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   7724篇
  免费   329篇
  国内免费   21篇
耳鼻咽喉   28篇
儿科学   127篇
妇产科学   104篇
基础医学   870篇
口腔科学   242篇
临床医学   539篇
内科学   1940篇
皮肤病学   108篇
神经病学   636篇
特种医学   407篇
外国民族医学   1篇
外科学   1588篇
综合类   34篇
预防医学   223篇
眼科学   129篇
药学   477篇
中国医学   9篇
肿瘤学   612篇
  2023年   49篇
  2022年   76篇
  2021年   147篇
  2020年   71篇
  2019年   114篇
  2018年   134篇
  2017年   109篇
  2016年   109篇
  2015年   131篇
  2014年   174篇
  2013年   182篇
  2012年   328篇
  2011年   318篇
  2010年   191篇
  2009年   171篇
  2008年   333篇
  2007年   308篇
  2006年   325篇
  2005年   338篇
  2004年   313篇
  2003年   309篇
  2002年   331篇
  2001年   245篇
  2000年   248篇
  1999年   222篇
  1998年   94篇
  1997年   80篇
  1996年   55篇
  1995年   54篇
  1994年   54篇
  1993年   48篇
  1992年   186篇
  1991年   210篇
  1990年   195篇
  1989年   175篇
  1988年   167篇
  1987年   171篇
  1986年   137篇
  1985年   142篇
  1984年   115篇
  1983年   102篇
  1982年   50篇
  1979年   81篇
  1978年   52篇
  1975年   51篇
  1971年   49篇
  1969年   53篇
  1968年   53篇
  1967年   42篇
  1966年   52篇
排序方式: 共有8074条查询结果,搜索用时 0 毫秒
141.
BACKGROUND: Recent clinical trials suggest that the mortality in high-risk patients with ischemic heart disease can be significantly reduced with the use of implantable cardioverter-defibrillator (ICD). Given the high cost and invasiveness of the procedure, it is important to apply it to the patients after myocardial infarction (MI) highly susceptible to sudden arrhythmic death. OBJECTIVE: The purpose of this study was to assess clinical predictors of mortality in post-MI patients in Japan. METHODS AND RESULTS: In 495 consecutive MI survivors, 350 (71%) received acute-reperfusion therapy, whereas 145 (29%) did not. Nonsustained ventricular tachycardia (NSVT) was present in 136 patients (28%) in 24-h ambulatory ECGs at 7+/-6 in-hospital days. Left ventricular dysfunction (LVEF< or =35%) was present in 20/347 patients (5.7%) at 13+/-8 days. Forty-eight patients (9.7%) died during the follow-up period (48+/-13 months); 23 from cardiac and 25 from noncardiac causes. Kaplan-Meier survival analyses showed that mortality rates were higher among patients who were > or =70 years old (log-rank test, P<0.0001); had heart failure at admission (Killip scale> or =2, P=0.001); did not receive acute-reperfusion (P=0.004); and had left ventricular dysfunction with LVEF< or =35% (P=0.02). The presence of NSVT was a significant predictor of death (P=0.036) only in the patients who did not receive acute-reperfusion. Multivariate Cox regression analysis revealed that an independent predictor of total mortality was an age> or =70 (odds ratio, 1.06; 95% confidence interval, 1.01-1.11; P<0.00001). CONCLUSIONS: High-risk patients after acute MI can be identified on the basis of age, ventricular dysfunction, heart failure and acute-reperfusion therapy. The presence of NSVT before discharge has a prognostic value only in the patients without acute-reperfusion.  相似文献   
142.
143.
To estimate the number of patients with intractable respiratory diseases, we conducted a two-stage nationwide epidemiological survey in 1997. The first survey was performed at randomly sampled hospitals to identify the number of patients treated. The second survey sought detailed clinico-epidemiological data on the patients reported in the first survey. The response rates were 54% for the first survey and 62% for the second. Based on the survey findings, we derived the following nationwide estimates: 450 patients (95% confidence interval: 360-530) with chronic thromboembolic pulmonary hypertension; 230 (200-260) with primary pulmonary hypertension; 180 (150-210) with obesity-associated hypoventilation syndrome; 40 (30-50) with primary alveolar hypoventilation syndrome; 160 (140-180) with histiocytosis X; and 190 (150-230) with juvenile pulmonary emphysema.  相似文献   
144.
