全文获取类型
收费全文 | 449篇 |
免费 | 38篇 |
出版年
2024年 | 1篇 |
2022年 | 5篇 |
2021年 | 6篇 |
2020年 | 1篇 |
2019年 | 3篇 |
2018年 | 5篇 |
2017年 | 10篇 |
2016年 | 11篇 |
2015年 | 21篇 |
2014年 | 28篇 |
2013年 | 33篇 |
2012年 | 41篇 |
2011年 | 23篇 |
2010年 | 14篇 |
2009年 | 21篇 |
2008年 | 16篇 |
2007年 | 22篇 |
2006年 | 24篇 |
2005年 | 20篇 |
2004年 | 11篇 |
2003年 | 20篇 |
2002年 | 16篇 |
2001年 | 21篇 |
2000年 | 17篇 |
1999年 | 13篇 |
1998年 | 16篇 |
1997年 | 6篇 |
1996年 | 6篇 |
1995年 | 6篇 |
1994年 | 5篇 |
1993年 | 6篇 |
1992年 | 5篇 |
1990年 | 3篇 |
1989年 | 9篇 |
1988年 | 1篇 |
1987年 | 4篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1976年 | 2篇 |
1973年 | 1篇 |
1971年 | 1篇 |
1967年 | 1篇 |
排序方式: 共有487条查询结果,搜索用时 15 毫秒
131.
132.
Weijers M Barneveld PA Cohen Stuart MA Visschers RW 《Protein science : a publication of the Protein Society》2003,12(12):2693-2703
The heat-induced denaturation kinetics of two different sources of ovalbumin at pH 7 was studied by chromatography and differential scanning calorimetry. The kinetics was found to be independent of protein concentration and salt concentration, but was strongly dependent on temperature. For highly pure ovalbumin, the decrease in nondenatured native protein showed first-order dependence. The activation energy obtained with different techniques varied between 430 and 490 kJ*mole(-1). First-order behavior was studied in detail using differential scanning calorimetry. The calorimetric traces were irreversible and highly scan rate-dependent. The shape of the thermograms as well as the scan rate dependence can be explained by assuming that the thermal denaturation takes place according to a simplified kinetic process where N is the native state, D is denatured (or another final state) and k a first-order kinetic constant that changes with temperature, according to the Arrhenius equation. A kinetic model for the temperature-induced denaturation and aggregation of ovalbumin is presented. Commercially obtained ovalbumin was found to contain an intermediate-stable fraction (IS) of about 20% that was unable to form aggregates. The denaturation of this fraction did not satisfy first-order kinetics. 相似文献
133.
Aerts J Crooijmans R Cornelissen S Hemmatian K Veenendaal T Jaadar A van der Poel J Fillon V Vignal A Groenen M 《Cytogenetic and genome research》2003,102(1-4):297-303
Different genomic resources in chicken were integrated through the Wageningen chicken BAC library. First, a BAC anchor map was created by screening this library with two sets of markers: microsatellite markers from the consensus linkage map and markers created from BAC end sequencing in chromosome walking experiments. Second, HINdIII digestion fingerprints were created for all BACs of the Wageningen chicken BAC library. Third, cytogenetic positions of BACs were assigned by FISH. These integrated resources will facilitate further chromosome-walking experiments and whole-genome sequencing. 相似文献
134.
Jungerius BJ Veenendaal A Van Oost BA Te Pas MF Groenen MA 《Molecular biotechnology》2003,25(3):283-288
Single-nucleotide polymorphisms (SNPs) are increasingly used as genetic markers. Although a high number of SNP-genotyping techniques have been described, most techniques still have low throughput or require major investments. For laboratories that have access to an automated sequencer, a single-base extension (SBE) assay can be implemented using the ABI SNaPshot trade mark kit. Here we present a modified protocol comprising multiplex template generation, multiplex SBE reaction, and multiplex sample analysis on a gel-based sequencer such as the ABI 377. These sequencers run on a Macintosh platform, but on this platform the software available for analysis of data from the ABI 377 has limitations. First, analysis of the size standard included with the kit is not facilitated. Therefore a new size standard was designed. Second, using Genotyper (ABI), the analysis of the data is very tedious and time consuming. To enable automated batch analysis of 96 samples, with 10 SNPs each, we developed SNPtyper. This is a spreadsheet-based tool that uses the data from Genotyper and offers the user a convenient interface to set parameters required for correct allele calling. In conclusion, the method described will enable any lab having access to an ABI sequencer to genotype up to 1000 SNPs per day for a single experimenter, without investing in new equipment. 相似文献
135.
