全文获取类型
收费全文 | 448831篇 |
免费 | 55670篇 |
国内免费 | 283篇 |
专业分类
504784篇 |
出版年
2018年 | 3821篇 |
2017年 | 3505篇 |
2016年 | 5457篇 |
2015年 | 8168篇 |
2014年 | 9153篇 |
2013年 | 12865篇 |
2012年 | 14839篇 |
2011年 | 14949篇 |
2010年 | 9869篇 |
2009年 | 9127篇 |
2008年 | 13045篇 |
2007年 | 13524篇 |
2006年 | 12224篇 |
2005年 | 12034篇 |
2004年 | 11802篇 |
2003年 | 11242篇 |
2002年 | 10748篇 |
2001年 | 21628篇 |
2000年 | 21754篇 |
1999年 | 17387篇 |
1998年 | 6214篇 |
1997年 | 6468篇 |
1996年 | 6295篇 |
1995年 | 5695篇 |
1994年 | 5748篇 |
1993年 | 5566篇 |
1992年 | 13645篇 |
1991年 | 12957篇 |
1990年 | 12639篇 |
1989年 | 12494篇 |
1988年 | 11157篇 |
1987年 | 10781篇 |
1986年 | 9868篇 |
1985年 | 9647篇 |
1984年 | 8180篇 |
1983年 | 7067篇 |
1982年 | 5519篇 |
1981年 | 5000篇 |
1980年 | 4649篇 |
1979年 | 7682篇 |
1978年 | 5914篇 |
1977年 | 5424篇 |
1976年 | 5061篇 |
1975年 | 5362篇 |
1974年 | 5806篇 |
1973年 | 5655篇 |
1972年 | 5099篇 |
1971年 | 4726篇 |
1970年 | 3920篇 |
1969年 | 3850篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
931.
A kinin-directed monoclonal antibody to kininogens has been developed by the fusion of murine myeloma cells with mouse splenocytes immunized with bradykinin-conjugated hemocyanin. The hybrid cells were screened by an enzyme-linked immunosorbent assay (ELISA) and a radioimmunoassay (RIA) for the secretion of antibodies to bradykinin. Ascitic fluids were produced and purified by a bradykinin-agarose affinity column. The monoclonal antibody (IgG1) bound to bradykinin, Lys-bradykinin, Met-Lys-bradykinin, and kininogens in ELISA. Further, this target-directed monoclonal antibody recognized purified low and high molecular weight bovine, human, or rat kininogens and T-kininogen in Western blotting. After turpentine-induced acute inflammation, rat kininogen levels increased dramatically in liver and serum as well as in the perfused pituitary, heart, lung, kidney, thymus, and other tissues, as identified by the kinin-directed kininogen antibody in Western blot analyses. The results were confirmed by measuring kinin equivalents of kininogens with a kinin RIA. During an induced inflammatory response, rat kininogens were localized immunohistochemically with the kinin-directed monoclonal antibody in parenchymal cells of liver, in acinar cells and some granular convoluted tubules of submandibular gland, and in the collecting tubules of kidney. Northern and cytoplasmic dot blot analyses using a kinin oligonucleotide probe showed that kininogen mRNA levels in liver but not in other tissues increase after turpentine-induced inflammation. The results indicated that rat kininogens are distributed in various tissues in addition to liver and only liver kininogen is induced by acute inflammation. The target-directed kininogen monoclonal antibody is a useful reagent for studying the structure, localization, and function of kininogens or any protein molecule containing the kinin moiety. 相似文献
932.
933.
934.
935.
C Rudowicz 《Biochimica et biophysica acta》1977,490(2):301-310
The electronic structure of high-spin S = 2 ferrous ion in deoxy forms of hemoglobin and myoglobin is considered in terms of spin Hamiltonian formalism. Spin Hamiltonian parameters of the second order B0(2)(D), B2(2)(E) and, for the first time in the available literature, of fourth order B0(4), B2(4) and B4(4), are calculated for the rhombic symmetry case of Fe2+. The Hamiltonian matrix is diagonalized for several sets of Bq(k) parameters compatible with other experimental data. The low-lying Fe2+ levels exhibit crossings in a high magnetic field, applied along the z-axis perpendicular to the heme plane. The cross-over values of the magnetic field are determined to be Hc1 = 46 kOe and Hc2 = 168 kOe for D = 5.2, E = 0.6 cm-1 (close to the magnetic data of Nakano, N., Otsuka, J. and Tasaki, A. (1972) Biochim. Biophys. Acta 278, 355-371) and with B0(4) = 0.037, B2(4) = 0.005, B4(4) = 0.013 cm-1 and gz = 2.028. Experimental techniques for measurement of the crossing effects are discussed. 相似文献
936.
937.
938.
939.
Meal prepared from unheated rapeseed (Brassica napus cv. Zephyr) showed the presence of t,iocyanate ion, while meal from heated seed of the same cultivar did not show detectable amounts. Unheated seed meal on autolysis, and heated seed meal on incubation with thioglucosidase, yielded increased amounts of thiocyanate ion. Various commercial rapeseed meals showed the presence of t,iocyanate ion only after enzyme incubation. Low glucosinolate, cv. Bronowski, and higher glucosinolate, cv. Zephyr on enzymic incubation yielded comparable amounts of thiocyanate ion, suggesting that the precursor responsible in the two varieties was the same and present in similar quantities. No formation of thiocyanate ion was observed on incubation of sinigrin with thioglucosidase. Rats dosed with heated meal, containing intact glucosinolate, showed a slight increase of thiocyanate ion in the urine as compared with control rats dosed with water, while a relatively large increase followed dosing with sinigrin. Rats dosed with meal containing free thiocyanate ion excreted the ingested thiocyanate ion almost quantitatively. 相似文献
940.