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   1429篇
  免费   71篇
  国内免费   11篇
耳鼻咽喉   40篇
儿科学   52篇
妇产科学   36篇
基础医学   186篇
口腔科学   45篇
临床医学   161篇
内科学   224篇
皮肤病学   13篇
神经病学   92篇
特种医学   106篇
外科学   261篇
综合类   26篇
预防医学   123篇
眼科学   10篇
药学   95篇
中国医学   1篇
肿瘤学   40篇
  2021年   23篇
  2020年   12篇
  2018年   15篇
  2017年   12篇
  2016年   14篇
  2015年   18篇
  2014年   23篇
  2013年   51篇
  2012年   49篇
  2011年   74篇
  2010年   37篇
  2009年   35篇
  2008年   48篇
  2007年   54篇
  2006年   58篇
  2005年   70篇
  2004年   65篇
  2003年   66篇
  2002年   54篇
  2001年   32篇
  2000年   45篇
  1999年   34篇
  1998年   19篇
  1997年   21篇
  1996年   14篇
  1995年   18篇
  1992年   22篇
  1991年   28篇
  1990年   25篇
  1989年   24篇
  1988年   20篇
  1987年   31篇
  1986年   29篇
  1985年   30篇
  1984年   30篇
  1983年   19篇
  1982年   19篇
  1981年   16篇
  1980年   11篇
  1979年   24篇
  1978年   13篇
  1977年   13篇
  1976年   13篇
  1975年   20篇
  1974年   16篇
  1973年   13篇
  1972年   15篇
  1971年   16篇
  1970年   18篇
  1969年   12篇
排序方式: 共有1511条查询结果,搜索用时 15 毫秒
1.
A retrospective study of 1058 liver transplant recipients was performed to determine: (i) the incidence, etiology, timing, clinical features and treatment of refractory ascites (RA), (ii) risk factors for RA development, (iii) predictors of RA disappearance, (iv) predictors of survival following RA and (v) the impact of RA on patient survival. Sixty-two patients (5.9%) developed RA and its disappearance occurred in 27/62 cases. Patients having hepatitis C virus (HCV) had a significantly higher hazard rate of developing RA (p < 0.00001). No other baseline characteristic was associated with RA. Cox stepwise regression analysis of the hazard rate of RA disappearance found two significant factors: HCV recurrence as the reason for developing RA implied a poorer outcome (p = 0.006), whereas an unknown reason implied a favorable outcome (p = 0.02). In addition, survival following RA was significantly poorer among patients having bacterial peritonitis or HCV recurrence. Finally, the mortality rate was significantly (nearly 8.6 times) higher in patients following RA development while it was ongoing (p < 0.00001); however, if the RA disappeared, then the additional risk of death also disappeared. This study illustrates the importance of developing an optimal treatment strategy to (i) effectively treat RA if it develops and (ii) prevent hepatitis C recurrence.  相似文献   
2.
Both dopamine D1 and D2 receptors are present in rat retina. D1 receptors are positively coupled to adenylyl cyclase, while D2 receptors are negatively coupled. After intraocular administration of the neurotoxin 6-hydroxydopamine (6-OHDA) there is depletion of retinal dopamine by about 90%, as well as a decrease of the number of D1 and D2 receptor binding sites. Following the 6-OHDA lesion, there is an enhancement of the D1 receptor-stimulated accumulation of cyclic-AMP and a loss of D2 receptor-inhibited accumulation of cyclic-AMP. Our results suggest that some of the retinal D2 receptors are coupled to adenylyl cyclase and some are not.  相似文献   
3.
Preoperative percutaneous drainage of diverticular abscesses   总被引:5,自引:0,他引:5  
To define the role of percutaneous catheter drainage in the initial management of diverticular abscess, we reviewed 19 patients who were followed for an average of 17.4 months after drainage. All patients had large paracolic or pelvic abscesses with a mean size of 8.9 cm. There were no complications related to catheter placement, and 15 patients (79 percent) required drainage for less than 3 weeks. Sepsis resolved rapidly, and only two patients (11 percent) had persistent fever or leukocytosis beyond the third day of drainage. Routine sinography revealed fistulous communications to the colon in nine patients (47 percent), but only three (16 percent) had grossly feculent drainage. Fourteen patients (74 percent) completed the treatment plan of preoperative catheter drainage followed by single-stage sigmoid colectomy and primary anastomosis without complications. Two patients refused operation, one of whom died 16 days postoperatively from recurrent sepsis and end-stage pulmonary disease. The three patients with fecal fistulas all had inadequate control of infection, suggesting the need for early operation and fecal diversion in such cases. We conclude that preoperative percutaneous catheter drainage obviates the need for colostomy and multiple-stage surgery in approximately three-fourths of patients with large diverticular abscesses.  相似文献   
4.
