全文获取类型
收费全文 | 1126篇 |
免费 | 65篇 |
国内免费 | 1篇 |
专业分类
1192篇 |
出版年
2023年 | 3篇 |
2022年 | 5篇 |
2021年 | 14篇 |
2020年 | 13篇 |
2019年 | 18篇 |
2018年 | 24篇 |
2017年 | 22篇 |
2016年 | 39篇 |
2015年 | 37篇 |
2014年 | 44篇 |
2013年 | 83篇 |
2012年 | 91篇 |
2011年 | 93篇 |
2010年 | 67篇 |
2009年 | 48篇 |
2008年 | 53篇 |
2007年 | 61篇 |
2006年 | 68篇 |
2005年 | 49篇 |
2004年 | 55篇 |
2003年 | 39篇 |
2002年 | 45篇 |
2001年 | 10篇 |
2000年 | 9篇 |
1999年 | 4篇 |
1998年 | 14篇 |
1997年 | 5篇 |
1996年 | 5篇 |
1995年 | 4篇 |
1994年 | 8篇 |
1993年 | 6篇 |
1992年 | 15篇 |
1991年 | 15篇 |
1990年 | 9篇 |
1989年 | 9篇 |
1988年 | 10篇 |
1987年 | 7篇 |
1986年 | 5篇 |
1985年 | 9篇 |
1984年 | 8篇 |
1983年 | 7篇 |
1982年 | 11篇 |
1981年 | 6篇 |
1980年 | 8篇 |
1979年 | 5篇 |
1978年 | 5篇 |
1977年 | 5篇 |
1976年 | 4篇 |
1973年 | 3篇 |
1968年 | 2篇 |
排序方式: 共有1192条查询结果,搜索用时 15 毫秒
41.
Fernández-Barat L Li Bassi G Ferrer M Bosch A Calvo M Vila J Gabarrús A Martínez-Olondris P Rigol M Esperatti M Luque N Torres A 《FEMS immunology and medical microbiology》2012,65(2):309-317
Confocal laser scanning microscopy (CLSM) helps to observe the biofilms formed in the endotracheal tube (ETT) of ventilated subjects and to determine its structure and bacterial viability using specific dyes. We compared the effect of three different treatments (placebo, linezolid, and vancomycin) on the bacterial biofilm viability captured by CLSM. Eight pigs with pneumonia induced by methicillin-resistant Staphylococcus aureus (MRSA) were ventilated up to 96?h and treated with linezolid, vancomycin, or placebo (controls). ETT images were microscopically examined after staining with the live/dead(?) BacLight(?) Kit (Invitrogen, Barcelona, Spain) with a confocal laser scanning microscope. We analyzed 127 images obtained by CLSM. The median ratio of live/dead bacteria was 0.51, 0.74, and 1 for the linezolid, vancomycin, and control groups, respectively (P?=?0.002 for the three groups); this ratio was significantly lower for the linezolid group, compared with the control group (P?=?0.001). Images showed bacterial biofilm attached and non-attached to the ETT surface but growing within secretions accumulated inside ETT. Systemic treatment with linezolid is associated with a higher proportion of dead bacteria in the ETT biofilm of animals with MRSA pneumonia. Biofilm clusters not necessarily attach to the ETT surface. 相似文献
42.
Murruzzu C Alonso M Canales A Jiménez-Barbero J Riera A 《Carbohydrate research》2007,342(12-13):1805-1812
The synthesis of (4,5,6-13C)-deoxymannojirimycin is described. The route employed is based on Sharpless asymmetric epoxidation of (1,2,3-13C)(E)-2,4-pentadien-1-ol and uses ring-closing metathesis as a key step. The labeled compound may be easily used for protein-binding experiments using NMR spectroscopic methods. 相似文献
43.
44.
Candida cloacae长链脂肪酸醇氧化酶基因的克隆与表达 总被引:3,自引:0,他引:3
Candidacloacae是利用链烃和长链脂肪酸作为碳源来生长的一种工业酵母 .长链脂肪酸在单加氧酶作用下 ,使远离羧基的甲基羟化 ,生成ω 羟脂肪酸 .后者在生物体中通过两条连续的氧化通路进行氧化 (ω氧化通路和 β氧化通路 ) .醇氧化酶是ω氧化通路中的重要组成酶 ,它可以催化链烃或长链脂肪酸分子中的羟基氧化为醛基 ,后者再经其它酶氧化为羧基 .长链脂肪酸通过ω氧化通路生成二羧基化合物 ,它可作为重要的化工原料 ,广泛应用于香料、多聚酰胺、多聚酯、胶类和环内酯抗生素的生成[1] .ω氧化通路中产生的羧基化合物再经 β 氧… 相似文献
45.
46.
Tomàs Pinós Mario Marotta Eduard Gallardo Isabel Illa Jorge Díaz-Manera Emiliano Gonzalez-Vioque Elena García-Arumí Antoni L. Andreu Ramon Martí 《Mitochondrion》2011,11(1):228-233
We report a heteroplasmic novel mutation m.5636T>C in the mt-tRNAAla in a patient with bilateral ptosis and ophthalmoparesis in whom a muscle biopsy showed cytochrome c oxdidase (COX) negative and ragged red fibers. Using laser capture microdissection we have isolated COX negative fibers and COX positive fibers from the muscle of the patient and determined that the mutation load was clearly increased in COX negative muscle fibers. Additionally, the mutated m.5636T nucleotide is conserved in all the mammal and non-mammal species analyzed and might be structurally relevant as it is located in a position involved in the formation of tertiary structure of canonical mitochondrial tRNAs. 相似文献
47.
