全文获取类型
收费全文 | 1050篇 |
免费 | 56篇 |
专业分类
1106篇 |
出版年
2022年 | 8篇 |
2021年 | 13篇 |
2020年 | 9篇 |
2019年 | 10篇 |
2018年 | 9篇 |
2016年 | 24篇 |
2015年 | 22篇 |
2014年 | 25篇 |
2013年 | 37篇 |
2012年 | 51篇 |
2011年 | 39篇 |
2010年 | 24篇 |
2009年 | 19篇 |
2008年 | 41篇 |
2007年 | 47篇 |
2006年 | 32篇 |
2005年 | 35篇 |
2004年 | 37篇 |
2003年 | 31篇 |
2002年 | 30篇 |
2001年 | 25篇 |
2000年 | 37篇 |
1999年 | 19篇 |
1997年 | 11篇 |
1996年 | 7篇 |
1993年 | 7篇 |
1992年 | 18篇 |
1991年 | 10篇 |
1990年 | 12篇 |
1989年 | 12篇 |
1988年 | 15篇 |
1987年 | 12篇 |
1986年 | 10篇 |
1984年 | 8篇 |
1983年 | 7篇 |
1982年 | 8篇 |
1981年 | 7篇 |
1979年 | 13篇 |
1978年 | 7篇 |
1976年 | 7篇 |
1975年 | 24篇 |
1974年 | 21篇 |
1973年 | 18篇 |
1972年 | 10篇 |
1971年 | 49篇 |
1970年 | 11篇 |
1969年 | 19篇 |
1968年 | 25篇 |
1967年 | 9篇 |
1966年 | 9篇 |
排序方式: 共有1106条查询结果,搜索用时 11 毫秒
51.
Polymorphism of red cell glyoxalase I (EI: 4.4.1.5); a new genetic marker in man. Investigation of 169 mother-child combinations. 总被引:10,自引:0,他引:10
The polymorphism of glyoxalase I was investigated in 169 mother-child combinations from southwestern Germany. Glyoxalase I (GLO) has 3 common phenotypes: GLO 1, GLO 2-1, and GLO 2. The results are in good agreement with the formal hypothesis: Two alleles GLO1 and GLO2 at an autosomal locus. The GLO1 gene frequency was estimated to be 0.39. From the electrophoretic pattern the GLO-molecule appears to consist of two subunits. 相似文献
52.
Kimberley B. Ritter David R. Jordan Scott C. Chapman Ian D. Godwin Emma S. Mace C. Lynne McIntyre 《Molecular breeding : new strategies in plant improvement》2008,22(3):367-384
QTL for stem sugar-related and other agronomic traits were identified in a converted sweet (R9188) × grain (R9403463-2-1)
sorghum population. QTL analyses were conducted using phenotypic data for 11 traits measured in two field experiments and
a genetic map comprising 228 SSR and AFLP markers grouped into 16 linkage groups, of which 11 could be assigned to the 10
sorghum chromosomes (SBI-01 to SBI-10). QTL were identified for all traits and were generally co-located to five locations
(SBI-01, SBI-03, SBI-05, SBI-06 and SBI-10). QTL alleles from R9188 were detected for increased sucrose content and sugar
content on SBI-01, SBI-05 and SBI-06. R9188 also contributed QTL alleles for increased Brix on SBI-05 and SBI-06, and increased
sugar content on SBI-03. QTL alleles from R9403463-2-1 were found for increased sucrose content and sucrose yield on SBI-10,
and increased glucose content on SBI-07. QTL alleles for increased height, later flowering and greater total dry matter yield
were located on SBI-01 of R9403463-2-1, and SBI-06 of R9188. QTL alleles for increased grain yield from both R9403463-2-1
and R9188 were found on SBI-03. As an increase in stem sugars is an important objective in sweet sorghum breeding, the QTL
identified in this study could be further investigated for use in marker-assisted selection of sweet sorghum. 相似文献
53.
