全文获取类型
收费全文 | 6853篇 |
免费 | 342篇 |
国内免费 | 109篇 |
出版年
2024年 | 19篇 |
2023年 | 244篇 |
2022年 | 237篇 |
2021年 | 304篇 |
2020年 | 294篇 |
2019年 | 472篇 |
2018年 | 307篇 |
2017年 | 269篇 |
2016年 | 210篇 |
2015年 | 296篇 |
2014年 | 608篇 |
2013年 | 671篇 |
2012年 | 529篇 |
2011年 | 507篇 |
2010年 | 392篇 |
2009年 | 263篇 |
2008年 | 206篇 |
2007年 | 244篇 |
2006年 | 177篇 |
2005年 | 161篇 |
2004年 | 150篇 |
2003年 | 103篇 |
2002年 | 77篇 |
2001年 | 36篇 |
2000年 | 41篇 |
1999年 | 31篇 |
1998年 | 45篇 |
1997年 | 41篇 |
1996年 | 23篇 |
1995年 | 22篇 |
1994年 | 26篇 |
1993年 | 26篇 |
1992年 | 12篇 |
1991年 | 18篇 |
1990年 | 9篇 |
1989年 | 8篇 |
1988年 | 10篇 |
1987年 | 10篇 |
1986年 | 8篇 |
1985年 | 9篇 |
1984年 | 30篇 |
1983年 | 23篇 |
1982年 | 22篇 |
1981年 | 19篇 |
1980年 | 16篇 |
1979年 | 15篇 |
1978年 | 8篇 |
1977年 | 12篇 |
1976年 | 15篇 |
1975年 | 18篇 |
排序方式: 共有7304条查询结果,搜索用时 15 毫秒
31.
Expression of galectins on microvessel endothelial cells and their involvement in tumour cell adhesion 总被引:5,自引:0,他引:5
Reuben Lotan Paula N. Belloni Robert J. Tressler Dafna Lotan Xiao-Chun Xu Garth L. Nicolson 《Glycoconjugate journal》1994,11(5):462-468
Lactoside-binding lectins (galectins) with molecular weights of about 14.5 kDa (galectin-1) and 29–35 kDa (galectin-3) bind preferentially to polylactosaminoglycan-containing glycoconjugates and have been found on the surface of tumour cells and implicated in cell-cell and cell-extracellular matrix adhesion and metastasis. We have demonstrated by immunoblotting that both galectin-1 and galectin-3 are present in extracts of endothelial cells cultured from bovine aorta, rat lung, mouse lung and mouse brain microvessels, whereas mouse hepatic sinusoidal endothelial cells expressed primarily galectin-1. These galectins were also localized by indirect immunofluorescent labelling on the surface of the different endothelial cells in culture and by immunohistochemical staining in human tissuesin vivo. Anti-galectin-1 antibodies inhibited the adhesion of liver-preferring murine RAW117-H10 large-cell lymphoma cells to hepatic sinusoidal endothelial cells or lung microvessel endothelial cellsin vitro. The data indicate that galectin-1 is expressed on the extracellular surface of endothelial cells and can mediate in part the adhesion of RAW117-H10 cells to liver microvessel endothelial cells. 相似文献
32.
B. Vanderschueren J. C. Dumon V. Oleffe C. Heymans J. Gérain J. J. Body 《Cancer immunology, immunotherapy : CII》1994,39(5):286-290
Circulating interleukin-6 (IL-6) concentrations correlate with disease activity in severe inflammatory conditions, in sepsis and in some hematological malignancies. On the other hand, IL-6 is a potent stimulator of osteoclastogenesis and has been implicated as a contributory factor in the genesis of osteopenic conditions. We measured circulating IL-6 levels by a sensitive (detection limit of 10 U/ml) and specific bioassay in 103 patients with advanced cancer, including 41 with tumor-induced hypercalcemia before any specific hypocalcemic therapy. We related IL-6 concentrations to clinical features and to biochemical parameters of bone metabolism, including blood Ca, Ca2+, Pi, intact parathyroid hormone, parathyroid hormone-related protein, osteocalcin, 1,25-(OH)2-vitamin D and, as markers of bone resorption, the fasting urinary excretion of calcium (Ca/creatinine) and hydroxyproline. IL-6 levels were increased, i.e. detectable, in 23% of the patients, 8/41 (20%) hypercalcemic and 16/62 (26%) normocalcemic patients (NS); the distribution of the values was similar in the two groups. The presence of increased IL-6 concentrations was not related to any clinical characteristic, notably not to the survival nor to the existence of bone metastases, whether in hypercalcemic or normocalcemic patients; e.g., only 3/12 (25%) hypercalcemic subjects without bone metastases had elevated IL-6 levels. We found no significant correlations between IL-6 concentrations and any of the biochemical parameters studied. Hypercalcemic subjects with increased IL-6 had higher urinary Ca/creatinine levels than patients with normal IL-6 levels (P<0.005) but this was not the case in normocalcemic subjects. Mean concentrations of inflammatory or other bone metabolism markers were not significantly different between patients with normal or with elevated IL-6 levels. In summary, circulating IL-6 levels were increased in 23% of 103 patients with advanced cancer, but the frequency of increased IL-6 concentrations was not related to the presence of hypercalcemia or to any marker of calcium metabolism or bone turnover. The pathogenic importance of circulating IL-6 in patients with solid tumors remains to be demonstrated and our data indicate that increased circulating levels of IL-6, possibly reflecting the activation of the immune system, only contribute in a minor way to the osteolytic process in patients with tumor-induced hypercalcemia. 相似文献
33.
