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   2312篇
  免费   154篇
  国内免费   20篇
耳鼻咽喉   11篇
儿科学   87篇
妇产科学   62篇
基础医学   335篇
口腔科学   88篇
临床医学   171篇
内科学   518篇
皮肤病学   65篇
神经病学   155篇
特种医学   165篇
外科学   339篇
综合类   30篇
预防医学   154篇
眼科学   51篇
药学   150篇
中国医学   12篇
肿瘤学   93篇
  2022年   18篇
  2021年   48篇
  2020年   26篇
  2019年   40篇
  2018年   58篇
  2017年   26篇
  2016年   31篇
  2015年   57篇
  2014年   50篇
  2013年   72篇
  2012年   91篇
  2011年   99篇
  2010年   80篇
  2009年   83篇
  2008年   94篇
  2007年   124篇
  2006年   105篇
  2005年   91篇
  2004年   87篇
  2003年   78篇
  2002年   76篇
  2001年   71篇
  2000年   90篇
  1999年   71篇
  1998年   53篇
  1997年   60篇
  1996年   34篇
  1995年   36篇
  1994年   33篇
  1993年   16篇
  1992年   31篇
  1991年   42篇
  1990年   40篇
  1989年   43篇
  1988年   46篇
  1987年   47篇
  1986年   41篇
  1985年   33篇
  1984年   20篇
  1983年   21篇
  1982年   18篇
  1981年   17篇
  1980年   19篇
  1979年   16篇
  1978年   17篇
  1977年   12篇
  1976年   12篇
  1972年   12篇
  1971年   12篇
  1969年   11篇
排序方式: 共有2486条查询结果,搜索用时 15 毫秒
1.
The relationship of haemolytic disease of the newborn (HDN) to the transplacental passage of the four IgG subclasses was assessed at varous gestational ages by comparing the maternal and fetal IgG subclass concentrations in 34 pregnancies at risk of HDN with those in 30 pregnancies not at risk. Higher maternal and fetal IgG1 levels were attained in pregnancies at risk of HDN than in pregnancies not at risk. In contrast, a slight decrease in maternal IgG2 and IgG4 levels occurred in pregnancies at risk of HDN, as compared with a slight rise in maternal IgG2 and IgG4 levels in pregnancies not at risk of HDN. Changes in fetal IgG2 and 4 concentrations in either type of pregnancy were very similar, showing only slight increases between the 19th and 34th week of gestation. A slight decrease in maternal IgG3 occurred in both types of pregnancy. In contrast, higher and fairly steady levels of fetal IgG3 were observed in fetuses not at risk of HDN throughout gestation, when compared with those in 'at risk' pregnancies. However, the statistical reliability of these results is not clear since only small numbers of samples were tested and because wide variations in IgG concentrations were observed. The IgG subclass concentrations in 50 paired maternal and cord blood samples were also measured and revealed that IgG1 levels were substantially higher in cord rather than maternal blood; cord and maternal IgG2, 3 and 4 levels, on the other hand, were fairly similar.  相似文献   
2.
3.
We report the case of a 67-year-old man with a granular, cauliflower-pink lesion on the skin of the thigh. Histopathological study showed a typical verrucous carcinoma associated with a syringadenoma papilliferum. To our knowledge this association has not been previously reported.  相似文献   
4.
Glycine modulation of the phencyclidine binding site in mammalian brain   总被引:5,自引:0,他引:5  
Neurophysiological studies have shown that glycine potentiates the NMDA response in cultured neurons by a strychnine-insensitive mechanism. Autoradiographic data have demonstrated a correspondence between strychnine-insensitive [3H]glycine binding sites and NMDA-sensitive [3H]glutamate binding sites. Here we report that in synaptic plasma membranes from rat brain, the binding of a PCP analog, [3H]TCP, was enhanced more than 5-fold by 1 microM glycine. This glycine stimulation of binding of [3H]TCP was blocked by the competitive NMDA-receptor antagonist, D-AP7. These data provide support for the hypothesis that a unique amino acid recognition site is associated with the proposed NMDA/PCP receptor complex in brain.  相似文献   
5.
6.
