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891.
MARIA DA LUZ MATHIAS ANTONIO MIRA 《Biological journal of the Linnean Society. Linnean Society of London》1992,46(1-2):13-24
The skulls and skins of adult house mice from the Madeira Islands have been studied and compared with those from the Salvage Islands and with material from the neighbouring Portuguese mainland man-associated and wild forms, respectively Mus musclus domesticus Rutty, 1772 and M. sprelus Lataste, 1883. Differences between island and mainland populations were found in some of the analysed features. Insular skins of mice were found to be smaller than those of specimens from the mainland. However, in Madeiran and Salvage mice the toothrows were much more developed than in the mainland house mice. It is considered that the causes of these differences lie in the different characteristics of the habitats, mainly food availability, and also in the isolation of populations. Mus musculus domesticus appears to be the only form of the house mouse to have so far successfully colonized the Madeiras. 相似文献
892.
目的:探讨"应力-生长(改建)"在细胞水平上的体现,为功能矫形治疗和矫治效果的保持提供新思路和实验依据。方法:本实验选用20只4周龄,雄性SD大鼠随机分为8组。其中实验组大鼠经戊巴比妥麻醉后佩戴上颌斜面导板,对照组未佩用。依据时间不同又分为四组:1d,7d,14d,21d。采用RT-PCR技术分析各组大鼠翼外肌组织中肌分化相关基因MyoD、myogenin mRNA的表达变化。结果:未施加功能矫形力的大鼠翼外肌组织MyoD表达伴随其生长发育呈现递减趋势,实验组在第7 d出现表达上调。同时,力学刺激后实验组动物myogenin的表达与对照组相比较在14 d组出现明显上调。结论:功能矫形力作用于翼外肌组织可以诱导MyoD和myogenin的表达上调进而诱导成肌细胞的分化。 相似文献
893.
Christopher J Jackson John E Norman Murray N Schnare Michael W Gray Patrick J Keeling Ross F Waller 《BMC biology》2007,5(1):41
Background
Dinoflagellates comprise an ecologically significant and diverse eukaryotic phylum that is sister to the phylum containing apicomplexan endoparasites. The mitochondrial genome of apicomplexans is uniquely reduced in gene content and size, encoding only three proteins and two ribosomal RNAs (rRNAs) within a highly compacted 6 kb DNA. Dinoflagellate mitochondrial genomes have been comparatively poorly studied: limited available data suggest some similarities with apicomplexan mitochondrial genomes but an even more radical type of genomic organization. Here, we investigate structure, content and expression of dinoflagellate mitochondrial genomes. 相似文献894.
Mark A. Canfield Tunu A. Ramadhani Gary M. Shaw Suzan L. Carmichael D. Kim Waller Bridget S. Mosley Marjorie H. Royle Richard S. Olney 《Birth defects research. Part A, Clinical and molecular teratology》2009,85(7):637-646
BACKGROUND : We used data from the multisite National Birth Defects Prevention Study for expected delivery dates from October 1997 through 2003, to determine whether the increased risk in anencephaly and spina bifida (neural tube defects (NTDs)) in Hispanics was explained by selected sociodemographic, acculturation, and other maternal characteristics. METHODS : For each type of defect, we examined the association with selected maternal characteristics stratified by race/ethnicity and the association with Hispanic parents' acculturation level, relative to non‐Hispanic whites. We used logistic regression and calculated crude odds ratios (ORs) and their 95% confidence intervals (CIs). RESULTS : Hispanic mothers who reported the highest level of income were 80% less likely to deliver babies with spina bifida. In addition, highly educated Hispanic and white mothers had 76 and 35% lower risk, respectively. Other factors showing differing effects for spina bifida in Hispanics included maternal age, parity, and gestational diabetes. For spina bifida there was no significant elevated risk for U.S.–born Hispanics, relative to whites, but for anencephaly, corresponding ORs ranged from 1.9 to 2.3. The highest risk for spina bifida was observed for recent Hispanic immigrant parents from Mexico or Central America residing in the United States <5 years (OR = 3.28, 95% CI = 1.46–7.37). CONCLUSIONS : Less acculturated Hispanic parents seemed to be at highest risk of NTDs. For anencephaly, U.S.–born and English‐speaking Hispanic parents were also at increased risk. Finally, from an etiologic standpoint, spina bifida and anencephaly appeared to be etiologically heterogeneous from these analyses. Birth Defects Research (Part A), 2009. © 2009 Wiley‐Liss, Inc. 相似文献
895.
