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   8046篇
  免费   494篇
  国内免费   31篇
耳鼻咽喉   94篇
儿科学   238篇
妇产科学   276篇
基础医学   1313篇
口腔科学   236篇
临床医学   789篇
内科学   1742篇
皮肤病学   196篇
神经病学   714篇
特种医学   176篇
外科学   769篇
综合类   52篇
一般理论   5篇
预防医学   712篇
眼科学   105篇
药学   525篇
中国医学   14篇
肿瘤学   615篇
  2024年   7篇
  2023年   65篇
  2022年   156篇
  2021年   300篇
  2020年   172篇
  2019年   245篇
  2018年   270篇
  2017年   215篇
  2016年   240篇
  2015年   249篇
  2014年   301篇
  2013年   429篇
  2012年   678篇
  2011年   628篇
  2010年   358篇
  2009年   306篇
  2008年   546篇
  2007年   565篇
  2006年   495篇
  2005年   543篇
  2004年   415篇
  2003年   384篇
  2002年   338篇
  2001年   50篇
  2000年   43篇
  1999年   58篇
  1998年   54篇
  1997年   44篇
  1996年   49篇
  1995年   42篇
  1994年   33篇
  1993年   39篇
  1992年   25篇
  1991年   28篇
  1990年   19篇
  1989年   15篇
  1988年   13篇
  1987年   15篇
  1986年   13篇
  1985年   19篇
  1984年   14篇
  1983年   17篇
  1982年   8篇
  1980年   13篇
  1979年   4篇
  1978年   4篇
  1973年   4篇
  1972年   5篇
  1971年   5篇
  1970年   5篇
排序方式: 共有8571条查询结果,搜索用时 15 毫秒
21.
Fourteen consecutive patients with burst fractures at T12 or L1, partial paralysis, and more than 30% canal compromise were prospectively evaluated pretreatment and posttreatment with roentgenograms to determine the initial fracture pattern, CT scans to determine the percent canal compromise and subsequent improvement, and a quantitative motor trauma index scale and bladder sphincter evaluation to determine neurologic recovery. The follow-up period averaged 32 months (range, 12-50 months). Treatment was as follows: nonoperative (three patients), Harrington rods and fusion (seven patients), and Harrington rods and fusion followed by anterior decompression and fusion (four patients). The initial severity of paralysis did not correlate with the initial fracture roentgenographic pattern or the amount of initial CT canal compromise. Neurologic recovery did not correlate with the treatment method or amount of canal decompression. Subsequent recovery did correlate with the initial fracture pattern. If the patient had a Type I or Type II fracture (both greater than 15 degrees kyphosis), greater than 90% neurologic recovery occurred, regardless of treatment. If the patient had a Type III fracture (less than 15 degrees kyphosis and the maximal canal compromise where bone encircles the canal) less than 50% neurologic recovery occurred. If the patient had a Type IV fracture (less than or equal to 15 degrees kyphosis and the maximal canal compromise at the level of the ligamentum flavum), the neurologic recovery was variable. Prognosis for neurologic recovery can be made based on initial roentgenograms. If greater than 15 degrees kyphosis is present, there is a good prognosis.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
22.
International conference calendar  相似文献   
23.
Accelerated polymerization of acrylic bone cement using preheated implants   总被引:1,自引:0,他引:1  
This article is an account of a procedure to accelerate polymerization of polymethylmethacrylate during total hip arthroplasty by preheating the stem of the femoral prosthesis. The increased temperature is shown to have a definite beneficial effect with regard to accelerated polymerization. Experimental investigations are presented to verify this supposition.  相似文献   
24.
BACKGROUND: Thiazolidinediones (TZD) have been reported to improve early stages of diabetic nephropathy independent of glycaemic control. Since blockade of the renin-angiotensin system (RAS) is known to reduce the risk of nephropathy, we hypothesised that the renal effect of TZDs might be related to a favourable effect on the intrarenal RAS. We aimed to determine if the TZD rosiglitazone could reduce RAS activation. METHODS: We studied adult type 2 diabetic patients and placed them on rosiglitazone for three months. We have previously used the renal haemodynamic response to angiotensin-converting enzyme (ACE) inhibition to demonstrate the state of RAS activation, and thus measured renal plasma flow (RPF) and glomerular filtration rate (GFR) before and after administration of captopril at 0 month and at three months. Plasma renin activity (PRA), active renin, aldosterone and natriuretic peptides were analysed. RESULTS: The RPF response to ACE inhibition was not altered. There was no change in GFR, PRA, active renin and aldosterone levels. Two patients developed oedema one had an elevated baseline active renin and another had an elevated baseline aldosterone level. CONCLUSION: The favourable effects of TZDs on diabetic nephropathy is likely not related to an influence on the RAS.  相似文献   
25.
Summary The Lifetime and 6 month DSM-III prevalence rates of mental disorders from an adult general population sample of former West Germany are reported. The most frequent mental disorders (lifetime) from the Munich Follow-up Study were anxiety disorders (13.87%), followed by substance (13.51%) and affective (12.90%) disorders. Within anxiety disorders, simple and social phobia (8.01%) were the most common, followed by agoraphobia (5.47%) and panic disorder (2.39%). Females had about twice the rates of males for affective (18.68% versus 6.42%), anxiety (18.13% versus 9.07%), and somatization disorders (1.60% versus 0.00%); males had about three times the rates of substance disorders (21.23% versus 6.11%) of females. Being widowed and separated/divorced was associated with high rates of major depression. Most disordered subjects had at least two diagnoses (69%). The most frequent comorbidity pattern was anxietyand affective disorders. Simple and social phobia began mostly in childhood or early adolescence, whereas agoraphobia and panic disorder had a later average age of onset. The majority of the cases with both anxiety and depression had depression clearly after the occurrence of anxiety. The DIS-DSM-III findings of our study have been compared with both ICD-9 diagnoses assigned by clinicians independently as well as other epidemiological studies conducted with a comparable methodology.  相似文献   
26.
