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   59465篇
  免费   3473篇
  国内免费   48篇
耳鼻咽喉   891篇
儿科学   1812篇
妇产科学   1423篇
基础医学   8950篇
口腔科学   2170篇
临床医学   5520篇
内科学   10628篇
皮肤病学   1480篇
神经病学   6496篇
特种医学   2748篇
外科学   8309篇
综合类   202篇
一般理论   32篇
预防医学   3818篇
眼科学   1256篇
药学   4035篇
中国医学   97篇
肿瘤学   3119篇
  2023年   328篇
  2022年   235篇
  2021年   515篇
  2020年   581篇
  2019年   627篇
  2018年   1325篇
  2017年   1131篇
  2016年   1469篇
  2015年   1184篇
  2014年   1359篇
  2013年   2509篇
  2012年   3165篇
  2011年   3591篇
  2010年   1890篇
  2009年   1208篇
  2008年   3569篇
  2007年   3734篇
  2006年   3524篇
  2005年   3413篇
  2004年   3282篇
  2003年   3323篇
  2002年   3253篇
  2001年   2537篇
  2000年   3263篇
  1999年   1714篇
  1998年   566篇
  1997年   484篇
  1996年   356篇
  1995年   296篇
  1994年   317篇
  1993年   304篇
  1992年   277篇
  1991年   223篇
  1990年   210篇
  1989年   278篇
  1988年   210篇
  1987年   210篇
  1986年   219篇
  1985年   271篇
  1984年   311篇
  1983年   261篇
  1982年   256篇
  1981年   214篇
  1980年   207篇
  1979年   234篇
  1978年   175篇
  1977年   192篇
  1976年   187篇
  1975年   165篇
  1973年   175篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
Schlu?folgerungen Unser Motto in der Chirurgie sollte hei?en: „An erster Stelle steht die Qualit?t, erst sekund?r kommen die Kosten.“ In diesem Sinne verstehen wir auch die vorgelegte Arbeit vonKriwanek et al. (1). Durch den Gebrauch von wiederverwendbaren Instrumenten (oder Kombinationen davon) konnten die Kosten der LC um 50 bis 70% reduziert werden. Die Qualit?t für den Chirurgen litt jedoch unter dem reinen Gebrauch von wiederverwendbaren Instrumenten. Deshalb erachten es die Autoren für sinnvoll, eine Kombination zwischen Wegwerfinstrumenten und wiederverwendbaren Instrumenten anzuwenden. Damit entsteht unter leichter Erh?hung der Kosten keine Qualit?tseinbu?e und demzufolge ein maximaler Nutzen für die Patienten (nicht jedoch für die Spital?konomen). Jede Kosten-Nutzen-Analyse unterliegt jedoch einem stetigen Flu? und ver?ndert sich demzufolge auch mit der Einführung neuer Produkte und Technologien von Seite der Industrie. Interessant für die gesamte Laparoskopie wird es jedoch dann, wenn solche Kosten-Nutzen-Analysen auf andere Gebiete wie z. B. die Therapie der Leistenhernie oder der Gallengangssteine übertragen werden. Diese Ergebnisse werden die weitere Zukunft der laparoskopischen Chirurgie wesentlich beeinflussen. Deshalb gilt es für uns Chirurgen, eine Sensibilit?t für ?konomische Aspekte zu entwickeln und Kosten-Nutzen-Analysen für das eigene Spital (wie hier gezeigt) zu erarbeiten.  相似文献   
92.
Objective: To quantify gadolinium-related enhancement in the bone marrow of the spine in normals and in patients with homogeneous diffuse malignant bone marrow infiltration. Design and patients: The patients consisted of two groups: group 1 comprised 94 healthy adults (18–86 years) without bone marrow disease and group 2 comprised 30 patients with homogeneous diffuse malignant bone marrow infiltration due to myeloma (n=20) or breast carcinoma (n=10). All patients received intravenous gadopentetate dimeglumine (Gd-DTPA), 0.1 mmol/kg body weight. Pre- and postcontrast signal intensity (SI) on T1-weighted spin-echo (SE) images (TR/TE: 572 ms/15 ms) was measured over a region of interest (ROI) and the percentage SI increase was calculated. The results were confirmed by bone marrow biopsy (n=20) and clinical parameters (n=10). Dynamic contrast-enhanced studies using a spoiled gradient-recalled-echo (GRE) sequence (TR/TE/α: 68 ms/6 ms 75°) were performed in 10 controls with normal bone marrow. Results and conclusion: Contrast material enhancement in healthy persons can vary greatly (range 3–59%, mean 21%, SD 11%). With increasing age there is a significant decrease in contrast enhancement (Pearson’s correlation, P<0.01). The percentage SI increase in patients with intermediate-grade (biopsy 20–50 vol%) and high-grade (biopsy >50 vol%) diffuse malignant bone marrow infiltration was significantly higher than in normals (mean 67%, SD 34%, P<0.001). Low-grade (biopsy <20 vol%) diffuse malignant bone marrow infiltration can not be assessed by non-enhanced T1-weighted SE images or Gd-DTPA application. In conclusion, contrast material enhancement in healthy persons can vary greatly and is dependent on age, while intermediate-grade and high-grade diffuse malignant bone marrow infiltration can be objectively assessed with SI measurements.  相似文献   
93.
