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   8085篇
  免费   412篇
  国内免费   64篇
耳鼻咽喉   93篇
儿科学   142篇
妇产科学   86篇
基础医学   1134篇
口腔科学   248篇
临床医学   474篇
内科学   2042篇
皮肤病学   71篇
神经病学   741篇
特种医学   340篇
外科学   1462篇
综合类   23篇
预防医学   271篇
眼科学   62篇
药学   519篇
中国医学   6篇
肿瘤学   847篇
  2023年   64篇
  2022年   90篇
  2021年   206篇
  2020年   88篇
  2019年   155篇
  2018年   200篇
  2017年   141篇
  2016年   188篇
  2015年   189篇
  2014年   217篇
  2013年   244篇
  2012年   367篇
  2011年   407篇
  2010年   244篇
  2009年   231篇
  2008年   371篇
  2007年   386篇
  2006年   409篇
  2005年   394篇
  2004年   383篇
  2003年   409篇
  2002年   337篇
  2001年   231篇
  2000年   225篇
  1999年   217篇
  1998年   105篇
  1997年   79篇
  1996年   79篇
  1995年   59篇
  1994年   62篇
  1993年   68篇
  1992年   148篇
  1991年   126篇
  1990年   132篇
  1989年   136篇
  1988年   112篇
  1987年   92篇
  1986年   110篇
  1985年   113篇
  1984年   90篇
  1983年   64篇
  1982年   46篇
  1979年   55篇
  1978年   35篇
  1974年   41篇
  1973年   42篇
  1971年   36篇
  1969年   35篇
  1967年   36篇
  1966年   34篇
排序方式: 共有8561条查询结果,搜索用时 687 毫秒
1.
BACKGROUND Minimally invasive surgery for gastric cancer(GC) has gained widespread use as a safe curative procedure especially for early GC.AIM To determine risk factors for postoperative complications after minimally invasive gastrectomy for GC.METHODS Between January 2009 and June 2019, 1716 consecutive patients were referred to our division for primary GC. Among them, 1401 patients who were diagnosed with both clinical and pathological Stage Ⅲ or lower GC and underwent robotic gastrectomy(RG) or laparoscopic gastrectomy(LG) were enrolled. Retrospective chart review and multivariate analysis were performed for identifying risk factors for postoperative morbidity.RESULTS Morbidity following minimally invasive gastrectomy was observed in 7.5% of the patients. Multivariate analyses demonstrated that non-robotic minimally invasive surgery, male gender, and an operative time of ≥ 360 min were significant independent risk factors for morbidity. Therefore, morbidity was compared between RG and LG. Accordingly, propensity-matched cohort analysis revealed that the RG group had significantly fewer intra-abdominal infectious complications than the LG group(2.5% vs 5.9%, respectively; P = 0.038), while no significant differences were noted for other local or systemic complications.Multivariate analyses of the propensity-matched cohort revealed that non-robotic minimally invasive surgery [odds ratio = 2.463(1.070–5.682); P = 0.034] was a significant independent risk factor for intra-abdominal infectious complications.CONCLUSION The findings showed that robotic surgery might improve short-term outcomes following minimally invasive radical gastrectomy by reducing intra-abdominal infectious complications.  相似文献   
2.
3.
4.
