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   13800篇
  免费   817篇
  国内免费   43篇
耳鼻咽喉   137篇
儿科学   822篇
妇产科学   352篇
基础医学   1550篇
口腔科学   239篇
临床医学   1083篇
内科学   2590篇
皮肤病学   359篇
神经病学   1091篇
特种医学   364篇
外国民族医学   1篇
外科学   1859篇
综合类   301篇
一般理论   22篇
预防医学   930篇
眼科学   538篇
药学   1326篇
中国医学   55篇
肿瘤学   1041篇
  2023年   112篇
  2022年   231篇
  2021年   471篇
  2020年   273篇
  2019年   370篇
  2018年   424篇
  2017年   342篇
  2016年   376篇
  2015年   386篇
  2014年   492篇
  2013年   739篇
  2012年   987篇
  2011年   1071篇
  2010年   584篇
  2009年   441篇
  2008年   766篇
  2007年   787篇
  2006年   675篇
  2005年   625篇
  2004年   578篇
  2003年   485篇
  2002年   454篇
  2001年   304篇
  2000年   304篇
  1999年   262篇
  1998年   118篇
  1997年   84篇
  1996年   96篇
  1995年   76篇
  1994年   54篇
  1993年   50篇
  1992年   119篇
  1991年   161篇
  1990年   133篇
  1989年   107篇
  1988年   110篇
  1987年   77篇
  1986年   85篇
  1985年   90篇
  1984年   66篇
  1983年   68篇
  1979年   66篇
  1978年   44篇
  1977年   36篇
  1975年   34篇
  1973年   38篇
  1972年   41篇
  1971年   44篇
  1969年   32篇
  1968年   44篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
22.
Tetrabenazine (TBZ), a presynaptic dopamine depletor and postsynaptic dopamine receptor blocker, is widely used for the treatment of hyperkinetic movement disorders in adults. However, reports of its use in children are limited. We review the efficacy and tolerability of TBZ therapy in 31 children with hyperkinetic movement disorders refractory to other medications. TBZ was effective in reducing the severity of movement disorders resistant to treatment with other medicines. When compared to adult patients, pediatric patients required higher doses. Side effects were similar to the adult population; however, children had a lower incidence of drug-induced Parkinsonism.  相似文献   
23.
24.
25.
26.
To identify the role of protein kinase C (PKC) isoforms in multidrug resistance in tumor cells, we examined the PKC isoform pattern in the multidrug resistant P388/ADR cell line and studied the effect of down regulation of PKC isoforms on intracellular daunorubicin accumulation and P-glycoprotein expression. Using monoclonal antibodies to PKC alpha, beta and gamma and flow cytometry technique we showed that P388/ADR cells overexpressed PKC alpha and beta as compared to drug sensitive P388 cells. Prolonged treatment of P388/ADR cells with phorbol myristate acetate (PMA), a procedure that is known to down regulate PKC, resulted in the down regulation of total PKC activity and the PKC beta isoform (at the protein level) that was accompanied by the correction of daunorubicin accumulation in P388/ADR cells. The level of expression of P-glycoprotein in PMA treated cells was similar to that of untreated cells. These results suggest that PKC beta regulates the drug efflux function of P-glycoprotein.  相似文献   
27.
Fertility reduction and the quality of family planning services   总被引:5,自引:0,他引:5  
The purpose of this paper is to determine whether a focus on quality of family planning services is consistent with meeting demographic objectives. An analytical framework that links the six elements of quality with fertility is described. A review of existing literature and analysis suggest that improvements in quality of family planning services by enhancing the choice of contraceptive methods available in a country would increase the overall practice of contraception and thus would result in fertility reduction.  相似文献   
28.
This study investigated relationships between child/parent dissatisfaction with child facial appearance and the self-concept/social competence of 8- to 15-year-old children with (N = 34) and without (N = 34) oral clefts. Children in both groups had normative psychosocial adjustment, but also reported moderate dissatisfaction with facial appearance. Cleft group parents were more likely to agree with their child's dissatisfaction. When cleft group parents were more dissatisfied with child facial appearance, their children reported better quality of life. Results suggest that parents of children with clefts reporting greater dissatisfaction may respond in positive ways that enhance quality of life.  相似文献   
29.
Effect of titanium surface texture on the cell-biomaterial interface.   总被引:1,自引:0,他引:1  
To improve the in vivo performance of engineered implants, this study examines the independent effects of surface chemistry and topography on fibroblast morphology and density in vitro. Titanium (Ti) was sputter-coated onto smooth and microtextured polyethylene terephthalate (PET). Test specimens were evaluated in 24-h, fibroblast cultures and assessed with scanning electron microscopy (SEM) for cellular morphology and density. Fibroblast density increased, as the Ti film thickness increased. The fibroblasts exhibited contact guidance on the textured test specimens. The greatest cellular density was found on the Ti-coated, textured test specimens. In conclusion, Ti and surface texture appeared to strongly influence fibroblast density and morphology as compared to PET and smooth surfaces.  相似文献   
30.
Objective : To measure the geometric resistance to blood flow in human colorectal carcinoma. Although tumor blood flow is of central importance in both the detection and the treatment of cancer, the determinants of blood flow through the neoplastic circulation are poorly understood. Methods : Human colorectal carcinomas (tissue weight = 272 g ± 43 g (SD), n = 6) were perfused ex vivo with a buffered physiological salt solution of known viscosity at flow rates ranging from 2.5 to 40 ml/min and perfusion pressures from 8 to 100 mm Hg. The geometric resistance was determined from the slope of the pressure-flow curve. For examination of the principal determinant of geometric resistance, the vascular architecture, one of the tumors was perfused with Batson's No. 17 polymer and macerated in KOH to produce a positive vascular cast that was used for measurement of vascular branching patterns and dimensions. Results : The pressure-flow relationship was linear at perfusion pressures above 40 mm Hg, and the geometric resistance, z0, was constant at approximately 6.5 ± 109g/cm3. Below 40 mm Hg, z0 increased rapidly. The architecture of the arteriolar and capillary networks of human colorectal carcinoma is similar to those of experimental rodent tumors. Capillaries in planar and nonplanar mesh-works had mean segment diameters of 11 ± 2 and 9.6 ± 2 μm, lengths of 46 ± 24 and 107 ± 40 μm, and intercapillary distances of 46 ± 13 and 74 ± 24 μm, respectively. Conclusions : The geometric flow resistance in neoplastic tissue is 1–2 orders of magnitude higher than that observed in normal tissues. A decrease in functional vascular cross-sectional area may explain the additional increase in resistance at small perfusion pressures. The observed flow resistance may be due to the specialized arteriolar and capillary network architecture, pressures exerted by proliferating cancer cells, and/or coupling between vascular and extravascular flow. These observations demonstrate that tumor vascularity alone may not be indicative of flow resistance or tumor susceptibility to blood-borne therapeutic agents.  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