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971.
972.
X Gu 《Journal of computational biology》2001,8(3):221-234
In this paper, I present a statistical framework for modeling the functional divergence after gene duplication. A rate-component model to describe the rate covariation among homologous genes of a gene family is implemented when a phylogenetic tree is known. The Markov chain model is rigorous but may require a huge amount of computational time when the number of sequences is large. On the other hand, the Poisson-based model is mathematically analytical so that computation is very fast even for a large dataset. Moreover, under the posterior framework, we have developed a site-specific profile for predicting important amino acid residues responsible for these functional differences between member genes of a gene family. Our study may have great potential for functional genomics because it is cost-effective, and these predictions can be further tested by biological experimentation. 相似文献
973.
Crystal structure of the TLR1-TLR2 heterodimer induced by binding of a tri-acylated lipopeptide 总被引:9,自引:0,他引:9
TLR2 in association with TLR1 or TLR6 plays an important role in the innate immune response by recognizing microbial lipoproteins and lipopeptides. Here we present the crystal structures of the human TLR1-TLR2-lipopeptide complex and of the mouse TLR2-lipopeptide complex. Binding of the tri-acylated lipopeptide, Pam(3)CSK(4), induced the formation of an "m" shaped heterodimer of the TLR1 and TLR2 ectodomains whereas binding of the di-acylated lipopeptide, Pam(2)CSK(4), did not. The three lipid chains of Pam(3)CSK(4) mediate the heterodimerization of the receptor; the two ester-bound lipid chains are inserted into a pocket in TLR2, while the amide-bound lipid chain is inserted into a hydrophobic channel in TLR1. An extensive hydrogen-bonding network, as well as hydrophobic interactions, between TLR1 and TLR2 further stabilize the heterodimer. We propose that formation of the TLR1-TLR2 heterodimer brings the intracellular TIR domains close to each other to promote dimerization and initiate signaling. 相似文献
974.
Salvetti P Theau-Clément M Beckers JF Hurtaud J Guérin P Neto V Falières J Joly T 《Theriogenology》2007,67(6):1185-1193
For most domestic animals, the responses to superovulation treatments are not controlled as a consequence of the lack of knowledge on exogenous gonadotrophins effects on the ovarian function. The role of luteinizing hormone (LH) on the number and quality of embryos produced was evaluated on rabbit does superovulated with porcine FSH (pFSH). Parameters of embryos recovery, in vitro and in vivo embryo development rates after freezing/thawing were compared. We used three experimental groups: (1) control group without superovulation treatment, (2) "pFSH+pLH" and (3) "pFSH" groups where females were treated with pFSH, respectively, with (20%) or without (0%) porcine LH supplementation. The number of corpora lutea and the number of embryos produced were significantly higher (p<0.001) in superovulated does than in control group (27.1, 26.7 versus 11.9 corpora lutea and 20.3, 21.2 versus 9.6 embryos produced for pFSH+pLH, pFSH and control group, respectively). However, both gonadotrophins administrations (groups 2 and 3) led to defaults of ovulation when compared with untreated does. No significant difference was observed between the number and quality of the embryos produced by does treated with pFSH+pLH or with pFSH alone. Moreover, we observed no significant difference between results of in vivo and in vitro viability assays after thawing. We concluded that pFSH alone seems to be sufficient to stimulate the follicles growth and that exogenous pLH administrated has no effect on the quantity and quality of embryos. Further studies are needed to evaluate the hormonal patterns before and after the gonadotrophins injections in the rabbit species. 相似文献
975.
Chromium(III) is often claimed to have a positive effect on body composition, while the responses in researches with supplementation
of different chemical form of chromium are various and inconsistent. We have studied the effects of 6 weeks of treatment with
three different forms of chromium (300 μg/kg) as chromium chloride, chromium tripicolinate, and chromium nanocomposite (CrNano)
on growth, body composition, serum parameters, and tissue chromium in rats. The supplementataion of CrNano significantly increased
average daily gain, food efficiency, and lean body mass and decreased fat mass and body fat proportion and serum levels of
glucose, urea nitrogen, triglyceride, and insulin. Chromium contents in liver, kidney, and hind leg muscle were increased
significantly with the addition of CrNano in diet. The results indicate that chromium nanocomposite has higher efficacy on
growth and body composition compared to the traditional chromium agents. 相似文献
976.
Joo Mi Jeon Nam Young Ahn Bo Hwa Son Cha Young Kim Chang-deok Han Gun-Do Kim Sang Wan Gal Sung-Ho Lee 《Plant Cell, Tissue and Organ Culture》2007,88(2):225-232
PEG-mediated transformation was used for gene delivery and evaluation of various parameters affecting the transient expression of a gene for ß-glucuronidase (gus) in mesophyll protoplasts of Capsicum annuum. Transient expression was found to be dependent on PEG concentration and exposure time of plasmid DNA to protoplasts as well as the amount of plasmid DNA. Maximum GUS activity was obtained when protoplasts were applied to 40% concentration and molecular weight was 6,000 of PEG solution with 30 min of exposure time. Protoplasts of pepper were transformed with a vector, pCAMBIA::Ac, which contained a pCAMBIA1302 T-DNA vector carrying a maize transposable element, Ac (activator), a selection marker HPT (hygromycin phosphotransferase), and a GFP-coding region driven by the 35S promoter in the presence of PEG. Approximately 30% of the protoplasts expressed GFP. Visibly transformed colonies were obtained from protoplasts after 2 months of culture and GFP was expressed. Southern hybridization confirmed the presence of Ac in the pepper genome. 相似文献
977.
