全文获取类型
收费全文 | 214515篇 |
免费 | 29249篇 |
国内免费 | 7194篇 |
专业分类
耳鼻咽喉 | 1706篇 |
儿科学 | 1893篇 |
妇产科学 | 5287篇 |
基础医学 | 16339篇 |
口腔科学 | 2172篇 |
临床医学 | 17464篇 |
内科学 | 19398篇 |
皮肤病学 | 1438篇 |
神经病学 | 727篇 |
特种医学 | 6696篇 |
外国民族医学 | 272篇 |
外科学 | 30552篇 |
综合类 | 28029篇 |
现状与发展 | 39篇 |
一般理论 | 3篇 |
预防医学 | 10333篇 |
眼科学 | 129篇 |
药学 | 14663篇 |
147篇 | |
中国医学 | 5011篇 |
肿瘤学 | 88660篇 |
出版年
2024年 | 543篇 |
2023年 | 4302篇 |
2022年 | 7922篇 |
2021年 | 11649篇 |
2020年 | 10833篇 |
2019年 | 9832篇 |
2018年 | 9365篇 |
2017年 | 9857篇 |
2016年 | 10616篇 |
2015年 | 12205篇 |
2014年 | 17574篇 |
2013年 | 17340篇 |
2012年 | 14045篇 |
2011年 | 14296篇 |
2010年 | 10384篇 |
2009年 | 10589篇 |
2008年 | 10832篇 |
2007年 | 10278篇 |
2006年 | 9109篇 |
2005年 | 7509篇 |
2004年 | 6167篇 |
2003年 | 5200篇 |
2002年 | 4378篇 |
2001年 | 4019篇 |
2000年 | 3308篇 |
1999年 | 2812篇 |
1998年 | 2364篇 |
1997年 | 2096篇 |
1996年 | 1715篇 |
1995年 | 1584篇 |
1994年 | 1280篇 |
1993年 | 994篇 |
1992年 | 862篇 |
1991年 | 800篇 |
1990年 | 589篇 |
1989年 | 546篇 |
1988年 | 462篇 |
1987年 | 407篇 |
1986年 | 318篇 |
1985年 | 401篇 |
1984年 | 330篇 |
1983年 | 222篇 |
1982年 | 233篇 |
1981年 | 217篇 |
1980年 | 176篇 |
1979年 | 129篇 |
1978年 | 89篇 |
1977年 | 62篇 |
1976年 | 58篇 |
1975年 | 33篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
951.
Mortality in police and firefighters in New Jersey 总被引:5,自引:0,他引:5
A proportionate mortality study of police and firefighters in New Jersey was conducted using the records of a comprehensive retirement system. Three reference populations were used: U.S. general population, New Jersey general population, and police as a reference group for the firefighters. Overall neither group differed from the New Jersey male population in the cause of death. Analyses by latency showed an increase in skin cancer and cirrhosis in firefighters and cirrhosis in police. With increased time from first employment, an inverse association was found between heart disease and time of first exposure. This was reflected in statistically significant increased proportionate mortality rates (PMR) for arteriosclerotic heart disease (ASHD) (ICD 410-414) for both working police (PMR = 1.15) and firefighters (PMR = 1.2). Retired police and firefighters had PMRs of 0.96 and 0.98, respectively. Firefighters had a significant increase in nonmalignant respiratory disease (PMR = 1.98) and leukemia (PMR = 2.76) when the police were used as a reference group. Potential causes of the above findings are discussed. 相似文献
952.
