全文获取类型
收费全文 | 892篇 |
免费 | 61篇 |
国内免费 | 1篇 |
出版年
2022年 | 7篇 |
2021年 | 17篇 |
2020年 | 8篇 |
2019年 | 8篇 |
2018年 | 6篇 |
2017年 | 9篇 |
2016年 | 11篇 |
2015年 | 30篇 |
2014年 | 40篇 |
2013年 | 46篇 |
2012年 | 53篇 |
2011年 | 52篇 |
2010年 | 41篇 |
2009年 | 29篇 |
2008年 | 51篇 |
2007年 | 41篇 |
2006年 | 37篇 |
2005年 | 38篇 |
2004年 | 54篇 |
2003年 | 44篇 |
2002年 | 38篇 |
2001年 | 21篇 |
2000年 | 15篇 |
1999年 | 9篇 |
1998年 | 11篇 |
1997年 | 7篇 |
1995年 | 8篇 |
1994年 | 11篇 |
1993年 | 9篇 |
1992年 | 9篇 |
1991年 | 10篇 |
1990年 | 11篇 |
1989年 | 7篇 |
1988年 | 6篇 |
1987年 | 7篇 |
1985年 | 7篇 |
1983年 | 13篇 |
1982年 | 8篇 |
1981年 | 7篇 |
1980年 | 9篇 |
1979年 | 6篇 |
1977年 | 5篇 |
1976年 | 5篇 |
1975年 | 5篇 |
1974年 | 10篇 |
1973年 | 5篇 |
1972年 | 6篇 |
1970年 | 6篇 |
1965年 | 5篇 |
1961年 | 5篇 |
排序方式: 共有954条查询结果,搜索用时 171 毫秒
31.
32.
Dong A Xu X Edwards AM;Midwest Center for Structural Genomics;Structural Genomics Consortium Chang C Chruszcz M Cuff M Cymborowski M Di Leo R Egorova O Evdokimova E Filippova E Gu J Guthrie J Ignatchenko A Joachimiak A Klostermann N Kim Y Korniyenko Y Minor W Que Q Savchenko A Skarina T Tan K Yakunin A Yee A Yim V Zhang R Zheng H Akutsu M Arrowsmith C Avvakumov GV Bochkarev A Dahlgren LG Dhe-Paganon S Dimov S Dombrovski L Finerty P Flodin S Flores A Gräslund S Hammerström M Herman MD Hong BS 《Nature methods》2007,4(12):1019-1021
We tested the general applicability of in situ proteolysis to form protein crystals suitable for structure determination by adding a protease (chymotrypsin or trypsin) digestion step to crystallization trials of 55 bacterial and 14 human proteins that had proven recalcitrant to our best efforts at crystallization or structure determination. This is a work in progress; so far we determined structures of 9 bacterial proteins and the human aminoimidazole ribonucleotide synthetase (AIRS) domain. 相似文献
33.
Therese S. Høiem Maria K. Andersen Marta Martin-Lorenzo Rémi Longuespée Britt S.R. Claes Anna Nordborg Frédéric Dewez Benjamin Balluff Marco Giampà Animesh Sharma Lars Hagen Ron M.A. Heeren Tone F. Bathen Guro F. Giskeødegård Sebastian Krossa May-Britt Tessem 《Proteomics》2022,22(10):2100223
MALDI MS imaging (MSI) is a powerful analytical tool for spatial peptide detection in heterogeneous tissues. Proper sample preparation is crucial to achieve high quality, reproducible measurements. Here we developed an optimized protocol for spatially resolved proteolytic peptide detection with MALDI time-of-flight MSI of fresh frozen prostate tissue sections. The parameters tested included four different tissue washes, four methods of protein denaturation, four methods of trypsin digestion (different trypsin densities, sprayers, and incubation times), and five matrix deposition methods (different sprayers, settings, and matrix concentrations). Evaluation criteria were the number of detected and excluded peaks, percentage of high mass peaks, signal-to-noise ratio, spatial localization, and average intensities of identified peptides, all of which were integrated into a weighted quality evaluation scoring system. Based on these scores, the optimized protocol included an ice-cold EtOH+H2O wash, a 5 min heating step at 95°C, tryptic digestion incubated for 17h at 37°C and CHCA matrix deposited at a final amount of 1.8 μg/mm2. Including a heat-induced protein denaturation step after tissue wash is a new methodological approach that could be useful also for other tissue types. This optimized protocol for spatial peptide detection using MALDI MSI facilitates future biomarker discovery in prostate cancer and may be useful in studies of other tissue types. 相似文献
34.
