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   218879篇
  免费   18731篇
  国内免费   7304篇
耳鼻咽喉   1654篇
儿科学   3990篇
妇产科学   1842篇
基础医学   26499篇
口腔科学   3478篇
临床医学   20667篇
内科学   28460篇
皮肤病学   3207篇
神经病学   10144篇
特种医学   4769篇
外国民族医学   28篇
外科学   16635篇
综合类   30719篇
现状与发展   16篇
一般理论   28篇
预防医学   14598篇
眼科学   5004篇
药学   44996篇
  42篇
中国医学   10746篇
肿瘤学   17392篇
  2024年   544篇
  2023年   2839篇
  2022年   5580篇
  2021年   7721篇
  2020年   6952篇
  2019年   7231篇
  2018年   7317篇
  2017年   7386篇
  2016年   7203篇
  2015年   7242篇
  2014年   11602篇
  2013年   15323篇
  2012年   11146篇
  2011年   12344篇
  2010年   10525篇
  2009年   10080篇
  2008年   10072篇
  2007年   11054篇
  2006年   9979篇
  2005年   9688篇
  2004年   8507篇
  2003年   7712篇
  2002年   6684篇
  2001年   6845篇
  2000年   5989篇
  1999年   5084篇
  1998年   3997篇
  1997年   3561篇
  1996年   3167篇
  1995年   2761篇
  1994年   2323篇
  1993年   2031篇
  1992年   1827篇
  1991年   1567篇
  1990年   1312篇
  1989年   1224篇
  1988年   1151篇
  1987年   934篇
  1986年   700篇
  1985年   818篇
  1984年   809篇
  1983年   542篇
  1982年   609篇
  1981年   516篇
  1980年   430篇
  1979年   366篇
  1978年   316篇
  1977年   259篇
  1976年   287篇
  1975年   200篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
971.
Spontaneous ovarian hyperstimulation mimicking an ovarian tumour   总被引:1,自引:1,他引:0  
Ovarian hyperstimulation syndrome in a spontaneous singletonpregnancy is exceedingly rare. We report a case of ovarian hyperstimulationpresenting as bilateral ovarian masses in association with spontaneouspregnancy, occurring in a woman with disturbed liver function.A possible mechanism is discussed.  相似文献   
972.
几种植物来源不同作用机制的抗癌药抗侵袭作用   总被引:4,自引:0,他引:4  
用细胞培养法和癌细胞侵袭实验,观察几种植物来源不同作用机理的抗癌药如紫杉醇、三尖杉酯碱、高三尖杉酯碱及喜树碱[1],对黑色素瘤高转移株B16-BL6细胞及人纤维肉瘤细胞HT-1080的细胞毒作用和抗侵袭作用。结果表明紫杉醇、三尖杉酯碱、高三尖杉酯碱及喜树碱对B16-BL6和HT-1080细胞增殖均有很强的抑制作用。紫杉醇、三尖杉酯碱及高三尖杉酯碱对B16-BL6细胞侵袭和运动也有明显的抑制作用,而喜树碱在同样浓度下对B16-BL6细胞侵袭和运动均无明显抑制。  相似文献   
973.
本文报告了35例双侧唇裂术后唇部继发畸形。这些畸形主要包括唇红缘不整齐、上唇中份厚度不足以及上唇过紧。Z 字成形、V-Y 推进和 Abbe 瓣法常用于矫正这类继发畸形。  相似文献   
974.
胃癌c-erbB-2过度表达与预后的关系   总被引:1,自引:0,他引:1  
探讨c-erbB-2过度表达与胃癌预后的关系。方法:用免疫组化ABC法对103例胃癌手术标本及151个转移淋巴结进行c-erbB-2表达检测。结果:21.4%胃癌手术标本出现阳性表达.其中进展期胃癌、乳头状腺癌、高中分化胃癌及伴淋巴与肝转移的胃癌阳性率显著增高(P<0.05与<0.01);转移淋巴结表达阳性率高于胃癌原发灶(X2=3.7.P>0.05)。高中分化胃癌伴c-erbB-2过度表达者5年生存率显著低于阴性者(P<0.01)。结论:c-erbB-2过度表达可作为胃癌预后估计指标之一。  相似文献   
975.
This case report presents a very rare and long-standing causeof infertility, osseous metaplasia of the endometrium, and describesits successful management by hysteroscopy. A woman with a historyof induced abortion 12 years ago, failed to conceive from thattime on. The infertility work-up was unrevealing except forthe presence of intracavitary calcification on ultrasonography.After diagnostic hysteroscopy, solid bony spicules coveringthe posterior wall of the endometrial cavity were removed bywire loop resectoscope. Histology established the diagnosisof osseous metaplasia of the endometrium. The patient conceivedin her second spontaneous cycle and has an ongoing pregnancyat the time of writing. Hysteroscopy was an effective meansof extracting this heterotopic tissue, thereby re-establishingfertility even after a long period of infertility.  相似文献   
976.
分析了60例垂体腺瘤的CT表现。1例垂体微腺瘤缺乏特异性征象,59例大腺瘤大多数表现典型,诊断依据为肿瘤位置和蝶鞍改变。垂体腺瘤的形态学表现无特异性。应加强对垂体瘤卒中和侵袭征象的认识。对成人鞍区肿瘤的鉴别诊断进行了简短讨论。  相似文献   
977.