Principles of quantitation of viral loads using nucleic acid sequence-based amplification in combination with homogeneous detection using molecular beacons 总被引:3,自引:1,他引:2
下载免费PDF全文
![点击此处可从《Nucleic acids research》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Weusten JJ Carpay WM Oosterlaken TA van Zuijlen MC van de Wiel PA 《Nucleic acids research》2002,30(6):e26
For quantitative NASBA-based viral load assays using homogeneous detection with molecular beacons, such as the NucliSens EasyQ HIV-1 assay, a quantitation algorithm is required. During the amplification process there is a constant growth in the concentration of amplicons to which the beacon can bind while generating a fluorescence signal. The overall fluorescence curve contains kinetic information on both amplicon formation and beacon binding, but only the former is relevant for quantitation. In the current paper, mathematical modeling of the relevant processes is used to develop an equation describing the fluorescence curve as a function of the amplification time and the relevant kinetic parameters. This equation allows reconstruction of RNA formation, which is characterized by an exponential increase in concentrations as long as the primer concentrations are not rate limiting and by linear growth over time after the primer pool is depleted. During the linear growth phase, the actual quantitation is based on assessing the amplicon formation rate from the viral RNA relative to that from a fixed amount of calibrator RNA. The quantitation procedure has been successfully applied in the NucliSens EasyQ HIV-1 assay. 相似文献
136.
Orofacial clefts and spina bifida: N-acetyltransferase phenotype,maternal smoking,and medication use
van Rooij IA Groenen PM van Drongelen M Te Morsche RH Peters WH Steegers-Theunissen RP 《Teratology》2002,66(5):260-266
BACKGROUND: Orofacial clefts and spina bifida are midline defects with a multifactorial etiology. Maternal smoking and medication use periconceptionally have been studied as risk factors for these malformations. The biotransformation enzyme N-acetyltransferase 2 (NAT2), plays a part in the inactivation of toxic compounds in cigarette smoke and medication. We investigated maternal NAT2 phenotype and the interaction with smoking and medication use periconceptionally on orofacial cleft and spina bifida risk in offspring. METHODS: In this case-control study of 45 mothers of orofacial cleft children, 39 mothers of spina bifida children and 73 control mothers, NAT2 acetylator status was determined by measuring urinary caffeine metabolites. RESULTS: Slow NAT2 acetylators showed no increased risk for orofacial cleft (OR = 1.0, 95% CI: 0.4-2.3) or spina bifida offspring (OR = 0.7, 95% CI: 0.3-1.7) compared to fast NAT2 acetylators. More mothers with orofacial cleft and spina bifida offspring smoked cigarettes (36% and 23% respectively) and used medication periconceptionally (38% and 44% respectively) compared to control mothers (smoking:18%, medication use:19%). No interaction between maternal NAT2 acetylator status and smoking or medication use was observed for orofacial cleft and spina bifida risk. CONCLUSIONS: Maternal smoking and medication use is associated with orofacial cleft risk as well as medication use is with spina bifida. The maternal NAT2 acetylator status, however, was not associated with an increased risk for orofacial cleft or spina bifida offspring, nor in combination with periconceptional smoking or medication use. 相似文献
137.
138.
