全文获取类型
收费全文 | 1262篇 |
免费 | 106篇 |
国内免费 | 1篇 |
专业分类
1369篇 |
出版年
2023年 | 7篇 |
2022年 | 24篇 |
2021年 | 35篇 |
2020年 | 16篇 |
2019年 | 22篇 |
2018年 | 26篇 |
2017年 | 24篇 |
2016年 | 29篇 |
2015年 | 44篇 |
2014年 | 51篇 |
2013年 | 67篇 |
2012年 | 91篇 |
2011年 | 94篇 |
2010年 | 43篇 |
2009年 | 42篇 |
2008年 | 69篇 |
2007年 | 69篇 |
2006年 | 57篇 |
2005年 | 55篇 |
2004年 | 55篇 |
2003年 | 56篇 |
2002年 | 35篇 |
2001年 | 26篇 |
2000年 | 18篇 |
1999年 | 22篇 |
1998年 | 13篇 |
1997年 | 11篇 |
1996年 | 15篇 |
1995年 | 15篇 |
1994年 | 14篇 |
1993年 | 6篇 |
1992年 | 10篇 |
1991年 | 22篇 |
1990年 | 11篇 |
1989年 | 9篇 |
1988年 | 11篇 |
1987年 | 9篇 |
1986年 | 10篇 |
1983年 | 7篇 |
1982年 | 7篇 |
1979年 | 6篇 |
1978年 | 7篇 |
1976年 | 8篇 |
1975年 | 6篇 |
1974年 | 7篇 |
1973年 | 8篇 |
1971年 | 6篇 |
1970年 | 11篇 |
1969年 | 6篇 |
1968年 | 10篇 |
排序方式: 共有1369条查询结果,搜索用时 50 毫秒
91.
Under physiological conditions of loading, articular cartilage is subjected to both compressive strains, normal to the articular surface, and tensile strains, tangential to the articular surface. Previous studies have shown that articular cartilage exhibits a much higher modulus in tension than in compression, and theoretical analyses have suggested that this tension–compression nonlinearity enhances the magnitude of interstitial fluid pressurization during loading in unconfined compression, above a theoretical threshold of 33% of the average applied stress. The first hypothesis of this experimental study is that the peak fluid load support in unconfined compression is significantly greater than the 33% theoretical limit predicted for porous permeable tissues modeled with equal moduli in tension and compression. The second hypothesis is that the peak fluid load support is higher at the articular surface side of the tissue samples than near the deep zone, because the disparity between the tensile and compressive moduli is greater at the surface zone. Ten human cartilage samples from six patellofemoral joints, and 10 bovine cartilage specimens from three calf patellofemoral joints were tested in unconfined compression. The peak fluid load support was measured at 79±11% and 69±15% at the articular surface and deep zone of human cartilage, respectively, and at 94±4% and 71±8% at the articular surface and deep zone of bovine calf cartilage, respectively. Statistical analyses confirmed both hypotheses of this study. These experimental results suggest that the tension–compression nonlinearity of cartilage is an essential functional property of the tissue which makes interstitial fluid pressurization the dominant mechanism of load support in articular cartilage. 相似文献
92.
