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   1497篇
  免费   117篇
  国内免费   14篇
耳鼻咽喉   28篇
儿科学   38篇
妇产科学   96篇
基础医学   161篇
口腔科学   181篇
临床医学   97篇
内科学   269篇
皮肤病学   23篇
神经病学   77篇
特种医学   146篇
外科学   190篇
综合类   28篇
预防医学   128篇
眼科学   26篇
药学   63篇
中国医学   1篇
肿瘤学   76篇
  2021年   16篇
  2020年   9篇
  2019年   20篇
  2018年   34篇
  2017年   16篇
  2016年   17篇
  2015年   21篇
  2014年   30篇
  2013年   73篇
  2012年   52篇
  2011年   71篇
  2010年   47篇
  2009年   44篇
  2008年   49篇
  2007年   69篇
  2006年   54篇
  2005年   64篇
  2004年   51篇
  2003年   44篇
  2002年   42篇
  2001年   37篇
  2000年   33篇
  1999年   36篇
  1998年   53篇
  1997年   50篇
  1996年   32篇
  1995年   32篇
  1994年   17篇
  1993年   24篇
  1992年   21篇
  1991年   30篇
  1990年   32篇
  1989年   44篇
  1988年   31篇
  1987年   50篇
  1986年   29篇
  1985年   30篇
  1984年   29篇
  1983年   28篇
  1982年   20篇
  1981年   10篇
  1980年   14篇
  1979年   13篇
  1977年   9篇
  1976年   9篇
  1975年   21篇
  1974年   8篇
  1971年   10篇
  1970年   7篇
  1966年   4篇
排序方式: 共有1628条查询结果,搜索用时 15 毫秒
51.

Background

Gastrointestinal stromal tumors (GIST) are the most common mesenchymal tumors of the gastrointestinal tract. Overall surgical experience with minimally invasive surgery (MIS) has increased; however, published reports on MIS resection of GIST are limited to small, single-institution experiences.

Methods

A total of 397 patients who underwent open surgery (n = 230) or MIS (n = 167) for a gastric GIST between 1998 and 2012 were identified from a multicenter database. The impact of MIS approach on recurrence and survival was analyzed using propensity-score matching by comparing clinicopathologic factors between patients who underwent MIS versus open resection.

Results

There were 19 conversions (10 %) to open; the most common reasons for conversion were tumor more extensive than anticipated (26 %) and unclear anatomy (21 %). On multivariate analysis, smaller tumor size and higher body mass index (BMI) were associated with receipt of MIS. In the propensity-matched cohort (n = 248), MIS resection was associated with decreased length of stay (MIS, 3 days vs open, 8 days) and fewer ≥ grade 3 complications (MIS, 3 % vs open, 14 %) compared with open surgery. High rates of R0 resection and low rates of tumor rupture were seen in both groups. After propensity-score matching, there was no difference in recurrence-free or overall survival comparing the MIS and the open group (both p > 0.05).

