全文获取类型
收费全文 | 1903篇 |
免费 | 119篇 |
国内免费 | 25篇 |
专业分类
耳鼻咽喉 | 1篇 |
儿科学 | 153篇 |
妇产科学 | 22篇 |
基础医学 | 172篇 |
口腔科学 | 86篇 |
临床医学 | 173篇 |
内科学 | 408篇 |
皮肤病学 | 42篇 |
神经病学 | 65篇 |
特种医学 | 338篇 |
外科学 | 132篇 |
综合类 | 36篇 |
预防医学 | 88篇 |
眼科学 | 46篇 |
药学 | 161篇 |
1篇 | |
中国医学 | 3篇 |
肿瘤学 | 120篇 |
出版年
2023年 | 6篇 |
2022年 | 16篇 |
2021年 | 32篇 |
2020年 | 26篇 |
2019年 | 21篇 |
2018年 | 35篇 |
2017年 | 28篇 |
2016年 | 30篇 |
2015年 | 39篇 |
2014年 | 46篇 |
2013年 | 71篇 |
2012年 | 51篇 |
2011年 | 48篇 |
2010年 | 58篇 |
2009年 | 94篇 |
2008年 | 64篇 |
2007年 | 73篇 |
2006年 | 60篇 |
2005年 | 52篇 |
2004年 | 45篇 |
2003年 | 44篇 |
2002年 | 31篇 |
2001年 | 21篇 |
2000年 | 24篇 |
1999年 | 31篇 |
1998年 | 101篇 |
1997年 | 118篇 |
1996年 | 112篇 |
1995年 | 77篇 |
1994年 | 83篇 |
1993年 | 100篇 |
1992年 | 18篇 |
1991年 | 18篇 |
1990年 | 21篇 |
1989年 | 45篇 |
1988年 | 42篇 |
1987年 | 28篇 |
1986年 | 33篇 |
1985年 | 32篇 |
1984年 | 19篇 |
1983年 | 15篇 |
1982年 | 19篇 |
1981年 | 34篇 |
1980年 | 21篇 |
1979年 | 9篇 |
1978年 | 8篇 |
1977年 | 21篇 |
1976年 | 19篇 |
1975年 | 7篇 |
1970年 | 1篇 |
排序方式: 共有2047条查询结果,搜索用时 15 毫秒
41.
Neuropeptide Y Attenuates Stress‐Induced Bone Loss Through Suppression of Noradrenaline Circuits 下载免费PDF全文
PA Baldock S Lin L Zhang T Karl Y Shi F Driessler A Zengin B Hörmer NJ Lee IPL Wong EJD Lin RF Enriquez B Stehrer MJ During E Yulyaningsih S Zolotukhin ST Ruohonen E Savontaus A Sainsbury H Herzog 《Journal of bone and mineral research》2014,29(10):2238-2249
Chronic stress and depression have adverse consequences on many organ systems, including the skeleton, but the mechanisms underlying stress‐induced bone loss remain unclear. Here we demonstrate that neuropeptide Y (NPY), centrally and peripherally, plays a critical role in protecting against stress‐induced bone loss. Mice lacking the anxiolytic factor NPY exhibit more anxious behavior and elevated corticosterone levels. Additionally, following a 6‐week restraint, or cold‐stress protocol, Npy‐null mice exhibit three‐fold greater bone loss compared to wild‐type mice, owing to suppression of osteoblast activity. This stress‐protective NPY pathway acts specifically through Y2 receptors. Centrally, Y2 receptors suppress corticotropin‐releasing factor expression and inhibit activation of noradrenergic neurons in the paraventricular nucleus. In the periphery, they act to control noradrenaline release from sympathetic neurons. Specific deletion of arcuate Y2 receptors recapitulates the Npy‐null stress response, coincident with elevated serum noradrenaline. Importantly, specific reintroduction of NPY solely in noradrenergic neurons of otherwise Npy‐null mice blocks the increase in circulating noradrenaline and the stress‐induced bone loss. Thus, NPY protects against excessive stress‐induced bone loss, through Y2 receptor‐mediated modulation of central and peripheral noradrenergic neurons. © 2014 American Society for Bone and Mineral Research. 相似文献
42.
