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   9237篇
  免费   326篇
  国内免费   37篇
耳鼻咽喉   107篇
儿科学   222篇
妇产科学   88篇
基础医学   1125篇
口腔科学   312篇
临床医学   554篇
内科学   2222篇
皮肤病学   148篇
神经病学   668篇
特种医学   459篇
外科学   1706篇
综合类   32篇
预防医学   166篇
眼科学   134篇
药学   479篇
中国医学   17篇
肿瘤学   1161篇
  2023年   42篇
  2022年   79篇
  2021年   131篇
  2020年   78篇
  2019年   125篇
  2018年   162篇
  2017年   157篇
  2016年   183篇
  2015年   170篇
  2014年   254篇
  2013年   309篇
  2012年   504篇
  2011年   590篇
  2010年   339篇
  2009年   356篇
  2008年   548篇
  2007年   598篇
  2006年   611篇
  2005年   603篇
  2004年   634篇
  2003年   593篇
  2002年   575篇
  2001年   79篇
  2000年   85篇
  1999年   133篇
  1998年   166篇
  1997年   153篇
  1996年   151篇
  1995年   113篇
  1994年   119篇
  1993年   121篇
  1992年   62篇
  1991年   64篇
  1990年   59篇
  1989年   53篇
  1988年   46篇
  1987年   41篇
  1986年   46篇
  1985年   36篇
  1984年   47篇
  1983年   46篇
  1982年   43篇
  1981年   42篇
  1980年   32篇
  1979年   19篇
  1978年   29篇
  1977年   17篇
  1976年   16篇
  1974年   17篇
  1973年   15篇
排序方式: 共有9600条查询结果,搜索用时 15 毫秒
31.
32.
33.
34.
Alpha2-macroglobulin is a protease inhibitor that enhances procoagulant properties via the neutralization of plasmin, plasminogen activators and metalloproteinases. Additionally, alpha2-macroglobulin is thought to be involved in inflammatory reactions as a carrier protein for interleukin-6 (IL-6). The objective of this study was to evaluate the usefulness of alpha2-macroglobulin as a biomarker for cerebrovascular diseases. Patients with acute ischemic stroke (n = 159; 93 male and 66 female, 71.6 ± 10.3 years) and patients with no previous history of stroke (n = 77; 38 male and 39 female, 70.7 ± 9.5 years) were consecutively enrolled in this study. White matter lesions were assessed via the fluid-attenuated inversion recovery image of magnetic resonance images using the Fazekas classification. The serum alpha2-macroglobulin levels were measured by nephelometry. The serum alpha2-macroglobulin levels at admission in patients with acute ischemic stroke were higher than those in the control patients (230.2 ± 73.7 vs. 205.0 ± 55.8 mg/dl, p = 0.009). The serum alpha2-macroglobulin levels were positively correlated with age and the severity of the white matter lesions (R 2 = 0.048, p < 0.001 and R 2 = 0.058, p < 0.001, respectively), although there was no significant association between serum alpha2-macroglobulin levels and IL-6 levels. In addition, multivariate analysis showed that increased serum alpha2-macroglobulin levels were independently associated with the severity of white matter lesions [standardized partial regression coefficient (β) 0.102, p = 0.026]. Increased serum alpha2-macroglobulin levels might be involved in the pathophysiology of acute ischemic stroke. Furthermore, serum alpha2-macroglobulin levels, which were associated with high-grade white matter lesions, may reflect the chronic pathophysiological condition of cerebral small vessel disease.  相似文献   
35.
More and more studies on the frequency of autism spectrum disorders (ASD) have been published recently, most of which show the increase in prevalence data. In this review, the author pointed out factors and parameters to be considered in analyzing frequency data, i.e., the enlargement of the concept of autism, prevalence and incidence, accuracy and precision in the initial screening, and the effect of the “vaccine debate”. The proportion of high-functioning ASD has been growing higher and higher due to better recognition in the last few years, and the apparent increase might still be the tip of an iceberg. Future epidemiological studies should include themes on diversity of the longitudinal course and re-conceptualization of ASD by dimensional diagnosis.  相似文献   
36.
