首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   1004篇
  免费   56篇
  1060篇
  2021年   11篇
  2020年   5篇
  2019年   8篇
  2018年   11篇
  2017年   8篇
  2016年   12篇
  2015年   24篇
  2014年   28篇
  2013年   41篇
  2012年   52篇
  2011年   57篇
  2010年   37篇
  2009年   29篇
  2008年   77篇
  2007年   75篇
  2006年   100篇
  2005年   83篇
  2004年   69篇
  2003年   72篇
  2002年   67篇
  2001年   17篇
  2000年   12篇
  1999年   11篇
  1998年   5篇
  1997年   8篇
  1996年   5篇
  1995年   4篇
  1994年   8篇
  1991年   11篇
  1990年   12篇
  1989年   6篇
  1988年   6篇
  1987年   5篇
  1986年   3篇
  1985年   8篇
  1984年   5篇
  1983年   5篇
  1981年   5篇
  1979年   5篇
  1978年   3篇
  1975年   8篇
  1974年   5篇
  1973年   6篇
  1972年   3篇
  1971年   3篇
  1970年   2篇
  1969年   3篇
  1968年   4篇
  1967年   2篇
  1966年   3篇
排序方式: 共有1060条查询结果,搜索用时 15 毫秒
1.
When the F1-ATPase from the thermophilic bacterium, PS3, was inactivated by 90% with 7-chloro-4-nitro[14C]benzofurazan ([14C]Nbf-Cl) at pH 7.3 and then gel-filtered, 1.25 mols of [14C]Nbf-O-Tyr and less than 0.1 mol of Nbf-N-Lys were formed per mol of enzyme. After adjusting the pH of the gel-filtered, modified enzyme to 9.0 and incubating it for 14 hrs. at 23 degrees C to promote O----N migration, 0.68 mol of Nbf-N-Lys were formed per mol of enzyme while about 16% of the original activity reappeared. Isolation of the subunits after the O----N migration showed that 90% of the incorporated 14C was present in the beta subunit, which contained 0.21 mols of [14C]Nbf-N-Lys per mol. A tryptic peptide which contained the majority of the 14C incorporated into the beta subunit was isolated and subjected to automatic amino acid sequence analysis contained 38 residues. The amino acid sequence immediately around the lysine residue labeled with [14C]Nbf-, K*, was found to be: ...I-G-L-F-G-G-A-G-V-G-K*-T-V-L-I-G... .  相似文献   
2.
Summary Familial occurrence of 1/21 translocation in connection with trisomy 21 was described. The possibilities of inheritance of further chromosome rearrangements arising during the gametogenesis of persons with this translocation were considered.  相似文献   
3.
Winter rape ( Brassica napus L., var. olifera cv. Górczanski) seedlings were exposed to hardening conditions and the content and composition of free sterols as well as the ratio of free sterols to total phospholipids were determined. There was a reduction in free sterol content in the leaves at the most advanced stage of hardening. The ratio of free sterol to total phospholipids was significantly reduced by hardening due to a decrease in the level of the former and an increase in that of the latter compounds. There was a negative correlation between this ratio and the temperature at which half of the seedlings died. Thus, adaptation of membranes to temperature takes place also at the level of sterol-phospholipid interactions. Exposing seedlings already hardened to freezing temperatures caused injury higher than 50%, and brought about a drastic increase in the level of free sterols and an elevation in the ratio of free sterols to phospholipids. The results are discussed in terms of a possible role of the molecular architecture of membranes in surviving at subzero temperatures.  相似文献   
4.
Almost 100% of 7- to 10-day-old Hymenolepis diminuta became established when surgically transplanted from donor mice into the duodenum of naive recipient mice. Transplanted tapeworms survived 8-12 days, by which time they had survived much longer in total than they would have done in the donor. Mice previously immunized by a primary infection rejected transplants within 4 days. Sub-lethal irradiation (550 rad) delayed rejection by immune mice but such mice still rejected worms much more quickly than did naive mice. Surgery was shown to delay by 2-3 days the rejection of worms by naive mice, and the importance of circumventing surgery by administering the worms per os is emphasized. Prospects for reconstituting irradiated immune mice are considered vis-à-vis work with nematodes, and the differences which, on present knowledge, appear to exist between nematode and cestode rejection are briefly discussed.  相似文献   
5.
6.
The concept of a dangeardien is discussed in relation to the ascomycetous yeasts. In species of ascomycetous affinity the dangeardien may be expressed not only as the ascus, but also in the taxa showing an alternation of generation in the absence of an ascosporal state, as a site of reduction division. In such cases it is proposed to refer to the dangeardien as a meioconidiophore and to the externally delimited haplophase, as meioconidia. Taxa showing the formation of meioconidiophores are considered to represent perfect states.  相似文献   
7.
It has been found that the type strain of Torulopsis dattila constitutes a perfect state since it is characterized by the formation of asci which rupture at maturity liberating 1–4 smooth, spheroidal ascospores which tend to agglutinate. On the basis of its physiological properties this strain is considered to be representative of Kluyveromyces thermotolerans.  相似文献   
8.
Abstract

5-(β-D-Ribofuranosyl)nicotinamide (lie) and 6-(β-D-ribo-furanosyDpicolinamide (IId) and their corresponding o-isomers (III) were synthesized from ribonolactone. The C-nucleoside lie was further converted to its 5′-monophosphate Up which is isosteric to NMN Ip).  相似文献   
9.
10.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号