首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   150618篇
  免费   14028篇
  国内免费   8587篇
耳鼻咽喉   1156篇
儿科学   1897篇
妇产科学   1674篇
基础医学   22265篇
口腔科学   2827篇
临床医学   17693篇
内科学   21937篇
皮肤病学   1638篇
神经病学   7414篇
特种医学   5048篇
外国民族医学   65篇
外科学   14981篇
综合类   23468篇
现状与发展   29篇
一般理论   12篇
预防医学   10280篇
眼科学   3589篇
药学   17264篇
  122篇
中国医学   7872篇
肿瘤学   12002篇
  2024年   574篇
  2023年   2265篇
  2022年   5804篇
  2021年   7390篇
  2020年   5362篇
  2019年   4845篇
  2018年   5074篇
  2017年   4635篇
  2016年   4434篇
  2015年   6394篇
  2014年   7935篇
  2013年   7740篇
  2012年   10903篇
  2011年   11525篇
  2010年   8056篇
  2009年   6510篇
  2008年   7935篇
  2007年   7996篇
  2006年   7270篇
  2005年   6623篇
  2004年   5219篇
  2003年   5065篇
  2002年   4402篇
  2001年   3661篇
  2000年   3209篇
  1999年   2861篇
  1998年   1744篇
  1997年   1855篇
  1996年   1321篇
  1995年   1268篇
  1994年   1132篇
  1993年   811篇
  1992年   1171篇
  1991年   1053篇
  1990年   948篇
  1989年   914篇
  1988年   813篇
  1987年   717篇
  1986年   678篇
  1985年   569篇
  1984年   473篇
  1983年   396篇
  1982年   327篇
  1981年   272篇
  1980年   228篇
  1979年   274篇
  1978年   254篇
  1977年   266篇
  1976年   248篇
  1974年   213篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
42.
Human bladder cancer cell lines, J82, Yen-87, Shen-87 and Zoa-88, and murine bladder cancer cell lines, MBT-2 and M1660, were used as target cells for dye-sensitized photoinactivation study in using methylene blue. Normal fibroblast cells, FB-1 and FB8490, were used as control group. The cytoplasmic activity of lactic dehydrogenase, soft agar clonogenic assay, and in vivo tumor growth, survival rate and tumor taking rate with or without photoinactivation were monitored and compared between different cell lines. Efficacy of photoinactivation was time-related and more than 90 per cent of cytotoxicity could be obtained within 60 minutes of illumination. The plateau of cytotoxicity curve could be achieved after staining for 30 minutes by methylene blue under the same illumination time. Normal fibroblasts had the same features with cancer cells. Photoinactivation of tumor cells showed significant inhibition of tumor growth and tumor taking rate in experimental animals. Survival rate was also significantly prolonged in the animals with tumor cells receiving photoinactivation. These results suggest that methylene blue-sensitized photoinactivation may be useful as an adjuvant photochemotherapy for superficial bladder cancer.  相似文献   
43.
44.
1. Endothelium-dependent relaxation in response to acetylcholine (ACh) and the calcium ionophore A 23187 was examined in aorta, coronary, basilar and renal arteries isolated from Watanabe heritable hyperlipidaemic (WHHL) rabbits of 2, 6 and 12 months of age, with normolipidaemic heterozygous WHHL rabbits as controls. 2. In the rings of WHHL rabbit aortae and coronary arteries preconstricted with vasoconstrictors, endothelium-dependent relaxation in response to ACh was attenuated with age compared to the heterozygous WHHL rabbits. A significant negative correlation was found between the total cholesterol content and the relaxation response to ACh in the aortae or coronary arteries from 6 and 12 month old WHHL rabbits. 3. In the rings of basilar arteries, endothelium-dependent relaxations to ACh were not modified with age. Similarly, in the rings of renal arteries, the relaxation response to ACh was not changed with age, but in the 6 and 12 month preparations, after the age of 6 months, a contraction following the relaxation appeared at higher concentrations of ACh (10?7 to 10?6 mol/L). The contraction was endothelium-dependent and inhibited by indomethacin. 4. A 23187-induced endothelium-dependent relaxations were also markedly attenuated in the aorta and significantly in the coronary artery with age. 5. Endothelium-independent relaxation to sodium nitroprusside was not changed in all arteries from WHHL rabbits of different ages. 6. These findings indicate that in the aorta and coronary artery of the WHHL rabbit, the endothelium-dependent relaxation to ACh and A 23187 becomes impaired with increasing age (i.e., with the progression of cholesterol deposition in the arterial wall) but is preserved in the basilar and renal artery.  相似文献   
45.
