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   2728篇
  免费   195篇
  国内免费   4篇
耳鼻咽喉   29篇
儿科学   113篇
妇产科学   62篇
基础医学   468篇
口腔科学   39篇
临床医学   221篇
内科学   648篇
皮肤病学   44篇
神经病学   206篇
特种医学   118篇
外科学   305篇
综合类   9篇
一般理论   1篇
预防医学   261篇
眼科学   24篇
药学   135篇
中国医学   5篇
肿瘤学   239篇
  2023年   20篇
  2022年   38篇
  2021年   71篇
  2020年   53篇
  2019年   75篇
  2018年   126篇
  2017年   48篇
  2016年   64篇
  2015年   84篇
  2014年   125篇
  2013年   157篇
  2012年   229篇
  2011年   212篇
  2010年   116篇
  2009年   114篇
  2008年   171篇
  2007年   185篇
  2006年   202篇
  2005年   175篇
  2004年   153篇
  2003年   146篇
  2002年   141篇
  2001年   25篇
  2000年   15篇
  1999年   19篇
  1998年   24篇
  1997年   14篇
  1996年   25篇
  1995年   10篇
  1994年   17篇
  1993年   11篇
  1992年   12篇
  1991年   9篇
  1990年   9篇
  1989年   6篇
  1987年   3篇
  1986年   3篇
  1984年   2篇
  1983年   1篇
  1982年   1篇
  1981年   2篇
  1979年   1篇
  1978年   1篇
  1977年   1篇
  1976年   1篇
  1975年   2篇
  1974年   1篇
  1972年   3篇
  1967年   1篇
  1955年   1篇
排序方式: 共有2927条查询结果,搜索用时 15 毫秒
991.
992.
Since deforestation has recently been associated with increased mercury load in the Amazon, the problem of mercury exposure is now much more widespread than initially thought. A previous exploratory study suggested that fruit consumption may reduce mercury exposure. The objectives of the study were to determine the effects of fruit consumption on the relation between fish consumption and bioindicators of mercury (Hg) exposure in Amazonian fish-eating communities. A cross-sectional dietary survey based on a 7-day recall of fish and fruit consumption frequency was conducted within 13 riparian communities from the Tapajós River, Brazilian Amazon. Hair samples were collected from 449 persons, and blood samples were collected from a subset of 225, for total and inorganic mercury determination by atomic absorption spectrometry. On average, participants consumed 6.6 fish meals/week and ate 11 fruits/week. The average blood Hg (BHg) was 57.1 +/- 36.3 microg/L (median: 55.1 microg/L), and the average hair-Hg (HHg) was 16.8 +/- 10.3 microg/g (median: 15.7 microg/g). There was a positive relation between fish consumption and BHg (r = 0.48; P<0.0001), as well as HHg (r =0.34; P<0.0001). Both fish and fruit consumption entered significantly in multivariate models explaining BHg (fish: beta = 5.6, P<0.0001; fruit: beta = -0.5, P = 0.0011; adjusted model R2 = 36.0%) and HHg levels (fish: beta = 1.2, P<0.0001; fruit: beta = -0.2, P = 0.0002; adjusted model R2 = 21.0%). ANCOVA models showed that for the same number of fish meals, persons consuming fruits more frequently had significantly lower blood and HHg concentrations. For low fruit consumers, each fish meal contributed 9.8 microg/L Hg increase in blood compared to only 3.3 microg/L Hg increase for the high fruit consumers. In conclusion, fruit consumption may provide a protective effect for Hg exposure in Amazonian riparians. Prevention strategies that seek to maintain fish consumption while reducing Hg exposure in fish-eating communities should be pursued.  相似文献   
993.
ANXA1, first described in the context of inflammation, appears to be deregulated in many cancers and increased in melanomas compared with melanocytes. To date, few studies have investigated the role of ANXA1 in melanoma progression. Furthermore, this protein is expressed by various cell types, including immune and endothelial cells. We therefore analyzed the specific roles of ANXA1 using melanoma and stromal cells in two human cell lines (A375-MA2 and SK-MEL-28) in vitro and in Anxa1 null C57Bl6/J mice bearing B16Bl6 tumors. We report decreased proliferation in both ANXA1 siRNA A375-MA2 and SK-MEL-28, but cell-dependent effects of ANXA1 in migration in vitro. However, we also observed a significant decrease of B16Bl6 tumor growth associated with a reduction of Ki-67 positive cells in Anxa1 null mice compared with wild-type mice. Interestingly, we also found a significant reduction of spontaneous metastases, which can be attributed to decreased angiogenesis concomitantly with greater immune cell presence in the Anxa1 null stromal context. This study highlights the pejorative role of ANXA1 in both tumor and stromal cells in melanoma, due to its involvement in proliferation and angiogenesis.  相似文献   
994.
Macrophage activation is characterized by pronounced metabolic adaptation. Classically activated macrophages show decreased rates of mitochondrial fatty acid oxidation and oxidative phosphorylation and acquire a glycolytic state together with their pro‐inflammatory phenotype. In contrast, alternatively activated macrophages require oxidative phosphorylation and mitochondrial fatty acid oxidation for their anti‐inflammatory function. Although it is evident that mitochondrial metabolism is regulated during macrophage polarization and essential for macrophage function, little is known on the regulation and role of peroxisomal β‐oxidation during macrophage activation. In this study, we show that peroxisomal β‐oxidation is strongly decreased in classically activated bone‐marrow‐derived macrophages (BMDM) and mildly induced in alternatively activated BMDM. To examine the role of peroxisomal β‐oxidation in macrophages, we used Mfp2?/? BMDM lacking the key enzyme of this pathway. Impairment of peroxisomal β‐oxidation in Mfp2?/? BMDM did not cause lipid accumulation but rather an altered distribution of lipid species with very‐long‐chain fatty acids accumulating in the triglyceride and phospholipid fraction. These lipid alterations in Mfp2?/? macrophages led to decreased inflammatory activation of Mfp2?/? BMDM and peritoneal macrophages evidenced by impaired production of several inflammatory cytokines and chemokines, but did not affect anti‐inflammatory polarization. The disturbed inflammatory responses of Mfp2?/? macrophages did not affect immune cell infiltration, as mice with selective elimination of MFP2 from myeloid cells showed normal monocyte and neutrophil influx upon challenge with zymosan. Together, these data demonstrate that peroxisomal β‐oxidation is involved in fine‐tuning the phenotype of macrophages, probably by influencing the dynamic lipid profile during macrophage polarization.  相似文献   
995.
The results of conventional allogeneic stem cell transplantation (SCT) in refractory hematologic malignancies are poor. Sequential strategies have shown promising results in refractory acute myelogenous leukemia (AML), but have not been validated in a haploidentical (Haplo) transplant setting. We have developed a new sequential approach combining chemotherapy with broad antitumor activity (thiotepa 10?mg/kg, etoposide 400?mg/m2, and cyclophosphamide 1600?mg/m2 from day -15 to day -10), followed after 3 days of rest by a reduced-intensity conditioning regimen (fludarabine 150?mg/m2, i.v. busulfan 6.4?mg/kg, and thymoglobulin 5?mg/kg from day -6 to day -2). High-dose post-transplantation cyclophosphamide was added in cases with Haplo donors. Seventy-two patients (median age, 54 years) with a refractory hematologic malignancy (44 with acute myelogenous leukemia, 7 with acute lymphoblastic leukemia, 15 with myelodysplastic syndrome/myeloproliferative neoplasms, and 6 with lymphomas) were included in this retrospective multicenter study. Donors were Haplo (n?=?27), matched related (MRD; n?=?16), and unrelated (UD; n?=?29). With a median follow-up of 21 months, the 2-year overall survival (OS) and event-free survival (EFS) were 54.7% and 49.3%, respectively, in recipients of Haplo transplants, 49.2% and 43.8%, respectively, in recipients of MRD transplants, and 37.9% and 28%, respectively, in recipients of UD transplants. Compared with UD, the outcomes were improved in Haplo in terms of the incidences of acute grade II-IV graft-versus-host disease (GVHD) (11.1% versus 41.4%; P?<?.001) and GVHD-free, relapse-free survival (44.4 versus 10.3%; P?=?.022). These results support the safety and efficacy of a thiotepa-based sequential approach in allogeneic SCT with a Haplo donor with post-transplantation immune modulation. Thus, in patients with refractory hematologic malignancies, there seems to be no benefit in searching for a UD when a Haplo donor is readily available.  相似文献   
996.