Angiotensin II receptor blockers (ARBs) are widely used for the treatment of hypertension. It is believed that treatment with an ARB increases the level of plasma angiotensin II (Ang II) because of a lack of negative feedback on renin activity. However, Ichikawa (Hypertens Res 2001; 24: 641-646) reported that long-term treatment of hypertensive patients with olmesartan resulted in a reduction in plasma Ang II level, though the mechanism was not determined. It has been reported that angiotensin 1-7 (Ang-(1-7)) potentiates the effect of bradykinin and acts as an angiotensin-converting enzyme (ACE) inhibitor. It is known that ACE2, which was discovered as a novel ACE-related carboxypeptidase in 2000, hydrolyzes Ang I to Ang-(1-9) and also Ang II to Ang-(1-7). It has recently been reported that olmesartan increases plasma Ang-(1-7) through an increase in ACE2 expression in rats with myocardial infarction. We hypothesized that over-expression of ACE2 may be related to a reduction in Ang II level and the cardioprotective effect of olmesartan. Administration of 0.5 mg/kg/day of olmesartan for 4 weeks to 12-week-old stroke-prone spontaneously hypertensive rats (SHRSP) significantly reduced blood pressure and left ventricular weight compared to those in SHRSP given a vehicle. Co-administration of olmesartan and (D-Ala7)-Ang-(1-7), a selective Ang-(1-7) antagonist, partially inhibited the effect of olmesartan on blood pressure and left ventricular weight. Interestingly, co-administration of (D-Ala7)-Ang-(1-7) with olmesartan significantly increased the plasma Ang II level (453.2+/-113.8 pg/ml) compared to olmesartan alone (144.9+/-27.0 pg/ml, p<0.05). Moreover, olmesartan significantly increased the cardiac ACE2 expression level compared to that in Wistar Kyoto rats and SHRSP treated with a vehicle. Olmesartan significantly improved cardiovascular remodeling and cardiac nitrite/ nitrate content, but co-administration of olmesartan and (D-Ala7)-Ang-(1-7) partially reversed this anti-remodeling effect and the increase in nitrite/nitrate. These findings suggest that olmesartan may exhibit an ACE inhibitory action in addition to an Ang II receptor blocking action, prevent an increase in Ang II level, and protect cardiovascular remodeling through an increase in cardiac nitric oxide production and endogenous Ang-(1-7) via over-expression of ACE2.  相似文献   
5.
OBJECTIVE: The Karolinska sleepiness scale (KSS) is frequently used for evaluating subjective sleepiness. The main aim of the present study was to investigate the validity and reliability of the KSS with electroencephalographic, behavioral and other subjective indicators of sleepiness. METHODS: Participants were 16 healthy females aged 33-43 (38.1+/-2.68) years. The experiment involved 8 measurement sessions per day for 3 consecutive days. Each session contained the psychomotor vigilance task (PVT), the Karolinska drowsiness test (KDT-EEG alpha & theta power), the alpha attenuation test (AAT-alpha power ratio open/closed eyes) and the KSS. RESULTS: Median reaction time, number of lapses, alpha and theta power density and the alpha attenuation coefficients (AAC) showed highly significant increase with increasing KSS. The same variables were also significantly correlated with KSS, with a mean value for lapses (r=0.56). CONCLUSIONS: The KSS was closely related to EEG and behavioral variables, indicating a high validity in measuring sleepiness. SIGNIFICANCE: KSS ratings may be a useful proxy for EEG or behavioral indicators of sleepiness.  相似文献   
6.
We present a case of intrapulmonary metastasis developing 18 years after complete resection of thymoma. An 8 mm nodule in the lower lobe of the left lung was noted on chest X-ray in a 76-year-old woman who had undergone complete resection of Masaoka’s stage II thymoma 18 years earlier. Since the nodule grew to 17 mm during a 2-year follow-up, wedge resection was performed. The lesion was histologically diagnosed as an intrapulmonary metastasis from thymoma. Extremely late recurrence after complete resection of thymoma is discussed.  相似文献   
7.
