全文获取类型
收费全文 | 18865篇 |
免费 | 1719篇 |
国内免费 | 1484篇 |
出版年
2024年 | 46篇 |
2023年 | 207篇 |
2022年 | 426篇 |
2021年 | 821篇 |
2020年 | 531篇 |
2019年 | 671篇 |
2018年 | 739篇 |
2017年 | 560篇 |
2016年 | 761篇 |
2015年 | 1266篇 |
2014年 | 1362篇 |
2013年 | 1485篇 |
2012年 | 1754篇 |
2011年 | 1718篇 |
2010年 | 1066篇 |
2009年 | 903篇 |
2008年 | 1179篇 |
2007年 | 1097篇 |
2006年 | 887篇 |
2005年 | 820篇 |
2004年 | 746篇 |
2003年 | 598篇 |
2002年 | 517篇 |
2001年 | 182篇 |
2000年 | 187篇 |
1999年 | 170篇 |
1998年 | 139篇 |
1997年 | 137篇 |
1996年 | 109篇 |
1995年 | 107篇 |
1994年 | 75篇 |
1993年 | 54篇 |
1992年 | 47篇 |
1991年 | 47篇 |
1990年 | 49篇 |
1989年 | 34篇 |
1988年 | 37篇 |
1987年 | 39篇 |
1986年 | 33篇 |
1985年 | 31篇 |
1984年 | 47篇 |
1983年 | 23篇 |
1982年 | 28篇 |
1981年 | 26篇 |
1978年 | 16篇 |
1977年 | 21篇 |
1976年 | 20篇 |
1975年 | 22篇 |
1974年 | 17篇 |
1973年 | 19篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
131.
132.
Metastasis formation is a major clinical problem in cancer treatment, and no significant progress in the treatment of metastatic
spread has been made. This apparent lack of progress is partly caused by the absence of clinically relevant animal models
of meta stases. The binding of the lectin Helix pomatia agglutinin (HPA) has been associated with a poor prognosis in breast
and colon cancer patients. HPA-positive and -negative human breast and colon cancer cell lines were transplanted into severe
combined immunodeficient (SCID) mice. HPA-positive breast cancer cell lines (MCF-7 and T47D) metastasized in SCID mice, whereas
the HPA-negative ones (BT20, HS578T and HBL100) did not. The HPA-positive colon cancer cell line HT29 metastasized, while
the HPA-negative ones (COLO320DM, SW480 and SW620) did not. However, in two of eight SCID mice inoculated with the HPA-negative
colon cancer cell line, CACO2 metastatic deposits were found. Despite this exception, HPA binding is a good indicator of the
metastasis of human breast and colon cancer cells in SCID mice: 23 out of 26 HPA-positive cancers metastasized, as opposed
to only two out of 38 HPA-negative cancers. This experimental model is well suited for investigating the functional role of
carbohydrate residues recognized by HPA in breast and colon cancer metastasis.
This revised version was published online in November 2006 with corrections to the Cover Date. 相似文献
133.
Xue Bin Zheng Misao Tsubokura Yongkun Wang Chun Xie Tetsuji Nagano Kazuhiko Someya Tomoko Kiyohara Kiyomi Suzuki Takeshi Sanekata 《Microbiology and immunology》1995,39(10):821-824
Thirty strains of Yersinia pseudotuberculosis were isolated from rabbits (17 strains), wild rats (9 strains) and house rats (4 strains) in China between 1990 and 1993. The biochemical properties of these isolates were identical with those of Y. pseudotuberculosis and no special characteristics were found in these strains. Serologically, serogroups 4b and 5b were identical to isolates found in Japan, and a new serogroup 1c and unclassified strains have also been detected. The existence of virulence-associated properties were different among strains. The pYV plasmid was detected from 6 strains of 30 isolates. This report documents the presence of Y. pseudotuberculosis in China, providing important epidemiological information. 相似文献
134.
