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   1534篇
  免费   76篇
  国内免费   13篇
耳鼻咽喉   14篇
儿科学   56篇
妇产科学   44篇
基础医学   212篇
口腔科学   24篇
临床医学   96篇
内科学   420篇
皮肤病学   23篇
神经病学   178篇
特种医学   58篇
外科学   223篇
综合类   9篇
预防医学   34篇
眼科学   17篇
药学   97篇
中国医学   2篇
肿瘤学   116篇
  2023年   9篇
  2022年   29篇
  2021年   35篇
  2020年   19篇
  2019年   34篇
  2018年   29篇
  2017年   20篇
  2016年   36篇
  2015年   30篇
  2014年   39篇
  2013年   73篇
  2012年   88篇
  2011年   108篇
  2010年   60篇
  2009年   53篇
  2008年   77篇
  2007年   105篇
  2006年   93篇
  2005年   122篇
  2004年   103篇
  2003年   126篇
  2002年   117篇
  2001年   19篇
  2000年   13篇
  1999年   19篇
  1998年   23篇
  1997年   25篇
  1996年   21篇
  1995年   11篇
  1994年   8篇
  1993年   9篇
  1992年   5篇
  1991年   5篇
  1990年   5篇
  1989年   7篇
  1987年   3篇
  1986年   10篇
  1985年   4篇
  1984年   4篇
  1983年   4篇
  1982年   5篇
  1981年   4篇
  1980年   1篇
  1979年   2篇
  1978年   2篇
  1977年   2篇
  1976年   2篇
  1975年   1篇
  1967年   1篇
  1948年   1篇
排序方式: 共有1623条查询结果,搜索用时 15 毫秒
201.
Abstract: The Endoscopic resection of gastric tumors following local injections of hypertonic saline-epinephrine solution (ERHSE) was performed on 72 lesions (69 patients) of gastric tumors at Yoyogi Hospital etc. from March, 1983, to December, 1989. These included 40 cases of adenoma, 31 cases of carcinoma, and one carcinoid tumor. The average length of the major axis of the endoscopically resected tumors was 12 ± 9 mm. The curative rate at the first attempt was 94% (64 of 68 lesions). The curative rate of the final procedure was 99% (67 of 68 lesions). This excluded 4 lesions in 3 patients in whom a follow-up examination was not possible. There was no relationship found between the final cure rate and the form and location of the lesions. Fifty four lesions were resected with one session of snare cautery; the average length of their major axis was 9 ± 6mm. The resection of 18 lesions was done piecemeal, and the average length of their major axis was 20 ± 10mm. A statistical significance was noted between the size of the lesions which could be resected with one session of snare cautery and those treated by the piecemeal method, but no difference was noted in the location of lesions for the two groups. The indication for ERHSE was assessed in accordance with the cases that resulted in piecemeal resection, those in which the first ERHSE left residual tumor tissues, and those with perforation. ERHSE could be performed with difficulty on lesions which were (1) on the sharply bending gasric wall, (2) observed only tangentially, (3) inadequately observed. These lesions were situated on the gastric fornix, cardia, and their vicinities, the gastric angulus, posterior wall and greater curvature of the gastric body, and anterior wall and lesser curvature of the middle to the upper gastric body.  相似文献   
202.
