全文获取类型
收费全文 | 1124篇 |
免费 | 106篇 |
国内免费 | 2篇 |
出版年
2022年 | 9篇 |
2021年 | 27篇 |
2020年 | 9篇 |
2019年 | 8篇 |
2018年 | 9篇 |
2017年 | 12篇 |
2016年 | 22篇 |
2015年 | 33篇 |
2014年 | 41篇 |
2013年 | 57篇 |
2012年 | 69篇 |
2011年 | 60篇 |
2010年 | 38篇 |
2009年 | 31篇 |
2008年 | 43篇 |
2007年 | 52篇 |
2006年 | 29篇 |
2005年 | 42篇 |
2004年 | 24篇 |
2003年 | 39篇 |
2002年 | 23篇 |
2001年 | 31篇 |
2000年 | 44篇 |
1999年 | 49篇 |
1998年 | 29篇 |
1997年 | 32篇 |
1996年 | 15篇 |
1995年 | 21篇 |
1994年 | 23篇 |
1993年 | 13篇 |
1992年 | 16篇 |
1991年 | 16篇 |
1990年 | 25篇 |
1989年 | 21篇 |
1988年 | 17篇 |
1987年 | 14篇 |
1986年 | 7篇 |
1985年 | 6篇 |
1984年 | 10篇 |
1983年 | 16篇 |
1982年 | 11篇 |
1980年 | 6篇 |
1979年 | 11篇 |
1976年 | 13篇 |
1975年 | 8篇 |
1974年 | 13篇 |
1973年 | 6篇 |
1972年 | 6篇 |
1971年 | 7篇 |
1969年 | 5篇 |
排序方式: 共有1232条查询结果,搜索用时 31 毫秒
71.
72.
73.
We describe the construction and quality analysis of six cDNA libraries from the liver, ovary, testis, brain, spleen and muscle tissues of adult Atlantic salmon. The cDNA libraries were then screened with total cDNA probes to catalogue clones representing the abundant and rare mRNA populations in each tissue. Subsequently, the 5'-terminal DNA sequences of 1152 cDNA clones, composed of 96 clones from each of the abundant and rare mRNA populations in the six tissues, were determined. Bioinformatic analysis revealed that 510 (50%) of the salmon expressed sequence tags (ESTs) of sufficient length showed significant homology to previously identified genes from salmonid and other species, while 517 (50%) of salmon ESTs were unidentified or novel. After accounting for multi-EST redundancy, the 510 identified ESTs provided DNA sequence markers for 178 salmon genes which are listed in terms of tissue of origin and mRNA abundance class. 相似文献
74.
Stone PJ O'Callaghan KJ Davey MR Cocking EC 《Molecular plant-microbe interactions : MPMI》2001,14(1):93-97
Improved conditions were used for the aseptic growth of Arabidopsis thaliana to investigate whether xylem colonization of A. thaliana by Azorhizobium caulinodans ORS571 might occur. When seedlings were inoculated with ORS571 (pXLGD4) tagged with the lacZ reporter gene, nearly all of the plants showed blue regions of ORS571 colonization at lateral root cracks (LRC). The flavonoids naringenin and liquiritigenin significantly stimulated colonization of LRC by ORS571. Blue bands of ORS571 (pXLGD4) bacteria were observed histochemically in the xylem of intact roots of inoculated plants. Detailed microscopic analysis of sections of primary and lateral roots from inoculated A. thaliana confirmed xylem colonization. Xylem colonization also occurred with an ORS571 nodC mutant deficient in nodulation factors. There was no significant difference in the percentage of plants with xylem colonization or in the mean length of xylem colonized per plant between plants inoculated with either ORS571 (pXLGD4) or ORS571::nodC (pXLGD4), with or without naringenin. 相似文献
75.
Jolanda?HM?van Bilsen Josée?PA?Wagenaar-Hilbers Maarten?JF?van der Cammen Mariska?EA?van Dijk Willem?van Eden Marca?HM?WaubenEmail author 《Arthritis research & therapy》2002,4(4):R2
We have recently found that matrix metalloproteinases (MMPs) are targets for T-cell and B-cell reactivity in experimental
arthritis. In the present article, we investigate whether modulation of MMP-specific T-cell responses could influence the
course of adjuvant arthritis (AA). Lewis rats were treated nasally with MMP peptides prior to or after AA induction. Administration
of the MMP-10 or the MMP-16 peptide prior to AA induction reduced the arthritic symptoms. In contrast, administration of the
MMP-10 peptide after AA induction aggravated the arthritic symptoms. The present study shows the possible usefulness of MMP
peptides for immunotherapy. However, a clear understanding of proper timing of peptide administration is crucial for the development
of such therapies. 相似文献
76.