Cardoso AA; Schultze JL; Boussiotis VA; Freeman GJ; Seamon MJ; Laszlo S; Billet A; Sallan SE; Gribben JG; Nadler LM 《Blood》1996,88(1):41-48
Even if neoplastic cells express tumor associated antigens they still may fail to function as antigen presenting cells (APC) if they lack expression of one or more molecules critical for the induction of productive immunity. These cellular defects can be repaired by physiologic activation, transfection, or fusion of tumor cells with professional APC. Although such defects can be repaired, antitumor specific T cells may still fail to respond in vivo if they may have been tolerized. Here, human pre-B cell acute lymphoblastic leukemia (pre-B ALL) was used as a model to determine if primary human tumor cells can function as alloantigen presenting cells (alloAPC) or alternatively whether they induce anergy. In the present report, we show that pre-B cell ALL express alloantigen and adhesion molecules but uniformly lack B7-1 (CD80) and only a subset express B7-2 (CD86). Pre-B ALL cells are inefficient or ineffective alloAPC and those cases that lack expression of B7-1 and B7-2 also induce alloantigen specific T- cell unresponsiveness. Under these circumstances, T-cell unresponsiveness could be prevented by physiologic activation of tumor cells via CD40, cross-linking CD28, or signaling through the common gamma chain of the interleukin-2 receptor on T cells. Taken together, these results suggest that pre-B ALL may be incapable of inducing clinically significant T-cell-mediated antileukemia responses. This defect may be not only due to their inability to function as APC, but also due to their potential to induce tolerance. Attempts to induce clinically significant antitumor immune responses may then require not only mechanisms to repair the antigen presenting capacity of the tumor cells, but also reversal of tolerance. 相似文献
43.
High incidence of monoclonal proteins in the serum and urine of chronic lymphocytic leukemia patients 总被引:2,自引:0,他引:2
Chronic lymphocytic leukemia (CLL) is generally considered a nonsecretory B cell immunoproliferative disorder. Conventional electrophoretic and immunoelectrophoretic methods have revealed serum monoclonal proteins in less than 10% of these patients. However, there is increasing experimental evidence from in vitro studies demonstrating that CLL cells may secrete immunoglobulins, particularly free light chains. We examined the serum and urine of 36 consecutive CLL patients for monoclonal proteins using sensitive immunochemical methods (high resolution agarose gel electrophoresis combined with immunofixation). The results obtained were correlated with the Rai stage, quantitative immunoglobulin levels, and lymphocyte membrane immunoglobulin phenotype of the leukemic cells. Twenty-three monoclonal proteins were identified in the serum or urine of 22 patients, an incidence of 61%. Six patients had serum monoclonal proteins, seven had only urinary monoclonal proteins, and nine had monoclonal proteins in serum and urine. In every instance the monoclonal protein was the same light chain type as expressed on the leukemic cells. Our findings suggest that the monoclonal proteins observed in the serum or urine of CLL patients are secretory products of the tumor cells and that their discovery is a function of the sensitivity of the method used for their detection. 相似文献
44.