Previous studies have shown that oestrogen receptor content in breast cancer was correlated with qualitative and also, more strongly, with quantitative nuclear features in tissue sections. However, even with the better reproducible quantitative microscopical assessments, the variance in the correlation with oestrogen receptor was considerable. This might be due to the implicit problems of oestrogen receptor determination with the biochemical assay. Therefore, receptor content was studied using monoclonal antibodies in 50 consecutive invasive ductal breast cancers. Oestrogen receptor status was compared with qualitative features and with the mean and standard deviation of the nuclear area, morphometrically evaluated on immunostained and adjacent haematoxylin and eosin stained sections. In agreement with earlier observations, nearly all tumours with prominent elastosis were oestrogen receptor positive; but a minority of negative cases also showed elastosis. The correlation between the other qualitative features and receptor status was weak. A significant inverse correlation (P less than 0.001) existed between the receptor status and the mean and standard deviation of the nuclear area. Even with the highly reproducible morphometrical analysis, correlation between nuclear oestrogen receptor content and quantitative nuclear features was relatively weak. This might indicate that receptor status and nuclear morphometric features reflect different biological characteristics of breast cancers. 相似文献
953.
本文通过分析近5年来我院18例女性直肠癌全直肠系膜切除术后直肠阴道痿的临床资料。发现直肠阴道痿多发生于中低位直肠癌行全直肠系膜切除保肛手术的患者。痿的发生与肿瘤的位置、肿瘤的分期、肿瘤距肛门口的距离.以及手术技巧、手术难度、引流方法有关。而与是否进行预防性造口,以及是否采用腹腔镜手术无关。预防上强调应重视术中直肠前壁的锐性分离、结肠直肠吻合以及术后盆腔的负压引流。治疗上应首先进行保守治疗,即肠内营养,阴道冲洗。早期配合肠外营养、及全身或局部抗炎治疗,大部分直肠阴道痿通过保守治疗可以治愈。保守治疗无效时考虑结肠或回肠末端造口。若长期不愈应考虑吻合口肿瘤复发的可能。 相似文献
954.
目的
观察环氧化酶-2(cyclooxygenase-2,COX-2)选择性抑制剂塞来昔布对化学致癌剂7,12-二甲基苯蒽(7,12-dimethybenz[a]anthracene,DMBA)化学诱发的大鼠乳腺癌的抑制作用并探讨其机制.方法
将DMBA油剂灌胃复制大鼠乳腺癌模型,大鼠分为对照组(24只)和实验组(25只),观察塞来昔布对大鼠乳腺癌的抑制作用,并采用基因芯片技术了解治疗后2组肿瘤的基因表达谱差异.结果
实验组塞来昔布处理后乳腺肿瘤的数目、直径、体积分别为(2.56±1.26)个、(1.162±0.355)cm、(1.967±1.725)cm.;明显小于实验前的(3.40±1.22)个、(1.948±0.481)cm、(8.794±6.389)cm3;明显小于对照组(3.88±1.73)个、(2.231±0.736)cm、(10.268±5.447)cm3,差异有显著性意义(均P<0.01).对照组COX一2蛋白表达为62.5%(15/24),实验组COX-2蛋白表达为36.0%(9/25),差异有显著性意义(P<O.05).基因表达谱显示两组之间表达丰度差异2倍及以上的基因共有243条,其中表达上调2倍或以上的基因片段124条,表达下调2倍或以上的基因片段119条,发现功能不明的新基因6条,其中表达上调的4条.结论
塞来昔布能抑制DMBA诱发的大鼠乳腺癌进展,其机制和多种基因改变有关. 相似文献
955.
H. B. Reith W. Kozuschek L. W. Traverso 《Langenbeck's archives of surgery / Deutsche Gesellschaft fur Chirurgie》1996,381(4):207-211
Zusammenfassung Die Pankreaskopfresektion in der Modifikation nach Traverso-Longmire, mit Erhaltung eines funktionierenden Pylorus, hat gegenüber der Kausch-Whipple-Operation die Vorteile, daß Anastomosenulzera vermieden werden und daß die Patienten postoperativ eine bessere und schnellere Gewichtszunahme haben. Indikationen waren bisher die Papillenkarzinome und periampulare Tumoren. Bei den Adenokarzinomen lassen sich mit der Pyloruserhaltung gleich gute Überlebensraten erzielen. Unsere Ergebnisse von 56 Pyloruserhaltungen, davon 32 beim duktalen Karzinom und 28 Kausch-Whipple-Operationen in den Jahren von 1985–1993, belegen gleiche Überlebensraten, wie dies bereits für das Papillenkarzinom gezeigt werden konnte. Die Überlebenskurven zeigen, daß die Radikalität nicht von der Magenteilentfernung, sondern von der Resektion an den posterioren und retroperitonealen Resektionsrändern abhängt.