In vitro assays revealed that COX-2 inhibitors with CA II inhibitory potency suppressed both differentiation and activity of osteoclasts, whereas that without the potency reduced only osteoclast differentiation. However, all COX-2 inhibitors similarly suppressed bone destruction in adjuvant-induced arthritic rats, indicating that suppression of osteoclast differentiation is more effective than that of osteoclast activity for the treatment. INTRODUCTION: Cyclooxygenase (COX)-2 and carbonic anhydrase II (CA II) are known to play important roles in the differentiation of osteoclasts and the activity of mature osteoclasts, respectively. Because several COX-2 selective agents were recently found to possess an inhibitory potency against CA II, this study compared the bone sparing effects of COX-2 selective agents with and without the CA II inhibitory potency. MATERIALS AND METHODS: Osteoclast differentiation was determined by the mouse co-culture system of osteoblasts and bone marrow cells, and mature osteoclast activity was measured by the pit area on a dentine slice resorbed by osteoclasts generated and isolated from bone marrow cells. In vivo effects on arthritic bone destruction were determined by radiological and histological analyses of hind-paws of adjuvant-induced arthritic (AIA) rats. RESULTS: CA II was expressed predominantly in mature osteoclasts, but not in the precursors. CA II activity was inhibited by sulfonamide-type COX-2 selective agents celecoxib and JTE-522 similarly to a CA II inhibitor acetazolamide, but not by a methylsulfone-type COX-2 inhibitor rofecoxib. In vitro assays clearly revealed that celecoxib and JTE-522 suppressed both differentiation and activity of osteoclasts, whereas rofecoxib and acetazolamide suppressed only osteoclast differentiation and activation, respectively. However, bone destruction in AIA rats was potently and similarly suppressed by all COX-2 selective agents whether with or without CA II inhibitory potency, although only moderately by acetazolamide. CONCLUSIONS: Suppression of osteoclast differentiation by COX-2 inhibition is more effective than suppression of mature osteoclast activity by CA II inhibition for the treatment of arthritic bone destruction.  相似文献   
203.
成熟、有活性的树突状细胞 (DCs)对于活化的肿瘤特异性淋巴细胞在致癌过程中的再生和存活是至关重要的。肝细胞癌 (HCC)和肝硬化 (LC)患者的外周血中CD83阳性的DCs的浓度几乎是相同的。就肝组织而言 ,与LC相比 [(6 6± 10 9)比 (33 3± 2 4 )个DCs 组织切片 ,P <0 0 5 ) ],HCC中的CD83阳性的DCs却明显减少。更重要的是 ,HCC癌结节中完全缺乏CD83阳性的DCs。本研究初步探讨了在HCC的发病机制中肝内浸润的有活性的DCs的作用  相似文献   
204.
Estradiol benzoate administered to ovariectomized female rats significantly elevated the mean spontaneous firing rate and frequency of successful antidromic propagation into the somatodendritic spike and significantly reduced the strength of post-stimulus inhibition in presumed A1 noradrenergic neurons projecting directly to the preoptic and anterior hypothalamic area. The occurrence of both antidromic spikes and post-stimulus inhibition of the majority of these neurons was completely abolished by the injection of 6-hydroxydopamine but not by 5, 7-dihydroxytryptamine directly into the medial forebrain bundle.  相似文献   
205.
Seventeen neurons in the subfornical organ (SFO) were antidromically activated by electrical stimulation of the paraventricular nucleus (PVN) in the rat. The activity of all identified SFO neurons was excited by microiontophoretically (MIPh) applied angiotensin II (AII) and the effect of AII was blocked by MIPh-applied saralasin (Sar), an AII antagonist, but not by atropine (Atr), a muscarinic antagonist. In these identified SFO neurons, 9 were also excited and 8 were not affected by MIPh-applied acetylcholine (ACh) and the effect of ACh was attenuated by not only MIPh-applied Atr but also by Sar. These results suggest that there are specific AII- and both AII- and ACh-sensitive types of SFO neurons with efferent projections to the PVN.  相似文献   
206.
Electrical stimulation of the rat A1 noradrenergic region produced excitation (77%) of the activity of putative vasopressin (VP)-secreting neurons in the paraventricular nucleus (PVN) and produced excitation (4%), inhibition (26%) and excitation-inhibition (11%) of the activity of PVN neurons that were not antidromically identified by neurohypophysial stimulation. The excitatory response of putative VP-secreting neurons was blocked by microiontophoretically applied phentolamine, an α-adrenoceptor antagonist, but not by timolol, a β-adrenoceptor antagonist. The inhibitory response of unidentified PVN neurons, on the other hand, was blocked by timolol, but not by phentolamine.  相似文献   
207.
