全文获取类型
收费全文 | 612篇 |
免费 | 1篇 |
国内免费 | 3篇 |
专业分类
系统科学 | 4篇 |
现状及发展 | 388篇 |
研究方法 | 68篇 |
综合类 | 153篇 |
自然研究 | 3篇 |
出版年
2018年 | 4篇 |
2017年 | 4篇 |
2016年 | 6篇 |
2015年 | 3篇 |
2013年 | 12篇 |
2012年 | 23篇 |
2011年 | 30篇 |
2010年 | 14篇 |
2009年 | 3篇 |
2008年 | 26篇 |
2007年 | 20篇 |
2006年 | 26篇 |
2005年 | 19篇 |
2004年 | 16篇 |
2003年 | 17篇 |
2002年 | 10篇 |
2001年 | 7篇 |
2000年 | 9篇 |
1999年 | 11篇 |
1998年 | 8篇 |
1996年 | 4篇 |
1992年 | 11篇 |
1991年 | 3篇 |
1989年 | 6篇 |
1988年 | 4篇 |
1986年 | 8篇 |
1985年 | 4篇 |
1984年 | 7篇 |
1983年 | 6篇 |
1982年 | 3篇 |
1981年 | 3篇 |
1980年 | 12篇 |
1979年 | 22篇 |
1978年 | 19篇 |
1977年 | 18篇 |
1976年 | 13篇 |
1975年 | 9篇 |
1974年 | 13篇 |
1973年 | 18篇 |
1972年 | 18篇 |
1971年 | 21篇 |
1970年 | 31篇 |
1969年 | 20篇 |
1968年 | 17篇 |
1967年 | 15篇 |
1966年 | 16篇 |
1965年 | 4篇 |
1962年 | 2篇 |
1954年 | 2篇 |
1947年 | 2篇 |
排序方式: 共有616条查询结果,搜索用时 453 毫秒
121.
F. Hernmen W. Mahana P. Jollès A. Paraf 《Cellular and molecular life sciences : CMLS》1992,48(1):79-84
Embden goose (GEWL) and Barbary duck (DEWL) egg white lysozymes possess different amino acid sequences corresponding to the g-type and c-type, respectively. GEWL was shown to be a better immunogen than DEWL in both rabbits and mice. The antigenicity of the two lysozymes was tested using different technique (i.e. indirect ELISA, inhibition tests and immunoabsorption experiments). Injection of either GEWL or DEWL into rabbits and mice induced both specific antibodies and cross-reacting antibodies. Moreover, anti-GEWL antibodies, in contrast to anti-DEWL antibodies, did not cross-react with hen egg white lysozyme (HEWL), a c-type lysozyme. While the structure of GEWL was not modified after binding to plastic, DEWL was denaturated, but it did keep some native epitopes. It was concluded that g-type and c-type lysozymes, which have different amino acid sequences, exhibit strong common antigenic properties. 相似文献
122.
Immunomodulating lipopeptides lauroyl-L-Ala-gamma-D-Glu-LL-A2pmNH2-Gly (RP 44.102) and lauroyl-L-Ala-gamma-D-Glu-LL-A2pmNH2 (RP 56.142) were found to protect mice against the hepatotoxicity of paracetamol, which is due to cytochrome P-450 dependent formation of toxic metabolites and radicals. In fact they decreased the amount of hepatic microsomal cytochrome P-450, and the level of CCl4-induced lipid peroxidation. In contrast lauroyl-L-Ala-gamma-D-Glu-DD-A2pmNH2 (RP 53.204), which only differs by the configuration of the two chiral carbons of A2pm (diaminopimelic acid) and is not an immunomodulating agent, failed to protect against poisoning by paracetamol and had no effect on the level of hepatic cytochrome P-450 or the microsomal CCl4-induced lipid peroxidation. This provides a clear connection between the immunostimulating properties of a compound and its effects on xenobiotic biotransformations. 相似文献
123.
求出一种4—导数量子引力的Feynman规则和W—S恒等式。其中引力子自由传播子和三点顶角与其它文献不同。 相似文献
124.
