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   2367篇
  免费   89篇
  国内免费   7篇
耳鼻咽喉   18篇
儿科学   60篇
妇产科学   7篇
基础医学   380篇
口腔科学   65篇
临床医学   175篇
内科学   607篇
皮肤病学   15篇
神经病学   205篇
特种医学   50篇
外科学   333篇
综合类   8篇
一般理论   1篇
预防医学   64篇
眼科学   118篇
药学   172篇
中国医学   13篇
肿瘤学   172篇
  2022年   10篇
  2021年   17篇
  2020年   10篇
  2019年   16篇
  2018年   15篇
  2017年   22篇
  2016年   31篇
  2015年   28篇
  2014年   44篇
  2013年   30篇
  2012年   93篇
  2011年   138篇
  2010年   62篇
  2009年   67篇
  2008年   150篇
  2007年   163篇
  2006年   201篇
  2005年   168篇
  2004年   180篇
  2003年   178篇
  2002年   190篇
  2001年   25篇
  2000年   19篇
  1999年   32篇
  1998年   40篇
  1997年   33篇
  1996年   26篇
  1995年   32篇
  1994年   46篇
  1993年   30篇
  1992年   23篇
  1991年   22篇
  1990年   24篇
  1989年   30篇
  1988年   25篇
  1987年   22篇
  1986年   20篇
  1985年   8篇
  1984年   19篇
  1983年   17篇
  1982年   19篇
  1981年   17篇
  1980年   13篇
  1979年   11篇
  1978年   18篇
  1977年   8篇
  1976年   7篇
  1975年   8篇
  1974年   6篇
  1973年   8篇
排序方式: 共有2463条查询结果,搜索用时 15 毫秒
141.
We aimed to assess the utility of a newly developed automated urinary flow cytometer (UFCM) in differentiating the origin of hematuria in the mass screening system for renal diseases in school children. In total, 4,620 children aged 6–14 years with abnormal urinary findings by the screening program in Tokyo were enrolled. Tentative diagnoses were made based on the criteria for this screening program: nephritis in 11, suspected nephritis in 104, hematuria in 771, minimal hematuria in 1,506, proteinuria in 477, urinary tract infection in 83, and healthy in 1,668. Glomerular hematuria, assessed by UFCM, was found in 81.8% of nephritis, 58.7% of suspected nephritis, 59.7% of hematuria, 57.4% of minimal hematuria, 13.4% of proteinuria, and 21.5% of the healthy group. The presence of glomerular hematuria assessed by UFCM had a sensitivity of 61.0%, specificity of 78.5%, positive predictive value of 16.3%, and negative predictive value of 96.7% for the diagnosis of nephritis and suspected nephritis. Thus, our results imply that the absence of glomerular hematuria as assessed by UFCM is highly predictive of the absence of nephritis. If healthy children with non-glomerular hematuria by UFCM could be excluded, the total annual cost saving would be approximately 147.4 million JPY, which is equivalent to 5.2% of the current system. In conclusion, a simple, automated and rapid test for glomerular hematuria using UFCM is useful for mass screening. It can precisely predict children with only transient hematuria who do not have any serious illness, and therefore can exclude further unnecessary examinations, resulting in the improvement of cost-effectiveness of the current program.  相似文献   
142.
We report a case of pancreatic injury, caused by a stab wound, in which ductal injury and wound depth were clearly identified by intraoperative ultrasonography. A 65-year-old woman was emergently admitted to our hospital after stabbing herself in the abdomen in a suicide attempt. Preoperative computed tomography (CT) and laboratory examination revealed liver and pancreatic injury with massive abdominal bleeding and free air. Operative findings included injuries of the stomach, small bowel, colon, liver, and pancreas. The pancreatic lacerations were 1cm in length, in the body. Intraoperative ultrasonography enabled the diagnosis of a lacerated main pancreatic duct with no damage to the major vessels posterior to the pancreas. Distal pancreatectomy; simple repairs of the liver, small bowel, and stomach; exteriorization of the injured colon; cholecystostomy; gastrostomy; and jejunostomy were performed. The patient recovered and was transferred to a psychiatric hospital 87 days after surgery. In this patient, intraoperative ultrasonography was successfully used to identify the degree of injury to the pancreatic duct, as well as the depth of the stab wound. In conclusion, intraoperative ultrasonography should be routinely performed to detect main pancreatic duct injury in penetrating pancreatic trauma.  相似文献   
143.