46.
47.
Translated from Khimiko-farmatsevticheskii Zhurnal, Vol. 26, No. 1, pp. 44–45, January, 1992.  相似文献   
48.
Because of the lack of adequate strength and toughness, hydroxyapatite (HA) ceramic can not be used for a substitute for a bone and joint despite its excellent affinity for the bone. The present authors have succeeded in producing a new type of HA ceramic containing zirconia. This new ceramic material is superior to ordinary HA ceramic in quality and exceeds compact bone in bending strength and fracture toughness. The Young's modulus was about 3-4 times greater than that of compact bone. The new ceramic material contained either 1.6 or 50% of zirconia by volume and was produced using a special technique to disperse the metal dioxide. In order to assess their affinity for the bone, the new ceramic materials were implanted into rabbit femurs. Sections of the bones removed at different times after operation were prepared without decalcification and subjected to optical microscopy, scanning electronmicroscopy (SEM), and electron-probe X-ray microanalyser (EPMA). The formation of direct chemical bonds with the bone was seen without intervening membrane. Thus, the new ceramic material was shown to have an excellent affinity for the bone, comparable to that of ordinary HA ceramic.  相似文献   
49.
The visual pursuit test is a method that collects and analyzes the characteristics of pursuit eye movements and examines the function of the eye movement system. This paper analyzes the model parameters of the smooth pursuit eye movement system in order to explore a method for improving the analysis. The input-output relationship of the smooth pursuit system can be expressed by a quasilinear model. We compute the model parameters (gain, phase, spectral purity, cross covariance) by digital signal processing. Eye movement is recorded by electrooculogram. Both eyes are tested individually. The visual target moves at frequencies of 0.2, 0.4, 0.8, 1.2, and 1.6 Hz. Ranges are gain, 1.01 to 0.70; phase, -0.1 ° to -66 °; spectral purity, 0.97 to 0.70; and cross covariance, 0.99 to 0.26. We tested 40 normal subjects as well as patients with ataxia (8), vertigo (18), and ophthalmoplegia (9). The oculomotor system of normal subjects functions as a linear system in the performance of this test at 0.2 to 0.8 Hz. The spectral purity dropped to about 0.70 at 1.6 Hz. The variability of all measures increases greatly at 1.6 Hz, which indicates that this target motion exceeds the tracking ability of many normal subjects and that the oculomotor system of normal subjects functions as a nonlinear system in this condition. Statistical tests show no significant differences between sex, age, and the two eyes. The model parameters tentatively proved effective in clinical application.  相似文献   
50.
目的评价经皮椎体成形术治疗脊柱疾病的临床应用价值.方法 56例多发骨髓瘤、溶骨性脊柱转移瘤、骨质疏松性椎体压缩性骨折患者应用经皮椎体成形术后,分24 h、3个月两阶段评估患者疼痛、术后X线片检查结果、椎体高度等指标.结果术后止痛效果良好,尤以骨质疏松性椎体压缩性骨折患者的止痛效果最好.无严重并发症. 结论经皮椎体成形术对骨质疏松性椎体压缩性骨折等脊柱疾病的止痛、稳固椎体等效果明显,可以谨慎开展.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号