94.
According to Sperry's chemoaffinity hypothesis, the projection of a small eye fragment with a reduced amount of optic fibres should be restricted to that position in the optic tectum corresponding to its own specificity. However, previous investigations on different types of quarter-eyes in Xenopus laevis have revealed that their retinal projection was always restricted to the rostral part of the tectum, no matter what the origin of the remaining retinal quadrant. To get an indication of the state of specificity in such eye fragments, we investigated by electrophysiological and histological methods several features of the retinal projections of temporoventral (TV), naso-ventral (NV) and ventral (V) quarter-eyes which referred to their positional identity. Irrespective of their different origins, the projections were always located in the rostral part of the tectum, the size of the innervated tectal area depending for all fragment types on the size of the quarter-eyes, i.e. number of optic fibres. However, quantitative analyses revealed that with increasing eye size the various fragments expand their projections preferentially into those tectal areas that match their original specificity: TV projection is more concentrated in the rostral tectum, NV eyes expand their projections mainly to the caudal tectum, and V eyes enlarge their projections equally into the medial and caudal tectum. In addition, fibre-tracing experiments with cobaltic lysine showed that, according to the different origins of the quarter-eyes, retinal fibres follow the appropriate branch of the optic tract selectively: fibres of NV and V eyes pass mainly through the medial tract, and most fibres of TV eyes innervate the rostral tectum directly from a central position between the two side branches. All these findings suggest that the different types of quarter-eyes retain their original positional identity. Thus, their rostrally located retinotectal projections are not in register with their retinal specificity. We conclude that in X. laevis local positional markers in the tectum, if present at all, do not influence the development of the retinotectal projection. Instead we suggest a concept of self-sorting of the optic fibres, which can account for the partial innervation of the rostral tectum in different types of quarter-eyes.  相似文献   
95.
96.
In a group of 69 patients with pituitary tumours, 12 were found to have evidence of intratumoral haemorrhage on MRI, characterized by high signal intensity on short TR/TE sequences. This was verified in all but 1 patient. The majority of the bleedings occurred in macroadenomas. Five (42%) were prolactinomas and 4 (33%) were non-functioning adenomas. There were 2 GH- and 1 ACTH-secreting tumours. All 5 patients with prolactinomas were on bromocriptine medication. Two of the patients had a clinical picture of pituitary apoplexy. The haemorrhage was not large enough to prompt surgery in any of the patients. However, surgical verification of the diagnosis was obtained in 5 cases, while 6 patients were examined with follow-up MRI.  相似文献   
97.
Between November 1984 and January 1994 in our department, a total of 2500 patients were treated with totally absorbable internal fixation devices. We studied these patients and analyzed results with regard to the volume of the absorbable implants and the development of wound infection. Of the 2500 patients 2044 were trauma patients and 456 were operated on for orthopedic disease. In 1466 patients treated with implants made of self-reinforced polyglycolic acid (SR-PGA) only, the patients who developed wound infection had a higher implant volume (P=0.07) than those who did not; this difference was close to statistical significance. In the 446 patients who received only implants made of self-reinforced poly-l-lactic acid (SR-PLLA), the 5 who developed wound infection had a mean implant volume more than three times that of the non-infected patients (P=0.01). We found that in the patients treated with the earlier SR-PGA implants, which contained a green staining material, there was no correlation between implant volume and incidence of wound infections. On the other hand, both the non-stained SR-PGA implants, which have been in clinical use since 1989, and the SR-PLLA implants, seem to be more predictable in terms of wound infections. We believe that this difference, is largely due to the lower level of tissue reactions with these newer implants.  相似文献   
98.
