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   18637篇
  免费   1201篇
  国内免费   199篇
耳鼻咽喉   499篇
儿科学   327篇
妇产科学   226篇
基础医学   2780篇
口腔科学   273篇
临床医学   1459篇
内科学   4011篇
皮肤病学   508篇
神经病学   1333篇
特种医学   1067篇
外科学   3048篇
综合类   117篇
现状与发展   1篇
一般理论   2篇
预防医学   716篇
眼科学   562篇
药学   1522篇
中国医学   188篇
肿瘤学   1398篇
  2023年   118篇
  2022年   377篇
  2021年   571篇
  2020年   290篇
  2019年   453篇
  2018年   573篇
  2017年   400篇
  2016年   576篇
  2015年   855篇
  2014年   1015篇
  2013年   1130篇
  2012年   1656篇
  2011年   1533篇
  2010年   945篇
  2009年   756篇
  2008年   1137篇
  2007年   1109篇
  2006年   1031篇
  2005年   889篇
  2004年   735篇
  2003年   627篇
  2002年   577篇
  2001年   393篇
  2000年   305篇
  1999年   245篇
  1998年   122篇
  1997年   95篇
  1996年   78篇
  1995年   64篇
  1994年   63篇
  1993年   45篇
  1992年   125篇
  1991年   138篇
  1990年   121篇
  1989年   92篇
  1988年   93篇
  1987年   129篇
  1986年   81篇
  1985年   71篇
  1984年   47篇
  1983年   44篇
  1982年   36篇
  1981年   25篇
  1980年   21篇
  1979年   33篇
  1978年   45篇
  1977年   18篇
  1976年   18篇
  1975年   18篇
  1974年   18篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
941.
BackgroundThis pilot study aimed to investigate the current status of e‐cigarettes (ECs) use patterns among patients with chronic airway disease or chronic respiratory symptoms and the effects of ECs use on respiratory and mental health.MethodsA cross‐sectional survey was conducted at the outpatient clinic of eight teaching hospitals in South Korea between November 2019 and December 2019. All adult ECs users (19 years and above) who visited the outpatient clinic as a patient with chronic airway disease or chronic respiratory symptoms were eligible to participate in this study.ResultsA total of 51 subjects responded to the survey. Most of the participants were male (92.2%) and the mean age was 41.8 years. Dominant airway diseases were asthma and chronic obstructive pulmonary disease. Most of the subjects had a history of cigarette smoking, and 19 subjects were dual users of current cigarettes and ECs. Most of the subjects started ECs use due to health‐related reasons. When comparing exclusive ECs users and dual users, St. George''s respiratory questionnaire (SGRQ) scores, the proportion of cases with moderate to severe depressive symptoms, and average Fagerstrom test for nicotine dependence scores for ECs were higher in dual users than exclusive ECs users (mean 4.64 vs. 2.38, p = 0.006), respectively.ConclusionMost of the subjects started ECs use due to health concerns, but dual users have more respiratory symptoms and higher nicotine dependence in this pilot study. One hypothesis that comes from these results is that greater nicotine dependence may influence behaviours, habits, and views about ECs. These preliminary observations need confirmation in a large cohort.  相似文献   
942.

Background

Spleen-preserving distal pancreatectomy can be performed safely and effectively by resecting both splenic vessels (Warshaw procedure) [14]. This simplified spleen-preserving technique might also be applied to minimally invasive distal pancreatectomy of benign and borderline malignant tumor [5, 6].

Methods

Although the conservation of both splenic vessels is paramount to preserving the spleen during laparoscopic distal pancreatectomy, preservation of the splenic vessels is not always possible, especially under the following conditions: (1) relatively large tumor, (2) associated with chronic pancreatitis, (3) tumor abutting splenic vascular structures, and (4) bleeding during the splenic vessel conserving procedure, which are potential indications of laparoscopic extended Warshaw procedure. Patient preparation and position was the same as that described in our previous study [7].

Results

During the study’s time period, 38 consecutive patients underwent laparoscopic spleen-preserving distal pancreatectomy. Of those, five patients underwent a laparoscopic extended Warshaw procedure, which all included among 16 patients of extended distal pancreatectomy by dividing the pancreas at the pancreatic neck. All patients were women with a median age of 55 (range, 38–75) years. Median total operation time and blood loss were 215 (range, 200–386) minutes and 100 (range, 0–300) ml, respectively. The median length of hospital stay was 8 (range, 5–15) days. All of postoperative complications (two grade A and two grade B postoperative pancreatic fistula; one grade A bleeding) were able to be treated conservatively. During the median follow-up period of 11 (range, 7–42) months, one focal splenic infarction and one gastric varix were noted; however, no clinically significant complications were reported.