Evaluation of genetic diversity among Pseudomonas citronellolis strains isolated from oily sludge-contaminated sites 总被引:2,自引:0,他引:2
Bhattacharya D Sarma PM Krishnan S Mishra S Lal B 《Applied and environmental microbiology》2003,69(3):1435-1441
The diversity among a set of bacterial strains that have the capacity to degrade total petroleum hydrocarbons (TPH) in soil contaminated with oily sludge (hazardous hydrocarbon waste from oil refineries) was determined. TPH is composed of alkane, aromatics, nitrogen-, sulfur-, and oxygen-containing compound, and asphaltene fractions of crude oil. The 150 bacterial isolates which could degrade TPH were isolated from soil samples obtained from diverse geoclimatic regions of India. All the isolates were biochemically characterized and identified with a Biolog microbial identification system and by 16S rDNA sequencing. Pseudomonas citronellolis predominated among the 150 isolates obtained from six different geographically diverse samplings. Of the isolates, 29 strains of P. citronellolis were selected for evaluating their genetic diversity. This was performed by molecular typing with repetitive sequence (Rep)-based PCR with primer sets ERIC (enterobacterial repetitive intergenic consensus), REP (repetitive extragenic palindromes), and BOXAIR and PCR-based ribotyping. Strain-specific and unique genotypic fingerprints were distinguished by these molecular typing strategies. The 29 strains of P. citronellolis were separated into 12 distinguishable genotypic groups by Rep-PCR and into seven genomic patterns by PCR-based ribotyping. The genetic diversity of the strains was related to the different geoclimatic isolation sites, type of oily sludge, and age of contamination of the sites. These results indicate that a combination of Rep-PCR fingerprinting and PCR-based ribotyping can be used as a high-resolution genomic fingerprinting method for elucidating intraspecies diversity among strains of P. citronellolis. 相似文献
93.
The Chediak-Higashi protein interacts with SNARE complex and signal transduction proteins 总被引:5,自引:0,他引:5
Tchernev VT Mansfield TA Giot L Kumar AM Nandabalan K Li Y Mishra VS Detter JC Rothberg JM Wallace MR Southwick FS Kingsmore SF 《Molecular medicine (Cambridge, Mass.)》2002,8(1):56-64
BACKGROUND:Chediak-Higashi syndrome (CHS) is an inherited immunodeficiency disease characterized by giant lysosomes and impaired leukocyte degranulation. CHS results from mutations in the lysosomal trafficking regulator (LYST) gene, which encodes a 425-kD cytoplasmic protein of unknown function. The goal of this study was to identify proteins that interact with LYST as a first step in understanding how LYST modulates lysosomal exocytosis. MATERIALS AND METHODS: Fourteen cDNA fragments, covering the entire coding domain of LYST, were used as baits to screen five human cDNA libraries by a yeast two-hybrid method, modified to allow screening in the activation and the binding domain, three selectable markers, and more stringent confirmation procedures. Five of the interactions were confirmed by an in vitro binding assay. RESULTS: Twenty-one proteins that interact with LYST were identified in yeast two-hybrid screens. Four interactions, confirmed directly, were with proteins important in vesicular transport and signal transduction (the SNARE-complex protein HRS, 14-3-3, and casein kinase II). CONCLUSIONS:On the basis of protein interactions, LYST appears to function as an adapter protein that may juxtapose proteins that mediate intracellular membrane fusion reactions. The pathologic manifestations observed in CHS patients and in mice with the homologous mutation beige suggest that understanding the role of LYST may be relevant to the treatment of not only CHS but also of diseases such as asthma, urticaria, and lupus, as well as to the molecular dissection of the CHS-associated cancer predisposition. 相似文献
94.
95.