Interferon-alpha stimulates production of interleukin-10 in activated CD4+ T cells and monocytes 总被引:4,自引:1,他引:4
Aman MJ; Tretter T; Eisenbeis I; Bug G; Decker T; Aulitzky WE; Tilg H; Huber C; Peschel C 《Blood》1996,87(11):4731-4736
In the present study, we investigated the effect of interferon-alpha (IFN-alpha) on the expression of interleukin-10 (IL-10) mRNA and protein synthesis in human monocytes and CD4+ T cells. In mononuclear cells, IFN-alpha induced expression of IL-10 mRNA and further enhanced lipopolysaccharide (LPS)-stimulated IL-10 expression. In purified monocytes, a strong expression of IL-10 mRNA induced by LPS was not further enhanced by IFN-alpha. In highly purified CD4+ T cells, IFN- alpha upregulated IL-10 mRNA upon activation with phytohemagglutinin and phorbol myristate acetate. In purified monocytes, an effect of IFN- alpha on IL-10 protein synthesis was dependent on costimulation with LPS. Maximal stimulation of IL-10 protein by IFN-alpha was seen after prolonged incubation periods of 48 to 96 hours, whereas IFN-gamma reduced IL-10 production in the early incubation period. Similar effects of IFN-alpha were observed in CD4+ T cells activated with CD3 and CD28 monoclonal antibodies. Addition of IFN-alpha caused an increase of IL-10 in culture supernatants of activated T-helper cells of more than 100% after 96 hours of incubation. In contrast, other cytokines, including IFN-gamma and IL-4, had no influence on IL-10 secretion stimulated by CD3 and CD28 in CD4+ T cells. In serum samples of IFN-alpha-treated individuals, we failed to detect an influence of cytokine treatment on IL-10 serum levels, confirming the requirement of additional activating signals for IFN-alpha-mediated effects on IL-10 synthesis. In conclusion, IFN-alpha enhances the late induction of IL- 10, which physiologically occurs upon stimulation of monocytes and T cells. Biologically, this effect might enhance the negative-feedback mechanism ascribed to IL-10, which limits inflammatory reactions. 相似文献
45.
46.
Balla Sudheer B. Ankisetti Srikanth Aryasri Bushra Anjum Bolloju Vimal Bharathi Mir Mujahed Ali Kanaparthi Alekhya Buddhavarapu Sai Shravani 《International journal of legal medicine》2020,134(2):769-774
International Journal of Legal Medicine - Forensic age estimation, after completion of third molar mineralization, regressive features such as apposition of secondary dentin, which is seen as... 相似文献
47.
48.
49.
S. Harish P. Bharathi Prachi Prasad R. Ramesh S. Ponnusamy M. Shimomura J. Archana M. Navaneethan 《RSC advances》2021,11(31):19283
In the past few decades, air and water pollution by organic dyes has become a serious concern due to their high toxicity. Removal of these organic dyes from polluted water bodies is a serious environmental concern and the development of new advanced photocatalytic materials for decomposing organic dyes can be a good solution. In this work, layered molybdenum disulfide/nickel disulfide (MoS2/NiS2) nanocomposites with various NiS2 content was synthesized by a one-step hydrothermal method using citric acid as a reducing agent. The X-ray diffraction pattern shows the hexagonal and cubical crystal structure of MoS2 and NiS2, respectively. Morphological analysis confirms the formation of MoS2/NiS2 nanosheets. The elemental composition of the samples was carried out by XPS, which shows a significant interaction between NiS2 and MoS2. The photocatalytic performance of MoS2/NiS2 nanocomposites was studied by the degradation of rhodamine B (RhB). Ni-4 sample shows higher photocatalytic activity with a maximum degradation of 90.61% under visible light irradiation for 32 min.The photocatalytic performance of MoS2/NiS2 nanocomposites was studied by the degradation of rhodamine B (RhB). Ni-4 sample shows higher photocatalytic activity with a maximum degradation of 90.61% under visible light irradiation for 32 min. 相似文献
50.
目的 与开腹胆囊切除术相比,腹腔镜胆囊切除术(LC)有减少术后不适和较少的创作,但仍有改进的余地。方法:为进一步减轻手术创伤,我们引进了针式腹间胆囊切除术,共29例。结果 平均手术时间为75分钟,19例当天出院,10例隔天出院,其中1例是胆总管探查。结论 针式航空 镜胆囊切除术是一种可靠的技术。 相似文献