全文获取类型
收费全文 | 87413篇 |
免费 | 6430篇 |
国内免费 | 2283篇 |
出版年
2023年 | 738篇 |
2022年 | 3250篇 |
2021年 | 4490篇 |
2020年 | 3266篇 |
2019年 | 3855篇 |
2018年 | 2244篇 |
2017年 | 1635篇 |
2016年 | 1932篇 |
2015年 | 2633篇 |
2014年 | 2886篇 |
2013年 | 3314篇 |
2012年 | 3581篇 |
2011年 | 3259篇 |
2010年 | 2207篇 |
2009年 | 2181篇 |
2008年 | 2185篇 |
2007年 | 2009篇 |
2006年 | 1793篇 |
2005年 | 1534篇 |
2004年 | 2855篇 |
2003年 | 3172篇 |
2002年 | 3313篇 |
2001年 | 4171篇 |
2000年 | 2886篇 |
1999年 | 2535篇 |
1998年 | 1986篇 |
1997年 | 2313篇 |
1996年 | 1230篇 |
1995年 | 1267篇 |
1994年 | 1551篇 |
1993年 | 1410篇 |
1992年 | 1198篇 |
1991年 | 963篇 |
1990年 | 1071篇 |
1989年 | 771篇 |
1988年 | 798篇 |
1987年 | 714篇 |
1986年 | 608篇 |
1985年 | 705篇 |
1984年 | 601篇 |
1983年 | 514篇 |
1982年 | 360篇 |
1981年 | 368篇 |
1979年 | 416篇 |
1978年 | 507篇 |
1977年 | 451篇 |
1976年 | 394篇 |
1972年 | 447篇 |
1971年 | 512篇 |
1970年 | 620篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
HIF-1 expression in healing wounds: HIF-1alpha induction in primary inflammatory cells by TNF-alpha 总被引:12,自引:0,他引:12
2.
Patterns of Sleeping Site and Sleeping Tree Selection by Black-and-Gold Howler Monkeys (Alouatta caraya) in Northern Argentina 总被引:1,自引:0,他引:1
Brividoro Melina V. Kowalewski Martin M. Scarry Clara J. Oklander Luciana I. 《International journal of primatology》2019,40(3):374-392
International Journal of Primatology - The selection of sleeping sites and sleeping trees in nonhuman primates is related to social and ecological factors. We investigate the role of body... 相似文献
3.
ABSTRACT The phrase persistent vulnerability reflects the enduring relationship of the rural population in Ceará with a highly variable climate. Persistence underscores the historical and unyielding nature of this vulnerability. Yet contrary to once-catastrophic rates of mortality etched in a public consciousness, no one dies from severe droughts and few people flee them as in the past. Government relief and social transfers have become the institutionalized form of adaptation, giving way to the counterintuitive reality that drought stabilizes the food and income supply for poor people. We analyze how maladaptive risk reduction, which is embedded in clientilistic social relations, undermines resilience, and we examine pathways toward a more sustainable adaptive relationship. 相似文献
4.
5.
The reaction of oxygen with hemoglobin and the kinetic basis of the effect of salt on binding of oxygen 总被引:7,自引:0,他引:7
Q H Gibson 《The Journal of biological chemistry》1970,245(13):3285-3288
6.
7.
8.
9.
Bugreev D. V. Sinitsyna O. I. Buneva V. N. Nevinsky G. A. 《Russian Journal of Bioorganic Chemistry》2003,29(3):249-261
Data on the interaction of DNA type I topoisomerases from the murine and human placenta cells with specific and nonspecific oligonucleotides of various structures and lengths are summarized. The relative contributions of various contacts between the enzymes and DNA that have previously been detected by X-ray analysis to the total affinity of the topoisomerases for DNA substrates are estimated. Factors that determine the differences in the enzyme interactions with specific and nonspecific single- and double-stranded DNAs are revealed. The results of the X-ray analysis of human DNA topoisomerase I are interpreted taking into account data on the comprehensive thermodynamic and kinetic analysis of the enzyme interaction with the specific and nonspecific DNAs. 相似文献
10.
Yeqi Nian Jasper Iske Ryoichi Maenosono Koichiro Minami Timm Heinbokel Markus Quante Yang Liu Haruhito Azuma Jinrui Yang Reza Abdi Hao Zhou Abdallah Elkhal Stefan G. Tullius 《Aging cell》2021,20(2)
Age impacts alloimmunity. Effects of aging on T‐cell metabolism and the potential to interfere with immunosuppressants have not been explored yet. Here, we dissected metabolic pathways of CD4+ and CD8+ T cells in aging and offer novel immunosuppressive targets. Upon activation, CD4+ T cells from old mice failed to exhibit adequate metabolic reprogramming resulting into compromised metabolic pathways, including oxidative phosphorylation (OXPHOS) and glycolysis. Comparable results were also observed in elderly human patients. Although glutaminolysis remained the dominant and age‐independent source of mitochondria for activated CD4+ T cells, old but not young CD4+ T cells relied heavily on glutaminolysis. Treating young and old murine and human CD4+ T cells with 6‐diazo‐5‐oxo‐l‐norleucine (DON), a glutaminolysis inhibitor resulted in significantly reduced IFN‐γ production and compromised proliferative capacities specifically of old CD4+ T cells. Of translational relevance, old and young mice that had been transplanted with fully mismatched skin grafts and treated with DON demonstrated dampened Th1‐ and Th17‐driven alloimmune responses. Moreover, DON diminished cytokine production and proliferation of old CD4+ T cells in vivo leading to a significantly prolonged allograft survival specifically in old recipients. Graft prolongation in young animals, in contrast, was only achieved when DON was applied in combination with an inhibition of glycolysis (2‐deoxy‐d‐glucose, 2‐DG) and OXPHOS (metformin), two alternative metabolic pathways. Notably, metabolic treatment had not been linked to toxicities. Remarkably, immunosuppressive capacities of DON were specific to CD4+ T cells as adoptively transferred young CD4+ T cells prevented immunosuppressive capacities of DON on allograft survival in old recipients. Depletion of CD8+ T cells did not alter transplant outcomes in either young or old recipients. Taken together, our data introduce an age‐specific metabolic reprogramming of CD4+ T cells. Targeting those pathways offers novel and age‐specific approaches for immunosuppression. 相似文献