145.
Distribution and quantification of PRL in the pituitary gland of the frog Rana ridibunda were investigated using a high-affinity antiserum raised against bullfrog prolactin (PRL). The immunoreactive PRL-producing cells were distributed throughout the pars distalis, the highest density of cells being observed in the rostral region of the adenohypophysis facing the neurointermediate lobe. The dorsal region of the pars distalis contained only a few scattered PRL-immunoreactive cells. At the electron microscopic level, PRL-containing cells were visualized using the immunogold procedure. PRL-immunoreactive material was exclusively stored in secretory granules (size ranging from 200 to 700 nm in diameter). Neither the rough endoplasmic reticulum nor the Golgi apparatus were immunolabeled. Using a radioimmunoassay method we have compared the displacement curves obtained with bullfrog PRL and acetic extracts from Rana ridibunda pituitary. The two binding curves were not completely parallel, suggesting the existence of slight variations of the amino acid sequences of PRL in the two species. The concentration of PRL in the green frog adenohypophysis appeared somewhat higher (35.3 +/- 8.8 micrograms/mg protein) than that in the bullfrog pituitary. These results validate the use of an antiserum to bullfrog PRL to investigate the regulation of PRL secretion in Rana ridibunda.  相似文献   
146.
OBJECTIVES: Frequency occurrence of nonacidic and nonliquid reflux events in the pharynx has not been systematically studied. The aim of the present study was to characterize the physical (liquid, gas, and mixed gas/liquid) and pH properties of the gastroesophagopharyngeal refluxate. METHODS: We performed a total of 31 24-h simultaneous ambulatory pharyngoesophageal impedance and pH recordings in 11 GERD patients, 10 patients with reflux-attributed laryngitis, and 10 healthy controls. RESULTS: On average, the total number of reflux events (all kinds) in the pharynx was less than half of that in the proximal esophagus (18 +/- 4 vs 50 +/- 4, p < 0.01). Most of the pharyngeal reflux events were gas events and were observed in all three studied groups. Prevalence of these gas reflux events ranged between 0 and 74. The number of gas reflux events accompanied by a minor pH drop in laryngitis patients (1 (0-36)) was significantly higher than those in GERD and controls (0 (0-2) and 0 (0-1), respectively, p < 0.05). There was no significant difference in the number of nonacidic gas reflux events among the three groups (GERD: 10 (2-57), laryngitis: 11.5 (0-51), controls: 10.5 (0-27)). Impedance recording identified a total number of 566 events in the pharynx. Of these, a total of 563 events were compatible with gas reflux events, 101 events were accompanied by minor drops in intrapharyngeal pH, whereas 460 events were not accompanied by any pharyngeal pH change. CONCLUSIONS: Concurrent impedance and pH recordings detect significantly more events qualifying as reflux in the pharynx than pH recordings alone. A substantial majority of these events are gaseous refluxes both with and without minor pH drops. Gas reflux events with weak acidity appear to be more common among patients with reflux-attributed laryngeal lesions compared to GERD patients and controls.  相似文献   
147.
