全文获取类型
收费全文 | 204篇 |
免费 | 11篇 |
国内免费 | 11篇 |
专业分类
系统科学 | 9篇 |
现状及发展 | 95篇 |
研究方法 | 17篇 |
综合类 | 100篇 |
自然研究 | 5篇 |
出版年
2022年 | 3篇 |
2021年 | 3篇 |
2019年 | 3篇 |
2018年 | 9篇 |
2017年 | 5篇 |
2016年 | 8篇 |
2015年 | 2篇 |
2014年 | 13篇 |
2013年 | 4篇 |
2012年 | 11篇 |
2011年 | 14篇 |
2010年 | 6篇 |
2009年 | 3篇 |
2008年 | 10篇 |
2007年 | 9篇 |
2006年 | 8篇 |
2005年 | 6篇 |
2004年 | 6篇 |
2003年 | 2篇 |
2002年 | 5篇 |
2000年 | 2篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1990年 | 3篇 |
1989年 | 3篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 5篇 |
1984年 | 2篇 |
1983年 | 7篇 |
1982年 | 2篇 |
1981年 | 5篇 |
1980年 | 4篇 |
1979年 | 11篇 |
1978年 | 10篇 |
1977年 | 3篇 |
1976年 | 2篇 |
1975年 | 4篇 |
1974年 | 2篇 |
1973年 | 3篇 |
1971年 | 1篇 |
1970年 | 2篇 |
1969年 | 2篇 |
1968年 | 5篇 |
1967年 | 3篇 |
1963年 | 1篇 |
1962年 | 2篇 |
1959年 | 1篇 |
1957年 | 1篇 |
排序方式: 共有226条查询结果,搜索用时 15 毫秒
211.
Summary In the present investigation, an attempt has been made to study the mating competitiveness and fertility of males as well as females ofDacus dorsalis Hendel (Diptera: Tephritidae) treated topically with thiotepa. In the mixed population, treated flies of either sex were found to be sexually more vigorous than untreated flies. However when the mating competitiveness of either sex was determined separately using various methods, treated males were found not to differ significantly in sexual competitiveness from untreated flies. Receptivity of treated and untreated females to males was also studied by the single choice method. Thiotepa-treated and untreated females were found to be equally receptive to males. 相似文献
212.
K. P. Srivastava R. K. Tiwari P. Kumar 《Cellular and molecular life sciences : CMLS》1977,33(1):98-99
Summary Sectioning the nerves innervating the prothoracic glands of the larva of the lemon-butterfly has no effect on the development and metamorphosis of the insect. The results are discussed in the light of the known facts.We wish to acknowledge the financial support from the Atomic Energy Commission, Bombay, and the working facilities provided by Prof. M. S. Kanungo, Head of the Department. 相似文献
213.
R. Kumar 《Cellular and molecular life sciences : CMLS》1976,32(7):880-881
Summary Haemolymph ofPalamnaeus bengalensis contains normally 12 and during moulting up to 15 free amino acids, being in maximal number at the end of ecdysis. Aminoacidaemia is most pronounced during the pharate stage. Tyrosine appeared for tanning of the cuticle. Taurine and methionine were not present.Acknowledgment. The author is thankful to Dr.S. C. Shrivastava for valuable guidance and State C.S.I.R. (U.P.) for funds. 相似文献
214.
D Kumar 《Experientia》1981,37(1):37-38
Autoradiographic studies using 3H-uridine in the salivary gland of adult Lygaeus sp. were carried out. The gland cell nuclei, particularly the multiple nucleoli, are the sites of incorporation of the label exhibiting RNA synthesis. The labelled molecules (RNA) are transported to the cell cytoplasm and then into the gland lumen in which no turnover of the radioactivity is observed. 相似文献
215.
H. Kumar V. C. Mercykutty R. M. Singh 《Cellular and molecular life sciences : CMLS》1985,41(12):1594-1595
Summary Two off-type plants, morphologically distinguishable from each other and from their respective sister euploid, were isolated in the M3 generation of pea interchange heterozygotes. Pollen sterility was very high, ranging from 63.0 to 90.0%. Cytologically one of them was tetrasomic (2n+2=16) and the other one was quadruple trisomic (2n+1+1+1+1=18). In the tetrasomic plant 1IV+6II was the most frequent (46.7%) chromosome configuration, while cells with 4III+3II were predominant (40.0% cells) in the quadruple trisomic plant.Financial assistance of C.S.I.R., New Delhi, India is acknowledged. 相似文献
216.
S. Ghosal D. K. Chakrabarti K. Biswas Y. Kumar 《Cellular and molecular life sciences : CMLS》1979,35(12):1633-1634
Summary Accumulation of mangiferin and degraded carotenoids, in response toFusarium moniliforme infection, has been suggested to be responsible for the malformation disease ofMangifera indica L. (Anacardiaceae).Acknowledgments. The authors are indebted to the University Grants Commission, New Delhi, for financial assistance to carry out this project. 相似文献
217.
Summary The neural tissue of the monkey pineal contains both acetyl and butyryl cholinesterases. Acetylcholinesterase was localized in the cisternae of the nuclear membrane, rough endoplasmic reticulum, on the plasma membrane of the neurones, and on the axolemma of both non-myelinated and myelinated fibres. The enzyme was not found in the axosomatic or axo-dendritic synapses. It is therefore suggested that the pineal neurones have a cholinergic function rather than a cholinoceptive one.This study was supported by the WHO. 相似文献
218.
Summary Seeds ofSolanum surattense Burm. f. collected from areas of Bhopal (India) affected by methylisocyanate gas showed chromosome aberrations in root cells, and growth retardation and chlorophyll mutation of seedlings, the frequencies of which varied from one locality to another. 相似文献
219.
R. K. Kumar 《Cellular and molecular life sciences : CMLS》1978,34(6):768-769
Summary Retrograde lymphatic permeation of the liver by a malignant neoplasm is an unusual phenomenon and has apparently not been reported with colonic carcinoma. This paper presents such a case; the features of the lesion are similar to those described for other primary sites.Acknowledgment. The author thanks the staff of the Department of Morbid Anatomy at St. Vincent's Hospital, Sydney, for their cooperation and assistance with this case. 相似文献
220.
Building on recent and growing evidence that geographic location influences information diffusion, this paper examines the relation between firm's location and the predictability of stock returns. We hypothesize that returns on a portfolio composed of firms located in central areas are more likely to follow a random walk than returns on a portfolio composed of firms located in remote areas. Using a battery of variance ratio tests, we find strong and robust support for our prediction. In particular, we show that the returns on a portfolio composed of the 500 largest urban firms follow a random walk; however, all variance ratio tests reject the random walk hypothesis for a portfolio that includes the 500 largest rural firms. Our results are robust to alternative definitions of firm's location and portfolio formation. 相似文献