Simasko SM Ritter RC 《American journal of physiology. Gastrointestinal and liver physiology》2003,285(6):G1204-G1213
Patch-clamp electrophysiological methods were used on dissociated rat nodose neurons maintained in culture to determine whether responses to cholecystokinin (CCK) were associated with capsaicin-resistant (A type) or capsaicin-sensitive (C type) neurons. Nodose neurons were classified as A or C type on the basis of the characteristics of the Na+ current, a hyperpolarization-activated current, and sensitivity to a low concentration of capsaicin to ascertain the presence of vanilloid receptor 1 that has been associated with C-type neurons in sensory ganglia. It was expected that only capsaicin-sensitive C-type neurons would respond to CCK, because most vagally mediated actions of CCK are blocked by capsaicin treatment. However, we found that subpopulations of both A- and C-type neurons responded to CCK (24 and 38%, respectively). Thus some vagally mediated actions of CCK may be mediated by capsaicin insensitive A-type neurons. 相似文献
54.
Identification,purification, and characterization of pathogenesis-related proteins from virus-infected Samsun NN tobacco leaves 总被引:5,自引:0,他引:5
Ten pH-3 soluble, low-molecular-weight pathogenesis-related proteins (PRs) were found to accumulate in leaves of tobacco cv. Samsun NN reacting hypersensitively to tobacco mosaic virus. Besides the previously characterized PRs 1a, 1b, 1c and 2, these proteins were provisionally designated N, O, P, Q, R, and S in order of decreasing electrophoretic mobility in native polyacrylamide gels. Two-dimensional gel electrophoresis indicated that the PRs consist of single polypeptides, except for R, which is composed of two components with slightly different molecular weights. Estimated molecular weights in SDS-containing gels were: PRs 1a and 1b 17 kD, 1c 16.5 kD, 2 31 kD, N 33 kD, O 35 kD, P 27 kD, Q 28 kD, R 13 and 15 kD, and S 25 kD. However, based on their elution from gel filtration columns and relative moblities in native gels of different acrylamide concentrations, P and Q appeared to have molecular weights similar to those of the PR 1 group. Upon chromatofocusing no additional components were resolved. The PRs were eluted between pH 7 and 4; except for R, their pIs, as judged from isoelectric focusing, appeared to lie in the range from pH 4 to 5.2. In the presence of 6 M urea PR 1a was split into two components, one of which was strongly retarded on gels, as were P and Q. None of the PRs was detected when gels were stained for glycoproteins.By combinations of gel filtration, DEAE-cellulose chromatography, and chromatofocusing, PRs 1a, 1b, 1c, 2 and N were purified, their amino acid compositions determined, and antisera raised against each of these components. By Western blotting, antisera against either PR 1a, 1b, or 1c reacted with each of the components of the PR 1 group, as well as with PR S. Similarly, the antisera against either PR 2 or N reacted with both 2 and N, as well as with O and R. On the basis of major similarities in molecular weight characteristics, amino acid compositions, and serological relationships, it is proposed to classify tobacco PRs into five groups: 1: PRs 1a, 1b, and 1c; 2: 2a (formerly 2), 2b (N), and 2c (O); 3: 3a (P), and 3b (Q); 4: 4a and 4b (the two components of R); and 5: PR 5 (S). 相似文献
55.
C. Gebhardt E. Ritter A. Barone T. Debener B. Walkemeier U. Schachtschabel H. Kaufmann R. D. Thompson M. W. Bonierbale M. W. Ganal S. D. Tanksley F. Salamini 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1991,83(1):49-57
Summary An RFLP linkage map of the potato is presented which comprises 304 loci derived from 230 DNA probes and one morphological marker (tuber skin color). The self-incompatibility locus of potato was mapped to chromosome I, which is homoeologous to tomato chromosome I. By mapping chromosome-specific tomato RFLP markers in potato and, vice versa, potato markers in tomato, the different potato and tomato RFLP maps were aligned to each other and the similarity of the potato and tomato genome was confirmed. The numbers given to the 12 potato chromosomes are now in accordance with the established tomato nomenclature. Comparisons between potato RFLP maps derived from different genetic backgrounds revealed conservation of marker order but differences in chromosome and total map length. In particular, significant reduction of map length was observed in interspecific compared to intraspecific crosses. The distribution of regions with distorted segregation ratios in the genome was analyzed for four potato parents. The most prominent distortion of recombination was found to be caused by the self-incompatibility locus. 相似文献
56.