Barbara Siemieniako Ewa M. Rakowicz-Szulczyńska Antoni Horst 《Molecular and cellular biochemistry》1985,65(2):131-141
Non-histone chromatin proteins synthesized during chicken embryonic liver development were labeled with [3H]tryptophan and [3H]methionine and characterized by electrophoresis. During embryonic development protein/DNA ratio in chromatin was low (1.30-1.62) but synthesis of non-histone protein was high. Especially one characteristic fraction K (MW 18 000), tightly bound with DNA was preferentially associated with DNAase II sensitive, active transcribed sequences. In 7-day old and adult chicken synthesis of all non-histone proteins was low, fraction K was absent or synthesized only in small amounts in association with non-active sequences, however protein/DNA ratio in chromatin was high (2.30-2.33). 相似文献
48.
Mária Sasvári-Székely Gábor Szabó Mária Staub Tatjana Spasokukotskaja Ferenc Antoni 《Biochimica et Biophysica Acta (BBA)/Molecular Cell Research》1983,762(3):452-457
The DNA synthesis system of freshly isolated tonsillar lymphocytes and those stimulated by phytohaemagglutinin were compared by different methods. Both cell populations had high DNA polymerase α and thymidine kinase activities, as well as a high rate of incorporation of [3H]thymidine into DNA. However, the two cell populations differed when their DNA distributions were compared by flow cytometry. Freshly isolated cells contained many less (6%) cells in S phase than were found in phytohaemagglutinin-stimulated lymphocytes (18%) as detected by flow cytometry. The labelling of different subpopulations of lymphocytes was studied by sorting them electrically with a fluorescence-activated cell sorter. Analysis of the radioactivity of [3H]thymidine pulse-labelled cells, sorted according to their DNA content, showed that cells in the G1 peak of DNA distribution had a significant amount of incorporated [3H]thymidine. Sorting of cells according to their size (i.e., by light scattering) revealed that only large cells were labelled with [3H]thymidine. 相似文献
49.
Site-specific integration of the temperate bacteriophage phi adh into the Lactobacillus gasseri chromosome and molecular characterization of the phage (attP) and bacterial (attB) attachment sites. 下载免费PDF全文
The temperate bacteriophage phi adh integrates its genome into the chromosomal DNA of Lactobacillus gasseri ADH by a site-specific recombination process. Southern hybridization analysis of BclI-digested genomic DNA from six relysogenized derivatives of the prophage-cured strain NCK102 displayed phage-chromosomal junction fragments identical to those of the lysogenic parent. The phi adh attachment site sequence, attP, was located within a 365-bp EcoRI-HindIII fragment of phage phi adh. This fragment was cloned and sequenced. DNA sequence analysis revealed striking features common to the attachment sites of other site-specific recombination systems: five direct repeats of the sequence TGTCCCTTTT(C/T) and a 14-bp inverted repeat. Oligonucleotides derived from the sequence of the attP-containing fragment enabled us to amplify predicted junction fragment sequences and thus to identify attL, attR, and attB. The core region was defined as the 16-bp sequence TACACTTCTTAGGAGG. Phage-encoded functions essential for site-specific insertion of phage phi adh were located in a 4.5-kb BclI fragment. This fragment was cloned in plasmid pSA34 to generate the insertional vector pTRK182. Plasmid pTRK182 was introduced into L. gasseri NCK102 by electroporation. Hybridization analysis showed that a single copy of pTRK182 had integrated at the attB site of the NCK102 erythromycin-resistant transformants. This is the first site-specific recombination system described in lactobacilli, as well as the first attP-based site-specific integration vector constructed for L. gasseri ADH. 相似文献
50.
Tomoaki Hishida Eric Vazquez-Ferrer Yuriko Hishida-Nozaki Ignacio Sancho-Martinez Yuta Takahashi Fumiyuki Hatanaka Jun Wu Alejandro Ocampo Pradeep Reddy Min-Zu Wu Laurie Gerken Reuben J. Shaw Concepcion Rodriguez Esteban Christopher Benner Hiroshi Nakagawa Pedro Guillen Garcia Estrella Nu ez Delicado Antoni Castells Josep M. Campistol Guang-Hui Liu Juan Carlos Izpisua Belmonte 《蛋白质与细胞》2019,10(7):485
Identification of the precise molecular pathways involved in oncogene-induced transformation may help us gain a better understanding of tumor initiation and promotion. Here, we demonstrate that SOX2+ foregut epithelial cells are prone to oncogenic transformation upon mutagenic insults, such as KrasG12D and p53 deletion. GFP-based lineage-tracing experiments indicate that SOX2+ cells are the cells-of-origin of esophagus and stomach hyperplasia. Our observations indicate distinct roles for oncogenic KRAS mutation and P53 deletion. p53 homozygous deletion is required for the acquisition of an invasive potential, and KrasG12D expression, but not p53 deletion, suffices for tumor formation. Global gene expression analysis reveals secreting factors upregulated in the hyperplasia induced by oncogenic KRAS and highlights a crucial role for the CXCR2 pathway in driving hyperplasia. Collectively, the array of genetic models presented here demonstrate that stratified epithelial cells are susceptible to oncogenic insults, which may lead to a better understanding of tumor initiation and aid in the design of new cancer therapeutics. 相似文献