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   43419篇
  免费   4677篇
  国内免费   3250篇
耳鼻咽喉   413篇
儿科学   561篇
妇产科学   434篇
基础医学   4204篇
口腔科学   659篇
临床医学   5551篇
内科学   5791篇
皮肤病学   344篇
神经病学   1901篇
特种医学   1477篇
外国民族医学   11篇
外科学   4265篇
综合类   9589篇
现状与发展   13篇
一般理论   4篇
预防医学   3500篇
眼科学   1093篇
药学   4749篇
  54篇
中国医学   3582篇
肿瘤学   3151篇
  2024年   211篇
  2023年   793篇
  2022年   2011篇
  2021年   2503篇
  2020年   2030篇
  2019年   1543篇
  2018年   1499篇
  2017年   1458篇
  2016年   1293篇
  2015年   2037篇
  2014年   2636篇
  2013年   2516篇
  2012年   3342篇
  2011年   3772篇
  2010年   2821篇
  2009年   2354篇
  2008年   2641篇
  2007年   2480篇
  2006年   2239篇
  2005年   1954篇
  2004年   1519篇
  2003年   1466篇
  2002年   1249篇
  2001年   1004篇
  2000年   803篇
  1999年   680篇
  1998年   389篇
  1997年   461篇
  1996年   292篇
  1995年   281篇
  1994年   224篇
  1993年   156篇
  1992年   140篇
  1991年   117篇
  1990年   93篇
  1989年   94篇
  1988年   70篇
  1987年   65篇
  1986年   40篇
  1985年   35篇
  1984年   11篇
  1983年   8篇
  1982年   6篇
  1981年   5篇
  1980年   3篇
  1979年   2篇
排序方式: 共有10000条查询结果,搜索用时 12 毫秒
61.
We recently reported on a new fetal rat model of esophageal atresia (EA) with tracheoesophageal fistula (TEF) induced by prenatal exposure to adriamycin (1.75 mg/kg i. p. injected daily to the pregnant dam from the 6th to 9th gestational days). With this treatment regime, many fetuses were resorbed and the number of associated malformations was very high. The present study demonstrates that similar doses of the drug administered only on the 8th and 9th gestational days allow higher fetal survival (9.7 3.9 vs. 6.8 4.7 fetuses per litter, P < 0.01) with a similar incidence of EA-TEF (41.2% vs. 56.4%, n. s.) and decreased occurence of associated anorectal and genitourinary malformations. Since this model is an instrument for further investigation of the disturbed cellular and morphogenetic events leading to EA and TEF, the narrowing of the embryologic window obtained by the present study will allow better focusing of the research on the critical period of time involved.  相似文献   
62.
目的 观察博宁霉素霜剂对牛乳头瘤病毒所致奶牛乳头瘤的疗效。方法 将临床患病牛随机分为2组每次将药物和基质分别涂于试验牛及对照牛乳头皮肤的肿瘤上,每日3次,连续进行10d。结果 试验组2例指状乳头状瘤分别于第6天和第9天完全脱落;4例扁平瘤虽未脱落,但瘤体表面均发生明显的剥蚀;对照组均未发生此类现象。结论 博宁霉索霜剂对奶牛乳头的皮肤无损害作用,但可选择性地使指状乳头瘤脱落,扁平瘤剥蚀、脱皮,呈现良好的治疗作用。  相似文献   
63.
年轻宫颈癌患者卵巢移位临床效果初步分析   总被引:6,自引:0,他引:6  
目的 探讨宫颈癌患者卵巢移位术的临床意义。方法 收集 1 999年 9月~ 2 0 0 2年 1月间北京大学人民医院妇科收治的 1 4例绝经前患者在手术治疗的同时行卵巢移位术的临床资料 ,分析术后患者的更年期症状 ,并与临床特征进行比较。结果 ① 1 4例患者均为绝经前 ,平均年龄 37 36岁 (2 7~ 4 3岁 ) ,宫颈原位癌累腺 2例、Ia 3例、Ib7例、Ⅱa2例 ;② 1 4例患者中 ,双侧卵巢移位术 6例 ,随访 8 3个月 ,5例未出现更年期症状 ;单侧卵巢移位 8例 ,4例无更年期症状 ;③术后辅助治疗 6例 ,均为宫颈浸润癌术后辅助放疗和 /或化疗 ,其中 5例分别于术后 6~ 1 8个月出现更年期症状 ,术后未辅助治疗 8例 ,其中 1例 (4 3岁 )于术后 6个月出现更年期症状。结论 宫颈癌患者术中行卵巢移位术 ,可保留卵巢的功能 ,但术后辅助放疗仍直接影响卵巢的功能 ,卵巢移位术的临床价值 ,有待进一步探讨  相似文献   
64.
