全文获取类型
收费全文 | 945篇 |
免费 | 125篇 |
专业分类
1070篇 |
出版年
2023年 | 6篇 |
2022年 | 13篇 |
2021年 | 27篇 |
2020年 | 5篇 |
2019年 | 10篇 |
2018年 | 23篇 |
2017年 | 16篇 |
2016年 | 34篇 |
2015年 | 43篇 |
2014年 | 41篇 |
2013年 | 50篇 |
2012年 | 78篇 |
2011年 | 83篇 |
2010年 | 55篇 |
2009年 | 39篇 |
2008年 | 46篇 |
2007年 | 44篇 |
2006年 | 47篇 |
2005年 | 35篇 |
2004年 | 30篇 |
2003年 | 28篇 |
2002年 | 25篇 |
2001年 | 15篇 |
2000年 | 24篇 |
1999年 | 15篇 |
1998年 | 7篇 |
1997年 | 6篇 |
1996年 | 8篇 |
1995年 | 8篇 |
1994年 | 10篇 |
1993年 | 5篇 |
1992年 | 11篇 |
1991年 | 14篇 |
1990年 | 15篇 |
1989年 | 11篇 |
1988年 | 13篇 |
1987年 | 12篇 |
1986年 | 16篇 |
1985年 | 10篇 |
1984年 | 14篇 |
1982年 | 6篇 |
1981年 | 6篇 |
1979年 | 5篇 |
1977年 | 4篇 |
1976年 | 5篇 |
1971年 | 5篇 |
1969年 | 4篇 |
1968年 | 7篇 |
1967年 | 4篇 |
1937年 | 5篇 |
排序方式: 共有1070条查询结果,搜索用时 15 毫秒
51.
Bell LM Leong ML Kim B Wang E Park J Hemmings BA Firestone GL 《The Journal of biological chemistry》2000,275(33):25262-25272
52.
Production of recombinant snakehead rhabdovirus: the NV protein is not required for viral replication 总被引:2,自引:0,他引:2 下载免费PDF全文
Snakehead rhabdovirus (SHRV) affects warm water fish in Southeast Asia and belongs to the genus Novirhabdovirus by virtue of its nonvirion gene (NV). Because SHRV grows best at temperatures between 28 and 31 degrees C, we were able to use the T7 expression system to produce viable recombinant SHRV from a cloned cDNA copy of the viral genome. Expression of a positive-strand RNA copy of the 11, 550-nucleotide SHRV genome along with the viral nucleocapsid (N), phosphoprotein (P), and polymerase (L) proteins resulted in the generation of infectious SHRV in cells preinfected with a vaccinia virus vector for T7 polymerase expression. Recombinant virus production was verified by detection of a unique restriction site engineered into the SHRV genome between the NV and L genes. Since we were now able to begin examining the function of the NV gene, we constructed a recombinant virus containing a nonsense mutation located 22 codons into the coding sequence of the NV protein. The NV knockout virus was produced at a concentration as high as that of wild-type virus in cultured fish cells, and the resulting virions appeared to be identical to the wild-type virions in electron micrographs. These initial studies suggest that NV has no critical function in SHRV replication in cultured fish cells. 相似文献
53.
Steve Horvath Abu NM Nazmul-Hossain Rodney PE Pollard Frans GM Kroese Arjan Vissink Cees GM Kallenberg Fred KL Spijkervet Hendrika Bootsma Sara A Michie Sven U Gorr Ammon B Peck Chaochao Cai Hui Zhou David TW Wong 《Arthritis research & therapy》2012,14(6):1-13
Bone tissue has an exceptional quality to regenerate to native tissue in response to injury. However, the fracture repair process requires mechanical stability or a viable biological microenvironment or both to ensure successful healing to native tissue. An improved understanding of the molecular and cellular events that occur during bone repair and remodeling has led to the development of biologic agents that can augment the biological microenvironment and enhance bone repair. Orthobiologics, including stem cells, osteoinductive growth factors, osteoconductive matrices, and anabolic agents, are available clinically for accelerating fracture repair and treatment of compromised bone repair situations like delayed unions and nonunions. Preclinical and clinical studies using biologic agents like recombinant bone morphogenetic proteins have demonstrated an efficacy similar or better than that of autologous bone graft in acute fracture healing. A lack of standardized outcome measures for comparison of biologic agents in clinical fracture repair trials, frequent off-label use, and a limited understanding of the biological activity of these agents at the bone repair site have limited their efficacy in clinical applications. 相似文献
54.
