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   3860篇
  免费   293篇
  国内免费   24篇
耳鼻咽喉   15篇
儿科学   182篇
妇产科学   61篇
基础医学   320篇
口腔科学   53篇
临床医学   506篇
内科学   486篇
皮肤病学   20篇
神经病学   258篇
特种医学   313篇
外科学   405篇
综合类   54篇
预防医学   298篇
眼科学   820篇
药学   123篇
肿瘤学   263篇
  2021年   58篇
  2020年   27篇
  2019年   59篇
  2018年   55篇
  2017年   54篇
  2016年   48篇
  2015年   56篇
  2014年   74篇
  2013年   141篇
  2012年   161篇
  2011年   199篇
  2010年   103篇
  2009年   126篇
  2008年   138篇
  2007年   153篇
  2006年   168篇
  2005年   181篇
  2004年   166篇
  2003年   140篇
  2002年   132篇
  2001年   127篇
  2000年   135篇
  1999年   82篇
  1998年   70篇
  1997年   58篇
  1996年   66篇
  1995年   52篇
  1994年   43篇
  1993年   48篇
  1992年   82篇
  1991年   76篇
  1990年   64篇
  1989年   85篇
  1988年   77篇
  1987年   80篇
  1986年   63篇
  1985年   82篇
  1984年   63篇
  1983年   38篇
  1982年   49篇
  1981年   34篇
  1980年   44篇
  1979年   42篇
  1978年   42篇
  1977年   40篇
  1976年   28篇
  1975年   25篇
  1974年   24篇
  1968年   22篇
  1966年   20篇
排序方式: 共有4177条查询结果,搜索用时 31 毫秒
91.
This research explored the biological and social support relationship between youth orphaned due to AIDS and his/her caregiver to identify protective factors that are related to positive mental health outcomes. These youth have significantly higher levels of depression, anxiety, and post-traumatic stress (PTS) symptoms compared to those orphaned due to other causes and non-orphans. Using a 2009 cross-sectional data-set from South Africa, 254 youth orphaned due to AIDS were purposively selected from the overall sample of 732 to further examine this caregiver relationship. Caregiver relation was analyzed in several combinations to determine if it was significantly related to mental health outcomes, with only anxiety showing significance. Those living with a biological parent had significantly higher anxiety symptoms than those living with a grandparent, other kin, or non-kin. Anxiety was also significantly related to an increased age, lower levels of emotional support, and lower levels of instrumental/financial support (R2 = .153). Age was the only significant variable from the model that was related to depression symptoms (R2 = .111). PTS symptoms were related to increases in age, lower levels of emotional support, instrumental/financial support, and satisfaction with the caregiver (R2 = .194). Gender and age were related to suicidal tendencies, specifically boys were 2.26 times more likely to exhibit suicidal tendencies compared to girls, and every yearly increase in age results in the youth being 1.22 times more likely to exhibit suicidal tendencies. Strengthening the caregiver’s ability to provide social support for the child is critical, irrespective of any biological kin relationship.  相似文献   
92.
Metabolic Brain Disease - Parkinson’s disease (PD) is a neurodegenerative disorder etiologically linked to the loss of substantia nigra (SN) dopaminergic neurons in the mid-brain. The...  相似文献   
93.
94.
Forty patients were treated for cardiogenic shock secondary to acute myocardial infarction. Twenty-one (group 1) were treated with intraaortic balloon counterpulsation and 19 (group 2) were treated with counterpulsation and coronary artery bypass grafting. The groups were similar in age, incidence of previous infarction, initial hemodynamics and coronary anatomy. The in-hospital mortality between group 1 (52.4%) and group 2 (42.1%) was not significantly different. The difference in long-term mortality between group 1 and group 2 was substantially different (71.4% vs 47.3%). The subset of group 2 (n = 12) that underwent reperfusion and counterpulsation within 16 hours from the onset of symptoms of infarction had a lower mortality (25.0%) than the subset (n = 7) that underwent operation more than 18 hours after the onset of symptoms (71.4%). The long-term mortality in the subset of group 2 patients operated on within 16 hours after the onset of infarction was significantly different from that in group 1 (25.0% vs 71.4%, p less than 0.03). The data suggest that reperfusion with counterpulsation is more effective when carried out early. Patients who develop shock more than 18 hours after the onset of symptoms of infarction appear to benefit most if treated with counterpulsation alone.  相似文献   
95.
96.