Stefan Rüttermann Taina Trellenkamp Nora Bergmann Thomas Beikler Helmut Ritter Ralf Janda 《PloS one》2013,8(11)
Purpose
To investigate the antibacterial effect and the effect on the material properties of a novel delivery system with Irgasan as active agent and methacrylated polymerizable Irgasan when added to experimental dental resin composites.Materials and Methods
A delivery system based on novel polymeric hollow beads, loaded with Irgasan and methacrylated polymerizable Irgasan as active agents were used to manufacture three commonly formulated experimental resin composites. The non-modified resin was used as standard (ST). Material A contained the delivery system providing 4 % (m/m) Irgasan, material B contained 4 % (m/m) methacrylated Irgasan and material C 8 % (m/m) methacrylated Irgasan. Flexural strength (FS), flexural modulus (FM), water sorption (WS), solubility (SL), surface roughness Ra, polymerization shrinkage, contact angle Θ, total surface free energy γS and its apolar γS LW, polar γS AB, Lewis acid γS +and base γS - term as well as bacterial viability were determined. Significance was p < 0.05.Results
The materials A to C were not unacceptably influenced by the modifications and achieved the minimum values for FS, WS and SL as requested by EN ISO 4049 and did not differ from ST what was also found for Ra. Only A had lower FM than ST. Θ of A and C was higher and γS AB of A and B was lower than of ST. Materials A to C had higher γS + than ST. The antibacterial effect of materials A to C was significantly increased when compared with ST meaning that significantly less vital cells were found.Conclusion
Dental resin composites with small quantities of a novel antibacterially doped delivery system or with an antibacterial monomer provided acceptable physical properties and good antibacterial effectiveness. The sorption material being part of the delivery system can be used as a vehicle for any other active agent. 相似文献57.
Chakraborty R Morel AS Sutton JK Appay V Ripley RM Dong T Rostron T Ogola S Palakudy T Musoke R D'Agostino A Ritter M Rowland-Jones SL 《Journal of immunology (Baltimore, Md. : 1950)》2005,174(12):8191-8199
Without treatment most HIV-1-infected children in Africa die before their third birthday (>89%) and long-term nonprogressors are rare. The mechanisms underlying nonprogression in HIV-1-infected children are not well understood. In the present study, we examined potential correlates of delayed HIV disease progression in 51 HIV-1-infected African children. Children were assigned to progression subgroups based on clinical characterization. HIV-1-specific immune responses were studied using a combination of ELISPOT assays, tetramer staining, and FACS analysis to characterize the magnitude, specificity, and functional phenotype of HIV-1-specific CD8(+) and CD4(+) T cells. Host genetic factors were examined by genotyping with sequence-specific primers. HIV-1 nef gene sequences from infecting isolates from the children were examined for potential attenuating deletions. Thymic output was measured by T cell rearrangement excision circle assays. HIV-1-specific CD8(+) T cell responses were detected in all progression groups. The most striking attribute of long-term survivor nonprogressors was the detection of HIV-1-specific CD4(+) Th responses in this group at a magnitude substantially greater than previously observed in adult long-term nonprogressors. Although long-term survivor nonprogressors had a significantly higher percentage of CD45RA(+)CD4(+) T cells, nonprogression was not associated with higher thymic output. No protective genotypes for known coreceptor polymorphisms or large sequence deletions in the nef gene associated with delayed disease progression were identified. In the absence of host genotypes and attenuating mutations in HIV-1 nef, long-term surviving children generated strong CD4(+) T cell responses to HIV-1. As HIV-1-specific helper cells support anti-HIV-1 effector responses in active disease, their presence may be important in delaying disease progression. 相似文献
58.
