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   2592篇
  免费   95篇
  国内免费   27篇
耳鼻咽喉   1篇
儿科学   224篇
妇产科学   673篇
基础医学   155篇
临床医学   190篇
内科学   81篇
皮肤病学   30篇
神经病学   47篇
特种医学   26篇
外科学   129篇
综合类   407篇
预防医学   536篇
药学   175篇
中国医学   35篇
肿瘤学   5篇
  2024年   3篇
  2023年   18篇
  2022年   69篇
  2021年   88篇
  2020年   65篇
  2019年   75篇
  2018年   67篇
  2017年   79篇
  2016年   92篇
  2015年   63篇
  2014年   214篇
  2013年   233篇
  2012年   150篇
  2011年   192篇
  2010年   180篇
  2009年   106篇
  2008年   117篇
  2007年   121篇
  2006年   118篇
  2005年   104篇
  2004年   106篇
  2003年   68篇
  2002年   51篇
  2001年   37篇
  2000年   42篇
  1999年   20篇
  1998年   25篇
  1997年   16篇
  1996年   17篇
  1995年   16篇
  1994年   19篇
  1993年   16篇
  1992年   9篇
  1991年   7篇
  1990年   13篇
  1989年   12篇
  1988年   13篇
  1987年   8篇
  1986年   7篇
  1985年   12篇
  1984年   9篇
  1983年   7篇
  1982年   8篇
  1981年   8篇
  1980年   3篇
  1979年   2篇
  1978年   1篇
  1976年   6篇
  1973年   1篇
  1972年   1篇
排序方式: 共有2714条查询结果,搜索用时 15 毫秒
101.
102.

Objective(s)

Interest has increased regarding the issue of contraception in transplant recipients. The purpose of this study was to assess birth control selection and the role of contraceptive counseling sessions in female kidney transplant (KT) and liver transplant (LT) recipients.

Study Design

A cross-sectional single-center survey study of 217 female organ recipients (KT, 137 and LT, 80), aged 18–45 years, met the study criteria. Patients were asked 43 questions regarding their pre- and posttransplantation use of contraceptive methods, birth control awareness, contraception counseling and the factors determining the selection of effective contraception (hormonal contraception, intrauterine devices and female sterilization).

Results

Thirty-three percent (5/15) of patients who had undergone the transplantation within 1 year prior to study inclusion were unaware of the necessity to use contraception. Both of the groups studied did not differ significantly in terms of the rates of pre- and posttransplantation consultations on effective contraception (KT: 26% vs. 34%; p=0.153 and LT 38% vs. 35%; p=0.729). Effective posttransplantation contraception was used by one in three patients, as indicated by posttransplantation consultations (KT: 30% vs. LT: 29%; p=0.910). The following factors affected the posttransplantation use of effective contraception: the presence of posttransplantation counseling on effective contraception [odds ratio (OR): 6.67; 95% confidence interval (CI): 2.12–20.1] and infrequent sexual activity prior to transplantation (OR: 0.56; 95% CI: 0.35–0.89).

Conclusion(s)

The selection of effective contraception in KT and LT recipients remain suboptimal. Despite the low numbers of women who received contraceptive counseling in this study, consultation was nonetheless associated with choosing an effective method of contraception.