J. R. Lazutka V. Dedonytè R. K. Lekevičius 《Cellular and molecular life sciences : CMLS》1992,48(5):508-512
The effects of alcohol consumption, cigarette smoking and age on sister chromatid exchangen (SCE) frequency in human lymphocytes were assessed by means of multiple linear regression. An increase in SCE rates was associated with alcohol consumption (p=0.0001), smoking (p=0.0231), and, to a small extent (p=0.057), age. These three confounding factors explain 48% of the inter-personal variation in SCE rates among subjects studied.We are grateful to Dr D. Krapavickaité for performing, the statistical analysis, and to Mrs V. Navickiené for technical assistance. We also wish to thank Dr B. Lambert (Stockholm, Sweden) for his valuable suggestions. 相似文献
125.
Laura Pecci S. Duprè A. Antonucci D. Cavallini 《Cellular and molecular life sciences : CMLS》1980,36(8):910-911
Summary Pyridoxal-5-phosphate (PLP) reacts with -carboxyglutamic acid (Gla) to form a stable complex absorbing at 325 nm. It is suggested that a condensation occurs in which the formyl group of PLP reacts with the -amino group and the carbon atom of Gla to give a pyrrolidine derivative. 相似文献
126.
Elena Galfrè Lauretta Galeno Oscar Moran 《Cellular and molecular life sciences : CMLS》2012,69(21):3701-3713
Nucleotide binding domains (NBD1 and NBD2) of the cystic fibrosis transmembrane conductance regulator (CFTR), the defective protein in cystic fibrosis, are responsible for controlling the gating of the chloride channel and are the putative binding sites for several candidate drugs in the disease treatment. We studied the effects of the application of 2-pyrimidin-7,8-benzoflavone (PBF), a strong potentiator of the CFTR, on the properties of recombinant and equimolar NBD1/NBD2 mixture in solution. The results indicate that the potentiator induces significant conformational changes of the NBD1/NBD2 dimer in solution. The potentiator does not modify the ATP binding constant, but reduces the ATP hydrolysis activity of the NBD1/NBD2 mixture. The intrinsic fluorescence and the guanidinium denaturation measurements indicate that the potentiator induces different conformational changes on the NBD1/NBD2 mixture in the presence and absence of ATP. It was confirmed from small-angle X-ray scattering experiments that, in absence of ATP, the NBD1/NBD2 dimer was disrupted by the potentiator, but in the presence of 2?mM ATP, the two NBDs kept dimerised, and a major change in the size and the shape of the structure was observed. We propose that these conformational changes could modify the NBDs–intracellular loop interaction in a way that would facilitate the open state of the channel. 相似文献
127.
Most economic variables are released with a lag, making it difficult for policy‐makers to make an accurate assessment of current conditions. This paper explores whether observing Internet browsing habits can inform practitioners about aggregate consumer behavior in an emerging market. Using data on Google search queries, we introduce an index of online interest in automobile purchases in Chile and test whether it improves the fit and efficiency of nowcasting models for automobile sales. Despite relatively low rates of Internet usage among the population, we find that models incorporating our Google Trends Automotive Index outperform benchmark specifications in both in‐sample and out‐of‐sample nowcasts, provide substantial gains in information delivery times, and are better at identifying turning points in the sales data. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
128.
J. Dubail F. Kesteloot C. Deroanne P. Motte V. Lambert J.-M. Rakic C. Lapière B. Nusgens A. Colige 《Cellular and molecular life sciences : CMLS》2010,67(24):4213-4232
ADAMTS-2 is a metalloproteinase that plays a key role in the processing of fibrillar procollagen precursors into mature collagen
molecules by excising the amino-propeptide. We demonstrate that recombinant ADAMTS-2 is also able to reduce proliferation
of endothelial cells, and to induce their retraction and detachment from the substrate resulting in apoptosis. Dephosphorylation
of Erk1/2 and MLC largely precedes the ADAMTS-2 induced morphological alterations. In 3-D culture models, ADAMTS-2 strongly
reduced branching of capillary-like structures formed by endothelial cells and their long-term maintenance and inhibited vessels
formation in embryoid bodies (EB). Growth and vascularization of tumors formed in nude mice by HEK 293-EBNA cells expressing
ADAMTS-2 were drastically reduced. A similar anti-tumoral activity was observed when using cells expressing recombinant deleted
forms of ADAMTS-2, including catalytically inactive enzyme. Nucleolin, a nuclear protein also found to be associated with
the cell membrane, was identified as a potential receptor mediating the antiangiogenic properties of ADAMTS-2. 相似文献
129.
130.