全文获取类型
收费全文 | 64709篇 |
免费 | 5920篇 |
国内免费 | 4413篇 |
专业分类
耳鼻咽喉 | 455篇 |
儿科学 | 670篇 |
妇产科学 | 673篇 |
基础医学 | 7542篇 |
口腔科学 | 1257篇 |
临床医学 | 8562篇 |
内科学 | 9288篇 |
皮肤病学 | 605篇 |
神经病学 | 3358篇 |
特种医学 | 2307篇 |
外国民族医学 | 43篇 |
外科学 | 6518篇 |
综合类 | 11368篇 |
现状与发展 | 19篇 |
一般理论 | 2篇 |
预防医学 | 4316篇 |
眼科学 | 1960篇 |
药学 | 6981篇 |
45篇 | |
中国医学 | 3778篇 |
肿瘤学 | 5295篇 |
出版年
2024年 | 233篇 |
2023年 | 1083篇 |
2022年 | 2707篇 |
2021年 | 3562篇 |
2020年 | 2536篇 |
2019年 | 2091篇 |
2018年 | 2337篇 |
2017年 | 1993篇 |
2016年 | 1963篇 |
2015年 | 3052篇 |
2014年 | 3696篇 |
2013年 | 3137篇 |
2012年 | 4664篇 |
2011年 | 5219篇 |
2010年 | 3088篇 |
2009年 | 2564篇 |
2008年 | 3228篇 |
2007年 | 3248篇 |
2006年 | 3245篇 |
2005年 | 3206篇 |
2004年 | 2305篇 |
2003年 | 2252篇 |
2002年 | 1991篇 |
2001年 | 1612篇 |
2000年 | 1550篇 |
1999年 | 1503篇 |
1998年 | 969篇 |
1997年 | 907篇 |
1996年 | 696篇 |
1995年 | 654篇 |
1994年 | 555篇 |
1993年 | 349篇 |
1992年 | 462篇 |
1991年 | 372篇 |
1990年 | 344篇 |
1989年 | 288篇 |
1988年 | 271篇 |
1987年 | 213篇 |
1986年 | 179篇 |
1985年 | 156篇 |
1984年 | 74篇 |
1983年 | 60篇 |
1982年 | 34篇 |
1981年 | 28篇 |
1980年 | 26篇 |
1979年 | 42篇 |
1975年 | 28篇 |
1974年 | 32篇 |
1973年 | 28篇 |
1971年 | 24篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
乳腺病变X线立体定位钢丝置入移位的分析 总被引:1,自引:0,他引:1
目的分析乳腺立体定位下钢丝置入移位的表现、原因、处理方法,提高术前定位的准确性。方法行立体定位置入钢丝患者79例,96个病变,发生钢丝移位13例。结果立体定位中发生钢丝移位5例,原因分别来自于患者和操作医师;立体定位完成后钢丝移位5例,原因是局麻注射药物过多,导致乳腺Z轴的深度与计算机提示的实际深度不符合、放置定位针的方法不正确、拔出钢丝外套针套时疏忽钢丝是否已锚定病变。处理方法:可按照钢丝提示位置向病变方向移位2cm以内进行手术,重新放置第2根钢丝,将双J型钢丝收入针套并取出体外,重新定位。手术中钢丝脱出2例,因术后过分提拉钢丝所致,放射科医师放置钢丝后应向外科医师准确描述深度、方向,并从距离钢丝头端距离皮肤最近处取切口手术。术后标本未见钙化1例,与钙化位于手术电刀破坏的腺体内有关,可扩大范围切除并短期复查,证实钙化是否完整切除。结论正确认识乳腺X线立体定位下钢丝移位的表现,熟练掌握其处理方法,可提高对不可触及的乳腺病变的定位准确性,正确引导外科手术。 相似文献
62.
Matthias Peltz Tian-Teng He Glenn A Adams Robert Y Chao Michael E Jessen Dan M Meyer 《The Journal of heart and lung transplantation》2005,24(7):896-903
BACKGROUND: Lungs harvested for transplantation are stored while inflated with oxygen, which can serve to support oxidative metabolism. However, strategies aimed at increasing graft metabolism during storage have received little attention. In this study, we added pyruvate to the preservation solution Perfadex and measured the effects on oxidative metabolism and reperfusion lung function. METHODS: Rat lungs were stored for 6 and 24 hours in low-potassium dextran solution at 10 degrees C containing either 5 mmol/liter uniformly carbon-13 (U-(13)C) labeled glucose (Perfadex), 32 mmol/liter 3-(13)C pyruvate (pyruvate), or both (combined). Oxidation of exogenous substrates was measured as the incorporation of (13)C into tricarboxylic acid cycle intermediates by magnetic resonance spectroscopy. Additional groups of lungs with each substrate modification were preserved for 6 or 24 hours and then reperfused. RESULTS: Enrichment of tricarboxylic acid cycle intermediates was low in the Perfadex group (9% at 6 hours and 32% at 24 hours of storage, respectively). In contrast, enrichment was significantly increased in both the pyruvate group (50% and 59%, respectively) and combined group (39% and 54%, respectively) compared with the Perfadex group (p<0.01). Graft function was excellent after 6-hour storage in all groups. All lungs stored for 24 hours exhibited inferior lung function, but oxygenation, pulmonary artery pressures, and airway pressures in the combined group were significantly improved compared with the Perfadex group (p<0.05). CONCLUSIONS: Preservation solution substrate composition influences graft metabolism during storage. The addition of pyruvate to Perfadex increases metabolism during storage and improves reperfusion lung function. 相似文献
63.
