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   2920088篇
  免费   213884篇
  国内免费   4880篇
耳鼻咽喉   41040篇
儿科学   94344篇
妇产科学   80265篇
基础医学   427263篇
口腔科学   80656篇
临床医学   261455篇
内科学   566521篇
皮肤病学   63939篇
神经病学   231455篇
特种医学   110876篇
外国民族医学   803篇
外科学   443881篇
综合类   61738篇
现状与发展   12篇
一般理论   1058篇
预防医学   226340篇
眼科学   68383篇
药学   216284篇
  11篇
中国医学   5746篇
肿瘤学   156782篇
  2019年   23290篇
  2018年   32244篇
  2017年   24509篇
  2016年   27248篇
  2015年   30738篇
  2014年   43571篇
  2013年   65796篇
  2012年   90173篇
  2011年   96003篇
  2010年   57294篇
  2009年   54182篇
  2008年   90584篇
  2007年   96352篇
  2006年   97479篇
  2005年   94645篇
  2004年   90543篇
  2003年   87346篇
  2002年   85076篇
  2001年   131707篇
  2000年   135175篇
  1999年   114133篇
  1998年   33119篇
  1997年   29348篇
  1996年   29532篇
  1995年   27740篇
  1994年   25689篇
  1993年   24270篇
  1992年   88868篇
  1991年   86261篇
  1990年   84495篇
  1989年   81362篇
  1988年   75012篇
  1987年   73758篇
  1986年   69438篇
  1985年   66511篇
  1984年   49694篇
  1983年   42389篇
  1982年   25342篇
  1979年   45899篇
  1978年   32702篇
  1977年   27276篇
  1976年   26026篇
  1975年   28153篇
  1974年   33920篇
  1973年   32402篇
  1972年   30383篇
  1971年   28592篇
  1970年   26658篇
  1969年   25259篇
  1968年   23451篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
The purpose of this study was to compare prognostic models evaluating the probability of an ovarian cancer occurrence based on a number of clinical and ultrasonographic data in women with adnexal masses. A total of 686 women with adnexal masses underwent the examinations between 1994 and 2002. The recorded parameters included: age, menopausal status, body mass index, the grayscale and Doppler ultrasonographic examination, and selected markers concentration levels. In order to find the best combination of features, which significantly influences the probability of malignancy, stepwise logistic regression analysis, as well as artificial neural network, was used. The diagnostic efficiency of received models was estimated and compared using receiver-operating characteristics (ROC) curve. The results indicate that 431 and 255 patients had a benign and malignant ovarian tumor, respectively. Application of stepwise logistic regression analysis revealed statistically significant importance of eight features. The sensitivity and specificity for the received model were 65.71% and 77.59%, respectively. Three-layer perceptron network shows 13 features as significant predictors of malignancy. The network gave a sensitivity of 85.7% and specificity of 93.1%. Comparison of area under ROC curve for received models was 0.9679 vs 0.9716. Prognostic values of the analyzed neural model are not optimal but seem to surpass logistic regression model in terms of the predictive possibilities.  相似文献   
992.
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   
993.
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   
994.
995.
A 41-year-old Chinese lady had a Gr?fenberg ring in utero for 15 years. During that period of time, she had one normal vaginal delivery a year after insertion, followed by an ectopic pregnancy 12 years later. We discuss the possible mechanism of action of the Gr?fenberg ring and sequelae of its prolonged presence in the uterus.  相似文献   
996.
Pathophysiology of SPINK mutations in pancreatic development and disease.   总被引:1,自引:0,他引:1  
The endogenous pancreatic trypsin inhibitor, SPINK, is believed to limit enzyme activity in the pancreas and reduce the risk of pancreatitis. Recently, mutations in the SPINK1 gene have been associated with development of both acute and chronic pancreatitis. In most patients with SPINK1 mutations, the genetic variants do not cause the disease independently, but may act in concert with other genetic or environmental factors. Recent studies, using mice in which the trypsin inhibitor gene has been deleted or overexpressed, provide novel insights into the role of SPINK in pancreatic development and pancreatitis.  相似文献   
997.
998.
999.
1000.
In this study, we examine the prevalence of finding isolated tumor cells (ITCs) in negative lymph nodes of endometrial cancer patients using immunohistochemistry. Seventy-six endometrial cancer patients with lymph nodes histologically negative for metastatic disease were examined. Nodal tissue sections were stained with anticytokeratin antibodies AE-1 and CAM 5.2. Nodes with single or groups of cells (two to four cells) < or =0.2 mm and showing cytokeratin reactivity were positive for ITCs. Findings were compared to features of the primary tumor and patient outcome. ITCs were present in 31 of 1712 lymph nodes. Fifteen (19.7%) patients had ITC-positive nodes. ITCs involved only pelvic nodes in nine cases, only para-aortic nodes in five cases, and pelvic and para-aortic in one case. Tumor in adnexa was the only pathologic feature associated with nodal ITCs (P= 0.0485). All 15 patients with nodal ITCs were alive at follow-up. One (6.7%) patient suffered recurrent disease but was alive at last encounter. Disease recurred in 5 (8.8%) of 57 patients without nodal ITCs. Two are alive without disease, two alive with disease, and one died from her cancer. In summary, a significant proportion of endometrial cancer patients have ITCs detected by immunohistochemistry in histologically negative regional lymph nodes.  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