全文获取类型
收费全文 | 222193篇 |
免费 | 29659篇 |
国内免费 | 7095篇 |
专业分类
耳鼻咽喉 | 1761篇 |
儿科学 | 2042篇 |
妇产科学 | 5505篇 |
基础医学 | 15622篇 |
口腔科学 | 2894篇 |
临床医学 | 19025篇 |
内科学 | 22989篇 |
皮肤病学 | 1743篇 |
神经病学 | 1517篇 |
特种医学 | 6400篇 |
外国民族医学 | 253篇 |
外科学 | 29858篇 |
综合类 | 27837篇 |
现状与发展 | 44篇 |
一般理论 | 3篇 |
预防医学 | 14348篇 |
眼科学 | 410篇 |
药学 | 15611篇 |
152篇 | |
中国医学 | 5454篇 |
肿瘤学 | 85479篇 |
出版年
2024年 | 571篇 |
2023年 | 4567篇 |
2022年 | 8344篇 |
2021年 | 12107篇 |
2020年 | 11522篇 |
2019年 | 10263篇 |
2018年 | 9875篇 |
2017年 | 10182篇 |
2016年 | 10886篇 |
2015年 | 12408篇 |
2014年 | 18164篇 |
2013年 | 18618篇 |
2012年 | 14368篇 |
2011年 | 14646篇 |
2010年 | 10765篇 |
2009年 | 10906篇 |
2008年 | 11165篇 |
2007年 | 10485篇 |
2006年 | 9340篇 |
2005年 | 7589篇 |
2004年 | 6310篇 |
2003年 | 5263篇 |
2002年 | 4469篇 |
2001年 | 4032篇 |
2000年 | 3320篇 |
1999年 | 2866篇 |
1998年 | 2395篇 |
1997年 | 2081篇 |
1996年 | 1732篇 |
1995年 | 1584篇 |
1994年 | 1272篇 |
1993年 | 1020篇 |
1992年 | 869篇 |
1991年 | 779篇 |
1990年 | 590篇 |
1989年 | 544篇 |
1988年 | 470篇 |
1987年 | 400篇 |
1986年 | 308篇 |
1985年 | 387篇 |
1984年 | 316篇 |
1983年 | 214篇 |
1982年 | 209篇 |
1981年 | 203篇 |
1980年 | 171篇 |
1979年 | 115篇 |
1978年 | 74篇 |
1977年 | 63篇 |
1976年 | 57篇 |
1975年 | 34篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
991.
Are cytokines possible mediators of cancer cachexia? 总被引:1,自引:0,他引:1
Yoshikazu Noguchi Takaki Yoshikawa Akihiko Matsumoto Gösta Svaninger Johan Gelin 《Surgery today》1996,26(7):467-475
The possible role of cytokines in the development of cancer cachexia was reviewed from the literature. Tumor necrosis factor (TNF)-alpha, interleukin (IL)-1, IL-6, interferon (IFN)-gamma and leukemia inhibitory factor (LIF) can elicit many but not all host changes seen in cancer cachexia, including loss of appetite, loss of body weight, and the induction of acute-phase protein synthesis. However, these cytokines are not always demonstrated in the circulation of the cancer patients. The inability to detect circulating cytokines may be due to their low rate of production, their short half-life and rapid clearance from plasma, or their mode of action (autocrine or paracrine). Different cytokines are induced to stimulate the same response. This is very different from hormonal regulation, where a hormone acts on a cell directly through a specific receptor without depending on other mediators. Specific antibodies including anti-IFN-gamma, anti-TNF and anti-IL-6 antibodies, as well as the cyclooxygenase inhibitor indomethacin, have been used to reverse cancer cachexia. Overlapping physiologic activities make it unlikely that a single substance is the sole cause of cancer cachexia. It is hoped that further investigation on other cytokines and their possible relationships with hormones will help to clarify the mechanisms of cancer cachexia in the near future.This work was supported by a grant from the Japan-Sweden Foundation in 1991. 相似文献
992.
The irregular shape or contour of the patient’s surface in the treatment field can alter the dose distribution resulting in non-uniformity of dose in the treatment volume. Missing tissue compensators have been most commonly used to improve this non-uniformity, especially in head & neck, breast, lung and supraclavicular regions. Two or three dimensional compensators have been typically designed to make the dose uniform at a specific depth. This compensation shifts the dose distribution within the treatment volume so that some structures may be under or over compensated. This study will examine how various sites in head and neck cases are affected by compensators. We have also analyzed the uncertainty in compensated dose due to the daily variations in patient repositioning. Computer isodose plans using Cobalt-60 gamma rays and 6 and 18 MV x-rays were generated using coronal contours. Results show that the dose uniformity is improved for the treatment sites, especially for the thinner sites, like the larynx and the anterior cervical neck nodes. Finally, patient movement or positioning errors of ±1.0 cm will cause a change in dose distribution. 相似文献
993.
