全文获取类型
收费全文 | 181272篇 |
免费 | 14338篇 |
国内免费 | 49篇 |
出版年
2018年 | 1807篇 |
2017年 | 1756篇 |
2016年 | 2248篇 |
2015年 | 2137篇 |
2014年 | 2935篇 |
2013年 | 4188篇 |
2012年 | 4797篇 |
2011年 | 5304篇 |
2010年 | 3713篇 |
2009年 | 3350篇 |
2008年 | 4851篇 |
2007年 | 5124篇 |
2006年 | 4818篇 |
2005年 | 4537篇 |
2004年 | 4687篇 |
2003年 | 4590篇 |
2002年 | 4572篇 |
2001年 | 8383篇 |
2000年 | 8579篇 |
1999年 | 6310篇 |
1998年 | 1989篇 |
1997年 | 2036篇 |
1996年 | 1802篇 |
1995年 | 1674篇 |
1992年 | 5197篇 |
1991年 | 5362篇 |
1990年 | 5139篇 |
1989年 | 5116篇 |
1988年 | 4732篇 |
1987年 | 4485篇 |
1986年 | 4077篇 |
1985年 | 4234篇 |
1984年 | 3408篇 |
1983年 | 2911篇 |
1982年 | 1929篇 |
1981年 | 1728篇 |
1980年 | 1718篇 |
1979年 | 3211篇 |
1978年 | 2545篇 |
1977年 | 2278篇 |
1976年 | 2081篇 |
1975年 | 2546篇 |
1974年 | 2884篇 |
1973年 | 2802篇 |
1972年 | 2651篇 |
1971年 | 2415篇 |
1970年 | 2116篇 |
1969年 | 2022篇 |
1968年 | 1906篇 |
1967年 | 1743篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
981.
I Urasiński G Uhlenbruck C Dienst 《Folia haematologica (Leipzig, Germany : 1928)》1985,112(3):403-408
The capacity to phagocytosis in monocytic macrophages was investigated in 24 patients with plasmocytoma. The investigation of this capacity was made by using short-term cultures with sheep erythrocytes loaded with antibodies and complement. In comparison to the control group the percentage of phagocyting macrophages was lowered in 16 from 24 patients. This impairment of the function of monocytic macrophages seems to be bound neither to the type of plasmocytoma nor to the stage of disease. Among other things, the nature of cell defect is discussed. The necessity of further investigations is emphasized. 相似文献
982.
Nikolas K. Haass D. Ripperger E. Wladykowski P. Dawson P. A. Gimotty C. Blome F. Fischer P. Schmage I. Moll Johanna M. Brandner 《Histochemistry and cell biology》2010,133(1):113-124
Melanoma depends on, interacts with and reacts to the stroma in which it is embedded, including fibroblasts, extracellular
matrix, endothelial cells and immune cells. However, the impact of melanoma on the epidermal tumor microenvironment—the multilayered
epithelium of the skin—is poorly understood. Gap junctions are essential for intercellular communication and involved in proliferation,
differentiation and homeostasis of keratinocytes. We have shown previously that the gap junction proteins connexin 26 and
30 (Cx26 and Cx30) are induced in the epidermal tumor microenvironment of skin cancers including melanoma. This study compares
the extent of Cx26, Cx30 and Cx43 expression in the epidermal microenvironment of melanocytic nevi and melanomas and its association
with melanoma thickness, proliferative index of the tumor and its microenvironment, and with 5-year metastasis and survival.
We found that induction of Cx26 and Cx30 cell–cell border expression in the epidermal tumor microenvironment correlates to
malignancy. Importantly, there was a significant correlation of tumor thickness with the vertical epidermal Cx26 and Cx30
expression pattern and the horizontal Cx26 dissemination. Furthermore, horizontal Cx26 expression correlated with metastasis.
Vertical epidermal expression patterns of Cx26 and Cx30 significantly correlated with the proliferative index in the epidermal
tumor microenvironment but not with the proliferative index in the tumor. In contrast, Cx43 did not correlate with malignancy,
thickness or proliferative index. In summary, here we show for the first time a significant association between the progression
of melanoma and alterations in its epithelial tumor microenvironment. 相似文献
983.
David Philip Arthur Craig James W. Grice Chris A. Varnon B. Gibson Michel B. C. Sokolowski Charles I. Abramson 《PloS one》2012,7(10)
Free-flying honey bees (Apis mellifera L.) reactions were observed when presented with varying schedules of post-reinforcement delays of 0 s, 300 s, or 600 s. We measured inter-visit-interval, response length, inter-response-time, and response rate. Honey bees exposed to these post-reinforcement delay intervals exhibit one of several patterns compared to groups not encountering delays, and had longer inter-visit-intervals. We observed no group differences in inter-response time. Honey bees with higher response rates tended to not finish the experiment. The removal of the delay intervals increased response rates for those subjects that completed the trials. 相似文献
984.
985.
986.
987.
9S globin mRNA prepared by the proteinase K method from polysomes of rabbit reticulocytes consists of 40% circular molecules as revealed by electron microscopy, if spreading of the molecules is performed from a solution of 50% formamide, 0.5 M NaCl, 25 mM Tris, 10 mM EDTA, pH 8, after 16 h incubation at 42 °C. We assume a noncovalent nature of the circularization because of the fact that a total transformation into the well known linear form occurs if strong denaturing conditions for spreading were used. The biological significance of the circular globin mRNA molecules is unknown. 相似文献
988.
I L Trapani 《Federation proceedings》1969,28(3):1104-1106
989.
The role of leukocyte transfusions in the prevention and treatment of infections in adults with granulocytopenia was investigated. Leukocytes were obtained from healthy volunteers by continuous-flow centrifugation. Histocompatibility antigen (HLA)-matched leukocytes were used to assess the prophylactic value of leukocyte transfusions. Seven patients with acute myelogenous leukemia received HLA-matched leukocytes during the period of maximal granulocytopenia associated with initial remission induction therapy; 20 concurrently treated patients who did not receive leukocyte transfusions were the control group. The patients receiving HLA-matched leukocytes had significantly fewer (P = 0.043) infectious episodes (not bacteriologically proven) during the study period, and remission occurred in 5 of the 7, compared with 10 of the 20 controls. In addition, 52 series of two or more ABO-compatible transfusions were given to 50 patients with proven infection or elevated temperature presumed due to infection and a granulocyte count of less than 0.5 X 10(9)/L. Response, indicated by a decrease in temperature, occurred in 23 patients. Leukocyte transfusions thus have an important adjuvant role in the management of patients with severe granulocytopenia. 相似文献
990.