Background

The exact role of IV contrast-enhanced computed tomography (CT) in the diagnosis of necrotizing soft tissue infections (NSTIs) has not yet been established. We aimed to explore the role of CT in patients with clinical suspicion of NSTI and assess its sensitivity and specificity for NSTI.

Methods

The medical records of patients admitted between 2009 and 2016, who received IV contrast-enhanced CT to rule out NSTI, were reviewed. CT was considered positive in case of: (a) gas in soft tissues, (b) multiple fluid collections, (c) absence or heterogeneity of tissue enhancement by the IV contrast, and (d) significant inflammatory changes under the fascia. NSTI was confirmed only by the presence of necrotic tissue during surgical exploration. NSTI was considered absent if surgical exploration failed to identify necrosis, or if the patient was successfully treated non-operatively.

Results

Of the 184 patients, 17 had a positive CT and hence underwent surgical exploration with NSTI being confirmed in 13 of them (76%). Of the 167 patients that had a negative CT, 38 (23%) underwent surgical exploration due to the high clinical suspicion for NSTI and were all found to have non-necrotizing infections; the remaining 129 (77%) were managed non-operatively with successful resolution of symptoms. The sensitivity of CT in identifying NSTI was 100%, the specificity 98%, the positive predictive value 76%, and the negative predictive value 100%.

Conclusions

A negative IV contrast-enhanced CT scan can reliably rule out the need for surgical intervention in patients with initial suspicion of NSTI.
  相似文献   
997.
Leem (French Pharmaceutical Companies) realized an inventory of unmet medical needs in 2006 in France for 12 pathologies. All of them are considered as national public health priorities by the law of August 9th, 2004. Allied to the epidemiological projections, analyses concerned various stages and/or pathology forms, impact of guidelines in clinical practice, therapeutic strategies, marketed therapeutics and pharmacological products in an advanced phase of clinical development. With more than 100 products listed in clinical phase III or pre-registration/marketed for those pathologies, French Pharmaceutical Companies contribute, quasi exclusively, to the development of innovative pharmaceutical products to answer unmet medical needs. This study illustrates the necessity of French Government to support therapeutic innovation led by Pharmaceutical Companies in France.  相似文献   
998.
999.
Garbouj  Myriam  Rangel  Luís F.  Santos  Maria J.  Bahri  Sihem 《Parasitology research》2018,117(6):1933-1939
Parasitology Research - Ceratomyxa gouletti n. sp. is a new parasite described from the gallbladder of the red scorpionfish Scorpaena scrofa (Scorpaeniformes: Scorpaenidae) collected from La...  相似文献   
1000.
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