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   2948篇
  免费   178篇
  国内免费   8篇
耳鼻咽喉   63篇
儿科学   196篇
妇产科学   43篇
基础医学   308篇
口腔科学   138篇
临床医学   199篇
内科学   581篇
皮肤病学   70篇
神经病学   233篇
特种医学   138篇
外科学   453篇
综合类   80篇
预防医学   115篇
眼科学   104篇
药学   198篇
中国医学   15篇
肿瘤学   200篇
  2023年   21篇
  2022年   64篇
  2021年   145篇
  2020年   70篇
  2019年   96篇
  2018年   107篇
  2017年   81篇
  2016年   100篇
  2015年   83篇
  2014年   149篇
  2013年   159篇
  2012年   242篇
  2011年   202篇
  2010年   131篇
  2009年   77篇
  2008年   123篇
  2007年   153篇
  2006年   154篇
  2005年   126篇
  2004年   107篇
  2003年   70篇
  2002年   63篇
  2001年   46篇
  2000年   61篇
  1999年   53篇
  1998年   32篇
  1997年   25篇
  1996年   19篇
  1995年   11篇
  1994年   8篇
  1992年   22篇
  1991年   22篇
  1990年   29篇
  1989年   18篇
  1988年   17篇
  1987年   23篇
  1986年   21篇
  1985年   16篇
  1984年   18篇
  1983年   12篇
  1982年   8篇
  1978年   11篇
  1977年   10篇
  1976年   9篇
  1975年   16篇
  1974年   11篇
  1973年   9篇
  1972年   10篇
  1971年   11篇
  1970年   8篇
排序方式: 共有3134条查询结果,搜索用时 15 毫秒
11.
Intestinalized epithelium in traditional long-segment Barrett's esophagus (BE) shows increased proliferative activity, which is postulated to be an early step in the metaplasia-dysplasia-carcinoma sequence. The aim of this study was to evaluate the proliferative activity of intestinalized epithelium of the distal esophagus and gastroesophageal junction (IMEGEJ). Tissue sections from 78 consecutive patients (20 with IMEGEJ, 58 without IMEGEJ) who had elective upper gastrointestinal endoscopy over a 6-month period were immunohistochemically stained with MIB-1, the Ki-67 proliferation-antigen-associated marker, for evaluation of the crypt MIB-1 proliferation index (PI), size of the proliferative zone (PZ), and the presence of surface epithelial staining. Data from the IMEGEJ and non-IMEGEJ groups, and from 15 age-matched patients with traditional long-segment BE (>3.0 cm), were compared statistically. IMEGEJ patients showed a statistically significant increase in the mean crypt PI compared with non-IMEGEJ controls (21.9+/-19.5 v 14.3+/-9.3; P=.01). In addition, IMEGEJ cases showed an increase in the mean crypt PZ (52.3+/-16.4 v 45.2+/-17.2; P=.05), and a trend toward an increase in the percentage of cases with MIB-1-positive surface epithelial cells (50% v 33%, P=.18). Patients with IMEGEJ did not differ from patients without IMEGEJ with respect to any other clinical or histological feature, including signs or symptoms of gastroesophageal reflux disease and presence or absence of esophagitis or carditis. The MIB-1 results of the patients with long-segment BE (MIB-1 PI = 22.6+/-20.5, MIB-1 PZ = 51.8+/-19.6, proportion of cases with MIB-1-positive surface cells = 66%) were similar to those with IMEGEJ. Intestinalized epithelium in the distal esophagus or gastroesophageal junction shows increased proliferative activity in comparison with patients without intestinalized epithelium. This finding supports an increased risk of carcinogenesis in patients with IMEGEJ.  相似文献   
12.
Summary Lectin-histochemical studies were performed on paraffin-embedded brain tissue sections to identify the specific sugar residues of undegraded stored substances in the cytoplasm of globoid cells from patients with globoid cell leukodystrophy. We studied brain tissues from six human patients with galactosylceramide lipidosis (i. e., Krabbe's disease) and compared them to brain tissues from animals with a similar enzyme deficiency including seven Twitcher mice, three dogs and two cats. The globoid cells in all 18 cases studied stained with succinylated-wheat germ agglutinin (S-WGA), but did not stain withDilichos biflorus agglutinin, soybean agglutinin orUlex europaeus agglutinin-I.Bandeirea simplicifolia agglutinin-I stained the globoid cells in Twitcher mice, dogs and cats but not those in humans.Concanavalia ensiformis agglutinin, wheat germ agglutinin andRicinus communis agglutinin-I all stained each of the globoid cells in the mouse, dog and cat tissues, but only in some of the human cases. Peanut agglutinin, however, variably stained globoid cells in the mouse and dog cases but not at all in the human and cat cases. These results demonstrate a common terminal carbohydrate residueN-acetyl glucosamine, which binds S-WGA in the undergraded material stored within the globoid cells in galactoceramide lipidosis. These cells also contained various other stored molecules with sugar residues whose nature is determined by species or individually.Supported by grants NS21765 and HD05515 from the National Institutes of Health  相似文献   
13.
14.
