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   4274篇
  免费   297篇
  国内免费   21篇
耳鼻咽喉   27篇
儿科学   173篇
妇产科学   94篇
基础医学   640篇
口腔科学   83篇
临床医学   440篇
内科学   952篇
皮肤病学   85篇
神经病学   352篇
特种医学   189篇
外科学   424篇
综合类   137篇
一般理论   3篇
预防医学   319篇
眼科学   55篇
药学   279篇
中国医学   8篇
肿瘤学   332篇
  2023年   40篇
  2022年   61篇
  2021年   154篇
  2020年   82篇
  2019年   104篇
  2018年   100篇
  2017年   72篇
  2016年   113篇
  2015年   117篇
  2014年   131篇
  2013年   190篇
  2012年   259篇
  2011年   265篇
  2010年   163篇
  2009年   129篇
  2008年   228篇
  2007年   236篇
  2006年   232篇
  2005年   211篇
  2004年   187篇
  2003年   167篇
  2002年   172篇
  2001年   82篇
  2000年   63篇
  1999年   74篇
  1998年   75篇
  1997年   54篇
  1996年   45篇
  1995年   32篇
  1994年   55篇
  1993年   18篇
  1992年   45篇
  1991年   35篇
  1990年   42篇
  1989年   40篇
  1988年   50篇
  1987年   36篇
  1986年   39篇
  1985年   33篇
  1984年   31篇
  1983年   29篇
  1982年   21篇
  1981年   18篇
  1980年   16篇
  1979年   21篇
  1978年   16篇
  1977年   15篇
  1976年   14篇
  1972年   12篇
  1966年   10篇
排序方式: 共有4592条查询结果,搜索用时 15 毫秒
941.
In order to evaluate the effects of pentoxifylline on sperm motility and longevity, a controlled in-vitro study was conducted on normozoospermic donor semen samples using the Cellsoft automated system for sperm motility analysis. After incubation and selection, pentoxifylline was found to improve the recovery of spermatozoa and to increase their velocity. In the subgroup of progressively motile spermatozoa, curvilinear velocity was also enhanced. It is concluded that pentoxifylline has an effect on the vigour, but not on the pattern, of sperm motion. Pentoxifylline did not improve the motility characteristics of senescent spermatozoa in normozoospermic sperm samples. Sperm survival, as shown by supra-vital staining, and motility longevity both decreased with time after pentoxifylline treatment.  相似文献   
942.
943.
Retrospective study of 121 cases of adnexal masses which were managed laparoscopically was carried out. The aim of study was to evaluate the safety and effectiveness of laparoscopic management of adnexal masses. In 120 cases, procedure was completed safely with minimum morbidity. In one case laparotomy had to be done to complete the procedure. In 76 cases cystectomy was done, 26 required salpingo-oophorectomy and 19 required only salpingectomy. Histologic evaluation revealed 30 functional cysts, 36 endometriotic cysts, 11 dermoids, 9 serous cystadenomas, 3 mucinous cystadenomas, 11 parovarian cysts, 19 cases of hydrosalpinx and 2 cases of tuberculosis.Key Words: Adnexal mass, Laparoscopy, Ovarian cyst  相似文献   
944.
945.

Background

To evaluate the usefulness and limitations of graded compression ultrasonography in the diagnosis of clinically equivocal cases of suspected acute appendicitis at the setting of mid zonal military hospital of India.

Methods

A prospective study, graded compression ultrasonography with self localization was carried out with 3.5 MHz convex, 5 MHz convex and 7.5 MHz linear transducers (Wipro GE) in 69 clinically equivocal suspected cases of acute appendicitis. With maximal compression the anteroposterior diameter of appendix was measured from outer to outer wall. The main criterion for diagnosing appendicitis was demonstration of a non compressible appendix with anteroposterior dimension of 7mm or more.

Result

Sonologically 36 (52%) cases were diagnosed as appendicitis. Anteroposterior outer diameter of inflamed appendices ranged from 7mm to 21mm (mean 10.5mm). 30 (83%) of 36 patients could accurately self localize the point of maximum tenderness. There were 01 false positive and 04 false negative cases. Sensitivity and specificity were 89.7% and 96.6% respectively. Positive and negative predictive values were 97.2% and 87.8% respectively. Alternative diagnoses were offered in 33 (47.8%) cases. Amongst these 33 cases, 14(42.4%) had abdominal pain of unknown origin. Gynaecologic, urologic and gastrointestinal aetiologies were established in 10(30.3%), 07(21.2%) and 02(6%) cases respectively.