作者调查了湖南省4个有色金属矿,在1976-1981年间测定的井下平均氡子体浓度为现行限值的2-13倍,最高424倍;进行回顾性流行病学调查,其观察48125人年,肺癌PMR1.43-3.33,SMR3.46-11.50,氡致肺癌的相对危险增加系数每WLM为).010-0.057。矿上同时暴露于含砷矿尘,部分3.46-11.50,氡致肺癌的相对危险增加系数每WLM为0.010-0.057。矿上同… 相似文献
994.
目的:为了解食管癌患者和非食管癌患者体内维生素A的水平及其与食管癌发病的关系.方法:采用微量荧光法对32例食管癌患者(实验组)和32例非食管癌患者(对照组)血清中维生素A含量进行了测定.结果:显示实验组与对照组血清维生素A均值分别为1.55μmol/L,1.69μmol/L.经统计学处理两组血清维生素A水平有显著性差异(P<0.01).结论:提示食管癌的发生可能与机体维生素A水平有关,这种关系需进一步探讨. 相似文献
995.
996.
Matrix Metalloproteinases in Breast Cancer 总被引:1,自引:0,他引:1
Abstract: Matrix metalloproteinases (MMPs) represent a class of enzymes able to degrade numerous extracellular matrix macromolecules facilitating tumor invasion and metastasis. The principal MMPs involved in breast pathology are analyzed with their various roles and functions: gelatinases A and B, stromelysin-3, collagenase-3, and MT-MMP1 (membrane type MMP). In vivo and in vitro studies clearly demonstrate an important cooperation between tumor and stromal cells for the expression of these MMPs in breast carcinomas. The large expression of MMPs plead in favor of a major role of these enzymes in breast carcinoma progression and their detection may be used in some cases as a prognostic indicator. Studies now are in progress, directed toward the modulation of these MMPs and their inhibitors with new therapeutic agents to block tumoral invasion and metastasis due to these enzymes.? 相似文献
997.
Hiroshi Shimada Masao Nanko Shoichi Fujii Hidenobu Masui Shinji Togo Hideyuki Ike Akira Nakano Shigeo Ohki 《Journal of Hepato-Biliary-Pancreatic Surgery》1995,2(2):116-121
Hepatic micrometastases of the parenchyma adjacent to a macroscopic lesion were detected in 17 of 31 resected liver metastases.
Fifty-nine micrometastatic lesions were detected in total; 26 lesions were situated in the portal vein (PV), 22 in the central
vein (CV), 5 in the bile duct (BD), and 6 in the sinusoid (SS). A histological study confirmed the direct invasion of the
macrometastatic cancer cells into the adjacent PV, CV, BD, and SS. According to the tumor doubling time, the mean diameter
of the macrometastases in 19 remnant livers was calculated to have been 0.57±0.87 cm at the time of the primary resection.
The calculated diameter of 3 of these 19 macrometastases was found to be less than 0.01 cm, the minimum implantable size,
indicating that the cancer recurrence in these specimens may have developed from macroscopic metastatic lesions as a satellite,
and not from the primary tumor. In 13 patients who received doses of 5250 mg or more of 5 fluorouracil (FU) via the hepatic
artery, the cumulative disease-free rate 2 years postoperatively was 100%; this value was 47.6% in 11 patients who received
less than 5250 mg of 5 FU via the hepatic artery, and 0% in 39 patients who received no chemotherapy (P<0.005). These results suggest that anatomical hepatic resection for satellite lesions, combined with prophylactic hepatic
arterial chemotherapy for micrometastases, decreases the recurrence rate of hepatic metastases in the remnant liver. 相似文献
998.
999.
本文报道脑梗塞患者156例,就其发病情况,诱发因素,临床特点,治疗及预防进行了分析讨论。脑梗塞的发病高于脑出血,高血压动脉硬化是发生脑梗塞的主要危险因素。积极预防和治疗高血压有极其重要的意义。脑梗塞的治疗应根据脑水肿的情况进行,不宜普遍首先应用扩血管治疗。本病复发率高,反复发作可引起广泛性脑部损害,其病死率、病残率明显高于首次发病。小剂量阿斯匹林等药物应用对预防复发可能有一定作用。 相似文献
1000.
目的:研究进展期胃癌患者外周血T细胞免疫功能状态,手术对T细胞免疫功能的影响,以及对术后免疫治疗的指导。方法:采用间接免疫荧光染色流式细胞仪检测法,对43例进展期胃癌患者作手术前后外周血T细胞及亚群的测定,17例健康人作术前正常对照组。结果:与对照组相比,术前患者CD_3~+、CD_4~+细胞及CD_4~+/CD_8~+比值显著减少(P<0.01),而CD_8~+细胞无差异(P>0.05)。9例行非根治术者,手术前后T细胞及亚群无明显变化;而34例行根治术者,术后除CD_8~+细胞无变化外,CD_3~+、CD_4~+细胞及CD_4~+/CD_8~+比值均较术前有显著提高(P<0.01或P<0.05)。结论:术前进展期胃癌患者外周血T细胞免疫功能低下,行根治性切除术后得以改善。术后辅助免疫治疗或免疫化疗,以期提高生存率。 相似文献