全文获取类型
收费全文 | 1396篇 |
免费 | 69篇 |
出版年
2022年 | 18篇 |
2021年 | 33篇 |
2020年 | 15篇 |
2019年 | 12篇 |
2018年 | 27篇 |
2017年 | 20篇 |
2016年 | 42篇 |
2015年 | 72篇 |
2014年 | 77篇 |
2013年 | 107篇 |
2012年 | 112篇 |
2011年 | 109篇 |
2010年 | 59篇 |
2009年 | 45篇 |
2008年 | 82篇 |
2007年 | 84篇 |
2006年 | 65篇 |
2005年 | 65篇 |
2004年 | 63篇 |
2003年 | 44篇 |
2002年 | 50篇 |
2001年 | 18篇 |
2000年 | 19篇 |
1999年 | 9篇 |
1998年 | 16篇 |
1997年 | 11篇 |
1996年 | 15篇 |
1995年 | 4篇 |
1994年 | 7篇 |
1993年 | 10篇 |
1992年 | 7篇 |
1991年 | 17篇 |
1990年 | 8篇 |
1989年 | 11篇 |
1988年 | 7篇 |
1987年 | 10篇 |
1986年 | 6篇 |
1985年 | 8篇 |
1984年 | 14篇 |
1983年 | 5篇 |
1982年 | 5篇 |
1981年 | 4篇 |
1980年 | 4篇 |
1979年 | 4篇 |
1974年 | 5篇 |
1973年 | 4篇 |
1972年 | 3篇 |
1949年 | 3篇 |
1934年 | 2篇 |
1919年 | 2篇 |
排序方式: 共有1465条查询结果,搜索用时 281 毫秒
121.
A new epigonid fish, Epigonus cavaticus, is described on the basis of eight specimens (59.2–69.5 in standard length: SL) collected from a cave at depth 20 m, southern
fringing reef of Ngemelis Island, Palau. The species differs from other congeners by having minute teeth on both jaws, no
opercular spine, pyloric caeca 7–8, gill rakers 25–27, total pored lateral line scales 48–50, dorsal fin rays VII-I, 10–11
(mode VII-I, 10), pectoral fin rays 16, vertebrae 10 + 15, body depth 21.4–25.0% SL, pectoral fin length 22.7–24.6% SL, eye
diameter 44.4–47.5% head length: HL, upper jaw length 40.2–42.5% HL. Four paratypes (63.7–66.8 mm SL) of the new species are
female with mature gonads, it is the smallest in size at sexual maturity among the congeners. 相似文献
122.
Alpi A Amrhein N Bertl A Blatt MR Blumwald E Cervone F Dainty J De Michelis MI Epstein E Galston AW Goldsmith MH Hawes C Hell R Hetherington A Hofte H Juergens G Leaver CJ Moroni A Murphy A Oparka K Perata P Quader H Rausch T Ritzenthaler C Rivetta A Robinson DG Sanders D Scheres B Schumacher K Sentenac H Slayman CL Soave C Somerville C Taiz L Thiel G Wagner R 《Trends in plant science》2007,12(4):135-136
123.
Carlo Alviggi Alberto Revelli Paola Anserini Antonio Ranieri Luigi Fedele Ida Strina Marco Massobrio Nicola Ragni Giuseppe De Placido 《Reproductive biology and endocrinology : RB&E》2007,5(1):45-7
Background
Multifollicular ovarian stimulation (MOS) is widely used in IVF and the compliance to treatment is deeply influenced by the tolerability of the medication(s) used and by the ease of self-administration. This prospective, controlled, randomised, parallel group open label, multicenter, phase III, equivalence study has been aimed to compare the clinical effectiveness (in terms of oocytes obtained) and tolerability of subcutaneous (s.c.) self-administered versus classical intramuscular (i.m.) injections of Merional, a new highly-purified hMG preparation. 相似文献124.
Said Aoufouchi Annie De Smet Frédéric Delbos Camille Gelot Ida Chiara Guerrera Jean-Claude Weill Claude-Agnès Reynaud 《Molecular and cellular biology》2015,35(17):3059-3070
Mice derived from the 129 strain have a nonsense codon mutation in exon 2 of the polymerase iota (Polι) gene and are therefore considered Polι deficient. When we amplified Polι mRNA from 129/SvJ or 129/Ola testes, only a small fraction of the full-length cDNA contained the nonsense mutation; the major fraction corresponded to a variant Polι isoform lacking exon 2. Polι mRNA lacking exon 2 contains an open reading frame, and the corresponding protein was detected using a polyclonal antibody raised against the C terminus of the murine Polι protein. The identity of the corresponding protein was further confirmed by mass spectrometry. Although the variant protein was expressed at only 5 to 10% of the level of wild-type Polι, it retained de novo DNA synthesis activity, the capacity to form replication foci following UV irradiation, and the ability to rescue UV light sensitivity in Polι−/− embryonic fibroblasts derived from a new, fully deficient Polι knockout (KO) mouse line. Furthermore, in vivo treatment of 129-derived male mice with Velcade, a drug that inhibits proteasome function, stabilized and restored a substantial amount of the variant Polι in these animals, indicating that its turnover is controlled by the proteasome. An analysis of two xeroderma pigmentosum-variant (XPV) cases corresponding to missense mutants of Polη, a related translesion synthesis (TLS) polymerase in the same family, similarly showed a destabilization of the catalytically active mutant protein by the proteasome. Collectively, these data challenge the prevailing hypothesis that 129-derived strains of mice are completely deficient in Polι activity. The data also document, both for 129-derived mouse strains and for some XPV patients, new cases of genetic defects corresponding to the destabilization of an otherwise functional protein, the phenotype of which is reversible by proteasome inhibition. 相似文献
125.
