全文获取类型
收费全文 | 1609篇 |
免费 | 76篇 |
国内免费 | 72篇 |
出版年
2023年 | 20篇 |
2022年 | 18篇 |
2021年 | 30篇 |
2020年 | 39篇 |
2019年 | 63篇 |
2018年 | 107篇 |
2017年 | 47篇 |
2016年 | 23篇 |
2015年 | 29篇 |
2014年 | 97篇 |
2013年 | 112篇 |
2012年 | 80篇 |
2011年 | 92篇 |
2010年 | 66篇 |
2009年 | 67篇 |
2008年 | 79篇 |
2007年 | 94篇 |
2006年 | 62篇 |
2005年 | 53篇 |
2004年 | 26篇 |
2003年 | 30篇 |
2002年 | 31篇 |
2001年 | 35篇 |
2000年 | 11篇 |
1999年 | 16篇 |
1998年 | 18篇 |
1997年 | 13篇 |
1996年 | 23篇 |
1995年 | 11篇 |
1994年 | 13篇 |
1993年 | 8篇 |
1991年 | 8篇 |
1990年 | 6篇 |
1989年 | 11篇 |
1988年 | 8篇 |
1987年 | 5篇 |
1986年 | 6篇 |
1985年 | 37篇 |
1984年 | 42篇 |
1983年 | 21篇 |
1982年 | 44篇 |
1981年 | 21篇 |
1980年 | 21篇 |
1979年 | 27篇 |
1978年 | 19篇 |
1977年 | 9篇 |
1976年 | 15篇 |
1975年 | 11篇 |
1974年 | 16篇 |
1973年 | 5篇 |
排序方式: 共有1757条查询结果,搜索用时 15 毫秒
61.
M. Dach A. Accorsi C. Pierotti F. Vetrano R. Mantovani G. Guidi R. Conti P. Nicolini 《Bioelectromagnetics》1993,14(4):383-391
An attempt has been made to understand whether 50 Hz electric and magnetic fields (EMFs) are involved in producing bioeffects by exposing human erythrocytes in vitro. The study evaluated some key glycolytic enzymes, glucose consumption, lactate production, energy charge, 2,3-diphosphoglycerate, and reduced glutathione levels. all of which are biochemical parameters significant to erythrocyte function. Cells exposed to individual or superimposed EMFs have not shown any significant difference compared with the controls. © 1993 Wiley-Liss. Inc. 相似文献
62.
Neus Calbet‐Llopart Mirella Pascini‐Garrigos Gemma Tell‐Martí Miriam Potrony Vanessa Martins da Silva Alicia Barreiro Susana Puig Guillaume Captier Isabelle James Nathalie Degardin Cristina Carrera Josep Malvehy Heather C. Etchevers Joan Anton Puig‐Butill 《Pigment cell & melanoma research》2020,33(5):685-694
Congenital melanocytic nevi (CMN) are cutaneous malformations whose prevalence is inversely correlated with projected adult size. CMN are caused by somatic mutations, but epidemiological studies suggest that germline genetic factors may influence CMN development. In CMN patients from the U.K., genetic variants in MC1R, such as p.V92M and loss‐of‐function variants, have been previously associated with larger CMN. We analyzed the association of MC1R variants with CMN characteristics in two distinct cohorts of medium‐to‐giant CMN patients from Spain (N = 113) and from France, Norway, Canada, and the United States (N = 53), similar at the clinical and phenotypical level except for the number of nevi per patient. We found that the p.V92M or loss‐of‐function MC1R variants either alone or in combination did not correlate with CMN size, in contrast to the U.K. CMN patients. An additional case–control analysis with 259 unaffected Spanish individuals showed a higher frequency of MC1R compound heterozygous or homozygous variant genotypes in Spanish CMN patients compared to the control population (15.9% vs. 9.3%; p = .075). Altogether, this study suggests that MC1R variants are not associated with CMN size in these non‐UK cohorts. Additional studies are required to define the potential role of MC1R as a risk factor in CMN development. 相似文献
63.
