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   26343篇
  免费   1411篇
  国内免费   57篇
耳鼻咽喉   410篇
儿科学   1151篇
妇产科学   873篇
基础医学   4273篇
口腔科学   579篇
临床医学   2142篇
内科学   5247篇
皮肤病学   537篇
神经病学   2584篇
特种医学   1070篇
外国民族医学   14篇
外科学   3776篇
综合类   119篇
一般理论   3篇
预防医学   1367篇
眼科学   502篇
药学   1373篇
中国医学   19篇
肿瘤学   1772篇
  2022年   212篇
  2021年   361篇
  2020年   237篇
  2019年   329篇
  2018年   415篇
  2017年   347篇
  2016年   486篇
  2015年   472篇
  2014年   641篇
  2013年   825篇
  2012年   1194篇
  2011年   1267篇
  2010年   625篇
  2009年   681篇
  2008年   1154篇
  2007年   1241篇
  2006年   1161篇
  2005年   1179篇
  2004年   983篇
  2003年   989篇
  2002年   904篇
  2001年   906篇
  2000年   939篇
  1999年   797篇
  1998年   349篇
  1997年   270篇
  1996年   221篇
  1995年   202篇
  1994年   180篇
  1993年   181篇
  1992年   487篇
  1991年   509篇
  1990年   488篇
  1989年   417篇
  1988年   393篇
  1987年   405篇
  1986年   399篇
  1985年   396篇
  1984年   271篇
  1983年   215篇
  1982年   139篇
  1981年   143篇
  1979年   263篇
  1978年   185篇
  1977年   156篇
  1976年   153篇
  1975年   164篇
  1974年   193篇
  1973年   169篇
  1972年   156篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
141.
We retrospectively reviewed records of 551 patients with clinical Stage C prostatic adenocarcinoma treated with 60 to 70 Gy external beam radiation. Elective pelvic node irradiation was given to 247 patients (45%). Follow-up for all surviving patients ranged from 16 to 201 months (median, 6.5 years; mean, 7 years). The 5-, 10-, and 15-year uncorrected actuarial survival rates were 72%, 47%, and 27%, respectively. Disease-free survival rates were 59%, 46%, and 40% at the corresponding times. Actuarial local control rates were 88%, 81%, and 75% at 5, 10, and 15 years, respectively. Disease-free survival was adversely affected by high pathologic grade, disease fixed to the pelvic sidewall, invasion of the bladder, prior transurethral resection, hydronephrosis, and elevated serum levels of prostatic acid phosphatase and creatinine. Elective pelvic node irradiation did not improve the outcome. Complications of treatment were acceptable: minor anorectal and/or urinary symptoms, 11%; mild to moderate complications, 19%; serious problems requiring surgery, 3%. It is concluded that localized, high-energy external beam irradiation provides excellent local control of disease, low morbidity, and 5-, 10-, and 15-year survival rates that have not been rivaled by other treatment.  相似文献   
142.
ZusammenfassungHintergrund Lernstörungen werden zunehmend auf Defizite bei der Sprachwahrnehmung und diese wiederum auf eine Verlangsamung der auditiven Verarbeitungsgeschwindigkeit zurückgeführt. In der Studie wird untersucht, ob sich bei Kindern mit Schulproblemen sprachliche Leistungen durch ein Zeitverarbeitungstraining verbessern lassen.Patienten und Methoden Bei 21 Kindern mit spezifischen Lernstörungen wurden über 8 Wochen Ordnungsschwelle und Richtungshören trainiert und im Vergleich zu einer Kontrollgruppe (n=21) Sprachleistungen bis 6 Monate danach überprüft.Ergebnisse Leistungssteigerungen wurden hinsichtlich der Ordnungsschwelle, nicht aber der sprachlichen Fähigkeiten beobachtet. Die Eltern schätzten die Wirkung des Trainings eher positiv ein.Schlussfolgerungen Ein Zeitverarbeitungstraining verbessert unmittelbar geübte Leistungen, nicht aber sprachliche Fähigkeiten. Von den Eltern wahrgenommene Verbesserungen sind nicht objektivierbar und als unspezifische Effekte zu bewerten. Die Ergebnisse sprechen insgesamt gegen die Wirksamkeit eines Zeitverarbeitungstrainings bei Kindern mit Schulschwierigkeiten.  相似文献   
143.
144.
Primary osteosarcoma of the liver   总被引:1,自引:0,他引:1  
Extraskeletal osteosarcomas are infrequent, and those that arise within parenchymal organs are very rare indeed. This case of a 71-year-old man with a primary osteosarcoma of the liver is the second reported in man. Pathologic findings, including ultrastructural features, at surgery and autopsy are presented. The differential diagnosis is discussed in detail.  相似文献   
145.