Conclusion

Graded compression ultrasonography superadded with self localization is an accurate means of diagnosing/excluding appendicitis in clinically equivocal cases of acute appendicitis and it is of great value in establishing alternative diagnoses.Key Words: Ultrasonography, Acute appendicitis  相似文献   
946.
ABSTRACT

Objective: The aim of this study was to gain knowledge about how the integration of personal and professional experiences affects therapeutic work. Method: Therapists (N?=?14) who had been recommended by their leaders at their individual workplaces were interviewed twice with semi-structured qualitative interviews, which were then subjected to thematic and Interpretative Phenomenological Analysis. Results: All the therapists in the sample described their personal qualities as an experienced tension between their personal strengths and vulnerabilities in the therapeutic setting. This tension came to expression through four subordinate themes: (a) The tension between perceiving oneself as a helper while dealing with one’s own needs for attention and care; (b) The tension between the ability for embodied listening to the patient while tuning into oneself; (c) The tension between staying present while handling aggression and rejection from clients; and (d) The tension in striving for a constructive balance between closeness and distance. Conclusion: The results point to ways in which the personal selves of the therapists may affect their professional role performance. Drawing upon previous research and literature on the topic, the paper discusses how therapists’ personal qualities are experienced as affecting their work and suggests several implications for psychotherapy training and practice.  相似文献   
947.

Objective

Kurtosis beamforming is a useful technique for analysing magnetoencephalograpy (MEG) data containing epileptic spikes. However, the implementation varies and few studies measure concordance with subsequently resected areas. We evaluated kurtosis beamforming as a means of localizing spikes in drug-resistant epilepsy patients.

Methods

We retrospectively applied kurtosis beamforming to MEG recordings of 22 epilepsy patients that had previously been analysed using equivalent current dipole (ECD) fitting. Virtual electrodes were placed in the kurtosis volumetric peaks and visually inspected to select a candidate source. The candidate sources were compared to the ECD localizations and resection areas.

Results

The kurtosis beamformer produced interpretable localizations in 18/22 patients, of which the candidate source coincided with the resection lobe in 9/13 seizure-free patients and in 3/5 patients with persistent seizures. The sublobar accuracy of the kurtosis beamformer with respect to the resection zone was higher than ECD (56% and 50%, respectively), however, ECD resulted in a higher lobar accuracy (75%, 67%).

Conclusions

Kurtosis beamforming may provide additional value when spikes are not clearly discernible on the sensors and support ECD localizations when dipoles are scattered.

Significance

Kurtosis beamforming should be integrated with existing clinical protocols to assist in localizing the epileptogenic zone.  相似文献   
948.
949.
Ida Perrotta 《Journal of anatomy》2020,237(6):1015-1025
Once regarded merely as a bland lipid storage disease consequence of aging, atherosclerosis is currently considered a slow and continuous inflammatory process (partially controllable by treatment) with complex etiology involving a multitude of genetic and environmental risk factors which ultimately result in the formation of the plaque. The vascular endothelium, a monolayer of endothelial cells (ECs), is an important regulatory "organ" critical for cardiovascular homeostasis in health which also contributes significantly to the pathomechanisms of several disease states, including atherosclerosis. Over the years, there has been evidence highlighting the central role of endoplasmic reticulum (ER) in the maintenance of endothelial function and perturbations in ER biology have been proposed to adversely affect a diverse range of endothelial functions. Of particular interest is the evidence that under certain pathophysiological circumstances, abnormal ER ultrastructure correlates with altered ER function and signaling and can contribute to cell injury and apoptosis. Therefore, the ultrastructural traits of ER membranes can have important implications not only for their functional bearings but also for the etiology and pathophysiology of diverse human disorders. With regard to atherosclerosis, the focus of ER research has been centered on the molecular signals originated from the ER to manage conditions of stress, leaving the fine structure of this organelle an almost unexplored (but promising) area of studies. There is, also, increasing evidence that mitochondrial dysfunction plays a critical role in promoting cell apoptosis, inflammation, and oxidative stress, thereby contributing to atheroma growth. It is within this context that the present study has been undertaken to investigate the microscopic architecture of ECs in human atherosclerosis and to determine whether the potential structural abnormalities of ER and mitochondria may play a central pathogenic role in atherogenesis or may merely reflect the condition of a tissue whose integrity has already been disturbed or destroyed. For this purpose, transmission electron microscopy (TEM) remains a powerful technique that can not only provide information about the ultrastructural state of cell organelles but also allow the correlation between different subcellular alterations indicative of a certain pathophysiological condition and cellular response. The present study expands the spectrum of ultrastructural defects known to exist in human atherosclerosis and suggests that ER alterations may be of great importance in the pathogenesis of the disease. The architectural changes of ER may be considered early pathological events that precede any overt histologic abnormalities in the vascular endothelium and its subcellular organelles, primarily the mitochondrial pool.  相似文献   
950.
Abstract

Introduction

The Danish National Patient Registry (DNPR) has been the source of several epidemiological studies of inflammatory bowel disease (IBD). However, the validation dates back to 1996 and lacks outpatient records and disease classification. The aim of this study was to update the validation and assess the validity and reliability of using the registry in disease classification.  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