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   499篇
  免费   32篇
  国内免费   14篇
儿科学   20篇
妇产科学   7篇
基础医学   41篇
口腔科学   9篇
临床医学   39篇
内科学   132篇
皮肤病学   5篇
神经病学   8篇
特种医学   131篇
外科学   21篇
综合类   7篇
预防医学   38篇
眼科学   3篇
药学   52篇
肿瘤学   32篇
  2022年   2篇
  2021年   2篇
  2019年   4篇
  2018年   3篇
  2017年   7篇
  2016年   4篇
  2015年   11篇
  2014年   9篇
  2013年   10篇
  2012年   13篇
  2011年   18篇
  2010年   11篇
  2009年   22篇
  2008年   20篇
  2007年   23篇
  2006年   17篇
  2005年   22篇
  2004年   14篇
  2003年   12篇
  2002年   10篇
  2001年   14篇
  2000年   7篇
  1999年   13篇
  1998年   19篇
  1997年   26篇
  1996年   24篇
  1995年   12篇
  1994年   17篇
  1993年   7篇
  1992年   7篇
  1991年   2篇
  1990年   8篇
  1989年   12篇
  1988年   9篇
  1987年   10篇
  1986年   10篇
  1985年   15篇
  1984年   6篇
  1983年   17篇
  1982年   17篇
  1981年   15篇
  1980年   10篇
  1979年   3篇
  1978年   6篇
  1977年   11篇
  1976年   7篇
  1974年   1篇
  1973年   2篇
  1939年   2篇
  1935年   1篇
排序方式: 共有545条查询结果,搜索用时 0 毫秒
91.
超低出生体重儿红细胞输注的临床分析   总被引:1,自引:0,他引:1  
探讨超低出生体重(ELBW)儿减少红细胞输注的可能性。方法对1989~1997年9年间256 例超低出生体重儿的红细胞输注进行临床分析。在此期间红细胞输注指征进行了3次制订,对检验样本的采 血量进行了严格的控制,部分病例应用了重组人促红细胞生成素治疗。结果1994年以后有1/4的ELBW儿 不需要输注红细胞,1989~1997年平均输血次数由7次降至2.7次(P<0.01)。按出生体重累计红细胞输注 量由163.5mL/kg降至69.2mL/kg(P<0.01),接受供血者人数由6.3人降至1.5人(P<0.01)。红细胞输注 前的平均红细胞压积比,机械通气者由0.43降至0.34、自主呼吸者由0.41降至0.31。ELBW儿更加不成熟,平 均胎龄由27.4周减至26.0周,平均出生体重由833g降至741g。存活率仍达78%,住院时间没有延长,严重并 发症如视网膜病、动脉导管未闭、脑室出血的发生率没有增加。结论制订严格的红细胞输注指征有助于减少 输血次数和接受供血者人数,且患儿临床耐受良好。  相似文献   
92.
93.
94.
脑康泰胶囊对阿尔茨海默氏病大鼠学习记忆作用的影响   总被引:1,自引:0,他引:1  
目的:观察脑康泰胶囊对阿尔茨海默氏病模型大鼠学习记忆作用的影响。方法:采用脑立体定向颅内注射啉酸所致阿尔第默氏病(Alzheimers disease.AD)大鼠模型的方法。结果:脑康泰胶囊可显著增加强AD大鼠被动学习和主动学习的能力。调节脑组织中单胺类递质含量及血清中相关激素水平,并显著改善AD模型大鼠的脑电图。结论:脑康泰胶囊显著改善AD大鼠学习记忆能力的作用,其机制与其调节中枢递质及激素水平等相关。  相似文献   
95.
Over the past 15 years, the use of β-agonists has declined worldwide. Following the Royal College of Obstetricians and Gynaecologists guidelines in 2002, clinicians in the UK and beyond were faced with the dilemma of continuing to use β-agonists, desist from using tocolytic therapy completely or choosing to change to atosiban or calcium channel blockers (CCBs). While grade A level 1 evidence exists to show that atosiban is significantly more efficacious than placebo and significantly safer than β-agonists for the treatment of spontaneous preterm labour, the evidence for CCBs, such as nifedipine, is much less robust and no placebo-controlled trials have been performed. Published studies on nifedipine are largely investigator-led studies of small sample size, which lack sufficient power. As a result, most of the evidence has been based on meta-analyses of these studies, which look retrospectively at pooled data and are only as good as the quality of the studies included. In light of this, a tool was developed to produce a systematic review of studies on tocolytic effectiveness, which can and should be applied to all tocolytics and which considered both method- and topic-specific markers of quality. In the process of applying this tool to nifedipine, an extensive literature search identified 31 studies for a systematic review of the quality of nifedipine studies assessed by eight paired reviewers with wide experience in the subject of spontaneous preterm labour and preterm birth. Forty topic- and method-specific items of quality were assessed. The paucity of good quality studies of nifedipine used for the treatment of spontaneous preterm labour should be highlighted in meta-analyses or systematic reviews, which measure efficacy and should limit and influence the degree to which recommendations and guidelines are made on the basis of such studies.  相似文献   
96.
