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1.
Carbohydrate moiety of the Petunia inflata S3 protein is not required for self-incompatibility interactions between pollen and pistil. 总被引:7,自引:3,他引:4 下载免费PDF全文
For Petunia inflata and Nicotiana alata, which display gametophytic self-incompatibility, S proteins (the products of the multiallelic S gene in the pistil) have been shown to control the pistil's ability to recognize and reject self-pollen. The biochemical mechanism for rejection of self-pollen by S proteins has been shown to involve their ribonuclease activity; however, the molecular basis for self/non-self recognition by S proteins is not yet understood. Here, we addressed whether the glycan chain of the S3 protein of P. inflata is involved in self/non-self recognition by producing a nonglycosylated S3 protein in transgenic plants and examining the effect of deglycosylation on the ability of the S3 protein to reject S3 pollen. The S3 gene was mutagenized by replacing the codon for Asn-29, which is the only potential N-glycosylation site of the S3 protein, with a codon for Asp, and the mutant S3 gene was introduced into P. inflata plants of the S1S2 genotype. Six transgenic plants that produced a normal level of the nonglycosylated S3 protein acquired the ability to reject S3 pollen completely. These results suggest that the carbohydrate moiety of the S3 protein does not play a role in recognition or rejection of self-pollen and that the S allele specificity determinant of the S3 protein and those S proteins that contain a single glycan chain at the same site as the S3 protein must reside in the amino acid sequence itself. 相似文献
2.
Peng Ni Robert C. VaughanBrady Tragesser Haley HooverC. Cheng Kao 《Journal of molecular biology》2014
Brome mosaic virus (BMV) packages its genomic and subgenomic RNAs into three separate viral particles. BMV purified from barley, wheat, and tobacco have distinct relative abundances of the encapsidated RNAs. We seek to identify the basis for the host-dependent differences in viral RNA encapsidation. Sequencing of the viral RNAs revealed recombination events in the 3′ untranslated region of RNA1 of BMV purified from barley and wheat, but not from tobacco. However, the relative amounts of the BMV RNAs that accumulated in barley and wheat are similar and RNA accumulation is not sufficient to account for the difference in RNA encapsidation. Virions purified from barley and wheat were found to differ in their isoelectric points, resistance to proteolysis, and contacts between the capsid residues and the RNA. Mass spectrometric analyses revealed that virions from the three hosts had different post-translational modifications that should impact the physiochemical properties of the virions. Another major source of variation in RNA encapsidation was due to the purification of BMV particles to homogeneity. Highly enriched BMV present in lysates had a surprising range of sizes, buoyant densities, and distinct relative amounts of encapsidated RNAs. These results show that the encapsidated BMV RNAs reflect a combination of host effects on the physiochemical properties of the viral capsids and the enrichment of a subset of virions. The previously unexpected heterogeneity in BMV should influence the timing of the infection and also the host innate immune responses. 相似文献
3.
The selective genotyping approach, where only individuals from the high and low extremes of the trait distribution are selected for genotyping and the remaining individuals are not genotyped, has been known as a cost-saving strategy to reduce genotyping work and can still maintain nearly equivalent efficiency to complete genotyping in QTL mapping. We propose a novel and simple statistical method based on the normal mixture model for selective genotyping when both genotyped and ungenotyped individuals are fitted in the model for QTL analysis. Compared to the existing methods, the main feature of our model is that we first provide a simple way for obtaining the distribution of QTL genotypes for the ungenotyped individuals and then use it, rather than the population distribution of QTL genotypes as in the existing methods, to fit the ungenotyped individuals in model construction. Another feature is that the proposed method is developed on the basis of a multiple-QTL model and has a simple estimation procedure similar to that for complete genotyping. As a result, the proposed method has the ability to provide better QTL resolution, analyze QTL epistasis, and tackle multiple QTL problem under selective genotyping. In addition, a truncated normal mixture model based on a multiple-QTL model is developed when only the genotyped individuals are considered in the analysis, so that the two different types of models can be compared and investigated in selective genotyping. The issue in determining threshold values for selective genotyping in QTL mapping is also discussed. Simulation studies are performed to evaluate the proposed methods, compare the different models, and study the QTL mapping properties in selective genotyping. The results show that the proposed method can provide greater QTL detection power and facilitate QTL mapping for selective genotyping. Also, selective genotyping using larger genotyping proportions may provide roughly equivalent power to complete genotyping and that using smaller genotyping proportions has difficulties doing so. The R code of our proposed method is available on http://www.stat.sinica.edu.tw/chkao/. 相似文献
4.