We previously showed that alpha-eleostearic acid (alpha-ESA; 9Z11E13E-18:3) is converted to conjugated linoleic acid (CLA; 9,11-18:2) in the liver and plasma of rats that were given diets including 1% alpha-ESA for 4 wk. In this study, we investigated this phenomenon in detail. First, the chemical structure of CLA produced by alpha-ESA administration was determined. After alpha-ESA was orally administered to rats, CLA in rat liver was isolated by HPLC. The positional and geometric isomerism was determined using GC-EI/MS and (13)C-NMR, respectively, and the CLA generated in rats after alpha-ESA feeding was confirmed to be 9Z11E-CLA. Next, the concentrations of alpha-ESA and CLA were determined 0, 3, 6, and 24 h after oral administration of alpha-ESA to rats. Moreover, we also investigated whether enteric bacteria are involved in the conversion of alpha-ESA to CLA using germ-free rats. alpha-ESA was orally administered to germ-free and normal rats and alpha-ESA and CLA were detected in the organs of both groups. In addition, to confirm that this reaction was enzyme-mediated, alpha-ESA was reacted with tissue homogenates (liver, kidney, and small intestine mucous) and coenzymes (NADH, NAD(+), NADPH, and NADP(+)), and the enzyme activities were estimated from the amount of CLA produced. CLA was detected when alpha-ESA was reacted with liver, kidney, and small intestine mucous homogenates and a coenzyme (NADPH). These results indicated that alpha-ESA is converted to 9Z11E-CLA in rats by a Delta13-saturation reaction carried out by an NADPH-dependent enzyme.  相似文献   
144.
Both conjugated linoleic acid (CLA) and eicosapentaenoic acid (EPA) have an antitumor effect. Hence, we hypothesized that a combination of conjugated double bonds and an (n-3) highly unsaturated fatty acid would produce stronger bioactivity. To verify the antitumor effect of conjugated EPA (CEPA), we transplanted DLD-1 human colon tumor cells into nude mice, and compared the tumor growth between CEPA-fed mice and CLA- and EPA-fed mice. After tumor cell inoculation, mice were assigned to 1 of 4 groups (control, CLA, EPA, and CEPA) consisting of 10 mice each. The control group received only safflower oil fatty acids, whereas the remaining groups received a mixture of safflower oil fatty acids and 20 g/100 g of total fatty acids as CLA, EPA, or CEPA. Mice were fed once every 2 d for 4 wk at a dose of 50 mg/mouse at each feeding. After 4 wk, tumor growth in CEPA-fed mice was significantly suppressed, compared with that in CLA- (P < 0.005) and EPA-fed mice (P < 0.001). DNA fragmentation in the tumor tissues of the CEPA-fed mice occurred more frequently than in the CLA- (P < 0.001) and EPA-fed mice (P < 0.001), suggesting that CEPA induced apoptosis in the tumor tissues. To further investigate the mechanism, the level of oxidative stress in the tumor tissues was determined. The CEPA-fed mice showed significant lipid peroxidation, compared with the CLA- (P < 0.001) and EPA-fed mice (P < 0.001). Therefore, we verified that CEPA has a stronger in vivo antitumor effect than EPA and CLA, and that CEPA acts through induction of apoptosis via lipid peroxidation.  相似文献   
145.
Absorption of fluorescein isothiocyanate-labeled lysozyme (FITC-lysozyme) was examined in rat small intestine. Messenger RNA of megalin, an endocytic receptor for lysozyme in the kidney, was expressed in the lower but not in the upper intestine. In in situ closed loop and recirculation methods, absorption of FITC-lysozyme from the upper intestine was much higher than from the lower intestine. The absorption rate of FITC-lysozyme in the upper intestine was significantly higher than FITC-dextran and was inhibited by unlabeled lysozyme in a concentration-dependent manner. The absorption of FITC-lysozyme was also inhibited by spermine and phenylarsine oxide. These results indicate that the intestinal absorption of lysozyme is segment-selective and occurs preferentially from the upper intestine. Megalin expressed in the lower intestine appears not to have a significant role in the absorption of lysozyme. In the upper intestine, lysozyme appears to be absorbed by an endocytic pathway, and cationic charge may be important for lysozyme absorption.  相似文献   
146.
Rationale Sigma1 receptors (Sig-1R) are implicated in behavioral sensitization, conditioned place preference, and cellular restructuring induced by psychostimulants. We previously reported that rats which actively self-administered methamphetamine for 5 weeks and were then withdrawn from methamphetamine for 24 h showed downregulation of dopamine D2 autoreceptors (approximately 30%) in the midbrain and this was not seen in rats that passively received injections of methamphetamine or saline at the same time (yoked controls). Involvement of Sig-1R in the self-administration of psychostimulants, however, has never been reported.Objectives This study examined neuroadaptive changes in Sig-1R in the brains of rats self-administering methamphetamine.Methods Three groups of rats were tested simultaneously 5 days per week, for 5 weeks (25 daily sessions). Two groups served as yoked controls and passively received an injection of either 0.1 mg/kg methamphetamine or saline (not contingent on responding) each time a response-contingent injection of 0.1 mg/kg methamphetamine was actively self-administered by the first group of rats. Protein and mRNA levels of Sig-1R were then measured by Western and Northern blottings, respectively.Results There was a marked upregulation of Sig-1R proteins (50%) in the midbrain and altered levels of Sig-1R mRNA in the frontal cortex and hippocampus of rats that learned to actively self-administer methamphetamine, but not in yoked methamphetamine- or saline-control rats.Conclusions Neuroadaptive increases in Sig-1R seen in this study may contribute to the reinforcing effects of methamphetamine. This upregulation of Sig-1R may be mediated by increased protein kinase A activity due to downregulation of dopamine D2 autoreceptors.R.S., Z.J., T.H. and M.T. contributed equally to this work  相似文献   
147.