The efficacy of the new nonsedating antihistamines loratadine and cetirizine was compared in a randomized, single-blind, crossover, controlled study with that of the classical antihistamines cyproheptadine and ketotifen in seven patients with primary acquired cold urticaria (ACU). The patients received each of the four drugs for 14 consecutive days with a 7-day interval between drugs. We evaluated clinical symptomatology, adverse effects, minimum time of cold contact stimulation required to induce an immediate coalescent wheal (CSTT), and inhibition of histamine-induced wheal response. Both loratadine and cetirizine showed suppression of symptoms with infrequent adverse effects. Important side-effects were observed in patients receiving cyproheptadine. Improvement in CSTT was statistically significant for all drugs compared with baseline values, without differences among them. The histamine-induced skin test was significantly inhibited by all antihistamines. Wheal reductions were 34.6% for loratadine and 50.9% for cetirizine. This study suggests that both loratadine and cetirizine may be effective in the treatment of primary ACU.  相似文献   
7.
8.
Abstrakt 1. Nimmt ein Patient einen ihm von seinem (Zahn-)Arzt einger?umten Exklusiv-Termin nicht wahr, obwohl er auf dessen Eigenschaft ausdrücklich hingewiesen wurde, so hat er dem (Zahn-)Arzt den Behandlungsausfall abzüglich eines angemessenen Eigenanteils des (Zahn-)Arztes zu ersetzen. 2. Die Ersatzpflicht tritt auch dann ein, wenn der Patient den Termin nicht in der in dem Behandlungsvertrag vorgesehenen Frist absagt. Eine hierfür seitens des (Zahn-)Arztes bestimmte Frist von zwei Tagen vor Behandlungsbeginn stellt sich für den Patienten grunds?tzlich auch nicht als unangemessene Benachteiligung i.S. des § 307 BGB dar. 3. Ein Anspruch des Arztes entf?llt auch bei nur mündlicher Vereinbarung nicht unter dem Gesichtspunkt des § 4 Abs. 5b BMV-Z, denn diese Vorschrift ist teleologisch dahin zu reduzieren, dass nur zahn?rztliche Honoraransprüche aus erfolgten Behandlungen schriftlich vereinbart werden müssen. Soweit es jedoch um einen vertraglichen Anspruch wegen einer Leistungsst?rung geht, vermag das Schriftformerfordernis des § 4 Abs. 5b BMV-Z grunds?tzlich nicht einzugreifen. (Leits?tze des Bearbeiters)  相似文献   
9.
Early during rat thymus ontogeny, an important proportion of thymocytes expresses IL-2R and contains IL-2 mRNA. To investigate the role of the IL-2-IL-2R complex in rat T cell maturation, we supplied either recombinant rat IL-2 or blocking anti-CD25 mAb to rat fetal thymus organ cultures (FTOC) under several experimental conditions. The IL-2 treatment initially stimulated the growth of thymocytes and, as a result, induced T cell differentiation, but the continuous addition of IL-2 to rat FTOC, as well as the anti-CD25 administration, resulted in cell number decrease and inhibition of thymocyte maturation. These results indicate that immature rat thymocytes bear functional high- affinity IL-2R and that IL-2 promotes T cell differentiation as a consequence of its capacity to stimulate cell proliferation. Modifications in TCR alpha beta repertoire and increased numbers of NKR- P1+ cells, largely NK cells, were also observed in IL-2-treated FTOC. Furthermore, IL-2-responsiveness of different thymocyte subsets changed throughout thymic ontogeny. Immature CD4-CD8-cells responded to IL-2 in two stages, early in thymus development and around birth, in correlation with the maturation of two distinct waves of thymic cell progenitors. Mature CD8+ thymocytes maximally responded to IL-2 around birth, supporting a role for IL-2 in the increased proliferation of mature thymocytes observed in vivo in the perinatal period. Taken together, these findings support a role for IL-2 in rat T cell development.   相似文献   
10.
A C1q solid phase microassay was designed for the rapid detection of circulating immune complexes. Its level of sensitivity is comparable to that of the Raji cell and greater than the C1q binding assay; furthermore, it is faster and low in cost. These conditions make it more practical and applicable in the clinical setting.  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