全文获取类型
收费全文 | 42045篇 |
免费 | 3717篇 |
国内免费 | 206篇 |
出版年
2018年 | 509篇 |
2017年 | 495篇 |
2016年 | 644篇 |
2015年 | 714篇 |
2014年 | 918篇 |
2013年 | 1097篇 |
2012年 | 1237篇 |
2011年 | 1269篇 |
2010年 | 862篇 |
2009年 | 873篇 |
2008年 | 1180篇 |
2007年 | 1175篇 |
2006年 | 1177篇 |
2005年 | 1006篇 |
2004年 | 965篇 |
2003年 | 912篇 |
2002年 | 889篇 |
2001年 | 2776篇 |
2000年 | 2454篇 |
1999年 | 1800篇 |
1998年 | 614篇 |
1997年 | 525篇 |
1996年 | 470篇 |
1995年 | 400篇 |
1994年 | 386篇 |
1992年 | 1282篇 |
1991年 | 1159篇 |
1990年 | 1095篇 |
1989年 | 1043篇 |
1988年 | 928篇 |
1987年 | 922篇 |
1986年 | 802篇 |
1985年 | 793篇 |
1984年 | 563篇 |
1983年 | 513篇 |
1982年 | 366篇 |
1979年 | 630篇 |
1978年 | 451篇 |
1977年 | 414篇 |
1976年 | 368篇 |
1975年 | 494篇 |
1974年 | 575篇 |
1973年 | 553篇 |
1972年 | 571篇 |
1971年 | 548篇 |
1970年 | 520篇 |
1969年 | 526篇 |
1968年 | 426篇 |
1967年 | 373篇 |
1966年 | 409篇 |
排序方式: 共有10000条查询结果,搜索用时 265 毫秒
151.
152.
153.
V V Tertov I A Sobenin Z A Gabbasov E G Popov A N Orekhov 《Biulleten' eksperimental'no? biologii i meditsiny》1990,110(7):34-36
Spontaneous aggregation of glycosylated, desialated, oxidized and malondialdehyde modified low density lipoprotein (LDL) as well as LDL of coronary heart disease patients has been discovered using methods for determination of light transmission fluctuations in suspensions and gel filtration. At the same time; LDL of healthy donors failed to aggregate under conditions of cellular culture. On the other hand, human aortic cells from unaffected intima incubated with modified LDL, but not native LDL of healthy donors, showed a rise in esterified cholesterol levels. There was a strong correlation between the degree of LDL aggregation and intracellular cholesterol ester accumulation (r-0.86, p 0.001, n-21). Removal of aggregates by passing preparations through and 0.1 um filter significantly inhibited the accumulation of cholesterol esters. The obtained data point to the essential, if not decisive, role of LDL aggregation in the processes of lipid accumulation by intimal cells in vitro. 相似文献
154.
155.
Antiparallel microtubule interactions: spindle formation and anaphase B 总被引:10,自引:0,他引:10
156.
The development of tumorigenic conditions in the carcinogen-exposed rat colon was studied using selected morphological, histochemical, immunohistochemical and biochemical methods of analysis. Rats were treated with two carcinogens: 1,2-dimethylhydrazine and N-methyl-N'-nitro-N-nitrosoguanidine alone or with deoxycholic acid as a tumor promoter. It was found that 3 months after treatment of animals with the carcinogens the following changes were developed in colonic tissue: infiltration of lymphocytes in the mucous membrane, high increase in mitotic index among epithelial cells, negative reactions of colonic cells for neutral mucopolysaccharides and sulfomucins and positive reactions to carboxyl groups, nonsulfated acid mucosubstances and tissue polypeptide antigens. An increase in the activity of ornithine decarboxylase in colonic tissue was developed within the same time period and has been seen only in those tissues which were characterized by the development of precancerous conditions. Individual variations were observed in the manifestation of the studied parameters in rat neoplastic colonic tissues. It is suggested that these differences reflect an individual sensitivity of animals to carcinogens and the magnitude of the dysplastic processes induced in the colon. 相似文献
157.
158.
Measurements have been made of the activities of enzymes of the pentose phosphate pathway, the glucuronate-xylulose pathway, hexokinase and phosphofructokinase in kidney of diabetic and normal rats. The activities of these enzymes keep pace with kidney growth, remaining constant per gram tissue but showing a marked increase on the basis of total activity per 100 g body wt. The formation of 14CO2 from [1-14C]glucose and [6-14C]glucose by kidney slices from diabetic rats was decreased to approximately half the control value; evidence was obtained for an equivalent dilution of the glucose 6-phosphate pool. Correction of the 14CO2 yields for the change in specific activity of glucose 6-phosphate yielded values consistent with the enzyme profile. Calculations from specific yields of 14CO2 provided evidence for an increased flux of glucose via the pentose phosphate pathway in the kidney in diabetes. The results are discussed in relation to kidney hypertrophy in diabetes and the requirement for ribose 5-phosphate and NADPH for biosynthetic reactions and in relation to the thickening of the basement membrane in diabetes. These results are in accord with the concept of glucose overutilization by non-insulin-requiring tissues. 相似文献
159.
Z N Zhuravleva 《Ontogenez》1987,18(4):369-379
Embryonic tissues of septum and hippocampus were transplanted into the anterior eye chamber (AEC) of adult rats. The morphology of initial embryonic tissues and of transplants within 3 to 4 months of cultivation in AEC was studied. The transplanted tissue consists of neuroblasts and immature neurones: no synaptic contacts are observed. Within 3 to 4 months, highly differentiated neurones establishing synaptic contacts can be seen in the transplants. At the same time the fine structure of perikaryons and dendrites undergoes some changes: increased vacuolization, transformation of ergastoplasm into lamellar bodies. These can be due to an elevated functional activity of some neurones. Another group of morphological abnormalities (increased number of dendrite processes and microphyllopodia, somatic spines, dendrite cones of growth, tight junctions between perikaryons) suggests incomplete tissue maturation. These might be due to the absence of normal afferent and trophic influences in AEC. 相似文献
160.