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   7816篇
  免费   893篇
  国内免费   65篇
耳鼻咽喉   103篇
儿科学   182篇
妇产科学   253篇
基础医学   943篇
口腔科学   138篇
临床医学   835篇
内科学   1819篇
皮肤病学   107篇
神经病学   540篇
特种医学   307篇
外国民族医学   1篇
外科学   1304篇
综合类   268篇
一般理论   3篇
预防医学   483篇
眼科学   153篇
药学   603篇
中国医学   66篇
肿瘤学   666篇
  2023年   60篇
  2022年   138篇
  2021年   268篇
  2020年   183篇
  2019年   249篇
  2018年   273篇
  2017年   219篇
  2016年   235篇
  2015年   294篇
  2014年   344篇
  2013年   386篇
  2012年   515篇
  2011年   522篇
  2010年   378篇
  2009年   228篇
  2008年   389篇
  2007年   415篇
  2006年   394篇
  2005年   362篇
  2004年   323篇
  2003年   273篇
  2002年   250篇
  2001年   156篇
  2000年   164篇
  1999年   162篇
  1998年   70篇
  1997年   73篇
  1996年   48篇
  1995年   50篇
  1994年   41篇
  1993年   31篇
  1992年   109篇
  1991年   110篇
  1990年   121篇
  1989年   102篇
  1988年   117篇
  1987年   87篇
  1986年   87篇
  1985年   71篇
  1984年   49篇
  1983年   47篇
  1982年   28篇
  1981年   24篇
  1980年   23篇
  1979年   27篇
  1978年   22篇
  1974年   22篇
  1973年   22篇
  1971年   21篇
  1970年   24篇
排序方式: 共有8774条查询结果,搜索用时 0 毫秒
51.
52.
53.
Several fixation and permeabilization techniques that enable the flow cytometric analysis of the cell contents have been introduced in recent years. These methods allow sensitive detection of intracellular antigens that facilitates the diagnosis of certain diseases. We have undertaken in this study to evaluate a simple method of fixation and permeabilization using 2% paraformaldehyde and Tween 20. Intracellular antigens in three different leukaemia cases were analysed. We found that the method was reliable and easy. Intracellular kappa light chains were found in abundance in a case of plasma cell leukaemia. CD3 and CD22 were found in greater amount intracellularly than on the surface in pre-T-ALL and pre-pre B-ALL respectively.  相似文献   
54.
55.
The safety and efficacy of controlled-delivery (CD) once-a-day formulation of diltiazem administered in the evening, at a dose of 240 mg, was assessed in 37 patients with stable angina pectoris. A double-blind, placebo-controlled, randomized, crossover protocol was used. Following a 4-day washout period, patients entered a 5--7-day single-blind placebo run-in period during which qualification and reproducibility exercise treadmill tests (ETTs) were performed 24 h postdose. Eligible patients were randomized in a double-blind fashion, to either CD diltiazem or to placebo for a 7--10-day treatment period. They then entered a 5--7-day single-blind washout period, after which they received the alternate treatment for another 7 to 10 days. ETTs were performed at the end of each treatment period. Compared to placebo, evening administration of CD diltiazem produced a marked improvement of the time to ETT termination, time to onset of angina, and time to 1 mm ST depression. In addition, the number of angina attacks recorded in patient diaries was reduced compared to placebo. Incidence of adverse events was comparable with CD diltiazem and placebo. We conclude that evening administration of controlled-delivery diltiazem is highly effective and safe in the treatment of stable angina pectoris.  相似文献   
56.
57.
58.
Expression of calcium channel alpha1 subunits in oocytes or cell lines has proven to be a powerful method in the analysis of structure-function relations, but these experimental systems are of limited value in the examination of neuron-specific functions such as transmitter release. Cell lines derived from neurons are often capable of these functions, but their intrinsic calcium channel alpha1 subunits are complicating factors in experimental design. We have examined the biophysical and molecular properties of calcium channels in a little studied neuroblastoma-glioma hybrid cell line, 140-3, a close relative of the NG108-15 cell line, to test whether this cell line might serve a role as an expression system for neural mechanisms. This cell was selected as it contains an intact transmitter release mechanism yet secretes little in response to depolarization. Patch-clamp recording revealed only a prominent low-threshold, rapidly inactivating calcium current with a single-channel conductance of approximately 7 pS that was identified as T type. A search for calcium channel alpha1 subunit messenger RNA in the 140-3 cells with three different tests only revealed alpha1C, whereas alpha1A-alpha1C were present in the parent NG108-15 line. We made a particular effort to search for alpha1E, since this subunit has been associated with a low-voltage-activated current. Our findings suggest that, since the principal nerve terminal-associated calcium channels (alpha1A, alpha1B, alpha1E) are absent in the 140-3 cell, this cell line may prove a particularly useful model for the analysis of the role of high-voltage-activated calcium channels in complex functions of neuronal cells.  相似文献   
59.
目的观察吡哌酸锌软膏促进烧伤愈合的作用。方法用230℃的圆铁板造成大鼠背部烧伤,以不同浓度的吡哌酸锌及磺胺嘧啶银霜、磺胺嘧啶锌软膏、吡哌酸软膏、软膏基质每日涂药一次,连续15d。d16测量未愈合烧伤创面面积。结果吡哌酸锌软膏及磺胺嘧啶锌软膏均能明显促进创面愈合,两者之间无显著差异(P>0.05),但磺胺嘧啶银霜、吡哌酸软膏等促进创面愈合作用不明显(P>0.05)。结论吡哌酸锌软膏能明显促进烧伤创面的愈合。  相似文献   
60.
PURPOSE: Studies were conducted to examine the effect of hydrogen peroxide on active sodium-potassium transport in a cell line derived from nonpigmented ciliary epithelium of the rabbit eye. METHODS: Studies were carried out using a rabbit nonpigmented ciliary epithelium cell line. 86Rb uptake by intact cells was measured in the presence or absence of ouabain. The ouabain-sensitive potassium (86Rb) uptake rate was used as an index of the rate of active sodium-potassium transport. Cell sodium content was measured by atomic absorption spectrophotometry. Na,K-ATPase activity was determined by measuring ATP hydrolysis in the presence or absence of ouabain, using membrane material isolated by centrifugation of cell homogenates. RESULTS: Ouabain-sensitive potassium (86Rb) uptake rate measured in cells that had been preincubated with 200microM hydrogen peroxide for either 30 min or 60 min was increased to 196% and 181% of the control uptake rate, respectively. Lesser concentrations of hydrogen peroxide caused lesser degrees of stimulation. 200microM hydrogen peroxide caused an increase of cell sodium content. Such a change of cell sodium content is likely to be responsible, at least in part, for the observed stimulation of active sodium-potassium transport. However, the response may also be partly dependent on activation of a protein kinase since the serine/threonine protein kinase inhibitors staurosporine (1microM) and H-89 (20microM) were both found to prevent the stimulatory effect of 200microM hydrogen peroxide on ouabain-sensitive potassium (86Rb) uptake. Interestingly, neither H-89 nor staurosporine prevented the elevation of sodium content in cells that received 200microM hydrogen peroxide. CONCLUSIONS: Taken together, these findings suggest a low concentration of hydrogen peroxide causes increased sodium entry into the cell and also activates a protein kinase-dependent mechanism for sodium pump stimulation. The protein kinase-dependent mechanism does not appear to be triggered by an increased rate of sodium entry since staurosporine did not prevent the stimulation of ouabain-sensitive potassium (86Rb) uptake elicited by an increase in sodium permeability caused by amphotericin B.  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