BACKGROUND: In nonprimates, organ allografts are often not rejected after withdrawal of immunosuppression. In this study, we examined whether such a phenomenon also occurs in primates. METHODS: Vervet monkeys were transplanted with renal allografts and treated for 60 days with tacrolimus, or tacrolimus plus sirolimus. The drugs were totally withdrawn on day 61. The survival of the monkeys was monitored, and their response to donor- or third party-derived alloantigens was examined in vivo and in vitro. RESULTS: The majority (80-100%) of the grafts survived for at least additional 30 days with no signs of acute rejection. The compromised rejection is donor-specific, because recipient monkeys failed to reject a donor-derived skin graft, but a third-party skin graft was rejected. In vitro mixed lymphocyte reaction and interleukin-2 production in the mixed lymphocyte reaction between the recipients and their donors or between the recipients and a third party had no discernable patterns, and thus did not reflect the in vivo status of the immune system. Although the recipients could not reject the graft acutely after drug withdrawal, the kidney grafts and the donor-derived skin grafts had pathological findings of chronic rejection. CONCLUSIONS: The rejection response of the monkeys to an established graft after withdrawal of immunosuppression is compromised. The compromised rejection is specific and is not due to a permanent alteration of the immune system by the initial drug treatment. The allografts are not inert but have low levels of interaction with the recipient immune system.  相似文献   
65.
The CYP11A gene encodes the cholesterol side-chain cleavage enzyme (P450scc) that catalyzes the first and rate-limiting step for the biosynthesis of sex hormones. A pentanucleotide repeat [(TAAAA)n] polymorphism in the 5' of the CYP11A gene has been reported to be related to the risk of polycystic ovary syndrome, an inherited endocrine disorder characterized by hyperandrogenemia. We investigated the association of this polymorphism with breast cancer risk in a population-based case-control study conducted among Chinese women in Shanghai. Genotype assays were completed for 1015 incident breast cancer cases and 1082 community controls. Three common alleles with 4, 6, or 8 TAAAA repeats were identified in the study population. The frequency of the 8 repeat allele was more common in cases (12.6%) than controls (8.5%) (odds ratio = 1.6, 95% confidence interval = 1.3-1.9; P < 0.0001). Compared to subjects who did not carry this allele, adjusted odds ratios were 1.5 (95% confidence interval = 1.2-1.9) and 2.9 (1.3-6.7) (P for trend, <0.001), respectively, for those who carried one and two copies of this allele. This positive association was observed in both pre- and postmenopausal women and all strata defined by major breast cancer risk factors, including years of menstruation, body mass index, and waist-to-hip ratio. The results from this study indicate that the TAAAA repeat polymorphism near the promoter region of the CYP11A gene may be an important susceptibility factor for breast cancer risk.  相似文献   
66.
67.
孕妇下生殖道解脲脲原体感染与妊娠结局关系的探讨   总被引:2,自引:0,他引:2  
应用聚合酶链反应技术,对216例妊娠12-37周孕妇的宫颈阴道分泌物和其中109例有孕妇分娩时的羊水进行解脲脲原体DNA检测,同时临床观察216例孕妇的妊娠结局。结果:宫颈阴道分泌物UU DNA阳性率为43.06%,宫颈阴道UU DNA阳性组对应的羊水UU检出率明显高于阴性组,两组平均孕周,平均出生体重,平均Apgar评分以及胎儿窘迫,早产,剖宫产,低出生体重儿,低Apgar评分和瘭生儿畸形的发五  相似文献   
68.
镫骨全切除和吸引噪声对豚鼠耳蜗功能与超微结构的影响   总被引:1,自引:0,他引:1  
本实验应用耳蜗电图和扫描、透射电镜等技术观察了6组(44只)豚鼠镫骨全切除后,前庭窗开放时间的长短和听泡内使用吸引器对耳蜗功能和超微结构的影响程度.结果如下:①随前庭窗开放时间的延长、复合蜗神经动作电位(compound action potential.CAP)反应阈进行性提高,开放180min可导致底回部分外毛细胞变性或破坏;②镫骨全切除后,听泡内较长时间地(60min)应用吸引器可引起CAP明显阈移和耳蜗底回部分外毛细胞的不可逆病变;③镫骨未切除时,听泡内吸引60min,仅引起CAP阈移,但外毛细胞未见损伤.结果提示:术中长时间开放前庭窗和鼓室内应用吸引器可能是引起镫骨全切除术后感音神经性聋的因素之一,但鼓室成形术中鼓室内吸引噪声可能因其强度不够大,不足以引起术后感音神经性聋.  相似文献   
69.
Cerebral ischemia induces hyperlocomotion in gerbils, and sensorimotor and cognition dysfunctions in rodents ; however little is known about the spatio-temporal organization of locomotor activity after ischemia. In this study, we continuously (22 h) assessed the spatio-temporal organization of locomotor activity in focal cerebral ischemic mice in an open field with feeding and drinking supplies. To observe the spatio-temporal changes,  相似文献   
70.
金属支架联合立体定向适形放疗治疗肝门部胆管癌   总被引:14,自引:0,他引:14  
目的评价金属支架联合立体定向适形放疗肝门部胆管癌的疗效。方法31例肝门部胆管癌患者行金属支架置入联合立体定向适形放疗,并与23例行单纯支架治疗者进行对比研究。结果联合治疗组生存时间平均为11.1个月;对照组为5.1个月,差异有显著性意义(P<0.01)。结论胆道金属支架置入联合立体定向适形放疗是不能手术肝门部胆管癌的一种有效治疗方法。  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