Most metatarsal neck fractures can be successfully treated non-operatively in a cast boot. Displaced metatarsal neck fractures tend to be less stable and have a propensity for the distal fragment to angulate, secondary to the strong flexor tendons, which often forces the distal fracture fragment in a plantar direction and leads to relative metatarsal shortening. Most literature is focussed on antegrade fixation of metatarsal neck fractures using pre-bent K wires or thin elastic nails. Apart from the technical challenges, this technique is limited when bones are osteoporotic as the pre-bent distal end of the K-wire may penetrate the plantar cortex of the proximal metatarsal and prevent the wire from entering the medullary canal of the metatarsal and advancing to the fracture site. Furthermore, when the medullary canal is narrow especially in Asian patients, it may be difficult to pass a bent K-wire through the isthmus of the metatarsal shaft. We describe an innovative technique of closed transverse wiring of the metatarsal head necks that has a distinct advantage in Asian population with osteoporotic bones. With percutaneous manipulation using digital pressure, closed reduction of fracture fragments of the most displaced fracture is done under fluoroscopic guidance to achieve a satisfactory alignment followed by closed transverse wiring of the metatarsal heads. With this procedure, adjacent fractures remain stable within an acceptable range because of intermetatarsal ligaments connected to the adjacent intact head. Our technique has a relatively short operating time and allows for early motion of the metatarso-phalangeal joint. This is especially useful for those with osteoporosis, narrow canal, soft tissue compromise, intra-operative failure of ante-grade pinning and in scenarios of limited surgical equipment/expertise.  相似文献   
15.
62% of India's population is comprised of mothers and children, for whom many health agencies provide maternal and child (MCH), and family planning (FP) services. 249 adult members from three villages of Primary Health Center, Telegaon, in Wardha district, were interviewed to assess the awareness and use of these services. Each village had government and private health agencies providing MCH and FP services. Adequate knowledge of MCH and FP services, however, is one of the prerequisites for using services; 85-89.5% knew of promotive services. The awareness of nutritional programs, school health services, and health education, however, were lower in the range 7.9-36.3%. Similar findings have been reported in previous studies. The knowledge of MCH services was significantly different between educated and uneducated respondents. As for service use, antenatal care service and immunization coverages were 80-86% and 56.96%, respectively. Earlier studies found coverages of only 9.6-50% for antenatal care services and 45-69% for immunizations. FP practice was high in all three villages due to the priority given to those services by the government. This study demonstrates the ability of education facilities and services availability to increase the knowledge and practice of MCH and FP services in the interest of realizing targets established by the World Health Organization by the year 2000.  相似文献   
16.
17.
The main objectives of this study were to reassess complications associated with transrectal ultrasound-guided biopsies (TRUSBx) of the peripheral zone (PZ) and to compare morbidity of exclusive PZ biopsy to morbidity associated with two additional transition zone (TZ) biopsies. We distributed a self-administered questionnaire assessing TRUSBx complications to 883 consecutive patients who underwent two systematic TZ TRUSBx in addition to systematic sextant PZ TRUSBx, and to 383 consecutive patients who underwent exclusive PZ TRUSBx. Of 316 (35.8%) patients subjects to TZ and PZ TRUSBx, 71% experienced hematuria, 63% hematospermia, 39% rectal bleeding, and 2.2% temperature elevation greater than 38°C. Of 137 (35.8%) patients who exclusively underwent PZ TRUSBx, 57%, 62%, 36%, and 1.4% reported these complications, respectively. Symptom duration and severity were similar in both groups. Although we report a substantially higher incidence of biopsy complications than previously published, these complications are self limited and require no intervention. Furthermore there appears to be no significant difference between complication rates associated with exclusive PZ biopsy compared with those associated with two additional biopsies of the TZ.  相似文献   
18.
We report the case of a myodil cyst causing a thoracic radiculopathy in a patient who had undergone a myelogram 30 years previously. Although myodil is no longer used, sequelae can continue to be seen for many years.  相似文献   
19.
We previously reported that diethylstilbestrol (DES) or estradiol valerate (EV) exposure at a dose of 0.10-0.12 mg/kg, or higher, per day, on alternate days, from postnatal days 2-12, resulted in abnormal penis development and infertility (H. O. Goyal et al., 2005, J. Androl. 26, 32-43). The objective of this study was to identify a critical developmental period(s) during which EV exposure results in the observed penile abnormalities. Male pups received EV at a dose of 0.10-0.12 mg/kg on postnatal day(s) 1, 1-3, 4-6, 1-6, 7-12, 13-18, 19-24, or 25-30. Fertility was tested at 102-115 days of age and tissues were examined at 117-137 days. Both penile morphology and fertility were unaltered in rats treated with EV after 12 days of age. Conversely, except in rats treated on postnatal day 1 only, none of the males treated prior to 12 days of age sired pups, and all had abnormal penises, including varying degrees of abnormal accumulation of fat cells and loss of cavernous spaces and smooth muscle cells in the corpora cavernosa penis, which were maximal in the 1-6-day group. Also, the preputial sheath was partially released or its release was delayed, and the weight of the bulbospongiosus muscle was significantly reduced. Plasma testosterone (T) in the 1-6- and 4-6-day groups and intratesticular T in the 4-6-day group were significantly lower. The testosterone surge, characteristic of controls in the first week of life, was suppressed in the 1-3-day group. Estrogen receptor alpha mRNA expression was enhanced in the body of the penis in the 1-3-day group, but not in the 13-18-day group. Hence, EV exposure prior to 12 days of age (as short as 1-3 days postnatal), but not after 12 days of age, results in long-term abnormal penile morphology, characterized by abnormal accumulation of fat cells in the corpora cavernosa penis and, consequently, loss of fertility.  相似文献   
20.
Neurilemmoma of the cervical sympathetic chain is a rare nerve tumour. Less than 40 confirmed cases have been reported in the literature.1 2 Sometimes they can he mistaken as carotid body tumour but usual presentation of these lesions is an asymptomatic neck mass. Because of the rarity of the tumour we report another case of neurilemmoma arising from cervical sympathetic chain in a 19 years old male.  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