Objective
Although recent studies have improved understanding of quality of life (QOL) outcomes of breast conserving surgery, few have used longitudinal data for more than two time points, and few have examined predictors of QOL over two years. Additionally, the longitudinal data analyses in such studies rarely apply the appropriate statistical methodology to control for censoring and inter-correlations arising from repeated measures obtained from the same patient pool. This study evaluated an internet-based system for measuring longitudinal changes in QOL and developed a cloud-based system for managing patients after breast conserving surgery.Methods
This prospective study analyzed 657 breast cancer patients treated at three tertiary academic hospitals. Related hospital personnel such as surgeons and other healthcare professionals were also interviewed to determine the requirements for an effective cloud-based system for surveying QOL in breast cancer patients. All patients completed the SF-36, Quality of Life Questionnaire (QLQ-C30) and its supplementary breast cancer measure (QLQ-BR23) at baseline, 6 months, 1 year, and 2 years postoperatively. The 95% confidence intervals for differences in responsiveness estimates were derived by bootstrap estimation. Scores derived by these instruments were interpreted by generalized estimating equation before and after surgery.Results
All breast cancer surgery patients had significantly improved QLQ-C30 and QLQ-BR23 subscale scores throughout the 2-year follow-up period (p<0.05). During the study period, QOL generally had a negative association with advanced age, high Charlson comorbidity index score, tumor stage III or IV, previous chemotherapy, and long post-operative LOS. Conversely, QOL was positively associated with previous radiotherapy and hormone therapy. Additionally, patients with high scores for preoperative QOL tended to have high scores for QLQ-C30, QLQ-BR23 and SF-36 subscales. Based on the results of usability testing, the five constructs were rated on a Likert scale from 1–7 as follows: system usefulness (5.6±1.8), ease of use (5.6±1.5), information quality (5.4±1.4), interface quality (5.5±1.4), and overall satisfaction (5.5±1.6).Conclusions
The current trend in clinical medicine is applying therapies and interventions that improve QOL. Therefore, a potentially vast amount of internet-based QOL data is available for use in defining patient populations that may benefit from therapeutic intervention. Additionally, before undergoing breast conserving surgery, patients should be advised that their postoperative QOL depends not only on the success of the surgery, but also on their preoperative functional status. 相似文献5.
Photosynthetic CO2 uptake and chlorophyll (Chl) a fluorescence of C4 perennial grasses, Miscanthus floridulus (Labill) Warb and M. transmorrisonensis Hayata, from altitudes in central Taiwan
of 390 and 2700 m, respectively, were studied at 10 and 25 °C to find if the species differ in their photosynthetic responses
to a low temperature, and whether their photosystems 2 become more susceptible to the photoinhibition at low temperatures.
For both species, the maximum photosynthetic rate (Pmax) was reduced when the leaves were exposed to 10 °C. At irradiances higher than 400 μmol m-2 s-1, the values of Fv/Fm were reduced in both species at 10 °C but not at 25 °C, which indicated the photoinhibition at 10 °C. Reductions in Pmax and the values of Fv/Fm at 10 °C were lesser in M. transmorrisonensis than in M. floridulus.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
6.
Impaired secretion and fluid-phase endocytosis in the End4 mutant of Chinese hamster ovary cells 总被引:6,自引:0,他引:6
R H Wang P A Colbaugh C Y Kao E A Rutledge R K Draper 《The Journal of biological chemistry》1990,265(33):20179-20187
Mutant V.24.1 defines the End4 complementation group of temperature-sensitive Chinese hamster ovary cell mutants selected for resistance to protein toxins. We investigated the secretory pathway in the mutant cells and found: 1) The hemagglutinin of influenza virus failed to reach the plasma membrane and was retained in a form sensitive to endoglycosidase H at the restrictive temperature. 2) Transferrin receptors synthesized at the restrictive temperature remained sensitive to endoglycosidase H. 3) Secretion of total soluble protein into the medium was strongly reduced at high temperature. These data indicate that V.24.1 cells are defective in secretion at the restrictive temperature. To see what effect the lesion had on the endocytic pathway, we measured the accumulation and recycling of the fluid-phase marker horseradish peroxidase. Accumulation was inhibited by 50% while recycling was barely affected, suggesting that the rate of fluid-phase endocytosis was reduced. We previously showed that the clathrin-coated pit pathway of endocytosis was not affected in the mutant, indicated by a normal transferrin cycle (Colbaugh, P. A., Stookey, M., and Draper, R. K. (1989) J. Cell Biol. 108, 2211-2219). Thus, the secretory lesion correlates with reduced fluid-phase endocytosis without impairing the clathrin-dependent pathway of receptor-mediated endocytosis. We also investigated the delivery of endocytosed material to lysosomes and found that delivery was partially, but not completely, impaired in the mutant. This suggests that endocytosed material can enter lysosomes, although slowly, in the absence of a functional secretory pathway. 相似文献
7.
8.
Does the use of DM-nitrophen,nitr-5, or diazo-2 interfere with the measurement of indo-1 fluorescence? 总被引:1,自引:0,他引:1
Emission spectra of the photolabile Ca2+ chelators DM-nitrophen, nitr-5, and diazo-2 were studied alone, and in the presence of indo-1, to investigate potential interactions that would make the simultaneous manipulation and ratiometric measurement of the intracellular Ca2+ concentration difficult. Neither diazo-2 nor its photoproduct were found to be significantly fluorescent, and consequently concentrations of diazo-2 up to 20 times that of indo-1 did not distort the emission spectra of indo-1. DM-nitrophen was scarcely fluorescent, but its fluorescence did increase upon photolysis. In contrast to diazo-2 and DM-nitrophen, nitr-5 itself was found to be quite fluorescent, and this fluorescence was significantly increased upon photolysis. Thus, combined use of nitr-5 and indo-1 poses the most difficulty. The emission spectra of all the investigated compounds were used to define experimental conditions and calibration procedures that make possible simultaneous measurement and manipulation of the intracellular Ca2+ concentration. 相似文献
9.
The effects of salicylic acid (SA) on ethylene biosynthesis in detached rice leaves were investigated. SA at pH 3.5 effectively inhibited ethylene production within 2 h of its application. It inhibited the conversion of ACC to ethylene, but did not affect the levels of ACC and conjugated ACC. Thus, the inhibitory effect of SA resulted from the inhibition of both synthesis of ACC and the conversion of ACC to ethylene.Abbreviations ACC
1-aminocyclopropane-1-carboxylic acid
- EFE
ethylene-forming enzyme
- SA
salicylic acid 相似文献
10.