Patients treated for sporadic and hereditary medullary thyroid carcinoma (MTC) have varying rates of persistent disease, recurrence, and survival. The aim of this study was to correlate the immunoreactivity of the monoclonal antibody CD15 (LeuM1) to initial clinical findings and the outcome of treatment. The primary tumors of 75 patients with sporadic MTC, 7 with hereditary disease, and 3 members of MEN 2A families were studied. Of these subjects 74 (87%) showed no or little immunoreactivity (<15% positive cells; score 0) in most tumors. The remaining 13% had surgery for tumors with more than 15% cells with positive staining (score I). There was no correlation between LeuM1 immunoreactivity and sex, age, and type of MTC. There was, however, a significant correlation with the pTNM classification and UICC staging. The prognosis for patients with score 0 was significantly better than score 1 patients. CD15 immunoreactivity appears to be a predictive factor in sporadic and hereditary MTC. Lymph node dissection seems to be more successful in patients with score 0 tumors than in those with score 1 tumors. The question of reoperation in patients with recurrence of disease (especially with biochemical recurrence or persistence) should be discussed on the basis of CD15 immunoreactivity.
Resumen Los pacientes tratados para carcinoma medular, esporádico y hereditario, de la glándula tiroides (CMT) exhiben grandes variaciones en las tasas de enfermedad persistente, recidiva y sobrevida. El propósito del presente estudio fue establecer la correlación entre la inmunorreactividad del anticuerpo CD15 (LeuM1) y los hallazgos clínicos iniciales, así como con el resultado final del tratamiento.Se estudiaron los tumores primarios de 75 pacientes con CMT esporádico, de siete con enfermedad hereditaria y de 3 miembros de familias con síndrome NEM2A.Setenta y cuatro pacientes (87%) exhibieron ninguna o muy baja inmunorreactividad (menos de 15% de células positivas; puntaje 0) en la mayoría de los tumores. El 13% restante fue sometido a cirugía por tumores con más de 15% de las células con coloración positiva (puntaje 1). No se evidenció correlación entre la inmunorreactividad LeuM1 y el sexo, edad o tipo del CMT. Sin embargo, sí apareció una correlación significativa con la clasificiación pTNM y la estadificación de la UICC. El pronóstico de los pacientes con puntaje 0 resultó significativamento mejor que el de los pacientes con puntaje 1.La inmunorreactividad CD15 parece ser un factor de predicción de pronóstico en el CMT esporádico y familiar. La disección ganglionar parece ser más exitosa en pacientes con tumores de puntaje 0 que en los que portan tumores con puntaje 1.El interrogante en cuanto a reoperación en pacientes con recidiva de la enfermedad (especialmente cuando hay recidiva o persistencia bioquímica) debe ser considerada con base en la inmunorreactividad CD15.

Résumé Les taux de maladie persistante, de récidive et de survie chez des patients traités pour cancer médullaire sporadique et héréditaire de la thyroïde (CMT) sont très variables. Le but de cette étude a été de corréler l'immunoréactivité des anticorps monoclonaux CD15 (LeuM1) à des données cliniques initiales et l'évolution finale du traitement des CMT. On a étudié 75 patients ayant un CMT primitif, sept ayant une maladie héréditaire, et trois membres d'une famille MEN 2A. Soixante quatre patients (87%) avaient peu ou pas d'immunoréactivité (moins de 15% de cellules positive: score = 0). Les 13% restants ont eu une chirurgie pour les tumeurs ayant un pourcentage > 15 (score = 1). Il n'y avait aucune corrélation entre l'immunoréactivité LeuM1 et le sexe, l'âge et le type de CMT. Il y avait, en revanche, une corrélation significative entre la classification pTMN et le stage UICC. Le pronostic des patients ayant un score = 0 était significativement meilleur que celui des patients ayant un score = 1. L'immunoréactivité CD15 apparaît comme étant un facteur pronostique des CMT. Le curage lymphatique


Members and institutions are listed in Table 1.  相似文献   
99.
In this retrospective study of 24 patients who were treated at our clinic during the last 22 years after having attempted suicide, we evaluated aspects concerning abdominal-and transplantation surgery. There was a predominance of “hard” (70%) versus “soft” (30%) methods for suicide attempt. Intra-abdominal injuries resulting from attempted suicide by stabbing or shooting should lead to laparotomy— the prognosis is then good. Surgical treatment after intoxication, especially caustic ingestion, depends on endoscopic and clinical findings. The highly increased rates of suicide significantly by kidney transplantation. The risk of suicide after transplantation is further diminished with improved immunosuppressive treatment. Only in a few cases there is an indication for liver transplantation— in some cases of fulminant hepatic failure caused by self-administered paracetomol overdose. Auxiliary liver transplantation may then be considered.  相似文献   
100.
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