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211.
A basic premise of conservation geneticists is that low levels of genetic variation are associated with fitness costs in terms
of reduced survival and fecundity. These fitness costs may frequently vary with environmental factors and should increase
under more stressful conditions. However, there is no consensus on how fitness costs associated with low genetic variation
change under natural conditions in relation to the stressfulness of the environment. On the Swedish west coast, natterjack
toad Bufo calamita populations show a strong population genetic structure and large variation in the amount of within-population genetic variation.
We experimentally examined the survival of natterjack larvae from six populations with different genetic variation in three
thermal environments corresponding to (a) the mean temperature of natural ponds (stable, laboratory), (b) a high temperature
environment occurring in desiccating ponds (stable, laboratory) and (c) an outdoor treatment mimicking the natural, variable
thermal conditions (fluctuating, semi-natural). We found that larvae in the outdoor treatment had poorer survival than larvae
in the stable environments suggesting that the outdoor treatment was more stressful. Overall, populations with higher genetic
variation had higher larval survival. However, a significant interaction between treatments and genetic variation indicated
that fitness costs associated with low genetic variation were less severe in the outdoor treatment. Thus, we found no support
for the hypothesis that fitness costs associated with low genetic variation increase under more stressful conditions. Our
results suggest that natural thermal stress may mask fitness losses associated with low genetic variation in these populations. 相似文献
212.
Vicky P. K. H. Nguyen George Hanna Natalie Rodrigues Katerina Pizzuto Eric Yang Paul Van Slyke Harold Kim Stephen H. Chen Daniel J. Dumont 《Proteomics》2010,10(8):1658-1672
Differential protein profiling by 2‐D PAGE is generally useful in biomarker discovery, proteome analysis and routine sample preparation prior to analysis by MS. The goal of this study was to compare 2‐D PAGE‐resolved protein profile of lymphatic endothelial cells to those of venous, and arterial endothelial cells isolated from lymphatic and blood vessels of bovine mesentery (bm). Three 2‐D PAGE electrophoretograms were produced for each of the three cell types and quantitatively analyzed. Protein identification by LC‐MS/MS was performed to identify 39 proteins found to be present at statistically significantly different levels in the three cell types (p<0.05). Most of the 39 proteins have not been previously reported in EC proteomic studies of 2‐D PAGE electrophoretograms. Three proteins, HSPA1B (HSP70 family member), HSPB1 (HSP27 family member), and UBE2D3 (a member of E2 ubiquitin‐conjugating enzymes) found to be at highest levels in bm arterial endothelial cells, bm venous endothelial cells, and bm lymphatic endothelial cells, respectively, were validated by immunoblotting with appropriate antibodies. The lack of substantial overlap between our results and those of other groups' comparative studies are discussed. Functional implications of differences in levels of various proteins identified in the three cell types are also discussed. 相似文献
213.
Recently, Eskola and Geritz (Bull. Math. Biol. 69:329–346, 2007) showed that several discrete-time population models can be derived mechanistically within a single ecological framework
by varying the within-season patterns of reproduction and inter-individual aggression. However, these models do not have the
Allee effect. In this paper, we modify the original modelling framework by adding different mate finding processes, and thus
derive mechanistically several population models with the Allee effect. 相似文献
214.
Leana Doherty Adrianna Vlachos Valerie Choesmel Marie-Françoise O'Donohue Catherine Clinton Colin A. Sieff Peter E. Newburger Edyta Niewiadomska Bertil Glader Jason E. Farrar Jeffrey M. Lipton Pierre-Emmanuel Gleizes Hanna T. Gazda 《American journal of human genetics》2010,86(2):222-6951
Diamond-Blackfan anemia (DBA), an inherited bone marrow failure syndrome characterized by anemia that usually presents before the first birthday or in early childhood, is associated with birth defects and an increased risk of cancer. Although anemia is the most prominent feature of DBA, the disease is also characterized by growth retardation and congenital malformations, in particular craniofacial, upper limb, heart, and urinary system defects that are present in ∼30%–50% of patients. DBA has been associated with mutations in seven ribosomal protein (RP) genes, RPS19, RPS24, RPS17, RPL35A, RPL5, RPL11, and RPS7, in about 43% of patients. To continue our large-scale screen of RP genes in a DBA population, we sequenced 35 ribosomal protein genes, RPL15, RPL24, RPL29, RPL32, RPL34, RPL9, RPL37, RPS14, RPS23, RPL10A, RPS10, RPS12, RPS18, RPL30, RPS20, RPL12, RPL7A, RPS6, RPL27A, RPLP2, RPS25, RPS3, RPL41, RPL6, RPLP0, RPS26, RPL21, RPL36AL, RPS29, RPL4, RPLP1, RPL13, RPS15A, RPS2, and RPL38, in our DBA patient cohort of 117 probands. We identified three distinct mutations of RPS10 in five probands and nine distinct mutations of RPS26 in 12 probands. Pre-rRNA analysis in lymphoblastoid cells from patients bearing mutations in RPS10 and RPS26 showed elevated levels of 18S-E pre-rRNA. This accumulation is consistent with the phenotype observed in HeLa cells after knockdown of RPS10 or RPS26 expression with siRNAs, which indicates that mutations in the RPS10 and RPS26 genes in DBA patients affect the function of the proteins in rRNA processing. 相似文献
215.