Study of pathological morphology in chronic sinusitis] 总被引:1,自引:0,他引:1
OBJECTIVE: To study the pathological characteristics and regularity of chronic sinusitis (CS) in different clinical types, tc estimate the reliability and feasibility of CS classification on the pathologic basis. METHODS: HE, Van Gieson's, alcian blue-periodic acid-schiff(AB-PAS) staining was used to observe the changes of epithelium, to measure the thickness of basement membrane and the area of mucous glands. The ultrastructural changes of pseudostratified ciliated columnar epithelium were observed under transmission electron microscope (TEM) and scanning electron microscope (SEM). RESULTS: The epithelial fiber tissue was increased, the basement membrane was thickened, and the mucous glands were obviously increased in CS under the light microscope. Subepithelial fibrosis and thickened basement membrane were most obviously seen in type III of CS and the hyperplasia of mucous glands was most distinct in type II. Under the TEM, abnormal structure of cilia, decrease of ciliated cells, increase of goblet cells were detected in all three CS types. Under the SEM, the cilia of every types showed the ingravescenced process of pathological changes from slight cilium disorder, disorientation, to desquamation of most cilia and replacement of microvilli. CONCLUSION: There is significant distinction of mucous membrane structure among three types. The Chinese classification of CS has pathological basis, it represents the occurrence, development and regularity of CS, and it can be used as basis in further study, communication and evaluation for surgical effect of CS. 相似文献
64.
65.
根据桂枝汤的效应消除半衰期和表观消除半衰期制订给药方案的探讨 总被引:3,自引:0,他引:3
为探讨药效法估测的效应消除半衰期和效量法估测的表观半衰期对合理制订给药方案的意义和作用,以桂枝汤解热和抗炎的药物动力学实验中所得的相应参数值设计了给药方案,观察了它们在提高药效上的作用。结果表明在给药总剂量相等、首次给药同时开始的情况下,以半衰期设计的给药方案组的药效均明显高于习惯的一次给药组;而以效应消除半衰期设计给药方案组药效增强率又高于以表观半衰期设计的方案组。提示效应消除半衰期比表观半衰期似更有实践意义。 相似文献
66.
北京市东城区和平里社区居民慢性病防治探讨 总被引:3,自引:0,他引:3
王秀清 《中国慢性病预防与控制》1997,5(1):29-30,33
为探索慢性病的防治方法,我们于1989 ̄1994年社区居民中开展了以高血压为主的循环系统慢性病防治课题,经过5年的干预,观察组与对照组居民及接受管理的高血压病人在减少吸烟,饮酒,控制食盐摄入,掌握慢性病防治知识等方面有显著性差异,取得了满意的结果,从而为今后全面开展慢性病防治积累了经验。 相似文献
67.
本实验采用血管铸型扫描电镜,注射明胶卡红组织切片显微镜下观察和注射铅丹乳胶追踪血管来源三种方法对14只健康大白鼠肾上腺血管构筑进行了研究。大白鼠肾上腺动脉发自腹主动脉和肾动脉。它们在行程中发出分支至腺体表面,再次分支穿入囊内,逐级分支至毛细血管。皮质动脉发自囊内血管,它们在皮质中分支分布。球状带的毛细血管与囊的毛细血管相连,毛细血管在球状带围绕细胞团形成网眼状;在束状带呈放射状排列;在网状带吻合增多形成网状。髓质动脉亦发自囊的血管,它们在皮质中不发分支直抵髓质,在髓质分成毛细血管。网状带的毛细血管越向髓质口径越粗,它们在皮髓交界处互相吻合形成更粗的静脉,这些静脉逐级吻合,最后形成一主干——中央静脉,它穿出皮质出现于肾上腺门处。左侧的中央静脉注入在肾静脉,右侧的注入下腔静脉。 相似文献
68.
