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   2087篇
  免费   96篇
  国内免费   3篇
耳鼻咽喉   28篇
儿科学   121篇
妇产科学   25篇
基础医学   238篇
口腔科学   89篇
临床医学   121篇
内科学   291篇
皮肤病学   17篇
神经病学   111篇
特种医学   61篇
外科学   285篇
综合类   60篇
一般理论   2篇
预防医学   103篇
眼科学   100篇
药学   318篇
中国医学   23篇
肿瘤学   193篇
  2023年   12篇
  2022年   37篇
  2021年   63篇
  2020年   52篇
  2019年   30篇
  2018年   47篇
  2017年   41篇
  2016年   47篇
  2015年   47篇
  2014年   87篇
  2013年   87篇
  2012年   160篇
  2011年   184篇
  2010年   77篇
  2009年   69篇
  2008年   90篇
  2007年   112篇
  2006年   119篇
  2005年   92篇
  2004年   110篇
  2003年   101篇
  2002年   76篇
  2001年   55篇
  2000年   39篇
  1999年   21篇
  1998年   14篇
  1997年   13篇
  1996年   11篇
  1995年   9篇
  1994年   7篇
  1993年   7篇
  1992年   10篇
  1991年   11篇
  1990年   10篇
  1989年   13篇
  1988年   14篇
  1987年   26篇
  1986年   23篇
  1985年   15篇
  1984年   12篇
  1979年   8篇
  1977年   10篇
  1976年   8篇
  1975年   9篇
  1974年   16篇
  1973年   9篇
  1972年   11篇
  1970年   6篇
  1969年   7篇
  1968年   8篇
排序方式: 共有2186条查询结果,搜索用时 15 毫秒
91.
Grb2-associated binder 2 (Gab2) is a recently identified member of the Gab/Daughter of sevenless family of docking proteins, which localize, amplify and integrate signaling pathways activated by various receptors including receptor tyrosine kinases (RTKs). To date, Gab2 signaling has been primarily investigated in hematopoietic cells. Here we report marked overexpression of Gab2 in a subset of breast cancer cell lines relative to normal breast epithelial strains and a trend for increased Gab2 expression in estrogen receptor (ER)-positive lines. Overexpression relative to normal ductal epithelium was also observed in some primary breast cancers. In MCF-7 breast cancer cells Gab2 was markedly tyrosine phosphorylated in response to heregulin and also following EGF, insulin or bFGF administration, indicating that a variety of RTKs implicated in breast cancer development or progression couple to this docking protein. In hormone-responsive breast cancer cells, GAB2 mRNA and protein expression were induced by estradiol in a manner sensitive to the pure anti-estrogen ICI 182780, indicating that this regulation is mediated via the ER. Gab2 therefore represents a novel link between steroid and growth factor signaling in breast cancer, and when overexpressed, may modulate the sensitivity of breast cancer cells to these important growth regulators.  相似文献   
92.
93.
A case of double aneuploidy involving chromosome 21 and Y is reported in an eight-month-old infant with developmental delay and failure to thrive. Patient had all classical phenotypical features of trisomy 21 except, absence of epicanthal folds. The diagnosis was confirmed by cytogenetic study performed on peripheral blood leucocyte culture using G-banding. Literature review revealed only 17 cases of XYY and trisomy 21 reported so far. No such case is reported in Indian literature. Relevant literature is reviwed and possible effects of trisomy 21 on XYY and that of XYY on trisomy 21 has been discussed. A routine chromosomal study even in patient with classical features of Down syndrome has been advocated. Interestingly, our patient also had left to right shunts at atrial and ductal level and tricuspid regurgitation. Given the rarity of the disorder and scanty published data the incidence, phenotype and recurrence risk are difficult to establish.  相似文献   
94.
95.
96.
97.
OBJECTIVE: The aim of this study was to explore the relevance of placental monoamine oxidase at the subcellular level in the etiology of the hyperserotonomic state in preeclampsia-eclampsia. STUDY DESIGN: The study was conducted on placentas from 20 normal pregnant women and 25 women with varied severity of preeclampsia-eclampsia. Placental serotonin and subcellular monoamine oxidase activity were determined. Histochemical localization of monoamine oxidase was done in placental sections and cell isolates. RESULTS: Placental serotonin increases with severity (rsystolic 0.84, rdiastolic 0.83) and monoamine oxidase decreases (rsystolic 0.86, rdiastolic 0.79). Placental monoamine oxidase showed marked changes in preeclampsia-eclampsia. Histochemical localization of monoamine oxidase showed diffused low activity evenly throughout the cytoplasm and nucleus of the syncytiotrophoblastic cells in preeclampsia-eclampsia; in contrast, normal placenta showed high activity in the cytoplasm without any activity in the nucleus of syncytiotrophoblastic cells. Detection of monoamine oxidase activity in nuclei of the placenta in preeclampsia-eclampsia is a novel finding. Monoamine oxidase activity at the subcellular level further strengthens this observation. A severity-dependent decrease was present in the nuclei of placentas with preeclampsia-eclampsia. The use of specific substrates and inhibitors revealed the presence of monoamine oxidase in mitochondria and nucleus. CONCLUSION: The study delineates an impaired catabolism of placental serotonin in preeclampsia-eclampsia. The novel appearance of monoamine oxidase in nuclei in proximity to its normal site and low activity resulting in a hyperserotonomic state may lead to preeclampsia-eclampsia. (Am J Obstet Gynecol 1996;175:1543-50.)  相似文献   
98.
PURPOSE: To compare the efficacy and toxicity of two hypofractionated radiotherapy schedules for the improvement of local symptoms from muscle-invasive bladder cancer. METHODS AND MATERIALS: A multicenter randomized trial was conducted comparing the efficacy and toxicity of two radiotherapy schedules (35 Gy in 10 fractions and 21 Gy in 3 fractions) for symptomatic improvement in patients considered unsuitable for curative treatment through disease stage or comorbidity. The primary outcome measures were overall symptomatic improvement of bladder-related symptoms at 3 months and changes in bladder- and bowel-related symptoms from pretreatment to end-of-treatment and 3-month assessments. Overall symptomatic improvement was defined prospectively as the improvement in one bladder-related symptom of at least one grade at 3 months, with no deterioration in any other bladder-related symptom. RESULTS: Five hundred patients were recruited, but data on symptomatic improvement at 3 months was only available on 272 patients. Of these, 68% achieved symptomatic improvement (71% for 35 Gy, 64% for 21 Gy), with no evidence of a difference in efficacy or toxicity between the two arms. There was no evidence of a difference in survival between the two schedules (hazard ratio [HR] = 0.99, 95% CI 0.82-1.21, p = 0. 933). CONCLUSION: This is the largest prospective trial to date in the palliative treatment of bladder cancer, and provides baseline data against which other results may be compared. The use of 21 Gy in 3 fractions appears as effective as 35 Gy in 10 fractions, although modest differences in survival, symptomatic improvement rates, and toxicity can not be reliably excluded.  相似文献   
99.
100.
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