全文获取类型
收费全文 | 7730篇 |
免费 | 679篇 |
国内免费 | 4篇 |
专业分类
8413篇 |
出版年
2023年 | 58篇 |
2022年 | 143篇 |
2021年 | 275篇 |
2020年 | 147篇 |
2019年 | 177篇 |
2018年 | 201篇 |
2017年 | 160篇 |
2016年 | 339篇 |
2015年 | 515篇 |
2014年 | 532篇 |
2013年 | 537篇 |
2012年 | 759篇 |
2011年 | 656篇 |
2010年 | 390篇 |
2009年 | 369篇 |
2008年 | 503篇 |
2007年 | 434篇 |
2006年 | 387篇 |
2005年 | 297篇 |
2004年 | 300篇 |
2003年 | 273篇 |
2002年 | 249篇 |
2001年 | 56篇 |
2000年 | 36篇 |
1999年 | 42篇 |
1998年 | 62篇 |
1997年 | 30篇 |
1996年 | 24篇 |
1995年 | 29篇 |
1994年 | 25篇 |
1993年 | 32篇 |
1992年 | 27篇 |
1991年 | 24篇 |
1990年 | 18篇 |
1989年 | 23篇 |
1988年 | 18篇 |
1987年 | 9篇 |
1986年 | 12篇 |
1985年 | 14篇 |
1984年 | 19篇 |
1983年 | 24篇 |
1982年 | 9篇 |
1981年 | 16篇 |
1980年 | 13篇 |
1979年 | 12篇 |
1978年 | 15篇 |
1977年 | 12篇 |
1976年 | 9篇 |
1975年 | 11篇 |
1974年 | 9篇 |
排序方式: 共有8413条查询结果,搜索用时 15 毫秒
1.
Julia I. Gavrilyuk Ulrich Wuellner Syed Salahuddin Rajib K. Goswami Subhash C. Sinha Carlos F. Barbas 《Bioorganic & medicinal chemistry letters》2009,19(14):3716-3720
Irreversible chemical programming of monoclonal aldolase antibody (mAb) 38C2 has been accomplished with β-lactam equipped mono- and bifunctional targeting modules, including a cyclic-RGD peptide linked to either the peptide (d-Lys6)-LHRH or another cyclic RGD unit and a small-molecule integrin inhibitor SCS-873 conjugated to (d-Lys6)LHRH. We also prepared monofunctional targeting modules containing either cyclic RGD or (d-Lys6)-LHRH peptides. Binding of the chemically programmed antibodies to integrin receptors α(v)β(3) and α(v)β(5) and to the luteinizing hormone releasing hormone receptor were evaluated. The bifunctional and bivalent c-RGD/LHRH and SCS-783/LHRH, the monofunctional and tetravalent c-RGD/c-RGD, and the monofunctional bivalent c-RGD chemically programmed antibodies bound specifically to the isolated integrin receptor proteins as well as to integrins expressed on human melanoma M-21 cells. c-RGD/LHRH, SCS-783/LHRH, and LHRH chemically programmed antibodies bound specifically to the LHRH receptors expressed on human ovarian cancer cells. This approach provides an efficient, versatile, and economically viable route to high-valency therapeutic antibodies that target defined combinations of specific receptors. Additionally, this approach should be applicable to chemically programmed vaccines. 相似文献
2.
3.
4.
The biosynthesis of glyantrypine from radiolabelled amino acid precursors has been shown experimentally to involve anthranilic acid, tryptophan and glycine. Low values for percentage incorporation of radiolabel into glyantrypine were partly influenced by a complex array of other novel alkaloids shown by the radiolabelling experiments to be related to glyantrypine. Interpretation of radiolabel incorporation from [14C-carboxyl]-anthranilic acid into microbial metabolites seen to contain an anthranilyl moiety in various biosynthetic arrangements is discussed. The possibility of diversion of anthranilic acid from the kynurenine pathway to glyantrypine biosynthesis is recognised. 相似文献
5.
6.
Specific and nonspecific T-cell invasion into cerebrospinal fluid has been investigated in the nonfatal viral meningoencephalitis induced by intracerebral inoculation of mice with vaccinia virus. At the peak of the inflammatory process on Day 7 approximately 5 to 10% of the Lyt 2+ T cells present are apparently specific for vaccinia virus. Concurrently, in mice primed previously with influenza virus, 0.5 to 1.0% of the appropriate T-cell set located in cerebrospinal fluid is reactive to influenza-infected target cells. This vaccinia virus-induced inflammatory exudate may thus contain as many as 500 influenza-immune memory T cells. These findings are discussed from the aspect that such nonspecific T-cell invasion into the central nervous system during aseptic viral meningitis could result in exposure of potentially brain-reactive T cells to central nervous system components. 相似文献
7.
The enzymic estimation of glutamate and glutamine 总被引:2,自引:1,他引:1
A method of estimating glutamic acid is described, based on its dehydrogenation by glutamate dehydrogenase coupled, by means of N-methylphenazine methosulphate, to the reduction of tetrazolium salts. The method is suitable for the estimation of 0-0.3mumole of glutamic acid. The response is linear, but not stoicheiometric: possible reasons for this are discussed. If suitable precautions are taken, the use of a partially purified preparation of glutaminase makes it possible to estimate glutamine also. 相似文献
8.
9.
In the present study, the bombesin-induced changes in cytosolic free Ca2+ ([Ca2+]i) were investigated in single Fura-2 loaded SV-40 transformed hamster β-cells (HIT). Bombesin (50–500 pM) caused frequency-modulated repetitive Ca2+ transients. The average frequency of the Ca2+ transients induced by bombesin (200 pM) was 0.58 ± 0.02 min−1 (n = 121 cells). High concentrations of bombesin (≥ 2 nM) triggered a large initial Ca2+ transient followed by a sustained plateau or by a decrease to basal levels. In Ca2+- free medium, bombesin caused only one or two Ca2+ transients and withdrawal of extracellular Ca2+ abolished the Ca2+ transients. The voltage-dependent Ca2+ channel (VDCC) blockers, verapamil (50 μM) and nifedipine (10 μM), reduced amplitude and frequency of the Ca2+ transients and stopped the Ca2+ transients in some cells. Thapsigargin caused a sustained rise in [Ca2+]i) in the presence of extracellular Ca2+ while in its absence the rise in [Ca2+]i) was transient. Verapamil (50 μM) inhibited the thapsigargin-induced increase in [Ca2+], by about 50%. Depletion of intracellular Ca2+ stores by repetitive stimulation with increasing concentrations of bombesin or thapsigargin in Ca2+-free medium caused an agonist-independent increase in [Ca2+]i) when extracellular Ca2+ was restored, which was larger than in control cells that had been incubated in Ca2+-free medium for the same period of time. This rise in [Ca2+]i and the thapsigargin-induced increase in [Ca2+]i) were only partly inhibited by VDCC-blockers. Thus, depletion of the agonist-sensitive Ca2+ pool enhances Ca2+ influx through VDCC and voltage-independent Ca2+ channels (VICC). In conclusion, the bombesin-induced Ca2+ response in single HIT cells is periodic in nature with frequency-modulated repetitive Ca2+ transients. Intracellular Ca2+ is mobilized during each Ca2+ transient, but Ca2+ influx through VDCC and VICC is required for maintaining the sustained nature of the Ca2+ response. Ca2+ influx in whole or part is activated by a capacitative Ca2+ entry mechanism. 相似文献
10.