甘利欣联合654-2治疗慢性乙型肝炎60例疗效观察 总被引:2,自引:0,他引:2
目的观察甘利欣联合654-2治疗慢性乙型肝炎的临床疗效。方法采用甘利欣联合654-2治疗慢性乙型肝炎患者60例。治疗4w和8w时,分别观察临床症状、体征及肝功能(包括ALT和TB)的变化。结果ALT、TB恢复程度以治疗组为高,与对照组比较有统计学差异(P<0.05)。采用甘利欣联合654-2治疗8w后,总有效率为96.6%。结论甘利欣联合654-2治疗慢性乙型肝炎的治疗较疗效满意。 相似文献
69.
组织多肽特异性抗原在乳腺癌中的临床研究 总被引:16,自引:1,他引:15
Hang Zheng Ben-fu He Rong-cheng Luo Chang-xuan You Guo-feng Mai Hui-fang Lu 《第一军医大学学报》2003,23(8):823-825
OBJECTIVE: To investigate the expression of serum tissue polypeptide-specific antigen (TPS) in breast cancer patients and its clinical value in such cases. METHODS: Altogether 160 subjects (90 patients with breast cancer, 40 with benign breast lesions, and 30 healthy subjects) were enrolled in this study. The serum TPS and CA153 levels were measured by ELISA in all the subjects. RESULTS: The levels and positivity rate of serum TPS and CA153 in breast cancer group were significantly higher than those in the normal subjects group and benign lesion group (P<0.01), and became even higher as the malignancy progressed. High serum TPS level was detected in the cancer patients in stage I. Serum TPS level was the most sensitive to bone metastasis of the malignancy, but its highest levels occurred in cases of lymphoid node metastasis (P<0.05). In patients who responded favorably to the treatment, serum TPS and CA153 levels were significantly reduced (P<0.05), but the reduction in TPS levels tended to be more obvious (P<0.05). CONCLUSION: Serum TPS can be used as a very useful and sensitive tumor marker in the diagnosis of breast cancer, especially in case of bone metastasis, and may be of great value in clinical decision-making and assessment of therapeutic effect. 相似文献
70.
Jiang He Mary Rusckowski Yi Wang Shuping Dou Xinrong Liu Surong Zhang Guozheng Liu Donald J. Hnatowich 《Molecular imaging and biology》2007,9(1):17-23
Objective Pretargeting with radioactivity has significantly improved tumor to normal tissue radioactivity ratios over conventional antibody
imaging in both animal studies and clinical trials. This laboratory is investigating DNA analogues such as phosphorodiamidate
morpholinos (MORFs) for pretargeting using technetium-99m (99mTc) for detection. However, the unique properties of fluorescence activation and quenching combined with oligomers with their
unique properties of hybridization may be particularly useful when used together for pretargeting with optical detection.
The use of linear fluorophore-conjugated oligomer duplexes have been little used in animals, and to our knowledge, have not
previously been considered for pretargeting applications.
Methods A MORF/cDNA pair was selected such that when hybridized, the fluorescence of the Cy5.5-conjugated 25 mer MORF (Cy5.5–MORF25)
is inhibited with a BHQ3-conjugated 18 mer complementary DNA (BHQ3–cDNA18). The short BHQ3–cDNA18 was selected to dissociate
in the presence of a long cMORF25 in the pretargeted tumor, thus releasing the inhibitor from the Cy5.5 emitter. In this manner,
the Cy5.5 fluorescence will be inhibited everywhere but in the target. The dissociation was first examined in vitro by adding the duplex to the cMORF25 both in solution and immobilized on polystyrene microspheres and by surface plasmon resonance
(SPR). Thereafter, biotinylated cMORF25 immobilized on streptavidin polystyrene microspheres were administered intramuscularly
in one thigh of hairless SKH-1 mice as target while an identical weight of the identical microspheres but without the cMORF25
was administered in the contralateral thigh as control. The animals then received IV the Cy5.5–MORF25/BHQ3–cDNA18 duplex or
equal molar dosage of single-chain Cy5.5–MORF25 and were imaged.
Results The SPR studies showed that the immobilized cDNA18 rapidly captured the flowing MORF25 to provide a duplex with a slow dissociation
rate constant. Furthermore, when cMORF25 was next allowed to flow over the now immobilized duplex, the cDNA18 was unable to
prevent dissociation of the heteroduplex and the formation and release of the cMORF25-MORF25 homoduplex. Images of animals
obtained soon after receiving the Cy5.5–MORF25 singlet showed intense whole body fluorescence obscuring the target thigh.
However, only 5 minutes after receiving the Cy5.5–MORF25/BHQ3–cDNA18 duplex, the target thigh was clearly visible along with
only the kidneys.
Conclusions This first study of optical pretargeting provides a proof of concept that oligomer pretargeting found to be useful with radioactivity
detection is applicable with fluorescent detection as well. In addition, our results demonstrate that by using linear oligomers
for optical pretargeting, chain lengths (and base sequences) may be manipulated to provide duplexes with stabilities and fluorescence
inhibition optimized for pretargeting and other in vivo applications of optical imaging. 相似文献