汪南华  王锐  冷宗康  彭司勋 《药学学报》1990,25(12):920-925
缩氨基硫脲类化合物有抗肿瘤、抗病毒和抗菌等多种药理活性。Barret等首次报道了乙二醛二缩氨基硫脲(Ⅰ)的抗疟活性。Klayman等研究了缩  相似文献   
5.
A qualitative, visually interpreted, rapid, and synthetic peptide-based anti-human immunodeficiency virus-1 (HIV) antibody immunoassay has been developed that may be of value in situations in which rapid determination of HIV-1 status is important. Because questions have been raised about the accuracy of rapid anti-HIV-1 assays, the sensitivity, specificity, interobserver and intraobserver variability of the Genie HIV-1 assay (Genetics Systems, Seattle, WA) were determined. Sera from 56 patients with HIV-1 infections documented by enzyme immunoassay and western blot tested positive by this assay. Enzyme immunoassay- and western blot-negative sera from 30 visceral organ transplant donors were negative using the Genie assay. Specificity was examined further by testing sera from 29 patients hospitalized with a variety of medical disorders, including acute bacterial pneumonia, acute myocardial infarction, monoclonal gammopathy, and high titer antinuclear or antimitochondrial antibodies. Two of these patients were reactive with the enzyme immunoassay, both of which tested negative by western blot. All 29 tested negative using the Genie assay. In addition, sera from five patients with repeatedly reactive enzyme immunoassays and negative western blots tested negative by the Genie system. There was 100% agreement in interobserver and intraobserver studies. With the western blot as the reference method, the Genie assay exhibited 100% sensitivity and specificity and there was no observer variability.  相似文献   
6.
7.
Cryptic osteoid osteoma of the cranium: case report   总被引:1,自引:0,他引:1  
Osteoid osteoma is an uncommon benign tumor of bone that rarely involves the cranium. If often causes local pain that is worse at night, characteristically relieved by aspirin, and does not correlate with the size of the lesion. The diagnosis depends on skull radiographs and computed tomography. This report describes a case in which radiographs showed nothing abnormal. The diagnosis and operative localization were accomplished with radionuclide bone scanning. Thus, the possibility of radiographically cryptic lesions must be considered in the evaluation of atypical head pain syndromes.  相似文献   
8.
9.
Summary A suspension of cells from embryonic day 21 fetal pig ventral mesencephalon was transplanted into the striatum of 20 immunosuppressed rats with 6-hydroxydopamine-induced lesions of the nigrostriatal dopamine pathway. Of these rats, 15 showed reduction of amphetamine-induced ipsilateral rotation by 9 weeks and complete reversal of rotation by 14–17 weeks. Animals maintained stable reversal of rotations (contralateral direction) until cessation of Cyclosporin A (CyA) treatment at 15–20 weeks. Within 4–9 weeks after CyA removal, these rats showed exclusively ipsilateral rotations during behavioral testing which were comparable to pre-transplant levels, suggesting that the grafts were rejected upon cessation of CyA treatment. Rats were sacrificed and tyrosine hydroxylase (TH) immunohistochemistry was performed at several time points, both on and off CyA, to examine a possible correlation between the degree of rotational behavior and the number of TH- positive surviving grafted cells. Staining showed large numbers (230–12,329) of TH-positive surviving cells in animals displaying a high degree of rotational correction (1.6 to -9.6 net ipsilateral rotations/min) after cessation of CyA treatment. Two control groups, those transplanted with nonneuronal cells from the pig ventral mesencephalon (n=5) and those receiving only daily CyA injections (n=4) showed no significant reduction of net ipsilateral rotations throughout the experiment. No TH-positive surviving cells were seen in the one non-neuronal transplant analyzed. This data demonstrates long-term retention of xenografted tissue with immunosuppression and its concomitant restoration of normal motor behavior in the rat model of Parkinson's disease.  相似文献   
10.
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