全文获取类型
收费全文 | 1695186篇 |
免费 | 123721篇 |
国内免费 | 3781篇 |
专业分类
耳鼻咽喉 | 21730篇 |
儿科学 | 55634篇 |
妇产科学 | 46151篇 |
基础医学 | 241205篇 |
口腔科学 | 48741篇 |
临床医学 | 151308篇 |
内科学 | 333485篇 |
皮肤病学 | 38651篇 |
神经病学 | 131136篇 |
特种医学 | 63880篇 |
外国民族医学 | 242篇 |
外科学 | 257227篇 |
综合类 | 38946篇 |
现状与发展 | 4篇 |
一般理论 | 531篇 |
预防医学 | 124222篇 |
眼科学 | 40211篇 |
药学 | 123602篇 |
7篇 | |
中国医学 | 4476篇 |
肿瘤学 | 101299篇 |
出版年
2021年 | 12785篇 |
2019年 | 13521篇 |
2018年 | 19950篇 |
2017年 | 15214篇 |
2016年 | 16613篇 |
2015年 | 18958篇 |
2014年 | 26215篇 |
2013年 | 37944篇 |
2012年 | 52737篇 |
2011年 | 55419篇 |
2010年 | 32769篇 |
2009年 | 30691篇 |
2008年 | 51514篇 |
2007年 | 54794篇 |
2006年 | 55252篇 |
2005年 | 52535篇 |
2004年 | 50737篇 |
2003年 | 48147篇 |
2002年 | 46366篇 |
2001年 | 91782篇 |
2000年 | 93605篇 |
1999年 | 76959篇 |
1998年 | 19717篇 |
1997年 | 17267篇 |
1996年 | 17391篇 |
1995年 | 16742篇 |
1994年 | 15289篇 |
1993年 | 14071篇 |
1992年 | 57381篇 |
1991年 | 55270篇 |
1990年 | 52970篇 |
1989年 | 50747篇 |
1988年 | 46131篇 |
1987年 | 44937篇 |
1986年 | 42226篇 |
1985年 | 39987篇 |
1984年 | 29348篇 |
1983年 | 24908篇 |
1982年 | 13898篇 |
1979年 | 25529篇 |
1978年 | 17574篇 |
1977年 | 14906篇 |
1976年 | 13874篇 |
1975年 | 14563篇 |
1974年 | 17630篇 |
1973年 | 16944篇 |
1972年 | 15673篇 |
1971年 | 14453篇 |
1970年 | 13431篇 |
1969年 | 12517篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
931.
932.
933.
Céline Chipoy Martine Berreur Séverine Couillaud Gilbert Pradal Fran?ois Vallette Caroline Colombeix Fran?oise Rédini Dominique Heymann Frédéric Blanchard 《Journal of bone and mineral research》2004,19(11):1850-1861
The effects of OSM on proliferation and differentiation of osteosarcoma and nontransformed osteoblasts were analyzed. OSM downregulates osteoblast markers but induces the glial fibrillary acidic protein by the combined activation of PKCdelta and STAT3, offering new lines of therapeutic investigations. INTRODUCTION: Oncostatin M (OSM) is a multifunctional cytokine of the interleukin-6 family implicated in embryonic development, differentiation, inflammation, and regeneration of various tissues, mainly the liver, bone, and the central nervous and hematopoietic systems. One particularity of OSM relies on its growth inhibitory and pro-differentiating effects on a variety of tumor cell lines such as melanoma, providing arguments for a therapeutic application of OSM. The objective of this study was to analyze the effects of OSM on osteosarcoma cell lines proliferation and differentiation. MATERIALS AND METHODS: Proliferation was analyzed by 3H thymidine incorporation. Differentiation was analyzed by semiquantitative RT-PCR and immunocytochemistry for various markers. Alizarin red S staining was used to evaluate bone nodule formation. Morphological changes were studied by confocal and electron microscopy. Western blotting, kinases inhibitors, and dominant negative STAT3 were used to identified the signaling pathways implicated. RESULTS: OSM inhibits the growth of rat osteosarcoma cell lines as well as normal osteoblasts, in correlation with induction of the cyclin-dependent kinases inhibitor p21WAF1. However, OSM reduces osteoblast markers such as alkaline phosphatase, osteocalcin, and bone sialoprotein, leading to strong inhibition of mineralized nodule formation. This inhibitory effect is restricted to mature osteoblasts and differentiated osteosarcoma because OSM effectively stimulates osteoblast markers and bone nodule formation in early, but not late, bone marrow mesenchymal stem cell (BMSC) cultures. In osteosarcoma cells or BMSC, OSM induces expression of the glial fibrillary acidic protein (GFAP) as well as morphological and ultrastructural changes, for example, elongated shape and bundles of microfilaments in cell processes. Rottlerin (PKCdelta inhibitor), and to a lesser degree UO126 (MEK/ERK inhibitor), prevents the loss of osteoblastic markers by OSM, whereas dominant negative STAT3 prevents GFAP induction. CONCLUSIONS: These results highlight the particular gene expression profile of OSM-treated osteosarcoma cells and BMSCs, suggesting either a osteocytic or a glial-like phenotype. Together with the implication of PKCdelta, ERK1/2, and STAT3, these results offer new lines of investigations for neural cell transplantation and osteosarcoma therapy. 相似文献
934.