Implication

Current literature and data regarding contraception among female organ transplant recipients remain limited and are predominantly limited to a single population. The purpose of the study was to assess the level of satisfaction and the reasons underlying birth control selection in female kidney and LT recipients.  相似文献   
103.
目的探讨正常形态精子比率对宫腔内人工授精(IUI)临床妊娠率的影响。方法回顾分析328个周期宫腔内人工授精临床资料,根据男方精子形态学检查结果分为三组:正常形态精子百分率≥4%、2%~〈4%、〈2%,比较各组间精液处理前后精子浓度、活力、前向运动精子总数以及IUI临床妊娠率。结果处理前精子浓度、活力及前向运动精子总数各组间比较无显著性差异(P〉0.05),处理后精子浓度、活力、前向运动精子总数各组间比较有显著性差异(P〈0.05),≥4%、2%~〈4%、〈2%各组临床妊娠率分别为19.5%、17.9%、2.6%,有显著性差异(P〈0.05)。结论正常形态精子比率影响IUI临床妊娠率,正常形态精子百分率≥2%可获得较满意的临床妊娠率。  相似文献   
104.
目的:探讨宫内节育器异位的原因、诊断方法,分析IUD异位的危险因素、处理方法。方法回顾性分析42例节育器异位的临床资料。结果爱母环占61.90%(26/42),O形环占28.57%(12/42),T环形占4.76%(21/42),吉妮环占4.76%(2/42);爱母环发生异位的机率明显高于其它类型节育器;位于子宫肌层内30例,穿破浆膜层4例;子宫外异位:位于盆腔内6例,阔韧带后叶3例;爱母环的一条金属臂穿入乙状结肠1例,穿入宫旁1例,1例位于右上腹大网膜内,1例位于肠管表面。取器方式利用宫腔镜、腹腔镜、宫腹腔镜联合、膀胱镜及开腹等方式,均成功。有随访记录的14例占33.4%,其中,术后1+月随访3例占7.1%,1年内随访者有12例占21.4%,3年内随访者2例占4.8%,无随访者28例占66.7%。节育环异位穿孔率无随访者高于有随访记录者。在节育器异位患者中,上环后有再次妊娠15例占35.7%。结论选择合适的节育器,适宜的安环时间可减少节育器异位的发生。充分术前评估,选择适宜的手术方式、及时、合理转换术式是取环成功的关键。  相似文献   
105.
目的探讨三维超声造影(3D-CEUS)在诊断宫腔粘中的应用价值。方法对71例经阴道三维超声(3DTVS)检查提示怀疑宫腔粘连的患者行宫腔镜检查,以宫腔镜检查为金标准,比较两者诊断宫腔粘连的准确率;在月经20~23d对3D-TVS诊断疑似宫腔粘连的患者行声诺维(sonovue)3D-CEUS检查,获得内膜厚度、容积(V)、回声强度(MG)、血管指数(VI)、血流指数(FI)、血管血流综合指数(VFI)等相关指标;对经sonovue 3D-CEUS疑似宫腔粘连的的患者,于月经第3~7天行宫腔镜检查,回顾性分析不同程度宫腔粘连的患者与3D-CEUS获得的V、MG、VI、FI、VFI值的关系。结果 3DTVS与宫腔镜比较,3D-TVS诊断宫腔粘连的符合率是90.14%;宫腔镜检查轻、中、重度3组,各组间子宫内膜厚度和容积比较均有显著性差异(P0.05);轻度和重度组子宫内膜MG分别(39.75±7.46)、(45.64±6.10),其差异具有统计学意义(P0.05);轻度和重度组组间子宫内膜VI、FI、VFI相比较,差异均具有统计学意义(P0.05),而中度组与其它两组比较均无显著性差异(P0.05)。经静脉推注30mg sonovue造影剂后,3D-CEUS检查结果显示:3组内膜血流VI值分别较造影前显著增加(P0.001),轻度和重度、中度和重度组的内膜VI、FI、VFI相比较,差异均具有统计学意义(P0.05)。结论 3DCEUS检查不仅可以较准确的诊断宫腔粘连,而且通过计算机辅助分析技术对宫腔粘连患者子宫内膜V、MG、VI、FI、VFI进行定量测量,对宫腔粘连的程度有更客观的评价。  相似文献   
106.
107.
The aim of this study was to analyze factors influencing the growth pattern of children from birth to 18 months. A longitudinal prospective study was conducted in three maternity wards in Southern Benin. Inclusion took place between June 2007 and July 2008; children were followed-up until 18 months of age. Height-for-age and weight-for-height Z-scores were computed using the newborn's anthropometric measurements taken at delivery, every month up to 6 months and then quarterly. Infant and young child feeding (IYCF) practices and malarial morbidity were recorded. Gestational age was estimated using the Ballard method; William's sex-specific reference curve of birth weight-for-gestational-age was used to determine intrauterine growth retardation (IUGR). Analyses were performed on 520 children using a linear mixed model. Low birth weight (coef = −0.43; p = 0.002), IUGR (coef = −0.49; p < 0.001), maternal short stature (coef = −0.25; p = 0.001) and maternal low weight status (coef = −0.19; p = 0.006) were significantly associated with growth impairment. Only LBW (coef = −0.28; p = 0.05) and maternal low weight status (coef = −0.23; p = 0.004) were associated with wasting. A good IYCF score was positively associated with weight gain (coef = 0.14; p < 0.001) whereas we found a paradoxical association with length (coef = −0.18; p < 0.001). Malaria morbidity was not associated with growth. LBW, IUGR and maternal low weight status and height were important determinants of children's growth. These results reinforce and justify continuing public health initiatives to fight IUGR and LBW and break the intergenerational cycle of malnutrition.  相似文献   
108.
BackgroundThis study aimed to test the hypothesis that long non-coding RNA (lncRNA) colorectal neoplasia differentially expressed (CRNDE) could exacerbate brain injury caused by intrauterine infection in neonatal rats.MethodsIntrauterine infection was induced in pregnant rats by lipopolysaccharide (LPS). After delivery, newborn rats with brain injury caused by intrauterine infection were randomly divided into control, control shRNA, and CRNDE shRNA groups. CRNDE expression in serum and amniotic fluid of pregnant rats and neonatal brain tissues were determined by quantitative real-time PCR (qRT-PCR). Morris water maze (MWM) task was used to test the spatial learning and memory ability. Histological examination and apoptosis detection were performed by hematoxylin and eosin (H&E) and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining, respectively. Immunohistochemistry was conducted to evaluate the activation of astrocytes and microglia.ResultsLncRNA CRNDE was highly expressed in serum and amniotic fluid of maternal rats and in brain tissues of offspring rats. Furthermore, shRNA-mediated CRNDE downregulation could rescue the spatial learning and memory ability, improve brain histopathological changes and cell death, and inhibit the activation of astrocytes and microglia caused by LPS.ConclusionCRNDE silencing possessed a cerebral protective effect in neonatal rats with brain injury caused by interauterine infection.  相似文献   
109.
The coronavirus disease 2019 (COVID-19) has been a worldwide pandemic diseases, nearly 400,000 people died at now. The data of status of pregnant women and neonates after infection of severe acute respiratory syndrome coronavirus 2 (SARS-COV-2) is limited. We report a case of pregnant woman in her third trimester with critical COVID-19, and amniotic fluid, umbilical cord blood, placenta, and neonatal gastric fluid were retained during cesarean section. The SARS-COV-2 nucleic acid test results of these specimens were negative. There is no evidence of intrauterine vertical transmission during delivery in the third trimester, but the data are limited and need to be further explored.  相似文献   
110.

