全文获取类型
收费全文 | 241篇 |
免费 | 6篇 |
国内免费 | 4篇 |
出版年
2023年 | 2篇 |
2021年 | 2篇 |
2020年 | 2篇 |
2019年 | 4篇 |
2018年 | 4篇 |
2017年 | 2篇 |
2016年 | 1篇 |
2015年 | 1篇 |
2014年 | 5篇 |
2013年 | 8篇 |
2012年 | 4篇 |
2011年 | 7篇 |
2010年 | 5篇 |
2009年 | 5篇 |
2008年 | 8篇 |
2007年 | 7篇 |
2006年 | 9篇 |
2005年 | 7篇 |
2004年 | 5篇 |
2003年 | 11篇 |
2002年 | 8篇 |
2001年 | 2篇 |
2000年 | 3篇 |
1999年 | 4篇 |
1998年 | 3篇 |
1997年 | 4篇 |
1996年 | 3篇 |
1995年 | 3篇 |
1994年 | 6篇 |
1993年 | 2篇 |
1992年 | 3篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 5篇 |
1984年 | 14篇 |
1983年 | 6篇 |
1982年 | 12篇 |
1981年 | 10篇 |
1980年 | 6篇 |
1979年 | 8篇 |
1978年 | 8篇 |
1977年 | 5篇 |
1976年 | 6篇 |
1975年 | 7篇 |
1974年 | 9篇 |
1973年 | 9篇 |
1972年 | 1篇 |
排序方式: 共有251条查询结果,搜索用时 15 毫秒
1.
Pyrroline-5-carboxylate reductase, which required reduced pyridine nucleotide and Δ′-pyrroline-5-carboxylate for proline synthesis, was isolated from pumpkin cotyledons. The enzyme was found in the soluble fraction and had a 4.5-fold greater activity with NADH than NADPH. The enzyme was inhibited by NH2OH, NADP, ATP and slightly by proline. Glutathione or pyridoxal-5-phosphate had little effect on enzyme activity. The enzyme had a pH optimum between 7·0 and 7·6 and was not inhibited by high concentrations of NADH or Δ′-pyrroline-5-carboxylate. 相似文献
2.
Four new species ofCayaponia are described and illustrated: three from Brazil (C. cogniauxiana, C. nitida andC. rugosa) and one from Brazil and Bolivia (C. ferruginea). 相似文献
3.
Charles D. Howes 《Phytochemistry》1974,13(8):1469-1471
Nicotine inhibits carotenoid cyclization in greening cucurbit cotyledons resulting in the accumulation of acyclic and monocyclic carotenes. Chlorophyll synthesis is also inhibited by the alkaloid. 相似文献
4.
During germination a marked increase in both soluble and particulate ornthine transaminase occurs in pumpkin cotyledons. Both enzymes had a pH optimum of 8.3 and a requirement for ornthine and α-ketoglutarate. Other keto acids or amino donors showed little activity. The enzymes required an active sulphydryl group for maximum activity. Exogenous pyridoxal phosphate was not required, but hydroxylamine inhibited the reaction and added pyridoxal phosphate overcame this inhibition. Proline inhibited the reaction and may play a role in the fate of ornithine in pumpkin cotyledons. 相似文献
5.
《Journal of molecular recognition : JMR》2017,30(2)
Three isolectins denoted hereforth MBaL‐30, MBaL‐60, and MBaL‐80 were isolated from seeds extract of Momordica balsamina by 30%, 60%, and 80% ammonium sulfate saturations, respectively. The native molecular weights of these lectins, as judged by gel filtration, were 108, 56, and 160 kDa, respectively. On SDS‐PAGE, under reduced condition, 27 kDa band was obtained for all isolectins. The lectins hemagglutinating activities were variably inhibited by d ‐galactose (minimum inhibitory concentrations = 12.5mM, 50mM, and 0.391mM, respectively). MBaL‐30 and ‐60 could agglutinate all human blood types with slight preference for the A and O blood groups, whereas MBaL‐80 did not agglutinate B and AB blood types. The 3 isolectins were purified from crude seeds extract, collectively, in a single step on the affinity matrix Lactamyl‐Seralose 4B; this purified lectin fraction, which contains all isolectins, is termed MBaL. The N‐terminal of MBaL till the 25th amino acid was NLSLSELDFSADTYKSFIKNLRKQL, which shares 88% sequence identity with Momordica charantia lectin type‐2 ribosomal inactivating protein from Momordica charantia and 50% with momordin II from Momordica balsamina . MBaL retained 100% activity at up to 50°C for 30 minutes. MBaL‐30 and MBaL‐60 exhibited maximum activities in the pH range between 4 and 8, while MBaL‐80 was showing maximum activity in the pH range between 3 and 5. Treatment of MBaL‐30 and MBaL‐60 with EDTA completely abolished their hemagglutinating activities. Addition of Zn and Fe ions to the ethylenediaminetetraacetic acid–treated MBaL‐30 and MBaL‐60 lectins did not only regained the loss of activity but also resulted in 200% to 300% increase in activity, respectively. MBaL‐30 and ‐60 agglutinated gram positive Listeria monocytogenes and Staphylococcus aureus, whereas MBaL‐30 could merely agglutinate Escherichia coli . None of these lectins could arrest bacterial growth. Addition of MBaL to cancer cell lines (Gastric cancer cell line (AGS) and Gastric cencer cell line (MKN45), Glioblastoma (ECV‐304), and Human urinary bladder cancer cell line (U87‐MG)) at varying concentrations did not cause statistically significant changes on cell growth and viability. 相似文献
6.