BACKGROUND: Hypersensitivity reactions to fish are a common food allergy, but IgE-binding activity to fish species have not been fully elucidated. The aim of this study was to identify fish with high binding activity to IgE in sera from Japanese fish-hypersensitive individuals. METHODS: 38 children with a history of at least one episode of hypersensitivity after ingestion of fish were enrolled and 34 children with no history of reactions and negative IgE results for at least five kinds of fish antigen were included as controls. Using a radioallergosorbent test, we examined IgE-binding to each fish species using sera from fish-hypersensitive subjects. Fish were then graded according to IgE-binding activity. RESULTS: Many fish species, including red salmon, silver salmon, yellowfin tuna, big eyed tuna, Atlantic tuna, saurel, skipper, yellowtail, Japanese sardine, bonita and mackerel had high IgE-binding activity. All of these fish are abundantly consumed in Japan. The hypersensitivity reactions experienced by many subjects occurred after ingestion of species with high IgE-binding activity. Only halibut (Osteichthyes) and sharks (Chondrichthyes) had low IgE-binding activity. CONCLUSIONS: A correlation was observed between IgE levels and expression of symptoms after fish ingestion. High consumption of salmon, tuna, scad (including saurel), skipper, yellowtail, sardine, bonita and mackerel in Japan might be the cause of the high IgE-binding activity of these species. The grades of fish species consumed widely in Japan are likely to be useful for nutritional instruction of fish-allergic patients.  相似文献   
148.
Ventricular septal rupture is a serious complication of acute myocardial infarction. We experienced a case of septal rupture immediately after primary angioplasty with thrombolysis, whose angiographic findings were similar to those of coronary perforation. The progression of septal rupture was delineated by the serial angiograms. Catheter Cardiovasc Interv 2004;62:466–470. © 2004 Wiley‐Liss, Inc.  相似文献   
149.
The cell-cycle status of hematopoietic stem and progenitor cells (HSPCs) becomes activated following chemotherapy-induced stress, promoting bone marrow (BM) regeneration; however, the underlying molecular mechanism remains elusive. Here we show that BM-resident group 2 innate lymphoid cells (ILC2s) support the recovery of HSPCs from 5-fluorouracil (5-FU)–induced stress by secreting granulocyte-macrophage colony-stimulating factor (GM-CSF). Mechanistically, IL-33 released from chemo-sensitive B cell progenitors activates MyD88-mediated secretion of GM-CSF in ILC2, suggesting the existence of a B cell–ILC2 axis for maintaining hematopoietic homeostasis. GM-CSF knockout mice treated with 5-FU showed severe loss of myeloid lineage cells, causing lethality, which was rescued by transferring BM ILC2s from wild-type mice. Further, the adoptive transfer of ILC2s to 5-FU–treated mice accelerates hematopoietic recovery, while the reduction of ILC2s results in the opposite effect. Thus, ILC2s may function by “sensing” the damaged BM spaces and subsequently support hematopoietic recovery under stress conditions.  相似文献   
150.
It is often difficult to predict the response to telaprevir-pegylated interferon (PEG-IFN)-ribavirin triple therapy and the appearance of telaprevir-resistant variants. The present study determined the predictive factors of a sustained virological response (SVR) to 12- or 24-week triple therapy (T12PR12 or T12PR24, respectively) in 194 Japanese patients infected with hepatitis C virus genotype 1b (HCV-1b). The study also evaluated whether ultradeep sequencing technology can predict at baseline the emergence of resistant variants after the start of therapy. Analysis of the data of the entire group indicated that an SVR was achieved in 78% of the patients. Multivariate analysis identified IL28B rs8099917 (genotype TT), the substitution of amino acid (aa) 70 (Arg70), response to prior treatment (naive or relapse), PEG-IFN dose (≥1.3 μg/kg of body weight), and treatment regimen (T12PR24) as significant determinants of SVR. Among patients of the T12PR24 group, 92% with genotype TT achieved an SVR, irrespective of a substitution at aa 70. In patients with the non-TT genotype, an SVR was achieved in 76% of those with Arg70, while only 14% of patients with the non-TT genotype, Gln70(His70), and nonresponse to ribavirin combination therapy achieved an SVR. Ultradeep sequencing was conducted for 17 patients who did not achieve an SVR to determine the emergence of resistant variants during therapy. De novo resistant variants were detected in 16 of 17 patients (94%), regardless of the variant frequencies detected at baseline. In conclusion, the results indicate that the response to triple therapy can be predicted by the combination of host, viral, and treatment factors and that it is difficult to predict at baseline the telaprevir-resistant variants that emerge during triple therapy, even with the use of ultradeep sequencing.  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