Abstract: The Nikkiso HPM-15 is a minimally sized centrifugal pump. Preliminary results regarding clinical use of this pump for cardiopulmonary bypass (CPB) procedures have been reported previously. Recently, we have managed some additional cases using a newly developed controller. This article reports our clinical experiences with the use of this pump. We have managed 23 cases with a Nikkiso centrifugal pump. Twenty-two patients underwent CPB and 1 patient with fulminant viral myocarditis underwent percutaneous cardiopulmonary support (PCPS). With this pump, the circuit was extremely easy to prepare and deaeration was achieved readily. Hemodynamics during CPB and PCPS were stable in all cases. The increase in serum-free hemoglobin levels during CPB with this pump was as low as that seen in preliminary tests. A decrease in the platelet count was observed after the initiation of CPB with this pump; however, platelet counts returned to preoperative values 7 days after surgery. Moreover, urine output during CPB with this pump was as high as that seen in preliminary tests. No abnormalities in renal or liver function occurred during CPB. It appears that this new centrifugal pump is safe and easy to operate, and we conclude that it is useful for CPB and PCPS.  相似文献   
208.
We directly measured aortic depressor nerve activity (ADNA) in rabbits to investigate changes in arterial baroreceptor afferent activity (ABAA) in response to nonpulsatile systemic circulation (NC) during total left heart bypass (TLHB). ADNA was measured before and 5, 20, 30, 40, 50, and 60 min after the start of TLHB while maintaining the mean aortic pressure (MAP) at preestablished values (n = 10). At 5 min, the ADNA was significantly increased compared to its baseline value. At 30 min, it was significantly decreased compared to its value at 5 min and thereafter remained the same. The ADNA was then measured before and 5 and 30 min after the start of TLHB under increased MAP (n = 10). The results showed that the percentage changes in ADNA during TLHB were significantly less than that observed when the MAP was increased before TLHB. We conclude that ABAA acutely adapts to NC 30 min after its initiation, but changes in ABAA are depressed under NC combined with increased MAP.  相似文献   
209.
An 8-month-old Japanese girl with cyanosis and evidence of a round shadow connected with the right cardiac border on the chest X-ray film was diagnosed as a case of direct communication of the right pulmonary artery with the left atrium (RPA-LA communication) following cardiac catheterization and angiocardiography. She had a history of transient congestive heart failure in the early neonatal period. A secundum atrial septal defect and a two-lobed right lung were also present. The patient became asymptomatic after a successful ligation of the anomalous connecting vessel.  相似文献   
210.
Natural seeds of Japanese horse chestnut (Aesculus turbinata Blume) contain large amounts of mixed triterpenoidal saponins called escins. Recent studies have shown that escins have several biological activities including anti-inflammatory action and inhibitory effects on the absorption of ethanol and glucose. For the edible utilization of the seeds, natural seeds are usually treated with wooden ashes to remove harshness. Here, we found the novel compounds derived from escins in the edible seeds after the food processing with wooden ashes. The instrumental analyses revealed the chemical structures of escins and the derivatives. These compounds are identified as four types of deacetylescins Ia, IIa, Ib, and IIb as well as two types of desacylescins I and II. To determine their biological activity, the purified compounds were tested for their potential nutraceutical activity. The oral glucose tolerance test in mice revealed that a single oral administration of the isolated components of deacetylescins at a dose of 100 mg/kg was clearly effective in attenuating the elevation of blood glucose levels. The inhibitory effects of escins and their derivatives were in the order of escins > deacetylescins > desacylescins. Moreover, we found the inhibitory activity of those compounds on pancreatic lipase. Escins were the most potent in inhibiting the enzyme activity, and followed by desacylescins and then deacetylescins. Taken together, our results suggest the potential usefulness of novel saponins including deacetylescins and desacylescins from edible seeds as novel sources for nutraceutical foods with anti-obese effects.  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