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   1952篇
  免费   158篇
  国内免费   54篇
耳鼻咽喉   13篇
儿科学   29篇
妇产科学   94篇
基础医学   206篇
口腔科学   41篇
临床医学   227篇
内科学   427篇
皮肤病学   55篇
神经病学   88篇
特种医学   136篇
外科学   260篇
综合类   35篇
一般理论   3篇
预防医学   239篇
眼科学   14篇
药学   193篇
肿瘤学   104篇
  2021年   33篇
  2020年   21篇
  2019年   25篇
  2018年   51篇
  2017年   26篇
  2016年   33篇
  2015年   40篇
  2014年   47篇
  2013年   66篇
  2012年   89篇
  2011年   85篇
  2010年   52篇
  2009年   36篇
  2008年   75篇
  2007年   135篇
  2006年   96篇
  2005年   97篇
  2004年   81篇
  2003年   54篇
  2002年   83篇
  2001年   86篇
  2000年   87篇
  1999年   49篇
  1998年   38篇
  1997年   24篇
  1996年   39篇
  1995年   25篇
  1994年   35篇
  1993年   15篇
  1992年   32篇
  1991年   30篇
  1990年   44篇
  1989年   41篇
  1988年   45篇
  1987年   25篇
  1986年   26篇
  1985年   27篇
  1984年   16篇
  1983年   13篇
  1981年   13篇
  1980年   11篇
  1979年   12篇
  1978年   14篇
  1977年   11篇
  1976年   16篇
  1975年   15篇
  1974年   9篇
  1973年   14篇
  1967年   11篇
  1966年   10篇
排序方式: 共有2164条查询结果,搜索用时 109 毫秒
1.
2.
This study represents the first of a two-stage project. The first phase of the study examined the funding sources for the 40 Community Services Boards in Virginia. Data provided from the Department of Mental Health and Mental Retardation in Virginia examined fee collections which are comprised of direct client, commercial insurance, Medicaid and Medicare. An analysis of quarterly reports from 1982 to 1984 revealed that Medicaid collections have decreased significantly, while commercial insurance reimbursements have increased significantly. These results, although limited to data from Virginia, point to the need to examine if these shifts are occurring nation-wide, and to determine if the shift toward commercial insurance is impacting upon the delivery of services in Community Mental Health Centers.  相似文献   
3.
Open, Double-Blind and Long-Term Study of Vigabatrin in Chronic Epilepsy   总被引:5,自引:4,他引:1  
We performed an open, double-blind, and long-term study of vigabatrin (gamma-vinyl-GABA, GVG) in patients with treatment-resistant epilepsy who were receiving only one or at most two standard antiepileptic drugs (AEDs). The novel design included a parallel, double-blind, placebo-controlled phase that minimized the number of patients receiving placebo and allowed determination of the optimum dose of GVG for each patient before initiation of the double-blind phase. The study was divided into four phases. The first phase was a 6-week period of baseline observation. In the second phase, GVG was added openly to previous AEDs for 8 weeks. During the first 2 weeks of this phase, the dose of GVG was increased weekly and then, in the absence of adverse effects, was held constant for the next 6 weeks. At the end of this open phase, seizure frequency during the 6 weeks of constant treatment was compared with the baseline seizure frequency for each patient. Patients who experienced reduction greater than 50% in the frequency of any seizure type during the open phase were defined as responders. These responders were then entered into the third and double-blind phase, in which they were randomly allocated wither to continue active GVG treatment or placebo for 8 weeks. Thirty-three patients entered the study; 31 of 33 patients completed the initial open phase. Twenty patients achieved a reduction greater than or equal to 50% in the frequency of one or more seizure types and were eligible for the double-blind phase; 10 were randomized to continue GVG and 10 were randomized to placebo.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
4.
5.
6.
In order to assess what different health care workers (mainly physicians and nursing staff) know about the reporting of communicable diseases, with special emphasis on diseases that must be urgently reported, four groups were interviewed about this health information system (91 persons, who took part in different Public Health Seminars during the periods 1989-90 and 1990-91). The total mean score was 16.6 +/- 5.2, in a quantitative scale ranging from 0 to 27 points. Cholera was the communicable disease with the highest percentage of correct answers concerning the knowledge of its reporting (100% in two groups), while typhus was the disease with the lowest percentage (23%). The diversity of the results within the study groups suggests that it is necessary to insist on a continuous training on epidemiological surveillance and communicable diseases within Public Health activities in Catalonia.  相似文献   
7.
The clinical performance of the Copper T380A (TCu380A) and the Multiload 250 (MLCu250) intrauterine devices (IUDs) were evaluated for 12 months in a group of women who had one of the two IUDs inserted. Results are from a randomized clinical trial conducted at four collaborating research sites located in three developing countries.The gross cumulative life-table pregnancy rate of the TCu380A IUD was significantly lower than the rate with the MLCu250 IUD at 12 months (0.5 and 1.2, respectively,p<0.01). No statistically significant differences between the two study IUDs were found with regard to IUD expulsion or IUD removal due to bleeding/pain, personal reasons, medical reasons, or planned pregnancy. TCu380A IUD users were more likely to report experiencing increased dysmenorrhea (p<0.01) or intermenstrual pelvic pain (p<0.01) than were MLCu250 IUD users. However, few of these users discontinued use of their assigned IUD because of having experienced menstrual bleeding disturbances or intermenstrual pelvic pain.These data indicate that the TCu380A IUD may be a better option than the MLCu250 IUD for women wishing to practice highly effective long-term birth control without having to resort to hormonal methods.
