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   97474篇
  免费   9475篇
  国内免费   209篇
耳鼻咽喉   1382篇
儿科学   2796篇
妇产科学   2000篇
基础医学   13677篇
口腔科学   2418篇
临床医学   11640篇
内科学   18069篇
皮肤病学   1477篇
神经病学   7884篇
特种医学   3367篇
外国民族医学   10篇
外科学   13647篇
综合类   1973篇
一般理论   83篇
预防医学   10604篇
眼科学   2349篇
药学   7769篇
  1篇
中国医学   115篇
肿瘤学   5897篇
  2021年   1301篇
  2020年   829篇
  2019年   1305篇
  2018年   1603篇
  2017年   1163篇
  2016年   1291篇
  2015年   1485篇
  2014年   2017篇
  2013年   3217篇
  2012年   4272篇
  2011年   4625篇
  2010年   2454篇
  2009年   2367篇
  2008年   4085篇
  2007年   4506篇
  2006年   4408篇
  2005年   4437篇
  2004年   4271篇
  2003年   3962篇
  2002年   3901篇
  2001年   2841篇
  2000年   2910篇
  1999年   2663篇
  1998年   1284篇
  1997年   1071篇
  1996年   1031篇
  1995年   959篇
  1994年   943篇
  1993年   881篇
  1992年   2178篇
  1991年   2107篇
  1990年   1986篇
  1989年   1947篇
  1988年   1861篇
  1987年   1851篇
  1986年   1762篇
  1985年   1770篇
  1984年   1550篇
  1983年   1397篇
  1982年   1047篇
  1981年   926篇
  1980年   795篇
  1979年   1299篇
  1978年   982篇
  1977年   899篇
  1976年   848篇
  1975年   831篇
  1974年   952篇
  1973年   841篇
  1972年   797篇
排序方式: 共有10000条查询结果,搜索用时 93 毫秒
51.
A major problem in tracheal transplantation is the restoration of an adequate vascular supply to the transplanted trachea. In 12 piglets, a segment (6 rings) of thoracic trachea was removed and the excised segment was then sutured back in place. In 9 animals (group A), a vascularized omental flap was wrapped around the autotransplanted trachea. In the other 3 pigs (group B), the omentum was not used. Eight of 9 group A pigs were killed, 1 or 2 months later, having had no signs of airway obstruction; the 9th pig was killed after 14 days because of airway obstruction. The 3 pigs in group B were killed after 11 to 13 days because of progressive respiratory obstruction. In the 8 asymptomatic pigs in group A, the omental flap was viable and tracheal growth was normal with no differences in diameter between normal and autotransplanted trachea. Histologically intact cartilage was lined with respiratory epithelium. In the one group A pig who was killed early, the omental flap was necrotic. In this pig and in the 3 group B animals, extensive tracheal necrosis and nonviable cartilage were observed. These findings indicate that in the pig, a 6-ring segment of trachea can be transplanted with vascularization provided by an omental flap.  相似文献   
52.
Rats, initiated to self-administer 10% (v/v) ethanol in an operant situation using the sucrose-fading procedure, received bilateral n. accumbens microinjections of d-amphetamine prior to operant sessions. Doses of 4 micrograms, 10 micrograms and 20 micrograms/brain were administered and some animals also received a 4 microgram/brain dose of LY171555. Three different effects were observed: increased, decreased and no change in total session responding. There was no clear relation between injection area in the n. accumbens and type of effect observed. For either an increase or decrease in total session responding, momentary response rates were decreased. Both d-amphetamine and LY171555 produced similar results. The data support the hypothesis that dopamine in the n. accumbens is involved with ethanol reinforced operant responding but in a complex manner.  相似文献   
53.
Complete Freund's adjuvant (CFA) administered before sensitization dampened the normal and cyclophosphamide-enhanced response of high and moderate IgE responder phenotype mice (CAF1 and C57B1/6J, respectively). CFA-induced suppression of IgE biosynthesis was effective in reducing anaphylactic histamine release from approximately 2,900 ng histamine per milliliter to background levels (less than 100 ng/ml). CFA-induced ascites fluid was able to reduce the cyclophosphamide-enhanced IgE response of low-responder phenotype SJL mice from 1:320 to less than 1:5 as determined by passive cutaneous anaphylaxis. Muramyl dipeptide, a mycobacterial cell wall component capable of eliciting effects similar to those seen with CFA, was shown to induce suppression of IgE production if incorporated in incomplete Freund's adjuvant. Muramyl dipeptide administered in saline was ineffective, while incomplete Freund's adjuvant alone had some immunoregulatory properties. Ongoing IgE responses were less susceptible to regulation. CFA administered to sensitized C57B1/6J mice was ineffective in inducing IgE suppression when animals were challenged with antigen.  相似文献   
54.
