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   15095篇
  免费   1209篇
  国内免费   49篇
耳鼻咽喉   110篇
儿科学   494篇
妇产科学   448篇
基础医学   1957篇
口腔科学   345篇
临床医学   1620篇
内科学   2970篇
皮肤病学   125篇
神经病学   1562篇
特种医学   520篇
外科学   2048篇
综合类   331篇
一般理论   26篇
预防医学   1604篇
眼科学   303篇
药学   982篇
中国医学   45篇
肿瘤学   863篇
  2022年   89篇
  2021年   172篇
  2020年   110篇
  2019年   168篇
  2018年   180篇
  2017年   144篇
  2016年   167篇
  2015年   232篇
  2014年   275篇
  2013年   520篇
  2012年   705篇
  2011年   813篇
  2010年   430篇
  2009年   400篇
  2008年   759篇
  2007年   827篇
  2006年   863篇
  2005年   857篇
  2004年   846篇
  2003年   810篇
  2002年   835篇
  2001年   233篇
  2000年   254篇
  1999年   291篇
  1998年   218篇
  1997年   192篇
  1996年   169篇
  1995年   175篇
  1994年   129篇
  1993年   152篇
  1992年   253篇
  1991年   207篇
  1990年   181篇
  1989年   193篇
  1988年   217篇
  1987年   187篇
  1986年   179篇
  1985年   183篇
  1984年   204篇
  1983年   146篇
  1982年   174篇
  1981年   171篇
  1980年   142篇
  1979年   145篇
  1978年   147篇
  1977年   118篇
  1976年   86篇
  1975年   110篇
  1974年   115篇
  1973年   102篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
1. Twenty-two patients hospitalized for treatment of depression were treated under conditions simulating those of home treatment. 2. Full doses of nortriptyline, from 100 to 150 mg/day, were started after baseline observations were made. 3. Two patients were dropped from the study, one for orthostatic hypotension, one for an aberrant response to nortriptyline. Two additional patients developed orthostasis which was easily managed. Otherwise no unusual side effects were noted. 4. After six days of treatment, 9 of 20 patients showed significant improvement with an overall reduction in scores on the Hamilton Depression Scale of 49% for the entire group. 5. Using the weight-adjusted dosage schedule, 18 of the 21 patients attained plasma concentrations of nortriptyline within the presumed therapeutic range; however, no clear relationship could be established between plasma concentrations and clinical response. 6. With proper selection of patients, it should be possible to treat at home some patients who currently are considered to require hospitalization.  相似文献   
2.
Cerebral dysgenesis encompasses varied disorders of brain development. Based on the understanding of these conditions provided by histopathologists, embryologists, radiologists and developmental pediatricians, surgeons are able to appropriately assist in the care of these patients. The surgeon can offer assessment of the ventriculomegaly that commonly accompanies cerebral dysgenesis in addition to providing methods to control hydrocephalus, to reconstruct cranial and facial malformations and to remove dysfunctional tissue. For most patients, surgical intervention is only one of the many factors that determine developmental prognosis. Based on the foundation built by other specialists, this review discusses cerebral dysgenesis from the perspective of historical and current surgical interventions.  相似文献   
3.
4.
Transport of 45Ca from the lumen to the venous effluent was studied in duodena of normal, vitamin D3-replete (+D) chicks perfused through the celiac artery with 130 pM 1,25(OH)2D3 or vehicle. Administration of actinomycin D 3 h prior to perfusion did not alter the unstimulated transport rate or diminish the response to exogenous 1,25(OH)2D3: After 40 min exposure to the seco-steroid, 45Ca in the vascular effluent was 140% of control levels. The anti-microfilament agent cytochalasin b and the ionophore monensin, an inhibitor of Golgi function, similarly failed to suppress 1,25(OH)2D3-stimulated calcium transport. In pilot studies, Golgi and basal-lateral membrane fractions were prepared from duodenal epithelium of vitamin D-deficient (-D) chicks treated with vehicle or 650 pmol of 1,25(OH)2D3 in vivo 2 h, 10 h, or 15 h before sacrifice, as well as from +D birds. Analyses of Golgi fractions for cathepsin B (CB) activity revealed a biphasic response with time, increasing to 200% of -D levels 2 h after 1,25(OH)2D3 administration and in equivalent preparations from +D birds. Less pronounced increases in acid phosphatase activity were observed in the same membrane fractions. In basal-lateral membranes, enhanced CB activity was detectable 10 h after 1,25(OH)2D3 in vivo, rose to 155% of -D levels at 15 h, and to 245% of controls in fractions from +D birds, whereas acid phosphatase was 75%, 81%, and 125% of controls, respectively, at these times.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
5.
This study examined the structure and symptom correlates of perfectionism in a sample of 6th-grade, urban, African American children using the Child and Adolescent Perfectionism Scale (CAPS; Flett, Hewitt, Boucher, Davidson, & Munro, 2000). Confirmatory factor analysis showed inadequate fit of the original subscales. Exploratory factor analysis suggested 3 dimensions of perfectionism: A Socially Prescribed and a Self-Oriented-Critical factor were described as maladaptive, whereas a Self-Oriented-Striving factor was proposed as adaptive. Cross-sectional correlations among the perfectionism dimensions and symptoms of psychopathology fit well with the adaptive versus maladaptive model. In addition, Socially Prescribed Perfectionism showed a robust predictive relation to 7th-grade internalizing symptoms, especially depression, in boys. Results are discussed in the context of the cultural and socioeconomic characteristics of this African American sample and suggestions for future research are provided.  相似文献   
6.
7.
The glomerular layer of the olfactory bulb contains a substantial population of dopaminergic neurons. We determined the quantity and location of D1 and D2 dopamine receptors which are the presumed targets of these neurons. Binding of the D1 selective ligand [3H]SCH23390 was slightly above background and was distributed through all layers of the bulb except the olfactory nerve layer. In contrast there were relatively high levels of [3H]spiperone binding to D2 DA receptors in the glomerular and olfactory nerve layers. The presence of relatively high concentrations of D2 DA receptors in both the nerve layer and glomerular layer suggests the novel hypothesis that these receptors may be localized on terminals of the olfactory nerve.  相似文献   
8.
This study was undertaken to assess the frequency of significant esophageal involvement in the Zollinger-Ellison syndrome (ZES). In a consecutive series of 24 patients with this disease, 9 (37%) showed endoscopic evidence of acid-induced esophageal lesions ranging from erosive inflammation to ulceration with massive bleeding, severe stricture formation, and perforation. In 3 cases, pronounced esophagitis was known 1–5 years before the underlying disease was diagnosed. Severe esophageal complications developed despite treatment with antisecretory drugs. It is emphasized that the best way to limit such complications is by excision of the underlying gastrin-secreting tumor(s) when possible.
Resumen El presente estudio fue emprendido con el propósito de determinar la frecuencia de afección ácido péptica significativa del esófago en pacientes con síndrome de Zollinger-Ellison. En una serie de 24 pacientes consecutivos con esta enfermedad, 9 (37%) exhibieron evidencia endoscópica de lesiones esofágicas inducidas por ácido, las cuales variaron entre inflamación erosiva y ulceración con sangrado masivo, estrechez severa, y perforación. En 3 pacientes se conocía la existencia de esofagitis severa entre 1 y 5 años antes del diagnóstico de la enfermedad de base. Se desarrollaron graves complicaciones esofágicas a pesar del tratamiento con drogas antisecretorias en 3 pacientes. Se hace enfasis en que la mejor manera de disminuir tales complicaciones es mediante la resección del tumor(es) secretor de gastrina, cuando ello sea posible.