在2016年和2017年的5—8月,我们对川西马尔康麝场圈养林麝(Moschus berezovskii)的麝香分泌进行了行为与生理监测,对麝香分泌的各阶段进行了准确判定,记录了泌香启动、泌香盛期开始、泌香盛期终止及泌香结束的时间阶段及持续时间长,分析了林麝麝香分泌的时间阶段与体重和年龄等因素的关系。结果表明,马尔康麝场的雄性林麝平均泌香启动日在6月16日[(167.06±7.75)d,n=141],于6月17日进入泌香盛期[(168.52±7.67)d,n=141],6月21日[(172.17±7.26)d, n=138]泌香活动减弱,至6月25日[(176.27±8.11)d, n=131]泌香结束;雄麝体重与其泌香启动、泌香盛期停止及泌香结束时间呈显著负相关(rPS = -0.234,PPS =0.028;r VSF = -0.215,PVSF = 0.047;r SE = -0.229,PSE = 0.043),即雄麝的体重越大,其泌香越早;各年龄组间的平均泌香时长差异显著(F 17, 113 = 3.482, P = 0.003),其中2岁雄麝平均泌香时长最长[(13.07±2.08)d, n=20],显著高于3岁[(9.38±0.76)d, n=12, P = 0.042]和4岁[(7.80±1.60)d, n=5, P = 0.013]个体;马尔康林麝平均泌香量为(11.85g±0.96)g, (n=114),随泌香时长延长有增加趋势,但不显著(P = 0.854)。基于上述林麝雄体的泌香时间、泌香量与年龄和体重等因素间的关联,可对圈养的林麝个体间的泌香力、泌香量等进行区分和预判,作为圈养林麝驯养生产力优化的依据,并可为圈养林麝优质品系的选育提供参考。 相似文献
64.
Nenad Bukvic Carla CesaranoCaterina Ceccarini Marianna BrunoMaria Rosaria Lipsi Maria Grazia GallicchioMaria Assunta Carboni Lucia ValenteGiulia Cotoia Raffaele Antonetti 《Gene》2013
Herein, we describe a case of an infertile man detected in postnatal diagnosis with FISH characterization and array-CGH used for genome-wide screening which allowed the identification of a complex rearrangement involving sex chromosomes, apparently without severe phenotypic consequences. The deletion detected in our patient has been compared with previously reported cases leading us to propose a hypothetical diagnostic algorithm that would be useful in similar clinical situations, with imperative multi disciplinary approach integrated with genetic counseling. Our patient, uniquely of reproductive age, is one of six reported cases of duplication of Xp22.3 (~ 8.4 Mb) segment and contemporary deletion of Yq (~ 42.9 Mb) with final karyotype as follows:
- 46,X,der(Y),t(X;Y)(Ypter → Yq11.221::Xp22.33 → Xpter).ish der(Y) (Yptel+,Ycen+,RP11-529I21+,RP11-506M9-Yqtel −,Xptel +). arrXp22.33p22.31(702–8,395,963, 8,408,289x1), Yq11.221q12 (14,569,317x1, 14,587,321–57,440,839x0) 相似文献
65.
66.
Lin Wu Arend van Peer Wenhua Song Hong Wang Mingjie Chen Qi Tan Chunyan Song Meiyan Zhang Dapeng Bao 《Gene》2013
During the life cycle of heterothallic tetrapolar Agaricomycetes such as Lentinula edodes (Berk.) Pegler, the mating type system, composed of unlinked A and B loci, plays a vital role in controlling sexual development and resulting formation of the fruit body. L. edodes is produced worldwide for consumption and medicinal purposes, and understanding its sexual development is therefore of great importance. A considerable amount of mating type factors has been indicated over the past decades but few genes have actually been identified, and no complete genetic structures of L. edodes B mating-type loci are available. In this study, we cloned the matB regions from two mating compatible L. edodes strains, 939P26 and 939P42. Four pheromone receptors were identified on each new matB region, together with three and four pheromone precursor genes in the respective strains. Gene polymorphism, phylogenetic analysis and distribution of pheromone receptors and pheromone precursors clearly indicate a bipartite matB locus, each sublocus containing a pheromone receptor and one or two pheromone precursors. Detailed sequence comparisons of genetic structures between the matB regions of strains 939P42, 939P26 and a previously reported strain SUP2 further supported this model and allowed identification of the B mating type subloci borders. Mating studies confirmed the control of B mating by the identified pheromone receptors and pheromones in L. edodes. 相似文献
67.
