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   2110篇
  免费   120篇
  国内免费   75篇
耳鼻咽喉   2篇
儿科学   176篇
妇产科学   38篇
基础医学   234篇
口腔科学   58篇
临床医学   276篇
内科学   516篇
皮肤病学   76篇
神经病学   72篇
特种医学   396篇
外科学   99篇
综合类   44篇
预防医学   100篇
眼科学   19篇
药学   87篇
  2篇
肿瘤学   110篇
  2023年   6篇
  2022年   7篇
  2021年   14篇
  2020年   14篇
  2019年   19篇
  2018年   37篇
  2017年   23篇
  2016年   23篇
  2015年   43篇
  2014年   50篇
  2013年   66篇
  2012年   45篇
  2011年   44篇
  2010年   94篇
  2009年   86篇
  2008年   54篇
  2007年   91篇
  2006年   57篇
  2005年   60篇
  2004年   27篇
  2003年   21篇
  2002年   29篇
  2001年   40篇
  2000年   29篇
  1999年   33篇
  1998年   131篇
  1997年   155篇
  1996年   131篇
  1995年   108篇
  1994年   114篇
  1993年   98篇
  1992年   31篇
  1991年   41篇
  1990年   39篇
  1989年   56篇
  1988年   48篇
  1987年   42篇
  1986年   49篇
  1985年   45篇
  1984年   27篇
  1983年   16篇
  1982年   24篇
  1981年   31篇
  1980年   27篇
  1979年   6篇
  1978年   8篇
  1977年   18篇
  1976年   27篇
  1975年   14篇
  1973年   2篇
排序方式: 共有2305条查询结果,搜索用时 0 毫秒
991.
To date, at least four genes involved in DNA mismatch repair, hMSH2, hMLH1, hPMS1 and hPMS2, have been demonstrated to be altered in the germline of patients with hereditary nonpolyposis colorectal cancer (HNPCC). Additionally, defective mismatch repair is thought to account for the observation of microsatellite instability (MIN) in tumors from these patients. The genetic defect responsible for the MIN+ phenotype in sporadic colorectal cancer, however, has yet to be clearly delineated. In order to better understand the role of somatic and germline alterations within hMSH2 and hMLH1 in the process of colorectal tumorigenesis, we examined the entire coding regions of both of these genes in seven patients with MIN+ sporadic colorectal cancer, 19 patients with familial colorectal cancer, and 20 patients meeting the strict Amsterdam criteria for HNPCC. Thirteen germline, two somatic, and four neutral alterations were identified. The two somatic mutations occurred in patients having familial cancer, while the germline mutations were distributed among one sporadic (14%), three familial (16%), and nine HNPCC (45%) cases. All patients with identified mutations in the mismatch repair genes, whose tumors were available for analysis, demonstrated MIN. On the other hand, we could not identify mutations in the subset of clinically defined HNPCC patients with MIN negative tumors nor in the majority (6/7) of MIN+ sporadic tumors.   相似文献   
992.
0 引言 慢性鼻炎是一种常见的多发病.中医认为,人体卫气不固之时感受外邪而发病.由于四时气候变化不同及人体差异,而有夹寒、夹热、夹暑、夹湿之别,以风寒、风热为多见.肺合皮毛,开窍于鼻,病邪侵袭致使卫气闭郁,肺气不宜,而恶寒发热,鼻塞、流涕.如急性期不及时治疗、鼻塞加重,鼻分泌物增多.西医可诊断为,单纯性鼻炎,肥厚性鼻炎,慢性鼻窦炎等.目前,对慢性鼻炎治疗效果不佳.我科采用贴耳针治疗本病,取得了较满意效果.1 对象和方法1.1 对象 1992~1998我科收治慢性鼻炎患者35例.均作者简介:孙 静…  相似文献   
993.
994.
Summary Under static loading during weight-lifting, the lumbosacral spine essentially exhibits horizontalisation of the base of the sacrum (superior plateau of S1). We have attempted to elicit the mechanism of this horizontalisation by means of radiographs. These do not demonstrate any movements of the sacroiliac joints or plasticity of the hip bones. However, a symmetrical rotation of the hip joints conditions a retroversion of the pelvic girdle which explains the horizontalisation of the upper sacral plateau. This fixation of the block of the pelvic girdle is under muscular control, so that this mechanism can be improved by appropriate training.
Mécanismes d'orientation du socle pelvi-fémoral au cours de la mise en charge statique du rachis lombaire chez l'haltérophile
Resumé Sous charge statique, chez l'haltérophile, le rachis lombosacré présente essentiellement une horizontalisation du plateau supérieur de S1. Par radiographies, nous avons tenté de déterminer le mécanisme de cette horizontalisation. Les mouvements au niveau de la sacro-iliaque et la plasticité des os coxaux ne peuvent pas être mis en évidence sur les radiographies. Par contre, une rotation symétrique des coxo-fémorales détermine une rétroversion de la ceinture pelvienne permettant d'expliquer l'horizontalisation du plateau sacré. Ce verrouillage du bloc de la ceinture pelvienne est sous la dépendance des muscles et en conséquence, ce mécanisme peut être amélioré par un entraînement approprié.