Concerns have been raised recently about the possible associationbetween superovulation and ovarian cancer. In order to contributeto the limited literature on this important issue, two casesof ovarian tumours in women who had undergone multiple ovulationinductions are presented. In the first case, the patient hadsecondary anovulatory infertility. She was treated with humanmenopausal gonadotrophin (HMG) alone and in combination withclomiphene citrate or buserelin for six cycles. She then underwentovarian stimulation with buserelin/HMG in the long protocolfor in-vitro fertilization (IVF) and embryo transfer. In preparationfor a new IVF/embryo transfer attempt, 8 months later, the screeningultrasound revealed a cystic formation of the left ovary andan enlargement of the right. During laparotomy, both ovarieswere found to bear large tumours (approximately 6x5x4 cm) whichwere removed. Histological examination showed that they wereepithelial tumours (serous-papillary cystadenomas) of borderlinemalignancy. The patient conceived spontaneously 1.5 years afterthe operation. In the second case, the patient presented withsecondary anovulatory infertility. She underwent ovulation inductionwith clomiphene/HMG and with buserelin/HMG in the long protocol,and intra-uterine insemination with husband's spermatozoa andconceived (singleton pregnancy). She was delivered by Caesareansection, during which a cystic tumour of the left ovary wasremoved. Histological examination revealed a benign mucous cystadenomaof the ovary. In conclusion, the clinical information from thesetwo cases does not support a causal association between ovarianstimulation and ovarian tumours but does potntially supporta facilitating one.  相似文献   
978.
The distribution of mannan binding protein (MBP) in blood donorsera was determined by enzyme-linked immunosorbent assay toestablish normal concentrations. Abnormally low MBP concentrationswere found in 16% (21 out of 135) of female partners and 14%(15 out of 108) of male partners of couples experiencing recurrentmiscarriage, compared with <5% of obstetrically normal controls(P < 0.005). This relationship was even stronger (9.5 versus1.0%) and more significant (P < 0.002) when only subjectspresumed to be homozygous for the mutant allele responsiblefor MBP deficiency were considered. By immunohistochemistry,MBP could be demonstrated in first trimester placenta. We suggestthat low concentrations of MBP within the feto-placental unitincrease susceptibility to fetal loss, possibly via an infection-inducedplacental cytokine imbalance.  相似文献   
979.
Zusammenfassung Bei Frauen von 50 bis 69 Jahren ist in schwedischen Mammographie-Screening-Studien eine Reduktion der Mortalit?t an Brustkrebs langfristig bis zu 30 % beobachtet worden. Bei Frauen von 40 bis 49 Jahren ist eine geringe Verminderung der Sterblichkeit beobachtet worden, die nicht signifikant ist. Die Strahlenbelastung von 2,4 mGy für 2 Ebenen-Mammographie einer Brust führte auch nach Langzeit-Beobachtungen (über 20 Jahre) nicht zu einer Vermehrung neue auftretender Brustkrebsquellen. Die Vorteile des Screenings bezüglich Minderung der Sterblichkeit, h?ufigere Anwendung von brusterhaltenden Therapien und Senkung des durchschnittlichen Tumordurchmessers im Screening auf weniger als die H?lfte des Durchmessers im Vergleich zu Kontrollkollektiven führt dazu: Ein qualit?tsgesichertes Screening ab 50 bis 70 Jahren ist für Deutschland zu empfehlen. Für jüngere Frauen müssen weitere Studien den m?glichen Vorteil des Screenings abkl?ren. Im dezentralen Versorgungssystem sollte das Screening von niedergelassenen ?rzten in Zusammenarbeit mit Krankenh?usern erfolgen, wo die Doppelbefundung, die Abkl?rung unklarer F?lle (Assessment) und die fortlaufende Kosten-Nutzen-Analyse (Evaluation) erfolgen sollte. Qualit?tssicherungszentren, Referenz- und Ausbildungszentren sind zu fordern. Auch die Mammographie der kurativen Versorgung profitiert von einem Screening-Programm. Eingegangen am 29. M?rz 1996 Angenommen am 1. April 1996  相似文献   
980.
Attempts to increase the probability of a successful pregnancyin in-vitro fertilization (IVF) treatment by increasing thenumber of embryos transferred automatically also increase theprobability of multiple pregnancies and their attendant risks.Even where the number of transferred embryos is limited to amaximum of three as in this and other centres, there is a highincidence of twins and triplets. The question therefore ariseswhether the number of transferred embryos should be furtherlimited to a maximum of two in cases where the prognosis isotherwise good. The only objection to this idea is a possiblelowering of pregnancy rate. The present study set out to investigatethis question. No significant lowering of pregnancy rate wasfound, so that limiting the number of transferred embryos totwo where the prognosis is otherwise good has now become standardpractice in our centre. A good IVF prognosis was defined bythe following criteria: first attempt for IVF, less than 37years old, and good embryo development. From 183 patients fulfillingthese criteria, 80 agreed to the transfer of two embryos (group1) and 103 opted for a triple transfer (group 2). Patient characteristicsand embryology results were similar in the two groups. In group1, 34 patients (42.5%) became pregnant and in group 2, 50 (48.5%).This difference is not significant. Similarly, twin pregnancyrates in both groups were high; eight twin pregnancies (23.5%)in group 1 and 12 (24%) in group 2. For the triplet pregnancyrate of 18% (nine triplet pregnancies) in group 2, there wasobviously no parallel in group 1. After thawing about half ofthe cryopreserved embryos and subsequently replacing them, preliminarycumulative pregnancy rates of 52.5% in group 1 and 53.4% ingroup 2 were obtained. Future results from cryopreservationshould provide relatively better outcomes for group 1 sinceall the patients in this group had at least one embryo frozenand fewer embryos replaced in the fresh cycle.  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