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   1499篇
  免费   107篇
  国内免费   2篇
耳鼻咽喉   15篇
儿科学   17篇
妇产科学   24篇
基础医学   247篇
口腔科学   26篇
临床医学   152篇
内科学   253篇
皮肤病学   7篇
神经病学   330篇
特种医学   67篇
外科学   187篇
综合类   3篇
预防医学   69篇
眼科学   37篇
药学   102篇
中国医学   1篇
肿瘤学   71篇
  2023年   13篇
  2022年   23篇
  2021年   50篇
  2020年   39篇
  2019年   38篇
  2018年   43篇
  2017年   41篇
  2016年   40篇
  2015年   46篇
  2014年   55篇
  2013年   76篇
  2012年   112篇
  2011年   100篇
  2010年   70篇
  2009年   68篇
  2008年   89篇
  2007年   79篇
  2006年   105篇
  2005年   84篇
  2004年   72篇
  2003年   67篇
  2002年   66篇
  2001年   20篇
  2000年   12篇
  1999年   18篇
  1998年   13篇
  1997年   13篇
  1996年   6篇
  1995年   8篇
  1994年   5篇
  1993年   5篇
  1992年   17篇
  1991年   5篇
  1990年   13篇
  1989年   15篇
  1988年   12篇
  1987年   13篇
  1986年   8篇
  1985年   6篇
  1982年   3篇
  1978年   3篇
  1977年   3篇
  1976年   7篇
  1975年   3篇
  1974年   5篇
  1970年   2篇
  1969年   2篇
  1930年   2篇
  1908年   2篇
  1893年   1篇
排序方式: 共有1608条查询结果,搜索用时 0 毫秒
11.
BackgroundThe therapeutic armamentarium for patients with metastatic breast cancer is becoming more and more specific. Recommendations from clinical trials are not available for all treatment situations and patient subgroups, and it is therefore important to collect real-world data.SummaryTo develop recommendations for up-to-date treatments and participation in clinical trials for patients with metastatic breast cancer, the Prospective Academic Translational Research PRAEGNANT Network was established to optimize the quality of oncological care in the advanced therapeutic setting. The main aim of PRAEGNANT is to systematically record medical care for patients with metastatic breast cancer in the real-life setting, including the outcome and side effects of different treatment strategies, to monitor quality-of-life changes during therapy, to identify patients eligible for participation in clinical studies, and to allow targeted therapies based on the molecular structures of breast carcinomas.Key MessagesThis article describes the PRAEGNANT network and sheds light on the question of whether the various end points from clinical trials can be transferred to the real-world treatment situation.  相似文献   
12.
13.
The survival of grafted embryonic striatal tissue, dissected from the lateral ganglionic eminence, depends on the status of the host striatum. We found significantly larger volumes of surviving graft tissue and of striatal-like tissue (P-zone) within the graft, when the host striatum had been subjected to an excitotoxic lesion prior to transplantation surgery. Concomitantly the numbers of surviving grafted cells, assessed in both cresyl violet-stained sections and in sections stained with an immunohistochemical marker for striatal neurons, increased as compared to when graft tissue was placed in an intact unlesioned striatum. Finally, we examined the impact of treatment of the donor tissue with ciliary neurotrophic factor (CNTF) on graft survival. CNTF has previously been shown to protect striatal neurons against excitotoxic insults both in vitro and in vivo, but it did not improve striatal graft survival when added to the cell suspension prior to implantation.  相似文献   
14.
Ciliary neurotrophic factor (CNTF) has a protective effect on the striatum in animal models of Huntington's disease. However, the mechanism through which it exerts its effect is not clear. In this study, we show that there is a concentration-dependent direct protective effect of CNTF against N-methyl-D-aspartate-mediated excitotoxicity on striatal neurons in vitro. The CNTF has to be added more than half an hour before the insult for the effect to occur and its effect is eliminated by the presence of the protein synthesis inhibitor cycloheximide. This suggests that the protective mechanism of CNTF does not involve acute interference with the glutamate receptors, but probably requires gene/protein expression. We have also shown that the effect of CNTF against glutamate-induced excitotoxicity is dependent on the concentration of glutamate with a protective effect more evident at a low grade excitotoxic insult. Finally, we saw no effect of CNTF on calcium ionophore A23187-induced toxicity in striatal cultures, indicating that the growth factor does not promote survival by enhancing general defenses against raised intracellular levels of calcium.  相似文献   
15.