Eparvier V Thoison O Bousserouel H Guéritte F Sévenet T Litaudon M 《Phytochemistry》2007,68(5):604-608
Bioassay guided purification of the ethanolic extract of the bark of New Caledonian Pittosporum pancheri Brongn. and Gris (Pittosporaceae) led to the isolation and characterization of two new farnesyl monoglycosides, pancherins A and B. The structure of these compounds were determined on the basis of spectroscopic studies. The new compounds displayed a significant activity in the in vitro cytotoxic assay against KB cancer cell line, and pancherin A inhibits weakly farnesyl protein transferase. 相似文献
978.
Park SH Kim CM Je BI Park SH Park SJ Piao HL Xuan YH Choe MS Satoh K Kikuchi S Lee KH Cha YS Ahn BO Ji HS Yun DW Lee MC Suh SC Eun MY Han CD 《Planta》2007,227(1):1-12
OSH6 (Oryza sativa Homeobox6) is an ortholog of lg3 (Liguleless3) in maize. We generated a novel allele, termed OSH6-Ds, by inserting a defective Ds element into the third exon of OSH6, which resulted in a truncated OSH6 mRNA. The truncated mRNA was expressed ectopically in leaf tissues and encoded the N-terminal region of OSH6, which includes
the KNOX1 and partial KNOX2 subdomains. This recessive mutant showed outgrowth of bracts or produced leaves at the basal node
of the panicle. These phenotypes distinguished it from the OSH6 transgene whose ectopic expression led to a “blade to sheath transformation” phenotype at the midrib region of leaves, similar
to that seen in dominant Lg3 mutants. Expression of a similar truncated OSH6 cDNA from the 35S promoter (35S::ΔOSH6) confirmed that the ectopic expression of this product was responsible for the aberrant bract development. These data suggest
that OSH6-Ds interferes with a developmental mechanism involved in bract differentiation, especially at the basal nodes of panicles.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
979.
Gu XY Foley ME 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2007,114(4):745-754
The short-day plant rice varies greatly in photoperiod sensitivity (PS) for flowering. The hybrid F1 from a cross between the day-neutral pure line EM93-1 and the weedy rice accession SS18-2 had stronger PS than SS18-2. Some
BC1 (EM93-1/F1) segregates were even more sensitive to photoperiod than the F1, as indicated by later flowering or no flowering after 250 days under a 14-h long daylength. A genome-wide scan identified
the quantitative trait loci Se
7.1, Se
7.2 and Se
8 for PS from the BC1 population, with all alleles that inhibit flowering derived from SS18-2. These three loci regulate the time of flowering
under long daylength through their main effects, and di- and trigenic epistases. Under a 10-h short daylength, the regulation
is through Se
7.1 and Se
8 main effects and digenic epistases involving all three loci. The short daylength not only nullified the main effect of Se
7.2, but also changed its epistatic effects from inhibiting flowering under long daylength to promoting flowering. The epistases
indicate that genes underlying the three PS loci work in the same pathway for the control of flowering. Many non-flowered
BC1s were the trigenic heterozygote; this suggests that the three PS loci are also involved in genetic control of critical daylength. 相似文献
980.
Cho EJ Hwang HJ Kim SW Oh JY Baek YM Choi JW Bae SH Yun JW 《Applied microbiology and biotechnology》2007,75(6):1257-1265
The anti-diabetic activities of the exopolysaccharides (EPS) produced by submerged mycelial culture of two different mushrooms,
Tremella fuciformis and Phellinus baumii, in ob/ob mice were investigated. All the animals were randomly divided into three groups with seven animals in each group: The control
group received 0.9% NaCl solution; the diabetic groups were treated with EPS from T. fuciformis (Tf EPS) and P. baumii (Pb EPS) at the level of 200 mg/kg body weight using an oral zoned daily for 52 days. The plasma glucose levels in the EPS-fed
mice were substantially reduced by about 52% (Tf EPS) and 32% (Pb EPS), respectively, as compared to control mice. The results
of oral glucose tolerance test (OGTT) revealed that both EPS-fed groups significantly increased the glucose disposal after
52 days of EPS treatments. Furthermore, higher food efficiency ratios and reduced blood triglyceride levels were observed
in the EPS-treated groups. Because peroxisome proliferator-activated receptor gamma (PPAR-γ) is indeed a key regulator of
insulin action, we investigated the expression pattern of adipose tissue PPAR-γ messenger RNA (mRNA) and plasma levels of
PPAR-γ. It was revealed that PPAR-γ was significantly activated in response to EPS treatments. The results suggested that
both EPS exhibited considerable hypoglycemic effect and improved insulin sensitivity possibly through regulating PPAR-γ-mediated
lipid metabolism. Our results indicated that two mushroom-derived EPS might be developed as potential oral hypoglycemic agents
or functional foods for the management of non-insulin-dependent diabetes mellitus. 相似文献