Arjan W. Griffioen Eveliene Horst Karl Heinz Heider Vera J. M. Wielenga GÜ Unther R. Adolf Peter Herrlich Steven T. Pals 《Cell communication & adhesion》1994,2(3):195-200
Recently, splice variants of CD44 have been described that confer metastatic potential to non-metastasizing rat pancreatic carcinoma and sarcoma cell lines. Using antibodies against variant CD44 (CD44v) sequences, we have examined the expression of variant CD44 glycoproteins on human lymphoid cells and tissues and in colorectal neoplasia. Lymphohematopoietic cells express low levels of CD44v glycoproteins. During the process of lymphocyte activation in vitro and in vivo, expression of CD44v glycoproteins is transiently upregulated. The reaction pattern of various antibodies indicates that these CD44 variants contain the domain encoded by exon v6, which is part of the variant that confers metastatic capability. In human colorectal neoplasia we observed overexpression of CD44 splice variants in all invasive carcinomas. Already at early stages of colorectal tumor progression exon v5 epitopes were overexpressed. Tumor progression was strongly related to expression of CD44 isoforms containing exon v6 encoded domains. The findings establish CD44 variants as tumor progression markers in colorectal cancer. 相似文献
34.
本实验合并应用枸杞有效成份和大蒜有效成份,作用于U_14腹水型宫颈癌小鼠,腹腔注射第四天,发现一般状况改善,取腹水观察,癌细胞破损,DNA、RNA荧光染色强度减弱,有大量白细胞和巨噬细胞围绕;流式细胞分析G_1期细胞堆积,超微结构显示胞质中线粒体肿胀,嵴破坏甚至中空,粗面内质网扩大、脱颗粒,肯定了其作用的效果。此因枸杞有效成分活化巨噬细胞与肿瘤细胞紧密结合而起到溶瘤作用,与大蒜有效成分直接杀伤而作用维持短暂结合起来,可大大提高抗癌作用。 相似文献
35.
The rise of supramolecular chemistry offers new tools to design therapeutics and delivery platforms for biomedical applications. This review aims to highlight the recent developments that harness host-guest interactions and self-assembly to design novel supramolecular Pt complexes as anticancer agents and drug delivery systems. These complexes range from small host-guest structures to large metallosupramolecules and nanoparticles. These supramolecular complexes integrate the biological properties of Pt compounds and novel supramolecular structures, which inspires new designs of anticancer approaches that overcome problems in conventional Pt drugs. Based on the differences in Pt cores and supramolecular structures, this review focuses on five different types of supramolecular Pt complexes, and they include host-guest complexes of the FDA-approved Pt(II) drugs, supramolecular complexes of nonclassical Pt(II) metallodrugs, supramolecular complexes of fatty acid-like Pt(IV) prodrugs, self-assembled nanotherapeutics of Pt(IV) prodrugs, and self-assembled Pt-based metallosupramolecules. 相似文献
36.
37.
BackgroundThe impact of the coronavirus disease 2019 (COVID-19) pandemic on cancer screening participation is a global concern. A national database of screening performance is available in Japan for population-based cancer screening, estimated to cover approximately half of all cancer screenings.MethodsUtilizing the fiscal year (FY) 2017–2020 national database, the number of participants in screenings for gastric cancer (upper gastrointestinal [UGI] series or endoscopy), colorectal cancer (fecal occult blood test), lung cancer (chest X-ray), breast cancer (mammography), and cervical cancer (Pap smear) were identified. The percent change in the number of participants was calculated.ResultsCompared with the pre-pandemic period (FY 2017–2019), in percentage terms FY 2020 recorded the largest decline in gastric cancer UGI series (2.82 million to 1.91 million, percent change was −32.2 %), followed by screening for breast cancer (3.10 million to 2.57 million, percent change was −17.2 %), lung cancer (7.92 million to 6.59 million, percent change was −16.7 %), colorectal cancer (8.42 million to 7.30 million, percent change was −13.4 %), cervical cancer (4.26 million to 3.77 million, percent change was −11.6 %), and gastric cancer via endoscopy (1.02 million to 0.93 million, percent change was −9.0 %).ConclusionThe number of participants in population-based screenings in Japan decreased by approximately 10–30 % during the pandemic. The impact of these declines on cancer detection or mortality should be carefully monitored. 相似文献
38.