The immature fruits of domesticated Luffa acutangula (L.) Roxb. are a common vegetable in Asia and India. To learn more about
traditional cultivars, accessions were collected from southern Yunnan Province of China, northern Laos, and southeastern Nepal,
and assessed for various parameters of genetic diversity. The size and shape of the fruits and seeds varied considerably.
A form that we found cultivated only in Nepal bore clusters of small fruits that are produced by hermaphrodite flowers. Plants
produced male flowers first, and the first node to bear flowers varied from the second to the twenty-seventh. Twenty-nine
allozyme loci were assayed. Within L. acutangula one allozyme locus was polymorphic. Luffa acutangula andL. aegyptiaca are fixed for different alleles at nine loci, indicating that they are completely reproductively isolated from each other. 相似文献
7.
8.
Hui Song Qun-Feng Lou Xiang-Dong Luo Joseph N. Wolukau Wei-Ping Diao Chun-Tao Qian Jin-Feng Chen 《Plant Cell, Tissue and Organ Culture》2007,90(3):245-254
Six experiments (including pretreatment, embryonic callus induction media, preculture conditions, embryo induction media,
embryo germination media, and genotypic effects) were conducted to develop an efficient cucumber (Cucumis sativus L., 2n = 2x = 14) anther culture protocol. Pretreatment and embryo induction were key factors for successful anther culture. Suitable
temperature stress depended on the ecotype, i.e., cucumbers from cold areas responded well to cold shock whereas those from
temperate areas responded well to heat treatment. The best medium for embryonic callus induction was MS medium supplemented
with 4.44 μM BA, 2.26 μM 2, 4-D, 4.64 μM KIN, 3% sucrose and 0.8% agar. For embryo induction, MS medium supplemented with
0.54 μM NAA, 13.32 μM BA, 3% sucrose and 0.8% agar was optimal, and for embryo germination MS medium containing 2.22 μM BA,
6% sucrose and 1.2% agar was best. Using this protocol, we produced callus from 16 genotypes and regenerated plants from three
of 20 evaluated. Three embryos per anther and 42 DH per 45 anthers (93% success) were obtained for cv. Ningjia No. 1, which
was an improved result over a previous report. The origin of regenerants from microspores was determined by cytological, morphological
and AFLP analyses. 相似文献
9.
Terence Galliard Jennifer A. Matthew Michael J. Fishwick Anthony J. Wright 《Phytochemistry》1976,15(11):1647-1650
Homogenization of fresh tissue from cucumber fruits results in a loss of endogenous lipid catalysed by acyl hydrolase enzymes. Deacylation of lipids is not accompanied by accumulation of free fatty acids. The levels of both saturated (mainly palmitic) and polyunsaturated (linoleic and linolenic) fatty acids in the lipids are reduced. Losses of the major acyl lipid constituents of cucumber (triacylglycerols and phospholipids) are mainly responsible for the observed hydrolysis. Triacylglycerol acyl hydrolase (lipase), phospholipase D and polar lipid acyl hydrolase enzyme activities were demonstrated. It is suggested that hydrolytic attack on endogenous lipids is the initial event on disruption of cucumber tissue, in the formation of lipid degradation products, amongst which are the volatile carbonyl compounds responsible for the characteristic flavour of cucumber. 相似文献
10.