全文获取类型
收费全文 | 1568篇 |
免费 | 193篇 |
国内免费 | 1篇 |
出版年
2021年 | 43篇 |
2020年 | 19篇 |
2019年 | 22篇 |
2018年 | 29篇 |
2017年 | 18篇 |
2016年 | 42篇 |
2015年 | 55篇 |
2014年 | 60篇 |
2013年 | 79篇 |
2012年 | 78篇 |
2011年 | 96篇 |
2010年 | 51篇 |
2009年 | 42篇 |
2008年 | 57篇 |
2007年 | 76篇 |
2006年 | 71篇 |
2005年 | 50篇 |
2004年 | 51篇 |
2003年 | 55篇 |
2002年 | 50篇 |
2001年 | 38篇 |
2000年 | 34篇 |
1999年 | 36篇 |
1998年 | 17篇 |
1997年 | 19篇 |
1996年 | 26篇 |
1995年 | 18篇 |
1994年 | 16篇 |
1993年 | 16篇 |
1992年 | 25篇 |
1991年 | 16篇 |
1990年 | 20篇 |
1989年 | 20篇 |
1988年 | 18篇 |
1987年 | 25篇 |
1986年 | 20篇 |
1985年 | 26篇 |
1984年 | 16篇 |
1983年 | 19篇 |
1982年 | 22篇 |
1981年 | 22篇 |
1980年 | 11篇 |
1979年 | 17篇 |
1978年 | 22篇 |
1977年 | 20篇 |
1976年 | 12篇 |
1975年 | 21篇 |
1974年 | 13篇 |
1973年 | 17篇 |
1972年 | 18篇 |
排序方式: 共有1762条查询结果,搜索用时 766 毫秒
31.
32.
Detection of Lymphocytic Choriomeningitis Virus Antibody in Murine Sera by Immunofluorescence 下载免费PDF全文
An immunofluorescence technique developed for detection of antibody in murine sera to lymphocyitc choriomeningitis virus is described. 相似文献
33.
34.
A survey was carried out to determine for the first time the extent of transplantation from living donors in the United Kingdom and Republic of Ireland and the views of transplant surgeons regarding future developments. Questionnaires were sent to 32 transplant centres representing 18 health regions and covered their extent of experience of transplantation, sources of donors, ages of donors and recipients, outcome of transplantation, and views on expansion of living donor transplantation services. Replies received from 27 transplant centres representing 17 health regions gave data on more than 1200 transplants from living donors. Transplants from living donors accounted for 0-25% of the total experience of health regions. Two centres had abandoned living donor transplantation. Sixty per cent of transplant surgeons favoured expansion of the living donor programme to meet a shortage of kidneys from cadavers, and the remainder thought that existing programmes were optimal. Living donor transplantation promises to be an important factor in the future planning of health care resources. 相似文献
35.
L Varesio M Clayton E Blasi R Ruffman D Radzioch 《Journal of immunology (Baltimore, Md. : 1950)》1990,145(12):4265-4271
We have studied the effects of picolinic acid, a product of tryptophan degradation, on the activation of mouse peritoneal macrophages (M phi). Picolinic acid acts synergistically with IFN-gamma in activating M phi from C57BL/6 mice. Moreover, M phi from C3H/HeJ mice and C3H/HeN that do not become cytotoxic in response to IFN-gamma alone could be fully activated by exposure to picolinate plus IFN-gamma. These results indicate that picolinic acid is a potent costimulator of M phi activation that functions as a second signal. Inasmuch as we have previously demonstrated that the activation of cytotoxic M phi correlates with specific changes in ribosomal RNA (rRNA), we investigated whether picolinic acid could modify M phi RNA metabolism. Picolinic acid inhibited the synthesis of total M phi RNA, the accumulation of newly synthesized 28S rRNA, and augmented the steady state levels of rRNA precursors (pre-rRNA). These changes in RNA metabolism were similar to those previously described in murine M phi activated in vitro or in vivo to express tumoricidal activity. These results demonstrate that picolinic acid is a potent, biologic M phi second signal, suggest that the changes in rRNA are causally connected with the expression of tumoricidal activity, and suggest the existance of an autocrine effect mediated by picolinic acid. 相似文献
36.
Clayton E. Heyliger Talat J. Kheshgi Eric J. Murphy Sean Myers-Payne Friedhelm Schroeder 《Molecular and cellular biochemistry》1996,155(2):113-119
Relatively little is known of fatty acid specificity in cellular fatty acid uptake. In this study L-cells, a fibroblastic cell line with very low levels of endogenous cytosolic fatty acid binding protein, were used to examine the role of cis and trans unsaturation on fatty acid uptake. The fluorescent fatty acids, trans-parinaric acid and cis-parinaric acid, were used as analogs of straight-chain saturated, and kinked-chain unsaturated fatty acids, respectively, in order to evaluate the fatty acid specificity of the uptake system. Parinaric acid is poorly metabolizable; greater than 97% was unesterified while 3H-oleic acid was almost totally metabolized after 30 min uptake. Cis- and trans-parinaric acid uptake was saturable and dependent on the concentration of fatty acid. However, the initial rate and maximal amount of trans-parinaric acid taken up by the L-cells was greater than for cis-parinaric acid under the same conditions. The affinity of L-cell uptake for trans-parinaric acid (Km = 0.12 uM) was 35-fold higher than that for cis-parinaric acid (Km = 4.17 uM) . Based on competition studies with oleic and stearic acids, it was concluded that the cis- and trans-parinaric acid were taken up by the same L-cell fatty acid uptake system. The results suggest that the L-cell fatty acid uptake system has selectivity for straight chain rather than kinked chain unsaturated fatty acids.Abbreviations Cis-parinaric acid
9Z, 11E, 13E, 15Z-octatetraenoic acid
- trans-parinaric acid
9E, I IE, 13E, 15E-octatetraenoic acid
- EGTA
ethylene glycol-bis(beta-amlno-ethyl ether) N,N,N,N-tetratacetic acid
- BSA
bovine serum albumin
- PBS
phosphate buffered saline 相似文献
37.
38.
39.
Nienow AW Langheinrich C Stevenson NC Emery AN Clayton TM Slater NK 《Cytotechnology》1996,22(1-3):87-94
Because of concern for cell damage, very low agitation energy inputs have been used in industrial animal cell bioreactors, typical values being two orders of magnitude less than those found in bacterial fermentations. Aeration rates are also very small. As a result, such bioreactors might be both poorly mixed and also unable to provide the higher oxygen up-take rates demanded by more intensive operation. This paper reports experimental studies both of K
L
a and of mixing (via pH measurements) in bioreactors up to 8 m3 at Wellcome and of scaled down models of such reactors at Birmingham. Alongside these physical measurements, sensitivity of certain cell lines to continuously controlled dO2 has been studied and the oxygen up-take rates measured in representative growth conditions. An analysis of characteristic times and mixing theory, together with other recent work showing that more vigorous agitation and aeration can be used especially in the presence of Pluronic F-68, indicates ways of improving their performance. pH gradients offer a special challenge. 相似文献
40.
陈清轩 《基因组蛋白质组与生物信息学报(英文版)》1995,(1)
DetectionandAnalysisofanEstrous-associatedOviductalGlycoproteinDNAFragmentfromPrimatesbyPCR¥CHENQing-xuan(陈清轩);ClaytonE.Walto... 相似文献