Conclusions

An MIS approach for gastric GIST was associated with low morbidity and a high rate of R0 resection. The long-term oncological outcome following MIS was excellent, and therefore the MIS approach should be considered the preferred approach for gastric GIST in well-selected patients.  相似文献   
52.
53.
54.
Oxidative metabolism of the human eosinophil   总被引:14,自引:1,他引:14  
We have compared the oxidative metabolism of human eosinophils (80%-90% purity) to that of neutrophils. Hexose monophosphate (HMP) shunt activity of eosinophils was higher than that of neutrophils under either resting or phagocytizing conditions. Eosinophil HMP shunt activity also was stimulated by phorbol myristate acetate, a membrane- active agent. Eosinophils showed a marked incorporation of 125I into trichloroacetic acid-insoluble material under resting conditions, which increased markedly during phagocytosis. Eosinophils likewise showed a greater reduction of nitroblue tetrazolium dye during phagocytosis than did neutrophils. Measurement of other parameters of oxidative metabolism indicated that eosinophils generated superoxide anion following phagocytosis and also elicited a burst of chemiluminescence similar to that observed during phagocytosis by neutrophils. Measurement of NADPH oxidase activity demonstrated that this enzyme was 3-6 times more active in fractions isolated from eosinophils than in corresponding fractions isolated from neutrophils; this was observed over a range of substrate concentrations. The eosinophil enzyme sedimented differently than the neutrophil enzyme with differential centrifugation; neither showed sedimentation characteristics of peroxidase. These data indicate that eosinophils possess a similar, although in some ways more potent, oxidative burst than neutrophils and are consistent with a role for NADPH oxidase in the initiation of that burst.  相似文献   
55.
OBJECTIVE: Assisting Hispanic immigrants in making culturally acceptable food choices may affect their health for generations. As a relatively new enclave of Hispanics, Scott County, Mississippi, was chosen to study dietary acculturation and health concerns of immigrants. MATERIAL AND METHODS: The research method consisted of interviews with community representatives (N=11), a focus group (N=6), and interviews with Hispanic immigrants (N=18). RESULTS: Community representatives mentioned availability influenced immigrants' food choices and suggested promoting cultural awareness and offering nutrition classes on local ingredients. Food cost, health concepts, food selection, and eating habits of children were salient themes from the focus group and interviews with Hispanics. Hispanic participants mentioned long work hours affect food selection and that U.S. produce lacks freshness and flavor. CONCLUSIONS: Results indicate that an intervention must be formulated that preserves healthful dietary practices and minimizes the negative health aspects of acculturation to the "American diet"  相似文献   
56.
Risk factors for avascular bone necrosis in systemic lupus erythematosus   总被引:6,自引:0,他引:6  
OBJECTIVE: To study the predictive factors for avascular necrosis (AVN) of bone in patients with systemic lupus erythematosus (SLE). METHOD: The records of 38 SLE patients who developed clinically apparent AVN during the course of their disease were reviewed. Information on clinical presentation, corticosteroid usage and autoantibody profiles was obtained, and comparison was made between these patients and 143 consecutive control SLE patients who did not have AVN. RESULTS: The point prevalence of AVN in our SLE population was 12%. Patients with AVN, when compared with controls, had a significantly higher incidence of neurological disease (39% vs 14%; P < 0.001) and Cushingoid body habitus after steroid treatment (79% vs 53%; P = 0.004). The highest cumulative prednisolone dose in 1 and 4 months was significantly higher in the AVN group than the controls (1.8 vs 1.1 and 4.5 vs 2.8 g, respectively; P < 0.01 in both) and showed a linear trend with the incidence of AVN (chi2 test for trend, P < 0.01 in both). Lupus anticoagulant was associated with AVN (P = 0.02, odds ratio 2.88 [1.14- 7.28]). Logistic regression analysis revealed that the highest cumulative prednisolone dose administered in 4 months, the maximum and mean daily prednisolone dosage, and the lupus anticoagulant were independent risk factors for AVN. CONCLUSIONS: Corticosteroid remains the major predisposing factor for AVN in SLE. Patients who require an initial high-dose steroid for disease control are at risk of AVN, especially if they are positive for the lupus anticoagulant or develop Cushingoid habitus after steroid treatment. High-risk patients should be closely monitored so that early AVN can be diagnosed by sensitive techniques such as magnetic resonance imaging and radioisotope bone scanning.   相似文献   
57.
Paul  CC; Baumann  MA 《Blood》1990,75(1):54-58
Spontaneous outgrowth of immortalized Epstein-Barr virus (EBV) infected B-cell clones will occur from cultures of peripheral blood mononuclear cells (PBMNCs) of some persons with a history of EBV infection. We determined that outgrowth of such clones may be reproducibly modulated by supplementation of cultures with the hematopoietic growth factors GM- CSF and interleukin-3 (IL-3). Continuous supplementation of cultures with GM-CSF facilitates emergence of immortalized B-cell clones, whereas supplementation with IL-3 completely prevents their emergence. The effect of GM-CSF may be direct, at least in part, as the proliferation of pure clones of EBV-transformed B lymphocytes was augmented in response to GM-CSF. An indirect mechanism appears to be responsible for the inhibition of transformed B-cell outgrowth in response to IL-3, as IL-3 had no inhibitory effect on proliferation of pure transformed B-cell clones and IL-3-mediated inhibition could be eliminated by antibody neutralization of gamma-interferon (gamma-IFN) or tumor necrosis factor-alpha (TNF-alpha) early in culture. The mechanisms of these effects deserve further study and may have clinical relevance to use of hematopoietic growth factors for support of bone marrow (BM) function in immunocompromised patients.  相似文献   
58.
The impact of the novel basal insulin LY2605541 (LY) on hepatic and nonhepatic glucose uptake (non-HGU) was evaluated. Conscious dogs underwent euglycemic clamps with tracer and hepatic balance measurements. Clamp period infusions were peripheral venous regular insulin (0.1 nmol ⋅ kg−1 ⋅ h−1 [control], n = 6) or LY (bolus [nmol/kg], continuous [nmol ⋅ kg−1 ⋅ h−1]: 0.5, 0.5 [n = 6]; 0.375, 0.375 [n = 5]; 0.25, 0.25 [n = 4]), somatostatin, and glucose, as well as intraportal glucagon (basal). During the clamp, the dogs switched from net hepatic glucose output to uptake (rates reached 2.1 ± 1.2, 0.9 ± 2.1, 8.6 ± 2.3, and 6.0 ± 1.1 µmol ⋅ kg−1 ⋅ min−1 within 5 h in control, LY0.25, LY0.375, and LY0.5, respectively). Non-HGU in LY increased less than in control; the ratio of change from basal in non-HGU to change in net hepatic glucose balance, calculated when glucose infusion rates (GIRs) were ~20 µmol ⋅ kg-1 ⋅ min−1 in all groups, was higher in control (1.17 ± 0.38) versus LY0.25 (0.39 ± 0.33), LY0.375 (−0.01 ± 0.13), and LY0.5 (−0.09 ± 0.07). Likewise, the change from baseline in glucose Rd-to-Ra ratio was greatest in control (1.4 ± 0.3 vs. 0.6 ± 0.4, 0.5 ± 0.2, and 0.6 ± 0.2 in LY0.25, LY0.375, and LY0.5, respectively). In contrast to exogenously administered human insulin, LY demonstrated preferential hepatic effects, similar to endogenously secreted insulin. Therefore, the analog might reduce complications associated with current insulin therapy.  相似文献   
59.
With the ubiquity of mobile devices, the availability of mobile health (mHealth) applications for cardiovascular disease (CVD) has markedly increased in recent years. Older adults represent a population with a high CVD burden and therefore have the potential to benefit considerably from interventions that utilize mHealth. Traditional facility-based cardiac rehabilitation represents one intervention that is currently underutilized for CVD patients and, because of the unique barriers that older adults face, represents an attractive target for mHealth interventions. Despite potential barriers to mHealth adoption in older populations, there is also evidence that older patients may be willing to adopt these technologies. In this review, we highlight the potential for mHealth uptake for older adults with CVD, with a particular focus on mHealth cardiac rehabilitation (mHealth-CR) and evidence being generated in this field.  相似文献   
60.
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