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   260519篇
  免费   20986篇
  国内免费   8967篇
耳鼻咽喉   2091篇
儿科学   5982篇
妇产科学   4194篇
基础医学   34713篇
口腔科学   5171篇
临床医学   28473篇
内科学   30760篇
皮肤病学   2814篇
神经病学   11726篇
特种医学   8883篇
外国民族医学   90篇
外科学   25368篇
综合类   44581篇
现状与发展   40篇
一般理论   27篇
预防医学   15389篇
眼科学   5354篇
药学   22634篇
  142篇
中国医学   11544篇
肿瘤学   30496篇
  2024年   646篇
  2023年   3447篇
  2022年   7239篇
  2021年   9909篇
  2020年   8968篇
  2019年   8182篇
  2018年   7933篇
  2017年   8247篇
  2016年   9031篇
  2015年   8994篇
  2014年   14492篇
  2013年   15671篇
  2012年   13451篇
  2011年   15079篇
  2010年   12711篇
  2009年   12548篇
  2008年   12454篇
  2007年   13999篇
  2006年   12803篇
  2005年   12200篇
  2004年   10639篇
  2003年   9383篇
  2002年   7403篇
  2001年   6969篇
  2000年   5743篇
  1999年   5255篇
  1998年   3986篇
  1997年   3701篇
  1996年   3609篇
  1995年   3343篇
  1994年   2918篇
  1993年   2585篇
  1992年   2186篇
  1991年   1888篇
  1990年   1570篇
  1989年   1447篇
  1988年   1414篇
  1987年   1103篇
  1986年   851篇
  1985年   986篇
  1984年   924篇
  1983年   580篇
  1982年   739篇
  1981年   617篇
  1980年   522篇
  1979年   449篇
  1978年   354篇
  1977年   272篇
  1976年   300篇
  1975年   187篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
101.
Many epidemiological studies have shown the magnitude and seriousness of mental disorders in developing countries. However, mental health care remains unsatisfactory owing to lack of skilled manpower and many other social and medical priorities. General practitioners and other health personnel can significantly help in extending mental health care provided they receive adequate training during their medical curriculum. With this aim, the Department of Psychiatry at Addis Ababa University runs a 6-week full-time course for undergraduate medical students. Its chief objectives, teaching methods, achievements and shortcomings are discussed in the paper.  相似文献   
102.
胎膜早破并发胎盘早剥的临床分析   总被引:9,自引:0,他引:9  
目的 探讨妊娠晚期胎膜早破并发胎盘早剥的发生率、早期诊断和处理要点。方法 回顾分析2 0 0 1年~2 0 0 4年郑州大学第三附属医院产科分娩的胎膜早破病例,其中并发胎盘早期剥离者8例,与非胎膜早破发生胎盘早剥者进行比较。分析早期诊断和母婴结局。结果 3年分娩总数为4 12 4例,胎膜早破并发胎盘早剥者占全部胎盘早剥的2 8 6 % ,胎膜早破是胎盘早剥的首位发病诱因。胎膜早破并发胎盘早剥的发生率为2 77% ,而非胎膜早破者为0 5 2 % ,两者相比差异有显著性(P <0 0 1)。间断腰痛、血性羊水、胎心异常为常见的临床表现。胎膜早破并发胎盘早剥时围产儿的死亡率为12 5‰,无孕产妇死亡。结论 胎膜早破是胎盘早剥的诱因之一,重视临床表现,并结合B超和胎心监护有助于早期诊断,以降低母儿并发症。  相似文献   
103.
目的探讨MR检查在颈静脉球瘤诊断中的应用价值。方法对15例病变进行回顾性分析,重点分析其部位、信号及其侵袭性表现等情况。结果15例患者中,右侧病变8个(8/15),左侧7个(7/15);肿瘤形态为类圆形或不规则形,12例较大病变不同程度侵犯颈静脉孔区、乳突、岩骨、岩尖、斜坡等处骨质;肿瘤信号欠均匀,12个(12/15)肿块在MR平扫出现“盐和胡椒征”,以“胡椒”表现最为显著;13个肿块(13/13)均有明显强化,其中10个肿块出现“盐和胡椒征”。9例行MRA检查,颈内动脉和颈内静脉不同程度移位和包绕。结论根据肿瘤的部位、“盐和胡椒征”等MR表现,可在手术前正确诊断颈静脉球瘤。  相似文献   
104.
A rapid nonsterile short-term assay has been investigated in which percent inhibition of incorporation of the DNA precursor (3H)-thymidine is measured following exposure of tumor cells to the test drugs. To evaluate the usefulness of the short-term assay in providing a rapid reliable assessment of chemotherapeutic response, the short-term assay was compared with the soft agar clonogenic assay. Sensitivity to five anticancer drugs was compared using three human tumor cell lines (epidermoid carcinoma of the oral cavity, pancreatic carcinoma, and bladder carcinoma). The short-term assay produced results that were similar to results of the clonogenic assay in two of the three tumors tested, for three drugs (cis-platin, doxorubicin, and BCNU), but did not detect responses to two antimetabolites (5-FU and MTX) in any tumor. Further studies of this short-term assay should focus on alkylating agents and other nonantimetabolites.  相似文献   
105.