Resumen El resultado clínico de los dispositivos intrauterinos (DIU) Copper T380A y Multiload 250 (MLCu250) se evaluó durante 12 meses en un grupo de mujeres a quienes se había colocado uno de los dos DIU. Los resultados corresponden a un ensayo clínico aleatorizado efectuado en cuatro emplazamientos de investigaciones en colaboración situados en tres países en desarrollo.La tasa bruta acumulativa de embarazo de las tablas de vida del DIU TCu380A fue significativamente inferior a la tasa correspondiente al DIU MLCu250 a los 12 meses (0,5 y 1,2, respectivamente,p<0,01)). No hubo diferencias estadísticamente significativas entre los dos DIU del estudio con respecto a su expulsión o retiro debido a microrragia/dolor, razones personales, razones médicas o embarazo planificado. Era más probable que las usuarias del DIU TCu380A notificaran mayor dismenorrea (p<0,01) o dolor pélvico intermenstrual (p<0,01) que las usuarias del DIU MLCu250. Sin embargo, un número menor de este grupo de usuarias dejó de utilizar el DIU que le había sido asignado por haber experimentado trastornos menstruales de microrragia o dolor pélvico intermenstrual.Estos datos indican que el DIU TCu380A podría ser una mejor opción que el DIU MLCu250 para las mujeres que desean praticar un control de la natalidad a largo plaza altamente eficaz sin tener que recurrir a métodos hormonales.

Resumé Les résultats cliniques des dispositifs intra-utériens (DIU) Copper T38OA (TCu380A) et Multiload 250 (MLCu250) ont été évalués pendant 12 mois chez un groupe de femmes qui portaient l'un ou l'autre de ces dispositifs. Les résultats proviennent d'un essai clinique randomisé, effectué en collaboration par quatre établissements de recherche dans trois pays en développement.Au terme de 12 mois, le taux brut cumulé de grossesses des tables de survie pour le dispositif TCu380A était significativement inférieur au taux correspondant pour le dispositif MLCu250 (0,5 et 1,2 respectivement,p<0,01). Aucune différence statistiquement significative entre les deux dispositifs étudiés n'a été constatée du point de vue de l'expulsion du DIU ou de son retrait pour cause de microrragie/douleurs, pour des raisons personnelles ou médicales ou pour une grossesse planifiée. Les utilisatrices du TCu380A ont plus fréquemment signalé une dysménorrhée (p<0,01) ou des douleurs pelviennes intermenstruelles (p<0,01) que les utilisatrices du MLCu250. Peu nombreuses était cependant cells qui avaient, en raison de perturbations du flux menstruel ou de douleurs pelviennes intermenstruelles, abandonné l'usage du dispositif qui leur avait été assigné.Ces résultats indiquent que le dispositif TCu380A représente peut-être une meilleure solution que le dispositif MLCu250 pour les femmes recherchant à long terme une méthode hautement efficace de régulation des naissances, sans avoir recours aux méthodes hormonales.
  相似文献   
8.
9.
Nodular regenerative hyperplasia of the liver is an uncommon cause of portal hypertension. Patients with nodular regenerative hyperplasia have signs and symptoms of portal hypertension, without evidence of hepatocellular failure or encephalopathy. We report the case of a 44-year-old woman with recurrent esophageal bleeding and refractory ascites who had a history of hemosiderosis, hepatitis C, and chronic renal allograft rejection. Our preoperative diagnosis was cirrhotic end-stage liver disease and end-stage renal disease for which the patient underwent combined hepatic and renal transplantation. Her portal hypertension symptoms resolved, and her renal function has been normal for 18 months of follow-up. Histologic examination of the liver revealed nodular regenerative hyperplasia, and a review of the literature regarding the surgical management of patients with nodular regenerative hyperplasia revealed that various shunting procedures are generally recommended. After the failure of medical management in patients with nodular regenerative hyperplasia, portosystemic shunting may be indicated before proceeding to hepatic transplantation.  相似文献   
10.
BACKGROUND. The incidence of infection increases with the prolonged use of central vascular catheters, but it is unclear whether changing catheters every three days, as some recommend, will reduce the rate of infection, It is also unclear whether it is safer to change a catheter over a guide wire or insert it at a new site. METHODS. We conducted a controlled trial in adult patients in intensive care units who required central venous or pulmonary-artery catheters for more than three days. Patients were assigned randomly to undergo one of four methods of catheter exchange: replacement every three days either by insertion at a new site (group 1) or by exchange over a guide wire (group 2), or replacement when clinically indicated either by insertion at a new site (group 3) or by exchange over a guide wire (group 4). RESULTS. Of the 160 patients, 5 percent had catheter-related bloodstream infections, 16 percent had catheters that became colonized, and 9 percent had major mechanical complications. The incidence rates (per 1000 days of catheter use) of bloodstream infection were 3 in group 1, 6 in group 2, 2 in group 3, and 3 in group 4; the incidence rates of mechanical complications were 14, 4, 8, and 3, respectively. Patients randomly assigned to guide-wire-assisted exchange were more likely to have bloodstream infection after the first three days of catheterization (6 percent vs. 0, P = 0.06). Insertions at new sites were associated with more mechanical complications (5 percent vs. 1 percent, P = 0.005). CONCLUSIONS. Routine replacement of central vascular catheters every three days does not prevent infection. Exchanging catheters with the use of a guide wire increases the risk of bloodstream infection, but replacement involving insertion of catheters at new sites increases the risk of mechanical complications.  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