Horner's syndrome or oculosympathetic paralysis is not an uncommon finding in patients with head and neck neoplasms. While in most cases the syndrome is easily established at the bedside, it can be confirmed and topographically defined as a central, preganglionic, or postganglionic lesion through sequential pharmacologic testing. The importance of such localization lies in differentiating neoplasia vs. a benign condition as the cause of the syndrome. Such variants as congenital Horner's, an alternating Horner's, and a pseudo-Horner's syndrome are discussed in regard to their differential features.  相似文献   
55.
56.
The Scottish Heart Health Study is a study of lifestyle and coronary heart disease risk factors in 10,359 men and women aged 40-59 years, in 22 districts of Scotland. The study was conducted during 1984-86, when Scotland had the highest national coronary heart disease mortality reported by the World Health Organisation. A self-completed questionnaire, complemented by a 40 minute visit to a survey clinic, staffed by nurses, enabled the classical major risk factors and some more newly described ones to be measured. The study emphasised quality control and representativeness, and incorporated a World Health Organisation protocol for measurement of key items to allow comparisons in place and time, and therefore also to provide a definitive baseline against which interventions can be assessed. This paper describes the overall findings. Current cigarette smokers constitute 39% of men and 38% of women, higher levels than those reported in England but lower than previous Scottish reports. Mean blood pressure levels were 134/84 mmHg for men and 131/81 mmHg in women, lower than in British studies of the 1960s and 1970s. Mean body mass index levels, 26.1 Kg/m2 in men and 25.7 Kg/m2 in women, were not high by international standards. However, mean serum cholesterol levels were 6.4 mmol/l in men and 6.6 mmol/l in women--as high as those in previous British studies and high by international standards. Levels of high density lipoprotein cholesterol, non-fasting triglycerides and fibrinogen are also reported. Physical activity both at work and in leisure time was low.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
57.
Sex and racial predilection, social history, and histology were analyzed in a biopsy-proven adenocarcinoma of the lower esophagus/esophagogastric junction collected over a 5-year period in two teaching institutions with different patient populations. Adenocarcinoma occurred in 11% of patients with biopsy-proven esophageal cancer. The disease occurred only in males at one center, and in a 7:1 ratio of males to females at the other center. Clear racial predilection was seen, since 12 of 13 patients with adenocarcinoma of the esophagus were white, whereas less than 20% of patients with squamous carcinoma of the esophagus were white. The finding of Barrett's epithelium in eight of the 13 cases strongly supports the theory that in white males, Barrett's epithelium is a precursor lesion of adenocarcinoma of the esophagus/esophagogastric junction.  相似文献   
58.
59.
Long-term dialysis patients frequently develop acquired renal cystic disease (ARCD). The discovery of ARCD and renal cell carcinoma in one of our hemodialysis patients led us to review the literature. ARCD has been described mainly in the maintenance hemodialysis (MH) population. Therefore, we investigated 20 peritoneal dialysis (PD) patients for ARCD using ultrasonography. Seven patients (35%) had detectable cysts and two patients (10%) had multiple bilateral cysts. One patient had a large asymptomatic complex cyst that proved to be an adenocarcinoma. Our study suggests that ARCD is relatively common in the PD population, and we speculate that it may be related more to length of time in end-stage renal disease (ESRD) than to the mode of dialysis. The potential for malignant change appears to justify a routine screening examination with ultrasonography and/or computerized tomography (CT) to detect this recently described and probably underrecognized entity.  相似文献   
60.
The anti-granulocyte activity of serum from patients with B-cell chronic lymphocytic leukaemia (CLL) and other lymphoproliferative disorders was investigated. Granulocyte-binding IgG was measured in 34 patients with CLL, 13 patients with hairy cell leukaemia, one patient with prolymphocytic leukaemia, two patients with Sézary cell leukaemia, and seven patients with chronic T-cell lymphocytosis who had a predominance of circulating large granular lymphocytes. Anti-granulocyte activity was absent in CLL and its variants, but present in the majority of granulocytopenic patients with chronic T-cell lymphocytosis. In one of these patients, granulocytopenia was associated with complement-activating IgG granulocyte antibody. Thus, antibody-mediated granulocyte injury appears to be an unusual occurrence in chronic lymphocytic leukaemia, but is a frequent complication of chronic T-cell lymphocytosis.  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