Current indications for pylorus preservation in duodenopancreatic head resection in malignancies
The Whipple procedure has been improved by preservation of a functioning pylorus. A functioning pylorus is important because marginal ulceration is avoided and, compared to the standard Whipple procedure with gastric resection, more patients can gain weight postoperatively. The most common indications are carcinomas of ampulla of Vater and periampullary tumors. In patients with pancreatic adenocarcinoma the pylorus-preserving variety results in equal or better survival rates. In 56 patients with pylorus preservation, 32 with ductal carcinoma, and 28 with Kausch-Whipple between 1985 and 1993, our results showed slightly better survival rates and better post-operative nutrition. The weakest aspect of the radical resection addresses the retroperitoneal margin of the pancreas head and not the gastric resection.相似文献
956.
Seiji Nakata Jin Sato Kyoichi Imai Hidetoshi Yamanaka Yoshio Ichinose 《International journal of urology》1995,2(3):191-197
Background Prostate cancer is rare in Asia, but the number of patients is increasing in Japan. We conducted an epidemiological study of prostate cancer in Gunma Prefecture, Japan, to investigate the trends and characteristics of the disease.
Methods: The subjects were 1.411 prostate cancer patients newly diagnosed between 1985 and and 656 patients who died from prostate cancer between 1981 and 1992. The incidence and mortality rates were calculated by year, demographic region and age.
Results: The yearly incidence rate showed an increase but the mortality rate showed no marked fluctuations. There was no significant difference between urban and ruraI districts in either incidence or mortality rate. The incidence rate tended to be high in the northern part of the prefecture, but no marked variation in mortality rate was seen. The incidence and mortality rates in districts with a history of manganese mining were high compared to those in districts without mining. In contrast, the incidence and mortality rates in districts with a history of zinc mining were comparatively lower. Both incidence and mortality rates showed a marked increase with age. The age-specific incidence showed a double logarithmic relationship to age.
Conclusions: The increase of the yearly incidence rate might be due to changes in lifestyle and environmental factors, improved diagnostic techniques, and increased awareness among the general public regarding prostate disease. Further investigation is needed to clarify the pattern and the causes of regional differences in the incidence and mortality rates. The possibilities that manganese and zinc might be related to prostatic carcinogenesis are suggested. Int J Urol 1995:2:191–197 相似文献
Methods: The subjects were 1.411 prostate cancer patients newly diagnosed between 1985 and and 656 patients who died from prostate cancer between 1981 and 1992. The incidence and mortality rates were calculated by year, demographic region and age.
Results: The yearly incidence rate showed an increase but the mortality rate showed no marked fluctuations. There was no significant difference between urban and ruraI districts in either incidence or mortality rate. The incidence rate tended to be high in the northern part of the prefecture, but no marked variation in mortality rate was seen. The incidence and mortality rates in districts with a history of manganese mining were high compared to those in districts without mining. In contrast, the incidence and mortality rates in districts with a history of zinc mining were comparatively lower. Both incidence and mortality rates showed a marked increase with age. The age-specific incidence showed a double logarithmic relationship to age.
Conclusions: The increase of the yearly incidence rate might be due to changes in lifestyle and environmental factors, improved diagnostic techniques, and increased awareness among the general public regarding prostate disease. Further investigation is needed to clarify the pattern and the causes of regional differences in the incidence and mortality rates. The possibilities that manganese and zinc might be related to prostatic carcinogenesis are suggested. Int J Urol 1995:2:191–197 相似文献
957.
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
958.
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
959.
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
960.
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