The accumulation of blood monocytes at sites of predilection of the vessel wall is an early cellular event of atherogenesis. Proteins of the vessel wall may facilitate monocyte adhesion and thus promote their recruitment. It has been shown that the relative content of extracellular fibrinogen increases during lesion development, and this study investigated the contribution of immobilized fibrinogen to monocyte adhesion and the underlying mechanism. Freshly isolated human blood monocytes were cultivated in serum-free RPMI 1640 in tissue culture wells precoated with albumin, fibrinogen, or fibrin. After 16 h the plates were washed and adherent cells enumcrated. Immobilized fibrinogen enhanced monocyte adhesion more than 1.9-fold compared to immobilized albumin or fibrin (P<0.05). Concomitant addition of the protein kinase C (PKC) inhibitors staurosporine or H7 suppressed monocyte adherence to immobilized fibrinogen but exerted no significant effect upon adhesion to any other surface tested. Stimulation of monocytes using phorbol myristate acetate resulted in increased binding of monocytes on fibrinogen but not on bovine serum albumin. When PKC activity was reduced through prolonged incubation with PMA for 16h, a significant reduction of monocyte adhesion on fibrinogen was observed. Peptides containing RGD sequences, which have been demonstrated to be ligands for certain integrins, did not inhibit monocyte adhesion. The data suggest that fibrinogen promotes monocyte adhesion in vitro by a PKC-dependent mechanism. PKC appears to be important not only for the initial cell adhesion but also for sustained binding of monocytes to fibrinogen.Abbreviations BSA Bovine serum albumin - ECM Extracellular matrix - PKC Protein kinase C - PMA Phorbol myristate acetate  相似文献   
146.
147.
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   
148.
Anosognosia and anosodiaphoria are terms that have frequently been used to cover a wide variety of different concepts. A review of the literature provides the point of departure for presentation of the methodological problems arising from the use of these terms. We then discuss the concept of anosognosia as a linguistic behavioural pattern arising from the patient's reaction to the "non-accessibility" of a cerebral lesion. Anosognosia can thus be interpreted as behaviourally analogous to neglect. Anosodiaphoria is presented as a form of behaviour determined by the patient's attempt to come to terms with the consequences that a cerebral lesion has for his way of life.  相似文献   
149.
From January, 1975 through June, 1986, 426 patients with mammary carcinomas were submitted to primary, breast-preserving therapy at the Gynecological Hospital of the University of Heidelberg. 212 women with a minimum observation time of twelve months fulfilled the criteria of a "typical" treatment: tumor size up to 3 cm, segment/quadrant resection and axillary lymphonodectomy with at least eight lymph nodes removed, radiotherapy of the residual breast with greater than or equal to 45 Gy, in case of histological lymph node manifestation adjuvant hormonal and/or chemotherapy. The average observation time was 38 months, the medium age 48 years. Patients with histological lymph node manifestations were compared with a matched control group of women treated treated by modified radical therapy. According to the error estimation of Kaplan and Meier (1958), no differences were found for local recurrence rate, disease-free survival, and overall survival. Patients treated by organ-preserving therapy with adjuvant chemotherapy were opposed to a matched control group of women treated only by surgical/radiological, organ-preserving therapy. In patients with chemotherapy, the incidence of cutaneous erythema (29% versus 24%), telangiectasia (34% versus 24%), hyperpigmentation (41% versus 34%) showed an upward tendency, but was not significantly increased. There was no difference in the incidence of clinically palpable fibroses (37% versus 42%) and fibroses shown by mammography (54% versus 51%). The frequency of pneumonitis/fibrosis of the retromammary lung area (22% versus 10%) after chemotherapy was two times higher than in the matched control group not treated by chemotherapy.  相似文献   
150.
The distribution and time course of gamma-aminobutyric acid (GABA) immunoreactivity was investigated in the cranium of the chick embryo from 2 to 16 days of incubation (E2-16). A fraction of nerve fibers transiently stains GABA-positive in all cranial motor nerves and in the vestibular nerve. Cranial motor nerves stain GABA-positive from E4 to E11, including neuromuscular junctions at E8-11; labeled fibers are most frequent in the motor trigeminal root (E6-9.5). Substantial GABA staining is present from E4 to E10 in a subpopulation (1-2%) of vestibular ganglion cells. Their peripheral processes are labeled in the vestibular endorgan, predominantly in the posterior crista. Some GABA-positive fibers are present in the olfactory nerve (after E5) and in the optic nerve (after E9.5); their immunoreactivity persists throughout the period investigated. Transient GABA immunoreactivity follows "pioneer" fiber outgrowth and coincides with the formation of early synaptic contacts. GABA-containing neurons may change their neuronal phenotype (loss of GABA expression) or they may be eliminated by embryological cell death. Periods of cell death were determined in cranial ganglia and motor nuclei by aggregations of pycnotic cells in the same embryonic material. The periods of embryonic cell death partly coincide with transient GABA immunoreactivity. The function(s) of transient GABA expression is unknown. Some lines of evidence suggest that GABA has neurotrophic functions in developing cranial nerves or their target tissue. In the developing neuromuscular junction, GABA may be involved in the regulation of acetylcholine receptors.  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