Komlavi Anani Afanou Anne Straumfors Asbj?rn Skogstad Ajay P. Nayak Ida Skaar Linda Hjeljord Arne Tronsmo Wijnand Eduard Brett James Green 《Applied and environmental microbiology》2015,81(17):5794-5803
Submicronic fungal fragments have been observed in in vitro aerosolization experiments. The occurrence of these particles has therefore been suggested to contribute to respiratory health problems observed in mold-contaminated indoor environments. However, the role of submicronic fragments in exacerbating adverse health effects has remained unclear due to limitations associated with detection methods. In the present study, we report the development of an indirect immunodetection assay that utilizes chicken polyclonal antibodies developed against spores from Aspergillus versicolor and high-resolution field emission scanning electron microscopy (FESEM). Immunolabeling was performed with A. versicolor fragments immobilized and fixed onto poly-l-lysine-coated polycarbonate filters. Ninety percent of submicronic fragments and 1- to 2-μm fragments, compared to 100% of >2-μm fragments generated from pure freeze-dried mycelial fragments of A. versicolor, were positively labeled. In proof-of-concept experiments, air samples collected from moldy indoor environments were evaluated using the immunolabeling technique. Our results indicated that 13% of the total collected particles were derived from fungi. This fraction comprises 79% of the fragments that were detected by immunolabeling and 21% of the spore particles that were morphologically identified. The methods reported in this study enable the enumeration of fungal particles, including submicronic fragments, in a complex heterogeneous environmental sample. 相似文献
126.
Pressure pain threshold of the cervico‐facial muscles in healthy elderly people: the role of gender,age and dominance
下载免费PDF全文
![点击此处可从《Gerodontology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
127.
128.
Dominika Staniec Miroslaw Ksiazek Ida B. Th?gersen Jan J. Enghild Aneta Sroka Danuta Bryzek Matthew Bogyo Magnus Abrahamson Jan Potempa 《The Journal of biological chemistry》2015,290(45):27248-27260
Porphyromonas gingivalis is a peptide-fermenting asaccharolytic periodontal pathogen. Its genome contains several genes encoding cysteine peptidases other than gingipains. One of these genes (PG1055) encodes a protein called Tpr (thiol protease) that has sequence similarity to cysteine peptidases of the papain and calpain families. In this study we biochemically characterize Tpr. We found that the 55-kDa Tpr inactive zymogen proteolytically processes itself into active forms of 48, 37, and 33 kDa via sequential truncations at the N terminus. These processed molecular forms of Tpr are associated with the bacterial outer membrane where they are likely responsible for the generation of metabolic peptides required for survival of the pathogen. Both autoprocessing and activity were dependent on calcium concentrations >1 mm, consistent with the protein''s activity within the intestinal and inflammatory milieus. Calcium also stabilized the Tpr structure and rendered the protein fully resistant to proteolytic degradation by gingipains. Together, our findings suggest that Tpr is an example of a bacterial calpain, a calcium-responsive peptidase that may generate substrates required for the peptide-fermenting metabolism of P. gingivalis. Aside from nutrient generation, Tpr may also be involved in evasion of host immune response through degradation of the antimicrobial peptide LL-37 and complement proteins C3, C4, and C5. Taken together, these results indicate that Tpr likely represents an important pathogenesis factor for P. gingivalis. 相似文献
129.
A miRNA Signature in Human Cord Blood Stem and Progenitor Cells as Potential Biomarker of Specific Acute Myeloid Leukemia Subtypes
下载免费PDF全文
![点击此处可从《Journal of cellular physiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
130.
Diogo Robl Priscila da Silva Delabona Patrícia dos Santos Costa Deise Juliana da Silva Lima Sarita Candida Rabelo Ida Chapaval Pimentel 《Biocatalysis and Biotransformation》2015,33(3):175-187
Fungal xylanases have been widely studied and various production methods have been proposed using submerged and solid-state fermentation. This class of enzyme is used to supplement cellulolytic enzyme cocktails in order to enhance the enzymatic hydrolysis of plant cell walls. The present work investigates the production of xylanase and other accessory enzymes by a recently isolated endophytic Aspergillus niger DR02 strain, using the pentose-rich liquor from hydrothermal pretreatment of sugarcane bagasse as carbon source. Batch and fed-batch submerged cultivation approaches were developed in order to minimize the toxicity of the liquor and increase enzyme production. Maximum xylanase activities obtained were 458.1 U/mL for constant fed-batch, 428.1 U/mL for exponential fed-batch, and 264.37 U/mL for pulsed fed-batch modes. The results indicated that carbon-limited fed-batch cultivation can reduce fungal catabolite repression, as well as overcome possible negative effects of toxic compounds present in the pentose-rich liquor. Enzymatic panel and mass spectrometric analyses of the fed-batch A. niger secretome showed high levels of xylanolytic enzymes (GH10, GH11, and GH62 Cazy families), together with cellobiohydrolase (G6 and GH7), β-glucosidase, β-xylosidase (GH3), and feruloyl esterase (CE1) accessory enzyme activities. The yields of glucose and xylose from enzymatic hydrolysis of hydrothermally pretreated sugarcane bagasse increased by 43.7 and 65.3%, respectively, when a commercial cellulase preparation was supplemented with the A. niger DR02 constant fed-batch enzyme complex. 相似文献