten years, often longer. Affiliation to animal health schemes for cattle or swine is voluntary. In Sweden and Denmark (cattle) they are run within the scope of government regulations. Affiliation to animal health programmes may also be demanded by organisations within the agricultural industry. These organisations are also responsible for the administration of the programmes. Costs to take part in herd health schemes are covered by the farmers themselves. In certain cases, grants are received from agricultural organisations, authorities, or the European Union. Recording of diseases and the format of animal health schemes in the Nordic countries are described here in order to illustrate the possibilities to compare data between countries. 相似文献
932.
933.
Regulation of mRNA levels for cellular retinol binding protein in rat Sertoli cells by cyclic AMP and retinol 总被引:3,自引:0,他引:3
W Eskild O Oyen S Beebe T Jahnsen V Hansson 《Biochemical and biophysical research communications》1988,152(3):1504-1510
The levels of mRNA for cellular retinol binding protein (CRBP) were studied in primary rat Sertoli cell cultures treated with cAMP analogues and retinol. In the presence of cyclic AMP analogues a dose- and time-dependent reduction (70-90%) of the levels of mRNA for CRBP was observed. Retinol concentrations above 10 nM induced a dose- and time-dependent increase (2-3 fold) in mRNA levels for CRBP. Assuming that CRBP is important for vitamin A action, our data indicate that both cAMP and retinol itself modulate the sensitivity of the Sertoli cells for retinol. 相似文献
934.
Lundin B Hansson M Schoefs B Vener AV Spetea C 《The Plant journal : for cell and molecular biology》2007,49(3):528-539
The extrinsic photosystem II (PSII) protein of 33 kDa (PsbO), which stabilizes the water-oxidizing complex, is represented in Arabidopsis thaliana (Arabidopsis) by two isoforms. Two T-DNA insertion mutant lines deficient in either the PsbO1 or the PsbO2 protein were retarded in growth in comparison with the wild type, while differing from each other phenotypically. Both PsbO proteins were able to support the oxygen evolution activity of PSII, although PsbO2 was less efficient than PsbO1 under photoinhibitory conditions. Prolonged high light stress led to reduced growth and fitness of the mutant lacking PsbO2 as compared with the wild type and the mutant lacking PsbO1. During a short period of treatment of detached leaves or isolated thylakoids at high light levels, inactivation of PSII electron transport in the PsbO2-deficient mutant was slowed down, and the subsequent degradation of the D1 protein was totally inhibited. The steady-state levels of in vivo phosphorylation of the PSII reaction centre proteins D1 and D2 were specifically reduced in the mutant containing only PsbO2, in comparison with the mutant containing only PsbO1 or with wild-type plants. Phosphorylation of PSII proteins in vitro proceeded similarly in thylakoid membranes from both mutants and wild-type plants. However, dephosphorylation of the D1 protein occurred much faster in the thylakoids containing only PsbO2. We conclude that the function of PsbO1 in Arabidopsis is mostly in support of PSII activity, whereas the interaction of PsbO2 with PSII regulates the turnover of the D1 protein, increasing its accessibility to the phosphatases and proteases involved in its degradation. 相似文献
935.
Lotta Fornander Tom Brismar Thomas Hansson Heidi Wikström 《Somatosensory & motor research》2016,33(3-4):178-185
We have previously shown age- and time-dependent effects on brain activity in the primary somatosensory cortex (SI), in a functional magnetic resonance imaging (fMRI) study of patients with median nerve injury. Whereas fMRI measures the hemodynamic changes in response to increased neural activity, magnetoencephalography (MEG) offers a more concise way of examining the evoked response, with superior temporal resolution. We therefore wanted to combine these imaging techniques to gain additional knowledge of the plasticity processes in response to median nerve injury. Nine patients with median nerve trauma at the wrist were examined with MEG. The N1 and P1 responses at stimulation of the injured median nerve at the wrist were lower in amplitude compared to the healthy side (p?.04). Ulnar nerve stimulation of the injured hand resulted in larger N1 amplitude (p?.04). The amplitude and latency of the response did not correlate with the sensory discrimination ability. There was no correlation between N1 amplitude and size of cortical activation in fMRI. There was no significant difference in N1 latency between the injured and healthy median nerve. N1 latency correlated positively with age in both the median and ulnar nerve, and in both the injured and the healthy hand (p?.02 or p?.001). It is concluded that conduction failure in the injured segment of the median nerve decreases the amplitude of the MEG response. Disinhibition of neighboring cortical areas may explain the increased MEG response amplitude to ulnar nerve stimulation. This can be interpreted as a sign of brain plasticity. 相似文献
936.