This study examines the occurrence and distribution of epidermal dendritic cells (DCs) in cryostate sections from plantar skin in normal rats and in rats with a crush injury or neurotomy and suture of the sciatic nerve. The dendritic cells were visualized with antibodies against protein-gene product 9.5 (PGP 9.5). Counts under the fluorescence microscope showed that the occurrence of dendritic cells is increased and that the proportion of dendritic cells in the basal layer is elevated 3 months after sciatic neurotomy and suture but not after a crush lesion. The countings also revealed that the number of cells is elevated as soon as 1 week after neurotomy and suture. Labelling with specific antibodies showed that the dendritic cells examined represent Langerhans cells (LCs). These observations show that there is a neural influence on the occurrence and distribution of PGP 9.5-immunoreactive epidermal Langerhans cells. Whether this influence is direct or indirect remains to be ascertained. 相似文献
35.
A method for simultaneously imaging Zn2+ secretion and intracellular Ca2+ at beta-cell clusters and single islets of Langerhans was developed. Cells were loaded with the Ca2+ indicator Fura Red, incubated in buffer containing the Zn2+ indicator FluoZin-3, and imaged via laser scanning fluorescence confocal microscopy. FluoZin-3 and Fura Red are excited at 488 nm and emit at 515 and 665 nm, respectively. Zn2+, which is co-released with insulin, reacts with extracellular FluoZin-3 to form a fluorescent product. Stimulation of cell clusters with glucose evoked increases and oscillations in intracellular Ca2+ and Zn2+ secretion that were correlated with each other and were synchronized among cells. In single islets, spatially resolved dynamics of secretion including detection of first phase, second phase, and synchronized oscillations around the islet were observed. Fura Red did not yield detectable Ca2+ signals at islets. For islet measurements, cells were loaded with Fura-2 and incubated in FluoZin-3 while sequentially illuminating the islets with 340, 380, and 470 nm light and acquiring epi-fluorescence images with a charge-coupled device (CCD) camera. This allowed Ca2+ and secretion to be observed with approximately 2 s temporal resolution. This method should be useful for studying Ca2+ secretion coupling and any application, requiring rapid assays of secretion. 相似文献
36.
We wanted to assess whether B-cell and/or T-cell responses to collagen and thereby the course of collagen-induced arthritis
could be suppressed by regulatory mechanisms associated with oral tolerance to an unrelated protein. DBA/1 mice were fed ovalbumin
(OVA)-containing pellets ad libitum for 1 week and subsequently coimmunized twice, with a mixture of bovine collagen type
II (BCII) and OVA in Freund's complete adjuvant. Mice fed OVA before coimmunization with BCII and OVA had significantly lower
arthritic scores than mice immunized with BCII only. Their body weight increased during the study period and their anti-BCII
antibody activity was significantly IgG2a lower. The frequency of spleen cells producing IgG anti-BCII antibody was also reduced. Coimmunization per se slightly ameliorated
the development of arthritis, resulting in an early, transient reduction. It resulted in significantly higher IgG1 anti-BCII antibody activity and increased splenocyte secretion of IFN-γ and IL-10 in response to BCII. Our findings demonstrate
that OVA-specific regulatory events induced by feeding OVA, i.e. bystander suppression, reduced the severity of arthritis
in animals immunized with BCII and OVA. Anti-BCII specific antibody responses and cytokine secretion by types 1 and 2 T helper
cells were also decreased. 相似文献
37.
