全文获取类型
收费全文 | 80160篇 |
免费 | 7022篇 |
国内免费 | 4628篇 |
专业分类
耳鼻咽喉 | 940篇 |
儿科学 | 971篇 |
妇产科学 | 789篇 |
基础医学 | 9921篇 |
口腔科学 | 1385篇 |
临床医学 | 8824篇 |
内科学 | 11630篇 |
皮肤病学 | 1423篇 |
神经病学 | 3989篇 |
特种医学 | 3935篇 |
外国民族医学 | 21篇 |
外科学 | 8085篇 |
综合类 | 12363篇 |
现状与发展 | 28篇 |
一般理论 | 7篇 |
预防医学 | 5405篇 |
眼科学 | 2360篇 |
药学 | 8769篇 |
67篇 | |
中国医学 | 4048篇 |
肿瘤学 | 6850篇 |
出版年
2024年 | 201篇 |
2023年 | 1018篇 |
2022年 | 2554篇 |
2021年 | 3560篇 |
2020年 | 2552篇 |
2019年 | 2326篇 |
2018年 | 2496篇 |
2017年 | 2373篇 |
2016年 | 2501篇 |
2015年 | 3738篇 |
2014年 | 4615篇 |
2013年 | 4578篇 |
2012年 | 6687篇 |
2011年 | 7084篇 |
2010年 | 4672篇 |
2009年 | 4028篇 |
2008年 | 5024篇 |
2007年 | 4746篇 |
2006年 | 4471篇 |
2005年 | 3939篇 |
2004年 | 2998篇 |
2003年 | 2988篇 |
2002年 | 2498篇 |
2001年 | 1696篇 |
2000年 | 1428篇 |
1999年 | 1299篇 |
1998年 | 815篇 |
1997年 | 719篇 |
1996年 | 615篇 |
1995年 | 557篇 |
1994年 | 533篇 |
1993年 | 351篇 |
1992年 | 382篇 |
1991年 | 347篇 |
1990年 | 289篇 |
1989年 | 266篇 |
1988年 | 176篇 |
1987年 | 192篇 |
1986年 | 144篇 |
1985年 | 97篇 |
1984年 | 55篇 |
1983年 | 39篇 |
1982年 | 39篇 |
1981年 | 28篇 |
1980年 | 27篇 |
1979年 | 16篇 |
1978年 | 6篇 |
1975年 | 7篇 |
1973年 | 10篇 |
1972年 | 6篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
Kusumi T Nishikawa S Tanaka M Ogawa T Jin H Sato F Toh S Hasegawa T Kijima H 《Pathology international》2005,55(12):802-806
Low-grade fibromyxoid sarcoma (LGFMS) is a rare tumor. Reported herein is a case of LGFMS arising in the big toe. The patient was a 58-year-old man who underwent excision of the tumor. The tumor was well-demarcated. Histologically, there were proliferating spindle-shaped tumor cells arranged in a whorled growth pattern, and the stroma showed hyalinized collagen bundles and a myxoid matrix. Nuclear mitotic figures were conspicuous in part. A large rosette-like structure with hyalinized stroma was found, which is characteristic of LGFMS. The differential diagnosis included tumor occurrence in adults; tending to arise in distal extremities; and having bland fibromyxoid histological features, such as fibroma of tendon sheath, low-grade myxofibrosarcoma and acral myxoinflammatory fibroblastic sarcoma. It was not possible to detect the FUS/CREB3L2 and FUS/CREB3L1 fusion genes from the formalin-fixed and paraffin-embedded tissue, although the histological features of the present case were typical of LGFMS. LGFMS may become more common with time, and unique cases may accumulate. 相似文献
72.
Pathological changes of lung cancer in miners of Yunnan Tin Mine were studied, and additionally, mineral dust in the miners' lung were also investigated by using scanning electronic microscope, energy disperse X-ray spectrometer and electronic probe. The results showed: 1. mineral dust caused active hyperplasia, atypical hyperplasia, metaplasia and atypical metaplasia of the epithelial of alveoli and bronchi, which was able to induce cancer. 2. Pneumoconiosis-like changes in the miner's lung are correlated with the high incidence of lung cancer. 3. Correlated also with copper, lead, zinc and iron may be the high incidence of lung cancer. 4. Transition form from hyperplasia and atypical hyperplasia of alveolar epithelia to malignancy was observed. It suggests that lung squamous cell carcinoma probably originates from the alveolar epithelia of the lung. 相似文献
73.