Sandra Andorf Joachim Selbig Thomas Altmann Kathrin Poos Hanna Witucka-Wall Dirk Repsilber 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2010,120(2):249-259
Heterosis is a well-known phenomenon but the underlying molecular mechanisms are not yet established. To contribute to the
understanding of heterosis at the molecular level, we analyzed genome-wide gene expression profile data of Arabidopsis thaliana in a systems biological approach. We used partial correlations to estimate the global interaction structure of regulatory
networks. Our hypothesis states that heterosis comes with an increased number of partial correlations which we interpret as
increased numbers of regulatory interactions leading to enlarged adaptability of the hybrids. This hypothesis is true for
mid-parent heterosis for our dataset of gene expression in two homozygous parental lines and their reciprocal crosses. For
the case of best-parent heterosis just one hybrid is significant regarding our hypothesis based on a resampling analysis.
Summarizing, both metabolome and gene expression level of our illustrative dataset support our proposal of a systems biological
approach towards a molecular basis of heterosis. 相似文献
216.
p27 phosphorylation by Src regulates inhibition of cyclin E-Cdk2 总被引:7,自引:0,他引:7
Chu I Sun J Arnaout A Kahn H Hanna W Narod S Sun P Tan CK Hengst L Slingerland J 《Cell》2007,128(2):281-294
The kinase inhibitor p27Kip1 regulates the G1 cell cycle phase. Here, we present data indicating that the oncogenic kinase Src regulates p27 stability through phosphorylation of p27 at tyrosine 74 and tyrosine 88. Src inhibitors increase cellular p27 stability, and Src overexpression accelerates p27 proteolysis. Src-phosphorylated p27 is shown to inhibit cyclin E-Cdk2 poorly in vitro, and Src transfection reduces p27-cyclin E-Cdk2 complexes. Our data indicate that phosphorylation by Src impairs the Cdk2 inhibitory action of p27 and reduces its steady-state binding to cyclin E-Cdk2 to facilitate cyclin E-Cdk2-dependent p27 proteolysis. Furthermore, we find that Src-activated breast cancer lines show reduced p27 and observe a correlation between Src activation and reduced nuclear p27 in 482 primary human breast cancers. Importantly, we report that in tamoxifen-resistant breast cancer cell lines, Src inhibition can increase p27 levels and restore tamoxifen sensitivity. These data provide a new rationale for Src inhibitors in cancer therapy. 相似文献
217.
We present a derivation of various discrete-time population models within a single unifying mechanistic context. By systematically varying the within-year patterns of reproduction and aggression between individuals we can derive various discrete-time population models. These models include classical examples such as the Ricker model, the Beverton-Holt model, the Skellam model, the Hassell model, and others. Some of these models until now lacked a good mechanistic interpretation or have been derived in a different context. By using this mechanistic approach, the model parameters can be interpreted in terms of individual behavior. 相似文献
218.
219.
Manuzon MY Hanna SE Luo H Yu Z Harper WJ Wang HH 《Applied and environmental microbiology》2007,73(5):1676-1677
A TaqMan real-time PCR assay was developed to quantify the tetS gene pool present in retail cheeses. This protocol offers a rapid, specific, sensitive, and culture-independent method for assessing antibiotic resistance genes in food samples rich in fats and proteins. 相似文献
220.
Wultańska D Obuch-Woszczatyński P Pituch H Luczak M 《Medycyna do?wiadczalna i mikrobiologia》2007,59(2):161-168
This study was performed to determine the susceptibility of 50 C. difficile strains isolated from faecal samples of children suspected to antibiotic associated diarrhea (AAD) to antimicrobial agents: metronidazole, vancomycin, erythromycin, clindamycin, ciprofloxacin, moxifloksacin, gatifloksacin and imipenem. The all C. difficile strains were sensitived to metronidazole and vancomycin. Twenty six per cent of strains were resistant to erythromycin and clindamycin (MLS(B) type resistance). Resitance to ciprofloxacin, moxifloxacin, gatifloxacin and imipenem was detected in 98%, 8%, 8% and 30% of C. difficile strains, respectively. 相似文献