华蟾蜍毒素对离体豚鼠输精管的作用   总被引:3,自引:0,他引:3  
韩永晶  张力  崔荣芬 《药学学报》1992,27(4):252-255
华蟾蜍毒素(华蟾素)使离体豚鼠输精管产生剂量依赖性收缩反应,利血平化豚鼠输精管及冷藏输精管对华蟾素反应减弱。给酚妥拉明、维拉帕米后,输精管对华蟾素反应均受抑制,溴苄胺可使反应潜伏期缩短。结果提示华蟾素收缩输精管反应可能与其促进肾上腺素能神经末稍NA释放有关。  相似文献   
97.
Little is known about the prognostic impact of chromosome aberrations in breast cancer. The aim of our study was to determine whether genomic aberrations of prognostic relevance can be identified in the context of a clinical study using molecular cytogenetics. Paraffin-embedded tumor samples of 44 patients with high-risk stage II/III breast cancer were analyzed by comparative genomic hybridization. All patients received identical therapy including dose-escalated chemotherapy followed by peripheral blood stem cell transplantation. The most frequent chromosomal aberrations were gains on chromosome arms 17q (24 cases), 1q (21 cases), 8q (17 cases), 20q (13 cases), 6p (9 cases) as well as losses on chromosome arms 13q (25 cases), 11q (20 cases), 5q (11 cases), 6q (11 cases), 9p (10 cases), 18q (10 cases), 8p (9 cases) and 16q (9 cases). In univariate analysis, the correlation with the clinical outcome revealed a higher risk for patients with tumors exhibiting 13q losses and a reduced risk for tumors exhibiting 16q losses (p = 0.020), 6q losses (p = 0.041) and estrogen-receptor positivity (0.051). In multivariate analysis using the Cox model, only the loss of 16q exhibited borderline significance (p = 0.065). These data show that comparative genomic hybridization can be performed in the context of a clinical trial. In our subgroup of high-risk breast cancer patients, chromosomal aberrations were valuable prognostic parameters.  相似文献   
98.
Seasonal changes in developmental stages, condition factor (CF), gonadosomatic index, and plasma vitellogenin (Vtg) concentrations in male and female hornyhead turbot were examined at the wastewater outfall (T1) of the Orange County Sanitation District, and two farfield sites T11 (7.7 km northwest of the outfall) and Dana Point (35 km south of the outfall) between February 2005 and May 2006. Fish collected from the three sites exhibited male-oriented sex ratios. With few exceptions, developmental stages, CF, and GSI of both genders and plasma Vtg concentrations of females were not significantly different in samples collected from different sites at the same sampling period. More advanced gonad developmental stages and higher plasma Vtg concentrations in females were observed in August, indicating the seasonality of the reproductive cycle for this species. Plasma Vtg concentrations in males were observed in all of the sampling sites with the highest prevalence at T11 relative to T1 and Dana Point. The Vtg expression in males from the three sampling sites indicated widespread exposure to estrogenic compounds in waters of coastal California. However, the histopathological and reproductive relevance of the responses appeared to be insignificant and may not affect the population in these locations.  相似文献   
99.
100.
PURPOSE: To prospectively compare cytogenetic and molecular cytogenetic analysis for the detection of the most relevant chromosome abnormalities in a large series of patients with acute myeloid leukemia (AML). PATIENTS AND METHODS: Two hundred forty consecutive adult patients with AML entered onto the multicenter treatment trial AML HD93 were studied. Chromosome banding and fluorescence in situ hybridization (FISH) applying a comprehensive set of genomic DNA probes were performed in a single reference laboratory. RESULTS: Two cases of inv(16), three cases of t(11q23), and three cases of t(8;21)var were only detected by molecular cytogenetics. By FISH, aberrations were identified in three cases with normal karyotypes: inv(16), -Y (in a patient with low metaphase yield on chromosome banding) and a 12p microdeletion. Additional aneuploidies, in particular +8q and +11q, were diagnosed by FISH; however, virtually all these aberrations occurred in patients with complex karyotypes or as an additional abnormality in leukemias with an AML-specific translocation. Finally, aberrations were detected by FISH in eight of 14 patients with no assessable metaphases. CONCLUSION: In most cases of AML, conventional cytogenetic study reliably detects chromosomal abnormalities, and this method should not be replaced by FISH. FISH should be used as a complementary method for the detection of more subtle abnormalities, such as inv(16) and t(11q23), in all patients with newly diagnosed AML and for suspected t(8;21)var. Furthermore, molecular cytogenetics using this comprehensive set of DNA probes provides a valuable diagnostic tool for patients with poor chromosome morphology, low or no yields of metaphase cells, or both.  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