Pharmacological experiments suggest that satiation associated with intestinal infusion of several nutrients is mediated by CCK-A receptors. Otsuka Long-Evans Tokushima Fatty, (OLETF), rats do not express CCK-A receptors and are insensitive to the satiation-producing effects of exogenous CCK. To further evaluate the role of CCK-A receptors in satiation by intestinal nutrient infusion, we examined intake of solid (pelleted rat chow) or liquid (12.5% glucose) food intake, following intestinal infusions of fats (oleic acid or fat emulsion), sugars (maltotriose or glucose), or peptone in OLETF rats and Long Evans Tokushima Otsuka control rats (LETO). Intestinal infusion of glucose or maltotriose reduced solid food intake more in LETO than in OLETF rats from 30 min through 4 h post infusion. Reduction of solid food intake by intestinal infusions of fat or peptone did not differ between OLETF and LETO rats during the first 30 min post infusion, but reduction of intake by these infusates was attenuated in OLETF rats over the ensuing 4h post infusion. Intestinal infusion of glucose, oleate, fat emulsion and peptone reduced 30-min intake of 12.5% glucose more in LETO than OLETF rats. Furthermore, pretreatment with the CCK-A receptor antagonist, devazepide, attenuated intestinal nutrient-induced reduction of food intake only in LETO, but not OLETF rats. Our results confirm pharmacological results, indicating that CCK-A receptors participate in satiation by nutrients that elevate plasma CCK concentrations, as well as by nutrients that do not stimulate secretion of endocrine CCK. In addition, our results indicate: 1) that OLETF rats have deficits in the satiation response to a variety of intestinal nutrient infusions; 2) that the temporal pattern for CCK-A receptor participation in satiation by intestinal nutrients is different during ingestion of liquid and solid foods and 3) that intestinal nutrients provide some satiation signals that are CCK-A receptor mediated and some that are not. 相似文献
59.
A full saturated linkage map of<Emphasis Type="Italic"> Picea abies</Emphasis> including AFLP,SSR, ESTP, 5S rDNA and morphological markers 总被引:3,自引:0,他引:3
Acheré V Faivre-Rampant P Jeandroz S Besnard G Markussen T Aragones A Fladung M Ritter E Favre JM 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2004,108(8):1602-1613
Based on an F1 progeny of 73 individuals, two parental maps were constructed according to the double pseudo-test cross strategy. The paternal map contained 16 linkage groups for a total genetic length of 1,792 cM. The maternal map covered 1,920 cM, and consisted of 12 linkage groups. These parental maps were then integrated using 66 intercross markers. The resulting consensus map covered 2,035 cM and included 755 markers (661 AFLPs, 74 SSRs, 18 ESTPs, the 5S rDNA and the early cone formation trait) on 12 linkage groups, reflecting the haploid number of chromosomes of Picea abies. The average spacing between two adjacent markers was 2.6 cM. The presence of 39 of the SSR and/or ESTP markers from this consensus map on other published maps of different Picea and Pinus species allowed us to establish partial linkage group homologies across three P. abies maps (up to five common markers per linkage group). This first saturated linkage map of P. abies could be therefore used as a support for developing comparative genome mapping in conifers.Communicated by O. Savolainen 相似文献
60.
Dagmar Waberski Anke Döhring Florencia Ardón Nadine Ritter Holm Zerbe Hans-Joachim Schuberth Marion Hewicker-Trautwein Karl Fritz Weitze Ronald HF Hunter 《Acta veterinaria Scandinavica》2006,48(1):13-8
Whole boar semen or seminal plasma has been demonstrated to advance the time of ovulation in gilts. As a means of clarifying
this influence, the contribution of uterine lymphatics and their white cell populations has been examined. After duct visualisation
with Evan's blue, lymph was sampled from a mesometrial vessel in eight pre-ovulatory gilts whose uterine lumen was infused
simultaneously with whole semen in one ligated horn and saline in the contralateral ligated horn. Lymph was collected from
cannulated vessels for periods of up to four hours under general anaesthesia. Thereafter, mesometrial lymph nodes, utero-tubal
junction and uterine wall tissues were sampled. The proportion of nucleated cells in the sampled lymph increased towards the
end of the collection period, but erythrocytes were found in all instances preventing a meaningful differentiation and identification
of leukocytes. Prominent uterine lymph nodes were present in the mesometrium on both sides of the reproductive tract in 7
of 10 gilts. Differences in cellular contents were demonstrated between the side of the tract infused with semen and that
infused with saline control. Two of 4 gilts had lower values for CD4 (Cluster Differentiation) and 3 of 6 gilts higher values
for MHC II (Major Histocompatibility Complex) markers on the side challenged with semen. In contrast, values remained constant
for CD8 but ranged widely for CD18. Immunohistochemical analysis of uterine tissue samples for MHC II+ cells revealed significant
differences (P < 0.05) between the control and semen-treated ligated portions of the horns, as well as between the tissue
sample of uterine wall and that from the utero-tubal junction, but there were no significant differences for CD4+ cells. It
therefore remains plausible that semen-induced cytokines in the uterine lymph undergo counter-current transfer to the ipsilateral
ovary and accelerate the final maturation of pre-ovulatory Graafian follicles. 相似文献