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   4704篇
  免费   179篇
  国内免费   38篇
耳鼻咽喉   130篇
儿科学   216篇
妇产科学   128篇
基础医学   321篇
口腔科学   181篇
临床医学   356篇
内科学   1121篇
皮肤病学   80篇
神经病学   345篇
特种医学   206篇
外科学   1037篇
综合类   95篇
一般理论   1篇
预防医学   216篇
眼科学   102篇
药学   171篇
中国医学   13篇
肿瘤学   202篇
  2023年   44篇
  2022年   63篇
  2021年   131篇
  2020年   71篇
  2019年   104篇
  2018年   132篇
  2017年   78篇
  2016年   145篇
  2015年   139篇
  2014年   168篇
  2013年   263篇
  2012年   350篇
  2011年   341篇
  2010年   183篇
  2009年   162篇
  2008年   340篇
  2007年   365篇
  2006年   379篇
  2005年   340篇
  2004年   306篇
  2003年   231篇
  2002年   196篇
  2001年   25篇
  2000年   30篇
  1999年   26篇
  1998年   7篇
  1997年   8篇
  1996年   11篇
  1992年   19篇
  1991年   7篇
  1990年   15篇
  1989年   9篇
  1988年   17篇
  1987年   13篇
  1986年   17篇
  1985年   27篇
  1984年   13篇
  1983年   9篇
  1982年   9篇
  1981年   6篇
  1980年   6篇
  1979年   16篇
  1978年   12篇
  1977年   6篇
  1976年   5篇
  1974年   8篇
  1972年   9篇
  1970年   7篇
  1969年   9篇
  1968年   6篇
排序方式: 共有4921条查询结果,搜索用时 0 毫秒
41.
Methods:Data on 11 robot-assisted laparoscopic partial nephrectomies performed by using our technique from February 2015 through June 2015 were retrospectively analyzed. The robotic platform used was DaVinci Xi (Intuitive Surgical, Inc., Sunnyvale, California, USA) with a 3-arm setup. The AirSeal system (SurgiQuest, Milford, Connecticut, USA) was used as a port allowing simultaneous introduction of 2 instruments for the bedside surgeon, obviating the need for an additional (fourth) robotic arm. A long suction-and-irrigation device and atraumatic grasping forceps were used. Both instruments were introduced through the trocar of the AirSeal system, making simultaneous introduction and use possible. We preferred the long suction-and-irrigation device, because it minimizes collision of the instruments.Results:Mean age and BMI of the patients were 55 ±14.6 y and 29.18 ± 6.85, respectively. Seven tumors were on the right side and 4 were on the left. The mean size of the tumors was 32.45 mm (± 11.31). Surgical time was 132.2 minutes (±37.17), with an estimated blood loss and ischemia time of 103.63 mL (±65.92) and 16.72 minutes (±9.52), respectively. One patient had postoperative bleeding that was resolved without transfusion. The median hospitalization period was 3.9 d (±0.53). Loss of intra-abdominal pressure was not observed, and pressure was stable at 10 mm Hg.Conclusion:The AirSeal System and its valveless trocar eliminated the need for an additional port placement in our series. The technique is feasible, safe, and reproducible; therefore, it may be implemented in selected cases of robot-assisted partial nephrectomies.  相似文献   
42.
43.
44.
Classical cadherin cell-cell adhesion proteins play key morphogenetic roles during development and are essential for maintaining tissue integrity in multicellular organisms. Classical cadherins bind in two distinct conformations, X-dimer and strand-swap dimer; during cellular rearrangements, these adhesive states are exposed to mechanical stress. However, the molecular mechanisms by which cadherins resist tensile force and the pathway by which they convert between different conformations are unclear. Here, we use single molecule force measurements with an atomic force microscope (AFM) to show that E-cadherin, a prototypical classical cadherin, forms three types of adhesive bonds: catch bonds, which become longer lived in the presence of tensile force; slip bonds, which become shorter lived when pulled; and ideal bonds that are insensitive to mechanical stress. We show that X-dimers form catch bonds, whereas strand-swap dimers form slip bonds. Our data suggests that ideal bonds are formed as X-dimers convert to strand-swap binding. Catch, slip, and ideal bonds allow cadherins to withstand tensile force and tune the mechanical properties of adhesive junctions.  相似文献   
45.
46.
47.
48.
OBJECTIVES: The aim of this study was to investigate the various features of infectious disease (ID) consultations and the usage of antibiotics in a Turkish university hospital. METHODS: A total of 395 consultation requests were recorded during a three-year period. RESULTS: The departments most frequently requesting the consultation services of the ID department were Orthopedics (29.6%), Neurology (18.5%), Cardiology (11.8%) and Internal Medicine (10.4%). The main reasons were for diagnosis of unexplained fever (42.3%) and for antibiotic modification according to culture results (18%). Diagnoses made by the ID consultant were pneumonia (16.7%), urinary tract infections (9.3%), bone and joint prosthesis infections (9.1%) and in 15.7% of the investigated patients, no infectious focus was determined. It was recognized that the use of antibiotics had already been initiated in the great majority of patients (67.1%) before the consultation request. While the current therapy was changed in 57.4% of these patients, antibiotics were not necessary for 9.8%. CONCLUSIONS: Since the most common diagnoses were respiratory and urinary tract or bone and joint prosthesis infections, the ID specialists should have detailed knowledge of these problems. Usage of antibiotics without ID consultation was prevalent, therefore a continuous educational program is a necessity for healthcare workers in the hospital.  相似文献   
49.
It is known that cold exposure is accompanied by coronary artery vasoconstriction and ischemia in patients with coronary artery disease (CAD). The aim of the present study was to evaluate the response of left ventricular (LV) diastolic and systolic functions, estimated by means of Doppler echocardiography, to cold pressor test (CPT) in patients with CAD. Twenty-five male patients (mean age 50.8 +/- 8.1 years) with documented CAD underwent CPT with Doppler echocardiographic assessment of LV diastolic and systolic functions. According to the development of ischemic response to CPT, all patients were divided into 2 groups: group 1, 10 patients with ischemia and group 2, 15 patients without ischemia during CPT. Cold exposure caused significant increase in blood pressure with no changes in heart rate in all CAD patients. Patients with signs of ischemia during cold exposure had lower transmitral flow velocity during early filling (p < 0.001), prolonged isovolumic relaxation time (p < 0.04), shortened deceleration time of early transmitral flow velocity (p < 0.001), and higher values of Doppler-derived index of myocardial performance (p < 0.0001) than those without ischemic response to CPT. Cold exposure in CAD patients through stimulating of vasoconstriction and ischemia was associated with derangements in LV myocardial performance, manifested by delayed relaxation, impaired stiffness, and reduced contractility.  相似文献   
50.
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