Aaron Leong Kaberi Dasgupta Sasha Bernatsky Diane Lacaille Antonio Avina-Zubieta Elham Rahme 《PloS one》2013,8(10)
Objectives
Health administrative data are frequently used for diabetes surveillance. We aimed to determine the sensitivity and specificity of a commonly-used diabetes case definition (two physician claims or one hospital discharge abstract record within a two-year period) and their potential effect on prevalence estimation.Methods
Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, we searched Medline (from 1950) and Embase (from 1980) databases for validation studies through August 2012 (keywords: “diabetes mellitus”; “administrative databases”; “validation studies”). Reviewers abstracted data with standardized forms and assessed quality using Quality Assessment of Diagnostic Accuracy Studies (QUADAS) criteria. A generalized linear model approach to random-effects bivariate regression meta-analysis was used to pool sensitivity and specificity estimates. We applied correction factors derived from pooled sensitivity and specificity estimates to prevalence estimates from national surveillance reports and projected prevalence estimates over 10 years (to 2018).Results
The search strategy identified 1423 abstracts among which 11 studies were deemed relevant and reviewed; 6 of these reported sensitivity and specificity allowing pooling in a meta-analysis. Compared to surveys or medical records, sensitivity was 82.3% (95%CI 75.8, 87.4) and specificity was 97.9% (95%CI 96.5, 98.8). The diabetes case definition underestimated prevalence when it was ≤10.6% and overestimated prevalence otherwise.Conclusion
The diabetes case definition examined misses up to one fifth of diabetes cases and wrongly identifies diabetes in approximately 2% of the population. This may be sufficiently sensitive and specific for surveillance purposes, in particular monitoring prevalence trends. Applying correction factors to adjust prevalence estimates from this definition may be helpful to increase accuracy of estimates. 相似文献55.
56.
Emily M. Mallick John J. Garber Vijay K. Vanguri Sowmya Balasubramanian Timothy Blood Stacie Clark Didier Vingadassalom Christopher Louissaint Beth McCormick Scott B. Snapper John M. Leong 《Cellular microbiology》2014,16(9):1405-1424
Enterohaemorrhagic Escherichia coli (EHEC) colonizes the intestine and causes bloody diarrhoea and kidney failure by producing Shiga toxin. Upon binding intestinal cells, EHEC triggers a change in host cell shape, generating actin ‘pedestals’ beneath bound bacteria. To investigate the importance of pedestal formation to disease, we infected genetically engineered mice incapable of supporting pedestal formation by an EHEC‐like mouse pathogen, or wild type mice with a mutant of that pathogen incapable of generating pedestals. We found that pedestal formation promotes attachment of bacteria to the intestinal mucosa and vastly increases the severity of Shiga toxin‐mediated disease. 相似文献
57.
58.
Catherine Ronin Herman van Halbeek Johannah GM Mutsaers Johannes F G Vliegenthart 《Glycoconjugate journal》1987,4(3):247-254
The lipid-linked precursor ofN-type glycoprotein oligosaccharides was isolated from porcine thyroid microsomes after in cubation with UDP[3H] Glucose. The carbohydrate was released from dolichol pyrophosphate by mild acid hydrolysis, purified by gel filtration and characterized by 500-MHz1H-NMR spectroscopy in combination with enzymatic degradation. The parent oligosaccharide was found to be Glc3Man9Glc-NAc2. The three glucose residues are present in the linear sequence Glcα1-2Glα1-3 Glc, the latter being α(1-3)-linked to one of the mannose residues. In order to establish the branch location of the triglucosyl unit, the parent compound was digested with jack-bean α-mannosidase. The oligosaccharide product was purified by gel filtration, and identified by1H-NMR as Glc3Man5GlcNAc2 lacking the mannose residues A, D2, B and D3. Therefore, the structure of the precursor oligosaccharide is as follows: $$\begin{gathered} c b a D_1 C 4 \hfill \\ Glc\alpha 1 - 2Glc\alpha 1 - 3Glc\alpha 1 - 3Man\alpha 1 - 2Man\alpha 1 - 2Man\alpha 1 \hfill \\ 3 \swarrow 3 2 1 \hfill \\ Man\alpha 1 - 2Man\alpha 1 Man\beta 1 - 4GlcNAc\beta 1 - 4GlcNAc \hfill \\ D_{2 } A 3 6 \hfill \\ Man\alpha 1 \hfill \\ 6 \hfill \\ Man\alpha 1 - 2Man\alpha 1 \nwarrow 4 \hfill \\ D_3 B \hfill \\ \end{gathered} $$ 相似文献
59.
Background
A recent study on expression and function of the ortholog of the Drosophila collier (col) gene in various arthropods including insects, crustaceans and chelicerates suggested a de novo function of col in the development of the appendage-less intercalary segment of insects. However, this assumption was made on the background of the now widely-accepted Pancrustacea hypothesis that hexapods represent an in-group of the crustaceans. It was therefore assumed that the expression of col in myriapods would reflect the ancestral state like in crustaceans and chelicerates, i.e. absence from the premandibular/intercalary segment and hence no function in its formation. 相似文献60.
de Groot L Hinkema H Westra J Smit AJ Kallenberg CG Bijl M Posthumus MD 《Arthritis research & therapy》2011,13(6):R205