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   909篇
  免费   73篇
  国内免费   6篇
耳鼻咽喉   1篇
儿科学   9篇
妇产科学   61篇
基础医学   148篇
口腔科学   22篇
临床医学   106篇
内科学   108篇
皮肤病学   8篇
神经病学   71篇
特种医学   248篇
外科学   52篇
综合类   3篇
一般理论   1篇
预防医学   59篇
眼科学   4篇
药学   41篇
肿瘤学   46篇
  2021年   5篇
  2020年   4篇
  2019年   12篇
  2018年   10篇
  2017年   4篇
  2015年   12篇
  2014年   15篇
  2013年   14篇
  2012年   21篇
  2011年   26篇
  2010年   13篇
  2009年   17篇
  2008年   27篇
  2007年   34篇
  2006年   37篇
  2005年   34篇
  2004年   42篇
  2003年   34篇
  2002年   31篇
  2001年   30篇
  2000年   34篇
  1999年   23篇
  1998年   27篇
  1997年   25篇
  1996年   18篇
  1995年   16篇
  1994年   25篇
  1993年   20篇
  1992年   11篇
  1991年   7篇
  1990年   19篇
  1989年   33篇
  1988年   33篇
  1987年   36篇
  1986年   22篇
  1985年   23篇
  1984年   34篇
  1983年   18篇
  1982年   22篇
  1981年   20篇
  1980年   20篇
  1979年   4篇
  1978年   19篇
  1977年   12篇
  1976年   8篇
  1975年   4篇
  1974年   4篇
  1972年   4篇
  1920年   3篇
  1913年   3篇
排序方式: 共有988条查询结果,搜索用时 15 毫秒
91.
Percutaneous nephrostolithotomy, which can require a double puncture, is presently the method of choice in our institution for the removal of renal stones. Patients that underwent this procedure were evaluated to identify the possible reasons for the double puncture. Of 200 patients evaluated, 14 needed a second tract. The three variables that determined whether a second puncture was needed, in order of importance, were number and size of the stones, with second tracts needed in patients with multiple stones and staghorn calculi; anatomical variations of the renal collecting system itself, with bifid systems the most significant anatomic variation; and the dexterity of the radiologist in performing the puncture and the ability of the urologist to extract the stone. Second tracts were needed more frequently in patients who presented with stones in both the lower and middle poles of the collecting systems.  相似文献   
92.
Experience with the Amplatz retrievable vena caval filter. Work in progress   总被引:1,自引:0,他引:1  
The Amplatz retrievable vena caval filter was designed in an attempt to decrease complications associated with the placement of Mobin-Uddin or Kimray-Greenfield filters. The design allows percutaneous retrieval, thus expanding application of the filter to situations requiring temporary prophylaxis against pulmonary embolism. Filters have been placed in 16 patients, nine (56%) for prophylactic purposes. All filters were easily inserted percutaneously. Complications occurred in three patients; these included complete thrombosis of the inferior vena cava below the filter, misplacement of one filter into the pericaval retroperitoneal tissue, and development of thrombus cranial to the filter. With the current introduction system, the possibility of filter misplacement has been essentially eliminated. No patient experienced symptoms suggestive of pulmonary embolism after filter insertion. One filter retrieval has been performed, with no complications.  相似文献   
93.
94.
Dr. Crum's six lines of attack are: bettered scientific methods in infant and pre-school care; extension of school hygiene, medical inspection and physical training, more intensive health education of the people and the extension of industrial sanitation and industrial hygiene.  相似文献   
95.
The role of perfusion pressure and flow during cardiopulmonary bypass with moderate hypothermia and hemodilution in the development of new postoperative renal or clinically apparent cerebral dysfunction was examined in 504 adults. Cardiopulmonary bypass flow was targeted at greater than 40 mL.kg-1.min-1 and pressure at greater than 50 mm Hg. Flows and pressures less than target occurred in 21.6% and 97.1% of patients, respectively. Fifteen patients (3.0%) suffered new renal and 13 (2.6%) new central nervous system dysfunction. Low pressure or flow during cardiopulmonary bypass, expressed in absolute values or in intensity-duration units, were not predictors of either adverse outcome. Multivariate analysis identified use of postoperative intraaortic balloon counterpulsation (p less than 10(-6], excessive blood loss in the ICU (p less than 10(-4], need for vasopressors before cardiopulmonary bypass (p less than 10(-4], postoperative myocardial infarction (p less than 10(-3], emergency reoperation (p less than 0.002), excessive postoperative transfusion (p less than 0.02), and chronic renal disease (p less than 0.03) as independent predictors of postoperative renal dysfunction. Independent predictors of postoperative central nervous system dysfunction were cardiopulmonary resuscitation in the intensive care unit (p less than 10(-6], intracardiac thrombus or valve calcification (p less than 0.02), and chronic renal disease (p less than 0.03). Age greater than 65 years (40.7% of patients) did not predict either outcome. We conclude that failure of the native circulation during periods other than cardiopulmonary bypass rather than the flows and pressures considered here is the major cause of renal and clinically apparent central nervous system dysfunction after cardiac operations.  相似文献   
96.
97.
BACKGROUND: Mucinous differentiation of the endometrium can occur in a spectrum of changes ranging from benign (metaplasia) to malignant (adenocarcinomas with mucinous differentiation). Mucinous proliferations with simple architecture are generally considered benign; however, more complex growth patterns have an uncertain biologic behavior, particularly when these changes are focal and/or are encountered in biopsy or curettage material. The disparity between the degree of cytologic atypia and the neoplastic potential makes their interpretation difficult in routine practice. We categorized and prospectively studied a series of these lesions based upon their degree of architectural complexity and correlated them with follow-up curettings and hysterectomies over a period of three years. METHODS: Mucinous proliferations of the endometrium were subdivided into three categories (A, B, or C) based upon increasing degrees of architectural complexity. Type A were mucin-containing epithelial cells, present singly or in small tufts, within architecturally benign glands or involving the endometrial surface. Type B proliferations were more complex, consisting of mucin-containing epithelial cells forming small pseudoglands with rigid, punched out spaces and no supporting stroma Conspicuous cytologic atypia or architectural features such as a filiform growth pattern characterized type C alterations. One hundred two curettings and 36 hysterectomies from 52 patients were reviewed. RESULTS: Patient's ages ranged from 39 to 71 years (median, 55 yr); 41 patients (80%) were over age 50. Twenty patients (40%) were receiving hormone replacement therapy. Nineteen type A, 17 type B, and 16 type C mucinous endometrial proliferations were analyzed. Excluding those cases in which a conventional coexisting precancerous lesion was also present in the initial endometrial sample, the percentages of endometrial carcinoma following a curettage diagnosis of types A to C, respectively, were 0, 64.7%, and 100%. Carcinomas following type B alterations were all well-differentiated and all were confined to the endometrium or inner third of the myometrium. CONCLUSION: Mucinous endometrial proliferations comprise a spectrum subdivisable into biologically meaningful subsets. A high percentage of type B alterations were found to have endometrial adenocarcinoma on follow-up; however, all were well-differentiated and showed either no or minimal invasion. This finding suggests that the absence of cytologic atypia in complex mucinous lesions identifies subsets of lesions at low concurrent risk for deeply invasive cancer. The presentation of type B lesions as predominantly microglandular surface lesions without co-existing atypical hyperplasias suggests that a subset of well-differentiated adenocarcinomas arise via neoplastic alterations in surface epithelium.  相似文献   
98.
99.
100.
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