Immunohistochemical localization of thioredoxin and thioredoxin reductase in adult rats 总被引:5,自引:0,他引:5
Rabbit antisera against homogeneous rat liver thioredoxin and thioredoxin reductase (NADPH-oxidized thioredoxin oxidoreductase, E.C. 1.6.4.5) were prepared and used for immunohistochemical analysis in adult rats. Immunoreactive thioredoxin and thioredoxin reductase were widely distributed in tissues and organs, but varied a lot between cell types. Generally, epithelial cells, neuronal cells and secretory cells, both exocrine and endocrine, showed high immunoreactivity whereas mesenchymal cells with exceptions showed low activity. Surface lining epithelial and keratinizing cells showed high activity. The immunofluorescence was localized in the cytoplasm of cells with enrichments at secretory granules, at the plasma membrane or in the subplasma membrane zone. Variations in secretory cells were seen related to feeding and starvation and to metabolic activity. The distribution of thioredoxin and thioredoxin reductase is compatible with function in thiol-disulfide interchange reaction related to protein synthesis, intracellular transport and different forms of secretion. 相似文献
937.
938.
Rapid characterization of mucin oligosaccharides from rat small intestine with gas chromatography-mass spectrometry 总被引:1,自引:0,他引:1
Mucin glycopeptides were isolated from rat small intestinal mucosa after reduction/alkylation, trypsin digestion and gel chromatography. The oligosaccharides were released by using alkaline-NaBH4, separated into neutral and acidic species and permethylated. The derivatized mixtures were analysed with fast atom bombardment mass spectrometry and gas chromatography-mass spectrometry using thin film columns. Permethylated neutral oligosaccharides with up to seven sugars could be chromatographed and detected with mass spectrometry. The complex mixture revealed was partly due to the linkage GalNAc being substituted at both position 3 and 6. The approach will be very useful when analysing small amounts of mucins and mucin fragments. 相似文献
939.
Gran K. Hansson Elisabeth Lagerstedt Anders Bengtsson Mats Heideman 《Experimental cell research》1987,170(2):338-350
The cellular plasma membrane becomes permeable to macromolecules during the cell injury process. This results in exposure of the interior of the cell to plasma proteins and to high-affinity binding of the Fc part of IgG to intermediate filaments (Hansson, G K, Starkebaum, G A, Benditt, E P & Schwartz, S M, Proc natl acad sci USA 81 (1984) 3103). Such IgG binding could be an early step in a process that serves to eliminate the injured cell. We have now identified its effect on the complement system. Intermediate filaments were reconstituted in vitro from purified vimentin, and incubated with plasma proteins. Cross-linker experiments showed binding of the heavy chain of IgG to vimentin, indicating that the vimentin protein carries an Fc-binding site. In contrast, no direct binding of complement factor Clq to vimentin could be detected. Binding of both IgG and Clq could, however, be detected by immunofluorescence when cytoskeletons of cultured endothelial cells were incubated with fresh serum. Therefore, IgG binding to filaments in the presence of serum is accompanied by Clq binding to IgG. This was in turn followed by fixation of C4 and C3 to intermediate filaments in a process that was dependent on both Ca2+, Mg2+ and Clq, indicating that it was part of a complement activation via the classical pathway. Exposure of fresh serum to intermediate filaments also resulted in production of the anaphylatoxic complement cleavage fragment. C3a, with a dose-response relationship between the amount of filaments present and the amount of C3a generated. Chemotactic activity towards granulocytes and monocytes was also generated by exposure of serum to intermediate filaments, and this activity was dependent on the presence of complement factor C5 and on the classical complement activation cascade, implying that it was due to the C5a peptide. Exposure of the interior of the cell to plasma proteins thus results in binding of IgG to intermediate filaments and activation of the complement cascade via the classical pathway. This, in turn generates bioactive mediators which may recruit leukocytes to the injured cell (C5a) and have profound effects on vascular permeability (C3a, C5a). We propose that this is part of a scavenger mechanism for the elimination of damaged cells. 相似文献
940.
Different cellular distribution of thioredoxin and subunit M1 of ribonucleotide reductase in rat tissues 总被引:1,自引:0,他引:1
Hans-Arne Hansson Bjrn Rozell Sten Stemme Ylva Engstrm Lars Thelander Arne Holmgren 《Experimental cell research》1986,163(2):363-369
The cellular distribution of thioredoxin and protein M1 of ribonucleotide reductase in adult rat tissues was investigated with immunohistochemical techniques using specific antisera. Tissues with high or low frequency of either mitotic or meiotic cell divisions were compared. Thioredoxin was demonstrated in many cells types that showed no detectable protein M1 of ribonucleotide reductase. A few cell types with protein M1 immunoreactivity also contained immunoreactive thioredoxin. However, in most cells no such co-localization could be demonstrated. This lack of correlation between cells containing subunit M1 of ribonucleotide reductase and the thioredoxin indicates that thioredoxin is not the physiologist hydrogen donor for ribonucleotide reductase in rat tissues and that the expression of two enzymes is differently regulated. 相似文献