Asheesh Gupta Pinar Avci Magesh Sadasivam Rakkiyappan Chandran Nivaldo Parizotto Daniela Vecchio Wanessa C.M.A. de Melo Tianhong Dai Long Y. Chiang Michael R. Hamblin 《Biotechnology advances》2013
Phototherapy can be used in two completely different but complementary therapeutic applications. While low level laser (or light) therapy (LLLT) uses red or near-infrared light alone to reduce inflammation, pain and stimulate tissue repair and regeneration, photodynamic therapy (PDT) uses the combination of light plus non-toxic dyes (called photosensitizers) to produce reactive oxygen species that can kill infectious microorganisms and cancer cells or destroy unwanted tissue (neo-vascularization in the choroid, atherosclerotic plaques in the arteries). The recent development of nanotechnology applied to medicine (nanomedicine) has opened a new front of advancement in the field of phototherapy and has provided hope for the development of nanoscale drug delivery platforms for effective killing of pathological cells and to promote repair and regeneration. Despite the well-known beneficial effects of phototherapy and nanomaterials in producing the killing of unwanted cells and promoting repair and regeneration, there are few reports that combine all three elements i.e. phototherapy, nanotechnology and, tissue repair and regeneration. However, these areas in all possible binary combinations have been addressed by many workers. The present review aims at highlighting the combined multi-model applications of phototherapy, nanotechnology and, reparative and regeneration medicine and outlines current strategies, future applications and limitations of nanoscale-assisted phototherapy for the management of cancers, microbial infections and other diseases, and to promote tissue repair and regeneration. 相似文献
68.
69.
Ziguo Zhang Leifu ChangJing Yang Nora ConinKiran Kulkarni David Barford 《Journal of molecular biology》2013
The anaphase-promoting complex or cyclosome (APC/C) is a large E3 RING-cullin ubiquitin ligase composed of between 14 and 15 individual proteins. A striking feature of the APC/C is that only four proteins are involved in directly recognizing target proteins and catalyzing the assembly of a polyubiquitin chain. All other subunits, which account for > 80% of the mass of the APC/C, provide scaffolding functions. A major proportion of these scaffolding subunits are structurally related. In metazoans, there are four canonical tetratricopeptide repeat (TPR) proteins that form homo-dimers (Apc3/Cdc27, Apc6/Cdc16, Apc7 and Apc8/Cdc23). Here, we describe the crystal structure of the N-terminal homo-dimerization domain of Schizosaccharomyces pombe Cdc23 (Cdc23Nterm). Cdc23Nterm is composed of seven contiguous TPR motifs that self-associate through a related mechanism to those of Cdc16 and Cdc27. Using the Cdc23Nterm structure, we generated a model of full-length Cdc23. The resultant “V”-shaped molecule docks into the Cdc23-assigned density of the human APC/C structure determined using negative stain electron microscopy (EM). Based on sequence conservation, we propose that Apc7 forms a homo-dimeric structure equivalent to those of Cdc16, Cdc23 and Cdc27. The model is consistent with the Apc7-assigned density of the human APC/C EM structure. The four canonical homo-dimeric TPR proteins of human APC/C stack in parallel on one side of the complex. Remarkably, the uniform relative packing of neighboring TPR proteins generates a novel left-handed suprahelical TPR assembly. This finding has implications for understanding the assembly of other TPR-containing multimeric complexes. 相似文献
70.