Introduction

Surgical site infection (SSI) is an infection occurring in an incisional wound within 30 days of surgery and significantly affects patients undergoing colorectal surgery. This study examined a multi-institutional dataset to determine risk factors for SSI following colorectal resection.

Methods

Data on 386 patients who underwent colorectal resection in three institutions were accrued. Patients were identified using a prospective SSI database and hospital records. Data are presented as median (interquartile range), and logistic regression analysis was used to identify risk factors.

Results

Patients (21.5 %) developed a postoperative SSI. The median time to the development of SSI was 7 days (5–10). Of all infections, 67.5 % were superficial, 22.9 % were deep and 9.6 % were organ space. In univariate analysis, an ASA grade of II (RR 0.6, CI 0.3–0.9, P?=?0.019), having an elective procedure (RR 0.4, CI 0.2–0.6, P?<?0.001), using a laparoscopic approach (RR 0.5, CI 0.3–0.9, P?=?0.019), having a daytime procedure (RR 0.3, CI 0.1–0.7, P?=?0.006) and having a clean/contaminated wound (RR 0.4, CI 0.2–0.7, P?=?0.001) were associated with reduced risk of SSI. In multivariate analysis, an ASA grade of IV (RR 3.9, CI 1.1–13.7, P?=?0.034), a procedure duration over 3 h (RR 4.3, CI 2.3–8.2, P?<?0.001) and undergoing a panproctocolectomy (RR 6.5, CI 1.0–40.9, P?=?0.044) were independent risk factors for SSI. Those who developed an SSI had a longer duration of inpatient stay (22 days [16–31] vs 15 days [10–26], P?<?0.001).

Conclusions

Patients who develop an SSI have a longer duration of inpatient stay. Independent risk factors for SSI following colorectal resection include being ASA grade IV, having a procedure duration over 3 h, and undergoing a panproctocolectomy.
  相似文献   
97.
98.
99.
Clickable poly(ethylene glycol) (PEG) derivatives are used with two sequential aqueous two‐phase systems to produce microsphere‐based scaffolds for cell encapsulation. In the first step, sodium sulfate causes phase separation of the clickable PEG precursors and is followed by rapid geleation to form microspheres in the absence of organic solvent or surfactant. The microspheres are washed and then deswollen in dextran solutions in the presence of cells, producing tightly packed scaffolds that can be easily handled while also maintaining porosity. Endothelial cells included during microsphere scaffold formation show high viability. The clickable PEG‐microsphere‐based cell scaffolds open up new avenues for manipulating scaffold architecture as compared with simple bulk hydrogels.

  相似文献   

100.
Juvenile and adenomatous gastrointestinal polyposis   总被引:3,自引:0,他引:3  
Summary This is the fourth report of a case showing an association between juvenile and adenomatous polyposis. Starting at age 14, this patient underwent multiple polypectomies and gastrointestinal resections over a 15-year period. Although initial biopsies were diagnosed as juvenile polyps, later biopsies showed both adenomatous polyps and large polypoid masses with a mixture of juvenile and adenomatous features. Several typical small hyperplastic polyps were also found in the stomach. This case contrasts with the previous three cases in that the gastrointestinal tract is more widely involved and in that there is an unusual marked hyperplasia of argentaffin-and argyrophil-positive cells. The case reported here strengthens the relation between adenomatous polyposis and juvenile polyposis.  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