腹膜转移瘤的影像学诊断   总被引:2,自引:0,他引:2  
目的探讨腹膜转移瘤的影像学表现特点。方法回顾性分析经手术及穿刺活检证实的35例腹膜转移瘤的影像学表现,并与手术结果对照,35例做CT平扫及增强扫描,5例行MR I检查。结果(1)腹膜转移瘤常表现为大量腹水(22/35);(2)腹膜结节状增厚(23/35);(3)大网膜饼形增厚(16/35)和大网膜污垢样改变(12/35);(4)肠系膜污垢样改变(12/35)及结节状改变(9/35);(5)腹腔单发或多发囊性改变,有占位效应(4/35)。结论CT/MR I是发现腹膜转移灶的重要影像学方法。  相似文献   
106.
目的探讨自发性高血压大鼠颈动脉中抑癌基因P53和原癌基因c-jun、c-fos、c-myc mRNA的表达.方法用逆转录聚合酶链式反应检测两种基因的表达水平.正常雄性大鼠作为对照组.结果 SHR颈动脉中,抑癌基因P53和原癌基因c-jun、c-fos、c-myc均有高表达,较WKY差异有显著性(P<0.05).结论自发性高血压大鼠颈动脉组织中抑癌基因P53和原癌基因c-jun、c-fos、c-myc均有高表达,癌基因的活化可能与自发性高血压大鼠颈动脉血管重构有关.  相似文献   
107.
108.
Audiogenic seizures can be induced in DBA/2J mice following intense auditory stimulation. A number of neurotransmitters, including 5-hydroxytryptamine (5-HT), are believed to be involved in mediating this effect since it has been shown previously that depletion of 5-HT or blockade of 5-HT receptors protects DBA/2J mice from these audiogenic seizures. The present study was undertaken to determine whether antagonism of the newly identified 5-HT7 receptor may protect DBA/2J mice from audiogenic seizures by attempting to correlate in vivo potency of compounds with their affinity at the 5-HT7 receptor. All compounds used in the correlation were shown to be antagonists at the 5-HT7 receptor and a statistically significant correlation was observed between 5-HT7 affinity and doses for half-maximal response (ED50) for protection of DBA/2J mice from sound-induced seizures (r = 0.80; P < 0.05). No significant correlation was observed between in vivo activity and affinity at either 5-HT1A, 5-HT2A or 5-HT2C receptors. It is also unlikely that interactions between the 5-ht5 receptor will protect DBA/2J mice from audiogenic seizures since metergoline and mesulergine which are both active in this in vivo model have no affinity for the 5-ht5 receptor. There are similarities between the pharmacology of the 5-HT7 receptor and that of the 5-HT1A receptor, however the correlation between the in vivo potency in DBA/2J mice and 5-HT1A affinity was not significant. Furthermore, the 5-HT1A receptor antagonist WAY 100135 did not protect DBA/2J mice from audiogenic seizures at doses that antagonise 5-HT1A receptor-mediated effects in mice. These data suggest that antagonism of 5-HT7 receptors may protect against audiogenic seizures in DBA/2J mice although a definitive conclusion must await studies with selective 5-HT7 antagonists. Received: 20 March 1997 / Accepted: 10 August 1997  相似文献   
109.
目的通过监测肾移植后病人环孢素A(CsA)全血浓度 ,提出CsA在三联免疫抑制用药方案中的理想治疗窗。方法用特异性荧光偏振免疫法测定CsA全血浓度 ,对521例病人监测3275次 ,按术后时间及临床表现分组比较。结果肾移植后<1 ,、1~3、3~6、6~12个月、1~2和>2年的CsA全血谷浓度的理想治疗窗应分别为250~450、200~400、150~300、100~250、100~200和100~180μg/L。结论CsA全血浓度在上述范围内 ,中毒反应和排异反应明显减少  相似文献   
110.
A cytomorphometric analysis of superficial vaginal cells inwomen in three groups of different types of hormonal concentrationwas made. There were 15 women in each group. Group I was studiedduring a natural cycle, group II under oral contraceptive therapyand group III during an in-vitro fertilization (IVF) stimulationprotocol. Morphometric parameters were measured on an imageanalyser. The area, perimeter and several form factors weremeasured separately for nuclei and cytoplasm. The nucleus:cytoplasmicratio was also determined. The cytoplasmic area was significantlyreduced in group II and was associated with a statisticallysignificant reduction of the nuclear area. The nucleus:cytoplasmicratio appeared significantly increased in group II and reducedin group III. Low oestradiol impregnation obtained with an oralminidosed contraceptive interfered with vaginal cell maturation.High oestradiol concentrations obtained during IVF protocolsinduced marked nuclear pycnosis but did not induce supra-physiologicalcell enlargement. Maximal cell size is genetically regulatedaccording to Driesch's law of volume invariance and hormonalover-stimulation has no effect on cell size. The nucleus:cytoplasmicratio appears to be a powerful parameter reflecting the oppositeeffects of hormones on cell compartments.  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