Northern blot analysis was used to demonstrate high levels of hippocampus-derived neurotrophic factor/neurotrophin-3 (HDNF/NT-3) mRNA in the embryonic day (E) 13 - 14 and 15 - 16 spinal cord. The level decreased at E18 - 19 and remained the same until postnatal day (P) 1, after which it decreased further to a level below the detection limit in the adult. In situ hybridization revealed that the NT-3 mRNA detected in the developing spinal cord was derived from motoneurons and the decrease seen at E18 - 19 was caused by a reduction in the number of motoneurons expressing NT-3 mRNA. The distribution of NT-3 mRNA-expressing cells in the E15 spinal cord was very similar to the distribution of cells expressing choline acetyltransferase or nerve growth factor receptor (NGFR) mRNA. Moreover, a striking similarity between the developmentally regulated expression of NT-3 and NGFR mRNA was noted in spinal cord motoneurons. A subpopulation of all neurons in the dorsal root ganglia expressed brain-derived neurotrophic factor (BDNF) mRNA from E13, the earliest time examined, to adulthood. These results are consistent with a trophic role of NT-3 for proprioceptive sensory neurons innervating the ventral horn, and imply a local action of BDNF for developing sensory neurons within the dorsal root ganglia.  相似文献   
16.
For the first time the human intestinal effective permeability, estimated from the luminal disappearance and intestinal metabolism of phytochemicals, sulforaphane and quercetin-3,4'-glucoside, as well as the simultaneous changes in gene expression in vivo in enterocytes, has been studied in the human jejunum in vivo (Loc-I-Gut). Both compounds as components of an onion and broccoli extract could readily permeate the enterocytes in the perfused jejunal segment. At the physiologically relevant, dietary concentration tested, the average effective jejunal permeability (Peff) and percentage absorbed (+/- S.D.) were 18.7 +/- 12.6 x 10-4 cm/s and 74 +/- 29% for sulforaphane and 8.9 +/- 7.1 x 10-4 cm/s and 60 +/- 31% for quercetin-3,4'-diglucoside, respectively. Furthermore, a proportion of each compound was conjugated and excreted back into the lumen as sulforaphane-glutathione and quercetin-3'-glucuronide. The capacity of the isolated segment to deconjugate quercetin from quercetin-3,4'-diglucoside during the perfusion was much higher than the beta-glucosidase activity of the preperfusion jejunal contents, indicating that the majority (79-100%) of the beta-glucosidase capacity derives from the enterocytes in situ. Simultaneously, we determined short-term changes in gene expression in exfoliated enterocytes, which showed 2.0 +/- 0.4-fold induction of glutathione transferase A1 (GSTA1) mRNA (p < 0.002) and 2.4 +/- 1.2-fold induction of UDP-glucuronosyl transferase 1A1 (UGT1A1) mRNA (p < 0.02). The changes in gene expression were also seen in differentiated Caco-2 cells, where sulforaphane was responsible for induction of GSTA1 and quercetin for induction of UGT1A1. These results show that food components have the potential to modify drug metabolism in the human enterocyte in vivo very rapidly.  相似文献   
17.
A hydrogelic intratubal device, called P-block, Mark 9, was inserted hysteroscopically with local anesthesia in the intramural part of the fallopian tube of 25 women referred for the procedure as an alternative to abdominal sterilization. Hysterosalpingography revealing bilateral oviductal patency was followed by hysteroscopic checkup verifying bilateral presence of P-blocks, except in three patients who had expulsion of the P-blocks on one side. All of the 22 patients had retention of the P-blocks 6 to 7 months after insertion. None became pregnant. Thus it is suggested that an intratubal device in the isthmic part of the human fallopian tube acts as an intrauterine contraceptive device, preventing intratubal and intrauterine pregnancies. Endeavors to explain the contraceptive effect of a nonocclusive intratubal device are discussed on the basis of our present knowledge of tubal physiology. Distension of part of the human isthmus is likely to disturb normal gamete transport through the isthmus.  相似文献   
18.
Pituitary tumor apoplexy (PTA) classically comprises sudden-onset headache, loss of vision, ophthalmoparesis, and decreased consciousness. It typically results from hemorrhage and/or infarction within a pituitary adenoma. Presentation is heterologous, and optimal management is debated. The time course of recovery of cranial nerve deficits (CNDs) and headaches is not well established. In this study, a retrospective series of consecutive patients with PTA managed at a single academic institution over a 22-year period is presented. Headaches at the time of surgery were more severe in the early and subacute surgical cohort and improved significantly within 72 h postoperatively (p < 0.01). At one year, 90% of CNDs affecting cranial nerves (CNs) 3, 4, and 6 had recovered, with no differences between early (<4 d), subacute (4–14 d), and delayed (>14 d) time-to-surgery cohorts. Remarkably, half recovered within three days. In total, 56% of CN2 deficits recovered, with the early surgery cohort including more severe deficits and recovering at a lower rate (p = 0.01). No correlation of time-to-surgery and rapidity of recovery of CNDs was observed (p = 0.65, 0.72). Surgery for PTA is associated with rapid recovery of CNDs in the early, subacute, and delayed time frames, and with rapid headache improvement in the early and subacute time frames in 50% or more of patients.  相似文献   
19.
20.
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