Anthocyanins, which are responsible for a variety of bright colors (including red, blue, and purple) in fruits, vegetables, and flowers, are consumed as dietary polyphenols. Anthocyanin-containing fruits are thought to decrease coronary heart disease and are used in anti-diabetic preparations. Diabetes is associated with a variety of cardiovascular complications that may be mediated by endothelial dysfunction, and so this study was designed mainly to characterize the influence of a synthesized anthocyanidin derivative (HK-008) over acetylcholine (ACh)-induced relaxation in mesenteric arterial beds isolated from rats. In a glucose-tolerance test in intact rats, HK-008 (30 mg/kg) reduced the glucose level as effectively as the same dose of glibenclamide. The aortic relaxation induced by pinacidil (an ATP-sensitive potassium channel opener) was greatly inhibited by glibenclamide (10 microM), and also significantly inhibited by HK-008 (10 microM). Interestingly, the ACh-induced relaxation in the perfused, preconstricted mesenteric arterial bed was significantly enhanced by HK-008 (10 microM), and this enhancement was significantly attenuated by indomethacin (10 microM). The ACh-induced mesenteric relaxation was impaired by an increase in oxidative stress, viz. superoxide-generating treatment [xanthine oxidase (XO; 0.1 U/ml) plus hypoxanthine (HX; 10 microM)]. However, this impairment was strongly suppressed by HK-008 (10 microM). These results suggest that HK-008 increases endothelium-induced relaxation by suppressing oxidative stress or modulating prostanoids signaling. This compound may therefore be useful against certain cardiovascular disorders.  相似文献   
8.
To investigate the role of cell-mediated immunity (CMI) in glomerulonephritis (GN), we identified the infiltrating immune cells both within the glomerulus and in the interstitium. Frozen sections from 103 patients with various forms of GN: 10 with minor glomerular abnormality (MGA) as control, 10 with minimal change nephrotic syndrome (MCNS), 10 with membranous nephropathy (MN), 9 with focal glomerulosclerosis (FGS), 30 with IgA nephropathy (IgAN), 22 with acute post streptococcal glomerulonephritis (APSGN), and 2 with rapidly progressive glomerulonephritis (RPGN) were examined using monoclonal antibodies (MoAb) by indirect immunoalkaline-phosphatase labelling. In most glomerulonephritis, monocyte/M phi and helper/inducer T cells were predominantly infiltrating in the interstitium, but intraglomerular infiltration was rare, except for APSGN. This interstitial infiltration increased proportionally to the level of serum creatinine, and was most prominent in RPGN. Apparently different distribution was seen in APSGN, that is, prominent increase in total number of intra-glomerular monocyte/M phi infiltration with slightly increased T cells. The change was correlated with time after onset; namely the more leucocytic infiltration was observed when the tissue was taken earlier. These data suggest that in APSGN, monocyte/M phi accumulate in glomeruli via cell mediated immunity in addition to humoral immune mechanism resulting in glomerular hypercellularity, whereas in most chronic glomerulonephritis interstitial leucocyte infiltration, particularly helper T cells and monocyte/M phi may play an important role in the progression of glomerulonephritis.  相似文献   
9.
The effects of FUT-187 (6-amidino-2-naphthyl 4-[(4,5-dihydro-1H-imidazol-2-yl)amino]benzoate dimethanesulfonate, CAS 103926-82-5), a novel synthetic protease inhibitor, were examined in experimental rat and canine models of pancreatitis. 1. FUT-187 significantly increased the survival of rats with trypsin- and phospholipase A2-induced pancreatitis in a dose-dependent manner (10-100 mg/kg, p.o.). 2. FUT-187 decreased plasma enzymatic activity reflecting the degree of pancreatitis in rats with ethionine-induced pancreatitis, and showed a tendency to ameliorate histopathological changes in the pancreas (10-100 mg/kg p.o.). 3. FUT-187 (10 mg/kg) produced an obvious improvement of various biochemical parameters of pancreatitis and also reduced histopathological changes in the pancreas in animals with experimental pancreatitis produced by the closed duodenal loop method. In addition, FUT-187 significantly increased the survival of dogs when given by direct administration into the lumen of the closed duodenal loop. The therapeutic effects of FUT-187 in experimental pancreatitis were nearly equal in most instances to those of camostat mesilate. Thus, FUT-187 would appear to be an effective new agent for the treatment of pancreatitis.  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