Catimel B; Scott AM; Lee FT; Hanai N; Ritter G; Welt S; Old LJ; Burgess AW; Nice EC 《Glycobiology》1998,8(9):927-938
We describe a novel immobilization technique to investigate interactions
between immobilized gangliosides (GD3, GM1, and GM2) and their respective
antibodies, antibody fragments, or binding partners using an optical
biosensor. Immobilization was performed by direct injection onto a
carboxymethyldextran sensor chip and did not require derivatization of the
sensor surface or the ganglioside. The ganglioside appeared to bind to the
sensor surface by hydrophobic interaction, leaving the carbohydrate epitope
available for antibody or, in the case of GM1, cholera toxin binding. The
carboxyl group of the dextran chains on the sensor surface did not appear
to be involved in the immobilization as evidenced by equivalent levels of
immobilization following conversion of the carboxyl groups into acyl amino
esters, but rather the dextran layer provided a hydrophilic coverage of the
sensor chip which was essential to prevent nonspecific binding. This
technique gave better reactivity and specificity for anti- ganglioside
monoclonal antibodies (anti-GD3: KM871, KM641, R24; and anti-GM2: KM966)
than immobilization by hydrophobic interaction onto a gold sensor surface
or photoactivated cross-linking onto carboxymethydextran. This rapid
immobilization procedure has facilitated detailed kinetic analysis of
ganglioside/antibody interactions, with the surface remaining viable for a
large number of cycles (>125). Kinetic constants were determined from
the biosensor data using linear regression, nonlinear least squares and
equilibrium analysis. The values of kd, ka, and KAobtained by nonlinear
analysis (KAKM871 = 1.05, KM641 = 1.66, R24 = 0.14, and KM966 = 0.65 x
10(7) M- 1) were essentially independent of concentration and showed good
agreement with data obtained by other analytical methods.
相似文献
139.
Highly polymorphic microsatellite markers in poultry 总被引:1,自引:0,他引:1
R. P. M. A. Crooijmans A. J. A.van Kampen J. J.van der Poel MAM Groenen 《Animal genetics》1993,24(6):441-443
Microsatellite markers have been established for a large number of species, but up till now very few polymorphic microsatellite markers have been reported in poultry. We have isolated 34 polymorphic chicken microsatellite markers of the poly (TG) type. The number of repeats varied from 9 up to 33. Often, other repeats such as poly (T) or poly (GAA) were present adjacent to the poly (TG) repeat. Polymerase chain reaction amplification of the microsatellites resulted in detection of three or more alleles in a test panel of five different animals for 75% of the microsatellites. Segregation of five microsatellite markers has been tested in a small family. 相似文献
140.
Influence of a natural and a synthetic inhibitor of factor XIIIa on fibrin clot rheology 总被引:2,自引:0,他引:2
下载免费PDF全文
![点击此处可从《Biophysical journal》网站下载免费的PDF全文](/ch/ext_images/free.gif)
We investigated the origins of greater clot rigidity associated with FXIIIa-dependent cross-linking. Fibrin clots were examined in which cross-linking was controlled through the use of two inhibitors: a highly specific active-center-directed synthetic inhibitor of FXIIIa, 1,3-dimethyl-4,5-diphenyl-2[2(oxopropyl)thio]imidazolium trifluoromethylsulfonate, and a patient-derived immunoglobulin directed mainly against the thrombin-activated catalytic A subunits of thrombin-activated FXIII. Cross-linked fibrin chains were identified and quantified by one- and two-dimensional gel electrophoresis and immunostaining with antibodies specific for the alpha- and gamma-chains of fibrin. Gamma-dimers, gamma-multimers, alpha(n)-polymers, and alpha(p)gamma(q)-hybrids were detected. The synthetic inhibitor was highly effective in preventing the production of all cross-linked species. In contrast, the autoimmune antibody of the patient caused primarily an inhibition of alpha-chain cross-linking. Clot rigidities (storage moduli, G') were measured with a cone and plate rheometer and correlated with the distributions of the various cross-linked species found in the clots. Our findings indicate that the FXIIIa-induced dimeric cross-linking of gamma-chains by itself is not sufficient to stiffen the fibrin networks. Instead, the augmentation of clot rigidity was more strongly correlated with the formation of gamma-multimers, alpha(n)-polymers, and alpha(p)gamma(q)-hybrid cross-links. A mechanism is proposed to explain how these cross-linked species may enhance clot rigidity. 相似文献