全文获取类型
收费全文 | 27127篇 |
免费 | 2513篇 |
国内免费 | 2189篇 |
专业分类
耳鼻咽喉 | 228篇 |
儿科学 | 290篇 |
妇产科学 | 369篇 |
基础医学 | 3323篇 |
口腔科学 | 513篇 |
临床医学 | 3738篇 |
内科学 | 4087篇 |
皮肤病学 | 215篇 |
神经病学 | 1535篇 |
特种医学 | 1047篇 |
外国民族医学 | 14篇 |
外科学 | 2833篇 |
综合类 | 4417篇 |
现状与发展 | 8篇 |
一般理论 | 4篇 |
预防医学 | 1776篇 |
眼科学 | 621篇 |
药学 | 2947篇 |
15篇 | |
中国医学 | 1598篇 |
肿瘤学 | 2251篇 |
出版年
2024年 | 94篇 |
2023年 | 418篇 |
2022年 | 1086篇 |
2021年 | 1374篇 |
2020年 | 1031篇 |
2019年 | 928篇 |
2018年 | 885篇 |
2017年 | 897篇 |
2016年 | 779篇 |
2015年 | 1204篇 |
2014年 | 1584篇 |
2013年 | 1343篇 |
2012年 | 2039篇 |
2011年 | 2122篇 |
2010年 | 1411篇 |
2009年 | 1116篇 |
2008年 | 1543篇 |
2007年 | 1497篇 |
2006年 | 1409篇 |
2005年 | 1495篇 |
2004年 | 1003篇 |
2003年 | 956篇 |
2002年 | 755篇 |
2001年 | 608篇 |
2000年 | 653篇 |
1999年 | 655篇 |
1998年 | 428篇 |
1997年 | 384篇 |
1996年 | 325篇 |
1995年 | 312篇 |
1994年 | 276篇 |
1993年 | 181篇 |
1992年 | 204篇 |
1991年 | 171篇 |
1990年 | 138篇 |
1989年 | 99篇 |
1988年 | 103篇 |
1987年 | 76篇 |
1986年 | 77篇 |
1985年 | 52篇 |
1984年 | 34篇 |
1983年 | 28篇 |
1982年 | 12篇 |
1981年 | 9篇 |
1980年 | 8篇 |
1979年 | 10篇 |
1978年 | 3篇 |
1977年 | 4篇 |
1975年 | 2篇 |
1929年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
82.
Genetic imbalances in pleomorphic xanthoastrocytoma detected by comparative genomic hybridization and literature review. 总被引:2,自引:0,他引:2
Xiao-Lu Yin Angela Bik-Yu Hui Eleanore C Liong Min Ding Alex R Chang Ho-Keung Ng 《Cancer Genetics and Cytogenetics》2002,132(1):14-19
Pleomorphic xanthoastrocytoma (PXA) is a rare, low-grade astrocytic tumor found in the central nervous system. Histologically, the tumor is characterized by markedly pleomorphic and lipidized cells. Although most of the patients have a favorable prognosis, a small number of cases undergoing recurrence or progression to anaplastic astrocytoma were reported. Very few genetic studies have been performed on PXA because of its rarity and the pathogenesis of this neoplasm is largely unknown. In order to provide an overview of genetic alterations in PXA, we performed comparative genomic hybridization to identify chromosomal imbalances (DNA gains and losses) in three cases of PXA. Genetic imbalance was detected on at least one chromosome for each case. One case, which revealed multiple genetic alterations, showed a poor prognosis. DNA gain on chromosome 7 and loss on 8p were demonstrated in two of three cases, suggesting that the candidate gene(s) located on these regions may play a role in the development of PXA. Further studies are needed to identify the residing candidate genes that are involved in the tumorigenesis of PXA. In addition, the histopathological features and previous genetic studies on PXA are reviewed. 相似文献
83.
对12例经病理学专家会诊、从病变上认定的淋巴结“结节病”石蜡包埋组织,应用结核杆菌DNA特异性序列片段的聚合酶链反应(M.TB-PCR)技术、BCG免疫组化(BCG-IHC)技术和抗酸染色(AF)进行了分支杆菌/结核杆菌检测。在这12例考虑为“结节病”的病例中:有1例呈BCG-IHC和M。TB-PCR两项阳性;另1例呈AF、BCG-IHC和M.TB-PCR三项阳性。研究结果提示:(1)某些结核性淋巴结炎可呈结节病样病变;(2)淋巴结结节病很可能与分支杆菌/结核杆菌感染有关。 相似文献
84.
结核性淋巴结炎的组织细胞反应性增生变型 总被引:1,自引:0,他引:1
应用结核杆菌DNA123bp特异性序列片段为靶序列的多聚酶链反应(M·TB-PCR)技术、BCG免疫组化(BCG-IHC)技术和抗酸染色(AF)方法,对38例呈现组织细胞反应性增生-碎屑样坏死-嗜中性白细胞渗出病变的淋巴结石蜡包埋组织进行了分支杆菌/结核杆菌的回顾性检测。三种方法的综合阳性率为52.6%(20/38例)。AF、BCG-IHC和M·TB-PCR的各自阳性率分别为0.8%、26.3%和50%。研究结果表明:(1)在按本文标准选择的淋巴结“组织细胞反应性增生”病变中,有半数病例与结核杆菌的感染有关,即结核性淋巴结炎可呈现“组织细胞反应性增生”之类的变型;(2)PCR技术在结核性淋巴结炎的病原学诊断上具有重要价值。 相似文献
85.