Salinity tolerance and antioxidant status in cotton cultures 总被引:10,自引:0,他引:10
Garratt LC Janagoudar BS Lowe KC Anthony P Power JB Davey MR 《Free radical biology & medicine》2002,33(4):502-511
This investigation focuses upon cell growth and antioxidant status in cultured cells of cotton (Gossypium herbaceum) cvs. Dhumad (salt-tolerant, TOL), H-14 (medium salt-tolerant, MED), and RAhs-2 (salt-sensitive, SEN) exposed to saline stress (50-200 mM NaCl). Mean (+/- SEM) callus fresh weight (f.wt.) and dry weight (d.wt.) gains were significantly (p <.05) greater on Murashige and Skoog (MS) [1]-based medium with 50 mM NaCl for the TOL cv. (62% and 16%, respectively) over NaCl-free controls (2020 +/- 45 and 166 +/- 4 mg, respectively); comparable differences were not observed for the MED cv. A significant (p <.05) decrease in mean f.wt. occurred with the SEN cv. exposed to 50 mM NaCl. For all cvs., there were (p <.05) reductions in mean f.wts. in medium with >or=100 mM NaCl. At 200 mM NaCl, mean f.wt. decreases were 52% (TOL), 89% (MED), and 91% (SEN), respectively. A strong correlation existed between antioxidant status and growth of cells with NaCl. Superoxide dismutase and glutathione reductase activities increased with increasing salinity in the TOL cv. to maximum values of 26.3 +/- 1.1 U mg(-1) protein and 1.05 +/- 0.01 AB(340 nm) min(-1) mg(-1) protein, respectively, at 150 mM NaCl; for the MED and SEN cvs., there were no changes in activities of these enzymes between control and salt treatments. Catalase activity decreased progressively with increasing salt concentration in all cvs. except for SEN with 100 mM NaCl, where mean catalase activity (1.75 +/- 0.04 AB(240 nm) min(-1) mg(-1) protein) was greater (p <.05) than control (1.13 +/- 0.08). Overall, cultured cotton cells provide an experimental system for investigating the role of antioxidants in salt tolerance at the cellular level. 相似文献
77.
78.
Richard Scott Christopher Clark Ann Mathews Sarah Yallop Michael R. Davey Paul Lazzeri Effie Mutasa-Göttgens 《Molecular breeding : new strategies in plant improvement》2003,11(2):121-125
Increased public concern and strict statutory regulations relating tothe generation and exploitation of genetically modified organisms, make itimperative to track accurately individual plants through DNA transformationprogrammes. The ability to rapidly retrieve information associated withspecifictransgenic events and to provide accurate reports on demand is an increasinglyimportant feature for public research laboratories. Transgenic Plant Monitor(TPM) has been developed as a database structured to allow efficient recording,monitoring and analysis of the extensive and complex data generated in planttissue culture and transformation experiments. TPM is built upon the widelyavailable Microsoft Access database engine and can be readily adoptedand/or adapted by other users. The key features and the utility of TPM as aresearch tool are discussed in this article. 相似文献
79.
Kenneth?C.?LoweEmail author Paul?Anthony J.?Brian?Power Michael?R.?Davey 《In vitro cellular & developmental biology. Plant》2003,39(6):557-566
Summary The composition of the gaseous environment within tissue culture vessels is a critical factor in determining in vitro plant growth and morphogenic responsiveness. Consequently, the provision of an adequate and sustainable oxygen supply for
cultured plant cells (including isolated protoplasts), tissues and organs is a crucial prerequisite for optimization and regulation
of such cultural responses. During the past decade, research has focused on improving growth and development using artificial
gas carriers based on inert perfluorocarbon (PFC) liquids and hemoglobin (Hb) solution. Supplementation of culture media with
such artificial oxygen carriers has demonstrated beneficial effects of increased and sustainable cellular mitotic division
and subsequent biomass production in a diverse range of plant species, during both short- and longer-term culture. Studies
have targeted systems where oxygen availability is actually or potentially a major growth-limiting factor. Undoubtedly, gas
carrier-facilitated improvements in regulating the supply of respiratory gases to cultured cells, tissues and organs will
have increasingly important biotechnological and practical implications in the context of plant micropropagation, somatic
hybridization, transgenic plant production, and secondary product biosynthesis. 相似文献
80.
Tanaka M Cohn MJ Ashby P Davey M Martin P Tickle C 《Development (Cambridge, England)》2000,127(18):4011-4021
A central feature of the tetrapod body plan is that two pairs of limbs develop at specific positions along the head-to-tail axis. However, the potential to form limbs in chick embryos is more widespread. This could have implications for understanding the basis of limb abnormalities. Here we extend the analysis to mouse embryos and examine systematically the potential of tissues in different regions outside the limbs to contribute to limb structures. We show that the ability of ectoderm to form an apical ridge in response to FGF4 in both mouse and chick embryos exists throughout the flank as does ability of mesenchyme to provide a polarizing region signal. In addition, neck tissue has weak polarizing activity. We show, in chick embryos, that polarizing activity of tissues correlates with the ability either to express Shh or to induce Shh expression. We also show that cells from chick tail can give rise to limb structures. Taken together these observations suggest that naturally occurring polydactyly could involve recruitment of cells from regions adjacent to the limb buds. We show that cells from neck, flank and tail can migrate into limb buds in response to FGF4, which mimics extension of the apical ectodermal ridge. Furthermore, when we apply simultaneously a polarizing signal and a limb induction signal to early chick flank, this leads to limb duplications. 相似文献