Witold Lasek Anna Wańkowicz Katarzyna Kuc Wojciech Feleszko Jakub Golab Adam Giermasz Wiesŀaw Wiktor-J/cedrzejczak Marek Jakóbisiak 《Cancer immunology, immunotherapy : CII》1995,40(5):315-321
The efficacy of systemic infusion of recombinant human macrophage-colony-stimulating factor (M-CSF) in combination with local treatment with human recombinant tumor necrosis factor (TNF) and mouse recombinant interferon (IFN) was studied in vivo on a subclone of B16 melanoma (MmB16) in mice. Short-term intravenous administration of M-CSF at a dose of 106 units daily had no antitumor effect in vivo. Similarly, local treatment of tumor with TNF (5 g daily) did not produce any therapeutic effect. However, simultaneous administration of the same dose of TNF with IFN (1000 units daily) resulted in a synergistic effects manifested by the retardation of tumor growth. Addition of systemic infusion of M-CSF to the local therapy with TNF and IFN induced further augmentation of antitumor efficacy and delayed progression of MmB16 melanoma. The strengthened antitumor effect of combination therapy including M-CSF, TNF and IFN was most probably due to the increased release of monocytes from the bone marrow, their recruitment into the site of tumor growth and subsequent local stimulation of their antitumor activity. 相似文献
135.
136.
Gracjana Klein Robert Walczak Ewa Krasnowska Adam Blaszczak Barbara Lipiska 《Molecular microbiology》1995,16(4):801-811
We have investigated heat-shock response in a marine bacterium Vibrio harveyi. We have found that 39 C was the highest tempature at which V. harveyi was able to grow steadily. A shift from 30° C to 39° C caused increased synthesis of at least 10 proteins, as judged by SDS-PAGE, with molecular masses of 90, 70, 58, 41, 31, 27, 22, 15, 14.5 and 14kDa. The 70, 58, 41 and 14.5 kDa proteins were immunologically homologous to DnaK, GroEL, DnaJ and GroES heat-shock proteins of Escherichia coli, respectively. V. harveyi GroES protein had a lower molecular mass (14.5 kDa) than E. coli GroES, migrating in SDS-PAGE as 15 kDa protein. We showed that a protein of ~43 kDa, immunologically reactive with antiserum against E. coli sigma 32 subunit (σ32) of RNA polymerase, was induced by heat-shock and co-purified with V. harveyi RNA polymerase. These results suggest that the 43 kDa protein is a heat-shock sigma protein of V. harveyi. Preparation containing the V. harveyi sigma 32 homologue, supplemented with core RNA polymerase of E. coli, was able to transcribe heat-shock promoters of E. coli in vitro. 相似文献
137.
四川地区幼儿和学龄前儿童的鼻部测量 总被引:2,自引:0,他引:2
本文报告1116例四川地区幼儿和学龄前儿童(2-7岁)鼻部9项指标的测量均数,性差及年龄发育特点。性差:仅鼻凹鼻底距4-6.5岁等少数指标部分年龄段男女性间出现显著性划异(男>女)。此外各项指标的绝大多数年龄段男女性间无显著性差异。年龄发育:9项测量指标中7项的生长曲线随年产长而上升,数值随年龄增大,并有1-2个发育高峰;提示鼻部发育具有阶段性;2项指标的曲线随年龄增长变化较小。4项指标男女性的曲 相似文献
138.
合成了2-氯-5-正十二硫烷基-6-甲基-4,7-苯并噻唑醌(2-Cl-DMMDBT)和2-氯-5-正丁烷氨基-6-甲基-4,7-苯并噻唑醌(2-Cl-BAMDBT)两种化合物,研究了它们对线粒体呼吸链酶系的抑制作用.结果表明:2-Cl-DMMDBT和2-C1-BAMDBT对琥珀酸氧化酶及泛醌氧化酶的电子传递活性均表现一定的抑制作用,而对细胞色素氧化酶无作用,说明二者的抑制作用发生在泛醌反应区.二者对NADH氧化酶的抑制行为略有不同,2-Cl-DMMDBT是一个逐渐加强的过程,最终可致酶活性完全抑制,而2-Cl-BAMDBT则表现为瞬间抑制.比较了2-Cl-DMMDBT和2-Cl-BAMDBT对琥珀酸氧化酶的抑制能力,长侧链的2-Cl-DMMDBT比短侧链的2-Cl-BAMDBT抑制能力强很多. 相似文献
139.
140.