Payne DA Chan Ts Ostermeyer Schoaib B Patten BM Tyring SK 《Journal of biomedical science》1996,3(5):319-322
When monoclonal gammopathies arise in persons without evidence of plasma cell malignancy or lymphoproliferative disease, the term monoclonal gammopathy of unknown significance (MGUS) can be used. MGUS is believed to be the preneoplastic phase of lymphoproliferative diseases because many of these patients eventually develop malignant disease, mainly multiple myeloma. We have previously identified human papillomavirus (HPV) in a chronic benign plasma cell tumor of the cervix and in the bone marrow of multiple-myeloma patients. In the following study, we expanded upon our initial observation by analyzing 14 patients with MGUS. Bone marrow biopsies of the patients were analyzed for HPV sequences using polymerase chain reaction (PCR) and in situ hybridization. Normal controls included 26 bone marrow specimens, 24 analyzed by PCR and two by in situ hybridization. A significant association was found to exist between HPV and MGUS (p=0.001). Among 14 patients iwth MGUS, HPV sequences have been identified in 10 of the bone marrow biopsies. These results suggest that HPV can reside in the bone marrow of a premalignant lymphoproliferative disease. 相似文献
39.
Y-organs are the ecdysial glands of crustaceans, responsible for synthesis and secretion of ecdysteroid hormones. For this purpose, the glands acquire cholesterol as obligate precursor entirely from circulating high-density lipoprotein (HDL). A preceding study provided evidence for the mechanism of acquisition: Y-organs take up cholesterol bound to HDL by an energy-requiring process, receptor-mediated absorptive endocytosis. The present study characterized the receptors involved utilizing isolated Y-organ membranes. HDL binding was saturable and specific; a dissociation constant (Kd) of 1.08 × 10?7 M and a binding maximum at equilibrium (Bmax) of 70 μg HDL protein/mg membrane protein, were obtained. Binding was decreased by protease and was dependent upon calcium. Y-organs are regulated negatively by a peptide hormone from the eystalks, molt-inhibiting hormone (MIH). Y-organ membranes from de-eyestalked crabs (MIH absent) exhibited the same Kd value as membranes from intact crabs, but a Bmax 17% higher. Thus, MIH activity apparently does not change the binding affinity of HDL, but decreases the number of binding sites. These results agree with our previous findings that MIH depresses ecdysteroid synthesis in part by inhibiting cholesterol uptake. Generally, Y-organ cells appear to contain receptors for HDL that are of high affinity and high binding capacity, similar to the characteristics reported for the binding of insect HDL (vitellogenin) to fat bodies and oocytes. © 1995 Wiley-Liss, Inc. 相似文献
40.
Therapy of bovine ocular squamous-cell carcinoma with local doses of interleukin-2: 67% complete regressions after 20 months of follow-up 总被引:1,自引:1,他引:0
F. W. Willem Den Otter Graham Hill Wim R. Klein Jan Willem Koten Peter A. Steerenberg Pieter H. M. De Mulder Christopher Rhode Rachel Stewart Joop A. J. Faber E. Joost Ruitenberg Victor P. M. G. Rutten 《Cancer immunology, immunotherapy : CII》1995,41(1):10-14
We have tested the therapeutic potency of peritumorally injected low doses of interleukin-2(IL-2). Seventy tumours of the bovine ocular squamous-cell carcinoma (BOSCC), 1–3 cm in diameter, were treated with 5000, 20 000 or 200 000 U IL-2 from Eurocetus (Chiron) to find the optimal dose for treatment. Injections were given peritumorally on Monday to Friday on 2 consecutive weeks. The size of the tumours was measured before treatment and 1, 3, 4, 9 and 20 months after treatment. After 9 months complete regression was observed in 89% of the tumours treated with 5000 U IL-2, 80% treated with 20 000 U and 67% treated with 200 000 U. After 20 months, there was complete regression of 35%, 31% and 67% of the tumours respectively. The 9-and 20-month results of the 200 000-U treatment are significantly better than those of the 5000-U and 20 000-U treatments taken together. This protocol may be useful to treat advanced inoperable tumours (e.g. of the nasopharynx or skin) of human patients. 相似文献