The diagnosis of amyotrophic lateral sclerosis (ALS) is difficult due to lack of definitive biomarkers. Our aim was to identify characteristic serum protein patterns that could provide candidate biomarkers for ALS. We divided mutant superoxide dismutase-1 (SOD1)H46R rats into three groups based on disease progression: pre-symptom (90 days), onset, and end-stage. After separation of serum proteins using two-dimensional electrophoresis, we selected clear protein spots and identified two candidate proteins—inter-alpha-trypsin inhibitor heavy chain H4 (ITIH4) and glutathione peroxidase 3 (Gpx3). The 120 kDa ITIH4 increased at the onset of the disease and the 85 kDa ITIH4, a cleaved form, at the end-stage in the sera of the SOD1H46R rats. Expression of the 85 kDa ITIH4 was substantial in ALS compared with controls or patients with muscular dystrophy, Alzheimer diseases, or Parkinson diseases. The Gpx3 protein levels in the sera of SOD1H46R rats were upregulated pre-symptom and gradually decreased as the disease progressed. The Gpx3 protein levels were lower in the sera of the patients with ALS than in other diseases. These results indicate that ITIH4 and Gpx3 are potential biomarkers for ALS.  相似文献   
37.
Purpose The aim of this study was to evaluate the enhancement behavior of pancreatic ductal carcinoma by contrast-enhanced sonography with agent detection imaging (ADI), and to clarify the origin of microbubble signals by comparisons with histological findings of resected specimens. Methods The subjects were 21 patients with resectable pancreatic carcinoma. The final histological diagnosis was tubular adenocarcinoma in 20 cases, and anaplastic carcinoma in one case. Ultrasound examinations were performed using an Acuson Sequoia 512 series system, and the contrast agent (Levovist) was injected intravenously in doses of 7 ml (300 mg/ml). The ADI signals (in the tumor) were recorded continuously for 30 s after an injection of Levovist (vascular image) and then obtained intermittently (30 s time-intervals) until the signal had diminished in pancreatic tissue (perfusion image). Results Contrast enhancement of the tumor was observed in 71.4% of subjects on the vascular image and 76.3% of subjects on the perfusion image. Enhancement patterns on the vascular image were classified into three types: VI-1 (linear enhancement), VI-2 (spotty enhancement), and VI-3 (no enhancement). VI-1, VI-2, and VI-3 were seen in 9 (42.8%), 6 (28.6%), and 6 (28.6%) of the 21 cases, respectively. Enhancement patterns on the perfusion image were classified into four types: PI-1 (diffuse uneven enhancement), PI-2 (spotty enhancement), PI-3 (peripheral enhancement), and PI-4 (negative enhancement). The incidence of PI-1, PI-2, PI-3, and PI-4 was 4.8%, 42.9%, 28.6%, and 23.8%, respectively. With respect to resectable cases, these enhancement patterns were compared with histological findings, i.e., the distribution of blood vessels in the tumor, remaining pancreatic tissues in the tumor, differentiation of types of adenocarcinoma, volume of stroma, and invasion types of carcinoma. The enhanced patterns consequently corresponded to either the distribution of the blood vessels or the remaining pancreatic tissues in the tumor. Conclusion This study indicated that pancreatic ductal carcinoma is frequently enhanced by microbubbles, and the signals seem to originate from fine blood vessels and the remaining pancreatic tissues in the tumor.  相似文献   
38.
