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   7279篇
  免费   436篇
  国内免费   97篇
儿科学   25篇
妇产科学   1647篇
基础医学   1364篇
口腔科学   2篇
临床医学   430篇
内科学   142篇
皮肤病学   110篇
神经病学   20篇
特种医学   49篇
外国民族医学   1篇
外科学   1703篇
综合类   1049篇
一般理论   6篇
预防医学   479篇
眼科学   1篇
药学   256篇
  3篇
中国医学   474篇
肿瘤学   51篇
  2024年   19篇
  2023年   72篇
  2022年   115篇
  2021年   264篇
  2020年   302篇
  2019年   239篇
  2018年   197篇
  2017年   254篇
  2016年   226篇
  2015年   198篇
  2014年   426篇
  2013年   524篇
  2012年   401篇
  2011年   376篇
  2010年   353篇
  2009年   343篇
  2008年   327篇
  2007年   324篇
  2006年   358篇
  2005年   280篇
  2004年   271篇
  2003年   273篇
  2002年   236篇
  2001年   147篇
  2000年   147篇
  1999年   137篇
  1998年   90篇
  1997年   85篇
  1996年   110篇
  1995年   110篇
  1994年   69篇
  1993年   68篇
  1992年   57篇
  1991年   61篇
  1990年   40篇
  1989年   51篇
  1988年   54篇
  1987年   30篇
  1986年   15篇
  1985年   26篇
  1984年   23篇
  1983年   22篇
  1982年   15篇
  1981年   19篇
  1980年   24篇
  1979年   17篇
  1978年   9篇
  1976年   3篇
  1974年   3篇
  1972年   1篇
排序方式: 共有7812条查询结果,搜索用时 0 毫秒
1.
2.
目的 采用Meta分析对比四维子宫输卵管超声造影(4D-HyCoSy)与子宫输卵管造影(HSG)评估输卵管通畅性的效能。方法 系统搜索PubMed、Cochrane Library、Embase、Web of Science、中国生物医学文献数据库、中国知网、万方医学网及维普数据库中建库至今有关4D-HyCoSy和/或HSG评估输卵管通畅性的文献。由2名研究人员依据纳入标准和排除标准筛选文献并提取信息;分别计算4D-HyCoSy和HSG评估输卵管通畅性的合并敏感度(SEN)、特异度(SPE)及诊断比值比(DOR),绘制综合受试者工作特征(SROC)曲线,获得曲线下面积(AUC),并以Medcalc 19.1.1统计软件比较AUC。结果 最终纳入19篇文献、1 358例疑似输卵管因素导致不孕患者,其中4篇同时采用4D-HyCoSy及HSG评估输卵管通畅性,10篇仅以4D-HyCoSy评估,5篇仅以HSG评估。Meta分析结果显示,4D-HyCoSy评估输卵管通畅性的合并SEN、SPE及DOR分别为0.92[95%CI(0.91,0.94)]、0.91[95%CI(0.89,0.93)]及115.06[95%CI(54.23,224.10)];HSG评估输卵管通畅性的合并SEN、SPE及DOR分别为0.84[95%CI(0.81,0.87)]、0.80[95%CI(0.76,0.83)]及28.64[95%CI(10.08,81.35)]。4D-HyCoSy评估输卵管通畅性的AUC为0.98[95%CI(0.96,0.99)],HSG为0.93[95%CI(0.90,0.95)],差异有统计学意义(Z=6.97,P<0.01)。结论 4D-HyCoSy评估输卵管通畅性的效能高于HSG。  相似文献   
3.
Male infertility accounts for 50% of the causes of infertile couples, being more than 30% of unknown etiology. In these cases, empiric treatment can be an option prior to the application of assisted reproduction techniques. Empiric treatment can be categorized as hormonal, such as gonadotropins, antiestrogens and aromatase inhibitors, and antioxidant, with vitamins, trace elements and carnitine, among others. Although scientifically acceptable evidence is limited due to the absence of large randomized and controlled clinical trials, recent systematic reviews and meta-analyses show that treatment with gonadotropins, antiestrogens and antioxidants increases pregnancy and live birth rates and improves seminal parameters. Empiric medical treatment for idiopathic infertility can be considered in specific cases in order to improve semen quality and spontaneous fertility.  相似文献   
4.
Key words:anTraditional Chinese Medicine has been used to treat various diseases in Chinathousands of years before the introduction of Western Medicine and practices.Inrecent years it has also been used to treat the immunological infertility caused byAs A…  相似文献   
5.
Summary:  Three chromosomal rearrangements: a balanced reciprocal translocation, t(14;10) (q22;q13), a Y-autosome translocation, t(Y;16) (q11;p13) and a deleted Y chromosome, Yq- were detected among 100 infertile men. The autosomal translocation, associated with oligozoospermia was found to be familial with various effects on the female carriers and the proband's father. The patients with the chromosome Y abberations were found to be azoospermic and might have lost the genes necessary for normal sperma-togenesis.