Introduction

The proper function of the fetal heart is indispensable for the fetal development and the normal fetal growth. For prenatal medicine, Doppler sonography offers the possibility of a non-invasive method to examine the fetal cardiovascular function under normal and pathological circumstances. The role of the Doppler sonography is to identify those fetuses who have a high risk factor for developing a pre- or intrapartual asphyxia and therefore have to be delivered promptly. This study aimed at evaluating the clinical value of the intracardiac Doppler sonography (IDS) and at scrutinizing its usefulness during the supervision of the pregnancy of intrauterine growth restricted (IUGR) fetuses.

Materials and methods

In a prospective research at the Medical School of Hanover, fetal IDS was applied to 174 pregnant women between the 21 and 37 weeks of gestation (WG). The e-wave and the a-wave, the E/A ratio, and the TVI (time velocity integral) were measured at the atrioventricular (AV) valves. The PV (peak velocity) as well as the TVI were determined at both the aortic and the pulmonary valve. Normal range curves were compiled for all measured parameters.

Results

Alongside a control group with untroubled gravidity, which consisted of 153 patients, IUGR fetuses, who formed a collective of 21 patients, were Doppler sonographically examined.While the gestational age advanced, an increase of both the e-wave and the a-wave above the AV-valves could be ascertained, which lead to an E/A ratio <1. Above the semilunar valves there was indicated a slight steady increase of the TPV, the PV as well as the TVI. Normal range curves, which largely correspond to those described in the literature, were compiled for the collective of the pregnancies without pathological findings (n = 153). In comparison to the standard collective, there were no significant differences from the collective of the growth restricted fetuses (n = 21).

Conclusion

A temporal informational advantage of pathological intracardiac Doppler values for high risk pregnancies (IUGR) could not be retraced in the examined collective.Doppler sonography traces acute and chronic deficits, which are indicated by hemodynamic changes of the fetus’s blood supply. The clinical importance of IDS as regards dystrophic fetuses has to be ascertained in continuative studies: In the stage of compensatory placental insufficiency (IUGR, arterial Doppler without ARED-flow, venous Doppler without pathological findings) the IDS cannot provide an informational advantage. Contrastingly, the diagnostic potential of the IDS as a screening method of fetal cardiac insufficiency during decompensative placental insufficiency (IUGR, arterial Doppler with ARED-flow, venous Doppler normal or pathological) remains indistinct and should therefore be prospectively evaluated within this high risk group and contrastingly compared to the significance of the venous Doppler sonography (informational advantage?).
  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