Résumé Nous avons entrepris cette étude pour établir la fréquence de participation oesophagienne dans le syndrome de Zollinger-Ellison. Pour une série de 24 patients présentant cette maladie, 9 (37%) avaient à l'endoscopie des lésions oesophagiennes dues à l'acidité allant de l'érosion inflammatoire à l'ulcération avec saignement important, sténose sévère, et perforation. Dans 3 cas, une oesophagite importante était connue 1–5 ans avant que la maladie sous-jacente soit diagnostiquée. Des complications oesophagiennes sévères se sont produites malgré le traitement antisécrétoire. Nous insistons sur le fait que le meilleur moyen de limiter ces complications est d'exciser chaque fois que possible la ou les tumeurs sous-jacentes sécrétant la gastrine.


Presented at the International Association of Endocrine Surgeons in Toronto, Ontario, Canada, September, 1989.

Supported by grants from the Swedish Medical Research Council, the Swedish Society of Medicine, the Anders Otto Swärd Foundation, and the Surgery Foundation of Skövde Central Hospital.  相似文献   
9.
A technique for transperineal high-dose-rate (HDR) prostate brachytherapy and needle biopsy in a standard 1.5 T MRI scanner is demonstrated. In each of eight procedures (in four patients with intermediate to high risk localized prostate cancer), four MRI-guided transperineal prostate biopsies were obtained followed by placement of 14-15 hollow transperineal catheters for HDR brachytherapy. Mean needle-placement accuracy was 2.1 mm, 95% of needle-placement errors were less than 4.0 mm, and the maximum needle-placement error was 4.4 mm. In addition to guiding the placement of biopsy needles and brachytherapy catheters, MR images were also used for brachytherapy treatment planning and optimization. Because 1.5 T MR images are directly acquired during the interventional procedure, dependence on deformable registration is reduced and online image quality is maximized.  相似文献   
10.
Transluminal angioplasty of the vertebral and basilar artery   总被引:4,自引:0,他引:4  
Transluminal angioplasty of brachiocephalic vessels for atherosclerotic lesions is now being performed in selected cases. We have thus far treated 17 cases of vertebral artery stenosis and one case of basilar artery stenosis by intravascular balloon dilatation techniques. Clinical presenting symptoms included vertebral basilar insufficiency, repeated transient ischemic attacks (TIAs), and multiple strokes. We performed successful transluminal angioplasty in 16 patients with marked narrowing (greater than 70%) of the dominant vertebral artery from atherosclerosis. One patient with basilar artery stenosis with tandem atherosclerotic lesions was also treated by angioplasty techniques. Repeat angiography at 3- to 12-month intervals has revealed continued patency at the angioplasty site. Complications occurred in our one patient with basilar artery angioplasty, who suffered a brainstem infarction after treatment, and in one patient who had a TIA after bilateral vertebral artery angioplasty. Two other patients had residual vertebral stenosis but remained asymptomatic after the procedure. All other patients who had successful dilatation were asymptomatic at 6 months to 2 years (mean, 15 months) of follow-up. These initial studies indicate that vertebral artery angioplasty may be effective for treating high-grade atherosclerotic lesions and for improving blood flow to the posterior circulation. Angioplasty of the basilar artery is technically more difficult and has a higher degree of risk because of the many perforating branches supplying the brainstem.  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