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   5477篇
  免费   253篇
  国内免费   65篇
耳鼻咽喉   24篇
儿科学   60篇
妇产科学   39篇
基础医学   676篇
口腔科学   52篇
临床医学   309篇
内科学   1463篇
皮肤病学   41篇
神经病学   413篇
特种医学   359篇
外科学   1012篇
综合类   49篇
预防医学   217篇
眼科学   50篇
药学   344篇
中国医学   8篇
肿瘤学   679篇
  2023年   41篇
  2022年   75篇
  2021年   108篇
  2020年   60篇
  2019年   92篇
  2018年   105篇
  2017年   105篇
  2016年   117篇
  2015年   117篇
  2014年   167篇
  2013年   169篇
  2012年   322篇
  2011年   340篇
  2010年   212篇
  2009年   177篇
  2008年   329篇
  2007年   352篇
  2006年   352篇
  2005年   348篇
  2004年   324篇
  2003年   329篇
  2002年   350篇
  2001年   103篇
  2000年   84篇
  1999年   92篇
  1998年   69篇
  1997年   63篇
  1996年   60篇
  1995年   63篇
  1994年   54篇
  1993年   67篇
  1992年   54篇
  1991年   63篇
  1990年   33篇
  1989年   41篇
  1988年   34篇
  1987年   28篇
  1986年   22篇
  1985年   33篇
  1984年   43篇
  1983年   27篇
  1982年   17篇
  1981年   27篇
  1980年   13篇
  1979年   15篇
  1977年   14篇
  1976年   9篇
  1975年   8篇
  1974年   8篇
  1969年   10篇
排序方式: 共有5795条查询结果,搜索用时 15 毫秒
41.
Purpose

Intravesical bacillus Calmette–Guérin (BCG) is the standard of care for bladder carcinoma in situ (CIS). The response to BCG therapy against CIS is generally assessed by random bladder biopsy (RBB). In this study, we examined the necessity of routine RBB after BCG therapy.

Methods

We retrospectively identified 102 patients who were initially diagnosed with CIS with or without papillary tumor and received subsequent 6–8-week BCG therapy. Thereafter, all patients underwent voiding cytology analysis, cystoscopy, and RBB to evaluate the effects of BCG therapy. We evaluated the association between clinical parameters (voiding cytology and cystoscopy findings) and the final pathological results by RBB specimens.

Results

According to the pathological results of RBB, 30 (29%) patients had BCG-unresponsive disease (remaining urothelial carcinoma was confirmed pathologically) and 20 were diagnosed with CIS. Positive/suspicious voiding cytology and positive cystoscopy findings were well observed in patients who had BCG-unresponsive disease compared with their counterparts (p?=?0.116, and p?<?0.001, respectively). The sensitivity (Sen.), specificity (Spe.), positive predictive value (PPV), and negative predictive value (NPV) of voiding cytology were 50%, 68%, 39%, and 77%, respectively. The values for cystoscopy findings were as follows: Sen.: 87%, Spe.: 57%, PPV: 46%, and NPV: 91%. The values for their combination (having either of them) were as follows: Sen.: 100%, Spe.: 44%, PPV: 43%, and NPV: 100%.

Conclusion

RBB after BCG therapy for patients with negative voiding cytology and negative cystoscopy may be omitted because their risk of BCG-unresponsive disease is significantly low (NPV: 100%).

  相似文献   
42.
43.
44.
45.
Key words  dysrhythmia - isorhythmic dissociation - oscillation  相似文献   
46.
Great horovement haS been made in the cryopreservation Of inalnlnalian elnbmp since wnttingham['] reported his Pioneering wold about successful cryOPreservationof mouse embryo. It results in the availability of cryOPreserVation of embryos of all stages[']. HOwever, cryopreserved embryos can not avoid the damages by ice crystal,which is a major cause of cen death in the freezing andthawing ProceduresL',']. SO it is necesseq to seareh for anew and more efficient method for embryO cryOPrese…  相似文献   
47.
  1. Desensitization of μ- and κ-opioid receptor-mediated inhibition of voltage-dependent Ca2+ channels was studied in a Xenopus oocyte translation system.
  2. In the oocytes coexpressing κ-opioid receptors with N- or Q-type Ca2+ channel α1 and β subunits, the κ-agonist, U50488H, inhibited both neuronal Ca2+ channel current responses in a pertussis toxin-sensitive manner and the inhibition was reduced by prolonged agonist exposure.
  3. More than 10 min was required to halve the inhibition of Q-type channels by the κ-agonist. However, the half-life for the inhibition of N-type channels was only 6±1 min. In addition, in the oocytes coexpressing μ-opioid receptors with N-type or Q-type channels, the uncoupling rate of the μ-receptor-mediated inhibition of N-channels was also faster than that of Q-type channels.
  4. In the oocytes coexpressing both μ- and κ-receptors with N-type channels, stimulation of either receptor resulted in a cross-desensitization of the subsequent response to the other agonist. Treatment of oocytes with either H-8 (100 μM), staurosporine (400 nM), okadaic acid (200 nM), phorbol myristate acetate (5 nM) or forskolin (50 μM) plus phosphodiesterase inhibitor did not affect either the desensitization or the agonist-evoked inhibition of Ca2+ channels.
  5. These results suggest that the rate of rapid desensitization is dependent on the α1 subtype of the neuronal Ca2+ channel, and that a common phosphorylation-independent mechanism underlies the heterologous desensitization between opioid receptor subtypes.
  相似文献   
48.
Summary We found that a receptor ligands differentially regulated the acetylcholine (ACh) neurotransmission in the rat brain. Acute administration of (+)-N-allylnormetazocine [(+)-SKF-10,047], a prototype 1 receptor ligand, and 1,3-di(2-tolyl)guanidine (DTG), a non-specific receptor ligand, increased the extracellular ACh level in the rat hippocampus. This increase of hippocampal extracellular ACh level elicited by (+)-SKF-10,047 was more potent than that elicited by DTG. On the other hand, the striatal extracellular ACh level was slightly affected by (+)-SKF-10,047. In addition, DTG did not affect the striatal extracellular ACh level. Our previous studies have shown that both (+)-SKF-10,047 and DTG increased the extracellular ACh level in the rat frontal cortex. Taking all these data into consideration, the regulation of ACh neurotransmission by receptor ligands are different depending upon the brain region.  相似文献   
49.
Attenuation coefficient maps (-maps) are a useful way to compensate for non-uniform attenuation when performing single photon emission tomography (SPET). A new method was developed to record single photon transmission data and a-map for the brain was produced using a four-head SPET scanner. Transmission data were acquired by a gamma camera opposite to a flood radioactive source attached to one of four gamma cameras in the four-head SPET scanner. Attenuation correction was performed using the iterative expectation maximization algorithm and the-map. Phantom studies demonstrated that this method could reconstruct the distribution of radioactivity more accurately than conventional methods, even for a severely non-uniform-map, and could improve the quality of SPET images. Clinical application to technetium-99m hexamethylpropylene amine oxime (HMPAO) brain SPET also demonstrated the usefulness of this method. Thus, this method appears to be promising for improvement in the image quality and quantitative accuracy of brain SPET.This work was presented in part at the World Congress on Medical Physics and Biomedical Engineering, 7–12 July 1991, Kyoto, Japan  相似文献   
50.
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