Strøm CC Kruhøffer M Knudsen S Stensgaard-Hansen F Jonassen TE Orntoft TF Haunsø S Sheikh SP 《Comparative and Functional Genomics》2004,5(6-7):459-470
Although the molecular signals underlying cardiac hypertrophy have been the subject of intense investigation, the extent of common and distinct gene regulation between different forms of cardiac hypertrophy remains unclear. We hypothesized that a general and comparative analysis of hypertrophic gene expression, using microarray technology in multiple models of cardiac hypertrophy, including aortic banding, myocardial infarction, an arteriovenous shunt and pharmacologically induced hypertrophy, would uncover networks of conserved hypertrophy-specific genes and identify novel genes involved in hypertrophic signalling. From gene expression analyses (8740 probe sets, n = 46) of rat ventricular RNA, we identified a core set of 139 genes with consistent differential expression in all hypertrophy models as compared to their controls, including 78 genes not previously associated with hypertrophy and 61 genes whose altered expression had previously been reported. We identified a single common gene program underlying hypertrophic remodelling, regardless of how the hypertrophy was induced. These genes constitute the molecular basis for the existence of one main form of cardiac hypertrophy and may be useful for prediction of a common therapeutic approach. Supplementary material for this article can be found at: http://www.interscience.wiley.com/jpages/1531-6912/suppmat. 相似文献
38.
Govindarajan S Ness JE Kim S Mundorff EC Minshull J Gustafsson C 《Journal of molecular biology》2003,328(5):1061-1069
During protein evolution, amino acids change due to a combination of functional constraints and genetic drift. Proteins frequently contain pairs of amino acids that appear to change together (covariation). Analysis of covariation from naturally occurring sets of orthologs cannot distinguish between residue pairs retained by functional requirements of the protein and those pairs existing due to changes along a common evolutionary path. Here, we have separated the two types of covariation by independently recombining every naturally occurring amino acid variant within a set of 15 subtilisin orthologs. Our analysis shows that in this family of subtilisin orthologs, almost all possible pairwise combinations of amino acids can coexist. This suggests that amino acid covariation found in the subtilisin orthologs is almost entirely due to common ancestral origin of the changes rather than functional constraints. We conclude that naturally occurring sequence diversity can be used to identify positions that can vary independently without destroying protein function. 相似文献
39.
Bylund J Björstad A Granfeldt D Karlsson A Woschnagg C Dahlgren C 《The Journal of biological chemistry》2003,278(33):30578-30586
In neutrophils, coupling of chemoattractants to their cell surface receptor at low temperature (相似文献
40.
Genetic differences within and between species of deep-sea crabs (chaceon) from the North Atlantic Ocean 总被引:2,自引:0,他引:2
The deep-sea red crab Chaceon quinquedens is a commercially important crustacean on the Atlantic continental shelf and slope of North America. To assess genetic subdivision in C. quinquedens, we examined the nucleotide sequence of the mitochondrial 16S rDNA gene and the internal transcribed spacers (ITS) of the nuclear ribosomal repeat in samples from southern New England and the Gulf of Mexico. We compared those data to sequences from two congeners, a sympatric species from the Florida coast, C. fenneri, and an allopatric eastern Atlantic species, C. affinis. The 16S rDNA data consisted of 379 aligned nucleotides obtained from 37 individuals. The greatest genetic difference among geographical groups or nominal species was between C. quinquedens from southern New England and C. quinquedens from the Gulf of Mexico. Haplotypes from these two groups had a minimum of 10 differences. All 11 C. fenneri samples matched the most common haplotype found in C. quinquedens from the Gulf of Mexico, and this haplotype was not detected in C. quinquedens from southern New England. The three haplotypes of C. affinis were unique to that recognized species, but those haplotypes differed only slightly from those of C. fenneri and C. quinquedens from the Gulf of Mexico. Based on 16S rDNA and ITS data, genetic differences between C. quinquedens from southern New England and the Gulf of Mexico are large enough to conclude that these are different fishery stocks. Our results also indicate that the designation of morphological species within the commercially important genus Chaceon is not congruent with evolutionary history. The genetic similarity of C. affinis from the eastern Atlantic and C. quinquedens from the Gulf of Mexico suggests these trans-Atlantic taxa share a more recent common history than the two populations of "C. quinquedens" that we examined. 相似文献