BACKGROUND: Early initiation of bystander cardiopulmonary resuscitation (CPR) improves the chances of successful resuscitation and survival. The importance of bystander CPR is attracting more interest, and there has been an increase in attendance at CPR training courses in Japan. However, there have been few reports regarding Japanese attitudes toward the performance of bystander CPR. The present study was performed to identify current Japanese attitudes toward bystander CPR compared to our previous study performed in 1998. METHODS AND RESULTS: Between February and March 2006, participants were asked about their willingness to perform CPR in five varying scenarios, i.e., performing CPR on a stranger, a trauma patient, a child, an elderly person, and a relative, and CPR techniques consisting of chest compression plus mouth-to-mouth ventilation (CC plus MMV) versus chest compression only (CC only). A total of 4223 individuals (male 50%) completed the questionnaire, including high school students, teachers, emergency medical technicians (EMTs), medical nurses, and medical students. About 70% of the subjects had experienced CPR training more than once. Only 10-30% of high school students, teachers, and health care providers reported willingness to perform CC plus MMV, especially on a stranger or trauma victim. In contrast, 70-100% of these subjects reported willingness to perform CC only, which was the same as in our previous study. The reasons for the unwillingness among laypeople to perform CC plus MMV were inadequate knowledge and/or doubt regarding whether they could perform the techniques effectively, while health care providers reported a fear contracting of a disease. CONCLUSIONS: Most laypeople and health care providers are unlikely to perform CC plus MMV, especially on a stranger or trauma victim, but are more likely to perform CC only, as also found in our previous study in 1998. These findings suggest that MMV training should be de-emphasised and the awareness of CC alone should be emphasised because, for whatever reason, people do not want to perform MMV.  相似文献   
39.
Differences in effectiveness between haloperidol injection and oral atypical antipsychotics in the acute-phase treatment of schizophrenia are not well examined. We retrospectively investigated whether these treatment options affected the length of mechanical restraint. We used the Japanese Diagnosis Procedure Combination Database to identify schizophrenia patients who were involuntarily hospitalized and receiving mechanical restraint between July and December, 2006–2009. Data included patient demographics, use of antipsychotics, and number of days on which patients underwent mechanical restraint. Propensity score matching was performed to compare the number of days of mechanical restraint between the haloperidol injection group and the oral atypical antipsychotics group. We used survival analysis to examine whether the initial difference in treatment affected the number of days of mechanical restraint. Cox regression was performed to compare the concurrent effects of various factors. Among 1731 eligible patients, 574 were treated with haloperidol injections and 420 with atypical antipsychotics. Matching produced 274 patients in each group. Cox regression analysis showed that the initial therapeutic agents did not significantly affect the number of days of mechanical restraint. The results indicate that atypical antipsychotics were as effective as haloperidol injections in the acute-phase treatment of schizophrenia.  相似文献   
40.
BackgroundImmune checkpoint inhibitors (ICIs) are increasingly being used for the treatment of upper gastrointestinal cancers [esophageal cancer and gastric cancer (GC)]. They cause imbalances in immunological tolerance, resulting in immune-related adverse events (irAEs). Although irAEs have been reported to be associated with the efficacy of ICIs in some cancers, the relationship between irAEs and prognosis of upper gastrointestinal cancers remains unknown. This study aimed to investigate the prognostic impact of irAEs in patients with advanced or recurrent upper gastrointestinal cancer treated with nivolumab.MethodsWe retrospectively divided the patients (n=96) who received nivolumab into two groups: the irAEs group (n=41) and non-irAEs group (n=55), according to the Common Terminology Criteria for Adverse Events ver. 5.0.ResultsirAEs were significantly associated with good performance status and high serum albumin levels (all P<0.05). The irAEs group had a significantly longer overall survival (OS) than the non-irAEs group [log-rank P=0.003; univariate hazard ratio (HR) =0.36, 95% confidence interval (CI) =0.21–0.65, P<0.01; multivariate HR =0.47, 95% CI =0.26–0.88, P=0.018]. Importantly, in both esophageal cancer and GC, the irAEs group experienced favorable clinical outcomes compared with the non-irAEs group. In the multivariate analysis, male sex (P<0.01), presence of irAEs (P=0.018), and good pretreatment performance status (P<0.01) were independent prognostic factors.ConclusionsAmong patients with upper gastrointestinal cancer treated with nivolumab, the prognosis of patients who developed irAEs was better than that of patients who did not develop irAEs. Long-term continuation of nivolumab by early detection of irAEs and an appropriate response to irAEs are important.  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