【背景】芳樟醇具有特殊的香气和多种生物学活性,是食品、医药和化妆品行业的重要原料。随着合成生物学的高速发展,代谢改造微生物进行芳樟醇生物合成是当前研究的一大热点。然而在微生物的生物合成中,芳樟醇对底盘细胞的毒性是一大瓶颈问题,也是其他单萜物质生物合成的共性问题。【目的】建立合理的耐受性改造方法,以提高微生物宿主细胞对芳樟醇的耐受性。【方法】以酿酒酵母BY4741为研究对象,通过对ABC转运蛋白、活性氧调控相关酶及转录调控因子的过表达,考察它们对酿酒酵母芳樟醇耐受性的影响,并通过对酿酒酵母细胞进行定向驯化,筛选耐受性提高的酿酒酵母突变株。【结果】单独过表达ABC转运蛋白(Yor1、Snq2、Pdr5、Pdr15和Pdr18)、ROS调控相关酶(Gre2、Ctt1、Yhb1、Gpx2、Trr1、Trx2和Gsh2)及转录调控因子(Ino2、Yap1、Yap5和Stb5)并不能有效提高酿酒酵母的耐受性,但在传代适应性驯化过程中获得了两株耐受性提高的酿酒酵母突变株,将芳樟醇的致死浓度从430mg/L提高到了645mg/L以上。进一步通过基因组重测序分析揭示了驯化菌株突变位点。其中YBR074W... 相似文献
896.
897.
Morphological and functional aspects of volatile-producing glands in bees (Hymenoptera: Apidae) 总被引:1,自引:0,他引:1
CARMINDA DA CRUZ-LANDIM FÁBIO CAMARGO ABDALLA LUCIANA FIORETTI GRACIOLI-VITTI 《Insect Science》2005,12(6):467-480
Abstract In this paper we focus on the occurrence and morphological aspects of exocrine glands in several bee species. Morphology of head labial, mandibular, Dufour, and abdominal tegumentar glands was investigated under light microscopy, scanning electron microscopy and transmission electron microscopy. Most of such glands present cells with cytoplasm homogeneous and acidophilic, or contain small apparently empty vacuoles. The cytoplasm cells' ultrastructure showed a well developed smooth endoplasmic reticulum, many polymorphic mitochondria, rare Golgi, lipid droplets, myelin figures, and many basal and apical plasma membrane infoldings. All these results are discussed in the text. 相似文献
898.
Marianna Martella Flavia Pichiorri Rupesh V Chikhale Mahmoud A S Abdelhamid Zoë A E Waller Steven
S Smith 《Nucleic acids research》2022,50(6):3445
Concatemers of d(TCCC) that were first detected through their association with deletions at the RACK7 locus, are widespread throughout the human genome. Circular dichroism spectra show that d(GGGA)n sequences form G-quadruplexes when n > 3, while i-motif structures form at d(TCCC)n sequences at neutral pH when n ≥ 7 in vitro. In the PC3 cell line, deletions are observed only when the d(TCCC)n variant is long enough to form significant levels of unresolved i-motif structure at neutral pH. The presence of an unresolved i-motif at a representative d(TCCC)n element at RACK7 was suggested by experiments showing that that the region containing the d(TCCC)9 element was susceptible to bisulfite attack in native DNA and that d(TCCC)9 oligo formed an i-motif structure at neutral pH. This in turn suggested that that the i-motif present at this site in native DNA must be susceptible to bisulfite mediated deamination even though it is a closed structure. Bisulfite deamination of the i-motif structure in the model oligodeoxynucleotide was confirmed using mass spectrometry analysis. We conclude that while G-quadruplex formation may contribute to spontaneous mutation at these sites, deletions actually require the potential for i-motif to form and remain unresolved at neutral pH. 相似文献
899.
K L Waller B M Cooke W Nunomura N Mohandas R L Coppel 《The Journal of biological chemistry》1999,274(34):23808-23813
Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) clusters at electron-dense knob-like structures on the surface of malaria-infected red blood cells and mediates their adhesion to the vascular endothelium. In parasites lacking knobs, vascular adhesion is less efficient, and infected red cells are not able to immobilize successfully under hemodynamic flow conditions even though PfEMP1 is still present on the exterior of the infected red cell. We examined the interaction between the knob-associated histidine-rich protein (KAHRP), the parasite protein upon which knob formation is dependent, and PfEMP1, and we show evidence of a direct interaction between KAHRP and the cytoplasmic region of PfEMP1 (VARC). We have identified three fragments of KAHRP which bind VARC. Two of these KAHRP fragments (K1A and K2A) interact with VARC with binding affinities (K(D(kin))) of 1 x 10(-7) M and 3.3 x 10(-6) M respectively, values comparable to those reported previously for protein-protein interactions in normal and infected red cells. Further experiments localized the high affinity binding regions of KAHRP to the 63-residue histidine-rich and 70-residue 5' repeats. Deletion of these two regions from the KAHRP fragments abolished their ability to bind to VARC. Identification of the critical domains involved in interaction between KAHRP and PfEMP1 may aid development of new therapies to prevent serious complications of P. falciparum malaria. 相似文献
900.