Zusammenfassung:  Unter 100 infertilen Männern wurden drei Chromosomenneuan-ordnungen entdeckt: eine balancierte reziproke Translokation, t(14;10) (q22;q13), eine Y-autosome Translokation, t(Y;16) (q11;p13) und eine Deletion des Y-Chromosoms, Yq-. Die autosomale Translokation bei Oligozoospermie zeigte sich familiär mit verschiedenen Auswirkungen bei den weiblichen Überträgern und dem Vater des Probanden. Die Patien-ten mit chromosomalen Y-Aberrational wiesen eine Azoospermie auf und scheinen die zur normalen Spermatogenese notwendigen Gene verloren zu haben.  相似文献   
6.
Damage to the genetic component of spermatozoa seems to play the main role in a majority of cases where current approaches fail to reveal the specific cause of male infertility. In this study, we compared semen quality in men assigned to two defined groups: men from couples with unexplained infertility – idiopathic infertility (A) and young men with no experiences of infertility (B). All samples were examined by standard ejaculate analysis and sperm chromatin structure assay (SCSA). Sperm chromatin damage was significantly higher in men from group A than in those from group B. Similar results were obtained by comparison of men from group A (all men were normozoospermic) with normozoospermic men from group B. According to these results, we can suppose that chromatin disorders may be the causal factor of subfertility or infertility in some of these men. No evidence for a strong association between chromatin disorders and standard parameters of ejaculates was found. We failed to confirm a relationship between smoking and sperm quality in men from any of the investigated groups. SCSA is a method that facilitates the identification of infertile men who otherwise show normal semen variables.  相似文献   
7.
132例男性不育患者遗传学病因分析   总被引:3,自引:0,他引:3  
目的:对男性不育患者进行遗传学病因分析,并探讨其遗传效应。方法:采取132例男性不育患者外周血进行染色体核型分析。结果:132例男性不育患者中,染色体异常24例,染色体变异22例。其中大Y20例,47,XXY18例,45.XY,t(13;14)3例,小Y和46,XY,inv(9)各2例,46,XY,t(9;22)1例。结论:染色体异常是男性不育的重要原因,并建议男性不育患者进行基因诊断,以便确诊是否属于遗传病,为生育提供指导,避免盲目治疗。  相似文献   
8.
Receiver operating characteristic curves and accuracy parameters were computed for traditional sperm characteristics (concentration, motility, morphology) and the number of peroxidase negative cells, and the concentration of adenosine triphosphate (ATP) in semen from populations of fertile and infertile men, and men who achieved a pregnancy after varicocele treatment. The percentage and concentration per millilitre of spermatozoa with rapid linear progressive motility, and the ATP concentration, provided the best discrimination between fertile and treated fertile from infertile men. The misclassification rate was higher for sperm morphology, total progressive motility and viability, whereas sperm concentration and the total sperm count per ejaculate had the worst discriminating power. The number of peroxidase negative cells per 100 spermatozoa was highly specific in identifying men who achieved pregnancy after varicocele treatment. The lower limit of normality of sperm characteristics was remarkably different between fertile men and men achieving pregnancy after treatment or during infertility work-up.  相似文献   
9.
This study was aimed at assessing the outcome of in-vitro fertilization(IVF) and embryo transfer in patients with polycystic ovariansyndrome (PCOS). The results of IVF and embryo transfer in PCOSpatients (PCOS group, 78 cycles of 26 patients) were comparedwith those of a control group (423 cycles in 202 patients withoutmale factor; age and ovarian stimulation protocol were matched).Although the pregnancy rate per transfer was not different inthe two groups of patients (25 versus 34%, PCOS versus controlgroup), the PCOS group had a significantly lower pregnancy rateper follicle aspiration (19 versus 31%, P < 0.05). A notableresult was a significantly higher incidence of embryo transfercancellations in the PCOS group (22 versus 8%, P < 0.01),which resulted from unpredictable failure of either oocyte recoveryor fertilization. The incidence of unexplained complete failureof fertilization was significantly higher in the PCOS group(18 versus 5%, P < 0.01). These results may reflect a reducedquality of the oocytes in the PCOS group, and there was a subgroupof PCOS patients who repeatedly produced poor results of treatment.Although the ovarian stimulation regimen best suited to PCOSpatients remains to be determined, special care should be takenduring ovarian stimulation, especially when the PCOS patientshad experienced unexplained failure of oocyte recovery or fertilizationin the previous treatment cycle(s).  相似文献   
10.
Seminal culture and leucocyte elastase measurements were undertaken on samples from 30 men attending an infertility clinic. Elastase levels over 1000 ng ml-1 were obtained in 14 men and positive bacterial culture in 11 men, but there was no correlation between these two sets of measurements. While granulocyte elastase measurement in semen may reflect inflammation, our study suggests that it cannot be used as a simple marker of infection particularly in a population such as ours where the prevalence of prostatitis and genital infection is low.  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