Conclusions

Laparoscopic spleen-preserving extended distal pancreatectomy with resection of both the splenic vessels is feasible and safe [8]. This surgical technique is thought to increase the chance of preservation of the spleen with minimally invasive distal pancreatectomy in well-selected benign or borderline malignant tumor of the distal pancreas.  相似文献   
943.
Background The intimate association between glial cells and neurons within the enteric nervous system has confounded careful examination of the direct responsiveness of enteric glia to different neuroligands. Therefore, we aimed to investigate whether neurotransmitters known to elicit fast excitatory potentials in enteric nerves also activate enteric glia directly. Methods We studied the effect of acetylcholine (ACh), serotonin (5‐HT), and adenosine triphosphate (ATP) on intracellular Ca2+ signaling using aequorin‐expressing and Fluo‐4 AM‐loaded CRL‐2690 rat and human enteric glial cell cultures devoid of neurons. The influence of these neurotransmitters on the proliferation of glia was measured and their effect on the expression of c‐Fos as well as glial fibrillary acidic protein (GFAP), Sox10, and S100 was examined by immunohistochemistry and quantitative RT‐PCR. Key Results Apart from ATP, also ACh and 5‐HT induced a dose‐dependent increase in intracellular Ca2+ concentration in CRL‐2690 cells. Similarly, these neurotransmitters also evoked Ca2+ transients in human primary enteric glial cells obtained from mucosal biopsies. In contrast with ATP, stimulation with ACh and 5‐HT induced early gene expression in CRL‐2690 cells. The proliferation of enteric glia and their expression of GFAP, Sox10, and S100 were not affected following stimulation with these neurotransmitters. Conclusions & Inferences We provide evidence that enteric glial cells respond to fast excitatory neurotransmitters by changes in intracellular Ca2+. On the basis of our experimental in vitro setting, we show that enteric glia are not only directly responsive to purinergic but also to serotonergic and cholinergic signaling mechanisms.  相似文献   
944.
945.
This study aimed to investigate the associations between the expression of redox-related proteins which regulate reactive oxygen species (ROS) production and the histologic factors in phyllodes tumor (PT). We used tissue microarrays to analyze 193 PTs and performed immunohistochemical staining against five redox-related proteins including catalase, thioredoxin reductase (TxNR), glutathione S-transferase π (GST π), thioredoxin interacting protein (TxNIP), and manganese superoxide dismutase (MnSOD). We then compared the immunohistochemical results and histologic parameters. The 193 PTs were classified as benign (n = 145, 75.1 %), borderline (n = 33, 17.1 %), and malignant (n = 15, 7.8 %). With worsening histologic grade, the expression of catalase, TxNR, TxNIP, and MnSOD in the stromal component increased (P < 0.001), and GST π and MnSOD expression in the epithelial component increased (P = 0.014, and 0.038). Significant associations were found between the expression of catalse–TxNR, catalase–TxNIP, catalase–MnSOD, TxNR–TxNIP, TxNR–MnSOD, and TxNIP–MnSOD in both the epithelial and stromal components (P < 0.05). This study confirmed that the stromal expression of catalase, TxNR, TxNIP, and MnSOD increased with worsening histologic grade in PT, reflecting the change in ROS production during the malignant transformation of PT.  相似文献   
946.
In keeping with the increasing utilization of CT examinations, the greater concern about radiation hazards from examinations has been addressed. In this regard, CT radiation dose optimization has been given a great deal of attention by radiologists, referring physicians, technologists, and physicists. Dose-saving strategies are continuously evolving in terms of imaging techniques as well as dose management. Consequently, regular updates of this issue are necessary especially for radiologists who play a pivotal role in this activity. This review article will provide an update on how we can optimize CT dose in order to maximize the benefit-to-risk ratio of this clinically useful diagnostic imaging method.  相似文献   
947.
948.
Materials with strong correlations are prone to spin and charge instabilities, driven by Coulomb, magnetic, and lattice interactions. In materials that have significant localized and itinerant spins, it is not obvious which will induce order. We combine electrical transport, X-ray magnetic diffraction, and photoemission studies with band structure calculations to characterize successive antiferromagnetic transitions in GdSi. GdSi has both sizable local moments and a partially nested Fermi surface, without confounding contributions from orbital effects. We identify a route to incommensurate order where neither type of moment dominates, but is rooted in cooperative feedback between them. The nested Fermi surface of the itinerant electrons induces strong interactions between local moments at the nesting vector, whereas the ordered local moments in turn provide the necessary coupling for a spin-density wave to form among the itinerant electrons. This mechanism echoes the cooperative interactions between electrons and ions in charge-density–wave materials, and should be germane across a spectrum of transition-metal and rare-earth intermetallic compounds.  相似文献   
949.
950.
A 51-year-old diabetic woman was referred to our unit with a history of increasing pain in her right thigh and gait disturbance, 10 days following surgery for treatment of stress urinary incontinence with a transobturator tape. Examination elicited a tender right thigh associated with swelling and erythema. Inspection of the vagina revealed an exposed mesh through the vaginal erosion. Plain radiographs and magnetic resonance imaging revealed large thigh abscesses suggestive of gas gangrene from the pelvis to the calf. The mesh was completely removed; extensile incisions, as well as aggressive debridement of all necrotic tissue in the thigh and calf, were performed. A diagnosis of necrotizing fasciitis with gas extending to the lower leg level was confirmed. After mesh removal, abscess drainage and debridement, the patient recovered with antibiotics and daily wound care. Three months after the operation, the patient showed no recurrence of the infection.  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