Krishnan AV Moreno J Nonn L Malloy P Swami S Peng L Peehl DM Feldman D 《The Journal of steroid biochemistry and molecular biology》2007,103(3-5):694-702
Calcitriol, the hormonally active form of Vitamin D, inhibits the growth and development of many cancers through multiple mechanisms. Our recent research supports the contributory role of several new and diverse pathways that add to the mechanisms already established as playing a role in the actions of calcitriol to inhibit the development and progression of prostate cancer (PCa). Calcitriol increases the expression of insulin-like growth factor binding protein-3 (IGFBP-3), which plays a critical role in the inhibition of PCa cell growth by increasing the expression of the cell cycle inhibitor p21. Calcitriol inhibits the prostaglandin (PG) pathway by three actions: (i) the inhibition of the expression of cyclooxygenase-2 (COX-2), the enzyme that synthesizes PGs, (ii) the induction of the expression of 15-prostaglandin dehydrogenase (15-PGDH), the enzyme that inactivates PGs and (iii) decreasing the expression of EP and FP PG receptors that are essential for PG signaling. Since PGs have been shown to promote carcinogenesis and progression of multiple cancers, the inhibition of the PG pathway may add to the ability of calcitriol to prevent and inhibit PCa development and growth. The combination of calcitriol and non-steroidal anti-inflammatory drugs (NSAIDs) result in a synergistic inhibition of PCa cell growth and offers a potential therapeutic strategy. Mitogen activated protein kinase phosphatase 5 (MKP5) is a member of a family of phosphatases that are negative regulators of MAP kinases. Calcitriol induces MKP5 expression in prostate cells leading to the selective dephosphorylation and inactivation of the stress-activated kinase p38. Since p38 activation is pro-carcinogenic and is a mediator of inflammation, this calcitriol action, especially coupled with the inhibition of the PG pathway, contributes to the chemopreventive activity of calcitriol in PCa. Mullerian Inhibiting Substance (MIS) has been evaluated for its inhibitory effects in cancers of the reproductive tissues and is in development as an anti-cancer drug. Calcitriol induces MIS expression in prostate cells revealing yet another mechanism contributing to the anti-cancer activity of calcitriol in PCa. Thus, we conclude that calcitriol regulates myriad pathways that contribute to the potential chemopreventive and therapeutic utility of calcitriol in PCa. 相似文献
96.
97.
Anup S. Deshpande Sellappan Krishnan Malapati K. Janarthanam Bruce R. Maslin 《Nordic Journal of Botany》2019,37(4)
An annotated checklist of Senegalia Raf. and Vachellia Wight & Arn. taxa for the Indian subcontinent is presented, following the fragmentation and retypification of the former broadly defined genus Acacia Mill. The countries encompassed by this study include Bangladesh, Bhutan, India, Maldives, Nepal, Pakistan and Sri Lanka. All indigenous species (and a few introductions) in this region previously referred to Acacia belong to Senegalia and Vachellia. All Acacia s.s. taxa are introduced (principally from Australia) and are not included in the study. There are 22 species of Senegalia (21 indigenous, 1 introduced; representing 23 taxa) and 21 species of Vachellia (12 indigenous, 9 introduced; representing 27 taxa) currently recognized for the subcontinent. The largest country, India, has most species. This checklist complements that which was recently provided for these genera in southeast Asia and China. Two names formerly recorded for the Indian subcontinent are excluded, namely, Senegalia intsia (L.) Maslin is a nomen confusum and Acacia pennata subsp. hainanensis (Hayata) I. C. Nielsen is now known to be restricted to southern China and Vietnam. Acacia eriantha Desv. is an unresolved name. The following new combinations are made herein: Senegalia tanjorensis (Ragup., Thoth. & A.Mahad.) A.S.Deshpande & Maslin, Vachellia campbellii (Arn.) A.S.Deshp., & Maslin and V. pseudowightii (Thoth.) A.S.Deshpande & Maslin. A lectotype has been selected for Acacia pennata var. canescens Graham ex Kurz (= Senegalia pennata (L.) Maslin). 相似文献
98.
99.
Sudarslal S Majumdar S Ramasamy P Dhawan R Pal PP Ramaswami M Lala AK Sikdar SK Sarma SP Krishnan KS Balaram P 《FEBS letters》2003,553(1-2):209-212
A 26 residue peptide (Am 2766) with the sequence CKQAGESCDIFSQNCCVG-TCAFICIE-NH(2) has been isolated and purified from the venom of the molluscivorous snail, Conus amadis, collected off the southeastern coast of India. Chemical modification and mass spectrometric studies establish that Am 2766 has three disulfide bridges. C-terminal amidation has been demonstrated by mass measurements on the C-terminal fragments obtained by proteolysis. Sequence alignments establish that Am 2766 belongs to the delta-conotoxin family. Am 2766 inhibits the decay of the sodium current in brain rNav1.2a voltage-gated Na(+) channel, stably expressed in Chinese hamster ovary cells. Unlike delta-conotoxins have previously been isolated from molluscivorous snails, Am 2766 inhibits inactivation of mammalian sodium channels. 相似文献
100.