Radiation proctitis is a frequent acute complication encountered with pelvic irradiation. This study was aimed at establishing the optimal radiation dose for radiation-induced proctitis in rats. Female Wistar rats were used. The rectal specimens were examined morphologically at 5th and 10th day following 10-30 Gy irradiation in single fraction. With increasing dose, mucosal damage became worse, and there was a prominent reaction after > or =15 Gy. We selected 17.5 Gy as an optimal dose for radiation proctitis and examined specimens at day 1-14 and at week 4, 6, 8, and 12 after 17.5 Gy. The rectal mucosa revealed characteristic histological changes with time. An edema in lamina propria started as early as 1-2 days after irradiation and progressed into acute inflammation. On day 7 and 8, regeneration was observed with or without ulcer. Four weeks later, all regeneration processes have been completed with end result of either fibrosis or normal appearing mucosa. This study showed that the radiation injury of the rectum in rat develops in dose-dependent manner as it has reported in previous studies and suggested that 17.5 Gy in single fraction is the optimum dose to evaluate the protective effect of various medications for radiation proctitis in face of the clinical situation. 相似文献
74.
本研究测定与肿瘤关系密切的微量元素Zn、Cu、Mn、Cr和Se在口腔颌面部正常者与良、恶性肿瘤患者血清中含量共91例。结果表明微量元素Zn、Cu、Mn、Cr和Se在口腔颌面部肿瘤与其它部位肿瘤一样有明显变化。用模式识别方法以微量元素作为指标,对良恶性肿瘤进行鉴别诊断,有一定的临床意义。 相似文献
75.
Possible changes in membrane lipid assemetry may result in altered function with aging. Membrane proteolysis is an additional factor which must be considered, both with respect to modulation of membrane function and also as a methodological problem in analyses of membrane dynamics. 相似文献
76.
Ranajit Chakraborty Ranjan Deka Li Jin Robert E. Ferrell 《American journal of human biology》1992,4(3):387-397
Because of their high degree of polymorphisms, the variable number of tandem repeat (VNTR) loci have become extremely useful in studies involving gene mapping, determination of identity and relatedness of individuals, and evolutionary relationships among populations. However, there are some concerns regarding whether or not the patterns of such genetic variation can be studied by the classical population models that are developed for studying genetic variation at blood groups and protein loci, since VNTR alleles detected by molecular size may not always be identical by descent. Although theoretical and empirical studies demonstrate that this concern is overstated, this study provides further support of the application of the traditional mutation-drift models to predict the pattern of intra- and inter-populational variation at VNTR loci. By comparing genetic variation at six VNTR loci with that at 16 blood groups and protein loci in three ethnically defined populations, we show that the patterns of variability at these two sets of loci are in general parallel to each other. Shared VNTR alleles among populations are generally more frequent than the ones which are not present in every population; the proportion of shared alleles among populations increases with increasing genetic similarity of populations; and the number of VNTR alleles is positively correlated with gene diversity at these loci. All of these observations are in agreement with the prediction of the mutation-drift models, particularly when the possibility of forward-backward mutations are taken into account. This parallelism of genetic variation at VNTR loci and blood groups/protein loci further asserts the potential of using such hypervariable loci for microevoltionary studies, where closely related populations may exhibit considerably less allele frequency differences at the classical blood group and protein loci. © 1992 Wiley-Liss, Inc. 相似文献
77.
冠脉内支架临床发展策略 总被引:1,自引:0,他引:1
董为人 《生物医学工程学杂志》1997,14(2):156-163
冠脉内支架是临床上预防PTCA并发症的有效措施,但金属支架固有的血栓菜成原性和对血管壁组织的永久性刺激可导致院内心脏事件和再狭窄。为解决上述问题,作者提出,血管内支架联合靶向药物传输离子照射或基因治疗、基因修饰的内皮细胞的种植支架、吱物可吸收缓释药物支架材料研制为临床冠脉内支架开辟了广阔的发展前景。 相似文献
78.
79.
We develop an integrated model of isolated rat arterial resistance vessel (RV), which can simulate its major property of myogenic response. The vascular smooth muscle cell is an important component of the wall of this vessel, and serves as a vasomotor organ providing the active tension generation that underlies the myogenic response of the wall to stretch. In the previous study, we focused on the development of a smooth muscle cell model that can mimic the strain-sensing and force-generating features of the myogenic mechanism. In the current model, we embed this cell model in a larger vessel wall configuration, and couple the time course of cellular contractile activation to macroscopic changes in vessel diameter. The integrated model is used to mimic published pressure-vessel diameter data obtained from isolated RVs that are mounted in a hydraulic test apparatus. The model provides biophysically based insights into the myogenic mechanism as it responds to changes in transmural pressure, in the presence and absence of Ca2+ blockers applied to the bathing fluid.It mimics measured data very well and provides a model that is able to link events at subcellular level to macroscopic changes in vessel diameter. The model initiates a mechanistic approach to investigate myogenic response, which has not been taken previously by any other models. 相似文献