935.
M Kurimoto N Hayashi H Kamiyama S Nagai T Shibata T Asahi N Matsumura Y Hirashima S Endo 《Minimally invasive neurosurgery》2004,47(5):278-283
Neuronavigation has become an effective therapeutic modality and is used routinely for intra-axial tumor removal. This retrospective study was conducted to evaluate the clinical impact of neuronavigation and image-guided extensive resection for adult patients with supratentorial malignant astrocytomas. Between 1990 and 2002, 76 adult patients with pathologically confirmed malignant astrocytomas underwent craniotomy and removal of the tumors at the Toyama Medical and Pharmaceutical University Hospital. Of these 76 patients, 42 were treated using neuronavigation with conventional microneurosurgery and the other 34 were treated with conventional microneurosurgery alone. Postoperative early MRI with contrast enhancement was done, and gross total resection was defined as the complete absence of residual tumor. Survival time was analyzed with the Kaplan-Meier method. Prognostic factors were obtained from the Cox proportional hazards model. In univariate analysis, age (< 65), grade 3, preoperative KPS (>/= 80), use of neuronavigation, and gross total resection were significantly associated with longer survival. However, when the data were submitted to multivariate analysis, grade 3, preoperative KPS (>/= 80), and gross total resection were independent prognostic factors. The median survival periods of patients receiving gross total resection (vs. partial resection) and neuronavigation (vs. no neuronavigation) were 16 (vs. 9) months and 16 (vs. 10) months, respectively. The percentage of a gross total resection was significantly higher in the neuronavigation group compared to that in the no-navigation group (64.3 % vs. 38.2 %, p < 0.05). Neurological deterioration occurred in 4 of 42 (9.5 %) and in 6 of 34 (17.6 %) patients after surgery with neuronavigation and surgery without neuronavigation, respectively, although this difference was not statistically significant. Our results showed that neuronavigation increases the radicality in the resection of malignant astrocytomas and is objectively useful for improving survival time. 相似文献
936.
937.
938.
L Muscato R S Kidd 《The European journal of contraception & reproductive health care》2003,8(2):80-86
OBJECTIVES: To assess the attitudes and practices of contraceptive behaviors of Western Ukraine women. METHODS: A survey of 500 women in the Oblast was conducted to assess their knowledge, attitudes and practices on a variety of health topics. Convenience sampling was used to access the subjects in 16 different towns/villages in nine rayons throughout the Oblast. Respondents were asked more than 100 questions pertaining to their knowledge, attitudes and practices on a variety of health topics, including stress, contraception, breast health, sexually transmitted diseases, parity, abortion, nutrition, alcohol and tobacco use, domestic violence, and depression and mental health. RESULTS: Of married women, 44% (112/256) would terminate their pregnancy while 56% (144/256) said they would keep their baby. Of unmarried women, 35% (31/88) would abort while 65% (57/88) would keep their baby. A large proportion of married women (82%; 222/271) and unmarried women (70%; 52/74) did not use condoms at all. CONCLUSION: These results suggest lack of birth control education and contribution to poor protection from sexually transmitted infections. Higher abortion practices may also play a role in the infertility issues that Ukrainian women currently face. 相似文献
939.
940.