The human genome project has been completed, but the function of many genes is unknown. It is, therefore, necessary to elucidate the function of a large number of genes within a short time. To achieve this goal, materials are needed that condense or package DNA into nano-particles that can easily be taken up by cells and would allow DNA to be retained without degradation. Atelocollagen is a reliable carrier for gene delivery because it is considered safe and appropriate for practical use. We developed a basic technique for high-throughput gene transfer and expression screening by pre-coating a multi-well plate with an Atelocollagen/DNA complex in which cells are then seeded. Complexes with a nano-particle form were efficiently transduced into cells without the use of additional transfection reagents, and they allowed for long-term gene expression. The complex spotted onto the well of a plate was stable for a long period and allowed the cells to transduce and express reporter genes. We also showed that the present method with Atelocollagen-based gene transfer is applicable to gene medicines, such as antisense ODNs, siRNA, and adenovirus vectors. These results suggest that an Atelocollagen-based cell transfection array may be appropriate for general use in the high-throughput screening of large sets of gene medicines with functions in mammalian cells.  相似文献   
148.
We have previously shown that conjugated linolenic acids (CLnA) prepared by alkaline isomerization have a stronger antitumor effect than conjugated linoleic acids (CLA). In this study we have compared the suppressive effect on tumor growth of alpha-eleostearic acid (alpha-ESA, 9Z11E13E-18:3) with those of the CLA isomers 9Z11E-CLA and 10E12Z-CLA, using nude mice into which DLD-1 human colon cancer cells were transplanted. The results showed that alpha-ESA, which is a CLnA that can be prepared from natural sources in bulk, had a stronger antitumor effect than CLA. DNA fragmentation was enhanced and lipid peroxidation was increased in tumor tissues of the alpha-ESA-fed mice, which suggested that alpha-ESA induced apoptosis via lipid peroxidation. Furthermore, treatment of DLD-1 cells with alpha-ESA, 9Z11E-CLA and 10E12Z-CLA confirmed that alpha-ESA had a stronger antitumor effect than CLA in cultured cell lines. The induction of apoptosis by alpha-ESA was consistent with enhanced DNA fragmentation, increased caspase activity and increased expression of caspase mRNA following alpha-ESA treatment. Addition of alpha-tocopherol, an antioxidant, suppressed oxidative stress and apoptosis, suggesting that these effects were associated with lipid peroxidation.  相似文献   
149.
A structure-activity relationship of dopamine and 3-benzazepine derivatives is discussed, using theoretically calculated results. In order to clearly divide dopamines and 3-benzazepines into a strongly active and a weakly active group, the CC50, two different dipole moments (microESP-G and microESP-W) and heat of formation (deltaHf) of dopamine [1-13] and 3-benzazepine derivatives [14-23] were separately calculated in two states of gas-phase and water-solution by the COSMO/PM3 method. It was found that ten derivatives [1-3, 9, 12-13 and 20-23] (CC50: 0.056 to 2.5 mM) showed the strongest cytotoxic activity with small delta(deltaHf) values, whereas thirteen derivatives [4-8, 10-11, 14-19] (CC50: > 3.6 mM) showed the weakest cytotoxic activity with large delta(deltaHf) values.  相似文献   
150.
The present study was designed to investigate the effects of prophylactic antibiotic therapy and the cost-effectiveness of Cefazolin (CEZ) and Sulbactam/Ampicillin (SBT/ABPC) in gastric cancer surgery employing clinical pathway. 157 patients (62 in the CEZ group and 95 in the SBT/ABPC group), who underwent surgery for gastric cancer at the First Department of Surgery of our hospital, were investigated. There was no significant difference between the groups with regard to sex, age, incidence of complication, stage of cancer, surgical method, operative time and blood loss, length of hospitalization, the appearance of systemic inflammatory response syndrome (SIRS), changes body temperature, white blood cell count (WBC), C-reactive protein (CRP), or clinical outcome of postoperative care by a nurse during post-operation for 7 days. The prophylactic effect of infection was also no different between the CEZ (69.4%) and SBT/ABPC (69.5%) groups. In contrast, decision analysis strongly indicated that the anticipate cost of antibiotics was higher in the latter group (yen 20402) than in the CEZ group (yen 15556), suggesting that the prophylactic effect of CEZ may be more cost-effective. Thus, evaluations of pharmacotherapy from the aspect of cost may be one of the important responsibility of hospital pharmacists in the future.  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