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   3166013篇
  免费   244814篇
  国内免费   6901篇
耳鼻咽喉   46179篇
儿科学   99103篇
妇产科学   84646篇
基础医学   445337篇
口腔科学   90740篇
临床医学   287960篇
内科学   611284篇
皮肤病学   66670篇
神经病学   258167篇
特种医学   126196篇
外国民族医学   1088篇
外科学   478582篇
综合类   75847篇
现状与发展   9篇
一般理论   1206篇
预防医学   246435篇
眼科学   74927篇
药学   242197篇
  31篇
中国医学   7958篇
肿瘤学   173166篇
  2018年   33504篇
  2017年   25942篇
  2016年   28679篇
  2015年   32791篇
  2014年   46404篇
  2013年   69095篇
  2012年   93775篇
  2011年   98783篇
  2010年   58536篇
  2009年   55490篇
  2008年   92315篇
  2007年   98414篇
  2006年   99527篇
  2005年   96122篇
  2004年   92477篇
  2003年   89170篇
  2002年   87436篇
  2001年   150109篇
  2000年   155208篇
  1999年   130976篇
  1998年   36833篇
  1997年   33154篇
  1996年   32899篇
  1995年   31519篇
  1994年   29458篇
  1993年   27471篇
  1992年   104284篇
  1991年   100533篇
  1990年   97389篇
  1989年   94056篇
  1988年   87015篇
  1987年   85328篇
  1986年   80922篇
  1985年   77054篇
  1984年   57656篇
  1983年   49003篇
  1982年   29069篇
  1981年   25694篇
  1979年   53680篇
  1978年   37262篇
  1977年   32014篇
  1976年   29394篇
  1975年   31657篇
  1974年   38540篇
  1973年   36654篇
  1972年   34504篇
  1971年   32060篇
  1970年   30096篇
  1969年   28233篇
  1968年   25545篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
981.
Abstract: Background: Few studies have examined in depth the labor progression of multiparas to determine if there is any additional impact of being parous beyond the first birth. The objective of this study was to determine the effect of parity on labor progression in contemporary obstetric practice. Methods: Our sample consisted of all low‐risk women who delivered a term, live‐born infant from January 2002 to March 2004 at a single institution in Delaware, United States (n = 5,589). The median duration of labor by each centimeter of cervical dilation was computed for parity = 0 (n = 2,645); parity = 1 (n = 1,839); parity = 2 (n = 750); and parity = 3 + (n = 355). Results: Multiparas had a significantly faster labor progression from 4 to 10 cm (293, 300, and 313 min, respectively, for parity = 1, parity = 2, and parity = 3 +), compared with nulliparas (383 min for parity = 0), as well as a shorter second stage of labor. However, no significant differences were found in duration of the active phase or the second stage of labor among multiparas. Conclusions: Additional childbearing appears to have no effect of on the progression of labor among multiparous subgroups. The difference in duration of the active phase between nulliparas and multiparas is substantially smaller in a contemporary population. (BIRTH 33:1 March 2006)  相似文献   
982.
Mandibular prognathism (MP) or skeletal Class III malocclusion with a prognathic mandible is one of the most severe maxillofacial deformities. Facial growth modification can be an effective method of resolving skeletal Class III jaw discrepancies in growing children with dentofacial orthopedic appliances including the chincup, face mask, maxillary protraction combined with chincup traction and the Fr?nkel functional regulator III appliance. Orthognathic surgery in conjunction with orthodontic treatment is required for the correction of adult MP. The two most commonly applied surgical procedures to correct MP are sagittal split ramus osteotomy (SSRO) and intraoral vertical ramus osteotomy. Both procedures are suitable for patients in whom a desirable occlusal relationship can be obtained with a setback of the mandible, and each has its own advantages and disadvantages. In bilateral SSRO, the intentional ostectomy of the posterior part of the distal segment can offer long-term positioned stability. This may be attributable to reduction of tension in the pterygomasseteric sling that applies force in the posterior mandible. While various environmental factors have been found to contribute to the development of MP, heredity plays a substantial role. The relative contributions of genetic and environmental components in the etiology of MP are unclear. The recent identification of the genetic susceptibilities to MP constitutes the first step toward understanding the molecular pathogenesis of MP. Further studies in molecular biology are needed to identify the gene-environment interactions associated with the phenotypic diversity of MP and the heterogenic developmental mechanisms thought to be responsible for them.  相似文献   
983.
OBJECTIVES: Pseudotumour cerebri has been previously recognized as a neurological side effect of combined oral contraceptives but has not been diagnosed with a delay of 3 years after initiation of combined oral contraceptives. CASE REPORT: A 19-year-old obese woman developed visual impairment and headache, 4 months after starting combined oral contraceptives. Three years later symptoms deteriorated and she presented with prominent tendon-jerks and congested optical-discs. Normal CSF drained with high pressure from the spinal tap. Pseudotumour cerebri was diagnosed. Headache and visual impairment resolved within 3 weeks after discontinuation of combined oral contraceptives. CONCLUSIONS: Combined oral contraceptives-induced pseudotumour cerebri may remain undetected for years. Young, obese women with visual impairment and headache under combined oral contraceptives should undergo immediate neurological and ophthalmological investigation.  相似文献   
984.
In order to assess the state and pathology of the woman's pelvis minor, a number of methods are commonly used among practitioners, encompassing clinical exploration, radiology, MRN, urodynamics, endoscopy and echography.

Echography has been poorly used in clinical pelvic exploration and its reliability is actually a matter of controversy 1. However, echographic surveys can provide us with valuable gynecological data on the state and pathologies of the soft pelvis, within the genital regions or even going beyond them, i.e. the rectal channel, bladder, urethra, anus, vascular plexuses, and all of their supporting tissues.

At our research unit, we have been employing Transvaginal Ultrasound echography (TVU) for a long time in conjunction with other pelvis-focused methods in order to study different kinds of pelvic alterations. TVU has proven to be friendly to use, fast, harmless and inexpensive, allowing serial explorations and producing high-quality dynamic images (loop-cinema, video-tape). Furthermore, this method is fairly aseptic in that the occurrence of faeces in the rectal ampolla is not a nuisance but a bonus in tracking the contours of the rectum walls and other topographical features which would be otherwise difficult to survey.

A complete pelvic floor TVU may add no longer than 5-8 minutes to a routine gynecological examination, can be implemented by the general gynecologist and generates data that can be further studied by the appropriate specialist for a more insightful evaluation 2.  相似文献   
985.
The goal of this retrospective study concerning primary carcinoma of the vagina (PCV) was to analyze clinical and histopathologic prognostic factors in one of the largest known material, which comprised 314 patients. PCV is a rare disease, and the majority of published studies are based on small materials; therefore, the established knowledge concerning prognostic factors is insufficient. Routine treatment is based on irradiation with risk for undertreatment or overtreatment, which leads to unnecessary complications in the absence of prognostic factors. The overall 5-year disease-specific survival rate in this study was 45% and in stage I 75%. In the univariate statistical analysis, several factors correlated significantly with disease-specific survival. However, in the multivariate analysis, there were only three factors that independently could predict poor survival-high age at diagnosis, large tumors (> or =4 cm), and advanced stage. Common background factors with no prognostic significance were prior hysterectomy, other gynecological malignancies, and pelvic irradiation. In conclusion, this study has elucidated three strong prognostic factors that might be considered in the choice of therapy and also for modification of the FIGO guidelines. Increased knowledge concerning complementary biologic markers to discriminate between low- and high malignant tumors is however of great importance.  相似文献   
986.
987.
988.
989.
990.
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