以果蝇唾腺作为基质,用间接免疫荧光法检测血清抗果蝇唾腺染色体抗体[简称抗染色体抗体(Anti—chromosome antibody AchrA)]。正常人及其它风湿性疾病患者共151例,均为阴性,而系统性红斑狼疮(SLE)患者44例,AchrA阳性者占16例(36.4%)。揭示AchrA对SLE有高度特异性及一定的敏感性。对比SLE患者的AchrA及抗核抗体(ANA),双阳性占15例(34.1%),提示与两种抗体起反应的核成分不尽相同。 相似文献
86.
Fgl2 prothrombinase expression in mouse trophoblast and decidua triggers abortion but may be countered by OX-2 总被引:4,自引:0,他引:4
Spontaneous abortion of normal karyotype embryos in mice and in humans is associated with an increase in uterine T helper (Th) 1 type proinflammatory cytokines, tumour necrosis factor (TNF)-alpha, interferon-gamma and interleukin (IL)-1, and a deficiency of Th2/3 type cytokines, IL-4, IL-10, and transforming growth factor (TGF)-beta2. In mice, Th1 cytokines up-regulate a novel prothrombinase, fgl2, which via thrombin, leads to activation of polymorphonuclear leukocytes that terminate the pregnancy. Here we show that Th1 cytokines up-regulate fgl2 mRNA in fetal trophoblast and secondary decidua of CBA/JxDBA/2 and CBA/JxBALB/c matings, and promote fibrin deposition. This pattern is accompanied by a high rate of abortion. However, the spontaneous abortion rates in abortion-prone CBAxDBA/2 matings and in low abortion rate CBAxBALB/c matings were significantly lower than that expected from the frequency of implantations with high levels of fibrin and fgl2 mRNA(hi). As the glycoprotein OX-2 occurs in the pregnant rat uterus and can deviate cytokine responses to Th2/3, we investigated OX-2 in pregnant CBA/J mice. We found OX-2 mRNA was present at the same sites as fgl2 mRNA, but was reduced in response to Th1 cytokines. Furthermore, anti-OX-2 raised the abortion rate to predicted levels, while recombinant OX-2 dramatically reduced the abortion rate. Fgl2 prothrombinase may provide a mechanism explaining pregnancy loss, and conversely, successful pregnancy may be due in part to OX-2-dependent activation of maternal tolerance mechanisms at the feto-maternal interface. 相似文献
87.
目的:探讨高糖对体外培养Schwann细胞生长及细胞外信号调节激酶(ERK)磷酸化的影响.方法:按照培养液中葡萄糖浓度的小同,分为对照组与高糖组.用MTT法检测Schwann细胞生长情况;用ELISA法检测对照组与高糖组ERK1/2磷酸化的程度,以及加入神经源性一氧化氮合成酶(nNOS)抑制剂后ERK1/2磷酸化的程度.结果:高糖浓度下,细胞虽有增殖但幅度及时程明显低于对照组,高糖抑制Schwann细胞生长;随着精浓度的升高.ERK1/2磷酸化的程度逐渐增加,并与加入nNOS抑制剂有相似的表现.结论:高糖抑制Schwann细胞生长,并且降低nNOS的量,减弱一氧化氮(NO)对ERK1/2的抑制作用,导致ERK1/2磷酸化水平升高. 相似文献
88.
J A Ding H Hashimoto T Sugimoto M Tsuneyoshi M Enjoji 《Acta pathologica japonica》1990,40(10):744-754
Six cases of Bednar tumor were analyzed clinicopathologically along with a review of 39 published cases. The findings were then compared with data on 44 cases of ordinary dermatofibrosarcoma protuberans (DFSP) obtained from our files. The clinical manifestations of the patients and the anatomic locations of the tumors were similar between the two categories, but the rate of recurrence was lower in cases of Bednar tumor. The histologic pattern of Bednar tumor was indistinguishable from ordinary DFSP except for scattered melanosome-containing cells. Ultrastructural and immunohistochemical examinations showed no evidence of neuroectodermal differentiation of dominant spindle-shaped cells in Bednar tumor, supporting a fibroblastic line of differentiation. The origin and pathogenesis of the melanosome-containing cells were considered. These cells failed to react with HMB-45, a melanoma-specific antibody, and the large majority of melanosomes present were mature or at Stage IV, plus a few immature ones at Stage II. These pigmented cells do not appear to be neoplastic, and cannot be used as proof to indicate that Bednar tumor is a neuroectodermal neoplasm. 相似文献
89.
Ping Zhang Zhenhua Sun Guang Li Yugang Zhuang Mengxiam Ding Zhiliu Feng 《Macromolecular chemistry and physics.》1993,194(7):1871-1877
The structure and miscibility of polyimide PBPI-E/PTI-E blends were studied by wide- and small-angle X-ray scattering and dynamic mechanical analysis, where PBPI-E is a biphenyldianhydride-based polyimide, and PTI-E is a polyimide from 4,4′-thiodiphthalic anhydride and 4,4′-oxydianiline. The results obtained show that there exists a paracrystalline structure in the blends with high content of PBPI-E, but this does not affect the miscibility of the blends. The blends are miscible over the entire composition range, since only one Tg was observed for each blend. Meanwhile, the segregation of PTI-E during crystallization of PBPI-E in the blends is interlamellar. 相似文献
90.
经皮穿刺椎间盘髓核摘除术入路的研究 总被引:1,自引:0,他引:1
为提供椎间盘髓核摘除术形态学依据,在7具成人横断面标本上观察测量了L1~L5椎间盘平面经皮穿刺椎间盘髓核摘除术的进针点、角度和深度。发现在L1~L3、L4~L5椎间盘髓核的穿刺点以距后正中线8~10cm,9~11cm,穿刺角度以46.7°~59.5°,穿刺深度为110.2~128.9mm为最宜。 相似文献