  相似文献   
995.
We report the characterization of a de novo unbalanced chromosome rearrangement by comparative genomic hybridization (CGH) in a 15-day-old child with hypotonia and dysmorphia. We describe the combined use of CGH and fluorescence in situ hybridization (FISH) to identify the origin of the additional chromosomal material on the short arm of chromosome 6. Investigation with FISH revealed that the excess material was not derived from chromosome 6. Identification of unknown unbalanced aberrations that could not be identified by traditional cytogenetics procedures is possible by CGH analysis. Visual analysis of digital images from CGH-metaphase spreads revealed a predominantly green signal on the telomeric region of chromosome 10p. After quantitative digital ratio imaging of 10 CGH-metaphase spreads, a region of gain was found in the chromosome band 10p14-pter. The CGH finding was confirmed by FISH analysis, using a whole chromosome 10 paint probe. These results show the usefulness of CGH for a rapid characterization of de novo unbalanced translocation, unidentifiable by karyotype alone.  相似文献   
996.
BACKGROUND. Although preeclampsia is an important and relatively common medical problem, its pathophysiology remains unresolved and the search for a biochemical marker that precedes the hemodynamic abnormalities of preeclampsia continues. We designed a study to investigate the hemodynamic changes that characterize preeclampsia and to evaluate the metabolism of platelet intracellular calcium as a possible predictor of the development of preeclampsia. METHODS. Hemodynamic measurements and spectrofluorometric determinations of the levels of intracellular calcium in platelets in the basal state and after stimulation with an agonist were performed in 48 nulliparous black women during each trimester of pregnancy. The data on the 14 women (29 percent) in whom preeclampsia developed were then compared with the data on the other 34, who served as normotensive controls. RESULTS. There was no significant difference between the two groups in the basal levels of intracellular calcium at any time. In contrast, the levels measured after arginine vasopressin was administered during the first trimester indicated an exaggerated response in the group with preeclampsia as compared with the control group (1494 +/- 388 [+/- SEM] percent vs. 545 +/- 55 percent of base line; P less than 0.0002), which was sustained through the second and third trimesters. All but three of the women with preeclampsia had responses higher than the highest response among the controls. Platelet intracellular calcium responses to arginine vasopressin during the first trimester were a sensitive predictor of the subsequent development of preeclampsia (P less than 0.00009). Although vascular resistance was similar in the two groups during the first trimester, it subsequently decreased in the control group (P less than 0.02) but not in the group with preeclampsia. CONCLUSIONS. Our findings indicate that preeclampsia is characterized by the absence of the normal pregnancy-related decrease in vascular resistance, which is preceded in most instances by an exaggerated response of platelet intracellular calcium to arginine vasopressin early in pregnancy. We therefore propose that an increase in the sensitivity of platelet calcium to arginine vasopressin can be used as an early predictor of subsequent preeclampsia.  相似文献   
997.
In 20 patients with congenital and acquired lymphedema in either upper or lower extremities and in four patients without extremity edema, human serum albumin labeled with technetium-99m was injected intradermally into a digital web space of the hand or foot. With a digital gamma camera that permitted a "sweep" of the torso, serial extremity and whole-body lymphagioscintigraphy (LAS) of the peripheral lymphatic system was performed. In 11 patients with acquired lymphedema, a well-defined obstructive pattern was seen, characterized by discrete peripheral lymphatic trunks, delayed or absent depiction of regional nodes, and delayed but extensive soft-tissue tracer extravasation. Five of nine patients with congenital lymphedema showed hypoplasia characterized by poorly defined lymphatic trunks, delayed depiction of regional nodes, and early and extensive extravasation of tracer. The other four patients showed aplasia, with absence of trunks, no depiction of nodes, and little or no tracer extravasation. LAS is technically simple to perform and requires no special training. Radiation exposure is minuscule, and the procedure is safe and without apparent side effects. For these reasons, whole-body LAS should be the preferred method for the initial assessment of congenital or acquired lymphedema.  相似文献   
998.
999.
Background:This article presents the design of PROFILe, a study investigating which (bio)medical and non-(bio)medical patient characteristics should guide more tailored chronic care. Based on this insight, the project aims to develop and validate ‘patient profiles’ that can be used in practice to determine optimal treatment strategies for subgroups of chronically ill with similar healthcare needs and preferences.Methods/Design:PROFILe is a practice-based research comprising four phases. The project focuses on patients with type 2 diabetes. During the first study phase, patient profiles are drafted based on a systematic literature research, latent class growth modeling, and expert collaboration. In phase 2, the profiles are validated from a clinical, patient-related and statistical perspective. Phase 3 involves a discrete choice experiment to gain insight into the patient preferences that exist per profile. In phase 4, the results from all analyses are integrated and recommendations formulated on which patient characteristics should guide tailored chronic care.Discussion:PROFILe is an innovative study which uses a uniquely holistic approach to assess the healthcare needs and preferences of chronically ill. The patient profiles resulting from this project must be tested in practice to investigate the effects of tailored management on patient experience, population health and costs.  相似文献   
1000.
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