27.
OBJECTIVE: The efficacy of a low-protein diet in the secondary prevention of diabetic nephropathy is not established in patients with type 1 or type 2 diabetes mellitus. To determine whether a low-protein diet slows the decrease in glomerular filtration rate (GFR) and decreases the albumin excretion rate (AER) in diabetic patients with incipient and overt nephropathy, we performed a 2-year prospective, randomized controlled trial comparing the effects of a low-protein diet (0.8 g/kg/day) with a usual-protein diet. SETTING AND PATIENTS: The study was conducted in a University hospital and included 63 type 1 and type 2 diabetic patients with either incipient or overt nephropathy and mild renal failure (prestudy GFR, 80 +/- 20 mL/min). The primary outcome measures were decreased in GFR and 24-hour AER. RESULTS: In the low-protein-diet group, patients were younger (52 +/- 12 versus 63 +/- 9 years old) and more often were type 2 diabetic. During the follow-up period, according to dietary records the low-protein-diet group consumed 16% +/- 3% of total caloric intakes as compared with 19% +/- 4% in the usual-protein-diet group (P < .02), but 24-hour urinary urea excretions did not differ between the two groups. The 2-year GFR decrease was 7 +/- 11 mL/min in the low-protein-diet group and 5 +/- 15 mL/min in the usual-protein-diet group (P = not significant). AER did not increase significantly in the two diet groups during the follow-up period. Blood pressure and glycemic control were similar in the two groups all along the study. The decrease in GFR and AER were also similar in 6 compliant patients according to dietary records and to 24-hour urinary urea excretions from the low-protein-diet group and in 12 patients from the usual-protein-diet group. CONCLUSIONS: A 2-year low-protein diet did not alter the course of GFR or of AER in diabetic patients with incipient or overt nephropathy receiving renin-angiotensin blockers with strict blood pressure control.  相似文献   
28.
29.
Nosocomial pressure ulcers (PU) occur in approximately 12% of all hospitalized patients. The risk can be determined by a variety of intrinsic and extrinsic factors. As a first line of defense against nosocomial PU, we use the Braden Scale to determine the potential risk of PU development during hospitalization. Once risk was identified, our standard was to implement an individualized plan of care. However, consistent implementation of PU preventative measures was lacking. As a result, a process improvement project was developed and implemented. The purpose of this process improvement project was to increase communication about and awareness of the need to vigorously intervene and document whenever there is risk of, or development of, a nosocomial PU. By initiating consistent use of a PU Tracking Form, developing unit-based wound champions that serve as experts in ulcer prevention, and creating an individual case analysis process, PU prevention and tracking was institutionalized. Results indicate that our nosocomial PU rate has declined from 7% to 4%.  相似文献   
30.
P. Dall  O. G. Wilhelm 《Der Gyn?kologe》1998,31(12):1075-1082
Zum Thema Zell- und molekularbiologische Methoden haben es in den letzten 25 Jahren erm?glicht, Erkenntnisse in intra- und interzellul?re Funktionsabl?ufe und deren St?rungen zu gewinnen. Besonders in der Onkologie kam es zu einem zunehmenden Wissen über dysregulierte Gene, sog. Onkogene, welche ein dysfunktionelles (Onko)Protein produzieren und damit Zellwachstum und Proliferation in Richtung Malignit?t beeinflussen k?nnen. Tumorsuppressorgene (TSG) wirken regulierend auf den Zellzyklus ein, und im Falle einer vererbten Mutation des einen Allels und einer Deletion des intakten Allels durch Funktionsverlust k?nnen Malignome induziert bzw. Malignomentstehung begünstigt werden. Ein Beispiel hierfür ist das Li-Fraumeni-Syndrom, bei welchem es aufgrund einer Mutation des Tumorsuppressorgens p53 zu einer geh?uften Inzidenz von Mamma- und Ovarialkarzinomen kommt. ?nderungen von Proteasen- oder Adh?sionsmolekülfunktionen von Zellen spielen eine wichtige Rolle bei der Tumorzellinvasion und Metastasierung. Blockierung von Proteasesystemen, z. B. Urokinase/Plasmin-System oder Matrixmetalloproteasen, führen zu einer Inhibierung von Tumorzellinvasion und Metastasierung in vitro und in vivo. Bei einigen Malignomen kommt es zu einer Vermehrung von Genkopien, einer sog. Genamplifikation, wie sie z. B. für Rezeptoren der epidermal „Growth-factor-Familie“ (EGF-R, erbB2, erbB3, erbB4) beschrieben sind. Die betroffenen Zellen reagieren dadurch vermehrt auf autokrine und parakrine Signale und hyperproliferieren. Die Gentherapie stellt durch Wiederherstellung physiologischer Funktionsabl?ufe einen vielversprechenden Ansatz zur Behandlung maligner Erkrankungen dar. Der vorliegende übersichtsartikel wird ohne Anspruch auf Vollst?ndigkeit nach einer kurzen Einführung in die Grundlagenaspekte der Gentherapie und deren derzeitigen Probleme pr?klinische und erste klinische Ergebnisse darstellen.  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